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Biomedical subjects

F Y Lau

Publications and source records attributed to F Y Lau.

At least 19 recordsLinked to original sources
PubMed1992

Percutaneous closure of a secundum atrial septal defect and double balloon valvotomies of a severe mitral and aortic valve stenosis in a patient with Lutembacher's syndrome and severe pulmonary hypertension.

This is a 43-yr-old female presenting with recurrent atrial septal defect, closed surgically, 10 years prior, severe aortic and mitral stenosis, and severe tricuspid regurgitation. She was considered inoperable because of the severe pulmonary hypertension and the complexity of the disease. A percutaneous umbrella closure of the atrial septal defect in conjunction with mitral and aortic balloon valvotomies could be safely and successfully performed. After significant clinical and hemodynamic improvement, surgery was judged feasible, but was refused by the patient who suddenly expired 8 weeks later. The usefulness of percutaneous therapy as a rescue procedure and the management of patients with Eisenmenger's physiology are discussed.

Adult↗
PubMed1992

Transseptal catheterization update 1992.

Resurgence of the transseptal procedure in the last decade has occurred coincident with the advent of therapeutic catheterizations and in particular mitral balloon vavuloplasty. As larger numbers of these procedures have been performed, experience shows that the position of intended septal puncture varies for each anticipated procedure and need not lie at the fossa ovalis, which is frequently displaced or inaccessible. Recognizing the dynamic alterations in septal and atrial anatomy that accompany the various combinations of valvular heart disease, the experienced interventionalist will use precatheterization echo and radiological techniques to enable precise and localized transseptal puncture. Using these techniques in 597 patients for valvular heart disease, we have had no deaths and a morbidity of 1.8% with the transseptal puncture.

Cardiac Catheterization↗
PubMed1992

Comparison of Inoue single-balloon versus double-balloon technique for percutaneous mitral valvotomy.

The results of percutaneous mitral valvotomy by means of the Inoue single-balloon (N = 85, group 1) and the double-balloon (N = 322, group 2) techniques were compared in a nonrandomized study. The groups were not significantly different with regard to age, sex, calcification, or hemodynamic values before percutaneous mitral valvotomy. After percutaneous mitral valvotomy, patients in both groups had significant hemodynamic and clinical improvement. The increases in mitral valve area and cardiac output and the decreases in mitral valve gradient, mean pulmonary artery pressure, and mean left atrial pressure were greater in group 2. Mitral valve area determined by the Gorlin method increased 191% in group 2 and 106% in group 1; Doppler-determined mitral valve area increased 133% in group 2 and 98% in group 1. Optimal results were achieved in 93% of the patients in group 2 and 76% in group 1 (p less than or equal to 0.0001). In group 1, 6% of patients had a left-to-right shunt as shown by angiography versus 14% in group 2 (p less than or equal to 0.05). In group 2, 46% of patients had at least a 1+ increase in mitral regurgitation versus 52% in group 1. Among the patients who had an increase in mitral regurgitation, 36% of those in group 1 versus 9% in group 2 had a 2+ or more increase (p less than or equal to 0.001). The mean balloon diameter to anulus ratio was larger in group 2, and the larger the balloon diameter to anulus ratio, the greater the increase in mitral valve area.(ABSTRACT TRUNCATED AT 250 WORDS)

Catheterization↗
PubMed1991

Congenital atresia of left main coronary artery: proposed mechanism for severe disabling angina in a patient with non-atherosclerotic single right coronary artery--a case report.

A patient with progressive disabling angina was found to have a single right coronary artery with atresia of the left main coronary artery, and absence of any obstructive coronary disease. The patient required aortocoronary by-pass surgical reconstruction of a left main coronary artery to control her angina. Possible mechanisms for the development of her anginal pain are briefly discussed.

Angina Pectoris↗
PubMed1990

Percutaneous double balloon valvotomy for severe rheumatic mitral stenosis.

Percutaneous double balloon valvotomy for severe rheumatic mitral stenosis was successfully performed in 281 of 285 consecutive patients. The changes evoked were a decrease of the mean transvalvular gradient from 16 +/- 7 to 5 +/- 3 mm Hg, an increase in cardiac output from 3.8 +/- 1.0 liters/min to 5.4 +/- 1.5 liters/min and an increase in mitral valve area from 0.86 +/- 0.24 cm2 to 2.41 +/- 0.54 cm2. The mean pulmonary artery pressure decreased from 37 +/- 13 mm Hg to 27 +/- 12 mm Hg and the pulmonary vascular resistance decreased from 307 +/- 181 to 238 +/- 122 dynes/s/cm-5. Symptomatic improvement occurred in 272 of the 285 (95%) patients. There were 3 procedure-related deaths (1%). Postdilatation mitral regurgitation was not significant in most patients. Therefore, this procedure can be performed at a low risk with effective results and a fast recovery.

Adult↗
PubMed1990

Balloon valvotomy.

Explore the source record for details and available documents.

Catheterization↗
PubMed1988

Percutaneous double balloon aortic valvuloplasty in an adult patient with calcific aortic stenosis and a Bjork-Shiley prosthetic mitral valve.

Percutaneous transluminal balloon valvuloplasty is a new technique in interventional cardiology which to date has been applied successfully in the dilatation of all four cardiac valves. Although the different techniques appear to be quite effective, the safety of these procedures has not been fully explored. In particular, because of the close anatomic relationship of the aortic and mitral annuli, the safety of aortic valvuloplasty in patients with mitral valve prosthesis is unknown. Therefore, we report the applicability of a percutaneous double balloon valvuloplasty in an elderly patient with calcific aortic stenosis and a Bjork-Shiley mitral valve prosthesis.

Aged↗
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↗
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↗
PubMed1977

Distortions in infant electrocardiograms caused by inadequate high-frequency response.

Frank lead ECG's from infants were studied for frequency content by introducing low-pass filters of 50, 75, 100, and 150 150 Hz bandwidths before obtaining computer measurements. Results indicated that a minimum bandwidth of 100 Hz is required to avoid amplitude error of 10 per cent or greater. This bandwidth requierement is essentially the same as that required for adult ECG's despite the fact that infant QRS durations are usually about half those of adults. Although the average infant ECG spectrum is likely to contain higher frequencies than the average adult ECG spectrum, duration values for Q, R, and S waves overlap in these populations to such an extent that bandwidth requirements are practically identical.

Electrocardiography↗
PubMed1977

Computer analysis of changes in frank vectorcardiograms of 666 normal infants in the first 72 hours of life.

Frank vectorcardiograms (VCGs) were collected on magnetic tape for 666 normal newborn infants at 1, 6, 12, 24, 36, 48, 60, and 72 hours after birth and analyzed by computers. The final total included 1,337 VCGs for white babies and 413 for blacks. No previous report has been made for the normal neonate with such a large sample, and no previous substantiation exists of possible age or sex differences at this early age. This study establishes a statistically significant change in vectorcardiographic patterns over the first three days, specifically in the measurements P duration, QRS duration, maximal spatial QRS amplitude, S in lead x, and T in lead z, as well as for several time-normalized QRS vectors. (P less than or equal to .005.) Racial differences were significant for T waves in lead z. This study supports the use of vectorcardiographic standards sensitive to the age of the newborn as well as to race.

Age Factors↗