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Biomedical subjects

M C Petch

Publications and source records attributed to M C Petch.

At least 37 records · Page 2Linked to original sources
PubMed1986

A comparison of radionuclide methods of evaluating aortic regurgitation with observations on the effect of exercise and symptoms.

The severity of aortic regurgitation, as assessed by the radionuclide regurgitant index and Fourier amplitude ratio, was compared in 29 patients. Both methods were highly reproducible and agreed in patients with mild-to-moderate regurgitation. The regurgitant index fell with exercise. This change showed a linear relationship with heart rate, allowing the regurgitant index to be corrected for heart rate. There was general agreement between the radionuclide method and echocardiography, but the regurgitant index was unable to select patients with symptoms. The regurgitant index provides an overall guide to the severity of aortic regurgitation, but may be unreliable in the presence of deteriorating ventricular function.

Aortic Valve Insufficiency↗
PubMed1985

Oesophageal stimulation lowers exertional angina threshold.

The effect of oesophageal stimulation with acid on the exertional angina threshold was examined in 12 subjects. Each walked until the angina threshold was reached on four successive occasions; during two tests the oesophagus was instilled with 0.1 mol/l hydrochloric acid and during the other two with physiological saline. Oesophageal instillation was carried out for 20 min at rest before each walk. In 10 patients the angina point was reached after walking a significantly shorter distance on the treadmill when acid was instilled than when the saline was instilled. ST-segment changes and rate-pressure product were not significantly different during the acid and saline tests. The mechanism responsible for the reduction of angina threshold is not known. However, the effect was more pronounced in the 6 patients who had experienced regular oesophageal symptoms than in those who had not. Ischaemic heart disease and gastro-oesophageal reflux are both common, and the possibility that acid reflux may aggravate angina should be borne in mind, particularly when oesophageal symptoms are present.

Adult↗
PubMed1985

Severe constrictive pericarditis after single 16 MeV anterior mantle irradiation for Hodgkin's disease.

Severe constrictive pericarditis developed in 4 of 73 patients after single anterior 16 MeV mantle field irradiation for Hodgkin's disease. 3 patients (4.1%) died; the other had successful pericardectomy. Use of a single anterior mantle field of high-energy X-rays is clearly more hazardous than conventional opposed-field techniques, and the resulting radiation pericarditis is difficult to treat.

Adolescent↗
PubMed1985

Improved selection of patients for aneurysmectomy by combined phase and amplitude analysis of gated cardiac scintigraphy.

Twelve patients undergoing left ventricular aneurysmectomy were studied by combined phase and amplitude analysis of gated blood pool scintigraphy before and after operation, to establish whether the presence of paradoxical systolic movement, as defined by this method, influenced the result of surgical treatment. There was a significant increase in the ejection fraction after operation in those patients with paradoxical systolic movement and no improvement in those with akinesis. The extent of the increase in ejection fraction was related to the size of paradoxical segment resected. It is argued that this improvement in left ventricular function reflects a reduction in the left ventricular and diastolic volume and improved efficiency of ejection of the stroke volume, resulting from resection of the scar. Combined phase and amplitude analysis may help in selecting patients most likely to benefit from aneurysmectomy.

Adult↗
PubMed1985

Are the clinical benefits of oral prenalterol in ischaemic heart failure due to beta blockade? A six month randomised double blind comparison with placebo.

The clinical effects of the oral beta 1 partial agonist, prenalterol, were investigated in 37 patients (29 male, eight female; mean age 57 years) with chronic ischaemic left ventricular failure using a placebo controlled randomised double blind protocol over six months. All patients were limited by dyspnoea (New York Heart Association class III) despite treatment with digoxin and diuretics. Twenty eight patients completed the protocol. Moderate clinical improvement was seen in the prenalterol group, whereas there was little change in the placebo group. Bicycle exercise capacity increased over six months in the prenalterol and placebo groups but only achieved statistical significance for prenalterol when compared with baseline values. Maximum exercise heart rate was significantly reduced in the prenalterol group compared with placebo. Radionuclide left ventricular ejection fraction at rest and during exercise and cardiothoracic ratio showed no significant improvement in either group over six months. Prenalterol was well tolerated and produced no increase in frequency of angina or ventricular arrhythmias. Prenalterol produced clinical benefits and improved exercise tolerance while reducing exercise heart rate. A moderate placebo response was noted. The apparent beta blocking effect of prenalterol may be as important as the beta 1 agonist effect in producing these benefits. Prenalterol has, however, been withdrawn because of side effects in animals.

Adrenergic beta-Agonists↗
PubMed1985

Does left ventricular aneurysmectomy improve ventricular function in patients undergoing coronary bypass surgery?

Fourteen consecutive patients undergoing left ventricular aneurysmectomy and coronary artery bypass grafting were studied by multiple gated ventricular scintigraphy at rest and during exercise before and at six weeks and six months after surgery. All had congestive heart failure and 12 angina pectoris. Before operation left ventricular ejection fraction fell significantly with exercise, as did the regional wall motion score. Six weeks after surgery all surviving patients were free of angina, with an improvement in functional class; the total exercise workload improved significantly, but resting left ventricular ejection fraction was unchanged; the regional wall motion score improved in both the anterior and left anterior oblique projections, although extensive areas of abnormal contraction persisted. Exercise left ventricular ejection fraction improved significantly after operation at six weeks, and previous exercise induced abnormalities of regional contraction were abolished. Six months after operation angina pectoris had recurred in one patient, but there was no further change in ventricular function in the remainder. Although resting ejection fraction is not improved, symptoms, exercise workload, and exercise ventricular function can be improved by aneurysmectomy and coronary artery bypass grafting, but the respective contribution of these two procedures remains uncertain.

Adult↗
PubMed1985

Quantification of intracardiac shunts by gold-195m, a new radionuclide with a short half life.

Gold-195m, a radionuclide with a short half life (30.5 s) was used to quantify left to right intracardiac shunts. The results of this method were compared with those obtained with technetium-99m, a method that was validated against oximetry. In five patients the pulmonary to systemic flow ratio (greater than 3:1) obtained by both radionuclides indicated that the level of shunting was too high to be measured accurately. In one patient fragmentation of the bolus meant that no satisfactory gamma fit could be obtained. In the remaining 16 patients there was no significant difference between two successive 195mAu studies. The agreement between 99mTc results and 195mAu results was excellent. Oxygen administration, straight leg raising exercise, and the use of oblique projections did not affect the values of the pulmonary to systemic flow ratio. The technique of quantification of intracardiac shunts by 195mAu gives reproducible and accurate results and the low radiation dose means that it is suitable for use in children with suspected left to right shunts.

Adolescent↗
PubMed1984

Arrhythmias after coronary bypass surgery.

Ninety patients undergoing coronary bypass surgery were studied prospectively by bedside and subsequent ambulatory electrocardiographic monitoring to investigate the incidence, possible causes, and prevention of atrial fibrillation. Patients with good left ventricular function were divided randomly into a control group or groups treated with digoxin or propranolol. In the control group the incidence of atrial fibrillation was 27% and of significant ventricular extrasystoles 3%. Propranolol reduced the incidence of atrial fibrillation (14.8%), whereas digoxin had no effect and increased the incidence of ventricular extrasystoles. Age, sex, severity of symptoms, cardiomegaly, heart failure, previous myocardial infarction, and number of grafts did not affect the result. The operative myocardial ischaemic time was related to the occurrence of atrial fibrillation. There was also a significant relation between atrial fibrillation and bundle branch block. Atrial fibrillation is common after coronary artery grafting; it may be due to diffuse myocardial ischaemia or hypothermic injury. The incidence may be reduced by beta blockade.

Adult↗
PubMed1984

Acute haemodynamic effects of oral prenalterol in severe heart failure.

The acute haemodynamic effects of oral prenalterol were studied in 14 patients with severe heart failure (NYHA class III) due to ischaemic heart disease. All had received treatment with digoxin, diuretics, and in most cases vasodilators. Prenalterol was administered at two hourly intervals to give cumulative doses of 20, 50, and 100 mg and mean plasma concentrations of 53, 97, and 175 nmol/l. Haemodynamic measurements were made two hours after each dose with Swan-Ganz catheterisation; cardiac output was measured by thermodilution. There were no significant changes in heart rate, mean arterial pressure, or pulmonary artery diastolic pressure after the drug. Cardiac index rose significantly after 50 mg and 100 mg prenalterol. Oral prenalterol has a beneficial short term haemodynamic effect in patients with severe heart failure. If this effect is sustained prenalterol may be of value in the long term management of patients with this disabling condition.

Adrenergic beta-Agonists↗
PubMed1984

Computed tomography in patients with hypertrophic cardiomyopathy.

Computed tomography was undertaken in nine patients (age range 33-69 (mean 48.7) years) with hypertrophic cardiomyopathy. The ventricular septum was demonstrated in each patient and shown to be thickened (mean 25 mm at maximum width). The results agreed with those obtained by echocardiography, except in two patients in whom computed tomography showed preferential thickening of the mid-portion of the ventricular septum. The ventricular free wall was not clearly seen. Computed tomography may prove a valuable technique in the assessment of patients with hypertrophic cardiomyopathy.

Adult↗
PubMed1983

Coronary bypasses.

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Angina Pectoris↗