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Atrial RhythmsAtrial Rhythms
Electrical impulses that originate from the atrium (not from the SA node).
Wandering Atrial Pacemaker Wandering Atrial Pacemaker (WAP)(WAP)
Rhythm: Slightly Irregular
Rate: Usually 60 – 100 bpm; sometimes slower
P waves: Morphology of each P wave differs
PRI: 0.12 – 0.20 sec; inconsistent
QRS: Narrow (< 0.12 sec); sometimes wide
Wandering Atrial Pacemaker Wandering Atrial Pacemaker (WAP)(WAP)
Causes:
Increased vagal effect on the sinoatrial node, slowing the sinus rate and allowing other pacemaker sites an opportunity to compete for control of the heart rate
It is a normal phenomenon in young healthy hearts (especially those of athletes)
Coughing may decrease vagal tone and encourage reappearance of a sinus rhythm
Premature Atrial Contraction (PAC) Premature Atrial Contraction (PAC)
A premature atrial contraction (PAC) is an early beat that occurs when an ectopic site within the atria discharges
an impulse before the sinus node impulse is discharged.
Ectopic site is speeding up in an attempt to take over as the pacemaker – irritability; (or the SA node has slowed
down)
Can originate from one ectopic site or from multiple sites in the atria.
PAC PAC If the ectopic site is near the SA node, the
appearance of the P wave may closely resemble the sinus P wave
Most often the P wave morphology of the PAC is significantly different from that of the sinus P
wave
Sometimes with very premature PAC’s, the P wave is hidden within the T wave of the
previous complex
PAC with Aberrant PAC with Aberrant Ventricular ConductionVentricular Conduction
PAC with Aberrant Ventricular Conduction
An early beat from an atrial site (other than the SA node) that is abnormally conducted
through the ventricles
Causes a change in the morphology of the QRS complex
(Example on p. 96)
Non-Conducted PACNon-Conducted PAC
P wave of PAC is not followed by a QRS complex
AV node is refractory and is unable to respond to the electrical stimulus
P wave is followed by a pause
P wave may be hidden in the T wave (changes morphology of the T wave) - May be confused with a block/arrest
(example on p. 99)
Compensatory vs. Compensatory vs. NoncompensatoryNoncompensatory
PAC’s are followed by a pause
What makes it compensatory versus noncompensatory???
(Overhead slide 3-1)
Premature Atrial Contraction Premature Atrial Contraction (PAC)(PAC)
Rhythm: Depends on the underlying rhythm; Premature ectopic beat causes slight irregularity
Rate: Overall HR depends on rate of underlying rhythm
P waves: P wave of premature beat will have a different morphology (flattened, notched, or unusual). May be hidden in
the T wave
PRI: 0.12 – 0.20 sec on regular beat; ectopic beat PRI may differ.
QRS: Narrow (< 0.12 sec); sometimes wide
Supraventricular TachycardiaSupraventricular Tachycardia(Paroxysmal Atrial Tachycardia)(Paroxysmal Atrial Tachycardia)
May occur as a basic rhythm or within an underlying rhythm (burst of SVT or PAT)
3 or more consecutive PAC’s with a rate of 140 – 250 is considered to be a burst of SVT or PAT
(example on p. 100)
Supraventricular TachycardiaSupraventricular Tachycardia(Paroxysmal Atrial Tachycardia)(Paroxysmal Atrial Tachycardia)
SVT/PAT may be a result of emotional stress, ingestion of caffeine, tobacco, or alcohol
Other causes:
COPD
Digitalis Toxicity
Supraventricular TachycardiaSupraventricular Tachycardia(Paroxysmal Atrial Tachycardia)(Paroxysmal Atrial Tachycardia)
During episodes of SVT/PAT, patient may experience the following s/s:
Hypotension
Decreased LOC
Palpitations
Chest Pain
S.O.B.
Supraventricular TachycardiaSupraventricular Tachycardia(Paroxysmal Atrial Tachycardia)(Paroxysmal Atrial Tachycardia)
Treatment involves controlling the ventricular rate in order to maintain adequate CO
Vagal Maneuvers
Adenosine, BB’s, CCB’s, digitalis
Antiarrhythmics (amiodarone)
IV Fluid Bolus
Electrical Cardioversion
SVT or PATSVT or PAT
Rhythm: Regular
Rate: 150 – 250 bpm
P waves: None (May be hidden in T wave); If present will have abnormal appearance
PRI: None or normal if P wave is present
QRS: Narrow (< 0.12 sec); sometimes wide
Atrial FlutterAtrial Flutter
Begins from one specific foci in the atrium. These atrial contractions are less rapid and more organized (than a-
fib) resulting in an atrial rate of 250 – 400 (Davis, 2004), (Huff, 2006)
Rapid stimulation/depolarization of the atrial muscles causes production of waveforms that resemble the
teeth of a saw
The sawtooth deflections are known as Flutter Waves
Atrial FlutterAtrial Flutter
Sometimes the flutter waves have a softer appearance and appear as “clouds”
(Example on p. 112, Strip 7-16)
Atrial firing is continuous; does not stop while impulses are traveling through the ventricles
Ventricular rate is controlled by AV node (the gatekeeper)
Atrial FlutterAtrial Flutter
Conducted by ratios (example above: every 3rd
impulse is conducted = 3:1 AV conduction)
Sometimes the ratio is not constant = variable AV conduction
(example on p. 103, Figure 7-18)
Atrial Flutter with Varied Atrial Flutter with Varied ResponseResponse
Atrial FlutterAtrial Flutter
If ventricular heart rate is less than 100 =
Controlled A-flutter
or
A-flutter with controlled ventricular response
Atrial FlutterAtrial Flutter
If ventricular heart rate is greater than 100 =
Uncontrolled A-flutter
or
A-flutter with RVR (rapid ventricular response)
Atrial FlutterAtrial Flutter
3:1 ResponseRhythm: Regular or irregular; depends on ventricular
response
Rate: Atrial 250 – 400 bpm; ventricular rate depends on AV conduction
P waves: Sawtooth/Cloud appearance
PRI: Unable to be measured
QRS: Narrow (< 0.12 sec); sometimes wide
Atrial FibrillationAtrial Fibrillation
It is the most common rhythm next to sinus rhythm
Is a result of various ectopic sites within the atria that are firing at a rate
of 400 – 600 bpm
Atrial FibrillationAtrial Fibrillation
Rapid depolarization of various sites causes the atria to quiver =
fibrillatory waveforms
Some of the atrial firing does not go to the AV node; remains in the same
place and only depolarizes that small area
Atrial FibrillationAtrial Fibrillation
Fib-Flutter waves
Flutter waves mixed with fibrillatory waves between the
QRS complexes
(Example on p. 111, Strip 7-14)
Atrial FibrillationAtrial FibrillationMay produce fine fibrillatory waves or
coarse fibrillatory waves
Coarse fibrillatory waves are “very wavy”
Fine waves are so small that they may appear as flat lines between the QRS’s
(example on p. 105, Figure 7-22)
Atrial FibrillationAtrial Fibrillation
Atrial firing is continuous; does not stop while impulses are traveling through the
ventricles
Ventricular rate is controlled by AV node (the gatekeeper)
Goal is to control the AV conduction to the ventricles
Atrial FibrillationAtrial Fibrillation
If ventricular heart rate is less than 100 =
Controlled A-fib
or
A-fib with controlled ventricular response)
Atrial FibrillationAtrial Fibrillation
If ventricular heart rate is greater than 100 =
Uncontrolled A-fib
or
A-fib with RVR (rapid ventricular response)
Atrial FibrillationAtrial Fibrillation
Rhythm: Irregular
Rate: Unable to measure atrial; ventricular depends on AV conduction
P waves: Fibrillatory waves (coarse or fine); chaotic
PRI: Unable to be measured
QRS: Narrow (< 0.12 sec); sometimes wide
A-Fib & A-FlutterA-Fib & A-FlutterCommon Causes:
Valvular Heart Disease (especially with mitral valve)
Hypertensive Heart Disease
CAD
Pulmonary Emboli
Hyperthyroidism
S/P Cardiac Surgery
A-Flutter & A-FibA-Flutter & A-FibTreatment involves converting the rhythm
and/or controlling the ventricular rate in order to maintain adequate CO, in
addition to prevention of blood clots
BB’s, CCB’s, digitalis
Antiarrhythmics (amiodarone)
IV Fluid Bolus
Anticoagulants
Electrical Cardioversion
A-Fib with controlled ventricular response
Rate:Rhythm: P wave:
QRS:
Approx. 90 bpmIrregular
None0.04 sec
Analyze the Following:
TIME TO WORKOUT!!!TIME TO WORKOUT!!!
ReferencesReferencesChernecky, C., et al. (2002). Real world nursing survival guide:
ECG’s & the heart. United States of America: W. B. Saunders Company.
Huff, J. (2006). ECG workout: Exercises in arrhythmia interpretation (5th ed.). United States of America: Lippincott, Williams & Wilkins.
Walraven, G. (1999). Basic arrhythmias (5th ed.). United States of America: Prentice-Hall, Inc.
www.madsci.com/manu/ekg_rhy.htm