Donald R. Sperling

Percutaneous transluminal angioplasty of congenital coarctation of the aorta

Two cases of successful dilatation of congenital coarctation of the aorta using the Grüntzig technique are reported. In a 3-week-old boy and an 11-month-old girl, systolic gradients across the narrowed areas were lowered from 50 to 8 mm Hg and from 23 to 8 mm Hg. Although the femoral pulses later disappeared in the younger patient, surgery was avoided. The second patients gradient has remained minimal for 8 months and no surgery has been performed.

Microporous Expanded Polytetrafluoroethylene Arterial Prosthesis for Construction of Aortopulmonary Shunts: Experimental and Clinical Results

A new microporous, expanded polytetrafluoroethylene arterial prosthesis was evaluated in dogs. The material appears to produce an adequate prosthesis for aortopulmonary anastomosis in animals and can conduct a high rate of blood flow. The graft has been used in 3 patients with pulmonary atresia aged 2 days, 2 months, and 6 months. Thus far all patients are well, growing, and have a loud shunt murmur. The desirable features of this type of anastomosis are presented.

In Vivo Determination of Renal Tissue Oxygenation During Pulsatile and Nonpulsatile Left Heart Bypass

Abstract Data favoring pulsatile over nonpulsatile left heart bypass are conflicting. To study this problem, renal cortical and medullary tissue oxygen availability (O 2 a) and total renal oxygen flow were compared with total renal oxygen consumption during four hours of pulsatile and nonpulsatile bypass in dogs. Although there was no difference in renal tissue O 2 a during the first two hours, thereafter the decrease in renal O 2 a was greater during nonpulsatile bypass; total renal blood flow was greater with pulsatile bypass, and at the given renal oxygen flow, renal oxygen consumption was greater during pulsatile bypass. These data, along with previous work, support the superiority of pulsatile bypass.

Ligation of the patent ductus arteriosus in newborn respiratory failure.

Patent ductus arteriosus (PDA) is commonly associated with respiratory disease in newborn infants and may require ligation. Surgical ligation of the PDA can be done in small infants with low operative risk and minimal complications. The outcome of patients after ligation depends primarily on the severity of the underlying pulmonary disease. One hundred fifty-one patients have undergone ligation in an eight-year period at this center. A simplified technique performed in the neonatal intensive care unit with the use of local anesthesia and conventional ventilator management is described.

Pseudoaneurysm of the Thoracic Aorta: A Late Complication of Umbilical Artery Catheterization

Pseudoaneurysm of the thoracic aorta developed in an infant eight months following neonatal catheterization of the umbilical artery. Infection and placement of a stiff polyvinyl chloride catheter in the thoracic aorta appear to be the etiological factors. Preoperative diagnosis was posterior mediastinal tumor, and pseudoaneurysm was not included in the differential. Dacron graft patch angioplasty repair using partial cardiopulmonary bypass was successful. Postoperatively the patient has done well with no pressure gradient. Pseudoaneurysm should be suspected whenever a mediastinal mass appears in children who have had thoracic placement of umbilical artery catheters.

Novel 23-base-pair duplication mutation in TSC1 exon 15 in an infant presenting with cardiac rhabdomyomas

Tuberous sclerosis (TSC) is a dominantly inherited disorder due to mutations at two gene loci, the TSC1 locus on chromosome 9q34 and the TSC2 locus on chromosome 16p13.3. The TSC2 and the TSC1 genes have now been cloned, enabling mutation analysis. We report results of mutation analysis in a sporadic case of TSC first identified in intra-uterine life on the basis of the presence of cardiac rhabdomyomas. Postnatally this infant was also found to have subependymal nodules on brain computed tomographic scan. Hypomelanotic macules were not detected neonatally or at 12 months of age. The specific TSC1 exon 15 mutation found in our patient has not previously been reported in cases of TSC. This mutation involves duplication of a 23-bp segment of DNA between two 9-bp repeated sequence elements within exon 15. These repeat elements are located between nucleotides 1892-1900 and between nucleotides 1915-1923 within the TSC1 gene sequence. It is likely that the presence of these two repeated elements predisposes to misalignment of DNA strands and unequal crossing over. The mechanism of origin of rhabdomyomas in TSC is reviewed. Loss of heterozygosity in the TSC gene regions has been reported in cardiac rhabdomyomas; however, these lesions are self-limiting in their growth. The basis for this self limiting proliferation is not clear. One interesting postulation is that cardiac rhabdomyomas may be due to delay or failure of apoptosis which occurs as part of the normal remodeling process in the heart.

Pulmonary artery pressure monitoring in persistent fetal circulation (PFC)

The use of the Swan-Ganz catheter to monitor pulmonary artery pressure in adults with cardiopulmonary failure has become commonplace. Our meager experience was with four neonates diagnosed as having persistent fetal circulation monitored by the use of this PA catheter. Tolazoline was infused directly into the pulmonary circulation via the catheter. Pulmonary artery pressure was temporarily reduced by tolazoline administration, with a marked increase in PaO2. More experience is required to define the role of the Swan-Ganz catheter in neonatal physiologic monitoring.

Hypothermia and Rewarming by Peritoneal Dialysis and Temperature-Controlled Inhalate

In 12 rabbits hypothermia and rewarming were induced with temperature-controlled circulating peritoneal dialysis in combination with temperature-controlled hypoxic and hypercapnic gas mixtures. The average cooling time necessary for the esophageal temperature to decrease from 37.7 degrees +/- 0.7 to 20.6 degrees +/- 1.0 degrees C was 81 +/- 34 minutes with a range of 41 to 150 minutes. The average warming time for esophageal temperature to increase from 20.6 degrees +/- 1.0 degrees C to 35.2 degrees +/- 1.8 degrees C was 90 +/- 35 minutes. Time of cooling was related to the proportions of inspired carbon dioxide and oxygen. In contrast to surface and bypass methods, esophageal and muscular temperatures agreed very closely, suggesting an absence of regional temperature gradients.

Tissue Oxygen Available as a Criterion for the Effectiveness of Continuous Positive Pressure Breathing

Summary: As little as 3–5 cm H2O increase in proximal airway pressure applied to normal lung reduces cardiac output. It is postulated that decreased pulmonary compliance in respiratory distress syndrome (RDS) acts as a barrier thus offsetting this effect. Since cardiac output is not routinely measured, severe reduction in it could accompany regression of disease while maintaining -the same airway pressure. This study was undertaken to determine whether tissue oxygen available (O2a) could be used to detect changes in perfusion during continuous positive pressure breathing (CPPB). CPPB was evaluated in 10 normal rabbits (C1 = 9.5 ± 1.8 cc/g at 25 cm H2O) and in 10 pulmonary-damaged rabbits (CL = 5.5 ± 1.4 cc/g at 25 cm H2O) produced by subjecting them to 100% O2. Airway pressure was increased from 0–15 cm H2O in 3 cm H2O increments at 10-min intervals. O2a and PaO2 were monitored continuously. In the normal group, O2a decreased at 3 cm H2O airway pressure, reaching 22% of control at 12 cm H2O, at which pressure PaO2 decreased. Breathing 100% O2 at this airway pressure increased PaO2 to 408 mm Hg, whereas O2a returned to 45% of control. In the experimental group, O2a decreased at 9 cm H2O airway pressure, at 12 cm H2O it was 36% of control at which pressure PaO2 decreased slightly. Breathing 100% O2 at this airway pressure increased PaO2 to 316 mm Hg, and increased O2a to 200% of control. These data indicate that with excessive airway pressure, muscle hypoxia may exist during systemic hyperoxemia and that a low compliance lung exerts a protective effect on O2a. Since changes in cardiac output during CPPB are compliance dependent, and since O2a is perfusion dependent, tissue oxygen available could provide a means of selecting optimal airway pressure during CPPB.Speculation: This study indicates that in the presence of normal PaO2 or every hyperoxemia, an excessive increase in airway pressure can produce a decrease in cardiac output and local oxygen supply to the tissues. The airway pressure required to produce optimal oxygenation without interference with cardiac output is lung compliance dependent. For the most efficient application of CPPB in clinical situations, measurement of physiologic variables which would reflect changes in perfusion in addition to systemic oxygenation are suggested.