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Biomedical subjects

F Ballantyne

Publications and source records attributed to F Ballantyne.

18 recordsLinked to original sources
PubMed1992

Improved detection of infective endocarditis with transesophageal echocardiography.

The incremental advantage of transesophageal echocardiography was determined by comparing results of paired transthoracic and transesophageal echocardiographic examinations performed in 61 patients for evaluation of suspected infective endocarditis. According to clinical and pathologic data, 31 of 61 (51%) patients had finding that were positive for infective endocarditis. Studies were graded as positive or negative for vegetations and were also graded for image quality. The sensitivity of transesophageal echocardiography in detecting vegetations was 88% versus 30% for transthoracic studies (p less than 0.01). For patients with aortic valve infective endocarditis, transesophageal sensitivity was 88% versus 25% for transthoracic sensitivity, because transesophageal echocardiography successfully separated vegetations from chronic valve disease caused by sclerosis or calcification (p less than 0.01). For patients with mitral valve infective endocarditis, transesophageal sensitivity was 100% versus 50% for transthoracic sensitivity, because transesophageal echocardiography distinguished vegetations from myxomatous changes or detected vegetations on prosthetic valves (p less than 0.01). Thus transesophageal echocardiography improves recognition of infective endocarditis, particularly in the presence of underlying valvular disease.

Aortic Valve↗
PubMed1990

Estimation of paraproteins by immunoturbidimetry and electrophoresis followed by scanning densitometry.

A comparison of paraprotein estimation by immunoturbidimetry (IT) and electrophoresis followed by scanning densitometry (EFD) showed significant differences in concentration for IgG, IgA, and IgM paraproteins. Overestimation of IgM paraproteins by IT was particularly marked. Our data suggest that both techniques should be used for IgG and IgA paraproteins but for IgM paraproteins IT was found to be unsuitable and EFD is the method of choice.

Blood Protein Electrophoresis↗
PubMed1986

The difficult diagnosis of hypokalemia.

The electrocardiographic diagnosis of uncomplicated hypokalemia rests on ST segment depression, a decrease in T-wave amplitude, prominent U waves and a U-wave to T-wave ratio of greater than 1. The diagnosis is more difficult in a patient receiving digitalis, but the upsloping ST segment of digitalis can be distinguished from that of hypokalemia. The changes of hypokalemia are most apparent in leads V2 and V3.

Atrial Fibrillation↗
PubMed1983

Effects of glucose on the transmembrane potential of hypoxic canine ventricular muscle fibers.

Since the introduction of glucose-insulin-potassium therapy for acute myocardial infarction 20 years ago, there have been many attempts to determine the efficacy of this treatment. Some trials have shown that this therapy is antiarrhythmic and others have found no benefit. In this study we demonstrate that concentrations of glucose found to be antiarrhythmic in recent clinical trials exert favorable effects on resting membrane potential, overshoot, and rising velocity in hypoxic canine heart cells. The refractory period, shortened by hypoxia, is also significantly lengthened by extra glucose. All of these single-cell effects are potentially antiarrhythmic and may explain the effectiveness of this therapy.

Animals↗
PubMed1975

Cellular basis for reversal of hyperkalemic electrocardiographic changes by sodium.

We examined the hypothesis that reversal of hyponatremic hyperkalemic electrocardiographic changes through the infusion of saline solutions was due to the action of sodium ion in increasing the action potential rising velocity which is depressed when the cell is exposed to increasing concentrations of potassium. Using standard microelectrode techniques, the rising velocity of canine ventricular cells was shown to increase by 21%, whereas conduction time between two microelectrodes decreased 17% when the sodium concentration of the perfusate was increased from 120 to 163 mM in 2.7 mM potassium solution. When these cells were exposed to identical increases in sodium concentration in a 7.7-mM potassium solution, rising velocity increased 55% (P less than 0.005), whereas interelectrode conduction time decreased 33% (P less than 0.05). Similar changes were noted in experiments on human ventricular cells. These experimental findings are consistent with the hypothesis stated above.

Action Potentials↗
PubMedDate not supplied

Effect of carbohydrate restriction on lipoprotein abnormalities in maturity-onset diabetes mellitus.

Hyperlipoproteinemia occurs commonly in diabetics and may contribute to early atherosclerosis in these patients. The effect of dietary carbohydrate restriction on lipid abnormalities has been examined in 42 newly diagnosed maturity-onset diabetics, in whom plasma lipoproteins were measured before treatment was started and at regular intervals during ten months of dietary therapy. Twenty-four patients (57%) had abnormal lipids when diabetes was first diagnosed. Nine were classed as Type II and 15 as Type IV hyperlipoproteinemia. Plasma lipids reverted to normal in half these patients after dietary treatment for one month. Only 8 diabetics (19%) showed persistent lipid abnormality after ten months' treatment: all had been unable to diet satisfactorily as judged by persisting obesity and hyperglycemia. The common lipoprotein abnormalities of maturity-onset diabetes can usually be returned to normal by the simplest possible carbohydrate-restricted diet, if patients adhere to this. Specialized and complex diets or lipid-lowering drugs are unncessary in the majority of patients.

Adult↗