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Biomedical subjects

W S Pierce

Publications and source records attributed to W S Pierce.

At least 73 records · Page 4Linked to original sources
PubMed1985

Protamine-induced thrombocytopenia and leukopenia.

Protamine has been reported to cause thrombocytopenia and granulocytopenia. In this article, we report studies examining the relative contribution of protamine and heparin in the pathogenesis of this phenomenon, the dose-effect relationship, and the possible mechanism of cell loss. Protamine alone infused into experimental animals causes mild, transient granulocytopenia and thrombocytopenia. The sequential administration of heparin and protamine results in a more severe cytopenia lasting 30 to over 60 min. Organ scanning with 111In-labeled platelets shows a striking though transient accumulation of radioactivity in the lungs following heparin-protamine infusion. Platelet survival, however, is not shortened. Incubation of 125I-labeled protamine with blood cells in the presence of heparin results in tight binding of the drug to platelets and granulocytes. These observations suggest that protamine and heparin form a complex that binds to blood cells. The sequestration of coated cells in the lungs results in transient granulocytopenia and thrombocytopenia.

Animals↗
PubMed1985

Risks of mitral valve replacement and mitral valve replacement with coronary artery bypass.

One hundred thirty consecutive patients who underwent mitral valve replacement (MVR) or MVR with coronary artery bypass grafting (CABG) using cold crystalloid cardioplegic solution were analyzed to determine operative mortality and risk factors. Twenty-eight patients had mitral stenosis (MS), 37 had mitral regurgitation (MR), 37 had mixed MS and MR, 23 had MR with coronary artery disease (CAD), and 5 had MS with CAD. Preoperative pulmonary artery pressure, pulmonary capillary wedge pressure, and cardiac index were not different among groups, but patients with MR and CAD had a significantly higher left ventricular end-diastolic pressure (LVEDP) and a significantly lower ejection fraction than other groups. Mortality was 7.1% for patients with MS, 5.4% for MR, 8.1% for mixed MS and MR, 0 for MS with CAD, and 21.7% for MR and CAD. Overall mortality was 9.2%. Eleven patients had emergency operations for cardiogenic shock with a mortality of 45%. Nineteen additional patients in New York Heart Association (NYHA) Functional Class IV had MVR or MVR plus CABG with a mortality of 26%. Sixteen patients required intraaortic balloon pump assistance, and 9 survived. Four patients with MR and CAD required the left ventricular assist device, and 3 survived. Excluding patients who had emergency operations, overall mortality was 5.8%. Excluding patients who had emergency operations and patients in NYHA Functional Class IV, overall mortality was 2%. Factors associated with death were cardiogenic shock, NYHA Class IV, LVEDP greater than 15 mm Hg (16% mortality), and age greater than 60 years (15% mortality).

Adult↗
PubMed1985

Platelet release in coronary heart disease: effect of antiplatelet drugs and coronary artery bypass graft.

We report serial measurements of in vivo platelet release products beta-thromboglobulin and platelet factor 4 in 38 patients with coronary artery disease who underwent coronary artery bypass graft surgery. All patients were given dipyridamole preoperatively and both dipyridamole and aspirin postoperatively. Assays of plasma beta-thromboglobulin and platelet factor 4 were performed immediately before surgery, at discharge, and at follow-up visits. At initial evaluation, 22 patients with prior myocardial infarction had significantly elevated plasma beta-thromboglobulin levels (p = 0.0004). In the preoperative period, the use of dipyridamole caused some reduction of plasma beta-thromboglobulin and platelet factor 4, but the difference was not statistically significant. Six to 12 days after surgery, all patients had plasma beta-thromboglobulin concentrations higher than the preoperative levels despite the continued ingestion of dipyridamole and aspirin. At a follow-up visit, 30 to 133 days after surgery, only patients with previous myocardial infarction had beta-thromboglobulin levels higher than their preoperative values. However, compared with controls, all patients who underwent coronary artery bypass graft surgery had elevated plasma levels of beta-thromboglobulin in both the early and late postoperative periods. In this group of patients, successful revascularization of the myocardium, as indicated by relief of symptoms, did not completely inhibit platelet activation.

Adult↗
PubMed1984

Platelet survival and function in animals with prosthetic mitral valve: the effect of nafazatrom.

Thromboembolism remains a serious problem in patients with prosthetic heart valves. Previous studies documented a number of platelet abnormalities in such patients and correlated the occurrence of thromboembolic complications with short platelet survival. We have studied platelet survival and platelet aggregation in eight goats fitted with prosthetic mitral valves and repeated the studies following treatment with nafazatrom, a potent antithrombotic agent. Eleven survival studies in eight animals showed a platelet survival not significantly different from control (6.52 +/- 0.72 vs. 6.94 +/- 0.81 days). Following seven to ten days of oral drug administration, platelet survival in the test animals was 7.34 +/- 0.96 days, significantly longer than pretreatment results (p less than 0.01). Animals with the shortest pretreatment platelet survival achieved substantial prolongation of platelet life span following drug treatment. The drug caused no change in ex vivo platelet aggregation.

Administration, Oral↗
PubMed1984

Hemostatic abnormalities associated with prolonged ventricular assist pumping: analysis of 24 patients.

Bleeding remains a serious problem in patients with ventricular assist pumping (VAP). Clinical and hemostatic laboratory data in 24 patients who could not be separated from cardiopulmonary bypass (CPB) at the conclusion of open heart surgery and who underwent VAP for 54 to 610 hours were analyzed. The most important variable that correlated with the occurrence of severe bleeding was the duration of CPB: 5.2 +/- 1.6 hours in 13 patients with excessive bleeding, vs 3.6 +/- 1.1 hours in 11 patients with "acceptable" levels of bleeding (p less than 0.01). Moderate thrombocytopenia occurred in all patients but did not appear to be a major contributing factor to excessive bleeding. Disseminated intravascular coagulation (DIC) occurred in 12 patients, 4 of whom were in cardiogenic shock. DIC also correlated with time on CPB: 5.2 +/- 1.7 hours for patients with DIC, vs 3.7 +/- 1.1 hours for patients without DIC (p less than 0.01). No correlation was noted between the duration of VAP and the occurrence of DIC or bleeding.

Adult↗
PubMed1984

The compliance problem: a major obstacle in the development of implantable blood pumps.

The compliance problem represents a major obstacle in the development of implantable blood pumps. The motor-driven pumps are enclosed in an airtight casing with gas in the motor space. The trapped gas in the motor space either increases the load on the motor during systole or impedes blood sac filling. Potential solutions to the compliance problem include the use of a conventional blood pump with a compliance chamber, a blood pump with an isolated blood sac and accumulator, or a volume-compensated blood pump. Most experimental studies designed to investigate this problem have been performed with compliance chambers. An ideal compliance chamber should accept 100 ml gas with less than a 15-mm Hg increase in pressure and should automatically compensate for changes in atmospheric pressure. To date, two designs have been shown to be effective in laboratory and animal studies: a collapsible rectangular sac design developed by our group, and a lenticular chamber developed by Nosé and associates. Compliance chambers of the former design have now been employed to provide the required compliance for motor-driven assist pumps in long-term calf studies.

Assisted Circulation↗
PubMed1984

Mesoatrial shunt: a prosthesis modification.

The mesoatrial shunt is the indicated treatment in the Budd-Chiari syndrome when the inferior vena cava is occluded and not usable for the standard portasystemic shunts. As the mesoatrial shunt courses from the abdomen into the right side of the chest, it passes posterior to the xiphoid and sternum and frequently is compressed at this point. A prosthesis modification is reported whereby an exterior silicone rubber cuff is bonded to the Dacron or Gortex graft at the point at which it passes posterior to the sternum. This obviates the possibility of graft compression and should increase long-term patency.

Adult↗
PubMed1984

Should elective repair of coarctation of the aorta be done in infancy?

Our experience with the subclavian flap repair for coarctation of the aorta over the past 10 years includes 53 patients under 1 year of age. Of this group, 35 were newborn infants. All but two had an associated patent ductus arteriosus and 23 (66%) had associated intracardiac anomalies. All neonates had severe congestive heart failure and operation was carried out promptly after they were stabilized with diuretics and inotropic agents. Prostaglandin infusions have been essential to the care of many of these patients. Operative mortality was two of 53 patients (4%). No patient more than 4 days old operation has died, and concomitant pulmonary artery banding was performed in five infants with no deaths. Running nonabsorbable suture was used in 21 patients, interrupted nonabsorbable suture in 23, and continuous monofilament absorbable suture in the last nine. Mean follow-up time has been 46 months. Invasive follow-up studies, performed in 11 patients, have revealed residual systolic gradients of 5, 15, and 20 mm Hg in three and 0 mm Hg in one in whom continuous suture technique was used. The other seven had interrupted suture technique, and no gradient was present. Initial follow-up information for the group with absorbable suture repair suggests no residual gradients. No patient had significant upper extremity or hand morbidity. Eight patients had normal blood pressure and normal arm-to-leg gradients after exercise. When absorbable vascular suture is unavailable, an interrupted suture technique is superior to a continuous running repair. In view of the low operative mortality, the excellent growth of the repaired area, yet the likelihood of late development of cardiovascular disease (especially hypertension) if the repair is effected in childhood or adolescence, we favor prompt subclavian flap repair of coarctation of the aorta in all infants with or without symptoms. Concomitant pulmonary artery banding is seldom indicated.

Aortic Coarctation↗
PubMed1984

Pulmonary circulatory support. A quantitative comparison of four methods.

Profound right ventricular failure was produced in 16 goats by inducing ventricular fibrillation after the systemic circulation had been supported with a left atrial-aortic bypass pump. In each animal, four methods of providing pulmonary blood flow were compared quantitatively: passive flow through the pulmonary artery due to a right atrial to left atrial pressure gradient; pulmonary artery pulsation via a 40 ml intra-aortic type balloon within a 20 mm Dacron graft anastomosed to the main pulmonary artery; pulmonary artery pulsation via a 65 ml single-port, valveless, sac type pulsatile assist device; and right atrial-pulmonary arterial bypass via a valved pneumatic pulsatile pump. Average cardiac index of the 16 animals for each method was 31.1 +/- 12.9, 44.4 +/- 13.6, 64.3 +/- 16.9, and 102.0 +/- 20.7 ml/min/kg, respectively. Passive pulmonary artery flow alone provided inadequate pulmonary circulatory support. Addition of pulmonary artery pulsation via the intra-aortic balloon within a conduit increased cardiac index 13.3 ml/min/kg (43%) above passive pulmonary artery flow (p less than 0.0005); however, the cardiac index remained inadequate. Increasing pulmonary artery pulsation volume with a 65 ml sac device provided a 32.2 ml/min/kg (106%) increase in cardiac index above passive flow (p less than 0.0005) to a level that was marginally adequate. The valved right atrial-pulmonary arterial bypass pump increased cardiac index 70.9 ml/min/kg (228%) above passive pulmonary artery flow (p less than 0.0005) to a satisfactory level and is the recommended method of pulmonary circulatory support in profound right ventricular failure.

Animals↗
PubMed1984

Successful management of right ventricular failure with the ventricular assist pump following aortic valve replacement and coronary bypass grafting.

Right ventricular failure is an infrequent but potentially lethal complication of cardiac surgical procedures. We have successfully treated a patient with right ventricular failure with the use of a right ventricular assist pump (RVAP). This patient had aortic stenosis and coronary artery disease involving the circumflex and right coronary arteries. He also had chronic obstructive pulmonary disease with mild pulmonary hypertension (mean pulmonary artery pressure of 26 mm Hg) and evidence of mild right ventricular failure (right ventricular pressure of 40/14 mm Hg). Gated radionuclide angiography, performed preoperatively, showed that the right ventricle had normal wall motion. Right ventricular failure prevented discontinuation of cardiopulmonary bypass despite use of an intra-aortic balloon pump. The right atrial pressure was 20 mm Hg with a left atrial pressure of 8 to 10 mm Hg. Bypass was readily discontinued following implantation of the RVAP. Recovery of the patient's right ventricle was evaluated with serial determinations of right ventricular work. The RVAP was removed on the fifth postoperative day and the patient made a complete recovery. Postoperatively, gated radionuclide angiography demonstrated moderate recovery of right ventricular function. We suspect that the perioperative right ventricular failure was a result of unsatisfactory myocardial protection due to total occlusion of the proximal right coronary artery, which resulted in a maldistribution of the cardioplegic solution. This case demonstrates that right ventricular function can be restored following circulatory support with a mechanical assist device.

Aortic Valve↗