It is thought that most coronary artery fistulae are congenital in origin, resulting from the persistence of intratrabecular sinusoids during embryonic development.1,2 The persistence of these sinusoids results in the communication between the coronary artery and a cardiac chamber, a cardiac vein or another artery. Although it is thought that most of these fistulae are embryologic remnants, non-congenital fistulae have been reported. Iatrogenic fistulae have been reported post-operatively after such procedures as mitral valve replacement3 and endocardial biopsy after heart transplantation.4 These fistulae have also been reported to develop as a consequence of chest trauma.5 The presence of fistulae is a rare occurrence in itself, but the different origins and drainage sites of these fistulae make them even more rare. Coronary artery fistulae account for about 0.31% of all congenital heart defects.6 Coronary artery fistulae are noted in about 2% of coronary angiograms.7 These fistulae usually affect the right coronary artery and drain into one of the cardiac chambers, most commonly the right ventricle or right atrium.8,9 We report the case of a 74-year-old woman with a history of congestive heart failure who was found to have a rare left coronary fistula draining into a persistent left superior vena cava (LSVC) into a markedly dilated and aneurysmal coronary sinus. Case Report. A 74-year-old woman with a history of hypertension and hypercholesterolemia developed unexplained heart failure. Her cardiac history started when she underwent placement of a pacemaker for the development of atrial fibrillation accompanied by episodes of bradycardia and intermittent bundle branch block and symptoms of syncope (tachycardia-bradycardia syndrome). After an electrophysiology study showed extensive His-Purkinje conduction disease, pacemaker placement was attempted using the standard left subclavian approach. However, it was noted that the guidewire went toward the left side of the heart. Contrast venography disclosed that the patient had a persistent left superior vena cava. The next day, the pacemaker was placed from the right subclavian approach without complications. Over the months following pacemaker placement, the patient started having worsening symptoms of shortness of breath especially on exertion, edema and nocturia. Examination revealed signs of congestive heart failure, including bilateral lower extremity edema and crackles on lung examination. The patient was also noted to have a short II/VI systolic murmur at the base as well as a III/VI holosystolic murmur heard best at the apex. Echocardiography demonstrated mild aortic stenosis, mild tricuspid regurgitation and moderate mitral regurgitation with moderate pulmonary hypertension (estimated pulmonary artery systolic pressure, 50 mmHg). The ejection fraction was estimated at about 70%. The patient was diuresed and her shortness of breath improved. Even though treatment with diuretics helped the patient, she continued to go in and out of heart failure over the following year. The patient’s physical exam continued to display signs of heart failure with worsening peripheral edema, and specifically her cardiac exam now showed a more noticeable murmur which appeared to be continuous throughout the cardiac cycle. At this time, it was felt that the patient might benefit from reversion to sinus rhythm to help prevent these frequent episodes of heart failure. She was scheduled for and underwent cardiac catheterization prior to attempts at cardioversion. Cardiac catheterization showed a large left main coronary aneurysm and fistula draining to a persistent left superior vena cava into a dilated coronary sinus. An echocardiogram was then performed; it showed an ejection fraction of about 80% with moderate to severe tricuspid regurgitation, moderate pulmonary hypertension with right ventricular dilation and a severely dilated coronary sinus with turbulent color Doppler flow. The Qp/Qs ratio was calculated at 2:1, suggestive of a significant left to right shunt. The patient returned for repeat cardiac catheterization to further delineate the fistula and evaluate the shunt. In the repeat catheterization, a 2:1 shunt was noted and although efforts were made to locate a “choke-point” for coil embolization, none was found. Interventional transvenous stent-graft occlusion of the entry point to the vena cava was determined to be unfeasible. The patient was then referred for surgery. The patient was taken to surgery for closure of the coronary arteriovenous fistula by primary suture closure utilizing hypothermic circulatory arrest. At the operation, a left main coronary artery aneurysm was found to be at least 6 x 3 cm in dimension. The oval-shaped aneurysm was thin-walled, with evidence of calcification in its walls. The communication between the arterial aneurysm and the venous system was noted after posterolateral venotomy in the left-sided superior vena cava and extension down to the posterior aspect of the coronary sinus. The communication was that of a discrete hole, which appeared to be an erosion of the aneurysm into the coronary sinus. The margins of the communication were irregular, with a diameter of about 5–10 mm. Primary closure of the communication was undertaken. The left main coronary artery aneurysm was not treated by exclusion with ligation due to the presence of arterial branches supplying myocardium from the aneurysm. Discussion. Coronary artery fistulae account for about 0.31% of all congenital heart defects. The overall population incidence is estimated at 0.002%. Coronary artery fistulae are noted in about 2% of coronary angiograms.6,7 In our patient, the fistula was discovered on angiogram. The patient had been experiencing progressive congestive failure and this was felt to be secondary to the increase in left to right shunting as the fistula size and flow increased. After entertaining all of the congenital and non-congenital causes of these fistulae in our patient, it was felt that this patient, who had a long history of hypertension, likely had the development of this fistula over a period of time where erosion and fistulization took place from the left main artery aneurysm into the persistent left superior vena cava and coronary sinus due to increasing pressures. The different origins and drainage sites of these fistulae differentiate the rarity and uniqueness of the various types. Since the first description of coronary artery fistulae by Krause in 1865,2,10 several reports of this entity and its common locations have been published in the literature. The fistula affects the right coronary artery in 50% of cases, the left coronary artery in about 42% of cases and both the left and right in 5% of cases.8 The points of drainage include the right ventricle (41%), the right atrium (26%), the pulmonary artery (17%), the coronary sinus (7%), the left atrium (5%), the left ventricle (3%) and very rarely the superior vena cava (1%).8,9 In comparison with these figures, our case is unique in the sense that the fistula originated from the left main coronary artery and drained through the persistent LSVC into the coronary sinus. Both the origination point and termination point of this fistula make it highly rare and the combination of the rare origination and termination points with the presence of the persistent LSVC make it even more unusual. In our patient, the persistent LSVC was noted incidentally while pacemaker leads were implanted. Persistent LSVC is a congenital entity that develops as a remnant of aberrant embryological development in certain fetuses. The remnant LSVC commonly drains into the coronary sinus. Depending on the severity of the malformation, it may also drain into other structures such as atrial chambers or other coronary veins. Nsah et al. noted that a persistent superior vena cava draining into the coronary sinus was found in 104/1208 hearts (9%) with a congenital anomaly. Associations between a persistent LSVC and atrioventricular canal defects, cor triatrium and mitral atresia were commonly noted. Less frequent associations were found between retained LSVC and atrial septal defects and patent foramen ovale.11 The final diagnosis and treatment of our patient was made possible through accurate and appropriate imaging techniques. The ideal imaging tools for the diagnosis and delineation of coronary fistulae include echocardiography and angiography. Studies have shown that echocardiography, specifically echo Doppler, is a helpful diagnostic tool for the identification of coronary artery fistulae. Usually, the larger and more proximal the fistula, the easier it is to note the turbulent flow pattern highlighted by pulsed Doppler on two-dimensional echocardiography.2,12,13 In our reported case, the initial echocardiogram did not show any evidence of the fistula and the second echocardiogram one year later showed the presence of the coronary sinus into which the dilated aneurysmal fistula drained with turbulent flow on Doppler. The use of cardiac angiography has become common to better delineate the location of a coronary fistula that may have been suspected on echocardiography. Not only is cardiac catheterization a diagnostic modality, but it can also serve as a treatment modality to deliver coil embolization at a point to close off the communication. Armsby et al. recently showed that the transcatheter closure of coronary artery fistulae is an acceptable and efficacious alternative to surgery in most patients.14 Even though transcatheter closure of these fistulae is probably the ideal method for treatment as they dilate and begin to affect cardiac function with time, it is not always possible, as was seen in this case, to find a point ideal for embolization. It is also not always feasible to undertake interventional transvenous stent-graft occlusion of the entry points into the vena cava. In these patients, it is necessary to proceed to surgery.15–17 Conclusion. We reported the case of a 74-year-old woman with a history of congestive heart failure who was found to have a rare left main coronary fistula draining into a persistent LSVC into a markedly dilated and aneurysmal coronary sinus. The interest in this case was sparked by the unique nature of the combination of a left main coronary fistula with a retained LSVC. The patient in this case likely did not have this fistula at birth. It appeared (and was confirmed during surgery) that the communication in this patient was due to erosion, secondary to increased pressure in the expanded coronary aneurysm, into the coronary sinus. The patient become more and more symptomatic as the aneurysm and fistula dilated and allowed for increased left to right shunting, as is the natural progression. After surgical repair of the fistula, the patient’s clinical state improved. After a brief rehabilitation period, she returned home and is doing well.
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