Myosin light chain efflux after heart transplantation in infants and children and its correlation with ischemic preservation time.

Serum levels of cardiac myosin light chain 1 after heart transplantation were studied in 24 infants and children who underwent heart transplantation between June 1990 and April 1991. The ages of the patients ranged from 4 days to 6 years 7 months (mean, 9.9 months), and their body weights ranged from 2.2 to 20 kg (mean, 5.6 kg). The ages of the donors ranged from 2 days to 8 years, 7 months (mean, 26.6 months), and their body weights ranged from 2.5 to 26 kg (mean, 11.4 kg). The donor heart ischemic time ranged from 90 minutes to 482 minutes (mean, 279 minutes). Peak myosin levels after heart transplantation showed significant correlation with the duration of graft ischemia (p < 0.01) and with diastolic cardiac function in the first posttransplant week (p < 0.05). Peak myosin levels did not correlate with systolic cardiac function, age of the donor, or age of the recipient. Myosin levels of the 15 patients with graft ischemic times exceeding 4 hours averaged 6.30 +/- 3.50 ng/ml. These levels were significantly higher than those of patients with graft ischemia lasting less than 4 hours (2.60 +/- 1.20 ng/ml; p < 0.01). Both of the values are higher than previously reported values of normal controls but lower than previously reported values of patients with myocardial infarction. Preservation techniques used for this series of transplant operations provided good clinical protection of the donor heart for up to 8 hours, although release of the cardiac myosin light chain fragment correlated with duration of graft ischemia. Cardiac myosin levels appeared to be a good indicator of heart graft damage during ischemic preservation. It remains to be determined at what level of myosin release (and, hence, at what duration of graft ischemia) irreversible myocardial damage, which might result in permanent functional compromise, occurs.

Transplantation and reanimation of hearts removed from donors 30 minutes after warm, asystolic 'death'.

OBJECTIVE: To test whether hearts from "dead," pulseless, asystolic donors could be transplanted and reanimated successfully using reperfusion manipulations. DESIGN AND INTERVENTIONS: Ten infant lambs (mean [+/- SD] weight, 4 +/- 1 kg) were anesthetized and pretreated with 50% dextrose, methylprednisolone, prostaglandin E1, and sublingual nifedipine. Five of these lambs were paralyzed; hypoxic asystolic arrest occurred 10 +/- 2 minutes later. Thirty minutes following asystole (mean, 40 +/- 2 minutes after paralysis) sternotomy was performed and the hearts were excised. Aortic blood gases were as follows: pH, 6.6 +/- 0.1; PCO2, 180 +/- 20 mm Hg; and PO2, 8 +/- 2 mm Hg. Donor hearts were given 30 mL/kg of Cardiosol (Water's Instrument Co, Danburg, Conn), a new cardioplegic agent, at 4 degrees C, and explanted into iced saline. The remaining five lambs then underwent cardiopulmonary bypass, were cooled to 20 degrees C, and hypothermic arrest was instituted. After excision of the recipient's heart, the donor heart was implanted in an orthotopic position. Total cold ischemic time was 1 hour 40 minutes +/- 10 minutes. The donor heart was retroperfused for 10 minutes with low-hematocrit, low-calcium blood via a coronary sinus catheter, then normal aortic inflow reperfusion was continued for 50 minutes. MAIN OUTCOME MEASURES: Removal of the cardiopulmonary bypass and measurement of hemodynamic parameters. RESULTS: One half hour after the bypass, mean systolic aortic pressure was 71 +/- 6 mm Hg; mean right atrial pressure was 6 +/- 2 mm Hg; mean left atrial pressure was 7 +/- 2 mm Hg; and mean pulmonary arterial pressure was 20 +/- 8 mm Hg. No inotropic drugs were given for postbypass blood pressure support. CONCLUSION: It is possible to transplant and reanimate hearts that have been dead for 30 minutes. When further developed, the use of donors who were not brain dead but allowed to die naturally could greatly increase the donor pool.

The Mustard procedure for correction of simple transposition of the great arteries before 1 month of age.

Since April 1976, 34 infants (25 male and 9 female) less than 1 month of age underwent a Mustard intraatrial baffle procedure for repair of simple transposition of the great arteries. Thirty patients were less than 2 weeks old and 19 patients less than 1 week (mean 7.8 +/- 6 days). The weights ranged from 2.6 to 4.4 kg (mean 3.4 +/- 0.4 kg). Rashkind balloon atrial septostomy was performed in the first hours or days of life in 29 patients. The average interval from balloon atrial septostomy to baffle repair was 3.9 days (range 2 hours to 14 days). Mechanical ventilation was required in eight patients preoperatively and prostaglandin E1 was infused in 17 patients to maintain ductal patency. In all patients, the Mustard procedure was performed with the use of deep hypothermic circulatory arrest, averaging 53 minutes (range 37 to 82 minutes). The duration of postoperative intubation and ventilatory support averaged 1.7 +/- 1.0 days (range 1 to 5 days). Inotropic drugs were used in 24 patients during a period of 1.4 +/- 1.3 days (range 1 to 6 days) postoperatively. There were no hospital deaths. Follow-up evaluation has extended from 1 month to 14 years (mean 3 +/- 3 years). One infant died 2 months postoperatively as a result of milk aspiration; no cardiac defects were found at the autopsy. A second infant died at 1 year with right ventricular and tricuspid valve dysfunction. Baffle complications occurred in 6 of the 32 survivors, including superior vena caval stenosis in 4, inferior vena caval stenosis in 1, and pulmonary venous obstruction in 3. Reoperations for baffle obstructions were performed in three patients (8.8%) and balloon angioplasties in two. One patient required permanent pacemaker implantation. Results with the Mustard procedure before 1 month of age show that it can be performed with negligible mortality and a low incidence of late complications at an age comparable to when arterial switching would be performed. Until long-term studies demonstrate superiority of arterial operations, the low operative mortality favors continued evaluation of the neonatal Mustard repair as a valid alternative to the arterial switch.

The effects of donor-recipient size disparity in infant and pediatric heart transplantation.

To determine the effect of heart donor and recipient size mismatches in infant and pediatric heart transplantation, we studied all 69 patients (age 1 day to 11 years) having 71 orthotopic heart transplants from 1985 to 1989. Patients were divided into three groups based on donor to recipient weight ratios. Group I comprised 13 heart transplants with a donor to recipient weight ratio less than 0.95 (mean 0.81, range 0.48 to 0.94); group II comprised 29 heart transplants with a weight ratio between 0.95 and 1.60 (mean 1.28); and group III had 27 heart transplants with weight ratios greater than 1.60 (mean 2.2, range 1.61 to 3.09). All chests were closed primarily. The cardiothoracic ratio by chest radiography was significantly larger in group III (p = 0.0002); 75% of group III patients had periods of lobar or complete lung collapse by chest radiography compared with 28% of group II and 19% of group I patients (p < 0.05). Despite this, there was no difference in the number of days of ventilator support for any group (p = 0.92). There was no difference in graft ischemic time or inotropic drug use among groups, nor were differences found in the cardiac systolic function parameters of left ventricular preejection time (p = 0.975), left ventricular ejection time (p = 0.975), left ventricular fiber shortening (p = 0.97), and left ventricular fractional shortening (p = 0.596). Thus despite a high incidence of transient lobar or complete lung collapse in high donor to recipient weight ratio transplants, large donor heart size produces very little clinical impairment in recipient lung function. Size mismatches do not influence cardiac systolic function. Overall, large size mismatches appear to be very well tolerated in infant and pediatric heart transplantation.