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J Thorac Cardiovasc Surg 1994;107:1172-1174
© 1994 Mosby, Inc.
LETTERS TO THE EDITOR |
Fort Worth, TX 76104
To the Editor:
Anomalous origin of the left coronary artery from the pulmonary trunk is a rare lesion. In recent years, early diagnosis and surgical intervention have offered a more favorable outlook for this previously difficult lesion. Despite this, older children and adults still have some of the sequelae of coronary insufficiency, including mitral insufficiency, left ventricular dysfunction, aneurysm formation, and endocardial fibroelastosis.
Our patient was initially examined at 3 months of age for symptoms of irritability and emesis. A workup that included cardiac catheterization showed anomalous origin of the left coronary artery and a poorly contracting left ventricle. Ligation of the left coronary artery was considered at that time. With clinical improvement and intervening social issues, however, no operation was performed and the child's condition was medically managed with digoxin and diuretics.
During the next several years, rapid atrial fibrillation and increasing symptoms of congestive heart failure led to the addition of procainamide and captopril to the medical regimen. The child, although always quite thin and frail, was able to lead a fairly active life. One year before admission, the child began to have dyspnea, orthopnea, and marked weight loss. Two days before his arrival at our institution, the patient was admitted to an outlying hospital with emesis, cough, and increased respiratory distress. He was transferred for possible surgical intervention.
Initial examination revealed a cachectic, tired-appearing, 8-year-old boy in mild respiratory distress. His weight was 15 kg, his blood pressure was 90/60 mm Hg, cardiac rhythm was irregular at 140 beats/min, and respiratory rate was 32 breaths/ min with 2/6 work of breathing. The pericardium was extremely active with a visible left ventricular lift, a single second heart sound, an S4 gallop, and a grade 2/6 holosystolic murmer. Chest examination revealed decreased breath sounds in the left lower lobe, with rales halfway up the thorax. The liver edge was palpated 6 cm below the right costal margin. Extremities had 2 +pulses throughout and were slightly cool. The chest x-ray film demonstrated massive cardiomegaly with a cardiothoracic ratio of 0.75 (predominantly caused by left atrial enlargement), centrally prominent pulmonary arteries, and compression atelectasis of the left lower lobe (Fig. 1). An electrocardiogram demonstrated atrial fibrillation, with an irregular ventricular response and deep Q waves in all lateral leads. Laboratory tests reflected the impact of the child's cardiac cachexia on other organ systems.
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Initial therapy included elective intubation, hyperalimentation, amrinone, and dopamine. Cardiac catheterization confirmed a left-to-right atrial shunt, as well as a left-to-right shunt from the right coronary artery through collaterals to the left coronary artery and then retrogradely into the pulmonary artery. The pulmonary/systemic flow ratio was calculated at 2.1:1. The right ventricular pressure measured 63/8 mm Hg and the pulmonary artery pressure measured 65/30 mm Hg, with an aortic pressure of 107/71 mm Hg. The left atrium was not entered, but the pulmonary artery wedge pressure was 24 mm Hg with a V wave of 29 mm Hg.
On the fourth hospital day, the child became febrile with a temperature of 40° C and an elevated white blood cell count developed. Staphylococcus aureuswas isolated from the patient's sputum. Despite medical management with positive-pressure ventilation and antibiotics, the child's condition continued to deteriorate. Surgical repair of the anomalous left coronary artery and mitral valve and elective insertion of an intraaortic balloon were therefore performed.
With entrance into the mediastinum, significant distortion of the normal cardiac anatomy was noted from a grossly enlarged left atrium. The left atrium was enlarged, grade 6/6. The left ventricle was enlarged, grade 2/6. The right atrium was enlarged, grade 3/6. The right ventricle was enlarged, grade 3/6. The left atrium itself was almost spherical and was quite tense. The main pulmonary artery was somewhat enlarged.
On opening of the pulmonary artery, the anomalous left coronary artery was seen to arise from the left posterior aspect of the pulmonary artery. The pulmonary valve itself was tricuspid and normal. The right coronary artery, as seen externally, was somewhat enlarged and tortuous but ran in the normal distribution. Inside the left atrium, the mitral valve was noted to be severely regurgitant, with extreme prolapse of the anterior leaflet as a result of elongated chordae. There were two sets of chordae, one superior and one inferior, both of which were elongated 1.5 cm. The papillary muscles to which these chordae were connected were fibrotic. The posterior leaflet was prolapsing centrally in a region not attached to any chordal structures. The tricuspid valve also demonstrated moderate incompetence, with some regurgitation located centrally and some related to stretching of the anulus in the region of the anteroposterior commissure. The leaflets themselves were normal. The atrial septum was bowed toward the right atrium from the extremely elevated left atrial pressure. An atrial septal defect measuring approximately 2 cm was noted. This could have been derived solely from a significantly stretched patent foramen ovale.
Cardiopulmonary bypass was commenced with direct bicaval cannulation. The patient was cooled to 25° C. Because of the anomalous origin of the left coronary artery, cold sanguineous cardioplegic solution was infused initially in a retrograde fashion only, with the antegrade cardioplegia cannula in the aorta and an incision in the pulmonary artery for venting of the cardioplegic solution.
The pulmonary artery was opened transversely and the left coronary ostium was identified. An 8 mm aortopulmonary window was created between the pulmonary artery and the aorta. After this, an 8 mm Impra polytetrafluorethylene tube graft (Impra, Inc., Tempe, Ariz.) was cut to form the anterior wall of the tunnel, which was placed to direct the blood from the aorta to the left coronary artery orifice. The inferior wall of the tunnel was just at the posterior commissure of the pulmonary valve but did not appear to affect pulmonary valve competence. Once this was completed, further cardioplegic solution was administered in an antegrade fashion through the aorta. The main pulmonary artery was closed with a transverse pericardial patch.
Attention was then turned to the mitral valve. The anatomy was as described. The two sets of chordae to the anterior leaflet were shortened to an appropriate length by means of techniques described by Carpentier and coworkers. 
1 The midportion of the posterior leaflet was addressed by performing a quadrangular resection of approximately 8 mm of tissue. A No. 28 Carpentier annuloplasty ring was then placed. When this was cinched down, only a small degree of regurgitation was noted at the posteromedial commissure. The tricuspid valve was then examined and a De Vega annuloplasty, approximately 2 cm in length, was performed at the junction of the anterior and posterior leaflets. After this, the atrial septal defect was closed.
During rewarming, a 7 cc intraaortic balloon was placed into the right femoral artery through a 5 mm thin-walled Impra polytetrafluoroethylene graft, which was attached longitudinally to the femoral artery. With rewarming, cardiac action appeared to be acceptable. Moderate inotropic support and the intraaortic balloon pump were used to wean the patient from cardiopulmonary bypass. Hemodynamics with this were quite good, with a systolic blood pressure of 95 mm/Hg and a left atrial pressure of 14 mm Hg. No true regurgitant jet could be palpated in the left atrium.
Despite acceptable hemodynamics in the operating room, the patient's early postoperative course was quite difficult because of low cardiac output, relative hypoxia, and bleeding caused by profound coagulopathy. However, these issues were addressed successfully with continued pressors, the intraaortic balloon pump, and ventilatory support. Echocardiography 24 hours after the operation demonstrated acceptable ventricular function, mild mitral regurgitation, no tricuspid regurgitation, an open left coronary artery tunnel, and no regurgitation through the pulmonic valve. Left ventricular hypertrophy was resolving; the left atrial size had decreased to 54 mm. Cardiac output and ventricular function continued to improve; the patient was weaned from the intraaortic balloon pump, which was removed at 36 hours after operation.
With stable hemodynamics, the patient was weaned gradually from ventilatory support and extubated on postoperative day 4. However, increased work of breathing and respiratory acidosis led to reintubation on postoperative day 6. Examination with flexible fiberoptic bronchoscope demonstrated chronic marked compression of the left main-stem bronchus and a lesser degree of compression of the right main-stem bronchus. The child therefore received ventilatory support and hyperalimentation for an additional 10 days. At the end of this period, he was extubated successfully. At that time, attention was turned to enteral feedings and aggressive pulmonary toilet. The child's condition continued to improve, and he was discharged on postoperative day 28.
Six months later, follow-up showed an active child. The chest radiograph demonstrated total resolution of the left lower lobe atelectasis. The heart size was much smaller, with a cardiothoracic ratio of 0.55 (Fig. 2). Echocardiography demonstrated decrease of left ventricular inner dimension at end-diastole to 47 mm and of left ventricular internal dimension at end-systole to 29 mm. Most markedly, a decrease in left atrial size to 35 mm was noted, with only 1 to 2+ insufficiency of the mitral valve.
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2 are an important new addition to the pediatric surgeon's repertoire. Because of this child's marginal ventricular function, the destruction and distortion of ventricular structure associated with valve replacement most probably would have led to a fatal outcome. In addition, the requirement for coumadin with a mechanical valve would have been difficult because of the child's social situation.
Second, we believed it important to leave the child with a 2-coronary artery system. In view of the posterolateral location of the anomalous coronary artery on the pulmonary trunk and the relatively stiff tissues of an 8-year-old child, reimplantation was not an option. Takeuchi and associates 3 flap repair would also have posed some problem, again because of the decreased pliability of tissue in a child of this age.
A split tube graft was used to roof the tunnel from the aorta to the anomalous left coronary artery without any distortion of the pulmonary valve. The main pulmonary artery was closed with a pericardial patch to prevent narrowing. With this technique, there was no pulmonic insufficiency or stenosis and there was only minimal turbulance. Because of the degree of pulmonary artery hypertension, this was an important consideration in this case.
Third, this is to our knowledge the first reported case of the "elective" use of an intraaortic balloon pump in a child. Several reports describe the use of intraaortic balloon counterpulsation to treat children with extremely low cardiac output. 4 Although many adults with poor ventricular function have intraoperative insertion of an intraaortic balloon to facilitate a smooth postoperative course and minimize the necessity for high-dose catecholamines, this has not often been reported in the pediatric population. Despite the fact that this patient could have been weaned successfully from cardiopulmonary bypass and despite the fact that the actual systolic augmentation from the intraaortic balloon pump was minimal (i.e., 5 to 10 mm Hg), we are convinced that the effect of the intraaortic balloon pump on diastolic unloading enabled the patient, to survive the episode of low output that evolved (expectedly) in the early postoperative period.
Fourth, the initial use of retrograde cardioplegia enabled optimal myocardial protection and thus maximized left ventricular performance. Last, treatment of the child's cardiac cachexia with protracted mechanical ventilation and alimentation, both parenteral and enteral, made an important contribution to his survival.
References
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