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Biomedical subjects

J A Waldhausen

Publications and source records attributed to J A Waldhausen.

At least 19 recordsLinked to original sources
PubMed1997

The early history of congenital heart surgery: closed heart operations.

The history of cardiovascular surgery before the development of open heart techniques is presented. Emphasis is placed on the creativeness and boldness of the visionary pioneers whose skills and determination led to the modern era of the routine surgical treatment of heart disease.

Cardiac Surgical Procedures↗
PubMed1996

Volume requirements for cardiac surgery credentialing: a critical examination. The Ad Hoc Committee on Cardiac Surgery Credentialing of The Society of Thoracic Surgeons.

New volume requirements for coronary artery bypass grafting are being imposed on cardiac surgeons by hospitals, managed care groups, and others. The rationale for this is unclear. The available literature as well as additional sources relating volume and outcomes in cardiac surgery were extensively reviewed and reexamined. There are no data to conclusively indicate that outcomes of cardiac operations are related to a specific minimum number of cases performed annually by a cardiac surgeon. Each cardiothoracic surgeon should participate in a national database that permits comparison of his or her outcomes on a risk-adjusted basis with other surgeons. Until conclusive data become available that link volume to outcome, volume should not be used as a criterion for credentialing of cardiac surgeons by hospitals, managed care groups, or others. Instead, each surgeon should be evaluated on his or her individual results.

Cardiac Surgical Procedures↗
PubMed1993

Improved recovery of immature myocardium with L-glutamate blood cardioplegia.

Enhancement of myocardial recovery with glutamate-enriched cold blood potassium cardioplegia (BPC) was evaluated using an isolated working heart model. Three groups of hearts from immature rabbits were subjected to 20 minutes of warm (37 degrees C) ischemia to allow energy depletion, followed by 90 minutes of hypothermic (10 degrees C) ischemia. Myocardial protection provided during hypothermia consisted of cardioplegia infusion, at 50 mm Hg every 30 minutes at 4 degrees C, of either St. Thomas' Hospital solution (group 1, n = 6), oxygenated BPC (group 2, n = 7), or oxygenated BPC enriched with 20 mmol/L L-glutamate (group 3, n = 7). Percent recovery of aortic flow was 87.6% +/- 6.3% (results expressed as mean +/- standard error of the mean) in group 3, which was significantly better than for either group 1 (63.4% +/- 4.0%) or group 2 (47.0% +/- 3.5%) (p < 0.05 by analysis of variance). Group 3 hearts had significantly better recovery of myocardial energy stores (mumol/g dry weight) compared with group 1 or 2 hearts: adenosine triphosphate, 17.8 +/- 1.1 versus 12.4 +/- 1.5 and 12.1 +/- 0.4; creatine phosphate, 25.9 +/- 1.8 versus 17.8 +/- 1.8 and 20.3 +/- 0.7; and glycogen, 140.7 +/- 12.6 versus 98.7 +/- 9.9 and 60.7 +/- 9.9 (p < 0.05). Glutamate-enriched BPC provided excellent myocardial protection after ischemia in this immature model, and this study quantitatively supports the use of glutamate-enriched BPC in neonatal clinical practice.

Animals↗
PubMed1993

Results of surgical repair of congenital supravalvular aortic stenosis.

Our experience with congenital supravalvular aortic stenosis dates from 1977 to 1991. Thirteen patients, aged 2 days to 38 years (mean 7.6 years, median 3.8 years), had surgical repair of the lesion. The preoperative peak-to-peak systolic gradients ranged from 25 to 110 mm Hg (mean 64 mm Hg). Four patients had trace to mild aortic insufficiency. Surgical repair was accomplished by several techniques that have evolved over time. There was one death in a 2-day-old neonate who also had severe hypertrophic cardiomyopathy. The 12 survivors had postoperative gradients of 0 to 30 mm Hg (mean 10 mm Hg) in the supravalvular region. The mean reduction in gradient was 48 mm Hg. A new technique employing all autologous aortic tissue is described.

Adolescent↗
PubMed1993

A long-term ventricular assist system.

An implantable, electrically powered pump that will provide tether-free circulatory support is being developed. The blood pump consists of a seamless polyurethane sac within a polysulfone case. Björk-Shiley Monostrut valves provide unidirectional flow. The blood sac is compressed by a pusher plate with a stroke of 1.9 cm and actuated by a brushless direct-current electric motor and motion translator. The current unit is completely sealed, and inductive coupling techniques provide the electrical energy. The system has an implantable electronic control system as well as a battery that provides 30 minutes of operation when the external coil is disconnected. During normal operation, however, the pump is powered by a portable battery pack or by house current. The unit can pump 8.5 L/min at physiologic pressures. Twenty-six animals have had circulatory support for a period of more than 1 week. The average period of pumping was 62 days; the longest was nearly 8 months. Experiments were terminated in 18 animals because of pump-related problems and in 8 because of biologically related problems. Studies to date are very encouraging and suggest that, with further refinement, a reliable 2-year assist pump that will have important clinical application can be developed.

Animals↗
PubMed1992

The Fontan operation in infants less than 2 years of age.

Young age remains a reported risk factor for a successful Fontan operation despite improved survival rates. Since March 1978, the Fontan operation has been performed in 47 patients. To avoid a primary or secondary palliative shunt, an early Fontan procedure (Group 1: mean age 1.5 +/- 0.5 years, range 0.6 to 2) has been performed in 17 children with the outcome similar to that of the remaining 30 older patients (Group 2: mean age 7.5 +/- 5 years, range 2.4 to 23 years). Preoperatively both groups had acceptable hemodynamic status for a successful Fontan result. Operative variables including cardiopulmonary bypass time, aortic cross-clamp time and core temperature were similar between groups and did not affect mortality. The postoperative mortality rate including early surgical (0% vs. 13%, respectively), late (18% vs. 12%) and total (18% vs. 23%) was similar between Groups 1 and 2 (p greater than 0.05). Immediate postoperative arrhythmias were more frequent in Group 1 (71% vs. 25%, p less than 0.01) with no related mortality, while late arrhythmias occurred with equal frequency (29% vs. 39%, p greater than 0.05). Group 1 infants required a longer hospital stay (22 +/- 9 vs. 14 +/- 5 days, p less than 0.01). Thus, young age is not a risk factor for successful outcome of the Fontan operation in patients with acceptable preoperative hemodynamic status. An early Fontan operation may also avoid prolonged palliative procedures and their potential deleterious effects.

Age Factors↗
PubMed1992

Coarctation of the aorta in infants: does the aortic arch grow after repair?

Infants with coarctation of the aorta frequently require a corrective operation during the first year of life. These patients frequently have a smaller than normal transverse aortic arch. Despite good repairs with different techniques, the proximal transverse aortic arch often remains smaller than normal. The hemodynamic molding theory predicts that growth of the aortic arch should occur when normal flow is established through the aortic arch. Preoperative and postoperative aortograms were reviewed in patients who underwent subclavian flap aortoplasty for the repair of coarctation. Patients were divided into two groups. Subclavian flap aortoplasty was performed at 1 month of age or earlier in group I, and at more than 1 month but less than 1 year of age in group II. Aortograms performed in patients without coarctation were used as age-matched controls (group III). The transverse aortic arch in groups I and II did grow and were compared with the control group. Group I patients achieved more growth than those in group II. No aortic arch gradients were present at postoperative follow-up.

Age Factors↗
PubMed1991

End-to-end repair of aortic coarctation using absorbable polydioxanone suture.

Based on previous laboratory work, we have used polydioxanone absorbable suture in a variety of vascular and cardiac repairs in pediatric patients. However, some investigators have expressed concern about the potential for aneurysm formation at the anastomotic site. Between March 1983 and June 1989, 15 patients (7 male, 8 female) aged 2.5 months to 9.2 years (mean, 3.7 years) had resection of coarctation of the aorta and end-to-end anastomosis with polydioxanone absorbable suture. Thirteen patients have returned for routine postoperative evaluation, the follow-up time ranging from 11 to 49 months (mean, 23 months). Noninvasive two-dimensional, pulsed-wave Doppler and color echocardiography and magnetic resonance imaging studies demonstrated good anatomical repair and no anastomotic aneurysm formation or residual coarctation of the aorta in any patient after end-to-end anastomosis with polydioxanone. In summary, this intermediate follow-up study has revealed no vascular complications related to the repair of coarctation with absorbable polydioxanone suture.

Abnormalities, Multiple↗
PubMed1991

Age-related changes in the efficacy of crystalloid cardioplegia.

Recent work has shown that multi-dose St. Thomas' Hospital cardioplegia solution (STHC) may not provide reliable protection of the neonatal myocardium. We have used an isolated working heart model to study the age-related development of this observation. Sets of eight hearts from 2-, 4-, 6-, and 8-week-old rabbits were subjected to 90 min of ischemia at 10 degrees C. STHC was infused at 30-min intervals in a dose of 10 ml/kg. There were no differences in the preservation of ATP stores during ischemia among the groups. The percentage recovery of preischemic mean aortic pressure, left atrial pressure, and heart rate were not different among groups, but the percentage recovery of aortic flow (AF) (expressed as means +/- standard error of the mean) was significantly lower in the 2- and 4-week hearts (44.1 +/- 8.2 and 66.2 +/- 7.7%) than in the 6- and 8-week hearts (93.0 +/- 6.4 and 97.6 +/- 4.7%). We have confirmed that the use of multi-dose STHC impairs recovery of ventricular function in the neonatal rabbit heart. This effect, however, diminishes rapidly as the immature animal develops and is not present by 6 weeks of age. Additional experimentation is necessary to identify those aspects of the developing myocardium that account for these observations.

Aging↗
PubMed1990

Results of aortic anastomoses made under tension using polydioxanone suture.

After early repair of congenital cardiovascular defects, such as coarctation of the aorta, late stenosis may become a problem. Use of absorbable sutures has been shown to be superior to use of nonabsorbable sutures in allowing growth of an anastomotic site along with the individual. Some concern has been raised, however, about the potential for aneurysm formation at the site of anastomosis when absorbable sutures are used. This study was undertaken to observe the effects of longitudinal tension on anastomoses made with absorbable polydioxanone suture in growing animals. Six piglets (aged 3 to 4 weeks) underwent a 1-cm resection of the infrarenal aorta and reanastomosis with polydioxanone suture. One animal died prematurely of respiratory illness. The 5 remaining animals were killed after 6 months. The excised aortas demonstrated no stenosis, no dilatation, and no burst-test failure to 250 mm Hg. Histological examination showed disrupted elastic laminae without thinning of aortic wall in all samples of aorta. We conclude that polydioxanone suture is a suitable suture material for vascular anastomoses made under tension where growth of the anastomotic site is expected.

Anastomosis, Surgical↗