Hypoplastic left heart syndrome

Hypoplastic left heart syndrome (HLHS) is a prevalent congenital cardiac anomaly with high mortality.[1-3] The focus of perioperative management is on maintaining adequate pulmonary-to-systemic circulation ratio, and the inspiratory fraction of oxygen ([FIo.sub.2]) should be kept as low as possible.[1,4] Congenital diaphragmatic hernia (CDH) results in various manifestations of pulmonary hypertension, while the major problem encountered perioperatively is persistent fetal circulation (PFC). Therefore, neonates with CDH are treated with a high [FIo.sub.2]. As a result, the management of combined HLHS and CDH is very difficult. We herein report a patient with HLHS, CDH, and omphalocele and its perioperative management.

Case Report

The patient was female with a birth weight of 2500 g at 39-week 1-day gestation and uncomplicated vaginal delivery. Apgar score at 1 min was 9. Emergent operation was performed for omphalocele, but after the operation, her trachea could not be extubated due to cyanosis. Under mechanical ventilatory support at FIo[2] 0.45, peak inspiratory pressure (PIP) of 13 cm [H.sub.2] O, positive end-expiratory pressure (PEEP) of 3 cm [H.sup.2O], and 5 cycles/min of intermittent mandatory ventilation, the value for [PaO.sub.2] was 73.5 mm Hg and [PaCO.sup.2] was 38.1 mm Hg. Chest roentgenogram showed a right-sided diaphragmatic hernia with bowel gas in the right side of the chest (Fig 1). When echocardiography revealed HLHS, the patient was transferred to our hospital.

Mechanical ventilatory support with BP 200 was started immediately after admission to the intensive care unit (ICU). Settings were as follows: PIP, 15 cm [H.sub.2] O; intermittent mandatory ventilation (IMV), 30 cycles/min; and [FIo.sub.2], 0.4 [PaO.sub.2] and [PaCO.sub.2] were 68.2 and 37.2 mm Hg, respectively. To keep the patent ductus arteriosus (PDA) open, 50 ng/kg/min of prostaglandin E[1] was infused while 5 [mu]g/kg/min of dopamine was infused for circulatory support. When the patient was 10 days old, the right-sided diaphragmatic hernia was repaired by direct suturing of the defect. After the operation, pneumopericardium caused her circulatory and respiratory status to deteriorate, but she recovered from the episode as a result of insertion of a drainage tube.

Although right lung expansion was not good even after reconstruction of the diaphragmatic defect (Fig 2), oxygenation improved, and [PaO.sub.2] at [Flo.sub.2] was 66.5 mm Hg, although blood pressure fluctuated frequently. These conditions suggested a large pulmonary-to-systemic flow ratio that was accompanied by inadequate systemic perfusion. Palliative operation for HLHS, Norwood's operation, was scheduled when the patient was 27 days old. After the operation, her heart function became extremely impaired and she died of heart failure.

Discussion

Although HLHS occurs in 7.5 percent of infants with congenital heart anomaly[5], the incidence of associated extra-cardiac abnormalities is low in patients with HLHS[1]. In an analysis of 122 cases of HLHS, no patient was found to have associated gastrointestinal disease[6]. Furthermore, though CDH is sometimes associated with heart anomalies, its association with HLHS is rare[7, 8]. In the English literature, we found only nine cases of HLHS with CDH[7, 9]. However, to our knowledge, a combination of CDH, HLHS, and omphalocele had never been reported until our cse. The mortality of CDH associated with heart abnormalities is reportedly high[6, 9]. However, improvements in perioperative management have decreased the mortality rate for each of these diseases, and we considered it unacceptable to do nothing for our patient.

Since each of these three diseases is critical by itself, the treatment of the patient was very difficult. First of all, tracheal intubation and controlled mechanical ventilation were essential to prevent further deterioration of respiratory conditions due to aerophagia resulting in gastrointestinal distention. A nasogastric tube also had to be inserted for suction of gastric air and content and the distention of the gastrointestinal tract was controlled by frequent suction. The first operation was for omphalocele, and we believe this was right decision to prevent infection and loss of water and heat.

Perioperative problems for CDH include the prevention of PFC, while it is important to protect the patient from hypoxemia and stress. For this reason, a high [Flo.sub.2] is maintained. However, for an HLHS patient, [Flo.sub.2] should be kept as low as possible to maintain an adequate systemic blood flow. Fortunately, oxygenation of our patient was not so poor so that we were able to keep [Flo.sub.2] low. Furthermore, systemic circulation was controlled adequately without operating for HLHS, because elevation of pulmonary vascular resistance (PVR) due to hypoplastic lung was considered preferable to maintain an adequate pulmonary-to-systemic circulation ration. Therefore, right after delivery, prevention of PFC was considered the most important point, and the newborn had to be treated at a high [Flo.sub.2] even though she had HLHS. After a certain period, a ventilator had to be used to adjust the pulmonary-to-systemic flow ratio. For that purpose, [Flo.sub.2] was kept as low as possible.

The second operation was performed for the diaphragmatic defect to prevent aerophagia resulting in gastrointestinal distention in the thorax and deterioration of the respiratory condition. Timing of the operation for CDH is controversial, and recently some authors have reported good results by waiting until stabilization of pulmonary circulation, which reportedly takes a few days[10,11]. After that, severe side effects of the operation on pulmonary circulation may be prevented.

Palliative for HLHS was the last step. However, the timing was very difficult. The operation for both omphalocele and diaphragmatic hernia decreased the compliance of the abdomen and thorax. Therefore, the operation of HLHS was postponed until their compliance increased after the improvement of gastrointestinal edema. Although our patient's right lung was small even after diaphragmatic reconstruction, [PaO.sub.2] improved at low [Flo.sub.2] and low peak airway pressure was enough to maintain adequate alveolar ventilation. We judged that her respiratory condition had become stable and decided it was time to perform the operation for HLHS. The patient's circulatory condition became very poor after extracorporeal circulation, and she died of circulatory insufficiency. Mortality of palliative operation for HLHS remains very high, and the death of this patient is closely related to this high mortality rate.

We have reported a patient with CDH, omphalocele, and HLHS. The timing and selection of operative procedures were vital. Operations for CDH and HLHS should be performed after a sufficient decrease in PVR. In particular, the operation of HLHS should be postponed until gastrointestinal edema has improved and thoracic and abdominal compliance has increased after the operation for omphalocele and CDH. Unfortunately, our patient died after the operation for HLHS. However, correct perioperative management may have contributed to reducing the mortality risk for our patient to that of HLHS only.

References

[1] Pigott JD, Murphy JD, Barber G, Norwood WI. Palliative reconstructive surgery for hypoplastic left heart syndrome. Ann Thorac Surg 1988; 45:122-28 [2] Norwood WI, Lang P, Hansen D. Physiologic repair of aortic atresia-hypoplastic left heart syndrome. N Engl J Med 1983; 308:23-6 [3] Sade RM, Fyfe D, Alpert CC. Hypoplastic left heart syndrome: a simplified palliative operation. Ann Thorac Surg 1987; 43:309-12 [4] Hansen DD, Hickey PR. Anesthesia for hypoplastic left heart syndrome: use of high-dose fentanyl in 30 neonates. Anest Analg 1986; 65:127-32 [5] Fyler DC. Report of the New England Infant Regional Cardiac Program. Pediatrics 1980;65:376-471 [6] Greenwood RD, Rosenthal A, Nadas AS. Cardiovascular abnormalities associated with congenital diaphragmatic hernia. Pediatrics 1976; 57:92-7 [7] Kashani IA, Kimmons H, Valdes-Cruz LM, Swensson RE, Sahn DJ, Bloor C. Congenital right-sided diaphragmatic hernia and hypoplastic left heart syndrome. Am Heart J 1985; 109:177-78 [8] Firestone FN, Popper RW, Taybi H, Leonards R. Congenital diaphragmatic hernia and hypoplastic left heart: a case report and discussion. Pediatrics 1967; 40:329-33 [9] Snyder WH, Greaney EM. Congenital diaphragmatic hernia: 77 consecutive cases. Surgery 1965; 57:576-88 [10] Langer JC, Filler RM, Bohn DJ. Timing of surgery for congenital diaphragmatic hernia: is emergency operation necessary? J Pediatr Surg 1988; 23:731-36 [11] Cartlige PHT, Mann NP, Kapila L. Preoperative stabilization in congenital diaphragmatic hernia. Arch Dis Child 1986;61:1226-28

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