Transvenous Right Atrial and Left Ventricular Pacing after the Fontan Operation

Abstract

We report a case of long-term, successful, endocardial atrioventricular pacing in a 32-year-old man who had severe heart failure and ascites after having undergone a Fontan procedure for tricuspid atresia 9 years earlier. The patient was referred to our hospital for Fontan revision. However, electroanatomic mapping of the right atrium revealed viable tissue at the interatrial septum above the os of the coronary sinus, and it appeared that the left ventricle could be paced from a coronary sinus branch. Therefore, instead of Fontan revision, an endocardial atrioventricular pacemaker was implanted transvenously.

On 5-year follow-up, the patient remained in New York Heart Association functional class I and had not been readmitted to the hospital for congestive heart failure or arrhythmias. His atrial and ventricular leads continued to show excellent pacing and sensing results.

After a Fontan operation, loss of atrioventricular (AV) synchrony usually results in severe systemic AV valve regurgitation, ventricular failure, and congestive heart failure, with a poor outcome.¹ The case presented herein involves a patient who was referred to our hospital for Fontan revision. When electroanatomic mapping of the right atrium revealed viable tissue at the interatrial septum above the os of the coronary sinus, it appeared that the left ventricle could be paced from a coronary sinus branch. Therefore, instead of Fontan revision, an endocardial atrioventricular pacemaker was implanted transvenously. Treatment and outcome are discussed. This case is particularly unusual because of its 5-year follow-up results.

Case Report

In August 2001, a 32-year-old patient was referred to our institution for surgery. The patient had been born with tricuspid atresia, an atrial septal defect, and a small perimembranous ventricular septal defect. He received a Pott's shunt (side-to-side anastomosis between the descending aorta and the left pulmonary artery) at age 3 months. At 3 years of age, because of recurrent congestive heart failure due to an oversized shunt, he required pulmonary banding in order to protect the pulmonary circulation for future Fontan conversion. During childhood and adolescence, he remained in reasonably good health.

At age 23 years, the patient began to have increasing polycythemia and cyanosis. Heart catheterization confirmed the previous diagnosis and showed well-preserved hemodynamic values. The patient underwent a classic Fontan procedure and closure of the Pott's shunt. His cardiac condition improved substantially, with total resolution of the cyanosis; however, he developed atrial tachycardia with a rapid ventricular rate response. Amiodarone, atenolol, and digoxin were prescribed, which resulted in good control of his arrhythmias.

Two years later, the patient was readmitted with syncope and documented bradycardia, and implantation of an epicardial pacemaker was recommended. At that time, the treating physicians decided to place a ventricular epicardial system from a subxiphoid approach. Before the implantation, the patient's left ventricular systolic function and dimensions were normal, and no mitral regurgitation or intracardiac shunt was detected. During the next 7 years, the patient was admitted to the hospital several times for congestive heart failure with progressive left ventricular dysfunction and mitral regurgitation, as well as ascites, peripheral edema, and abnormal hepatocellular function. He was diagnosed with paroxysmal atrial flutter and fibrillation, and he was placed on long-term anticoagulation.

When the patient presented at our hospital at age 32, he had been referred to us for revision of his Fontan operation because of syncope and congestive heart failure. During a 72-hour monitoring period, no arrhythmias were documented. The pacemaker mode was VOO at a rate of 65 beats/min due to battery end-of-life, with retrograde conduction. Echocardiography showed left ventricular global hypokinesis, dimensions of 72 mm at end diastole and 59 mm at end systole, and a calculated ejection fraction of 0.30 to 0.35. Moderate-to-severe mitral regurgitation was also documented.

The patient underwent heart catheterization and electrophysiologic evaluation, which showed 100% V-wave pacing with slow retrograde conduction, a systolic V wave of 35 mmHg, a pulmonary artery pressure of 38/28 mmHg, and no intracardiac shunting. No ventricular tachycardia was induced. The patient had a poor AV conduction reserve (AV block at rates faster than 90 beats/min) during atrial pacing. The coronary sinus was cannulated from the right atrium, and left ventricular pacing was performed using an electrophysiology catheter.

Electroanatomic mapping of the right atrium revealed viable tissue at the interatrial septum, above the os of the coronary sinus (Fig. 1). This position was marked to guide atrial lead placement.

Fig. 1 Three-dimensional electroanatomic map identifies viable atrial myocardium (greenish-blue) in the interatrial septum.

During AV sequential pacing with an AV delay of 180 ms, the systolic V wave disappeared. The pulmonary capillary wedge pressure was 15 mmHg, the pulmonary artery pressure decreased to 27/14 mmHg, and the systolic arterial pressure increased from 95 to 120 mmHg.

After documentation of this significant acute hemodynamic improvement, from the left axillary approach, a bipolar lead (Model 2188-68, Medtronic Inc.; Minneapolis, Minn) was placed in the lateral vein (Fig. 2), resulting in excellent ventricular pacing. We placed a 2nd lead (model 4068-45, Medtronic) in the interatrial septum, immediately above the os of the coronary sinus (Fig. 2). A Kappa DR pulse generator (Medtronic) was used for AV sequential pacing. The pulse generator in the epigastric region was removed with the patient under local anesthesia and sedation. He remained on amiodarone, atenolol, and lisinopril, but diuretics were discontinued after a few days. Warfarin was initiated on the 2nd day after pacemaker implantation.

Fig. 2 Right anterior oblique (A) and left anterior oblique (B) angiographic projections show a lead in the anterolateral vein (epicardial left ventricular pacing), and a 2nd lead in the low atrial septum above the os of the coronary sinus.

The patient's edema and ascites resolved completely. Five years later, he remained in New York Heart Association functional class I, with no hospitalization for congestive heart failure or arrhythmias, and no thromboembolic complications (no anticoagulation was given after the first 3 months). He had a left ventricular end-diastolic dimension of 60 mm, an ejection fraction of 0.50, trivial mitral regurgitation, and a normal mitral inflow pattern. Atrial and ventricular leads showed excellent pacing and sensing thresholds.

Discussion

In cases of tricuspid atresia, the total venous return crosses a large atrial septal defect to the left side of the heart, producing severe cyanosis. In 1968, Fontan and Baudet² used a prosthetic conduit from the right atrial appendage to direct the systemic return to the pulmonary artery and then closed the atrial septal defect.

The reported incidence of AV block after the Fontan procedure is only 2% to 3%, but with sinus node dysfunction, atrial tachyarrhythmias (incidence, 20%–45%),³ and the use of antiarrhythmic drugs, the need for ventricular pacing progressively increases with time and can reach 16%.⁴

Because the Fontan operation excludes the right ventricle from the venous circulation, conventional placement of endocardial ventricular pacing leads is not possible. The overall rate of epicardial lead failure at 5 years is reported to be 17%, but atrial lead failure may be as high as 40%.⁵ In patients who have had multiple thoracotomies, the presence of scarring and adhesions makes implants more challenging and more likely to fail.

Atrial epicardial pacing requires a sternotomy or lateral thoracotomy, which can lead to recurrent or chronic left pleural effusion.^5,6 In patients with intact AV conduction, endocardial atrial pacing has better long-term results and fewer complications than does epicardial pacing.⁷ In patients who require dual-chamber pacing, 1 hybrid approach involves subxiphoid epicardial ventricular pacing and an endocardial atrial lead that is tunneled to the epigastric area. This approach also requires general anesthesia and longer hospitalization than does endocardial pacing.

As Warnes and coworkers first reported in 1986,⁸ the coronary sinus drainage remains accessible for left ventricular epicardial pacing when it has not been modified. If a total endocardial or a hybrid (endocardial/epicardial) approach is being considered, complete understanding of the relevant anatomy and physiology is extremely important. This knowledge is crucial, because some of the newer and more common modified Fontan procedures preclude later access to the right atrium or coronary sinus without the creation of a bidirectional or right-to-left shunt. Moreover, a residual right-to-left shunt would make the risk of systemic thromboembolic complications an important contraindication to these approaches.

We believe that, if possible, transesophageal echocardiography, magnetic resonance imaging, or both should be performed on all adults with corrected congenital heart disease. We usually perform a detailed hemodynamic and angiographic evaluation, as well as electroanatomic mapping of the right atrium, to identify areas of atrial tissue that are likely to have adequate sensing and capture thresholds, and to guide atrial lead placement. We document access to the coronary sinus from the right atrium, evaluate access to the right atrium from the SVC, and obtain an angiogram of the coronary sinus to document the presence of an accessible tributary for left ventricular lead placement.

Loss of AV synchrony and particularly atrial flutter are associated with severe AV valve regurgitation and left ventricular deterioration.⁹ These can markedly worsen arrhythmias and inferior vena cava stasis, resulting in hepatic congestion, ascites, thrombosis, and exudative enteropathy.¹⁰ Any of these complications may be considered an indication for cardiac transplantation¹¹ or for Fontan revision with total cavopulmonary connection and arrhythmia surgery.¹² Our case clearly illustrates the importance of restoring AV synchrony and chronotropic competence before substantial deterioration occurs, particularly if it can be accomplished by a minimally invasive and otherwise low-risk procedure.

A recent publication from Dodge-Khatami and colleagues¹³ concluded that dual-chamber pacing with res-toration of AV synchrony significantly improved single-ventricle hemodynamics and helped decompensated Fontan patients, in whom arrhythmias improved or disappeared, heart failure was controlled, and exercise tolerance increased.¹³

The Fontan operation increases the risk of thromboembolic complications, particularly systemic venous thrombosis, probably because of increased venous pressure, turbulence, the presence of prosthetic material, and potential protein C deficiency.^14,15 Long-term systemic anticoagulation has been recommended after a Fontan procedure, particularly during the 1st postoperative year, but its use remains controversial and there is no consensus with regard to type or duration of prophylactic therapy.^16,17 We believe such anticoagulation to be particularly important in the presence of multiple intracardiac pacing leads, and we start warfarin therapy after lead placement. We also believe that the increased risk of thrombosis and warfarin therapy compares favorably with the morbidity and mortality rates of a repeat thoracotomy for pacemaker implantation, and our approach could delay the need for Fontan revision or cardiac transplantation for many years.