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Biomedical subjects

R H Baxter

Publications and source records attributed to R H Baxter.

12 recordsLinked to original sources
PubMed1979

Monitoring ventricular function at rest and during exercise with a nonimaging nuclear detector.

A portable nonimaging device, the nuclear stethoscope, for measuring beat to beat ventricular time-activity curves in normal people and patients with heart disease, both at rest and during exercise, is being developed and evaluated. The latest device has several operating modes that facilitate left ventricular and background localization, measurement of transit times and automatic calculation and display of left ventricular ejection fraction. The correlation coefficient of left ventricular ejection fraction obtained with the device and with a camera-computer system was 0.92 in 35 subjects. During bicycle exercise the ejection fraction in 15 normal persons increased from 44 to 64 percent (P less than 0.001), whereas among 12 patients with heart disease it was unchanged in 5 and decreased in 7.

Adult↗
PubMed1979

Acute lead poisoning: an unusual cause of hepatitis.

Four patients, aged 17 to 25 years, obtained lead and opium pills which had been stolen from retail pharmacists. They crushed them, suspended them in water an injected them intravenously. They developed general malaise, vomiting and constipation, and blood tests several weeks after injection of the pills showed raised alkaline phosphatase and aspartate transaminases. All four patients had negative tests for the hepatitis B surface antigen. Liver biopsy specimens showed persistent hepatitis in one and resolving hepatitis in the remaining three. Liver lead levels were grossly elevated in every case. The liver lead levels found it the patients described here were up to 35 times greater than levels which have been reported in industrial lead poisoning. It is postulated that the livers of patients with chronic lead poisoning are able to withstand this insult whereas in the cases described the overwhelming dose of lead was sufficient to cause hepatic damage.

Adult↗
PubMed1978

Relation of angina to coronary artery disease in mitral and in aortic valve disease.

Of 129 patients with either mitral or aortic valve disease angina was present in 55 (42%). It was more frequent in aortic (60%) than in mitral valve disease (33%). The standard 12-lead electrocardiogram was not helpful in distinguishing underlying occlusive coronary artery disease. Coronary arteriography demonstrated coronary artery disease in 26 patients (20%), only 2 of whom had no angina. The incidence of coronary artery disease was almost identical in both the mitral and aortic groups (22% and 17%, respectively), but the percentage of those with demonstrable coronary artery disease accompanying angina was much higher in the mitral group (67% as against 29%). Angina in mitral valve disorders is thus much more likely to be the result of disease of the coronary arteries. Coronary arteriography is mandatory in all patients in both groups who have angina. Otherwise it seems unnecessary as coronary artery disease was found in only 2 patients who did not have angina.

Adult↗
PubMed1977

Increased exercise tolerance with nitrates in beta-blockaded patients with angina.

In 14 beta-blockaded anginal subjects, 10 of whom had poor left ventricular function, sublingual isosorbide dinitrate significantly increased maximal exercise capacity on a standardized multistage treadmill test. This was associated with changes in heart rate and blood pressure suggestive of a fall in left ventricular work. The effect of isosorbide lasts for at least two hours and when taken before exercise may be a useful addition to beta-blockade in patients with angina.

Adrenergic beta-Antagonists↗
PubMed1977

Vasodilator therapy in acute myocardial infarction. Use of sublingual isosorbide dinitrate.

The haemodynamic effect of a long-acting vasodilator isosorbide dinitrate has been studied in 10 patients after an acute myocardial infarct, all of whom had evidence of left ventricular failure. Left ventricular filling pressure measured as the mean pulmonary artery wedge pressure was raised in all patients and fell significantly from 20+/-6 to 13+/-5 mmHg (P less than 0-001) within 10 minutes of sublingual isosorbide dinitrate. This 35 per cent fall in left ventricular preload was accompanied by significant fall in mean pulmonary artery pressure from 30+/-7 to 20+/-4 mmHg (P +less than 0-001) and mean right atrial pressure from 11+/-3 to 6+/-2 mmHg but cardiac output measured by thermodilution was unchanged. Mean systemic blood pressure was also significantly reduced. This improvement in left ventricular performance resulting from a reduction in left ventricular filling pressure and systemic blood pressure indicates that there may be a place for long-acting vasodilator in the treatment of acute myocardial infarction.

Aged↗
PubMed1975

Tricuspid valve replacement: a five-year appraisal.

Organic disease of the tricuspid valve required surgery in 18% of all patients undergoing valve replacement over a five-year period. Differentiation of organic from functional disease is difficult and may be made only at open-heart surgery. The results of a series of 56 patients who underwent tricuspid valve replacement are presented; of these, 53 had organic disease. Operative mortality at the end of five years had fallen to 7% with significant clinical improvement in 79% of patients, a reduction in cardiothoracic ratio in 81%, and a low incidence of postoperative tricuspid incompetence.

Female↗
PubMedDate not supplied

Scintillation probe detector in the assessment of cardiovascular disease.

A simple device that permits measurement of cardiac function in humans after intravenous injection of technetium-99m-labeled albumin or red blood cells is described. The device (nuclear stethoscope cardiac probe) is based on the application of microprocessor technology to a scintillation detector. It can be used to monitor ventricular function continuously and in exercise testing for the detection of coronary heart disease.

Coronary Disease↗