Bradyarrhythmia’s, Pacemaker’s

& Complex DevicesDr Chris McAloon

Medical Student Teaching

Overview

Interpreting Bradyarrhythmia’s

Different types of Bradyarrhythmia’s

Pacemakers

Complex Devices

First Rule

“ Always look at the patient”

Conducting system

7

Heart Blocks

NSR

Sinus brady

SSS

Sinoatrial block

Sinus arrest

8

Heart Blocks 1st degree2nd degree

Mobitz Type 1Mobitz Type 22:1, 3:1 AVB

3rd degreeFascicular block - LAD, RAD, TFBLBBB, RBBBAF, Flutter

Reversible Causes of Slow Heart Rate

Drug therapy

Acute Myocardial Infarction

Hypothermia

Hypothyroidism

Athletic Heart

Vaso-vagal mechanisms

Complete AV Block

All patients with persistent or intermittent complete AV block should be paced unless there is a reversible cause Irrespective of symptoms

Reversible causes include recent inferior MI,

hypothyroidism and drugs

This includes patients with congenital CHB

If you are not going to pace, you really need to be able to justify that decision

Sinus Node Dysfunction

Inappropriate bradycardiaIntermittent – faintness / syncope Persistent – SOB / muscle fatigue / exhaustion

Associated atrial tachyarrhythmias / AV BlockIntermittent – palpitations / faintness / syncope

Persistent – SOB / muscle fatigue / exhaustion

Associated clinical syndromesEmbolicHeart Failure

The ‘ALS’ Approach

1. Is there electrical activity?

2. What is the ventricular (QRS) rate?

3. Is the QRS rhythm regular or irregular?

4. Is the QRS complex width normal or prolonged?

5. Is there atrial activity present?

6. Is the atrial activity related to ventricular activity, if so how?

The Heart Block System

1. Are the P waves associated with the QRS complex at all?

No = This is 3rd Degree Heart Block

Yes= Move to Question 2

Third Degree/ Complete Heart Block

The Heart Block System

2. Is there one P wave to one QRS, with a prolonged PR interval that is not progressing (in length)?

Yes= This is 1st Degree Heart block

No = Go to question 3

First Degree Heart Block

The Heart Block System

3. Is there progression in PR interval duration until there is a non-conducted P wave?

Yes= This is Wenckebach

No = Go to question 4

Mobitz Type 1/ Wenckebach

The Heart Block System

4. Therefore it must be Mobitz type 2

Mobitz type 2 difficult to explain P waves conducted normal PR interval There are P waves that are not conducted Not always a specific block

2:1 3:1 4:3

Mobitz Type 2

Mobitz 2 – 3:1 Block

AV Block

SA Slow Sinus Rate

AtrialTachy-

arrhythmias

Pacemaker’s

Pacing Indications

0%

20%

40%

60%

80%

100%

0-9 10-19 20-29 30-39 40-49 50-59 60-69 70-79 80-89 90-99 100+

age by decade

pe

rcen

tag

e o

f to

tal

CHB AF SSS Other

BPEG / HRUK National Database 2003 - 4

Paced Patients: Predominant ECG Indication

0%

20%

40%

60%

80%

100%

0-9 10-19 20-29 30-39 40-49 50-59 60-69 70-79 80-89 90-99 100+

decade

per

cen

tag

e o

f to

tal

syncope pre syncope other

BPEG / HRUK National Database 2003-4

Paced Patients: Predominant Presenting Symptom

Pacing Indications

AV Block

Complete Heart Block

Second degree AV block (High block or symptoms)

Reversible: Inferior MI, Hypothyroidism

Sinus Node Disease

Chronotropic Incompetence

If resting HR in day time <30

Atrial Fibrillation

Bradycardia

Bradycardia in presence drugs for uncontrolled Tachycardia

International Codes Pacemaker

First Letter = Chamber(s) being PACED (A,V,D)

Second Letter = Chamber(s) being SENSED

Third Letter= How the device RESPONDS to SENSED Event (Inhibits, Triggers, Dual (I+T))

Fourth Letter = Added feature e.g R = Rate Response

Pacemaker Basic’s

A Unipolar System

A Bipolar System

What is the PPM?

What is the PPM?

What is the PPM?

What is the PPM?

Electrodes -- Fixation Mechanism Passive Fixation Mechanism – Endocardial

Tined Finned

Canted/curved

Electrodes – Fixation Mechanism

Active Fixation Mechanism – Endocardial

Fixed screw

Extendible/retractable

Pacemaker Prescription

Re-establish stable heart rate

Restore AV synchrony

Achieve chronotropic competence

Achieve normal physiological activation

and timing

A lead if normal A function

V lead if actual / threatened AV HB

Rate modulation if slow

1% A Lead only55% A + V Leads (Dual Chamber) 44% V Lead only (mostly in AF)

V lead normally @ RV apex

A

V

Complex Devices

Complex Devices

What can be done?

What can be done?

Technology

Heart Failure and CRT

Cardiac resynchronization therapy Cardiac resynchronization therapy (CRT)(CRT) Applicable to ~1/3 of all symptomatic HF Applicable to ~1/3 of all symptomatic HF

patientspatients Improvement in long term survivalImprovement in long term survival

NICE indicationsNICE indications NYHA III/IV, Optimal medical therapyNYHA III/IV, Optimal medical therapy LVEF LVEF <<35%35% QRS QRS >> 120ms 120ms

However, 20-30% non responders However, 20-30% non responders to CRTto CRT

Heart failure common and disabling conditionHeart failure common and disabling conditionHeart failure common and disabling conditionHeart failure common and disabling condition

CARE-HF: CRT vs Medical Therapy - Primary End Point

Cleland, J. et al. N Engl J Med 2005;352:1539-1549

NICE Guidance 95 & 120

Global Heroes 2012: 10 mile run

Susan Filler was an avid runner 2007 survived Cardiac Arrest ARVD diagnosed & ICD implanted Completed Boise & Canada Ironman

Patrick Grayson 21 Long QT diagnosed at 11 At 12 Cardiac Arrest & ICD implanted Protection of ICD gave confidence to run February 2012 ran 1st marathon

Erin Clark 20 years ago SCA, diagnosed Long QT BB 1st, then implanted ICD. ICD gave confidence to be active as protection 1 year ago started running

What patients say about ICD

When I die will this keep shocking me? In my coffin?

One day I want to join my wife – how can I do that with an ICD?

Can I be comfortable at the end of my life? Will Deactivation hurt? Do I need surgery?Will I die immediately after the ICD is

deactivated? I feel like the bionic man – can I die with

this?

ESC GUIDANCE 2010 ‘It seems clear at this point that this device is in your best interest, but

you should know at some point if you become very ill from your heart disease or another process you developing the future, the burden of this device may outweigh its benefit. While that point is hopefully a long way off, you should know that turning off your defibrillator is an option.’

‘Now that we’ve established that you would not want resuscitation in the event your heart was to go into an abnormal pattern of beating, we should reconsider the role of yourdevice. In many ways it is also a form of resuscitation. Tell me your understanding of the device and let’s talk about how it fits into the larger goals for your medical care at this point.’

‘Clinicians may be concerned that withdrawing life-sustaining treatments such as CIED (ICD) therapies amounts to assisted suicide or euthanasia. However, two factors differentiate withdrawal of an unwanted therapy from assisted suicide and euthanasia: the intent of the clinician, and the cause of death. First, in withdrawing an unwanted therapy, the clinician’s intent is not to hasten the patient’s death, but rather, to remove a treatment that is perceived by the patient as a burden.’