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Biomedical subjects

O H Frazier

Publications and source records attributed to O H Frazier.

At least 379 records · Page 21Linked to original sources
PubMed1978

Sinus venosus atrial septal defect: early and late results following closure in 109 patients.

The clinical course of 109 patients who underwent closure of a sinus venosus atrial septal defect is reviewed, with emphasis on the incidence, type, and severity of arrhythmias before and after operation. There were no operative deaths and only 1 late death. No instances of obstruction of the superior vena cava were detected clinically. One patient had a probable hemorrhagic pulmonary infarction that cleared; another may have a persistent left-to-right shunt. Excellent results were achieved in 72% of the patients, good results in 5%, and poor results in 3%. The type of arrhythmia, both before and after operation, varied with the age of the patient: younger patients had bradyarrhythmias, and older patients had tachyarrhythmias. Ten patients experienced persistent new arrhythmias postoperatively, but none were disabled, required a pacemaker, or died. The arrhythmias in all severely symptomatic patients were supraventricular tachycardias that had occurred before operation. Although functional classification after operation was clearly related to age at the time of the procedure (with younger patients having the best functional results), 19 of 21 patients over age 40 were noticeably improved after surgical closure of the sinus venosus atrial septal defect.

Adolescent↗
PubMed1978

Resection of the aortic arch using deep hypothermia and temporary circulatory arrest.

Resection of the aortic arch has been associated with prohibitive morbidity and mortality because of the technical magnitude of the operation. Six patients, including a 6-year-old boy, recently underwent resection of an aneurysm involving the aortic arch. Deep systemic hypothermia was instituted utilizing cardiopulmonary bypass. Resection of the aneurysm and replacement with a Dacron prosthesis were then performed during a period of total circulatory arrest. During this period the total blood volume of the patient was transferred to the extracorporeal circuit, thus producing a completely dry operating field. Five patients are alive and well although one suffered a transient neurologic deficit from air embolism. The sixth patient died from bleeding. This technique considerably simplifies a difficult operation by producing excellent exposure and eliminating the need for continuous cerebral perfusion. Our experience suggests that resection utilizing deep hypothermia and temporary circulatory arrest is the treatment of choice for patients with aneurysms of the aortic arch.

Adult↗
PubMed1977

The use of pyloric exclusion in the management of severe duodenal injuries.

Repair of severe duodenal injuries often constitutes a technical challenge, and a variety of special technics have been described. For the past seven years we have utilized temporary pyloric exclusion and gastrojejunostomy to produce "diverticulization" of the duodenum. This procedure was utilized in seventy-five patients selected from 175 consecutive patients presenting with duodenal trauma. The mortality was 19 per cent and the rate of fistula formation was 5 per cent in this series and 14 per cent and 2 per cent, respectively, in the overall series. Follow-up studies of gastric physiology and functional anatomy show no evidence of alteration of these parameters. We thus believe that patients presenting with severe duodenal trauma and often multiple devastating associated organ injuries can be adequately treated with this procedure with a significant decrease in mortality and with marked improvement of postoperative morbidity.

Adult↗
PubMed1977

The role of preoperative mesenteric arteriography in colon interposition.

In a series of mesenteric arteriograms, the marginal artery in the right colon was present in six of 20 studies (30 percent); in the left colon it was present in all of the 20 cases studied (100 percent). Such preoperative knowledge of the vascular pattern permits the surgeon to choose a suitable segment of bowel for successful colon interposition and assists him in shortening the operative time. When this information was applied in 19 consecutive left colon interpositions, only one major suture line dehiscence in the neck was encountered (5.3 percent).

Colon↗
PubMedDate not supplied

Histologic findings proving the existence of humoral rejection in a cardiac allograft.

Humoral rejection (HR) of the cardiac allograft is neither well characterized nor universally recognized in the transplant/pathology-related literature. One reason for this is that the histologic light-microscopic features are inconsistent, making HR difficult to recognize in the majority of cases. We report an unusual case of cardiac allograft rejection in a patient with a complicated postoperative course who ultimately died within 6 months of transplant. Premortem, HR was not diagnosed in multiple cardiac biopsies. The autopsy revealed unequivocal histologic and immunohistochemical evidence of HR. Vascular distension and endocardial infiltration by numerous macrophages were noted only in the cardiac allograft and were notably absent in the native tissue present within the anastomotic sites. There was capillary deposition of immunoglobulin and complement shown by immunofluorescence staining of frozen tissue, and there was diffuse immunohistochemical staining for C4d within the intramyocardial vessels. This case appears to represent an exaggerated antibody-mediated rejection of the cardiac allograft.

Adult↗
PubMedDate not supplied

Left atrial metastasis from hepatocellular carcinoma: a case report.

This is the second reported case of a patient with hepatocellular carcinoma in whom the presence of a solitary, left atrial metastatic tumor was confirmed with the aid of transesophageal echocardiography. The tumor was discovered during computed tomography scanning at a follow-up examination after a 3-month regimen of chemotherapy. The patient had exhibited no signs of cardiac involvement, which may have been the result of the relatively small size of the tumor. Surgical excision of the tumor was successfully undertaken, and the patient's postoperative course was uneventful. In this case, transesophageal echocardiography was valuable in providing information regarding the exact location of the tumor and its relation to surrounding anatomical structures.

Carcinoma, Hepatocellular↗
PubMedDate not supplied

Mechanical circulatory support for perioperative donor heart failure.

Perioperative acute donor heart failure can be caused by various factors, such as recipient pulmonary hypertension, marginal donor heart function, or immunologic mismatch. Of 265 patients who underwent orthotopic transplantation, four received mechanical support for acute perioperative donor heart failure. In two patients with reactive pulmonary hypertension, right heart bypass (RHB) with a centrifugal pump was used for 53 and 36 hr, respectively. One patient who experienced biventricular donor heart failure was supported for three days with an intraarterial, transvalvular, axial-flow left ventricular assist device (LVAD). Circulation was supported effectively with the LVAD, despite an initial absence of right ventricular function. The fourth patient, who had signs of heart failure, received intraaortic balloon pump support for 24 hr after transplantation. All four patients were weaned from circulatory support, and heart function was restored in each; the mean left ventricular ejection fraction was 63% (range from 57 to 71%). One patient died of fungal infection 14 days after being weaned from pump support, another died of lymphoma two months after support was discontinued, and the remaining two patients are well 9 and 18 months after transplantation. In cases of acute donor heart dysfunction, temporary mechanical assistance is a reliable option for supporting the circulation during heart recovery.

Adult↗
PubMedDate not supplied

Clinical experience with the Hemopump.

Complications associated with surgical procedures generally required for implantation of left ventricular assist devices (LVADs) may limit them from providing adequate circulatory support for patients suffering from profound left ventricular failure (LVF). Such problems are minimized with the use of the Hemopump, a recently developed intraarterial LVAD. This 7 mm transvalvular axial flow blood pump is percutaneously powered by an external console with a flexible drive cable. Since April 1988, we have used the device effectively in 12 patients. Indications for device application included postcardiotomy shock in eight patients, acute allograft rejection in two, severe allograft failure in one, and acute myocardial infarction in one. The Hemopump was inserted from the femoral approach in eight patients, the ascending aorta in three, and the abdominal aorta in one. During the first 12 hr of support, cardiac index (CI) ranged from 1.14-2.98 L/min/m2, and pump flow was 3.0 to 3.6 L/min. As the patients' hearts recovered, the pump speed was gradually reduced. Circulatory support ranged from 26 to 139 hr; 10 of 12 patients were successfully weaned. The mean CI before device removal was 2.74 +/- 0.4 L/min/m2, and the pump flow was 2.14 +/- 0.69 L/min. No device-related infections or thromboembolic episodes occurred. Plasma-free hemoglobin remained within acceptable levels during pumping. Six patients survived more than 30 days after pump removal. Thus, the Hemopump can provide safe, stable, temporary circulatory support and can be expeditiously applied with minimal complications.

Adult↗
PubMedDate not supplied

Extended clinical support with an implantable left ventricular assist device.

Clinical evaluations are under way of an intracorporeal (abdominally positioned) pulsatile left ventricular assist device (LVAD) that is capable of providing support for extended periods (greater than 30 days) in patients awaiting heart transplantation. The LVAD, developed by Thermo Cardiosystems Inc. (Woburn, MA), has uniquely textured blood contacting surfaces and requires only minimal antithrombotic therapy. It has been used at the Texas Heart Institute as a bridge to transplantation in 11 patients, including 2 who are currently receiving support. Four patients required extended LVAD support (35-132 days); of those, three are doing well at 1.5, 8.5, and 13 months, respectively, after transplantation, and one died of liver failure 49 days after transplantation. The LVAD was operated in a fixed-rate mode to maintain pump flows at 4-8 L/min, resulting in stabilization of hemodynamic and secondary organ function in all patients. Blood chemistry and hematologic values returned to normal during LVAD support in three of four patients. Postoperative anticoagulation was gradually reduced over the course of the trials. The two most recent patients (35 and 132 days) received only oral dipyridamole (75 mg X 3/day) and aspirin (80 mg/day) after the early recovery period (four-six days), resulting in normal prothrombin and partial thromboplastin times. Plasma hemoglobin levels remained within acceptable limits, and there was no evidence of thromboembolism. Blood contacting surfaces were coated with a thin, adherent, biologically derived lining. The initial results indicate that the intracorporeal LVAD, with textured blood contacting surfaces, can effectively support the failing heart for extended periods (greater than 30 days) with minimal antithrombotic therapy.

Adult↗
PubMedDate not supplied

Anatomic considerations for abdominally placed permanent left ventricular assist devices.

To determine anatomic parameters for a permanent, electrically actuated left ventricular assist device (LVAD), the effects of abdominal placement of pneumatic LVADs used as temporary support for patients awaiting heart transplantation was studied. Understanding the anatomic constraints imposed by the abdominal viscera in LVAD placement is crucial, because improper placement can result in compression or obstruction of adjacent structures. Anatomic compatibility was assessed in four men (age 22-48 years) who were supported by the LVAD for over 1 month (range 35-132 days). The pump was intraperitoneally placed in the left upper quadrant. Radiographic techniques were employed, including CT scanning (with patients supine) and contrast imaging (patients in anatomical position), and the pump and conduits appeared to be properly positioned, with minimal compression of the body of the stomach, and no obstruction of adjacent organs. Three patients returned to a solid food diet and exercised daily by stationary cycling and walking. No signs of migration or erosion of the pump were present at the time of LVAD removal and cardiac transplantation. Successful clinical experience with short-term use of the LVAD suggests that the electrically actuated device can be well tolerated in patients requiring permanent left ventricular assistance.

Abdomen↗
PubMedDate not supplied

The effect of prolonged left ventricular support on myocardial histopathology in patients with end-stage cardiomyopathy.

To determine the histopathologic effect of prolonged (> 30 days) left ventricular unloading on the myocardium, the authors studied myocardial tissue specimens from eight men (mean age, 40.8 years) with end-stage cardiomyopathy (six idiopathic, two ischemic) who were supported with the HeartMate (Thermo Cardiosystems, Inc., Woburn, MA) left ventricular assist device (LVAD) as a bridge to cardiac transplantation. The average length of support was 79.6 days (range, 31-136 days). Before left ventricular support was instituted, transthoracic echocardiography revealed that all patients had significantly dilated left ventricular cavities (average left ventricular diastolic dimension, 7.2 cm). Tissue specimens from the core of the left ventricular apex, which is removed at the time of LVAD implantation, were compared through pathologic examination with specimens from the explanted hearts at the time of cardiac transplantation. Apical core specimens from all patients exhibited extensive areas of attenuated myocardial fibers, combined with wavy patterns in some areas. In these regions, the nuclei of the cardiac myocytes from idiopathic cardiomyopathy specimens were neither pyknotic nor disappearing, as was noted in an infarcted area of a specimen from one patient with ischemic cardiomyopathy. At the time of heart transplantation, myocardial tissue specimens from the explanted hearts had a significant decrease or disappearance of stretched fibers. There was also a slight increase in interstitial replacement fibrosis, as well as an increase in the diameter of the myocardial fibers. These findings appear to correlate with the clinical impression of improved native ventricular function and with radiographic findings and decreased chamber size during prolonged ventricular support.

Adult↗
PubMedDate not supplied

Human intraperitoneal response to a left ventricular assist device with a Ti-6AI-4V alloy surface.

The soft tissue reaction to long-term implantation of an intraperitoneal left ventricular assist device (LVAD) was investigated. The HeartMate 1000 (Thermo Cardiosystems, Inc., Woburn, MA) is a pneumatically driven blood pump with smooth titanium alloy (Ti-6AI-4V) outer surfaces that is placed intraperitoneally in the left upper quadrant and sutured to the anterior abdominal wall. It is being used currently as a bridge to cardiac transplant, which sometimes requires extended support times. We examined the tissue capsule that formed around the rigid circular pump housing of four LVADs (duration of implant: 61, 86, 128, and 153 days) for gross, histologic, immunohistochemical, and ultrastructural analysis. Immunostaining was performed using monoclonal and polyclonal antibodies against cytoskeletal tissue markers (vimentin, desmin, alpha-smooth muscle actin), T and B lymphocytes, carcinoembryonic antigen, factor VIII, and cytokeratins (CAM 5.2 AE1/AE3, 34 beta E12, and 35 beta H11). Direct fluorescent immunolabeling for fibrinogen was also performed to characterize cell and tissue type. Histologic analysis of the 3 to 4 mm thick capsule with white, glistening inner surfaces showed fibrovascular tissue with multipotential subserosal cells (MSCs), capillary endothelium, collagen, and a few mononuclear infiltrates. The immunohistochemical profile of the MSCs differed from myofibroblasts despite a morphologic similarity. Transmission electron microscopy revealed abundant rough endoplasmic reticulum and peripherally arranged myofilaments within the spindle shaped cells. It was hypothesized that capsule formation was initiated by fibrin deposition, followed by proliferation of MSCs and subsequent formation of fibrovascular tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Clinical responses to ventricular assistance versus transplantation in a series of bridge to transplant patients.

Hemodynamic and peripheral organ responses to ventricular assistance were compared with transplantation in a cohort of patients bridged with the HeartMate 1000 IP left ventricular assist device (LVAD) (Thermo Cardiosystems Inc., Woburn, MA). The study population included 27 patients that were supported an average of 102 days (range, 15-324 days). Two hepatic (total bilirubin and serum glutamic oxaloacetic transaminase [SGOT]) and two renal (creatinine and blood urea nitrogen [BUN]) parameters were measured: 1) before LVAD insertion, 2) 30 and 60 days during ventricular assistance, 3) before transplantation while still on the VAD, and 4) 30 and 60 days after transplantation. Total bilirubin values were significantly greater just before LVAD implant (2.3 mg/dl) than before transplantation (0.7 mg/dl). Although there was no difference after 30 days of either treatment, the total bilirubin values were greater at 60 days after transplantation (1.1 mg/dl) than at an equivalent time on the LVAD (0.6 mg/dl). The SGOT values were also significantly reduced before transplantation. No differences at 30 and 60 days after either procedure were noticed. Creatinine and BUN values were greater before LVAD implant (1.7 and 37 mg/dl) than before transplantation (1.2 and 19 mg/dl). The creatinine values were also greater after transplantation at 30 and 60 days (2.0 and 1.6 mg/dl) than at comparable intervals after LVAD implantation (1.0 and 1.2 mg/dl), presumably as a result of the use of immunosuppressive drugs. End organ function was markedly improved while on the device, enhancing the physiologic status of the patients before transplantation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Use of a left ventricular assist device in an outpatient setting.

The vented electric Heartmate LVAD (VE-LVAD) (Thermo Cardiosystems, Inc., Woburn, MA) is a reliable, fully portable system that allows selected patients with end-stage cardiomyopathy to undergo outpatient treatment while waiting for heart transplantation. This implantable, pusher-plate LVAD is actuated by an electric motor located within the pump housing. The patient wears external batteries and a system controller, which power and control the LVAD motor through a percutaneous lead. Since May 1991, four men have been supported with the VE-LVAD. They ranged in age from 33 to 50 years (mean, 44.3 years); two had idiopathic cardiomyopathy, and two had ischemic cardiomyopathy. Of the four patients, three underwent support of 196, 219, and 504 days; support in the fourth patient is ongoing at more than 90 days. All four patients were fully rehabilitated to New York Heart Association Class I status. Because they were well and fully mobile, the protocol was amended to allow these patients to leave the hospital in a four phase program that begins with 16 hr day passes and leads to hospital discharge. When patients leave the hospital, they are accompanied by trained family members or friends. The patients who have participated in the program have performed routine activities, attended social events, and spent the night at home. The VE-LVAD system seems safe and appropriate for the outpatient setting in selected patients. Patients have been able to manage the system without assistance from medical or engineering personnel. This initial positive experience with outpatient LVAD treatment demonstrates the potential for providing long-term cardiac support with this type of implantable technology.

Activities of Daily Living↗
PubMedDate not supplied

Chronic in vivo evaluation of an electrohydraulic total artificial heart.

Development of the Abiomed total artificial heart (TAH) designed for human use is progressing. Implant durations of longer than 60 days have been achieved in calves. The device consists of blood pumps, valves, and a hydraulic atrial flow balancing chamber fabricated from polyetherurethane. The energy converter, a centrifugal hydraulic pump with a rotary fluid switching valve, is positioned between the blood pumps. In two consecutive chronic in vivo studies (47 days and longer than 60 days), cardiac output was maintained in excess of 8 l/min. The atrial flow balancing chamber maintained a mean right-to-left pressure gradient of 7.5 and -1.4 mmHg in each respective study. There were no pulmonary complications. Platelet counts, fibrinogen concentrations, and hematocrit values returned to baseline levels within 20 days, whereas bilirubin, serum glutamic-oxaloacetic transaminase, blood urea nitrogen, and creatinine levels returned to normal within 1 week of implant. After the first post-operative day, plasma free hemoglobin levels of less than 10 mg/dl indicated no device-related hemolysis throughout the duration of the studies. At explant (47 day study), pathologic analysis showed no renal infarcts, no tissue necrosis, and no thermal damage. The device was fully encapsulated by 2-4 mm thick fibrous connective tissue. A newly designed textured-to-smooth surface inflow showed no signs of pannus ingrowth or thrombotic complications. These studies demonstrate that this TAH is suitable for long-term implantation.

Animals↗
PubMedDate not supplied

In vivo evaluation of a trileaflet mechanical heart valve.

Design goals for a mechanical heart valve include duplicating the hemodynamic performance of the natural valve, eliminating the need for anticoagulants, and maintaining safety. The Lapeyre-Dassault (Dassault-Aviation, Paris, France) prosthetic valve, undergoing development, addresses these goals. The unique trileaflet design consists of a solid titanium ring and three leaflets. Prototypes of the valve fabricated with Delrin leaflets were implanted in the mitral position in six calves (70-90 kg). Four calves (Studies 1, 2, 3, 5) had long-term survival of 165, 158, 219, and 281 days, respectively. Two calves were killed, one on Day 37 and one on Day 39, after complications unrelated to the valve developed. In all calves heparin was given intravenously to maintain partial thromboplastin time at 1.5 to 2.0 x baseline for approximately 1 week. In Studies 1 and 2 full anticoagulation and antiplatelet therapy was given (orally administered sodium warfarin to maintain prothrombin time at 1.5 to 2.0 x baseline, along with aspirin (1 g/day) and dipyridamole 400 mg/day). In Study 3, all anticoagulation and antiplatelet therapy was discontinued at 1 month after implant. In Study 5, no anticoagulation therapy was given after the initial week of intravenous heparin; however, antiplatelet therapy was started on the fifth postoperative month and maintained until the study's end at 9 months. At 1, 2, 3, and 5 months, the mean plasma free hemoglobin level in the four long-term animals was 5.0 +/- 2.16, 6.0 +/- 3.83, 8.5 +/- 4.93, and 11.3 +/- 6.74 mg/dl, respectively. Hemolysis was not a problem. Valve performance during normal activity was excellent in all the calves, as evidenced by echocardiography and the overall appearance of good health. In the four completed long-term studies, left heart catheterization showed a mean valve pressure gradient of 11.57 +/- 1.26 mmHg and no apparent valvular regurgitation. Histopathologic examination of major organs showed no evidence of thromboembolic events. This study shows that the innovative design of this trileaflet valve performed well in initial in vivo testing, justifying further development.

Animals↗
PubMedDate not supplied

In vivo evaluation of an intraventricular electric axial flow pump for left ventricular assistance.

In vivo studies have begun to evaluate a new intraventricular electric axial flow left ventricular assist device (LVAD), the Jarvik 2000, which is a small, valveless pump that is placed inside the left ventricle through the left ventricular apex. The operation, which is performed through a left thoracotomy, may be done without cardiopulmonary bypass and aortic cross-clamping. Outflow is provided through a 16 mm softly woven, Dacron graft anastomosed to the descending thoracic or abdominal aorta. Pump flow, which varies from 2 to 16 l/min in vitro, is changed by adjusting the speed of pump rotation. Preliminary studies were done to evaluate the ease of implantation, hematologic and anatomic compatibility, and pump performance. The device has been implanted in seven healthy, preconditioned calves (83-138 kg), one of which is currently undergoing support. The implantation procedure averaged 3 hours. There were no operative deaths, and blood transfusions were not required. Postoperatively, anticoagulation was achieved with heparin followed by warfarin sodium to maintain prothrombin time or partial thromboplastin time at 1.5-2.0 times baseline. In the six completed studies, support time ranged from 2 to 120 days (mean, 36 days). The seventh calf has been supported for 30 days. In the four long-term studies (20, 70, 120, > 30 days), the mean plasma free hemoglobin values during support were 11.0, 7.7, 6.6, and 3.4 mg/dl, respectively. Under normal conditions, the average daily flow rate ranged from 5 to 6 l/min. During treadmill exercise (10% grade, 1.5 km/h) lasting 20 minutes, peak flow rates exceeded 8 l/min. These pilot studies suggest that this intraventricular axial flow pump is relatively easy to implant, operate, and control. In addition, it is hemocompatible, provides physiologic flow rates, and may be able to provide long-term circulatory support.

Animals↗