Pacemaker implantation

Question 1

What are the three vein accesses and their disadvantages/advantages?

Answer 1

Subclavian vein: higher pneumothorax risk to its intrathoracic location, risk of subclavian crush, uses fluorscopy. Advantage: allows the lead to lie flat within the pocket, least lead angulation
Axillary vein: advantage can be accessed extrathoracially, big caliber vessel. Disadvantage: venogram is needed
Cephalic: advantage: only vein with no accompanying artery, superficial and easy access, does not require venogram. Disadvatage: small size, risk of placing the lead/device too laterally affecting arm mobility, risk of bleeding if transecting the vessel.

Question 2

Explain the steps for PPM implantation

Answer 2

1. IV antibiotics (Cefazolin or Vancomycin) are given 30 prior to the incision.
2. Patient position, prepping and draping.
3. Anatomic landmarks marked (suprasternal notch, clavicle, deltopectoral groove).
4. Local analgesia (Bupivacaine or lidocaine)
5. Pectoral skin incision is made.
6. Venous access
7. Guidewire insertion (guidewires shouwld be advanced into the IVC to avoid sheath advancement into the azygous vein, CS or arterial system). It can also lead to vascular perforation resulting in pneumothorax or perforation and cardiac tamponade.
8. Sheath insertion
9. RV lead implantation:
10. RA lead implantation:

Question 3

Explain how to distinguish a true RV apical lead position vs a CS lead position in different radiographic views.

Answer 3

RV apex position radiographically the end of the lead appears on the AP projection to be between the left border of the vertebral column and the cardiac apex. The lateral view is necessary to distinguish between apical position in which the lead tip points anterior and caudally. If the lead is posteriorly directed in the right ventricle or is on the posterior side of the heart (in the CS).
In the RAO view, the fat pad highlights the AV valve plane. If the lead in the CS the lead will track this plane. If the lead is in the RV it will have an orthogonal course to this radiographic view going towards the apex of the heart.
In the LAO view, a lead in the RV is coming towards the image intensifier. A lead in the CS will have a leftward trajectory.
In the AP view, the RV lead should have a gentle curve along the right atrium lateral wall and cross the TV into the ventricular apex.

https://www.charthealthcareacademy.com/post/do-you-see-what-i-see

Question 4

How to assess an optimal RA lead position at implant?

Answer 4

Rhythmic to-and-fro medial and lateral motion of the tip of the lead. In AP projection shows that the lead is medial or lateral and a lateral projection shows the lead to be anterior at approximately the same level as the RV lead in the apex.

Question 5

What is slew rate?

Answer 5

Change in voltage with time (dV/dt) of the intrinsic deflection. Usually it is most important in patients with borderline sensing voltages at implant. Some patients with an R wave of 3 mV and slow slew rate may have undersensing, and others with a normal slew rate may have adequate sensing.

Question 6

What is the current of injury?

Answer 6

Current of injury represent a small area of endocardium that reacts to the placement or fixating of the lead and it is seen on the ECG as an increase in the electrical potential immediately after the intrinsic deflection. This finding indicates good lead fixation/ good contact of the lead with the endocardium.

Question 7

What is the normal impedance range at implant?

Answer 7

300-1200 ohms

Question 8

What is the normal impedance range at implant for passive fixation leads?

Answer 8

300-1200 ohms

Question 9

Name a few indications for epicardial leads.

Answer 9

1. In patients undergoing cardiac surgery for another indication with placement of epicardial leads at the same time.
2. Patients with a prosthetic tricuspid valve (in order to protect the valve and technical difficulty), a congenital anomaly, or tricuspid valve atresia.
3. Patients with ventricular septal defects or patients with right-to-left shunts in whom the possibility for systemic embolization exists.

Question 10

What are the risks associated with persistent left sided SVC?

Answer 10

Advancing a lead into the persistent left sided SVC results in traversing the CS and entering the heart in the right atrium. This makes the ventricular access more difficult due to the angulation. To avoid the difficulties of the left sided SVC, the right subclavian vein should be used, or right sided implant should be preferred.

Question 11

How is a pacemaker implanted post Fontan procedure?

Answer 11

https://www.khanacademy.org/science/health-and-medicine/circulatory-system-diseases/cyanotic-heart-diseases/v/hypoplastic-left-heart-syndrome-and-norwood-glenn-fontan (explains Hypoplastic left heart syndrom and the Norwood-Sano, Glenn and Fontan procedures)

Post Fontan procedure there is no transvenous access for the RV lead implant, therefore a dual-chamber pacing implant is accomplished by placing an epicardial RV lead at the time of the surgery and subsequently placing an endocardial atrial lead and tunneling the two leads to a common pectoral position for attachment to a dual-chamber pacemaker.

Question 12

What are the considerations for a device implant post cardiac transplant?

Answer 12

Often after cardiac transplant the donor atrium can no longer receive stimuli from the native SA node, and that´s because of the suture line between the free wall of native and the donor atrium. After transplant the patient usually has two atrial rhythms, both of which can be visible on the ECG. Because normal AV conduction usually exists between the donor atrium and ventricle, atrial pacing is used to preserve AV synchrony and for rate modulation. The standard approach is to implant a dual-chamber device with a lead in the donor atrium and a lead in the ventricle.