Cardiac Cardiac DysrythmiasDysrythmias

Definition of TermsDefinition of Terms

Ablation – purpose destruction Ablation – purpose destruction of heart muscle cells, usually in of heart muscle cells, usually in an attempt to control a an attempt to control a dysrhythmia.dysrhythmia.

Antiarrhythmic – a medication Antiarrhythmic – a medication that suppresses or prevents a that suppresses or prevents a dysrhythmia.dysrhythmia.

Conductivity – ability of the cardiac Conductivity – ability of the cardiac muscle to transmit electrical muscle to transmit electrical impulses.impulses.

Defibrillation – electrical current Defibrillation – electrical current administered to stop a dysrhythmia.administered to stop a dysrhythmia.

Depolarization – process by which Depolarization – process by which cardiac muscle cells change from a cardiac muscle cells change from a more negatively charged to a more more negatively charged to a more positively charged intracellular state. positively charged intracellular state.

Dysrhythmia (also referred to as Dysrhythmia (also referred to as arrhythmia) – disorder of the arrhythmia) – disorder of the formation or conduction (or both) formation or conduction (or both) of the electrical impulse within of the electrical impulse within the heart, altering the heart rate, the heart, altering the heart rate, heart rhythm, or both and heart rhythm, or both and potentially causing altered blood potentially causing altered blood flow. flow.

Implantable Cardioverter Implantable Cardioverter Defibrillator (ICD) – a device Defibrillator (ICD) – a device implanted into the chest to treat implanted into the chest to treat dysrhythmias.dysrhythmias.

Inhibited – in reference to Inhibited – in reference to pacemakers term used to pacemakers term used to describe the pacemaker with describe the pacemaker with holding an impulse (not firing).holding an impulse (not firing).

P wave – the part of an P wave – the part of an electrocardiogram (ECG) that electrocardiogram (ECG) that reflects conduction of an reflects conduction of an electrical impulse through the electrical impulse through the atrium; a trial depolarization.atrium; a trial depolarization.

Paroxysmal – a dysrhythmias Paroxysmal – a dysrhythmias that has a sudden onset and/or that has a sudden onset and/or termination and is usually of termination and is usually of short duration.short duration.

PR interval- the part of an ECG PR interval- the part of an ECG that reflects conduction of an that reflects conduction of an electrical impulse from the electrical impulse from the sinoatrial (SA) node through the sinoatrial (SA) node through the atrioventricular (AV) node.atrioventricular (AV) node.

Proarrthythmic – an agent that Proarrthythmic – an agent that causes or exacerbates a causes or exacerbates a dysrhythmia.dysrhythmia.

QRS complex – the of an ECG QRS complex – the of an ECG that reflects conduction of an that reflects conduction of an electrical impulse through the electrical impulse through the ventricles; ventricular ventricles; ventricular depolarization.depolarization.

QT interval – the part of an ECG QT interval – the part of an ECG that reflects the time from that reflects the time from ventricular depolarization to ventricular depolarization to repolarization.repolarization.

Repolarization – process by Repolarization – process by which cardiac muscle cells return which cardiac muscle cells return to a more negatively charged to a more negatively charged intracellular condition, their intracellular condition, their resting state.resting state.

Sinus rhythm – electrical activity Sinus rhythm – electrical activity of the heart initiated by the of the heart initiated by the sinoartrial (SA) node.sinoartrial (SA) node.

ST segment – The part of an ECG ST segment – The part of an ECG that reflects the end of that reflects the end of ventriocular depolarization (end ventriocular depolarization (end of the T wave).of the T wave).

Supraventricular tachycardia Supraventricular tachycardia (SUT) – a rhythm that originated (SUT) – a rhythm that originated in the conduction system above in the conduction system above the ventricles.the ventricles.

T wave – the part of an ECG that T wave – the part of an ECG that reflects repolarization of the reflects repolarization of the ventricles.ventricles.

Triggered – reference to Triggered – reference to pacemakers, term used to pacemakers, term used to described the release of an described the release of an impulse in response to some impulse in response to some stimulus.stimulus.

U wave – the part of an ECG that U wave – the part of an ECG that may reflect purkinje fiber may reflect purkinje fiber repolarization.repolarization.

Ventricular tachycardia (UT) – a Ventricular tachycardia (UT) – a rhythm that originated in the rhythm that originated in the ventricles.ventricles.

DysrhythmiasDysrhythmias

Disorders of the formation or Disorders of the formation or conduction or both of the conduction or both of the electrical impulse within the electrical impulse within the heart.heart.

Disorders can cause Disorders can cause disturbances of the heart rate, disturbances of the heart rate, the heart rhythm or both.the heart rhythm or both.

Dysrhythmias may initially be Dysrhythmias may initially be evidenced by the hemodynamic evidenced by the hemodynamic effect they cause (e.g. a change effect they cause (e.g. a change inconduction may change the inconduction may change the pumping action of the heart and pumping action of the heart and cause decreased blood pressure.cause decreased blood pressure.

Dysrhythmias are diagnosed by Dysrhythmias are diagnosed by analyzing the analyzing the electrocardiographic waveform.electrocardiographic waveform.

Types of DysrhythmiasTypes of Dysrhythmias

Dysrhythmias include sinus Dysrhythmias include sinus node, atrial, junctional, and node, atrial, junctional, and ventricular dysrhythmias and ventricular dysrhythmias and their various subcategories.their various subcategories.

Sinus Node Sinus Node DysrhythmiasDysrhythmias

Sinus Bradycardia – Sinus Sinus Bradycardia – Sinus bradycardia occurs when the bradycardia occurs when the sinus node creates an impulse at sinus node creates an impulse at a slower – than – normal rate.a slower – than – normal rate.

Cause:Cause: Lower metabolicneeds (sleep, Lower metabolicneeds (sleep,

athletic training, hypothermia, athletic training, hypothermia, hypothyroidism)hypothyroidism)

Vagal Stimulation (vomiting, Vagal Stimulation (vomiting, suctioning, severe pain, suctioning, severe pain, extreme emotions)extreme emotions)

Medications (calcium channel Medications (calcium channel blockers, amiodarone, beta-blockers, amiodarone, beta-blockersblockers

Incvenced intracvanial Incvenced intracvanial pressure,and myocardial pressure,and myocardial infarction (MI), especially of the infarction (MI), especially of the inferior wall.inferior wall.

Characteristicsof of Sinus Characteristicsof of Sinus bradycardiabradycardia

Ventricular & atrial rate : less Ventricular & atrial rate : less than 60 in the adultthan 60 in the adult

Ventricular & atrial rhythm : Ventricular & atrial rhythm : regularregular

QRS shape & duration: Usually QRS shape & duration: Usually normal, but may be regularly normal, but may be regularly abnormalabnormal

P: QRS ration: 1:1P: QRS ration: 1:1

Sinus Tachycardia – Sinus Sinus Tachycardia – Sinus tachycardia occurs when the tachycardia occurs when the sinus node creates an impulse at sinus node creates an impulse at a faster – than – normal rate.a faster – than – normal rate.

Cause:Cause: Acute blood loss, anemia, Acute blood loss, anemia,

shock, hyperrolemia, shock, hyperrolemia, hypovolemia congestive heart hypovolemia congestive heart failure, pain, hypermetabolic failure, pain, hypermetabolic states, fever, exercise,anxiety states, fever, exercise,anxiety or sympathomimetic or sympathomimetic medications medications

ECG criteria for sinus ECG criteria for sinus tachycardiatachycardia

Ventricular & atrial rate: greater Ventricular & atrial rate: greater then 100 in the adultthen 100 in the adult

Ventricular & atrial rhythm: regularVentricular & atrial rhythm: regular QRS shape & duration – usally QRS shape & duration – usally

normal, but may be regularly normal, but may be regularly abnormalabnormal

P wave: normal & consistent P wave: normal & consistent shape: always in front of the QRS, shape: always in front of the QRS, but may be buried in the preceding but may be buried in the preceding T waveT wave

PR interval – Consistent interval PR interval – Consistent interval between 0.12 & 0.20 secondsbetween 0.12 & 0.20 seconds

P: QRS ratio: 1:1P: QRS ratio: 1:1

Treatment for Sinus Treatment for Sinus tachycardiatachycardia

Calcium channel blockers & beta-Calcium channel blockers & beta-blockers used to reduce the blockers used to reduce the heart rate quicklyheart rate quickly

Sinus Arrhythmia – Sinus Sinus Arrhythmia – Sinus arrhythmia occurs when the arrhythmia occurs when the sinus node creates an impulse at sinus node creates an impulse at an irregular rhythm; the rate an irregular rhythm; the rate usually increase with inspiration usually increase with inspiration and decrease with expirationand decrease with expiration

Causes:Causes: Nonrespiratory causes include Nonrespiratory causes include

heart disease & valvular heart disease & valvular disease, but these are rarely disease, but these are rarely seenseen

ECG criteria for sinus ECG criteria for sinus arrhythmiaarrhythmia

Ventricular & atrial rate: 60 to Ventricular & atrial rate: 60 to 100 in the adult100 in the adult

Ventricular and atrial rhythm: Ventricular and atrial rhythm: irregularirregular

QRS shape & duration: usually QRS shape & duration: usually normal, but may be regularly normal, but may be regularly abnormalabnormal

P wave: normal & consistent P wave: normal & consistent shape: always in front of the QRSshape: always in front of the QRS

PR interval: consistent interval PR interval: consistent interval between 0.12 and 0.20 secondsbetween 0.12 and 0.20 seconds

P: QRS ratio: 1:1P: QRS ratio: 1:1

Atrial DysrhythmiasAtrial Dysrhythmias

Premature atrial complex – A Premature atrial complex – A premature atrial complex (PAC) premature atrial complex (PAC) is a single ECG complex that is a single ECG complex that occurs when an electrical occurs when an electrical impulse starts in the atrium impulse starts in the atrium before the next impulse of the before the next impulse of the sinus nodesinus node

Causes:Causes: Caffeine, alcohol, nicotine, Caffeine, alcohol, nicotine,

stretched atrial myocardium stretched atrial myocardium (as in hyperrolemia), anxiety, (as in hyperrolemia), anxiety, hypokalemia (low potassium hypokalemia (low potassium level), hepermetabolic states, level), hepermetabolic states, or atrial ischemia, injury or or atrial ischemia, injury or infarctioninfarction

Characteristics of PAC’sCharacteristics of PAC’s

Ventricular and atrial rate: Ventricular and atrial rate: depends on the underlying depends on the underlying rhythm (e.g. sinus tachycardia)rhythm (e.g. sinus tachycardia)

PR interval: The early P wave has PR interval: The early P wave has a shorter – than – normal PR a shorter – than – normal PR interval but still between 0.12 & interval but still between 0.12 & 0.20 seconds0.20 seconds

Ventricular and atrial rhythm: Ventricular and atrial rhythm: Irregular due to early P waves, Irregular due to early P waves, creating a PP invertal that is creating a PP invertal that is shorter than the others. This is shorter than the others. This is sometimesfollowed by a longer – sometimesfollowed by a longer – than – normal PP interval, but one than – normal PP interval, but one that is less than twice the normal that is less than twice the normal PP interval. This type of interval is PP interval. This type of interval is called a noncompesatory pause.called a noncompesatory pause.

QRS shape and duration: the QRS shape and duration: the QRS that follows the early P QRS that follows the early P wave is usually normal, but it wave is usually normal, but it may be adnormal (aberrantly may be adnormal (aberrantly conducted PAC). It may even be conducted PAC). It may even be absent (blocked PAC)absent (blocked PAC)

P wave: an early and different P P wave: an early and different P wave may be seen or may be wave may be seen or may be hidden in the T wave: other P hidden in the T wave: other P waves in the strip are consistent.waves in the strip are consistent.

P: QRS ratio: usually 1:1P: QRS ratio: usually 1:1 Atrial Flutter – atrial flutter occurs Atrial Flutter – atrial flutter occurs

in the atrium and creates in the atrium and creates impulses at an atrial rate between impulses at an atrial rate between 250 & 400 times per minute. 250 & 400 times per minute. Because the atrialrate is faster Because the atrialrate is faster than the AV node can conduct, not than the AV node can conduct, not all trial impulses are conducted all trial impulses are conducted into the ventricles, causing a into the ventricles, causing a therapatic block at the AV node.therapatic block at the AV node.

Causes:Causes: Similar to atrial fibrillationSimilar to atrial fibrillation

Characteristics of Atrial Characteristics of Atrial FluttersFlutters

Ventricular & Atrial rate: Atrial Ventricular & Atrial rate: Atrial rates ranges between 250 and rates ranges between 250 and 400: ventricular rate usually 400: ventricular rate usually ranges between 75 and 150ranges between 75 and 150

Ventricular and Atrial rhythm: Ventricular and Atrial rhythm: The atrial rhythm is irregular The atrial rhythm is irregular because of a change in the AV because of a change in the AV conductionconduction

QRS shape and duration: usually QRS shape and duration: usually normal, but may be abnomal or normal, but may be abnomal or may be absentmay be absent

P wave: Sawtoothed shape: P wave: Sawtoothed shape: These waves make it refered to These waves make it refered to as F wavesas F waves

PR interval: multiple F waves PR interval: multiple F waves may make it difficult to may make it difficult to determine the PR intervaldetermine the PR interval

P: QRS ratio: 2:1, 3:1,or 4:1P: QRS ratio: 2:1, 3:1,or 4:1

Sx/S:Sx/S:

Chest pain, shortness of breath, Chest pain, shortness of breath, & lowblood pressure& lowblood pressure

TreatmentTreatment

If patient is unstableIf patient is unstable

- electro cardioversion- electro cardioversion

If patient is stableIf patient is stable

- Diltiazem (Cardizem)- Diltiazem (Cardizem)

- Verapamil(Calan, Isoptin)- Verapamil(Calan, Isoptin)

- Beta-blockers or digitalis- Beta-blockers or digitalis

- Flecainide (Tambocor)- Flecainide (Tambocor)

- Ibutilide (Corvert)- Ibutilide (Corvert)

- Dofetilide (Tikosyn)- Dofetilide (Tikosyn)

- Quinidine - Quinidine (Cardioquin, (Cardioquin, Quinaglute)Quinaglute)

Atrial Fibrillation – Atrial Atrial Fibrillation – Atrial fibrillation causes a rapid, fibrillation causes a rapid, disorganized, & uncoordinates disorganized, & uncoordinates twitching of atrial musculature. It twitching of atrial musculature. It is the most common dysrhythmia is the most common dysrhythmia that causes patients to seek that causes patients to seek medical attention. It may start medical attention. It may start and stop suddenly and stop suddenly

Characteristics of Atrial Characteristics of Atrial FibrillationFibrillation

Ventricular and atrial rate: Atrial Ventricular and atrial rate: Atrial rate is 300 to 600. Ventricular rate is 300 to 600. Ventricular rate usually 120 to 200 in rate usually 120 to 200 in untreated atrial fibrillationuntreated atrial fibrillation

Ventricular and atrial rhythm: Ventricular and atrial rhythm: Highly IrregularHighly Irregular

QRS shape & duration: usually QRS shape & duration: usually normal, but may be abnormalnormal, but may be abnormal

P wave: no discernible P waves: P wave: no discernible P waves: Irregular undulating waves are Irregular undulating waves are seen and are referred to as seen and are referred to as fibrillatory or F wavesfibrillatory or F waves

PR interval: cannot be measuredPR interval: cannot be measured P: QRS ratio: many:1P: QRS ratio: many:1

Symptoms Symptoms

irregular palpitations, fatigue, irregular palpitations, fatigue, and malaiseand malaise

Treatment Treatment

Depends on its cause duration Depends on its cause duration and the patient’s symptom’s, and the patient’s symptom’s, age, and comorbiditiesage, and comorbidities

For Acute Onset For Acute Onset

Quinidine, ibutilide, flecanide, Quinidine, ibutilide, flecanide, dofetilide, propafenonedofetilide, propafenone

Procainamide (Pronestyl), Procainamide (Pronestyl), disopyramide,or amiodaronedisopyramide,or amiodarone

Junctional DysrhythmiasJunctional Dysrhythmias

Premature Junctional Complex – A Premature Junctional Complex – A premature junctional complex is premature junctional complex is an impulse that starts in the AV an impulse that starts in the AV nodal area before the next normal nodal area before the next normal sinus impulse reaches the AV sinus impulse reaches the AV node. Premature junctional node. Premature junctional complex include digitalis toxicity, complex include digitalis toxicity, congestive heart failure, and congestive heart failure, and coronary artery disease. coronary artery disease.

The ECG criteria for premature The ECG criteria for premature junctional complex are the same junctional complex are the same as for PAC’s, except for the P as for PAC’s, except for the P wave and the PR interval. The P wave and the PR interval. The P wave may be absent, may follow wave may be absent, may follow the QRS, or may occur before the the QRS, or may occur before the QRS but with a PR interval of less QRS but with a PR interval of less than 0.12 seconds. Premature than 0.12 seconds. Premature junctional complexes rarely junctional complexes rarely produce significant symptomsproduce significant symptoms

TreatmentTreatment

Same as for frequent PAC’sSame as for frequent PAC’s

Junctional Rhythm – Junctional Rhythm – Junctional or idional rhythm Junctional or idional rhythm occurs when the AV node, occurs when the AV node, instead of the sinus node instead of the sinus node slows (from increased vagal slows (from increased vagal tone) or when the impulse.tone) or when the impulse.

ECG criteria for junctional ECG criteria for junctional RhythmRhythm

Ventricular & atrial rate: Ventricular & atrial rate: ventricular rate 40 to 60: atrial ventricular rate 40 to 60: atrial rate also 40 to 60 if P waves are rate also 40 to 60 if P waves are discerniblediscernible

Ventricular and Atrial rhythm: Ventricular and Atrial rhythm: regularregular

QRS shape and duration: usually QRS shape and duration: usually normal but may be abnormal normal but may be abnormal

P wave: may be absent, after the P wave: may be absent, after the QRS complex, or before the QRS: QRS complex, or before the QRS: may be inverted, especially in may be inverted, especially in lead IIlead II

PR interval: If P wave is in front PR interval: If P wave is in front of the QRS, PR interval is less of the QRS, PR interval is less that 0.12 secondthat 0.12 second

P: QRS ratio: 1:1 or 0:1P: QRS ratio: 1:1 or 0:1

Atrioventricular nodal Reentry Atrioventricular nodal Reentry Tachycardia – AV nodal reentry Tachycardia – AV nodal reentry tachycardia occurs when an tachycardia occurs when an impulse is conducted to an area impulse is conducted to an area in the AV node that causes the in the AV node that causes the impulse to be revouted back into impulse to be revouted back into the same area over and over and the same area over and over and over again at very fast rate.over again at very fast rate.

Factors associated with the Factors associated with the development of AV nodal reentrydevelopment of AV nodal reentry caffeine, nicotine, hypoxemia caffeine, nicotine, hypoxemia

and stress and stress

ECG criteria ECG criteria

Ventricular & atrial rate: Atrial Ventricular & atrial rate: Atrial rate usually ranges between 150 rate usually ranges between 150 to 250 ventricular rate usually to 250 ventricular rate usually ranges between 75 to 250ranges between 75 to 250

Vetricular and atrial rhythm: Vetricular and atrial rhythm: regular: sudden onset regular: sudden onset termination of the tachycardiatermination of the tachycardia

QRS shape & duration: usually QRS shape & duration: usually normal, but may be abnormalnormal, but may be abnormal

P wave – usually very difficult to P wave – usually very difficult to discerndiscern

PR interval: If P wave is in front PR interval: If P wave is in front of the QRS, PR interval is lessof the QRS, PR interval is less

P: QRS ratio: 1:1, 2:1P: QRS ratio: 1:1, 2:1

Ventricular DysrhythmiasVentricular Dysrhythmias

Premature Ventricular Complex – Premature Ventricular Complex – Premature ventricular complex Premature ventricular complex (PVC) is an impulsive that starts (PVC) is an impulsive that starts in a ventricle and is conducted in a ventricle and is conducted through the ventricles before the through the ventricles before the next normal sinus impulse – PVCs next normal sinus impulse – PVCs can occur in healthy people, can occur in healthy people, especially with the use of especially with the use of caffeine, nicotine, or alcohol caffeine, nicotine, or alcohol

CausesCauses

Cardiac ischemia or infarction, Cardiac ischemia or infarction, increased workload on the heart increased workload on the heart (e.g. exercise, fever, (e.g. exercise, fever, hyperrolemia, heart failure, hyperrolemia, heart failure, tachycardia), digitalis toxicity, tachycardia), digitalis toxicity, hypoxia, acidosis or electrolyte hypoxia, acidosis or electrolyte imbalances, especially imbalances, especially hypokalemiahypokalemia

ECG characteristics of ECG characteristics of PVCPVC

Ventricular & atrial rate: Depends Ventricular & atrial rate: Depends on the underlying rhythm (e.g. on the underlying rhythm (e.g. sinus rhythm)sinus rhythm)

Ventricular & atrial rhtythm: Ventricular & atrial rhtythm: Irregular due to early QRS, Irregular due to early QRS, eveating one RR interval that is eveating one RR interval that is shorter than the others. PP shorter than the others. PP interval may be regular, indicating interval may be regular, indicating that the PVC did not depolarize that the PVC did not depolarize the sinus nodethe sinus node

QRS shape and Duration: QRS shape and Duration: Duration is 0.12 seconds or Duration is 0.12 seconds or longer shape is bizarre and longer shape is bizarre and AbnormalAbnormal

P wave visibility of P wave P wave visibility of P wave depends on the timing of the depends on the timing of the PVC: may be absent (hidden in PVC: may be absent (hidden in the QRS or T wave) or in front of the QRS or T wave) or in front of the QRSthe QRS

If the P wave follows the QRS, If the P wave follows the QRS, the shape of the P wave may the shape of the P wave may be differentbe different PR interval: If the P wave is in PR interval: If the P wave is in

front of the QRS, the PR front of the QRS, the PR interval is less than 0.12 interval is less than 0.12 secondsseconds

Causes Causes

Similar to those for PVCSimilar to those for PVC

QRS shape and duration: QRS shape and duration: Duration is 0.12 seconds or more Duration is 0.12 seconds or more bizarre; abnormal shapebizarre; abnormal shape

P wave: very difficult to detect, P wave: very difficult to detect, so atrial rate and rhythm may be so atrial rate and rhythm may be indeterminableindeterminable

Characteristics for VT Characteristics for VT

Ventricular and atrial rate: Ventricular and atrial rate: ventricular rate is 100 to 200 ventricular rate is 100 to 200 beats per minute: atrial rate beats per minute: atrial rate depends on the underlying depends on the underlying rhythm (e.g. sinus rhythm)rhythm (e.g. sinus rhythm)

Ventricular and atrial rhythm: Ventricular and atrial rhythm: usually regular; atrial rhythm usually regular; atrial rhythm may also be regularmay also be regular

PR interval: very irregular, if P PR interval: very irregular, if P waves seenwaves seen

P: QRS ratio: Difficult to P: QRS ratio: Difficult to determine, but if P waves are determine, but if P waves are apparent, there are usually more apparent, there are usually more QRS complexes than P wavesQRS complexes than P waves

P: QRS ratio: 0:1, 1:1P: QRS ratio: 0:1, 1:1 Ventricular Tachycardia – Ventricular Tachycardia –

ventricular tachycardia CVT) is ventricular tachycardia CVT) is defined as three or more PVC’s defined as three or more PVC’s in a row, occurring at a rate in a row, occurring at a rate exceeding 100 beats per exceeding 100 beats per minuteminute

Treatment Treatment

Immediate defibrillation for the Immediate defibrillation for the patient who is unconscious and patient who is unconscious and without a pulsewithout a pulse

Ventricular Fibrillation – Ventricular Fibrillation – Ventricular Fibrillation is a rapid Ventricular Fibrillation is a rapid but disorganized ventricular but disorganized ventricular thythm that causes ineffective thythm that causes ineffective quivering of the ventricles – quivering of the ventricles – theres in no atrial activity seen theres in no atrial activity seen the ECG the ECG

Causes Causes

Same as for VtSame as for Vt Electrical shock & brugada Electrical shock & brugada

syndromesyndrome

Characteristics of Characteristics of ventricular Fibrillationventricular Fibrillation

Ventricular rate: Greater than Ventricular rate: Greater than 300 per minute300 per minute

Ventricular rhythm: Extremely Ventricular rhythm: Extremely irregular, without specific patternirregular, without specific pattern

QRS shape and duration: QRS shape and duration: Irregular, undulating waves Irregular, undulating waves without recognizable QRS without recognizable QRS complexescomplexes

Treatment Treatment

immediate defibrillation and immediate defibrillation and activation of emergency servicesactivation of emergency services

Idioventricular Rhythm - Idioventricular Rhythm - Idioventricular Rhythm, also Idioventricular Rhythm, also called ventricular escape rhythm, called ventricular escape rhythm, occurs when the impulse starts occurs when the impulse starts in the conduction system below in the conduction system below the AV node. the AV node.

ECG criteria for ECG criteria for idioventricular rhythm idioventricular rhythm

Ventricular rate: ranges between Ventricular rate: ranges between 20 and 40; if the rate exceeds 40, 20 and 40; if the rate exceeds 40, the rhythm is known as the rhythm is known as accelerated idioventricular rhythm accelerated idioventricular rhythm CAIVR)CAIVR)

Ventricular rhythm: regularVentricular rhythm: regular

QRS shape & duration: Bizarre, QRS shape & duration: Bizarre, abnormal shape duration is 0.12 abnormal shape duration is 0.12 seconds or moreseconds or more

Ventricular Asystole – Commonly Ventricular Asystole – Commonly called flatline, ventricular called flatline, ventricular asystole is characterized by asystole is characterized by absent QRS complexes, although absent QRS complexes, although P waves may be apparent for a a P waves may be apparent for a a short duration in two different short duration in two different leads. There is no heartbeat, no leads. There is no heartbeat, no palpable pulse, and no palpable pulse, and no respirationrespiration

Causes Causes

hypoxia, acidosis, severe hypoxia, acidosis, severe electrolyte imbalance, drug electrolyte imbalance, drug overdose or hypothermiaoverdose or hypothermia

Treatment Treatment

Cardiopulmunary Resuscitation & Cardiopulmunary Resuscitation & emergency services are emergency services are necessary to keep the patient necessary to keep the patient alivealive

Conduction Abnormalities – When Conduction Abnormalities – When assessing the rhythm strip, the assessing the rhythm strip, the nurse takes first to identify the nurse takes first to identify the underlying rhythm (e.g. sinus underlying rhythm (e.g. sinus rhythm, sinus arrhythmia) Then rhythm, sinus arrhythmia) Then the PR interval is assessed for the the PR interval is assessed for the possibility of an AV block. AV possibility of an AV block. AV block occur when the conduction block occur when the conduction of the impulse through the AV of the impulse through the AV nodal area decreased or stopped. nodal area decreased or stopped.

First – degree Atrioventricular First – degree Atrioventricular Block – First degree heart block Block – First degree heart block occurs when all the atrial occurs when all the atrial impulses are conducted through impulses are conducted through the AV node into the ventricles at the AV node into the ventricles at a rate slower than normal a rate slower than normal

CausesCauses

hemodynamic effecthemodynamic effect Causing a decrease in perfusion Causing a decrease in perfusion

to vital organ, such as the brain, to vital organ, such as the brain, heart, kidneys, lungs, & skinheart, kidneys, lungs, & skin

Characteristics of First Characteristics of First degree degree

Ventricular and atrial rate: Ventricular and atrial rate: Depends on the underlying Depends on the underlying rhythmrhythm

Ventricular and atrial rhythm: Ventricular and atrial rhythm: Depends on the underlying Depends on the underlying rhythmrhythm

QRS shape and duration: usually QRS shape and duration: usually normal, but maay be abnormalnormal, but maay be abnormal

P wave: In front of the QRS P wave: In front of the QRS complex: shows sinus rhythm, complex: shows sinus rhythm, regular shaperegular shape

PR interval: Greater than 0.20 PR interval: Greater than 0.20 seconds: PR interval seconds: PR interval measurement is constantmeasurement is constant

P: QRS ratio 1:1P: QRS ratio 1:1

Second – degree atrioventricular Second – degree atrioventricular Block, type I – Second – degree, Block, type I – Second – degree, type I heart block occurs when type I heart block occurs when all but one of the atrial impulses all but one of the atrial impulses are conducted through the AV are conducted through the AV node into the ventricles. node into the ventricles.

Each atrial impulse takes a Each atrial impulse takes a longer time for conduction than longer time for conduction than the one before, until one impulse the one before, until one impulse is fully blocked. Atrial impulse, is fully blocked. Atrial impulse, the AV node has time to fully the AV node has time to fully repolarize, so that the next atrial repolarize, so that the next atrial impulse can be conducted within impulse can be conducted within the shortest amount of time. the shortest amount of time.

Characteristics of 2nd – Characteristics of 2nd – degree degree

Ventricular and atrial rate: Ventricular and atrial rate: Depends on the underlying rhythmDepends on the underlying rhythm

Ventricular and atrial rhythm: The Ventricular and atrial rhythm: The Pp interval is regular if the patient Pp interval is regular if the patient has an underlying normal sinus has an underlying normal sinus rhythm: the RR interval rhythm: the RR interval characteristically reflects a pattern characteristically reflects a pattern of change. Starting from the RR of change. Starting from the RR that is the longer, the RR interval that is the longer, the RR interval gradually shortens until there is gradually shortens until there is another long RR interval againanother long RR interval again

QRS shape & duration – usually QRS shape & duration – usually normal, but may be abnormalnormal, but may be abnormal

P wave: In front of the QRS P wave: In front of the QRS complex, shape depends in complex, shape depends in underlying rhythmunderlying rhythm

PR interval: PR interval becomes PR interval: PR interval becomes longer with each succeeding ECG longer with each succeeding ECG complex until there is a P wave complex until there is a P wave not followed by a QRS. The not followed by a QRS. The changes in the PR interval are changes in the PR interval are repeated between each “dropped” repeated between each “dropped” QRS, creating a pattern in the QRS, creating a pattern in the irregular PR interval irregular PR interval measurements.measurements.

P: QRS ratio: 3:2, 4:3, 5:4 and so P: QRS ratio: 3:2, 4:3, 5:4 and so forthforth

Second – Degree Alrioventicular Second – Degree Alrioventicular Block, Type II – Second – degree, Block, Type II – Second – degree, type II heart block occurs when type II heart block occurs when only some of the atrial impulses only some of the atrial impulses are conducted through the AV are conducted through the AV node into the ventricles.node into the ventricles.

Characteristics of 2nd Characteristics of 2nd degree Av block, type II degree Av block, type II

Ventricular & atrial rate: Depends Ventricular & atrial rate: Depends on the underlying rhythmon the underlying rhythm

Ventricular & atrial rhythm: The PP Ventricular & atrial rhythm: The PP interval is regular if the patient interval is regular if the patient has an underlying normal sinus has an underlying normal sinus rhythm. The RR interval is usually rhythm. The RR interval is usually regular but may be irregular, regular but may be irregular, depending on the P: QRS ratiodepending on the P: QRS ratio

QRS shape & duration: usually QRS shape & duration: usually abnormal, but may be normalabnormal, but may be normal

P wave: In front of the constant P wave: In front of the constant for those P waves just before for those P waves just before QRS complexesQRS complexes

P: QRS ratio: 2:1, 3:1, 4:1, 5:1, P: QRS ratio: 2:1, 3:1, 4:1, 5:1, and so forthand so forth

Third – Degree Atrioventicular Third – Degree Atrioventicular Block – Third degree heart block Block – Third degree heart block occurs when no atrial impulse is occurs when no atrial impulse is conducted through the AV node conducted through the AV node into the ventricles. In third – into the ventricles. In third – degree heart block, two impulses degree heart block, two impulses stimulate the heart: one stimulate the heart: one stimulates the ventricles, stimulates the ventricles, represented by the QRS complex, represented by the QRS complex, & one stimulates the atria, & one stimulates the atria, represented by the P wave. represented by the P wave.

P waves may be seen, but the P waves may be seen, but the atrial electrical activity is not atrial electrical activity is not conducted down into the conducted down into the ventricles to cause the QRS ventricles to cause the QRS complex, the ventricular complex, the ventricular electrical activity this is called AV electrical activity this is called AV dissociationdissociation

Characteristics of 3rd Characteristics of 3rd degree AV block degree AV block

Ventricular & atrial rate: Ventricular & atrial rate: Depends on the escape and Depends on the escape and underlying Rhythmunderlying Rhythm

Ventricular and atrial rhythm: Ventricular and atrial rhythm: The PP interval is regular & the The PP interval is regular & the RR interval is regular: however, RR interval is regular: however, the PP interval is not equal to the the PP interval is not equal to the RR intervalRR interval

QRS shape & duration: Depends QRS shape & duration: Depends on the escape rhythm; in on the escape rhythm; in junctional escape, QRS shape & junctional escape, QRS shape & duration are usually normal, and duration are usually normal, and inventricular escape, QRS shape inventricular escape, QRS shape & duration are usually abnormal& duration are usually abnormal

P wave: Depends on underlying P wave: Depends on underlying rhythmrhythm

PR interval: Very irregularPR interval: Very irregular P: QRS ratio: more P waves than P: QRS ratio: more P waves than

QRS complexesQRS complexes

TreatmentTreatment

directed toward increasing the directed toward increasing the heart rate to maintain a normal heart rate to maintain a normal cardiac ouputcardiac ouput

If the patient is stable and has no If the patient is stable and has no symptoms, treatment is symptoms, treatment is indicated other than decreasing indicated other than decreasing or evadicating causeor evadicating cause

If the patient does not respond to If the patient does not respond to atrophine or has an acute m1, atrophine or has an acute m1, transcutaneous pacing should be transcutaneous pacing should be staredstared

Pacemaker therapyPacemaker therapy

A pacemaker is an electronic A pacemaker is an electronic device that provides electrical device that provides electrical stimuli the heart. Pacemakers stimuli the heart. Pacemakers are usually used when a patient are usually used when a patient has a slower-than-normal has a slower-than-normal impulse formation or a impulse formation or a conduction disturbance that conduction disturbance that causes symptoms. causes symptoms.

They may also be used to control They may also be used to control some tachydysrhythmias that do some tachydysrhythmias that do not respond to medication not respond to medication therapy. Biventricular (both therapy. Biventricular (both ventricles) pacing may be used ventricles) pacing may be used to treat advanced heart failure to treat advanced heart failure that does not respond to that does not respond to medication therapy. medication therapy.

Pacemaker can be permanent or Pacemaker can be permanent or temporary. Permanent temporary. Permanent pacemakers are used most pacemakers are used most commonly for irreversible commonly for irreversible complete heart block. Temporary complete heart block. Temporary pacemaker are used to support pacemaker are used to support patients until they improve or patients until they improve or receive a permanent pacemaker.receive a permanent pacemaker.

Pacemaker design and Pacemaker design and types types

Pacemakers consist of two Pacemakers consist of two components:components: an electronic pulse generator- the an electronic pulse generator- the

generator contains the circuitry generator contains the circuitry and batteries that generate the and batteries that generate the rate  (measured in beats per rate  (measured in beats per minute) and the strength minute) and the strength (measured in milliamperes [mA] (measured in milliamperes [mA] of the electrical stimulus of the electrical stimulus delivered to the heart.delivered to the heart.

Pacemaker electrodes- convey Pacemaker electrodes- convey the heart’s electrical activity the heart’s electrical activity through a lead to the through a lead to the generator; the generator’s generator; the generator’s electrical response to the electrical response to the information received is then information received is then transmitted to the heart transmitted to the heart

Leads can be threaded through a Leads can be threaded through a major vein into the right ventricle major vein into the right ventricle (endocardial leads), or they can (endocardial leads), or they can be lightly sutured onto the be lightly sutured onto the outside of the heart and brought outside of the heart and brought through the chest wall during through the chest wall during open hear surgery (epicardial open hear surgery (epicardial wires) the epicardial wires are wires) the epicardial wires are always temporary and are always temporary and are removed by a gentle tug within a removed by a gentle tug within a few days after surgery. few days after surgery.

The endocardial leads may be The endocardial leads may be temporarily placed with temporarily placed with catheters through the femoral, catheters through the femoral, antecubital, brachial or jugular antecubital, brachial or jugular vein (transvenous wires), usually vein (transvenous wires), usually guided by fluoroscopy.guided by fluoroscopy.

The  endocardial leads also may The  endocardial leads also may be placed permanently, usually be placed permanently, usually through the external jugular through the external jugular vein, and connected to a vein, and connected to a permanent, which is usually permanent, which is usually implanted underneath the skin in implanted underneath the skin in sudcutaneous pocket in the sudcutaneous pocket in the pectoral region or below the pectoral region or below the clavicleclavicle

Permanent pacemaker Permanent pacemaker generators are insulated to generators are insulated to protect  against body moisture protect  against body moisture and warmth.  and warmth. 

Different energy sources for Different energy sources for permanent generators permanent generators

Mercury-zinc batteries Mercury-zinc batteries (which last 3 to (which last 3 to 4 years)4 years)

Lithum cell unit (up to 10 years)Lithum cell unit (up to 10 years)

Nuclear-powered sources such as Nuclear-powered sources such as plutonium 238 (up to 20 years)plutonium 238 (up to 20 years)

Some of the batteries are Some of the batteries are rechargeablerechargeable

This procedure is usually This procedure is usually performed with the patient performed with the patient receiving a local anesthetic. receiving a local anesthetic. Hospitalization of the patient is Hospitalization of the patient is needed for implantation or needed for implantation or battery replacementbattery replacement

Pacemaker generator Pacemaker generator functionsfunctions

Because of wide use of Because of wide use of pacemaker, a universal code has pacemaker, a universal code has been adopted to provide a been adopted to provide a means of safe communication means of safe communication about their function about their function

Complication of the pacemaker Complication of the pacemaker useuse Complication associated with Complication associated with

pacemaker relate to their pacemaker relate to their presence within the body, and presence within the body, and improper functioning. the improper functioning. the following complication may following complication may arise from a pacemaker: arise from a pacemaker:

Local infection at the entry site of Local infection at the entry site of the leads for temporary pacing, or the leads for temporary pacing, or at the subcutaneous site for at the subcutaneous site for permanent generator placement permanent generator placement

Bleeding and hematoma at the Bleeding and hematoma at the level entry sites for temporary level entry sites for temporary pacing, or at the subcutaneous site pacing, or at the subcutaneous site for permanent generator for permanent generator placementplacement

              

Hemothorax from puncture of Hemothorax from puncture of the subclavian vein or internal the subclavian vein or internal mammary arterymammary artery

Ventricular ectopy and Ventricular ectopy and tachycardia from irritation of the tachycardia from irritation of the ventricular wall by the ventricular wall by the endocardial electrode endocardial electrode 

Movement or dislocation of the Movement or dislocation of the lead placed transvenously lead placed transvenously (perforation of the myocardium)(perforation of the myocardium)

Phrenic nerve, diaphragmatic Phrenic nerve, diaphragmatic (hiccupping may be a sign of (hiccupping may be a sign of this), or a skeletal muscle this), or a skeletal muscle stimulation if the lead is stimulation if the lead is dislocated or if the delivered dislocated or if the delivered energy (mA) is a set high   energy (mA) is a set high   

Rarely, cardiac tamponade from Rarely, cardiac tamponade from bleeding resulting from removal bleeding resulting from removal of epicardial wires used for of epicardial wires used for temporary pacingtemporary pacing

    The ECG is monitored very The ECG is monitored very carefully to detect pacemaker carefully to detect pacemaker function, which can arise from function, which can arise from failure in one or more failure in one or more components of the pacing components of the pacing system,system,

A patient experiencing pace A patient experiencing pace maker malfunction may develop maker malfunction may develop signs and  symptoms of signs and  symptoms of decreased cardiac output. The decreased cardiac output. The degree to which these symptoms  degree to which these symptoms  become apparent depends on the become apparent depends on the severity of the malfunction, the severity of the malfunction, the patient’s level of dependency on patient’s level of dependency on the pacemaker, and the patient’s the pacemaker, and the patient’s underlying condition underlying condition

Pacemaker malfunction is Pacemaker malfunction is diagnosed by alalyzing the ECG diagnosed by alalyzing the ECG

Inhibition of permanent Inhibition of permanent pacemakers can occur with pacemakers can occur with exposure to strong exposure to strong electromagnetic fields electromagnetic fields (electromagnetic interference)(electromagnetic interference)

The metal of the pacemaker The metal of the pacemaker generator may trigger some generator may trigger some store and airport security alarm store and airport security alarm but these alarm systems will not but these alarm systems will not interfere with pacemaker interfere with pacemaker function function

Diagnosis Diagnosis

Risk for infection related to Risk for infection related to pacemaker lead or generator pacemaker lead or generator insertioninsertion

Risk for ineffective copingRisk for ineffective coping Deficient knowledge regarding Deficient knowledge regarding

self care programself care program

Nursing intervention Nursing intervention

Preventing infectionPreventing infection Promoting effective copingPromoting effective coping Promoting home and community Promoting home and community

based carebased care

Cardioversion and Cardioversion and DefibrillationDefibrillation

Cardioversion and defibrillation Cardioversion and defibrillation are treatments for are treatments for tachydysrhythmias. They are tachydysrhythmias. They are used to deliver an electrical used to deliver an electrical current to depolarize a critical current to depolarize a critical mass of myocardial cellsmass of myocardial cells

Difference of cardioversion Difference of cardioversion and defibrillation and defibrillation

Timing of the delivery of the Timing of the delivery of the electrical currentelectrical current

Defibrillation  is usually Defibrillation  is usually performed as an emergency performed as an emergency treatment treatment

Cardioversion is a planed Cardioversion is a planed procedureprocedure

       

Electrical current may be Electrical current may be delivered through paddles or delivered through paddles or conductor pads. Both paddles conductor pads. Both paddles may be placed on the front of the may be placed on the front of the chest, which is the standard chest, which is the standard paddle placement ,or  instead of paddle placement ,or  instead of paddles, defibrillator paddles, defibrillator multifunction conductor pads multifunction conductor pads may be used. may be used.

The pads, which contain a The pads, which contain a conductive medium, are placed in conductive medium, are placed in the same position as the paddles, the same position as the paddles, they are connected to the they are connected to the defibrillator and allow for hands-defibrillator and allow for hands-off defibrillation. This method off defibrillation. This method reduces the risk of touching the reduces the risk of touching the patient during the procedure and patient during the procedure and increases electrical safety increases electrical safety

When performing defibrillation or When performing defibrillation or cardioversion, the nurse shoud cardioversion, the nurse shoud

remember remember

Use multifunction conductor pads or Use multifunction conductor pads or paddles with a conducting agent paddles with a conducting agent between the paddles and the skinbetween the paddles and the skin

Place paddles or pads so that they do Place paddles or pads so that they do not touch the patients clothing or not touch the patients clothing or bed linen and are not near bed linen and are not near medication patches or direct oxygen medication patches or direct oxygen flow flow

If cardioverting, ensure that the If cardioverting, ensure that the monitor leads attached to the patient monitor leads attached to the patient and the defibrillator is in sync mode.and the defibrillator is in sync mode.

Do not charge the device until Do not charge the device until ready to shock; then keep thumbs ready to shock; then keep thumbs and fingers off the discharge and fingers off the discharge buttons until paddles or pads are buttons until paddles or pads are on the chest and ready to deliver on the chest and ready to deliver the electrical chargethe electrical charge

Exert 20 to 25 pounds of pressure Exert 20 to 25 pounds of pressure on the paddles to ensure good on the paddles to ensure good skin contact skin contact

Record the delivered energy and Record the delivered energy and the results (cardiac rhythm’ the results (cardiac rhythm’ pulsre)pulsre)

After the events is complete, After the events is complete, inspect the skin under the pads inspect the skin under the pads or paddles for burns; if any are or paddles for burns; if any are detected, consult with the detected, consult with the physician or a wound care nurse physician or a wound care nurse about treatmentabout treatment

Cardioversion Cardioversion

Involves the delivery of a Involves the delivery of a “timed” electrical current to “timed” electrical current to terminate a tachydysrhtythmia. terminate a tachydysrhtythmia. In cardioversion, the defibrillator In cardioversion, the defibrillator isaset to synchronize with the isaset to synchronize with the ECG on a cardiac monitor so that ECG on a cardiac monitor so that the electrical impulse discharges the electrical impulse discharges during ventricular depolarization during ventricular depolarization (QRS complex). (QRS complex).

The synchronization prevents the The synchronization prevents the discharge from occurring during discharge from occurring during the vulnerable period of the vulnerable period of repolarization  (t wave), which can repolarization  (t wave), which can result in VT or ventricular result in VT or ventricular fibrillation. When the synchronizer fibrillation. When the synchronizer is on, no electrical current will be is on, no electrical current will be delivered if the defibrillator does delivered if the defibrillator does not discern a QRS complex. not discern a QRS complex.

If the cardioversion is elective, If the cardioversion is elective, anticoagulation for a few weeks anticoagulation for a few weeks before cardioversion may be before cardioversion may be indicated.indicated.

Nursing intervention Nursing intervention

Digoxin is usually with held for Digoxin is usually with held for 48 hours before cardioversion to 48 hours before cardioversion to ensure the resemption of sinus ensure the resemption of sinus rhythm with normal conduction rhythm with normal conduction

The patient is structed not to eat The patient is structed not to eat or drink for at least 8 hours or drink for at least 8 hours before the procedurebefore the procedure

Gel covered paddles or Gel covered paddles or conductor pads are positioned conductor pads are positioned front and back front and back (anteroposteriorly) for (anteroposteriorly) for cardioversioncardioversion

Before cardioversion, the patient Before cardioversion, the patient receives intravenous sedation as receives intravenous sedation as well as an analgesic medication well as an analgesic medication or anesthesiaor anesthesia

Indication of a successful Indication of a successful response are cardioversion to response are cardioversion to sinus rhythm, adequate sinus rhythm, adequate peripheral pulses, and adequate peripheral pulses, and adequate blood pressure. Because of the blood pressure. Because of the sedation, airway patency must sedation, airway patency must be maintained and the patients be maintained and the patients state of consciousness assessed. state of consciousness assessed.

Vital signs and oxygen saturation Vital signs and oxygen saturation are monitored and recorded until are monitored and recorded until the patient is stable and covered the patient is stable and covered from sedation and affects of from sedation and affects of analgesic medication or analgesic medication or anesthesia. ECG monitoring is anesthesia. ECG monitoring is required during and after required during and after cardioversion.cardioversion.

Defibrillation Defibrillation

Is used in emergency situation as Is used in emergency situation as the treatment of choice for the treatment of choice for ventricular fibrillation and ventricular fibrillation and pulseless VT. Defibrillation pulseless VT. Defibrillation depolarize a critical mass of depolarize a critical mass of myocardial cells at once; when myocardial cells at once; when they repolarize, the sinus node they repolarize, the sinus node usually recaptures its role as the usually recaptures its role as the pacemaker. pacemaker.

The electrical voltage required to The electrical voltage required to defibrillate the heart is usually defibrillate the heart is usually greater than that required for greater than that required for cardioversion. If three cardioversion. If three defibrillations of increasing defibrillations of increasing voltage have been unsuccessful, voltage have been unsuccessful, cardiopulmonary resuscitation is cardiopulmonary resuscitation is initiated and advanced life initiated and advanced life support treatment are begun. support treatment are begun.

Treatment Treatment

Epinephrine or vasopressin may Epinephrine or vasopressin may make it easier to convert the make it easier to convert the dysrhthymia to a normal rhythm dysrhthymia to a normal rhythm with defibrillation. These drugs with defibrillation. These drugs increase cerebral and coronary increase cerebral and coronary artery blood flowartery blood flow

After medication is administered After medication is administered and one minute of cardio and one minute of cardio pulmonary resuscitation is pulmonary resuscitation is performed, defibrillation is again performed, defibrillation is again administeredadministered

Antiaarhytmic medications such Antiaarhytmic medications such as amiodarone (cordorone, as amiodarone (cordorone, paceron), lidocaine (xylocaine), paceron), lidocaine (xylocaine), magnesium, orprocainamide magnesium, orprocainamide (pronestyl) are given if (pronestyl) are given if ventricular dysrhythmia persistventricular dysrhythmia persist

Wolff-Parkinson-White Wolff-Parkinson-White PreexcitationPreexcitation

This diagram illustrates ECG waves and intervals as well as This diagram illustrates ECG waves and intervals as well as standard time and voltage measures on the ECG paper.standard time and voltage measures on the ECG paper.

Implantable cardioverter Implantable cardioverter defibrillator defibrillator

The implantable cardioverter The implantable cardioverter defibrillator (ICD) is device that defibrillator (ICD) is device that detects and terminates life detects and terminates life threatening episodes of VT or threatening episodes of VT or ventricular fibrillation in high risk ventricular fibrillation in high risk patients. patients.

Patients at high risk are those Patients at high risk are those who survived sudden cardiac who survived sudden cardiac death syndrome, usually caused death syndrome, usually caused by ventricular fibrillation, or have by ventricular fibrillation, or have experienced by symptomatic VT experienced by symptomatic VT (syncope secondary to VT), an (syncope secondary to VT), an ICD may be indicated for patients ICD may be indicated for patients who have survived an MI but are who have survived an MI but are at high risk for cardiac arrest.at high risk for cardiac arrest.

An ICD consist of a generator An ICD consist of a generator and at least one lead that can and at least one lead that can sense intrinsic electrical activity sense intrinsic electrical activity and deliver an electrical impulse. and deliver an electrical impulse. The device is usually implanted The device is usually implanted much like a pacemaker.much like a pacemaker.

ICD are designed to respond to ICD are designed to respond to two criteria:two criteria: A rate that exceeds a A rate that exceeds a

predetermined levelpredetermined level A change in the isoelectric line A change in the isoelectric line

segmentssegments

When a dysrhythmia occurs, rate When a dysrhythmia occurs, rate sensors take 5 to 10 seconds to sensors take 5 to 10 seconds to sense the dysrhthymia. Then the sense the dysrhthymia. Then the device takes several seconds to device takes several seconds to charge and deliver the charge and deliver the programmed charge through the programmed charge through the lead to the heart. Battery life is lead to the heart. Battery life is about 5 years but varies about 5 years but varies depending on the use of the ICD depending on the use of the ICD over time, the battery is checked over time, the battery is checked during follow up visits.during follow up visits.

Care for the patient with an Care for the patient with an ICD ICD

Avoid infection at the ICD Avoid infection at the ICD insertion siteinsertion site Observed incision site daily for Observed incision site daily for

redness, swelling, and heatredness, swelling, and heat Take temperature; report any Take temperature; report any

increase.increase. Avoid tight restrictive clothing Avoid tight restrictive clothing

that may cause friction over that may cause friction over the insertion sitethe insertion site

Adhere to activity restrictionAdhere to activity restriction Movement of arm may Movement of arm may

continue to be restricted until continue to be restricted until incision heals if the ICD was incision heals if the ICD was implanted in pectoral region implanted in pectoral region

Avoid heavy lifting Avoid heavy lifting Discuss safety of activities (eg. Discuss safety of activities (eg.

Driving) with physician Driving) with physician Avoid contact sportsAvoid contact sports

Electrophysiological Electrophysiological studiesstudies

An electrophysiological (EP) study An electrophysiological (EP) study is used to evaluate ant treat is used to evaluate ant treat various dysrhythmias that have various dysrhythmias that have caused cardiac arrest or significant caused cardiac arrest or significant symptoms, it also is indicated for symptoms, it also is indicated for patients with symptoms that patients with symptoms that suggest a dysrhythmia that has suggest a dysrhythmia that has gone undetected and undiagnosed gone undetected and undiagnosed by other methods. An EP study is by other methods. An EP study is used to used to

Identify the impulse formation and Identify the impulse formation and propagation through the cardiac propagation through the cardiac electrical conduction systemelectrical conduction system

Assess the function or dysfunction Assess the function or dysfunction of the SA and AV nodal areasof the SA and AV nodal areas

Identify the location (called Identify the location (called mapping) and mechanism mapping) and mechanism dysrthymogenic focidysrthymogenic foci

Assess the effectiveness of Assess the effectiveness of antaarhythmic medications and antaarhythmic medications and devices for the patient with a devices for the patient with a dysrhythmiadysrhythmia

Tear certain dysrhythmias Tear certain dysrhythmias through the destruction of the through the destruction of the causative cells (ablation)causative cells (ablation)

An EP procedure is a type of cardiac An EP procedure is a type of cardiac catheterization that is performed in a catheterization that is performed in a specially equipped cardiac specially equipped cardiac catheterization laboratory. The patients catheterization laboratory. The patients is awake but lightly sedated. Usually a is awake but lightly sedated. Usually a catheter with multiple electrodes is catheter with multiple electrodes is inserted through the femoral vein, inserted through the femoral vein, threaded through the inferior vena threaded through the inferior vena cava, and advanced into the vein cava, and advanced into the vein heart. The electrodes are positioned heart. The electrodes are positioned within the heart at specific locations.within the heart at specific locations.

The electrodes also allow the The electrodes also allow the clinicians to introduce a pacing clinicians to introduce a pacing stimulus to the intracardiac area stimulus to the intracardiac area at a precisely timed interval and at a precisely timed interval and rate, thereby stimulating the area rate, thereby stimulating the area (programmed stimulation). An (programmed stimulation). An area of the heart may be paced at area of the heart may be paced at a rate much faster than the a rate much faster than the normal rate of automaticity, the normal rate of automaticity, the heart at which impulses are heart at which impulses are spontaneously formedspontaneously formed

One of the main purpose of One of the main purpose of programmed stimulation is to programmed stimulation is to assess the ability of the area assess the ability of the area surrounding the electrode to surrounding the electrode to cause a reentry dysrhythmiacause a reentry dysrhythmia

Complications of an EP study are Complications of an EP study are the same as those can occur with the same as those can occur with cardiac catheterization. Because cardiac catheterization. Because an artery is not always used, an artery is not always used, there is a lower incidence of there is a lower incidence of vascular complications than with vascular complications than with other catheterization procedure other catheterization procedure is lowis low

Patients who are undergo an EP Patients who are undergo an EP study may be anxious about the study may be anxious about the procedure and about its outcomeprocedure and about its outcome

Patients need to know that the Patients need to know that the dysrhythmia may occur during dysrhythmia may occur during the procedure, but under very the procedure, but under very controlled circumstances. It often controlled circumstances. It often stops on its own. during the stops on its own. during the procedure, patients benefit from procedure, patients benefit from a calm, reassuring approacha calm, reassuring approach

Postprocedural care includes Postprocedural care includes restrictions of activity to promote restrictions of activity to promote hemostasis at the insertion site. hemostasis at the insertion site. To identify any complications To identify any complications and to ensure healing, the and to ensure healing, the patients vital signs and patients vital signs and appearance of the insertion site appearance of the insertion site are assessed frequentlyare assessed frequently

Cardiac conduction Cardiac conduction surgery surgery

Atrial tachycardias and ventricular Atrial tachycardias and ventricular tachycardias that do not respond to tachycardias that do not respond to medications and are not suitable medications and are not suitable for antitachycardia pacing may be for antitachycardia pacing may be treated by methods other than treated by methods other than medications and devices. Such medications and devices. Such methods include endocardial methods include endocardial isolation, endocardial resection and isolation, endocardial resection and ablation. An ICD may be used with ablation. An ICD may be used with these surgical interventions. these surgical interventions.

Endocardial isolation Endocardial isolation

Endocardial isolation involves Endocardial isolation involves making an incision into the making an incision into the endocardium that separates the endocardium that separates the area where the dysrhythmia area where the dysrhythmia originates from surrounding originates from surrounding endocardium. The edges of the endocardium. The edges of the incision are then sutured incision are then sutured together. The incision and its together. The incision and its resulting scar tissue prevent the resulting scar tissue prevent the dysrhythmia from affecting the dysrhythmia from affecting the whole heart.whole heart.

Endocardial resection Endocardial resection

In endocardial resection, the In endocardial resection, the origin of the dysrhythmia is origin of the dysrhythmia is identified, and that area of the identified, and that area of the endocardium is peeled away. No endocardium is peeled away. No reconstruction or repair is reconstruction or repair is necessarynecessary

Catheter ablation Catheter ablation therapytherapy

Catheter ablation destroys Catheter ablation destroys specific cells that are cause specific cells that are cause central conduction method of central conduction method of tachydysrhythmia. It is performed tachydysrhythmia. It is performed with or after an EP study. Usual with or after an EP study. Usual indications for ablation are AV indications for ablation are AV nodal reentry tachycardia, atrial nodal reentry tachycardia, atrial fibrillation or VT unresponsive to fibrillation or VT unresponsive to previous therapy ( or which the previous therapy ( or which the therapy producedsignificant side therapy producedsignificant side effects)effects)

Ablation is also indicated to Ablation is also indicated to eliminate accessory Av pathways eliminate accessory Av pathways or bypass tracts that exist 9n the or bypass tracts that exist 9n the heart of patients with preexcitation heart of patients with preexcitation syndrome such as Wolf-parkinson-syndrome such as Wolf-parkinson-white (WPW) syndrom. During white (WPW) syndrom. During normal embrayonic development, normal embrayonic development, all conections between the atrium all conections between the atrium and ventricles disappear, except and ventricles disappear, except for that between the AV node and for that between the AV node and the budle of his. the budle of his.

Ablation may be accomplished Ablation may be accomplished by three different methods:by three different methods: Radiofrequency ablation- most Radiofrequency ablation- most

often used method, which often used method, which involves placing a special involves placing a special catheter at or near the origin of catheter at or near the origin of the dysrhythmia.the dysrhythmia.

Cryoablation- involves placing a Cryoablation- involves placing a special probe, cooled to a special probe, cooled to a temperature- 60 degree C (-76 temperature- 60 degree C (-76 degree F), on the endocardium degree F), on the endocardium at the site of the dysrhythmia’s at the site of the dysrhythmia’s origin for two minutes. The origin for two minutes. The tissue freezes and its later tissue freezes and its later replaced by scar tissue, replaced by scar tissue, eliminating the origin eliminating the origin dysrhythmia.dysrhythmia.

Electrical ablation- a catheter is Electrical ablation- a catheter is placed at or near the origin of placed at or near the origin of the dysrhythmia, and one to four the dysrhythmia, and one to four shocks of 100 to 300 joules are shocks of 100 to 300 joules are administered through the administered through the catheter directly to the catheter directly to the endocardium and surrounding endocardium and surrounding tissue. The cardiac tissue burns tissue. The cardiac tissue burns and scars, thus eliminating the and scars, thus eliminating the source of the dysrhythmia source of the dysrhythmia

During the ablation procedure, During the ablation procedure, defibrillation pads, an automatic defibrillation pads, an automatic blood pressure cuff, and a pulse blood pressure cuff, and a pulse oximeter are used on the oximeter are used on the patient, and an indwelling patient, and an indwelling urinary catheter is inserted. The urinary catheter is inserted. The patient is given light sedation. patient is given light sedation.

An EP study performed and An EP study performed and attempts to induced the attempts to induced the dysrhythmia are made. The dysrhythmia are made. The ablation catheter is placed at the ablation catheter is placed at the origin of the dysrhythmia, and the origin of the dysrhythmia, and the ablation procedure is performed. ablation procedure is performed. Multiple ablation may be Multiple ablation may be necessary. Successful ablation is necessary. Successful ablation is achived when the dysrhythmia can achived when the dysrhythmia can no longer be induced.no longer be induced.

The patient is monitored for The patient is monitored for another 30-60 minutes and then another 30-60 minutes and then retested to ensure that the retested to ensure that the dysrhythmia will not recur dysrhythmia will not recur

Postprocedural care is similar to Postprocedural care is similar to that for an EP study, except that that for an EP study, except that the patient is monitored more the patient is monitored more closely, depending on the time closely, depending on the time needed for recovery from needed for recovery from sedation. sedation.

The electrocardiogram (ECG, EKG) is used extensively in the diagnosis of heart disease, from congenital heart disease in infants to myocardial infarction and myocarditis in adults. Several different types of electrocardiogram exist.

Atrioventricular block, EKG tracingAtrioventricular block, EKG tracing

This picture shows an ECG This picture shows an ECG (electrocardiogram, EKG) of a person (electrocardiogram, EKG) of a person with an abnormal rhythm (arrhythmia) with an abnormal rhythm (arrhythmia) called an atrioventricular (AV) block. P called an atrioventricular (AV) block. P waves show that the top of the heart waves show that the top of the heart received electrical activity. Each P wave received electrical activity. Each P wave is usually followed by the tall (QRS) is usually followed by the tall (QRS) waves. QRS waves reflect the electrical waves. QRS waves reflect the electrical activity that causes the heart to activity that causes the heart to contract. When a P wave is present and contract. When a P wave is present and not followed by a QRS wave (and heart not followed by a QRS wave (and heart contraction), there is an atrioventricular contraction), there is an atrioventricular block, and a very slow pulse (bra block, and a very slow pulse (bra

Normal heart rhythmNormal heart rhythm

An electrocardiogram (ECG) test measures the electrical activity of the heart. A normal resting heart rate is 60 - 100 beats per minute

BradycardiaBradycardia

Bradycardia heart rhythms are characterized by a slowness of the heartbeat, usually at a rate under 60 beats per minute (normal resting rate is 60 - 100 beats per minute).

Ventricular tachycardia is a rapid resting heart rate initiated within the ventricles, typically at 160 - 240 beats per minute (normal resting rate is 60 - 100 beats per minute).

The intrinsic conduction system sets the basic rhythm of the beating heart by generating impulses which stimulate the heart to contract

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