Ventricular pacing leads

De Martino G, Orazi S, Bisignani G et al (2005) Safety and feasibility of coronary sinus left ventricular pacing leads extraction a preliminary report. J Interv Card Electrophysiol 13(l) 35-38... 

Fig. 1.1 An early transvenous ventricular pacing lead Elema 588 (Elema-Schonander, Solna, Sweden, later Siemens Elema, and now St Jude Medical). Left Central Terylene core, at least three stainless steel ribbon conductors and polyethylene insulation. Right The electrode was very large and there were no fixation devices. The lead was over 100 cm long to allow tunneling from the subclavicular region to the abdomen, where a connector was attached and the pulse generator buried. (Permission for use St Jude.)...

Lieberman R, Padeletti L, Schreuder J, et al. Ventricular pacing lead location alters systemic hemodynamics and left ventricular function in patients with and without reduced ejection fraction. J Am CoU Cardiol 2006 48 1634-41. 

An ICD may also appear in what is called a "biventricular" type that has a left ventricular pacing lead in addition. Biventricular ICDs treat certain types of congestive heart failure through synchronous left and right ventricular pacing (see Chapter 9 for more details regarding biventricular pacing). 

The CS drains venous blood from the heart into the right atrium. Many branches from the LV flow into the CS, including those from the lateral and posterior LV. Currently, it is there that a left ventricular pacing lead is optimally placed. This maybe best visualized under fluoroscopy from a left anterior oblique (LAO) perspective. Many patients who are candidates to receive a CS left ventricular lead, however, have had myocardial infarctions that may limit the ability to pace from these sites. Stimulation of the left phrenic nerve during ventricular pacing may occur, and can preclude placement there (the left phrenic nerve travels in close proximity to this cardiac region on its way to the left hemi-diaphragm). 

The thresholds of right and left ventricular pacing leads can be difficult to assess in ICDs that do not have separate programmability for each output. This is because the morphology change of the QRS complex on a single surface ECG rhythm strip can be very subtle when capture is lost in a ventricular chamber. Also, since many of the patients for which a CRT device has been implanted have a native left bundle branch block (LBBB) pattern on their surface ECG, the RV capture and native QRS complexes can look remarkably similar. 

Daubert JC, Ritter P, Le Breton H, et al. Permanent left ventricular pacing with transvenous leads inserted into the coronary veins. Pacing Clin. Electrophysiol. 1998 21 239 5. 

Hua W, Mond HG, Strathmore N. Chronic steroid-eluting lead performance a comparison of atrial and ventricular pacing. Pacing and Clinical Electrophysiology 1997, 20, 17-24. 

Coronary venous lead connectors were initially developed to accommodate patients with heart failure who were previously implanted for other reasons and were considered eligible for an upgrade to biventricular pacing. For these patients, the ventricular output of the PM generator was divided via a Y connector from one bipolar output to two separate outputs - one for the previously implanted RV lead and the other for the new left ventricular (LV) lead. 

Fig. 2 J Transesophageal echocardiographic view of the right atrium and the right ventricle. There is an oblong mobile vegetation adherent to the pacing lead as it crosses the tricuspid valve attached to its ventricular portion. Patient had positive blood cultures for Staphylococcus lugdunensis. Both these findings are major criteria for the diagnosis of lead endocarditis...

TLR, transvenous lead removal A, atrial RV, right ventricular LV, left ventricular PL, pacing leads ICD, implantable cardioverter defibrillator L, leads... 

Similar results were shown by the European multicenter experience [23]. Kennergren et al. published the final report of the Pacing Lead Extraction Surveillance Study in Europe (PLESSE) trial in 2007 [24]. From August 1996 to March 2001, 383 leads (170 atrial, 213 ventricular mean implant time 74 months) implanted in 292 patients (mean age 61.6 years range 13-96) were extracted at 14 European centers. Complete extraction was achieved in 90.9% of leads and partial extraction in 3.4% extraction failed in 5.7%. Median extraction time was 15 min. Total complication rate, including five minor complications (1.7%), was 5.1%. Cardiac tamponade occurred in ten cases, but no in-hospital mortality occurred. 

Fig. 1.11 Twelve lead ECGs demonstrating bipolar and unipolar atrial and ventricular pacing. With unipolar pacing, there are prominent atrial and ventricular pacing spikes (stimulus artifact).

Fig. 1.28 Bipolar single pass lead for atrial sensing and ventricular pacing. (Permission for use Medtronic.)...

Fig. 3.11 Intrinsic cardiac depolarization can be recorded at the pacing lead electrode and measured by the pacemaker. This signal is called an electrogram. In this example, the electrogram is measured from the ventricular lead and is caused by ventricular depolarization. The signal has an amplitude of 8mV. This signal would not be seen by the pacemaker if the sensitivity is set to 10 mV. However, by lowering the sensitivity value to 5 mV (making the pacemaker more sensitive), the intrinsic depolarization would be seen and pacemaker timing cycles would be reset when appropriate.

Fig. 3.23 Pacemaker mediated tachycardia (PMT). In this case, a premature ventricular contraction (second QRS complex) leads to retrograde ventriculo-atrial (VA) conduction. The atrial activity occurs after the PVARP has expired, is sensed, and leads to ventricular pacing, which again is associated with VA conduction. An incessant tachycardia can be initiated and sustained in this way.

Fig. 3.25 Ventricular-based timing DDD lower rate behavior. The atrial escape interval (AEI) is initiated after a ventricular-paced or sensed event. Ventricular based timing leads to slightly faster heart rates if native conduction is present. In this example, the LRL is set to 60bpm, so the AEI is 800 ms for an AVI of 200ms.

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