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Biomedical subjects

M F Shiu

Publications and source records attributed to M F Shiu.

51 records · Page 3Linked to original sources
PubMed1983

Echocardiographic evaluation of cardiac size and function in dialysis patients.

M-mode echocardiography was performed on 43 maintenance hemodialysis patients and 3 patients on continuous ambulatory peritoneal dialysis (CAPD). Only seven patients had completely normal echocardiograms. Nine patients (20%) had pericardial effusions and 20 patients (44%) had left ventricular dilatation. Left ventricular hypertrophy was present in 26 patients (57%): in 18 patients this took the form of concentric hypertrophy and in 8 patients there was asymmetric septal hypertrophy. Left ventricular function was depressed in 12 patients (27%). Left ventricular dilatation was more common in patients with multiple vascular accesses, who also tended to have lower hematocrit values. Left ventricular hypertrophy tended to be more common in patients with prolonged hypertension and with excessive inter-dialytic weight gains. Younger patients and those who had been on dialysis for a longer period had less cardiac abnormalities, suggesting that chronic dialysis might reverse these changes. Echocardiography was more sensitive than chest X-ray and ECG in detecting clinically unsuspected abnormalities and provides useful information in the overall evaluation of maintenance dialysis patients.

Adolescent↗
PubMed1981

Significance of normal septal motion in total anomalous pulmonary venous drainage.

Paradoxical septal motion is considered to be a characteristic feature of total anomalous pulmonary venous drainage, reflecting the right ventricular volume overload in this condition. Patients with additional pulmonary venous obstruction have reduced pulmonary blood flow, and would be expected to show normal septal motion. We have studied the haemodynamic and echocardiographic findings in 21 patients with proven total anomalous pulmonary venous drainage and found paradoxical septal motion in only 11 instances. Paradoxical septal motion was present in all nine patients over the age of 1 month. Of the 12 neonates, 10 showed normal septal motion. Patients with normal septal motion had clinical features of pulmonary venous obstruction, with significantly higher pulmonary artery pressures and lower pulmonary artery saturations than patients with paradoxical septal motion. It is concluded that in total anomalous pulmonary venous drainage, septal motion reflects pulmonary blood flow, allowing separation of patients into those with or those without pulmonary venous obstruction.

Child, Preschool↗
PubMed1981

Acute effects of haemodialysis on left heart dimensions and left ventricular function: an echocardiographic study.

Carotid pulse tracings and M-mode echocardiography were recorded in 25 patients on maintenance haemodialysis pre- and post-dialysis. Myocardial function, as assessed by fractional shortening and velocity of circumferential fibre shortening, was depressed in 7 out of 25 patients pre-dialysis (28%). Acute Haemodialysis resulted in significant changes in body weight, mean arterial pressure, urea, creatinine and packed cell volumes in all patients. Left ventricular function, however, improved significantly only in that group of patients in which it was depressed prior to dialysis. Echocardiography provides a simple means for evaluating left ventricular function in patients on chronic haemodialysis and shows that cardiac performance improves with acute dialysis when it is depressed pre-dialysis.

Adolescent↗
PubMed1981

Oral prostaglandin E2 in ductus-dependent pulmonary circulation.

Prostaglandin E2 (PGE2) was administered orally, in doses of 12-65 microgram/kg at intervals of 1-4 hours, to 12 neonates in whom the pulmonary circulation depended on patency of the ductus arteriosus. After an oral dose, both oxygen saturation (SaO2) and plasma PGE2 concentration increased consistently within 15-30 minutes, reaching values comparable to those during i.v. infusions. Treatment continued for 5 days to 4 months. In eight infants, PGE2 withdrawal resulted in a decrease of SaO2, from a mean of 75 +/- 7% to 57 +/- 10% (+/- SD). The ductus remained responsive for long periods--in four infants, for over 3 months. Consequently, surgery could be delayed until the infants and their pulmonary arteries had grown. Side effects during oral therapy were similar to those during i.v. infusion but were less severe in this series. The effectiveness and simplicity of oral PGE2 administration have advantages over i.v. administration, especially for long-term treatment.

Administration, Oral↗
PubMed1981

Hemodynamic effects of atrial pacing and prenalterol infusion in patients taking beta-adrenergic blocking drugs.

Prenalterol, a beta-adrenergic agonist, was given to nine patients with angiographically proved coronary artery disease. Subjects were studied during chronic beta-adrenergic blockade. The adequacy of blockade was assessed by the exercise heart rate response and by plasma concentrations of blocking agents. After incremental doses of 2.5 mg, 5.0 mg and 7.5 mg of prenalterol, heart rate was increased by 20%, 24% and 38%, respectively, and left ventricular dP/dt max by 55%, 73% and 61%, respectively. Systolic and diastolic blood pressures did not change significantly; pulmonary artery wedge pressure fell from 10 +/- 0.5 mm Hg to 7.1 +/- 0.9 and 6.7 +/- 0.7 mm Hg after 2.5 mg and 5.0 mg, respectively (p less than 0.01 for both). The net inotropic response to prenalterol was assessed, independent of the chronotropic response, using incremental atrial pacing before and after drug infusion. At identical heart rates, left ventricular dP/dt max increased by 40%, 49% and 48% after 2.5 mg, 5.0 mg and 7.5 mg, respectively. Left ventricular cineangiography before and after infusion showed an increase in ejection fraction from 0.73 +/- 0.02 to 0.83 +/- 0.03 (p less than 0.001). Plasma prenalterol concentration estimations demonstrated a clear, dose-related inotropic response, the level of response in each patient being largely determined by the degree of beta-adrenergic blockade at the time of the study.

Adrenergic beta-Antagonists↗
PubMed1980

The straight back syndrome.

The straight back syndrome, consisting of loss of normal upper thoracic spinal curvature associated with cardiac murmurs and radiographic cardiomegaly is considered a form of 'pseudoheart disease' which has been attributed to squashing of the heart in the reduced AP diameter of the chest. During an 18-month period 31 patients referred to a cardiologist were found to have a straight back. Forty-five relatives were subsequently examined and 27 were found also to have a straight back. Palpitations and chest pain were the commonest symptoms. On the lateral chest radiograph the distance from the middle of the anterior border T8 to a vertical line connecting T4 and T12 was found to be significantly reduced compared to controls, and a value less 1.2 cm is indicative of a straight back. Of the 58 subjects with the syndrome, 39 (67 per cent) had clinical and/or echocardiographic evidence of mitral valve prolapse. Respiratory function testing revealed no significant abnormality. HLA typing showed no association with an particular HLA antigen but indicates that the straight back syndrome is inherited as an autosomal dominant condition and suggested that the antigenic determinants may be located on chromosome 6. We conclude that the straight back syndrome should no longer be considered a form of pseudoheart disease and patients should be investigated for associated mitral valve prolapse and their relatives screened.

Adolescent↗
PubMed1979

Echocardiographic findings in prolapsed aortic cusp with vegetation.

A patient with severe aortic regurgitation showed abnormal echoes in the left ventricular outflow tract compatible with aortic vegetation or flail aortic cusp. At operation, a pedunculated vegetation on a prolapsed aortic cusp was found. The case illustrates some of the pitfalls in the echocardiographic distinction of the two conditions.

Adult↗
PubMed1979

Echocardiographic and exercise evaluation of results of mitral valvotomy operations.

M-mode echocardiography was performed in 54 patients 1 month to 3 years after mitral valvotomy for dominant mitral stenosis. The mitral valve closure index (MVCI), an index previously shown to correlate well with the calculated mitral valve area, was used to diagnose residual mitral stenosis. Using the equation MVCI = 33 MVC--12, 12 patients (22%) were deemed to have mild, 4 (7%) moderate, and 2 (4%) severe residual stenosis. Repeat cardiac catheterisation confirmed the diagnosis in 7 patients. The postoperative mitral valve closure index correlated significantly with patients' subjective symptoms and objective exercise indices. It was higher in patients in whom the posterior mitral leaflet movement became normal after valvotomy, and was lower in patients in whom the anterior mitral leaflet excursions below 14 mm before operation. The mitral valve closure index is a sensitive index for diagnosing residual mitral stenosis after valvotomy.

Adolescent↗
PubMed1979

Sarcoma obstructing right ventricular cavity: clinical, echocardiographic, haemodynamic and angiographic features.

Right atrial hypertension and pericardial effusion developed 2 years after mastectomy for fibrosarcoma. Clinical and echocardiographic features suggested right ventricular tumour. At catheterization the right ventricular cavity was almost obliterated, with an infundibular gradient of 13 mmHg, and biopsy of the mass was attempted. Post-mortem revealed extensive infiltrating and intracavitary right ventricular fibrosarcoma without extracardiac tumour.

Echocardiography↗
PubMed1978

Echocardiographic analysis of posterior mitral leaflet movement in mitral stenosis.

Echocardiographic analysis of the movement of the posterior mitral valve leaflet in 60 patients with lone mitral stenosis, 35 patients with aortic stenosis, and 18 patients with aortic and mitral stenosis showed a spectrum of initial posterior mitral valve leaflet movement in early diastole. The classical anterior movement was seen in 36 out of 60 patients with mitral stenosis (60%), and 8 out of 16 patients with aortic and mitral stenosis (50%). Normal posterior movement was present in all patients with lone aortic stenosis but was also seen in 10 patients (17%) with mitral stenosis and 6 patients (33%) with aortic and mitral stenosis. The remaining patients with mitral stenosis or aortic stenosis and mitral stenosis showed a biphasic type of initial movement. Patients with anterior movement had a mean calculated mitral valve area from cardiac catheterisation significantly smaller than the rest (P less than 0.001), but neither biphasic nor posterior movement excluded severe mitral stenosis. The distinction between patients with mitral stenosis and initial movement of the posterior mitral valve leaflet and patients with left ventricular discompliance is possible when there is sinus rhythm. Late diastolic anterior movement of the posterior mitral valve leaflet during atrial contraction is diagnostic of true mitral stenosis.

Aortic Valve Stenosis↗
PubMed1978

Pulmonary vein blood flow velocity in pulsus paradoxus.

The effect of inspiration on pulmonary vein blood flow velocity and forward pressure gradient from pulmonary vein to left atrium was studied in seven patients with chronic constrictive pericarditis, five of whom had clinically obvious pulsus paradoxus. Compared to patients without pericardial disease, where inspiration produced no change, patients with pericardial disease showed an inspiratory fall in the forward pressure gradient and forward blood flow velocity in the pulmonary veins on inspiration. The mechanism of pulsus paradoxus in these patients can be explained by incomplete transmission of the inspiratory fall of intrathoracic pressure to the left atrium.

Adult↗
PubMed1977

Mitral valve closure index. Echocardiographic index of severity of mitral stenosis.

A new echocardiographic index of mitral valve diastolic closure, based on the rate of diastolic apposition of the anterior and posterior mitral leaflet echoes, was measured in 40 patients with mitral stenosis. This mitral valve closure index correlated highly significantly with the mitral valve orifice area (calculated from the Gorlin formula) (r = 0-87). Correlation between the diastolic closure rate (based) on the EF slope) and the calculated valve area was poor (r = 0-37). It is proposed that the mitral valve closure index excludes movement extraneous to the mitral apparatus and expresses the actual rate of valve closure, thus avoiding some of the factors known to contribute to the poor specificity of the diastolic closure rate. The better correlation of the mitral valve closure index with the calculated valve orifice area makes it possible to assess the severity of mitral stenosis by echocardiogram with greater accuracy and confidence.

Adult↗