Case Report. The patient is a 33-year-old male with a history of CCTGA who had a ventricular septal defect repair at 6 years of age, and had residual pulmonary stenosis, but had subsequently done very well and considered himself healthy. He had been powerlifting up to 312 lbs on the bench press and felt no physical limitations. For the past few weeks, he noticed easy fatigability and occasional palpitation, which he attributed to a cold. The patient was not on any medication and there was no history of smoking, alcohol or drug abuse. On the day of admission, he complained of shortness of breath while playing tennis and suddenly became unresponsive. The playing partner attempted bystander cardiopulmonary resuscitation. On arrival of the emergency medical services, he was found to be having pulseless VT and agonal respiration. The patient was defibrillated three times on site and managed subsequently with bag-mask ventilation. A lidocaine infusion was started en route to the hospital, where he required intubation and mechanical ventilation. On physical examination, he was an obese male with a baseline heart rate of 110 per minute and blood pressure of 126/82. He was acyanotic without thrills over the precordium, suprasternal notch or carotid arteries. He did not have jugular venous distension. S1 and S2 were normal without splitting. He had a 2/6 midsystolic ejection murmur heard best at the mid-left sternal border. There was no brachiofemoral delay, and his lungs were clear on auscultation. Abdominal examination did not reveal ascites or organomegaly, and there was no peripheral edema. A chest X-ray showed slight cardiomegaly and aspiration pneumonia that was treated with antibiotics. Electrocardiography (ECG) showed biatrial enlargement, nonspecific ST-T wave changes, nonspecific intraventricular conduction delay, QRS duration of 110 msec and a corrected QT-interval of 448 msec. Laboratory data showed a white cell count of 13,000, hemoglobin of 15, normal renal and liver function, potassium of 3.6, mg 2.2 and negative serial cardiac enzymes. The patient had a poor acoustic window on transthoracic echocardiography. Transesophageal echocardiography showed an L-TGA (congenitally corrected) pattern, mild mitral valve insufficiency (right-sided AV valve), mild-to-moderate TV insufficiency (systemic AV valve), mild left atrial enlargement, trace AV insufficiency, mild pulmonic stenosis (peak gradient of 15 mmHG), normal RV systolic function and no residual ventricular septal defect (VSD). Patient was monitored in CCU. Lidocaine was discontinued after 48 hours. The patient did not have any further episodes of sustained VT, however, during his stay, he continued to have brief runs of nonsustained VT, despite normal electrolytes and the absence of CHF. Coronary angiography showed nonobstructive coronary artery disease. Interestingly, he had a single coronary ostium giving rise to right and left coronary systems. (Figures 1 and 2).
The patient underwent implantable cardioverter-defibrillator (ICD) implantation with the placement of a screw in the transvenous ventricular lead in the systemic venous ventricle. ICD testing was performed by inducing ventricular fibrillation twice by the T-wave shock method, which was detected and treated successfully by ICD with 20 joules of energy. The patient was discharged in clinically stable condition. During the 6-month follow-up period, the patient had experienced no episodes of symptomatic VT.
Discussion. CCTGA has the highest mortality among all CHD patients. SCD is the most common cause of death in patients with CHD.8 SCD has been attributed to the presence of complete AV block or a rapid progression from first-degree AV block to complete AV block.9–11 Very rarely in a patient with CCTGA, VT has been attributed to the cause of SCD.6 In our patient, unlike the majority of patients with CCTGA, AV conduction was normal. Although the mechanism of VT in patients with CCTGA is uncertain, results of programmed ventricular stimulation suggest that the mechanism is likely related to reentry or automaticity. We report a very rare case of a patient who presented with pulseless VT leading to syncope as a risk of SCD. To our knowledge, there are only three documented cases of VT in a patient with CCTGA in the literature.6,12,13 First, a 29-year-old female with isolated CCTGA presented with a wide, complex tachycardia of 220 rates/min. An electrophysiology (EP) study confirmed HIS-bundle tachycardia. She was successfully treated with amiodarone.12 Second, a 49-year-old male developed syncope while exercising. VF was documented, and the patient was resuscitated and found to have CCTGA on magnetic resonance imaging. An EP study showed normal AV conduction and monomorphic VT that was easily induced with double extrastimuli. The patient was treated with sotalol.13 Third, a 31-year-old male with CCTGA and pulmonary stenosis presented with syncope. The patient was found to have easily inducible monomorphic and polymorphic VT that was treated with ICD placement.6 Several points are worth highlighting here. Patients with an anatomical systemic RV are at significant risk (22%) for heart failure,14 as the ventricle was not meant to take the systemic load developmentally. Graham et al15 concluded that after childhood, systemic ventricular dysfunction is more common and may reflect the inability of the anatomic RV to function as a systemic pumping chamber over a normal lifespan. The systemic ventricular dysfunction makes the heart more prone to arrhythmias. The best predictors of mortality in patients with systemic RV dysfunction are NYHA class and systemic ventricular ejection fraction.14 Despite the absence of symptoms of CHF or poor systemic ventricular ejection fraction, our patient developed hemodynamically unstable VT. Our case, thus, may represent an unusual group of patients with CCTGA who present for the first time with fatal VT as a risk for SCD.
Our review of literature focusing on the coronary arterial anatomy in CCTGA has demonstrated that some patients had significant coronary abnormalities,16–18 but interestingly, this was less frequent than what has been observed in other common congenital cardiac lesions.19–22 It is important to know of the presence of a coronary anomaly (in origin, course and distribution) in order to determine the optimal surgical approach and outcome.14 Previous studies have suggested a consistently inverted coronary arterial pattern in a patient with CCTGA and, rarely, a single coronary ostium or artery.7 In our patient, we found a single coronary ostium giving rise to right and left coronary systems. To our knowledge, there is only one case in the literature involving a patient with a single coronary ostium.17 An anatomical systemic ventricle, which makes a venous ventricle in a patient with CCTGA, presents challenges that are unique during ICD lead placement. Unlike a true RV, which is full of trabeculi where the ICD lead can be positioned, the anatomical systemic ventricle is devoid of these structures, thus making it harder to obtain a stable lead position and possibly increasing the risk of lead displacement. This can be overcome by selecting an active-fixation ICD lead from the beginning, and actively fixing it to interventricular septum. Secondly, the anatomical and fluoroscopic landmarks of the ventricle are completely altered, as chambers are backwards due to transposition of the ventricles. This requires the operator to use oblique views more frequently and to constantly remain aware of the anatomy during the implantation procedure.
The natural history in a patient with CCTGA is variable and not always well defined. Both bradyarrhythmia and tachyarrhythmia could be a potential cause for SCD in these patients. We recommend that a comprehensive EP evaluation should be done in all patients with CCTGA who present with syncope. If the EP evaluation is negative and other causes of syncope are excluded, a prophylactic ICD implantation with pacing capabilities should still be a consideration.
Acknowledgement. The authors are grateful to Dr. Deepak Kapoor and Dr. John Thornton for their critical help in preparing this case report.
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