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Biomedical subjects

E C Harrison

Publications and source records attributed to E C Harrison.

At least 37 records · Page 2Linked to original sources
PubMed1980

Thrombosis of Björk-Shiley aortic valve prostheses.

Though thromboembolic complications are reportedly minimal in patients with Björk-Shiley aortic valve prostheses, massive thrombosis remains a major and often fatal problem. The authors observed massive thrombosis in 3 patients, only one of whom survived. In all three instances, the disk of the prosthesis was relatively radiolucent. With valves manufactured after late 1975, which contain a tantalum foil hoop, cineradiography is the most rapid and accurate method of showing the disk. A simple method of calculating the valve opening angle from the cineradiograph is described. It is suggested that serial cineradiographs might be useful in detecting lesser degrees of thrombosis and partial immobilization of the disk.

Aortic Valve↗
PubMed1980

Clinical experience with the Kay-Shiley mitral valve prosthesis: an eleven-year follow-up study.

A total of 63 patients, who survived mitral valve replacement with the Kay--Shiley caged disc mitral valve prosthesis, were followed for 11 years by single clinic group to assess long-term results post valve replacement. Sixty-one patients (97%) received a muscle guard type Kay--Shiley prosthesis. All patients received oral anticoagulation therapy. The valvular damage was caused by rheumatic disease in 51 patients, infectious endocarditis in six patients, myxomatous degeneration in two patients, coronary artery disease in two patients, and idiopathic ruptured chordae tendineae in two patients. Late death occurred in 21 patients (33%); the 10-year actuarial survival was 65%. Twenty-six patients had at least one thromboembolic event, and the total number of thromboembolic events was 10.3 per 1000 patient months. Two patients developed prosthetic valve endocarditis. Both patients were heroin addicts and died of valve ring abscess. Long-term periods of clinical observation are necessary to assess the effects and benefits of prosthetic valve implantation. These data are important for comparison with other "10-years" valves.

Adult↗
PubMed1980

The Björk-Shiley aortic prosthesis: Flow characteristics of the present model vs. the convexo-concave model.

Thrombus formation on the aortic face of the disc and tissue overgrowth along the sewing ring adjacent to minor outflow region are major clinical pathologic findings observed with the present model Björk-Shiley aortic prosthesis. These pathologic findings may be attributed to the stagnation zone observed near the aortic face of the disc, and the low flow and shear in the minor outflow region of the prosthesis. In hope of reducing these pathologic conditions the new convexo-concave Björk-Shiley prosthesis was developed. In vitro velocity measurements made with a laser-Doppler anemometer in the immediate downstream vicinity of the convexo-concave Björk-Shiley aortic valve indicate that the design changes have decreased the size of the stagnation zone and have increased flow and shear in the minor outflow region. We conclude that the problems of thrombus formation and tissue overgrowth may be reduced in the new convexo-concave Björk-Shiley aortic valve.

Aortic Valve↗
PubMed1978

Cholelithiasis: a frequent complication of artificial heart valve replacement.

The results of this investigation reveal that 39 per cent of patients in a study group of 46 patients with heart valve prostheses had gallstones if they survived 18 months or longer following valve replacement. In contrast, the prevalence of gallstones in a general population of autopsied rheumatic heart disease patients, including those who had been operated for severe valvular heart disease and had not survived for more than one month, was only 12 per cent. These findings suggest that gallstones are a frequent late complication of heart valve replacement.

Adult↗
PubMed1978

Thromboembolism in mitral porcine valve recipients.

A low incidence rate of thromboembolism has been reported in mitral porcine valve recipients. In contrast, 5 of 22 single mitral porcine valve recipients (23 percent) followed up in our clinic for a mean of 16 months had thromboembolic events. All patients but one were receiving long-term anticoagulant therapy. One thromboembolic event resulted in death, three in permanent neurologic deficits and one in a peripheral arterial occlusion. All five patients with emboli had atrial fibrillation and left atrial enlargement. Three had thromboembolic events before porcine heart valve implantation. In addition, five mitral porcine valve recipients who were not receiving anticoagulant therapy were examined at autopsy. Thrombus was identified in the left atrium in three patients, at the tissue-valve interface (sewing ring) in two, on the porcine valve cusps in one and in the right atrium in one. Factors influencing thrombus formation such as left atrial enlargement, atrial fibrillation and a prosthetic device are present after mitral porcine valve implantation and are indications for long-term anticoagulation therapy.

Adult↗
PubMed1978

The Björk-Shiley aortic prosthesis: flow characteristics, thrombus formation and tissue overgrowth.

Thrombus formation and tissue overgrowth were observed in nine Björk-Shiley aortic prostheses recovered six months or longer after implantation. These pathologic findings may be attributed to the flow characteristics of the prosthesis. The open disc of the valve separates the flow into two unequal regions. Varying degrees of thrombus formation were observed in the minor outflow region, including the depression in the aortic face of the disc and the metal strut bridging this area. Tissue overgrowth was noted along the perimeter of the prosthesis adjacent to the minor outflow region. That overgrowth further reduced the available cross section for flow in this already constrained area. In vitro velocity measurements with a laser-Doppler anemometer identified a zone of stagnation about 20 mm wide near the aortic face of the disc. The average velocities in the major and minor outflow regions were around 100 and 25 cm/sec, respectively, and the corresponding peak-shear stresses were approximately 700 and 150 dynes/cm2. There is reason, then, to attribute the thrombus formation and tissue overgrowth to the stagnation zone and the low shear in the minor outflow region.

Aortic Valve↗
PubMed1977

Clinical experience with the Smeloff-Cutter aortic valve prosthesis: an 8-year follow-up study.

A total of 46 patients who survived aortic valve replacement with the present model Smeloff-Cutter prosthesis between 1968 and 1973 were followed up postoperatively. All patients received oral anticoagulant therapy. The average age at implantation was 44 +/- 13 (mean +/- standard deviation) years; 36 patients were male and 10 were female. The valve damage was caused by rheumatic disease in 19 (41 percent), infective endocarditis in 14 (30 percent), congenital heart disease in 7 (15 percent) and other factors in 6 (13 percent). Late death occurred in eight patients (17 percent). All available patients were followed up until December 1976. During the 8 years of follow-up study, seven patients, including four heroin addicts, had postoperative endocarditis (15 percent); five of the seven had cerebral involvement, possibly from septic emboli. Four patients were reoperated on; three had active endocarditis and one had a high transvalve pressure gradient. The mean follow-up time was 4.9 years per patient. Of the 38 living patients, 33 have functional improvement and are still being followed up. Only one patient had a bland embolism to a systemic artery. No ball variance or other types of material failure have been detected. Although the chronic aspects of valve disease remain after prosthetic valve replacement, the Smeloff-Cutter aortic prosthesis deserves strong consideration when selecting a rigid prosthesis for aortic valve replacement.

Adult↗
PubMed1977

The role of serial echocardiography in the evaluation and differential diagnosis of pericardial disease.

Echocardiography is an established method for the diagnosis of pericardial effusion. Echographic findings in fibroadhesive disease have also been described. The interpretation of a changing serial echogram during the clinical course of pericardial disease has not been established. Sixteen patients with echographic evidence of pericardial effusion were followed with serial echographic studies. In seven, surgical or autopsy correlation was obtained. Because of the serial changes noted we undertook a study in dogs to clarify the problem of variability in intensity of sound reflected from the pericardial space. Three open-chested dogs were studied with rapid sequence surface echograms as blood introduced into the pericardial space was converted from the unclotted to the clotted state. In all three dogs blood clooting increased the intensity or sound reflected from the pericardial space. Our study of two patients with fibroadhesive pericardial disease documents serial changes in echoes from the pericardium and pericardial space accompanying the clinical evolution of the disease process, and suggests a method for avoiding the commonly encountered difficulty in proper identification of the pericardial and epicardial echoes. Our preliminary studies suggest that serial echograms should play an important role in the management of patients with pericardial effusion; further surgical/pathological correlations are required.

Adult↗
PubMed1976

In vivo degradation of silicone rubber poppets in prosthetic heart valves.

Dynamic shear modulus G' was measured throughout the volume of three nonvariant silicone rubber poppets which were recovered from aortic prosthetic heart valves that had been implanted for 4 days, 52 days, and 8 years. Similar measurements were obtained for two unused silicone rubber poppets. Although the recovered poppets exhibited no obvious physical evidence of damage, the silicone rubber had undergone in vivo degradation throughout the poppet volume as indicated by decreases in modulus. The measurements also indicate that the poppet surface degrades at a rate faster than the core. Further, comparison with data reported in the literature suggests that the surfaces of variant poppets degrade at a rate faster than the surfaces of nonvariant poppets.

Aortic Valve↗