Pacemaker

Question 1

Indications for a Pacemaker (9)

Answer 1

• Symptomatic bradycardia (heart blocks)
• Sinus node dysfunction
• AV node dysfunction
• Pacing for specific conditions (CABG)
• Cardiac transplantation
• Prevention and termination of dysrhythmias
• Long QT syndrome
• Pacing for hemodynamic -indications
• Cardiac resynchronization therapy

*Indications: slow heart rate for many reasons (junctional rhythms or complete heart block, long QT syndrome, etc.)
Pacemaker maintains a certain rate usually 80 bpm.

Question 2

Dual Chamber Pacemakers

aka AV sequential pacemaker

Answer 2

Dual chamber pacemakers use two leads, one lead is place in the right atrium and the other in the right ventricle.

The leads stimulate the atrium and ventricle sequentially mimicking normal cardiac function.

Depolarizing the ventricle contracting the ventricles.

Question 3

Dual Chamber Pacemaker Rhythm

Answer 3

Note classic LBBB appearance

Atrial spike before the p wave meaning the atrial pacemaker depolarized it then the ventricular pacemaker then the QRS causing a spike downwards.

Atrial kick

Question 4

Atrial Paced rhythm

Answer 4

pacemaker spike before the normal p wave

rhythm is regular

Question 5

Ventricular paced rhythm

Answer 5

pacemaker spike goes before the QRS

QRS: wide (>.10 sec)

no P waves/ no PRI

RHYTHM: normal

Question 6

DUAL-CHAMBER PACEMAKER RHYTHM

ATRIAL AND VENTRICULAR

Answer 6

Atrial pacemaker spike before p wave followed by
Ventricular pacemaker spike before QRS

p wave normal; produced by atrial pacemaker
pri: .20 sec
QRS: wide > .10 seconds; produced by ventricular pacemaker

Question 7

BI-VENTRICULAR PACEMAKER
aka
Cardiac resynchronization therapy (CRT)

Answer 7

Two spikes = classic bi-ventricular

3 leads, one for each ventricle and one for the right atrtium (lead is actually on the coronary sinus vein and not left ventricle)

Don’t place left bi-ventricular pacemakers in the left side of heart because it can cause even the smallest clot.

Question 8

Congenital Long QT syndrome

Answer 8

Seen mostly in young people, especially in young women (early 20’s)
Takes too long for the repolarization to occur. Like the refractory period never ends (so long), making you vulnerable to V-TAC

It’s a surgical procedure.

1. syncope
2. seizures
3. sudden death

Normal QT < 0.38

Question 9

Synchronous or Demand Pacemakers

Answer 9

Synchronous or demand pacemakers discharge only when the patient’s heart rate drops below the pacemaker’s base rate.

Question 10

Asynchronous Pacemakers

Answer 10

Asynchronous or FIXED-RATE pacemakers discharge at a pre-set rate regardless of the patient’s heart rate.

usually 70-80 bpm

Question 11

Failure to fire/pace

Answer 11

pacemaker spikes are absent.
No pacemaker site at all = no depolarization pattern.

Cause: dead battery, a disruption in the connecting wires, or improper programming

Question 12

Failure to Capture

Answer 12

Pacemaker spikes are present, but no P waves or QRS follows the spike.

Ventricular pacemakers = VVI
mostly seen

it can fire but doesn’t have enough joules to depolarize

*turning up pacemakers voltage often corrects this problem.
lead wires should be checked- a dislodged/ broken lead wire may cause this

Question 13

Failure to Sense

Answer 13

Pacemaker fires because it fails to detect the heart’s intrinsic beats, resulting in abnormal complexes.

VVI (ventricular pacemaker) followed by qrs THEN NATIVE RHYTHM then native rhythm then pacemaker site.
QRS followed by a pacemaker site means failure to sense.
Failure to sense can follow in the p, t, wave,..cant see the native depolarization