Infective Endocarditis of the Left Main to Right Atrial Coronary Cameral Fistula.

A 7-year-old female child presented with pyrexia of unknown origin. She had received an empirical regimen of antibiotic for possible endocarditis. Evaluation included multiple imaging supports and blood culture. She had left main coronary artery to right atrium coronary cameral fistula, restricted patent ductus arteriosus, vegetation at the right atrial exit of fistula and negative blood culture. Ongoing fever more than 2 weeks, oscillating vegetation in the echo and histopathological evidence of healing vegetation suggested definite diagnosis of infective endocarditis. She was treated successfully by surgical closure of fistula from the right atrial approach. Device closure in this case would have resulted in a large residual cul-de-sac with or without tiny residual high-velocity jets, either being a threat for future enlargement, rupture of the residual aneurysmal sac, thromboembolism, prolonged anticoagulation, and infective endocarditis.

INTRODUCTION

A giant (≥3 times of diameter of the coronary artery) coronary cameral fistula (CCF) of the left main coronary artery (LMCA) associated with patent ductus arteriosus (PDA) is rare.[12] The origin, course of the fistulous tract, size, neighboring structures, exit, shunt size, symptoms and associated with complications such as rapid growth, thromboembolism, infective endocarditis, and coronary steal are the variables those decide closure technique and follow up course. Large oscillating vegetation at the origin or exit of CCF is extremely rare. Surgery is preferred to device closure because of very good, long-term, event-free survival.[34]

CASE REPORT

A 7-year-old female child presented to us with low-grade fever, chill, and loss of weight for last one month. She was treated outside as a case of pyrexia of unknown origin as was mentioned in the referral note with some antibiotics. History in detail revealed three to four episode of lower respiratory tract infection without expectoration per year. These lower respiratory tract infections were treated successfully without hospital admission. Clinical examination revealed asthenic body built. Palpation and auscultation confirmed a systolic thrill with underlying a superficial cat purring continuous murmur in the right parasternal border. Chest radiograph showed pulmonary plethora. Twelve-lead electrocardiograms were within normal limit. Two-dimensional and color Doppler echocardiography revealed a restricted PDA of the narrowest diameter of 2 mm at the pulmonary arterial end. The dilated LMCA measured 6–7 mm at aortic end with a large (2.5 cm × 1 cm) oscillating vegetation at the exit into the right atrium (RA) [Figure 1 and Video 1]. The modified apical five-chamber view and parasternal short axis view showed a tortuous tract with the high-velocity turbulent flow. The tract was opening into RA above the tricuspid valve. Although we could not trace the fistulous tract completely, we made a provisional diagnosis of CCF connecting LMCA to RA. There was mild dilatation of RA, right ventricle and pulmonary artery, mild pulmonary arterial hypertension (PAH), and good biventricular function. Blood cultures were negative for any microbial growth. All the three repeated blood cultures in succession were negative for any microbial growth. The definite diagnosis of infective endocarditis was made by clinical criteria under modified Duke's criteria.[5] The criteria that qualify for definitive infective endocarditis in this case included one major (large freely oscillating vegetation in echocardiography) and three minor criteria (fever ≥5 days, existing structural heart disease, and rheumatoid factor positive in very low titer). Cardiac catheterization showed left to right (L to R) shunt size of 1.7:1, mild PAH. Aortic root angiogram in anterior–posterior view confirmed CCF of LMCA to RA. The fistulous tract was narrowest at the right atrial end with waist size 3 mm following an ampulla just before entry into RA. Aortic root angiogram also showed left anterior descending (LAD), ramus intermedius, and left circumflex (LCX) coronary arteries were arising from dilated LMCA [Figure 2]. The right coronary artery was normal. Both echocardiogram and coronary angiogram could not clarify the exact three-dimensional course of this tortuous fistula. Cardiac magnetic resonance angiogram with contrast enhancement (CMRI-1.5 Tesla) showed a tortuous, giant aneurysmal dilated fistulous tract running posterior-superiorly and parallel to coronary sinus. The tract had an intramyocardial course in most of its course. The length of CCF was 4 cm, and the ostial opening was 7 mm in diameter. The average diameter of CCF was 5 mm. The right atrial opening was located just superior to coronary sinus ostium. The coronary arteries from L to R from LMCA in order were LCX coronary artery, ramus intermedius, and anterior descending coronary artery [Figure 3]. Because of a large recently treated large vegetation and significantly large aneurysmal fistulous tract, we preferred surgical closure. Median sternotomy and standard bypass techniques were used. We could feel thrill over RA and pulmonary artery. Small PDA was ligated. Incision on the right atrial free wall showed fistulous tract opening of size 3–4 mm just above and posterior to the coronary sinus. The fistulous tract was closed at venous end from the right atrial approach. Then, the ampulla part of fistula was marsupialized after closing the arterial end close to it, aiming maximum reduction of fistulous tract length. Aortotomy was performed to rule out vegetation in the entry point. The vegetation at the exit was quite small because of healing [Figure 4] which was excised completely. The aneurysmal dilation LMCA, tortuous tract, and the origin of all the three coronary arteries (LAD/LCX/ramus intermedius) from left main were the major hindrances in closing this fistula from the aortic wall itself. She was discharged without any postoperative complication on the 10th postoperative day. There was now bacterial or fungal growth in tissue culture (vegetation specimen). The histopathology report showed healed vegetation with predominant collagen tissue and paucity of cellular elements. She has completed a follow-up 3 years. Echocardiography showed no residual shunt or increase in the residual blind sac. She was kept on warfarin aiming INR 2-3 to prevent thromboembolism from blind sac for first 3 months followed by ecosprin.

Figure 1

Two-dimensional echocardiography in apical modified five chamber view with anterior swipe shows vegetation marked by white arrow at the exit of the fistula in the right atrium just above the ostium of the coronary sinus

Figure 2

Coronary angiogram of the left main in the anterior–posterior projection showed the fistula. The details of pathology were not obvious

Figure 3

Cardiac magnetic resonance angiogram shows aneurysmal dilatation of fistulous tract running parallel to coronary sinus posterior-superiorly. The coronary arteries from left to right from the left main coronary artery in order were left circumflex, ramus intermedius, and left anterior descending coronary artery

Figure 4

Right atrial approach to excise the vegetation and close the coronary cameral fistula was consistent with significantly healed vegetation (very small size)

DISCUSSION

The left coronary artery fistula accounts for 7% of CCF.[1] Three cases left main CCF have been reported by Mavroudis et al. including only one case of LMCA CCF was associated with PDA.[67] There are also some individual case reports of left main CCF.[89] In the review article by Said showed LMCA fistula that drains into pulmonary artery (46%), coronary sinus or RA (29%), right ventricle (6%), superior vena cava (12%), and none into the left ventricle.[1] Of these cases, 18% had an aneurysm, 47% underwent surgical ligation, 41% medical management, and 12% had undergone catheter-based intervention. Only 4% of 304 patients had infective endocarditis involving valves and at the venous exists but none of them had origin vegetation. The mere presence of vegetation is not an absolute contraindication for percutaneous closure of fistulous tract, if the vegetation is small, reduces to insignificant size on treatment.[1011] The timing of surgery in such situation should be as early as possible without waiting for the healing of the vegetation.[12] Therefore, we have done surgery without delay. The choice of technique to close the fistula depends on origin, exit, tortuosity, size, length, flow status, aneurysmal dilation, and the point of intended occlusion site and intra- or extra-cardiac course of fistula. Management decision is also influenced by the presence or absence of several variables such as associated congenital malformation, complication (infective endocarditic, thromboembolism,[6] thrombosis[11] rupture, and coronary steal), and the size of the fistulous tract. After operation, if the residual blind sac grows faster in size, the patient may need a redo operation. A large residual sac, especially after device closure, may need lifelong oral anticoagulation or surgery. Therefore, a watchful follow-up is mandatory in either condition to watch for future enlargement of the residual sac.[4] However, the event-free survival is always better with surgery. The active inflammation in the vegetation in this case could have been detected using PET scan prior to starting the antibiotic course.[13]

CONCLUSION

This rare case of LMCA to RA CCF with PDA illustrated a large oscillating vegetation at the right atrial exit in case of partially treated infective endocarditis. It was evaluated by multiple imaging methods, blood culture, and biopsy. Surgical repair was preferred to device closure because giant aneurysm involving left main. A 3 years follow by echo was uneventful.

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Conflicts of interest

There are no conflicts of interest.