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Biomedical subjects

A W Chisholm

Publications and source records attributed to A W Chisholm.

10 recordsLinked to original sources
PubMed1983

Initial experience with universal pacemakers.

Thirty-five patients were implanted with the Sequicor DDD pacemaker between September 1, 1981 and March 1, 1982. The mean age was 61.7 years (range, 17-88). According to their ECGs, the patients fell into two distinct groups--those with A-V block and those with sick sinus syndrome. Our initial experience has indicated an excellent electronic component function (except for 1 discrepant reed switch); high battery drain of the Sequicor; complications similar to those seen with DVI or VVI pacing; and an increase in the hemodynamic benefits resulting from DDD as compared to DVI or VVI pacing in 70% of patients.

Adolescent↗
PubMed1978

Coronary artery spasm and mitral valve prolapse.

Ten patients, representing 1.34 per cent of those patients undergoing selective coronary arteriography, were found to have unequivocal evidence of coronary artery spasm. This involved the proximal right coronary artery in eight patients, the mid-left anterior descending branch in one, and the left main coronary artery in one. Eight of these 10 patients had otherwise normal coronary arteries. Of these 10 patients with coronary artery spasm, nine had evidence of mitral valve prolapse. This involved the posteromedial scallop in six patients; the anterolateral and posteromedial scallops in one; the middle and posteromedial scallops in one; and the anterolateral, middle, and posteromedial scallops in one. These data suggest an association between coronary artery spasm and mitral valve prolapse. Coronary artery spasm may thus be an important factor in the pathogenesis of the chest pain, arrhythmias, electrocardiographic abnormalities, and sudden death, that have already been described in some patients with mitral valve prolapse.

Adult↗
PubMed1978

Plasma concentrations of isosorbide dinitrate and its metabolites after chronic high oral dosage in man.

1 We have previously reported that vasodilator headache due to isosorbide dinitrate (ISDN) can be circumvented by using small 'priming' doses for an induction period of 1-2 weeks, after which it is possible to increase to dose rapidly to 360-720 mg, daily without recurrence of headache and without toxicity. The present study corroborates this earlier finding. 2. Chronic oral administration of doses of ISDN of this order of magnitude results in prolonged high plasma concentrations of the parent compound, as well as higher levels of the metabolites 2-ISMN and 5-ISMN. 3. It is our thesis that chronic high oral dosage of ISDN saturates the intrahepatic biotransformation process, and allows high concentrations of ISDN and its metabolites to enter the systemic circulation.

Administration, Oral↗
PubMed1978

Permanent transvenous atrial pacing.

Atrial pacing has electrophysiologic and hemodynamic advantages for patients with symptomatic bradyarrhythmias and intact atrioventricular conduction or with certain refractory tachyarrhythmias. Permanent atrial pacing has been achieved in 29 patients followed up for periods of up to 7 years at two institutions. At Sunnybrook Medical Centre, Toronto, 16 patients have had coronary sinus electrodes introduced pervenously using standard bipolar or special unipolar catheters. Initial pacing thresholds were acceptably low (mean, 2.0 mA); chronic thresholds in three patients were similar. At the Toronto General Hospital, 13 patients had endocardial J-electrodes, bipolar or tined unipolar, inserted in the right atrial appendage. Initial thresholds were low (mean, 1.3 mA) and P-wave voltage was adequate (3.4 mV) for pacemakers with standard sensitivity. In both series, conventional R-inhibited, asynchronous or rate-programmable units have been employed. Radiofrequency self-conversion pacemakers were used in three patients. Preliminary His bundle studies were done in 10 patients; the others were tested by rapid atrial pacing during insertion of electrodes. Early and late electrode stability in both series was excellent; one electrode became dislodged from the coronary sinus position and one from the right atrial appendage.

Adult↗
PubMed1976

Control of recurrent supraventricular tachycardia with amiodarone hydrochloride.

Amiodarone hydrochloride, a new antiarrhythmic agent, controlled a recurrent supraventricular arrhythmia, refractory to conventional medical treatment, in a 57-year-old patient with an anomalous conduction system and idiopathic cardiomyopathy. For the 11 months that the patient has been taking the drug her arrhythmia has not recurred. This drug has produced no important side effects in this patient.

Amiodarone↗
PubMed1976

Relative insesitivity of isovolumic phase indices in the assessment of left ventricular function.

1. The authors compared the sensitivity of the isovolumic phase indices (contractility indices) against LV function curves ("pump-function" indices) in assessing ventricular performance. 2. Certain modifications of the usual isovolumic phase indices, especially those introducing the concept of comparison of exercise with rest, seemed to us to be slightly more helpful in separating normal subjects from the patient with coronary artery disease or cardiomyopathies, but these differences were not striking when statistically evaluated, and could not be utilized in assessment of left ventricular function in individual patients. 3. The construction of left ventricular function curves, in our hands, yielded equally as satisfactory information and, in addition, was much simpler to perform. 4. It is concluded that contractility indices are relatively insensitive in the assessment of left ventricular function, and that they offer little advantage over "pump-function" indices for this purpose.

Angiocardiography↗
PubMed1975

Left ventricular function in ischemic heart disease: assessment by noninvasive techniques.

1. Thirty-two patients (29 men and 3 women), admitted to a coronary-care unit with either acute coronary insufficiency or acute myocardial infarction, had their systolic time intervals and the a/E ratio of the apexcardiogram studied on days 1,2, and 7 of their hospital stay. 2. Only the LVETc and PEP/LVET were found to undergo any statistically significant change. Although all figures were in the abnormal range, they had no discriminative value in individuals. None of the other commonly accepted noninvasive indices or left ventricular function, including the a/E ratio of the apexcardiogram, were found to be of assistance in the early distinction between acute coronary insufficiency and acute myocardial infarction.

Acute Disease↗