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Ann Thorac Surg 2003;75:282-284
© 2003 The Society of Thoracic Surgeons
a Heart Institute, Albany Medical College, Albany, New York, USA
Accepted for publication July 31, 2002.
* Address reprint requests to Dr Canver, Heart Institute, Albany Medical College, 47 New Scotland Ave, Mail Code 55, Albany, NY 12208-3479, USA
e-mail: canverc{at}mail.amc.edu
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| Introduction |
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A 46-year-old female with congestive heart failure was referred for an operation after coronary angiography documented anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA). She had no angina, but she had a New York Heart Association functional class IV heart failure with profound orthopnea.
The patient was in moderate respiratory distress with bibasilar rales and had controlled atrial fibrillation. Jugular venous pulsations were visible at the angle of her jaw. Cardiac auscultation revealed S1 of normal intensity, accentuated P2, a distinct S3 and a grade 4/6 murmur of mitral regurgitation (MR). She had moderate ascites, bipedal edema, and mild icterus.
Twelve-lead electrocardiogram showed atrial fibrillation. Chest roentgenogram demonstrated pulmonary edema and moderate sized pleural effusions. Echocardiography showed severe left ventricular dysfunction, severe MR, pulmonary hypertension, moderate tricuspid regurgitation, and ALCAPA. Left heart catheterization demonstrated a left ventricular ejection fraction of 25% with severely elevated left ventricular end diastolic pressure of 35 mm Hg and 4+ MR. Coronary angiography revealed an ectatic right coronary artery that supplied collaterals to the entire left coronary system. The left coronary artery originated from a nonfacing sinus of the pulmonary artery. Right heart catheterization revealed severe pulmonary hypertension (pulmonary artery pressure 80/50 with mean of 55 mm Hg) and severely elevated pulmonary capillary wedge pressure (40 mm Hg with v wave peak of 60 mm Hg). Cardiac index was 2.8L/m2/min. Mixed venous oxygen saturation was 52.2%. PVR was 3.2 Wood units. Shunt fraction (pulmonary to systemic) was 0.9. Nitroprusside infusion documented partial reversibility of pulmonary hypertension. An intraaortic balloon pump was placed and milrinone infusion was initiated.
Intravenous heparin prophylaxis for systemic embolism was started (this was a reexposure after heparin, which was received 7 days earlier). The platelet count of 350,000/µL dropped to 140,000/µL on day 4 and hit its nadir (51,000/µL) on day 6. Blood drawn for platelet factor 4 antibodies on day 4 of reexposure confirmed heparin-induced thrombocytopenia. An enzyme-linked immunoadsorbent assay based GTI-PF4® (GTI Inc, Brookfield, WI) diagnostic kit was used with 0.4 optical density unit or above being considered positive. Heparin-coated lines and flushes were withdrawn. Intravenous lepirudin was substituted, with prompt improvement in platelet count.
Overwhelming concerns about the reversibility of myocardial dysfunction (high left ventricular end diastolic pressure and low ejection fraction in the setting of severe MR) influenced a decision to list the patient status 1A for orthotopic heart transplantation (OHT). Thirteen days after documentation of heparin-induced thrombocytopenia, an allograft became available and she underwent OHT.
Lepirudin was stopped 6 hours before the operation. Conventional heparinization (3 mg/kg) and ascending aortic and bicaval venous cannulation were used to institute cardiopulmonary bypass (CPB). A standard four anastomosis (Shumway) technique was used for the OHT. CPB time was 145 minutes, and allograft ischemic time was 248 minutes. Platelet count remained more than 200,000 for the entire operation. The perioperative period was uncomplicated. Although the elimination half-life of lepirudin is approximately 1.3 hours, substantial chest tube drainage (1,260 mL in the first 24 hrs) was attributed to residual lepirudin that had been discontinued before the operation. Four units of fresh frozen plasma, one unit of pheresed platelets, and six units of packed red cells were transfused perioperatively. The intraaortic balloon pump was removed, and the patient was extubated on the postoperative day 1. A standard immunosuppression regimen with OKT3 induction, steroids, cyclosporin, and mycophenolate mofetil was used. Thirteen days after the operation the patient returned home. Surveillance endomyocardial biopsies have shown no significant rejection episodes in over 1 year of follow-up. The patient has returned to a normal lifestyle with no limitations to physical exertion.
The explanted heart (Fig 1) revealed severe endocardial and subendocardial fibrosis of the left ventricular myocardium and papillary muscles. The right ventricle was affected to a lesser extent. Myocardial sections showed scattered foci of interstitial fibrosis from prior infarctions and foci of calcification.
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| Comment |
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ALCAPA is characterized by a coronary steal that occurs from the right coronary artery through dilated collaterals to the left coronary artery and thence to the low pressure pulmonary circulation. This results in myocardial ischemia with associated myocardial infarction, papillary muscle dysfunction, and MR, and physiology of a left to right shunt.
"A 20-year-review of the surgical management of ALCAPA by Backer et al [2] outlines the historical aspects of surgery for this entity. Though first described by Brooks, the disorder is known after Bland, White, and Garland who in 1933 described an anginal type of syndrome in a three-month-old infant. The first successful operation by Sabiston involved ligation of the anomalous vessel at its origin. Cooley reported saphenous vein bypass grafting of the anomalous artery in 1966. Meyer reported left subclavian artery anastomosis to the anomalous left coronary artery in 1968. Internal mammary artery grafting has subsequently been performed. Recent surgical techniques include aortic implantation of the anomalous coronary artery, and creation of a coronary tunnel within the pulmonary trunk between a created aorto-pulmonary window and the left coronary ostium (Takeuchi operation) [2]. OHT for intractable left ventricular failure from ALCAPA in childhood was reported by Mavroudis in 1988 and Starnes in 1989. Biological bridging with heterotopic heart transplantation (to support a severely impaired left ventricle) and concomitant tunnel repair of ALCAPA has been described, with successful explantation of the allograft following native heart recovery and allograft ventricular arrest [3]."
Establishment of a two coronary arterial system for patients with ALCAPA restores a physiologically normal pro-grade flow to the left ventricle, and this is the operation of choice when myocardial recovery is anticipated. Although even severely depressed myocardial function recovers in pediatric patients, there are some patients who present with profound cardiogenic shock or end-stage cardiomyopathy who may need cardiac transplantation [2].
In adults, operations should address repair of the anomalous anatomy and potential repair of MR. Ligation of the anomalous artery with coronary artery bypass grafting (saphenous vein or internal mammary artery) carries a 1% mortality, but concomitant mitral valve operation adds to the risk. Persistent MR, left ventricular dysfunction, and potential for malignant dysrhythmias from subendocardial fibrosis are concerns with conventional anatomic repair in adults. Preoperative estimation of myocardial blood flow and metabolism by positron emission tomography (PET) may help predict the likelihood of postoperative reversal of ischemic injury [1].
CPB for OHT in a patient with heparin-induced platelet factor 4 antibodies, using enoxaparin has been reported [4]. A variety of other techniques for conducting CPB in patients with platelet factor 4 antibodies also have been described. Our experience with CPB in patients with heparin-induced thrombocytopenia undergoing coronary bypass operation is similar to some reports [5, 6] in that such patients can safely sustain the massive heparin re-challenge of CPB, provided that in vitro aggregation has ceased and re-challenge therapy is not prolonged.
ALCAPA in the adult may present a therapeutic dilemma. With preserved left ventricular function, anatomic repair to establish a two coronary system is indicated. When patients present with features of a cardiomyopathy, OHT is an option. However when presentation is with moderate left ventricular dysfunction and ventricular dysrhythmias, a judgment call is indicated based on resources and the experience of the surgical team.
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