L. Henry Edmunds

Patent ductus arteriosus in premature infants.

Abstract Patent ductus arteriosus (PDA) developed in 17 of 111 premature infants (birth weight 1750 g or less) born during a four-year period (15.3 per cent incidence). During that time we treated 29 such infants, 17 born at our own institution and 12 similar infants transferred from other hospitals. Sixteen of the 29 had cardiac catheterization, 10 had operative closure of the PDA, and 24 survived. When the PDA became evident, 23 infants had no pulmonary disease, were recovering from the idiopathic respiratory-distress syndrome (IRDS) or had chronic lung disease; all survived. In six infants with severe IRDS, onset of PDA was associated with a worsening of the pulmonary status; only one survived. We recommend cardiac catheterization and operative closure of the PDA in neonates when heart failure cannot be controlled medically. The prognosis is good in infants in whom onset of PDA is not associated with progressively worsening IRDS.

Surgical Closure of the Ductus Arteriosus in Premature Infants

During a 62-month period patent ductus arteriosus (PDA) was diagnosed in 88 premature infants with birth weights less than 1750 g. Twenty-one of these infants required operative closure of the PDA. Six infants had uncontrolled heart failure without associated pulmonary disease. Fifteen infants had severe idiopathic respiratory distress syndrome (IRDS) and required operation for deteriorating pulmonary function when heart failure developed. Twelve of these 15 infants weighed less than 1250 g at birth. The ductus arteriosus was ligated in 19 patients and was divided in two patients. The six infants without IRDS survived, and four are completely normal. Of 15 infants with IRDS eight had steady improvement in pulmonary function after operation. Three of these eight patients eventually died. In three infants pulmonary function improved slowly and in two patients pulmonary function did not improve after operation; all of these patients eventually died. Two patients died of peritonitis secondary to bowel ischemia. Of the five infants with IRDS who are alive, one is two months of age, two are moderately retarded in psychomotor development, and two, who developed hydrocephalus, are severely retarded. Although operation successfully controls heart failure in premature infants with PDA and IRDS, progressive pulmonary disease and the complications of extreme prematurity pre-empt good results in most of these infants.

Continuous positive airway pressure and pulmonary and circulatory function after cardiac surgery in infants less than three months of age.

Continuous positive airway pressure (CPAP) was used to support the ventilation of infants less than 3 months of age who had undergone thoractomy for cardiovascular surgery. The functional residual capacity, which was approximately 30 per cent of predicted at zero CPAP, increased 35 per cent in cyanotic and 33 per cent in acyanotic infants with the application of 5 mm Hg pressure. Increasing airway pressure from zero to 5 mm Hg increased PaO24 per cent in cyanotic and 13 per cent in acyanotic infants. There was no change in heart rate, respiratory rate, mean arterial pressure, pH or PaCO2 under similar circumstances, but central venous pressure increased 1.5 mm Hg in cyanotic and 0.8 mm Hg in acyanotic infants.

Valve Replacement for Bacterial and Fungal Endocarditis A Comparative Study

Twenty-eight of 143 patients treated for infective endocarditis had replacement of one or more cardiac valves within six months after the diagnosis was made. Twenty-two patients (16%) with bacterial endocarditis had operation, and six died in hospital. All six patients with fungal endocarditis required vale replacement, and one died in hospital. Uncontrolled or progressive heart failure was the indication for operation in all patients with bacterial endocarditis. When severe heart failure was present, 5 of 11 patients with bacterial endocarditis died in hospital, and only 1 of 3 patients with associated bacteremia survived. If blood cultures were sterile, the duration of preoperative antibiotic therapy did not correlate with hospital survival. None of the patients with bacterial endocarditis developed prosthetic infections, but two developed paravalvular leak.Massive emboli or persistent mycotic septicemia were the indications for valve replacement in patients with fungal endocarditis. Viable organisms were cultured from the excised valves in all of these patients in spite of preoperative amphotericin B for 30 to 140 days and negative blood cultures. Excision of the infected valve cured the infection in all patients.Five patients died 6 weeks to 36 months after operation. At the present time 16 patients remain alive 14 to 47 months after operation. Six of nine drug addicts are alive 15 to 27 months postoperatively.

Open mitral valvulotomy.

Abstract A five-year experience with routine open visualization of the mitral valve in 95 patients with mitral stenosis resulted in salvage of 53 valves and replacement of 42. The subvalvular structures were often thickened and fused, and meticulous dissection was necessary to produce adequate mobilization of the valve leaflets. An operative mortality of 1 death among the 53 patients undergoing commissurotomy attests to the safety of the procedure, but immediate functional results were not significantly better than with the closed method. Sufficient mobilization to produce a wide-open orifice in the relaxed state may be an important factor in the functional result.

Anastomoses between Aorta and Right Pulmonary Artery (Waterston) in Neonates

Abstract An anastomosis between the aorta and right pulmonary artery (Waterston operation) was constructed in 10 infants with severe cyanosis within 10 days after birth. Diagnoses after cardiac catheterization and cineangiography were pulmonary atresia with intact ventricular septum (five cases), pulmonary atresia with ventricular septal defect (two), pulmonary atresia with ventricular septal defect and transposition of the great arteries (one), tetralogy of Fallot (one) and tricuspid atresia with intact ventricular septum (one). One infant died five hours after operation and did not have a patent anastomosis. Four infants died six to 14 weeks after operation (two, who had associated lesions, died from chronic congestive heart failure, and two, who were seemingly well, died unexpectedly at home). Five patients are alive five to 23 months after operation. Four are asymptomatic, and one has intermittent respiratory problems. The Waterston operation is a successful, palliative procedure in newborn infants wi...

Cardiac Surgery in Infants Less than Six Weeks of Age

Sixty-one critically ill infants with congenital heart disease had operative treatment within 6 weeks of birth. Anatomic and physiologic diagnoses were established preoperatively by cardiac catheterization and angiography in all. A variety of palliative or corrective operations was performed to relieve specific hemodynamic burdens. Thirty-seven (61%) survived hospitalization, but 18 had one or more postoperative complications. At the present time, 29 (48%) are alive 9-45 months after operation. Although operative mortality and morbidity rates are high, none of these patients was expected to survive early infancy without operation.

Hemodynamic changes during complete heart block in the unanesthetized monkey

Abstract After surgically produced complete heart block, the hearts of six monkeys were paced electrically for five to eight days at their preoperative heart rates. Simultaneous measurements of regional blood flow and other hemodynamic variables were then obtained before and 15 minutes, two hours, and six hours after stopping electrical pacing and 30 minutes after restarting pacing. Fifteen minutes after stopping pacing heart rate, cardiac output, and systemic mean and diastolic pressures decreased and stroke volume increased. This pattern persisted throughout the six-hour period of idioventricular rhythm except that left ventricular end-diastolic and central venous pressures were increased only at 15 minutes and cardiac output was not significantly decreased at the six-hour period. During heart block the fraction of cardiac output received by the heart (except at six hours), brain, liver (hepatic artery), skull, spine, and adrenals was increased at the expense of skin, kidneys (initially), skeletal muscle, spleen, and pancreas. This pattern of regional redistribution of blood flow is similar to that found during hemorrhage and other conditions in which the sympathetic nervous system is stimulated. After pacing was restarted all the systemic variables measured returned to base-line levels, and the regional blood flows measured did not differ from those observed before the heart block.

Evaluation of Operative Left Ventricular Outflow Tract Lesions with a Fluid Impedance Plot

A hydraulic fluid impedance plot is produced by plotting instantaneous differential pressure against phasic blood flow across a vascular segment. This simple plot quantitatively and compactly describes the changes in flow resistance (impedance) throughout the entire cardiac cycle. Impedance plots were obtained before and after corrective surgery in patients with a variety of left ventricular outflow tract and aortic valve lesions. Although present techniques are still limited, impedance plots now provide quantitative measurement of flow resistance throughout the cardiac cycle in a variety of cardiac and great vessel lesions.

Evaluation of Hollow Fiber and Spiral Coil Membrane Oxygenators Designed for Cardiopulmonary Bypass in Infants

Fourteen 1.4 m2 hollow fiber and 23 1.5 m2 spiral coil membrane oxygenators that were designed for total cardiopulmonary bypass in infants were evaluated. Operating procedures and toxicity were studied during total cardiopulmonary bypass and one hour of circulatory arrest at 15° C (rectal) in four monkeys. Oxygen and carbon dioxide transfer, water loss, production of emboli, transmission of pulse waves, and pressure-flow relationships were studied at three different blood flow rates, at hematocrits of 25% and 40%, and at 25° C and 37° C during partial venoarterial bypass in 33 dogs. Linear regression equations were calculated for oxygen and carbon dioxide transfer and for pressure-flow relationships at the different flows, temperatures, and hematocrits. Rated flow (Rf), defined as the blood flow rate at which inlet O2 saturation of 65% increases to an outlet O2 saturation of 95%, was calculated for each oxygenator at hematocrit 40 (Rf 40) or hematocrit 25 (Rf 25). The hollow fiber oxygenator had a priming volume of 140 ml, an Rf 40 of 800 ml/min, and an Rf 25 of 1200 ml/min. The spiral coil oxygenator had a priming volume of 208 ml, an Rf 40 of 1400 ml/min, and an Rf 25 of 1800 ml/min. At Rf 40 and inlet pCO2 50 torr, the hollow fiber oxygenator transferred 8.9 ml CO2/100 ml and the spiral coil 5.7 ml CO2/100 ml. The performance of the two oxygenators differed, but both functioned very satisfactorily.