History
A 61-year-old man with a history of Ebstein’s anomaly, which initially went to had repaired in 1997; he then underwent tricuspid valve replacement with a 35-mm bioprosthesis in 2001. The initial surgery also involved an intraoperative ablation of an accessory pathway and right atrial maze procedure. For recurrent paroxysmal atrial fibrillation, he underwent a successful pulmonary vein isolation procedure in 2004. The electrophysiologic study performed at that time revealed severe sinus node dysfunction, but he remained asymptomatic. It was also noted that the tricuspid valve prosthesis was implanted proximal (atrial) to the coronary sinus.
Comments
It is not uncommon for the bioprosthetic valve to be sewn on the atrial aspect of the coronary sinus in repair of Ebstein’s anomaly. This is performed to avoid injury to the compact atrioventricular node.
Current Medications
The patient takes aldactone, furosemide (Lasix), warfarin, losartan (Cozaar), atorvastin (Lipitor), and aspirin.
Current Symptoms
More frequent spells of presyncope continued, but no frank syncope occurred. The patient also described infrequent tingling of the face and arm.
Physical Examination
Comments
No clinical evidence of overt right heart failure or systemic desaturation was found.
Laboratory Data
Electrocardiogram
Findings
Electrocardiography revealed marked sinus bradycardia with right bundle branch block and a ventricular rate of 45 bpm (Figure 9-1). A sinus arrhythmia is present, in addition to a premature atrial complex.
FIGURE 9-1
Chest Radiograph
Findings
A chest radiograph revealed a normal-sized heart with a prominent right ventricular contour (Figure 9-2) and clear lung fields. A bioprosthetic valve ring was evident.
Exercise Testing
The exercise test was a maximal test and was negative for ischemia. His exercise capacity was poor (5.5 metabolic equivalents), with a hypotensive response to exercise. In addition, a limited heart rate response of 81 bpm (peak), with frequent premature atrial and ventricular contractions (PACs and PVCs), was noted.
Echocardiogram
Findings
The echocardiogram showed normal left ventricular chamber size and systolic function, moderate right ventricular enlargement, and a moderate decrease in right ventricular systolic function. The patient had undergone 35-mm Carpentier-Edwards tricuspid prosthetic valve replacement. The mean gradient was 4 mm Hg at a heart rate of 42 bpm. Trace tricuspid regurgitation was noted. Mobile echodensity was seen in the right ventricle attached at the midventricular septum. The location and characteristics were suggestive of a residual chord.
Physiologic Tracings
Findings
Event monitor tracings showed atrial premature contractions in a bigeminal pattern; varying P wave morphologies, a 2-second pause after a supraventricular premature contraction, and a single premature ventricular contraction (Figure 9-3). High-grade atrioventricular block is noted with a 4.1-second pause.
Focused Clinical Questions and Discussion Points
Discussion
Epicardial lead placement is mandatory in certain scenarios—that is, intracardiac shunting, Glenn anastamosis (i.e., bidirectional cavopulmonary), or mechanical tricuspid valve. In this situation, we did not consider epicardial lead placement because a bioprosthetic valve can be ultimately crossed by conventional pacing leads. It is also important to note that in this population of patients who have undergone one or more cardiac operations, the epicardium has significant amounts of scar tissue that preclude effective long-term epicardial pacing. Epicardial pacing in children with virgin epicardial ventricular or atrial surfaces has better long-term lead performance.3
Question
Could single-chamber atrial lead placement provide sufficient pacing support?
Discussion
Despite event monitor tracing showing evidence of high-grade atrioventricular block, intraatrial block must be considered in these patients. Repair of Epstein’s anomaly often involve resection and plication of large areas of redundant atrial myocardium. This leaves significant scarring within the atrium, and functional or anatomic block from the sinus node to the atrioventricular node may be present. Atrioventricular nodal function can remain normal in patients seen to have high-grade atrioventricular block. To assess this properly, multiple atrial lead positions should be attempted, with pacing close to the atrioventricular node, ideally on the septum. If pacing close to the node shows no evidence of atrioventricular block, the diagnosis is intraatrial block and a ventricular lead potentially can be avoided. This feature of intraatrial conduction delay also can be seen after other congenital heart disease operations.
Question
Should a right ventricular lead be placed through the tricuspid prosthesis?
Discussion
Conceptually, it remains logical to avoid placing a lead through a bioprosthetic valve. Not infrequently, it is seen to negatively affect tricuspid valve integrity and function. Recently, however, a study looking at this particular question has shown that transvalvular device lead placement across bioprosthetic valves is not associated with an increased incidence of significant prosthetic tricuspid regurgitation. This, however, has to be balanced against the need for a repeat operation in patients with congenital disease who have undergone one or more operations in which mediastinal and pericardial fibrosis and adhesions make further operations much higher risk.2
Question
Is it appropriate to consider coronary sinus lead placement, despite the prosthetic valve being sewn on the atrial aspect of the coronary sinus?
Discussion
In this patient, to pace the ventricle, it was necessary to cross the tricuspid valve for right ventricular apical pacing or coronary sinus pacing. However, it was postulated that several inherent differences exist in coronary sinus lead placement versus right ventricular apical placement. Right ventricular dyssynchrony caused by right ventricular apical pacing can potentially aggravate tricuspid regurgitation. In addition, left ventricular pacing in the context of cardiac resynchronization therapy (CRT) has been noted to confer a beneficial effect on tricuspid regurgitation.1
It is important to recognize that the current coronary sinus leads are thinner and more pliable than conventional right apical pacing leads. This makes them more amenable to intercommissural placement and avoidance of the leaflet edges. Intracardiac echocardiography at the time of lead placement can aid in both apical and coronary sinus placement to avoid the leaf edges and place the lead between the commissures. It is also important to note that the coronary sinus leads are not subject to as much diastolic and systolic cardiac motion as right ventricular apical leads. Their position within the atrioventricular groove thus can reduce the potential for leaflet trauma. If this approach is adopted, acute monitoring of the results and tricuspid regurgitation with intracardiac echocardiography allows for confirmation of optimal lead placement.
Final Diagnosis
The final diagnosis was symptomatic sinus node and atrioventricular node dysfunction.
Plan of Action
Pacemaker insertion was recommended, with assessment of intraatrial delay through pacing at various sites within the right atrium.
Intervention
To avoid prosthetic valve dysfunction, we planned to sequentially attempt atrial lead–only pacing, intracardiac echocardiography-guided right ventricular pacing, or coronary sinus pacing. First, the possibility of intraatrial conduction block was considered, and therefore various atrial lead positions were tried to assess conduction across any possible intraatrial delay sites. No evidence of intraatrial conduction delay was found, and the atrial lead was placed with acceptable thresholds slightly inferior to the superior vena cava junction. Atrioventricular nodal function was tested and found to be poor, with Wenckebach occurring at pacing rates above 600 ms (90 bpm), confirming the absolute need for a ventricular lead. To examine the effect of passing a pacing lead through the tricuspid valve, intracardiac ultrasound images were obtained after inserting a pacemaker lead across the valve toward the right ventricular apex. This resulted in significant tricuspid regurgitation, as noted in Figure 9-4, A. Thus an alternative approach was taken in which a thin (5.7-French, EASYTRAK 2, Boston Scientific, Natick, Mass) pacing wire was specifically guided between the commissure of the anterior and posterior prosthetic tricuspid valve leaflets into the coronary sinus, located just distal to the prosthesis in the basilar segment of the right ventricle (Figures 9-5 and 9-6). Subsequent intracardiac imaging performed after all wires were pulled revealed a very satisfactory placement with no tricuspid regurgitation noted, as seen in Figure 9-4, B.
FIGURE 9-4
Outcome
Acutely, a dual-chamber permanent pacemaker was implanted, with no tricuspid regurgitation. At his 1-year follow-up, the patient reported complete resolution of all presyncopal symptoms and an excellent exercise tolerance—biking about 5 miles without notable limitation. There was no evidence of lead dislodgement in the chest radiograph, and transthoracic echocardiography demonstrated no prosthetic tricuspid valve dysfunction and specifically no tricuspid regurgitation. The mean gradient was unchanged at 3 mm Hg. The lead was easily seen going across the prosthesis and into the coronary sinus. Device thresholds were all stable.
FIGURE 9-5
This case is pertinent to a discussion of CRT, even though this patient did not require CRT. The issues faced in patients with a congenital cardiac anomaly are much different from those without and require a careful and thoughtful approach to best lead placement. In addition, many congenital anomalies may result in severe systemic ventricular dysfunction. Even if systemic ventricular dysfunction is not present at the time a cardiac implantable device is required for other reasons, consideration should be given to the potential advantages of systemic ventricular pacing and the disadvantages of any pacing technique that would increase ventricular dyssynchrony or worsen valvular function. In this case an alternative ventricular lead placement approach was taken as a result of worsening tricuspid regurgitation with the initial approach.
FIGURE 9-6
Selected References
1. Bleeker G.B., Schalij M.J., Nihoyannopoulos P. et al. Left ventricular dyssynchrony predicts right ventricular remodeling after cardiac resynchronization therapy. J Am Coll Cardiol. 2005;46:2264–2269.
2. Eleid M.F., Blauwet L.A., Cha Y.-M. et al. Bioprosthetic tricuspid valve regurgitation associated with pacemaker or defibrillator lead implantation. J Am Coll Cardiol. 2012;59:813–818.
3. McLeod C.J., Attenhofer Jost C.H., Warnes C.A. et al. Epicardial versus endocardial permanent pacing in congenital heart disease. J Interv Card Electrophysiol. 2010;28:235–243.
