Repaired Complete Atrioventricular Septal Defect Patient With Late Bradyarrhythmia: Case Presentation by Matthias Greutmann, MD, FESC

Case Synopsis

We report the case of a patient with repaired atrioventricular septal defect (AVSD) and trisomy 21. He underwent surgical repair at the age of 12 years by dual patch technique. Three years later he had a second repair operation for residual ventricular septal defect and severe regurgitation of both atrioventricular (AV) valves. At the age of 17 years he had an episode of intra-atrial reentrant tachycardia (IART) for which he underwent direct current cardioversion and was commenced on amiodarone.

The patient also had severe autism and was nonverbal. Since the age of 17 years he was living in a special care home, spending every second weekend with his parents. His caregiver and parents felt that his quality of life was fairly good and he seemed happy in his day-to-day life.

At the age of 18 years he had a convulsive syncope, which was attributed to a seizure disorder. No further investigations were undertaken at that time.

At the age of 19 years the patient was transferred to adult care and was subsequently followed at our center. Owing to his autism disorder with the inability to cooperate, physical examination and advanced investigations such as, Holter ECG monitoring and echocardiography were challenging. Echocardiography revealed significant residual left AV valve regurgitation, low-normal left ventricular ejection fraction, and mild pulmonary hypertension. The further course remained stable apart from hyperthyroidism at the age of 21 years, which normalized after cessation of amiodarone. The patient remained active and participated in social activities within the special care home and his family.

At the age of 30 years he had two episodes of “collapse” within 2 months. The nature of these collapses could not be further delineated and subsequent assessment by a neurologist did not clarify the cause of the collapse, although neither cerebral imaging nor electroencephalogram could be obtained due to lack of cooperation. Clinical findings, echocardiography, and electrocardiogram had remained unchanged compared with previous investigations. The electrocardiogram showed sinus rhythm with typical left axis deviation and complete right bundle branch block with normal PR intervals ( Fig. 16.1, panel A ).

While intermittent high-degree AV block was considered in a differential diagnosis of the “collapse,” a decision was made against prophylactic pacemaker implantation at that time without ECG-symptom correlation. Three weeks later the patient was admitted to his local hospital with rapidly worsening exercise tolerance. At this time, he was found to be in complete AV block with slow ventricular escape rhythm at a rate of 25 beats per minute ( Fig. 16.1, panel B ).

The patient was transferred to our center and a temporary transvenous pacemaker was inserted. Transesophageal echocardiography demonstrated a persistent interatrial shunt with spontaneous right-to-left-shunting on bubble-contrast injection. Given the increased risk of paradoxical embolism with transvenous pacemaker leads in the setting of intracardiac shunts, it was decided to implant an epicardial dual-chamber pacemaker system ( Fig. 16.2 ). The postoperative course was complicated by hemodynamic instability and the need for reintubation but the patient finally made a good recovery after a long hospital stay. In the initial period after pacemaker implantation he continued to have short “spells,” manifesting as absences but never again fell or lost consciousness and his exercise capacity recovered to his usual level.

Given his autism, regular examinations including pacemaker interrogation remained challenging and, at times, impossible. Four years after pacemaker implantation the patient was referred for urgent assessment as he had shown unusual aggressive behavior and seemed to suffer from decreased exercise tolerance. An echocardiographic examination under general anesthesia was performed and revealed severe left AV valve regurgitation and moderately impaired left ventricular ejection fraction. More importantly, however, pacemaker interrogation surprisingly revealed unexpected loss of pacemaker battery voltage, only 5 months after the last pacemaker interrogation (Medtronic EnRhythm MRI). Owing to loss of battery voltage, the pacemaker had been automatically reprogrammed from DDD to VVI mode and hence loss of AV synchrony had occurred.

After extensive discussions with family and caregivers we opted for a stepwise approach with resolution of pacemaker issues first and then, AV valve repair, if needed. The patient underwent pacemaker box change with reprogramming to DDD mode, made a good recovery, and recovered rapidly to his normal exercise tolerance. Given the good quality of life thereafter, valve replacement was postponed and the patient remains under regular follow-up.