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Biomedical subjects

H L Walters

Publications and source records attributed to H L Walters.

At least 37 records · Page 2Linked to original sources
PubMed1996

Repair of an unusual type of total anomalous pulmonary venous connection.

A 9-day-old, 4.5-kg female infant was diagnosed with total anomalous pulmonary venous connections by echocardiography. The unusual nature of the pulmonary veins and their connections led to cardiac catheterization and angiography. Angiography demonstrated the left-sided veins connected, via a retropulmonary artery vertical vein, to the left inominate vein whereas the right-sided pulmonary veins connected to the right superior vena cava. We repaired this lesion uneventfully by creating a neo-common pulmonary vein and anastomosing this confluence to the left atrium.

Cardiac Catheterization↗
PubMed1996

Skeletal muscle ventricles: frontiers in 1995.

Skeletal muscle ventricles (SMVs) constructed from electrically conditioned latissimus dorsi muscle (LDM) may become an alternative for assisting the failing heart. Left and right heart circulatory assist using SMVs has been performed successfully in both acute and chronic animal models. The configurations used to connect SMVs to the circulation have included a left atrium to aorta bypass, a left ventricle apex to aorta bypass, aortic counterpulsators, a cavopulmonary bypass, and a right ventricle to pulmonary artery bypass. One SMV used as an aortic counterpulsator functioned effectively in the circulation for more than 27 months. Recent application of the pericardium to the SMV as an inner layer and design changes in the connection of the SMV to the circulation have reduced the risk of thrombus formation and SMV rupture. Although several problems have yet to be solved, the goal of the SMV as a permanent circulatory assist device without the limitation of an external power source seems within reach.

Animals↗
PubMed1995

Influence of a delay on latissimus dorsi muscle flap blood flow.

The regional and total blood flow of canine latissimus dorsi muscle flaps (LDMFs) were examined to study the effect of a delay procedure, ligation of the perforators, before complete flap elevation. The regional blood flow of the middle and distal regions of the nondelayed LDMFs was poor and significantly lower than the proximal region at rest. The regional blood flow during the exercise test was improved and significantly higher in the middle (62% increase) and distal regions (187% increase) of the delayed LDMFs as compared with the nondelayed LDMFs. The mean total blood flow of the delayed LDMFs was 14 mL.min-1.100(-1) g at rest, increased to 30 mL.min-1.100(-1) g during exercise tests with intermittent burst electrical stimulation, and was maximal at 40 mL.min-1.100(-1) g immediately after the exercise. The phasic arterial blood flow of the delayed LDMFs was inhibited during contraction at 9 mL.min-1.100(-1) g, whereas it was 44 mL.min-1.100(-1) g during relaxation. In contrast, the phasic venous blood flow was accentuated during contraction to 32 mL.min-1.100(-1) g compared with 16 mL.min-1.100(-1) g during relaxation.

Animals↗
PubMed1995

Pediatric cardiac surgical ECMO: multivariate analysis of risk factors for hospital death.

BACKGROUND: Extracorporeal membrane oxygenation (ECMO) has emerged as an effective technique for the mechanical support of many pediatric postcardiotomy patients with medically refractory cardiac failure. METHODS: We retrospectively reviewed the records of 73 pediatric patients with congenital heart disease who were placed on ECMO support between August 1984 and February 1994. The patients were divided into groups defined by the timing of ECMO cannulation relative to the time of operation. Group 1 patients (n = 7, 9.6%) were placed on ECMO preoperatively. Group 2 patients (n = 66, 90.4%) were a heterogeneous population placed on ECMO at any interval after cardiac repair. Subgroup 2A consisted of patients (n = 17, 25.8%) who could not be weaned from cardiopulmonary bypass and were converted directly to ECMO support immediately after repair. Subgroup 2B patients (n = 49, 74.2%) were cannulated postoperatively after an initial period of clinical stability. RESULTS: Hospital survival for all study patients (42/73) and for group 2 patients (38/66) was 58%. Only 4 group 2A patients (23.5%) survived their hospitalization compared with 34 group 2B patients (69.4%) (p = 0.001). Multivariate analysis identified elevated right atrial pressure after ECMO decannulation (p = 0.049) and, possibly, membership in group 2A (p = 0.061) as independent risk factors for hospital death. CONCLUSIONS: Extracorporeal membrane oxygenation is most effective in salvaging pediatric cardiac surgical patients who demonstrate medically refractory hemodynamic deterioration at some interval after being successfully weaned from cardiopulmonary bypass. The right atrial pressure after extracorporeal membrane oxygenation decannulation is an independent predictor of hospital death.

Cardiopulmonary Bypass↗
PubMed1995

Endothelial cell-lined skeletal muscle ventricles in circulation.

Skeletal muscle ventricles were constructed from the latissimus dorsi in six dogs by wrapping the muscle around a polypropylene mandrel. Jugular vein endothelial cells were harvested enzymatically and grown in tissue culture. After 3 weeks of vascular delay and 4 weeks of electrical conditioning, five skeletal muscle ventricles were seeded with 5 to 8 x 10(6) autologous endothelial cells by percutaneous injection of a cellular suspension into the lumen of the skeletal muscle ventricle; one skeletal muscle ventricle was injected with culture medium alone as an unseeded control. The autologous endothelial cells were all prelabeled with a lipid-bound cellular marker, PKH-26. After an additional 4 weeks of electrical conditioning, the mandrels were removed and the skeletal muscle ventricles were connected to the descending thoracic aorta and activated to contract during cardiac diastole at a 1:2 ratio with the heart. After 3 hours of continuous pumping, mean diastolic pressure was increased by 35% (58 +/- 7 versus 78 +/- 6 mm Hg, p < 0.05). At this time, the skeletal muscle ventricles were excised for histologic examination. Sections stained with hematoxylin and eosin revealed a continuous cellular layer lining the skeletal muscle ventricle; no cells were present on the lumen of the control skeletal muscle ventricle. All seeded skeletal muscle ventricles exhibited fluorescence as a result of the PKH-26 cellular marker. Immunofluorescent staining with antibodies to von Willebrand factor and ultrastructural analysis with an electron microscope confirmed the endothelial character of these cells lining the lumen of the skeletal muscle ventricles. The ability to create endothelial cell-lined muscular pumping chambers holds important implications for the resolution of thrombotic events in cardiac assist devices as well as toward the clinical application of skeletal muscle ventricles.

Animals↗
PubMed1994

Presentation, clinical features and outcome in different patterns of atherosclerotic renovascular disease.

Atherosclerotic renovascular disease (ARD) is an increasingly important cause of renal failure. However, important features of the clinical presentation are not fully described, and the outcome after intervention by angioplasty remains controversial. Ninety-four patients with ARD diagnosed at angiography were reviewed. Twenty-four patients were diabetic. Thirty-nine patients had unilateral renal artery stenosis or occlusion (group A), 28 had bilateral stenosis (group B), and 27 had unilateral occlusion plus contralateral occlusion or stenosis (group C). Two years after presentation, actuarial patient survival was 96%, 74.3% and 47.1% in groups A, B and C, respectively (p < 0.001 for all differences); actuarial renal survival in surviving patients was 97.3%, 82.4% and 44.7%, respectively (p < 0.001 for all differences). Percutaneous transluminal balloon angioplasty (PCTA) was performed in 74 patients. Renal function improved in only a minority of cases, but was stable in 73% of nondiabetic patients 12 months after PCTA. Angioplasty was less effective in diabetic subjects, with only 53.3% having stable renal function at 12 months follow-up. Renal and patient survival were strongly related to the initial angiographic findings. In non-diabetic subjects, PCTA resulted in stabilization of renal function for at least one year in nearly three-quarters of cases, which suggests a benefit from intervention in this disease whose natural history is otherwise of progression.

Adult↗
PubMed1994

Delayed sternal closure after neonatal cardiac operations.

We retrospectively compared the use of primary elective open sternum coupled with delayed sternal closure with the use of primary sternal closure in neonates after cardiac operations. Primary elective open sternum/delayed sternal closure was selectively used in patients who demonstrated hemodynamic or respiratory deterioration, or both, during an intraoperative trial of sternal closure; otherwise primary sternal closure was used. Primary elective open sternum was used in 55 (61.8%) and primary sternal closure in 34 (38.2%) of the 89 patients studied. Eleven (20%) patients having primary elective open sternum died compared with 5 (14.7%) patients having primary sternal closure (p = 0.6). Six (10.9%) of the patients with primary elective open sternum died before delayed sternal closure; the remaining 49 patients comprise the primary elective open sternum/delayed sternal closure group. The durations of mechanical ventilation (9.7 +/- 0.9 days [mean plus or minus standard error of the mean], median 7.7 versus 9.9 +/- 3.4 days, median 4.9; p = 0.0005) and hospital stay (21.1 +/- 1.4 days, median 17.7 versus 19.6 +/- 4.1 days, median 12.9; p = 0.004) were shorter in the primary sternal closure group. The overall morbidity and duration of inotropic support were not significantly different between the two groups, although seven (20.6%) of the patients with primary sternal closure did have to undergo delayed sternal reopening for refractory postoperative low cardiac output. There was one superficial wound infection in the primary elective open sternum/delayed sternal closure group. Primary elective open sternum/delayed sternal closure is an effective treatment for postoperative neonatal mediastinal compression for the following reasons: (1) the morbidity is low; (2) the mortality of the critically ill group of neonates in whom primary elective open sternum/delayed sternal closure was used was similar to that of the less critically ill primary sternal closure group; and (3) 20.6% of the primary sternal closure group eventually had to undergo delayed sternal reopening to treat refractory postoperative low cardiac output.

Cardiac Surgical Procedures↗
PubMed1992

The response to ischemia in blood perfused vs. crystalloid perfused isolated rat heart preparations.

With a research hypothesis that the behavior of blood perfused hearts was different from that of crystalloid perfused hearts, we tested the null hypothesis that the functional and metabolic status of blood-perfused (paracorporeal oxygenation) and Krebs-Henseleit (bubble oxygenation) perfused Langendorff isolated rat hearts is the same before, during and after global myocardial ischemia. Thirty isolated rat hearts were studied under identical conditions except that in equal numbers they were randomly assigned to either blood or crystalloid perfusion. In the blood perfused and crystalloid perfused hearts subjected to 22 min of normothermic ischemia and 30 min of reperfusion, mean systolic recovery was 72 +/- 3.9% (S.E.) and 20 +/- 10% (P = 0.001), respectively; coronary resistance increased 21 +/- 16% and 158 +/- 27% (P = 0.0003) (unadjusted for viscosity); mean water content after reperfusion was 82.0 +/- 0.43% and 86.7 +/- 0.42% (P < 0.0001), ATP content was 8.4 +/- 1.9 and 4.3 +/- 0.5 mumol/g dry wt (P = 0.08), and energy charge was 0.74 +/- 0.114 and 0.59 +/- 0.048 (P = 0.3). A major qualitative difference during reperfusion was spontaneous relaxation of contracture and rapid resumption of sinus rhythm in blood perfused hearts, in contrast to continued contracture and rise in intraventricular pressure in 9 of 10 crystalloid perfused hearts. One crystalloid perfused heart did not develop contracture, and its phenomena during reperfusion were similar to those of blood perfused hearts. The data support the research hypothesis, and suggest caution in extrapolating to blood perfused systems inferences from crystalloid perfused models. Better preservation of reactive hyperemia early in reperfusion may explain the better performance of blood perfused hearts.

Adenosine Triphosphate↗
PubMed1987

Peritoneal lavage and the surgical resident.

Peritoneal lavages performed in 161 patients who had sustained blunt (93 per cent) and penetrating (7 per cent) trauma were prospectively studied in order to assess our indications and technique, as well as to document the accuracy and complication rate in the hands of an Advanced Trauma Life Support trained resident staff. The most common indication for the performance of a lavage was blunt trauma to the abdomen associated with an altered mental status due to injury to the head or substance abuse. The semiopen technique was used 91.0 per cent of the time with a complication rate of 0.6 per cent. The open technique was used 9 per cent of the time on patients who had undergone previous limited abdominal operations, those who were pregnant, those with dilated intestine and for those patients with evidence of portal hypertension. Aspiration of greater than 10 milliliters of gross blood, an erythrocyte count greater than 100,000 per millimeter to the third power, or a white blood cell count greater than 500 per millimeter to the third power or an elevated amylase or bilirubin level in the lavage effluent, were the criteria used for a positive result in blunt trauma. The accuracy rate was 93 per cent with eight false-positive and three false-negative examinations. The sensitivity rate was 94 per cent and the specificity rate was 93 per cent. While most reported series classify lavage results as true-positive when intraperitoneal blood is found at exploration, even if secondary to trivial injuries which do not require surgical therapy (nontherapeutic laparotomy), we believe that these should be classified as false-positive results, as was done in this study. Computerized tomographic scanning may be more useful than peritoneal lavage in the evaluation of patients with pelvic fractures or other retroperitoneal injuries which often result in false-positive lavage. Peritoneal lavage is often an inaccurate indicator of isolated intestine and diaphragmatic or retroperitoneal injury. Given its simplicity, low complication rate and accuracy, peritoneal lavage can be safely performed by surgeons in training to evaluate the victim of trauma.

Abdominal Injuries↗
PubMed1985

The use of a low-osmolality contrast medium in hysterosalpingography: comparison with a conventional contrast medium.

Hexabrix 320 has been compared with Conray 280 in a randomised double-blind study of 97 patients undergoing hysterosalpingography. Although the lower osmolality and higher viscosity of Hexabrix should make it an ideal hysterosalpingographic agent, no differences were detected between the two contrast media, either in the incidence of side-effects or in radiographic image quality.

Abdomen↗
PubMed1980

125I-fibrinogen uptake following phlebography of the leg. Comparison of ionic and nonionic contrast media.

The incidence of venous thrombosis diagnosed with the 125I-fibrinogen uptake test was investigated in a prospective, randomized, double-blind study with the patient serving as his own control, using an ionic contrast medium (methylglucamine iothalamate 280) in one leg and a nonionic medium (metrizamide) in the other. The incidence of thrombosis was significantly lower with metrizamide (7%) than with methylglucamine iothalamate (28.6%). The authors conclude that metrizamide is the contrast medium of choice for phlebography.

Adult↗