Introduction: We present the case of an elderly female presenting with symptomatic, exercise induced desaturation who was subsequently found to have a massive left circumflex to coronary sinus congenital arteriovenous fistula (CAVF). A left to right coronary artery to coronary sinus shunt can result in a gradual rise in right atrial pressure sufficient to induce an intermittent right to left shunt across a patent foramen ovale with strenuous exertion and manifest as exercise desaturation. We discuss the prevalence, clinical presentation, pathophysiology of CAVF and propose a management scheme.
Case Presentation: 70-year-old female presented with a 2-year history of progressively increasing exertional dyspnea 10 minutes after the initiation of strenuous activity. She acknowledged sufficient exercise tolerance to complete activities of daily living and denied paroxysmal nocturnal dyspnea, orthopnea and a history of reactive airways disease. Physical examination revealed normal vital signs and an unremarkable examination of the thorax. Cardiovascular examination demonstrated an elevated jugular venous pressure at 4 cm with a prominent "v" wave, a third heart sound and a grade 2/6 systolic-diastolic murmur with a displace apical beat into the 6th interspace at the anterior axillary line. Peripheral examination did not demonstrate clubbing or cyanosis. A CXR (Figure 3) revealed enlargement of the cardiac silhouette with aberrant enlargement of the left heart border and demonstrated a dramatic interval change form a comparison film dated 7 years earlier. PFTs revealed an FEV1 of 1.92 L (81% predicted), FVC of 2.8 L (86% of predicted) with a KCO of 4.56 l/min/mm Hg (78% of predicted). Cardiopulmonary exercise testing demonstrated desaturation with exercise at 12 minutes (97% to 89%) with prompt return to normal after cessation of activity. A TTE revealed a normally contracting ventricle with a large echo free space in the region of the left atrium. TEE clarified the presence of a left circumflex artery to coronary sinus malformation, mild left ventricular dilatation, a persistently bowed interatrial septum form left to right and a stretched patent foramen ovale. A mibi scan confirmed the absence of stress induced ischemia. A left to right aorto-atrial shunt is not compatible with exercise desaturation. Subsequently, a dobutamine stress echo was performed to clarify the direction of flow across the foramen ovale: at rest, flow was persistently from the left atrium to the right atrium and no bubbles appeared in the left atrium. However, at peak dobutamine stress occasional bubbles appeared in the left atrium verifying the presence of a concurrent right to left shunt which we postulate occurred as right atrial pressure rose secondary to left to right shunting across the coronary arteriovenous malformation with strenuous exertion. An MRI (Figures 4 & 5) confirmed the origin to be the left circumflex artery and the insertion to be the corollary sinus. Cardiac catheterization confirmed the presence of a large, serpiginous fistula with massive venous ectasia and corresponding dilatation of the right sided cardiac chambers. A "step up" in oxygen saturation was noted from the right atrium (77%) to the right ventricle (83.3%). A patent foramen ovale, a 2:1 pulmonary to systemic flow ratio and normal pulmonary artery pressures (35/12/mean 20) were noted. Operative repair would have necessitated transsection of the pulmonary artery and aortic cross clamping to facilitate surgical access. In the absence of coronary artery disease, pulmonary hypertension or symptoms of cardiac decompensation a decision was made with the patient not to pursue surgical correction.
Discussion: A CAVF is a precapillary communication through which coronary arterial blood is shunted into a cardiac chamber, or great vessel thereby bypassing the myocardial capillary network occurring with a prevalence of 0.2% in autopsy and cardiac catheterization series. CAVFs may be classified as congenital or acquired. Low pressure structures are the most common recipient sites including the right ventricle (40%), right atrium (25%), pulmonary artery (15%), coronary slims (7%) and superior vena cava (1%). A continuous cardiac murmur resembling the murmur of PDA may be appreciated in an atypical location. Compared to a retrospective review population, a recent case series noted an increasing trend favoring symptomatic presentations with a predominance of chest complaints (34% vs 10%), a trend toward left sided CAVF and a congenital etiology. The most frequent manifestations included symptoms of dyspnea (25%), heart failure (20%), angina (20%) and myocardial infarction (4%). The lifelong risk of complications of CAVF including the risk of endocarditis, embolization, rupture and progression from an asymptomatic state to a more symptomatic presentation (dysrhythmias, heart failure, pulmonary hypertension mid ischemia) is not known. In the presence of atherosclerosis, symptoms, or significant left to right shunt ([is greater than] 2:1) elective closure of the CAVF is recommended. Treatment approaches in asymptomatic individuals are more controversial. Treatment options in an asymptomatic individual, with a small CAVF and no coexisting coronary artery disease include hypertension management and endocarditis prophylaxis. Alternative management strategies may include transcatheter embolization or expectant management. Options in the management of asymptomatic, large CAVF without CAD include expectant management with serial follow-up, transcatheter embolization or surgical ligation. Consideration should be given to the potential risks of early intervention, and to the possible benefits and risks of each intervention over expectant management.
Conclusion: Our ease highlights the importance of considering congenital abnormalities in the differential diagnosis of an adult presenting with a common respiratory complaint: dyspnea. A left to right coronary artery to coronary sinus shunt can result in a gradual rise in right atrial pressure sufficient to induce an intermittent right to left shunt across a patent foramen ovale with strenuous exertion and manifest as exercise desaturation. In the presence of CAD, symptoms of heart failure, ischemia, or dysrhythmias, or a significant left to right shunt elective closure is recommended. Management strategies in asymptomatic individuals without concomitant CAD warrant consideration of the potential risks of early intervention, and the possible benefits and risks associated with each intervention over expectant management. Each ease should be considered on an individual basis and in consultation with a cardiac surgeon.
Karen E. A. Burns, MD, FRCPC, J. Brown, MD, FRCPC, K. A. Ferguson, MD, FRCPC--London Health Sciences Center--University Campus, London, Ontario CANADA
COPYRIGHT 1999 American College of Chest Physicians
COPYRIGHT 2000 Gale Group
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