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Biomedical subjects

W S Pierce

Publications and source records attributed to W S Pierce.

At least 55 records · Page 3Linked to original sources
PubMed1989

Toward an implantable artificial heart. Experimental and clinical experience at The Pennsylvania State University.

The number of patients who would be candidates for replacement of their failing native heart with an artificial device increases every year. A multidisciplinary group at The Pennsylvania State University is working toward the development of a reliable, totally implantable artificial heart. Initial work resulted in a pneumatic total artificial heart that has performed well in animal implants and has been used clinically in three patients as a temporary bridge to cardiac transplantation. Although pneumatic total artificial hearts have demonstrated utility as temporary mechanical circulatory support devices, attempts at permanent implantation by other groups have been fraught with complications. Because of the suboptimal performance of the pneumatic devices used for permanent implantation, the authors' groups at Penn State is developing n electric motor-driven total artificial heart with encouraging results in calf implants. This artificial heart of the future will use a transcutaneous energy transmission system that will obviate the need for percutaneous lines. Thus, the patient will be provided with as near a normal life-style as possible. At present the technology is at hand to implant an electric blood pump system that should provide a reasonable life-style and function reliably with minimal care. Ongoing cooperative experimental efforts will help to provide the answers necessary to make this system ready for clinical use.

Animals↗
PubMed1989

Hemostatic abnormalities in two patients implanted with total artificial hearts.

Patients implanted with total artificial hearts (TAH) suffer frequent thromboembolic complications. The authors report results of continuous monitoring of multiple hemostatic parameters and autopsy findings in two patients implanted with TAH. Case 1 who used a TAH for 10 days and then underwent orthotopic transplantation died of fungal infection 7 days later. At autopsy, mycotic and nonmycotic thrombi were found in the brain, kidneys, spleen, and large bowel. Case 2, who survived 396 days with a TAH, suffered multiple thrombotic episodes despite adequate anticoagulation with warfarin. Autopsy revealed widespread thrombotic lesions mostly in the brain and lungs. Both patients had markedly elevated plasma beta-thromboglobulin and fibrinopeptide A levels throughout their survival, indicating sustained activation of platelets and coagulation secondary to blood contact with artificial surface. Other factors such as infection, liver damage, and acute pancreatitis might have also contributed to activation of hemostasis. As used in the authors two patients, antiplatelet drugs and warfarin seem to be ineffective in preventing artificial heart-related thromboembolic complications.

Adult↗
PubMed1988

Heterotopic prosthetic ventricles as a bridge to cardiac transplantation. A multicenter study in 29 patients.

Heterotopic prosthetic ventricles were used to support the circulation in 29 candidates for heart transplantation who were expected to die before procurement of a donor heart. Twenty-one of these patients (average age, 36 years) underwent successful transplantation after 8 hours to 31 days of circulatory support. The other eight patients died because their condition could not be stabilized for transplantation, despite restoration of blood flow. Fourteen patients received biventricular support; 15 received only left ventricular support, with pharmacologic assistance of right heart function. Before transplantation, blood flow from the left prosthetic ventricle averaged 2.8 +/- 0.4 liters per minute per square meter of body-surface area, and from the right prosthesis 2.4 +/- 0.4 liters, as compared with an average flow of 1.6 +/- 0.5 liters per minute per square meter before implantation. Of the 21 patients who received heart transplants, 20 were discharged from the hospital after a median of 31 days. Nineteen patients were alive at 7 to 39 months, and 11 of the first 12 were alive at one year. We conclude that heterotopic placement of prosthetic ventricles as a bridge to transplantation provides an effective method of temporarily supporting cardiac function in critically ill patients without removing the natural heart. The early survival rate after transplantation is similar to that with elective cardiac transplantation.

Adolescent↗
PubMed1988

Staged cardiac transplantation. Total artificial heart or ventricular-assist pump?

Because of donor organ unavailability, staged cardiac transplantation has been performed in eight patients with The Pennsylvania State University pneumatic total artificial heart (two patients) or with the Pierce-Donachy ventricular-assist pump (six patients). Of the six patients who received the ventricular-assist pump, four received cardiac allografts after 3, 11, 21, and 31 days of pump support, respectively. Two patients died before transplantation; the causes of death were non-device-related complications. One additional patient died of Pseudomonas sepsis after staged cardiac transplantation. The remaining three patients are alive and have been followed up for as long as 2 years after staged cardiac transplantation. Of the two patients who were supported with the total artificial heart, one underwent staged cardiac transplantation after 11 days of support. Unfortunately, this patient succumbed to fungal sepsis 17 days later. The remaining patient, who received the total artificial heart after rejection of a transplanted heart, expired 379 days later before a suitable donor organ could be located. These experiences indicate that 1) the ventricular-assist pump and total artificial heart can provide reasonably safe effective circulatory support until a patient's overall physiological status is optimal, until a donor organ can be located for transplantation, or both; 2) there is a need for short-, intermediate-, and long-term support system capabilities; and 3) regardless of the patients' underlying pathology (ischemic versus nonischemic cardiomyopathy), in most instances, the simpler external ventricular-assist pump is capable of satisfactory hemodynamic circulatory assistance.

Acute Kidney Injury↗
PubMed1987

Aortic valve replacement and combined aortic valve replacement and coronary artery bypass grafting: predicting high risk groups.

To determine which groups of patients are at highest risk for operative or late mortality, 259 consecutive patients who underwent operation between 1978 and 1984 were studied; 170 underwent aortic valve replacement and 89 underwent aortic valve replacement combined with coronary artery bypass grafting. Multivariate analysis of risk factors selected emergency operation and patient age older than 70 years as the strongest predictors for operative death. Although patients having aortic valve replacement and coronary artery bypass grafting had a higher operative mortality rate (13.5 versus 3.5%), the combined operation had no independent predictive effect on early or late results. At a mean follow-up time of 48 months after surgery, 72% of the survivors of operation were living, 10% were lost to follow-up and 18% were dead. Seventy-seven percent of long-term survivors were in New York Heart Association functional class I or II. The incidence of thromboembolism, paravalvular leak, bacterial endocarditis and hemorrhage each occurred at a rate of less than 1% per patient-year. The factors associated with late death were preoperative age, male sex, left ventricular end-diastolic pressure, cardiac index and functional class. Despite an increase in operative mortality, patients undergoing emergency operation were not at higher risk of late death. Operative mortality is concentrated among several high risk groups. For patients undergoing elective operation, operative mortality is low, especially if the patient is less than 70 years old. Late results are good for all groups of patients undergoing operation, including those who are at greater risk of dying at operation.

Adult↗
PubMed1987

Postoperative cardiac support with a pulsatile assist pump: techniques and results.

Since 1980 this group has employed a pulsatile assist pump(s) in 23 patients. Postoperative survival was 39% (9/23). In this group, 16 patients have required left ventricular support; 9 have been weaned from the pump, and 7 have survived (44%). Three patients required right ventricular support, and two have survived (66%). Four patients required biventricular assistance, but none survived. There have been four late deaths in this group. Of the five patients alive and well, all are New York Heart Association Class I or II. Important conclusions include the following: The pulsatile pump can adequately support the pulmonary or systemic circulation for a period of days; dramatic improvement in ventricular function is frequently observed in patients with univentricular failure; adequate right ventricular function is a major determinant of survival in a patient with pulsatile left ventricular support; preoperative cardiogenic shock and/or a prolonged time on cardiopulmonary bypass (CPB) predispose the patient to diffuse intravascular coagulation and a poor result; considerable information remains to be learned regarding the selection of assist pump candidates, optimal CPB techniques, and intraoperative identification of biventricular failure, which will further improve these results.

Adult↗
PubMed1987

An experimental study of Newtonian and non-Newtonian flow dynamics in a ventricular assist device.

The fluid dynamic behavior of a Newtonian water/glycerol solution, a non-Newtonian polymer (separan) solution, and bovine blood were compared in the Penn State Electrical Ventricular Assist Device (EVAD). Pulsed doppler ultrasound velocimetry was used to measure velocities in the near wall region (0.95-2.7 mm) along the perimeter of the pump. Mean velocity, turbulence intensity, local and convective acceleration, and shear rate were calculated from the PDU velocity measurements. Flow visualization provided qualitative information about the general flow patterns in the EVAD. Results indicate that water/glycerol does not accurately model the flow characteristics of bovine blood in the EVAD. The non-Newtonian separan solution produced results closer to those of the bovine blood than did the water/glycerol solution. Near wall velocity magnitudes for the separan were similar to those of the bovine blood, but the profile shapes differed for portions of the pump cycle. All three fluids exhibited periods of stagnation. Bovine blood results indicated the presence of a desired rotational washout pattern at midsystole, while results with the other fluids did not show this feature.

Animals↗
PubMed1987

Long-term results of ventricular assist pumping in postcardiotomy cardiogenic shock.

Short-term survival of patients who require ventricular assist pumping for postcardiotomy cardiogenic shock has been encouraging and has provided enough survivors to allow evaluation of long-term results. We observed nine survivors, 39 to 69 years of age (mean = 54.6) for 10 to 53 months (mean = 31) after their discharge from the hospital. In three patients, the angiographic ejection fraction was normal before the operation, whereas in six patients it was moderately to severely impaired. All nine patients were in New York Heart Association Functional Class IV before operation. After operation, eight of the nine patients were in Functional Class I or II. In the remaining patient, the ejection fraction fell markedly and the postoperative functional class remained unchanged. Two patients were employed full-time and one, part-time. Five patients were retired but active and had no cardiac disability, although two of the five did have residual partial noncardiac disability. The remaining patient, a housewife, continued to have compensated congestive heart failure but was relieved of angina. During the follow-up period, five of the nine patients died suddenly after 12, 18, 25, 30, and 38 months from causes that included pulmonary embolus and probable arrhythmias. Survivors who have had ventricular assist pumping for postcardiotomy cardiogenic shock have a good chance of resuming active lives. The risk of being a "cardiac cripple" is small, as is the risk of significant noncardiac disability.

Adult↗
PubMed1986

Disseminated Trichosporon beigelii (cutaneum) infection in an artificial heart recipient.

A 44-year-old man with end-stage ischemic cardiomyopathy was supported with an intra-aortic balloon and The Penn State Heart (artificial) prior to orthotopic cardiac transplantation on the 14th hospital day. At the time of transplantation, intraoperative cultures of pericardial and mediastinal fluid showed growth of Trichosporon beigelii (cutaneum). Shortly thereafter the patient developed visceral dissemination of T beigelii with no associated skin lesions. He was treated with amphotericin B and rifampin, but postmortem examination showed persistent, disseminated infection.

Adult↗
PubMed1986

Pulsed ultrasonic Doppler velocity measurements inside a left ventricular assist device.

In this study we have employed a single channel, pulsed ultrasonic Doppler velocimeter to measure instantaneous velocity distributions within the pumping chamber of a ventricular assist device. Instantaneous velocities have been decomposed into periodic mean and turbulent fluctuating components from which estimates of Reynolds stresses within the chamber and mean shear stresses along the wall of the chamber have been obtained. A review of the complete data set indicates a maximum value of the mean wall shear stress of 25 dynes/cm2 and a maximum Reynolds stress of 212 dynes/cm2. These values are lower than those measured distal to aortic valve prostheses in vitro and are well below levels known to damage blood components. Core flow patterns, wall washing patterns and flow stagnation points are also revealed.

Assisted Circulation↗
PubMed1986

Left heart and biventricular bypass.

Various forms of circulatory assist devices are currently under investigation. Clinical use of ventricular bypass devices ranging from roller-pump-driven units to pneumatically powered VADs have been in use for several years. These devices are indicated for patients in cardiogenic shock following cardiac surgery or myocardial infarction when all other forms of conventional therapy have failed. Success, though modest, is encouraging in these patients with a dismal prognosis. An increasing role for the VAD may be found in supporting patients whose condition deteriorates while awaiting cardiac transplantation.

Assisted Circulation↗
PubMed1986

Mechanical support of the circulation followed by cardiac transplantation.

Improvements in both mechanical circulatory support devices and immune therapy promise a wider use of sequential mechanical support as a bridge to orthotopic cardiac transplantation. The intra-aortic balloon pump, the left and right ventricular assist pumps, and the pneumatic artificial heart represent the range of devices capable of keeping a patient alive who is awaiting a donor organ. The major difficulty in using circulatory support devices is infection, which is caused by their required percutaneous tubes. We report here our experiences with mechanical circulatory support devices as a bridge to cardiac transplantation. In a series of 31 consecutive transplant procedures, six patients have required preoperative mechanical circulatory support. The intra-aortic balloon pump was used in two patients for 2 and 14 days, respectively, before transplantation. Both patients are well 10 and 11 months after the transplant procedure. Two patients required the left ventricular assist device for 11 and 21 days and are alive 3 weeks and 8 months, respectively, after transplantation. One patient was supported by the pneumatic artificial heart for 10 days before a donor heart became available but died of septic shock 17 days after transplantation. A second patient received a pneumatic artificial heart 7 days after transplantation when the heart transplant failed. He has been in stable condition for 45 days but is recovering from renal failure. Our early experiences indicate that either partial or total mechanical support as a bridge to transplantation is successful if overwhelming sepsis or renal failure can be avoided.

Adult↗