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Biomedical subjects

M E DeBakey

Publications and source records attributed to M E DeBakey.

At least 37 records · Page 2Linked to original sources
PubMed1998

Use of the Internet for long-term clinical follow-up.

Use of the Internet for patient-specific consultation across international boundaries has been demonstrated. This report describes the efforts of Baylor College of Medicine and NASA to conduct a telemedicine consultation with Moscow, Russia. Consultation between Russian and American physicians was performed over the Internet with a combination of real-time and store-and-forward techniques. The clinical focus involved a 65-year old Russian scientist who had undergone mitral valve replacement in the United States 5 years earlier. Development of new activity-related chest pain, dyspnea, and intermittent atrial fibrillation led to a consultation with his American cardiologist and cardiac surgeon. Real-time video was supplemented with telephone voice communication to overcome bandwidth limitations. Prior to the video link, the patient's recent history and clinical data were made available via the Internet using file transfer protocol (FTP). The patient's medications, new electrocardiographic findings, and activity status were reviewed. Specific clinical recommendations were made as a result of this telemedicine consultation. This case illustrates the technical factors, clinical implications, and confidentiality issues related to using the Internet for telemedicine consultations and demonstrates that the Internet may provide an alternative means for long-term clinical follow-up of patients.

Aged↗
PubMed1997

Animal rights.

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Animal Rights↗
PubMed1997

Improved flow straighteners reduce thrombus in the NASA/DeBakey axial flow ventricular assist device.

A small axial flow ventricular assist device (VAD) measuring 3 inches long and 1 inch in diameter is in development. The pump consists of a spinning inducer/ impeller, a flow straightener (FLS), and a diffuser enclosed in a cylindrical flow tube. The impeller has rod-shaped permanent magnets embedded within its 6 blades and is activated magnetically by the motor stator which is positioned outside the flow tube. At the completion of a previous study, the FLS was identified as a thrombogenic area. The aim of the present study was to evaluate the thrombogenicity of redesigned FLSs (swept-back and bulbous types), compared with standard type (STD) FLS. A total of 15 pumps (STD, n = 7; swept-back, n = 4; and bulbous, n = 4) were sequentially implanted into 4 calves paracorporeally in a short-term ex vivo test. The STD and bulbous FLSs experienced thrombus formation, but the swept-back FLS was thrombus free during a 48 h screening test.

Analysis of Variance↗
PubMed1997

Cytomegalovirus infection and atherosclerosis.

The biological properties of human cytomegalovirus are consistent with pathogenic involvement at several levels of the atherogenic process. Although the sites of latency of CMV have not been established, both smooth muscle cells and leukocytes are likely possibilities. The observations of viral antigens and nucleic acid sequences in arterial smooth muscle cells suggest that latent CMV infection of the arterial wall may be common in patients with atherosclerosis. The seroepidemiologic studies suggest that a periodically activated latent infection is present in patients with atherosclerosis. Important are the observations that in immunosuppressed heart transplant patients infected with CMV, atherosclerosis is prone to develop in the transplanted heart. This mainly circumstantial evidence of the involvement of CMV in human atherosclerosis provides an important basis for further investigation of the role of CMV in atherogenesis.

Animals↗
PubMed1996

Aortocoronary bypass with saphenous vein graft. Seven-year follow-up. 1973.

A 42-year-old man had extensive occlusive disease of the coronary artery and angina pectoris. An autogenous saphenous vein bypass from the ascending aorta to the anterior descending coronary artery was performed on Nov 23, 1964. The patient suffered an asymptomatic anterior myocardial infarction during operation but made an uncomplicated recovery. Seven years after the operation, the graft functions with normal left ventricular hemodynamics, while the occlusive process has produced obstruction of the left main coronary artery and almost complete occlusion of the right coronary artery. To our knowledge, this is the first successful case of a saphenous vein-coronary artery bypass with the longest follow-up of a functioning coronary vein bypass graft.

Coronary Artery Bypass↗
PubMed1996

Ex vivo phase 1 evaluation of the DeBakey/NASA axial flow ventricular assist device.

A small ventricular assist device intended for long-term implantation has been developed by a cooperative effort between the Baylor College of Medicine and the NASA/Johnson Space Center. To date, in vitro tests have been performed to address hemolysis and pump performance issues. In this Phase 1 study, we assessed the durability and atraumatic features aiming for 2 day implantation. Eight pumps were implanted in 2 calves as paracorporeal left ventricular assist devices. The pump running times ranged from 18 to 203 h (78.1 +/- 23.7; mean +/- SEM). All the pump implantations were terminated because of thrombus formation. Plasma-free hemoglobin levels were below 13.7 mg/dl, except for 1 case complicated by inflow cannula obstruction. The pump speed was maintained between 10,100 and 11,400 rpm. Pump outputs were from 3.6 to 5.2 L/min. The electrical power required by the system ranged between 9 and 12 W. Clinically there was no detectable organ dysfunction noted, and postmortem evaluation demonstrated no pump related adverse effects in either calf except for small kidney infarctions. Thrombus deposition was observed mainly at the hub portions and the flow straightener.

Alanine Transaminase↗
PubMed1996

History, the torch that illuminates: lessons from military medicine.

As in civilian medical practice, only by recording and analyzing military medical experiences can we apply the lessons of the past to future medical practice and improve the care of military personnel. Had certain problems in World War I been recognized and addressed, their repetition in World War II could have been avoided. The end of hostilities brings such a sense of relief that we are inclined to want to put the experience behind us. But we must remain prepared for any natural emergency, and one way to do that is to study the past and incorporate its lessons in future actions.

History, 20th Century↗
PubMed1996

Cytomegalovirus and atherosclerosis.

The investigations reviewed in this paper provide evidence that a member of the herpesvirus family can cause atherosclerosis in chickens. In vitro experiments, as well as studies of arteries from infected birds, suggest that a virus-induced alteration of cellular metabolism, which results in the accumulation of cholesterol and cholesteryl esters, may be the primary mechanism in development of viral atherosclerosis. In addition, the fact that the same avian virus induces a malignant lymphoma suggests that it may also have the potential to stimulate the proliferation of other cells, notably arterial smooth muscle cells. The evidence for involvement of one or more members of the herpesvirus family in human atherosclerosis is much more circumstantial. Cytomegalovirus (CMV) is prevalent, increasing with age, so that a majority of the human population becomes infected by adulthood. As with other herpesviruses, the infection with CMV is usually subclinical or latent. Although the sites of latency for CMV have not been established, both smooth muscle and leukocytes are likely possibilities. The observations of viral antigens and nucleic sequences, but not infectious virus, in arterial smooth muscle cells suggests that latent CMV infection of the arterial wall may be common in patients with atherosclerosis.

Adolescent↗
PubMed1995

Cytomegalovirus and atherosclerosis.

Finding that an avian herpesvirus can cause atherosclerosis in chickens prompted studies of human herpesviruses in human atherosclerosis. Antigens and nucleic acid sequences of cytomegalovirus (CMV), a widespread member of the herpesvirus family, were found in arterial lesions in human atherosclerosis, but infectious virus has not been observed. In atherosclerosis patients, high levels of CMV antibodies are present, suggesting the presence of virus that had been activated from a latent state. Atherosclerosis also develops in immune-suppressed heart transplant patients infected with CMV. The properties of CMV are consistent with its involvement at several levels of the atherogenic process. If this concept is correct, immunization with a CMV vaccine should prevent CMV infection and atherosclerosis.

Arteriosclerosis↗
PubMed1995

A fluid dynamic analysis using flow visualization of the Baylor/NASA implantable axial flow blood pump for design improvement.

The Baylor/NASA Axial Blood Flow Pump has been developed for use as an implantable left ventricular assist device (LVAD). The pump is intended as an assist device for either pulmonary or systemic circulatory support for more than 3-months' duration. To date the pump provides acceptable results in terms of thrombus formation and hemolysis (IH of 0.018 g/100 L). A fluid dynamics analysis using flow visualization was performed to investigate the flow fields and to determine areas within the pump that could be improved. These studies focused upon the inflow area in front of the pump. A prototype axial flow pump assembly was constructed to facilitate the flow visualization studies. Particle image tracking velocimetry techniques were used to measure Amberlite particles suspended in a blood analog fluid composed of 63% water and 37% glycerin. This method used a pulsed (612 Hz) laser light to determine flow velocity profiles, shear stress, Reynolds numbers, and stagnant areas within the axial pump. These studies showed that the flow straightener (a vaned assembly in the pump inflow) reduced Reynolds numbers from 4,640 to 2,540 (at 8.5 L/min) and that the flow straightener exacerbates a discontinuity found between it and the impeller. Within the inflow area, a maximum of 80 N/m2 shear stress was measured, which is well below published blood damage thresholds. Design variations were investigated resulting in a smoother flow transition between flow straightener and impeller. These variations must be investigated further to establish a correlation with hemolysis and thrombus formation.

Blood Flow Velocity↗
PubMed1994

Health care costs.

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Academic Medical Centers↗
PubMed1994

Cytomegalovirus DNA in arterial walls of patients with atherosclerosis.

The biological properties of cytomegalovirus (CMV) are consistent with a potential role in the pathogenesis of atherosclerosis. The evidence of such a role has so far been circumstantial, but CMV nucleic acid is beginning to be reported with increasing frequency in the arterial wall. Arterial specimens from 135 patients who underwent vascular surgery for symptomatic atherosclerotic vessel disease were analyzed by PCR for the presence of CMV nucleic acid. Samples were studied from the atheromatous plaque area and from uninvolved aortic tissues of patients undergoing surgery for vascular disease. One primer pair (LA) was used for detection of a late gene, and two other primer pairs (E1 and E2) were used for the immediate early gene region. Serum antibody to CMV was measured by radioimmunoassay. With the late gene primer, CMV nucleic acid was found in 76% of the tissue specimens tested, whereas the E2 gene primer complementary to the transforming mtr2 region was reactive in 90% of the arterial samples. There was no significant difference in the prevalence of CMV DNA in atherosclerotic plaque tissue and in uninvolved aortic tissue from the patients. A second early gene primer was not reactive with the tissue specimens, although it gave positive results with the positive control of infectious virus. Serum antibody to CMV was detected in 86% of the patients in whose tissue CMV DNA was demonstrated. CMV DNA was detected in a high proportion of atherosclerotic plaque tissues as well as in uninvolved aortic tissue of surgical patients, suggesting that latent CMV infection of the arterial wall may be a common occurrence in patients with atherosclerosis.

Adult↗
PubMed1994

Cardiopulmonary bypass with Nikkiso and BioMedicus centrifugal pumps.

In our department, a new compact and atraumatic centrifugal pump, Nikkiso, was developed as a second-generation cardiopulmonary bypass pump. To assess and confirm the function and controllability of this pump, comparative studies of cardiopulmonary bypass with Nikkiso and BioMedicus centrifugal pumps were performed using calves. Both pumps provided pump flows of 60-70 ml/kg/min without incidence. The hemodynamics of both groups were stable and within the normal range, and no leakage or thrombus formations were observed in either pump. All hematology and biochemistry data showed no significant differences between the two groups. Plasma free hemoglobin values of the Nikkiso pump tended to be lower than those of the BioMedicus pump. The Nikkiso pump was easy to handle because of its smaller size, and air removal was easily performed because of its low priming volume. The Nikkiso pump demonstrated easy manipulation and good controllability. This compact, atraumatic centrifugal pump meets the requirements for a second-generation cardiopulmonary bypass pump.

Animals↗