Prostaglandin E1 as an adjunct to emergency cardiac operation in neonates.

Prostaglandin E1 (PGE1) has been used prior to operation in 28 neonates (0 to 30 days) with congenital heart disease (CHD). The patients were divided into two groups. Group I consisted of 19 neonates with CHD resulting in marked cyanosis. Thirteen patients had pulmonary atresia, three had tetralogy of Fallot, and three had complex defects with pulmonary stenosis. All patients were markedly hypoxemic. The average oxygen saturation was 41%. PGE1 infusion, 0.1 mcg/kg/min, was successful in 17 of 19 patients, as it resulted in an increase in oxygen saturation from 41% to 79%, average increase 38%. Two patients did not respond to PGE1 infusion. One was 30 days of age and the other had no patient ductus arteriosus. All of the patients underwent a palliative shunt procedure. There were three hospital deaths in this group. No patient died of hypoxemia. Group II consisted of nine patients whose CHD was predominantly that of aortic obstructive disease with clinical manifestations of cardiac failure, hypoperfusion, and acidemia. Six of these patients had complicated coarctation of the aorta. Three patients had interruption of the aortic arch. The pH of these patients averaged 7.19. PGE1 infusion resulted in improvement of the pH to average of 7.37, improvement of congestive heart failure, and reappearance of femoral pulses. One patient failed to respond. All patients in Group II underwent operation. There were three hospital deaths in this group. No patient died intraoperatively. PGE1 infusion is a valuable aid to surgical treatment of desperately ill neonates with both cyanotic and acyanotic forms of CHD.

Systemic-Pulmonary shunts inneonates and infants using microporous expanded polytetrafluoroethylene: immediate and late results.

Thirty infants with various types of cyanotic congenitl heart disease underwent systemic-pulmonary artery shunts with a microporous polytetrafluoroethylene (PTFE) graft between May, 1976, and July, 1979. Sixteen of them were less than 1 month old, and the average age of the neonates was 5.3 days. There were no operative deaths and 5 hospital deaths, 2 related directly to the shunt. Five patients required early revision of the shunt. Relief from cyanosis was achieved in each patient. Twenty-five patients have been followed up to three and one-half years. There have been 2 late deaths and one late occlusion of the shunt. One patient outgrew the shunt and required secondary shunting procedures. Three of 30 patients have evidenced mild congestive heart failure, which has responded to digitalis. Because of the reliability and excellent late patency of the PTFE prosthesis, we consider it to be superior to a central or Potts shunt for relief from cyanosis in the neonate and infant, and as reliable as a Blalock-Taussig shunt.

Role of the renin-angiotensin-aldosterone system in hypertensive children with coarctation of the aorta.

To investigate the role of the renin-angiotensin-aldosterone system as a cause of hypertension, 20 hypertensive patients with coarctation of the aorta were studied during normal and low sodium intake and after diuresis with flurosemide. Eight patients with essential hypertension and 13 control subjects were similarly studied. Plasma renin activity values in patients with coarctation were similar to those in patients with essential hypertension and in control patients during normal and low sodium diets. However, after the administration of furosemide, plasma renin activity values were significantly higher in the patients with coarctation than in the other two groups (P less than 0.005 and less than 0.01, respectively). The values for urinary aldosterone, plasma volume and extracell fluid volume (bromide space) were increased in patients with coarctation during both normal and low sodium intake. These renin and aldosterone responses and body fluid spaces in patients with coarctation suggest that their hypertension resembles a one-kidney Goldblatt model. The data help to better define the role of the renin-angiotensin-aldosterone system in the hypertension of coarctation and thus may help guide the clinician in therapeutic interventions.

Allograft renal-artery stenosis: increased peripheral plasma renin activity as an early indicator of uncontrollable hypertension.

We measured indices of the renin-aldosterone system and body-fluid spaces in 11 adolescents who had received a renal transplant after removal of their own diseased kidneys. None had hypervolemia but 6 had hypertension. Renal angiography revealed greater than 50% luminal occlusion by allograft renal-artery stenosis (RAS) in only the 3 patients who had severe hypertension refractory to conventional medical therapy. Excessive peripheral plasma renin activity (PRA) distinguished these patients from those who had less severe stenosis or normal angiogram, and diuretic stimulation heightened the PRA differences. We conclude that significant allograft RAS does not necessarily act like a typical single-kidney Goldblatt model until after volume depletion. Our findings indicate that peripheral PRA values can be used to assess the degree of graft ischemia clinically. This permits early identification of patients who have severe RAS that probably will be difficult to control medically, and, therefore, should be followed closely with a view of reconstructive vascular surgery before further deterioration of renal function.

Assessment of the cardiovascular system in conjoined thoracopagus twins.

The thoracoomphalopagus conjoined twins comprise 75% of all conjoined twins. In the assessment of the organ systems of the twins, the cardiovascular system is important since union of this system in the twins has occurred in 75% of the cases. Of the five cases reported here, two had separate hearts and vessels with a common pericardium only. Two twins were joined at the right atrial level. The fifth pair were connected at both atrial and ventricular levels. It has been suggested that the presence of two separate QRS complexes in the ECG indicates complete separation of the two hearts. Case 4 shows that even in the presence of atrial union, the existence of an atrioventricular block in one twin may produce a very slow heart rate, while the other twin may have a normal rate that will not influence the ventricular rate of the other. In our experience, angiocardiography has been the most useful diagnostic procedure.

Hemodynamic studies in children four to ten years after the Mustard operation for transposition of the great arteries.

Fourteen patients have been studied hemodynamically 4-10 years (mean 5.5 years) after the Mustard operation for transposition of the great arteries. Investigation was directed principally at 1) the detection of baffle obstruction by catheterization of the pulmonary veins (PV) and venae cavae and recording of simultaneous right ventricular (RV) and pulmonary capillary wedge pressures (PCW); 2) the detection of intra-atrial baffle leaks by dye curves and selective angiography; 3) the assessment of RV and LV function by calculating peak VCE (dp/dt/28p) from high fidelity recordings in 11 patients. Severe baffle obstruction to the PV return was found in only one patient. The others had no or minimal gradients between RV end-diastolic and PCW pressures (mean 1.3 +/- 0.69 mm Hg). Cardiac output was normal at rest (4.1 +/- .22) and increased to 7.1 +/- .62 L/min/m2 (+73%) but the gradient between the RV end-diastolic and PCW pressures remained insignificant (2.2 +/- 1.13 mm Hg). No evidence of caval obstruction was found in any patient. Baffle leaks were found in five patients with mild bidirectional shunting. All arterial oxygen saturations were above 90%. Mild tricuspid regurgitation was demonstrated in two patients by RV angiography and was absent in 12 others. The contractility index peak VCE averaged 1.87 +/- .122 sec-1 for the RV and was significantly lower in the LV (1.53 +/- 1.35 SEC-1, P less than 0.01). Only one patient presented significantly decreased RV contractility with a peak VCE of 1.07 sec-1 and poor contraction on the RV angiogram. These data indicate that the long-term prognosis after the Mustard operation should be good in most patients and that the right ventricle is capable of functioning at the level of contractility of a normal left ventricle.

Congenitally corrected transposition of the great arteries. A clinical study of 101 cases.

The anatomy, natural history, clinical features and symptomatology of 101 cases of congenitally corrected transposition of the great arteries (C-TGA) diagnosed over a 20-year period at Hospital for Sick Children, Toronto, Ontario, is reported. Only 1 patient had no association lesion and only 14 an intact ventricular septum. Pulmonary stenosis was present in a little more than half of the patients. Left A-V value involvement existed in 21 patients. In spite of the hich incidence of associated lesions with prognosis was better than expected. Seventy-six patients were alive at the end of the study, no one being critically ill. No death occurred among the patients with intact ventricular septum. Patients with pulmonary stenosis as a group developed symptoms later, were less handicapped and had a better prognosis than those without a pulmonary stenosis. One third of the patients had dysrhythmias. Eight patients having a 3rd degree AV-block. Auscultatory findings were not of too great a help when diagnosing C-TGA. Forty-seven patients had a single second sound, of these 37 had pulmonary stenosis. In 60% of the patients, where information was available, the second sound was reported to be of normal intensity. Our surgical experience is documented and discussed. Palliative procedures were done with successful results and low mortality. Totally corrective procedures were performed in 9 patients with 4 deaths.

Pulmonary arterial wedge and left atrial pressures and the site of hypoxic pulmonary vasoconstriction.

The pulmonary vascular response to breathing 5% oxygen in nitrogen was studied in anesthetized, artificially ventilated dogs. The pulmonary arterial (Pa), pulmonary arterial wedge (PW), left atrial (LAP) pressures and pulmonary blood flow (Q) were monitored. The pulmonary arterial catheter was wedged at the mid-lung level. At 10 min of hypoxia, Pa-PW pressure gradient increased while the PW-LAP gradient did not change significantly. The PW and LAP were significantly correlated during room air breathing (r=0.832) and during hypoxia (r=0.980). The calculated resistance from the pulmonary artery to the wedged catheter (Pa-Pa/Q) increased and the calculated resistance from the wedged catheter (Pa-Pw/Q) did not change significantly. These findings indicate that the mean LAP and PW pressures are not significantly different during severe hypoxia, and that the increase in pulmonary vascular resistance during hypoxia is due to constriction of the large precapillary vessels.

The effect of increased pulmonary blood flow on the pulmonary vascular bed in pigs.

Increased pulmonary blood flow was produced in 1-month-old piglets by means of left pneumonectomy, arteriovenous fistulas in the neck, and a combination of both. Physiologic and histologic studies of the pulmonary vascular bed were done 1-9 months after operation. A progressive, moderate increase in pulmonary artery (PA) pressure was observed, especially between 1 and 6 months after surgery. This was flow related, i.e., the group with the highest flow (pneumonectomy plus fistula) was found to have the most prominent increase in pressure. Mean Pa pressure at 6 months was 28.7 +/- 0.07 mm Hg in this group, vs 24.4 +/- 0.48 mm Hg in the group with pneumonectomy alone and 17.2 +/- 0.48 mm Hg in controls (P less than 0.01). The pressure response to hypoxia in pigs with high pulmonary blood flow was not different from that found in control animals. Histologic studies revealed that small arteries and arterioles of pigs with high pulmonary blood flow had a decreased relative wall thickness because of dilation up to 6 months follow-up. This was flow related, the group with the highest flow having the lowest wall thickness to vessel diameter ratio; relative wall thickness (in percentage of the vessel diameter ) at 6 months was 6.1 +/- 0.44% in pigs with with pneumonectomy plus fistula, vs 9.6 +/- 0.40% in the group with pneumonectomy alone and 11.2 +/- 0.61% in controls (P less than 0.01). In the group with the highest flow, thick walled arterioles appeared at 9 months follow-up, scattered among dilated ones; between 6 and 9 months after operation, ranging from 6.1 +/- 0.44% to 11.3 +/- 0.73% (P less than 0.01). In five animals with high flow, the right PA (main branch) showed patchy intimal thickening, small cystic spaces filled with mucopolysaccharides in the media, and muscular hypertrophy.