Local Pulmonary Malformation Caused by Bilateral Coronary Artery and Bronchial Artery Fistulae to the Left Pulmonary Artery in a Patient with Coronary Artery Disease

Abstract

At 10 years of age and again at 25, our patient had been treated for pulmonary tuberculosis due to the presence of a localized pulmonary shadow. Coronary angiography at age 59 revealed 3 fistulous communications: from the right and circumflex coronary arteries and from the left bronchial artery. All 3 emptied into the same recipient artery, the distal part of a left pulmonary artery branch, which produced substantial left-to-right shunt. On computed tomography, cystic formations could be seen in the pulmonic area.

The pulmonary tuberculosis for which this patient had been treated in his youth was in the same part of the lung where the shunt was discovered. Our conclusion is that the initial diagnosis was in error.

Among the congenital malformations of coronary arteries, fistulae are the 2nd most common anomaly, after abnormal origin. Fistulae can connect any coronary artery with another developing vascular structure, such as 1 of the cardiac chambers, the coronary sinus, or a pulmonary artery, vena cava, or pulmonary vein. ^1,2 The overall prevalence of coronary fistulae among adults referred for cardiac catheterization to investigate a primary complaint of angina is 0.11%. ³ As of 1993, only 400 cases had been reported. ⁴

The increased frequency of such reports in the past 40 years is probably the consequence of exact angiographic visualization enabled by the advent of cardiac catheterization. ⁵ Such cases are observed relatively often today. ³ The cause of the anomaly and the exact course of its embryogenesis are not always the same and are not yet clear. ^1,3 Half of all patients are asymptomatic until adulthood (about 20 years of age).

Congenital fistulae of the coronary arteries were 1st described in 1865, ⁶ and surgical intervention was not reported until 1947. ⁷ The management of patients with congenital coronary–to–pulmonary artery fistulae remains controversial, particularly from the viewpoint of operative intervention. ⁵

Case Report

A 59-year-old man was admitted in May 1998 for evaluation of dyspnea and apparent left heart decompensation. His history revealed a familial predisposition for ischemic heart disease. In 1993, an ergometer exercise test had precipitated a hypertensive reaction and angina at 7.1 MET, with depression of the ST segment in the electrocardiogram. The patient, who was a smoker, was on oral therapy for arterial hypertension and for diabetes. He was hyperglycemic. At 10 years of age, the patient had been treated for tuberculosis after a shadow was found in the basal segment of the left lung. At 25 years of age (in 1964), he underwent additional tuberculostatic therapy after a bronchoscopy revealed a small inflammatory process in the left basal part of the left lung.

Physical examination showed left heart enlargement with a low systolic murmur. The heart rhythm was regular (100 beats/min), with Q waves and horizontal depression of the ST segment in standard and unipolar electrocardiographic leads. Chest radiography showed cardiac enlargement (cardiothoracic ratio, 0.56) with increased pulmonary vasculature. On the left basal part of the lung, a shadow was seen.

The hemodynamic results were as follows. The pulmonary artery pressure was 36/22 mmHg (mean, 28 mmHg), and the mean pulmonary capillary wedge pressure was 18 mmHg. Oxymetry revealed substantial left-to-right shunt (Qp/Qs = 1.7), with the following oxygen saturation levels: superior vena cava 87%, 86%; inferior vena cava 88%; right atrium 86%, 87%, 88%; right ventricle 88%; pulmonary trunk 89%; right pulmonary artery 88%; left pulmonary artery 92%; and the left ventricle, aorta, and pulmonary vein 98%. The oxygen consumption rate was 250 mL/min. Systemic flow was at the rate of 2.43 L/min, and pulmonary flow was at the rate of 4.1 L/min. Echocardiography revealed a dilated left ventricular cavity and a diffuse hypokinetic reaction, especially in the basal portion. The ejection fraction was 30%. There was no important mitral regurgitation.

A computed tomographic (CT) scan of the chest showed cystic formations in the inferior lobe of the left lung; these appeared as fibrous, curving formations, with the approximate area of coverage being 4 × 4 × 6 cm (Fig. 1).

Fig. 1 Computed tomogram of the chest at the level between the pulmonary artery and the left atrium. The cystic formation in the left basal part of the left lung is seen (arrow).

Ao = aorta; LV = left ventricle; PA = pulmonary artery

We suspected left heart decompensation caused by a new myocardial infarction of the unknown region or by reinfarction of the inferior wall. A systolic murmur was considered a consequence of mitral incompetence in association with the pulmonary shadow seen on the chest radiograph. After successful recompensation, the patient underwent selective coronary angiography.

Ventriculography showed enlargement of the left ventricular cavity, with diffuse hypokinesia and an ejection fraction of 28%. No significant mitral incompetence was seen on angiography. Significant coronary lesions were found on the left anterior descending artery (LAD) and on the 1st and 2nd diagonal branches (D1, D2). The big marginal branch of the circumflex artery (LCX) was occluded, and retrograde filling was seen. Irregular stenosis of the proximal right coronary artery (RCA) and diminished filling of the distal RCA were seen (Fig. 2A).

Fig. 2 Right coronary artery (RCA) arteriogram in right oblique projection. An aberrant tortuous artery arises from the proximal segment of the RCA (A) and drains to the network and cavity positioned in the left basal part of the left lung (B). The fistula, which arises just before the proximal stenosis of the RCA (arrow), is of the same caliber as the coronary artery and passes near the left atrium, to the distal branch of the pulmonary artery.

F = fistula; K = catheter; NET = network; RCA = right coronary artery

The ostium of the 1st aberrant artery arose from the RCA just in front of the stenosis, and the 2nd aberrant artery arose from the LCX (Fig. 3). Both aberrant vessels had a large diameter and a long course near the left atrium, and they emptied into the same left distal branch of the pulmonary artery, where the vascular network was seen and the lung cavity was located—in the left posterior part of the lung (Fig. 2B).

Fig. 3 The left coronary artery in right anterior projection. A large vessel (arrow) originates from the distal circumflex coronary artery (LCX) and drains into the pulmonary artery (PA).

We positioned an additional catheter in the distal left pulmonary artery (Fig. 4), to reveal the precise location of the left-to-right shunt. Clearly visualized were the network that surrounded the cystic formation in the lung and the fistula as it emptied contrast medium into the pulmonary artery (Fig. 5).

Fig. 4 Selective pulmonary angiography of the right coronary artery in the left anterior oblique projection. The distal part of the fistulous connection (F) with the pulmonary artery is seen (arrow).

F = fistula; LA = left atrium; PA = left branch of the pulmonary artery

Fig. 5 Angiogram of the right coronary artery in the lateral projection. The distal part of the fistulous connection (F) with the pulmonary artery is seen. The network (NET) surrounds the cystic formation in the lung and contrast medium is seen emptying into the pulmonary artery branch (arrow). Observe the left-to-right shunt.

Bronchial arteriography revealed the connection between the left bronchial artery and the cystic formations of the lung. This anomalous artery also emptied into the vascular network (Fig. 6).

Fig. 6 Angiogram of the bronchial artery (BA) in the right anterior projection. The tortuous vessel drains into the lung network.

Surgery was performed 1 month later, through a median sternotomy. The left ventricle was seen to be enlarged, with poor contractions. Extracorporeal circulation was established, and myocardial protection was provided by antegrade and retrograde cardioplegia. Preparation of the left internal mammary artery showed good quality and diameter. We placed a left internal mammary artery graft on the LAD and saphenous vein grafts on the right coronary artery, the circumflex marginal branch, and both diagonal branches. We ligated the fistulae from the left and right arteries, but we left open the communication from the bronchial to the pulmonary artery.

The patient's postoperative course was uncomplicated, and he reported symptomatic relief.

Discussion

Yamanaka and Hobbs ⁸ reported that coronary anomalies appeared in 1.3% of 126,595 patients whose coronary arteriograms were reviewed. Both multiple and large fistulae were detected.

In their review of the literature on coronary artery anomalies, Nawa and colleagues ⁹ found that about 5% of such cases involved 2 or more anomalous arteries. Fistulae can be classified, in accordance with drainage site, into 2 major types: the PA type (draining into the pulmonary artery) and the CC type (draining into a cardiac chamber). Simultaneous presentation of both types is extremely rare. The pathogenesis of the 2 types may be different. At present, cases of the PA type are more commonly observed, but in our patient we found a 3rd communication, which arose from the bronchial artery and drained into the same part of the left pulmonary artery, where the pulmonary shadow and CT deformations were located. In our patient, 2 sorts of cardiac symptoms were present: angina pectoris arising from coronary artery disease, and symptoms of heart decompensation due to vascular overload caused by a hemodynamically significant left-to-right shunt.

It is now possible to recognize the pulmonary shadow from childhood as the consequence of congenital vascular anomalies. However, the pathogenesis of the fistulae from 3 different parts of the arterial circulation is still a question for discussion. The age of patients with congenital coronary fistulae plays a major role in the development of symptoms. In young patients, most fistulae are asymptomatic: in our patient, an incidental finding of a pulmonary shadow was the only sign in childhood.

The natural course and prognosis of bilateral coronary artery fistula is little known. In a symptomatic patient with coronary arteriovenous fistula, angina pectoris and chronic cardiac volume overload can occur.

The goal of surgical treatment was to relieve both the angina and the decompensation. In preparation for surgery, the chief problem for discussion was the communication from the bronchial artery to the pulmonary artery, which posed a risk of arterial damage.

Surgical correction of coronary artery fistula was pioneered by Björk, and several techniques of fistula repair are now available. ¹⁰ The techniques include internal closure of the fistula with proximal and distal ligation, and coronary artery bypass grafting. ¹¹ Ligation of fistulae has been shown to be a safe and effective form of therapy. Cardiopulmonary bypass is reserved for patients with otherwise inaccessible lesions or with coexisting cardiac lesions that require surgical repair. ^10,12 The decision to treat our patient surgically was based on a review of the literature. ¹³ Coil embolization, discussed by Mavroudis as a possible therapy, ² was not possible in our patient, because of multiple fistulous communications. Surgical treatment was indicated on the basis of the size of the fistulae, the patient's complex anatomy, the shunt ratio, and the other structural problems, including coronary disease. ^10,12 In this patient, the size and complexity of the affected arteries led to our choice of the simplest surgical procedure, i.e., proximal closure of the draining vessels and bypass grafting of the diseased coronary arteries. ¹⁴ The bronchial artery fistula was not ligated, and we did not even perform postoperative coronary angiography. We believe that this simple technique was effective and carried minimal risk for the patient. The fistulous coronary vessel is usually dilated in the section proximal to the fistula, sometimes to the extent that it is aneurysmal. A left-to-right shunt arises because flow through the fistula is greater than flow in the vessels that feed the myocardium. ¹⁵ In our patient, resistance flow was greater due to the high stenosis of the RCA, which resulted in substantial left-to-right shunt. Angina pectoris is thought to arise also from coronary artery steal syndrome. ¹⁶ Indeed this was even more responsible for angina in our patient: proximal stenosis of the RCA, located just behind the insertion of the fistula, created and exacerbated the steal phenomenon in the RCA. ^3,17

Saad describes acquired coronary fistulae. ¹⁸ In our patient, the condition was congenital. We believe that changes in the pulmonary parenchyma, which presented as a pulmonary shadow, were the result of additional congenital malformation.

As a child, our patient had been given tuberculostatic therapy, in accordance with a presumptive diagnosis of tuberculosis. In 1964, his 1st bronchoscopy, performed at a clinic in Vienna, appeared to support the possibility of tuberculosis. All subsequent investigations also concluded that the cause of the shadow was likely tuberculosis.

However, the last bronchoscopy, performed in our clinical center, showed a congenital pathologic malformation in the left lower region of the bronchial tree and excluded the specific disease (tuberculosis).

The findings in the lung and this patient's history of lung disease before the age of 20 influenced our conclusion that congenital causes were the probable reason for the development of the anastomoses and the fistulous communications—especially the one from the bronchial artery. Our suggestion is that the diagnosis of pulmonary tuberculosis proposed longer than 20 years ago is not correct.

Conclusion

This case is unique in the following aspects:

• There were multiple and bilateral coronary–to–pulmonary artery fistulae.

• A 3rd fistula arose from the bronchial artery and emptied partly into the pulmonary artery.

• All 3 fistulae emptied into the same portion of the lung, where a specific disease process had been diagnosed.

• Multiple fistulae were present in a patient who had atherosclerotic coronary artery disease.

• The only clinical symptom of fistulae was misdiagnosed in childhood as a lung disorder.