Ed Varnauskas

Validity and Reproducibility of Determination of Cardiac Output by Thermodilution in Man

A thermodilution technique using a dual thermistor catheter introduced in the pulmonary artery was used for the determination of cardiac output at rest in 12 patients and for the same measurement duri

Further improved method for measuring monophasic action potentials of the intact human heart

Summary A simple, safe and easily-reproduced method of recording the monophasic action potential (MAP) of the intact human heart is described. It involves the use of a special close bipolar electrode catheter. The advantages with this method compared with earlier described methods are pointed out on the basis of 57 investigations on 58 patients. Possibilities to analyze MAP from the right atrium and ventricle are illustrated in records of right atrial MAPs during sinus rhythm, atrial flutter, and fibrillation, as well as right ventricular MAPs during sinus rhythm. The method is promising in the explanation of electrocardiographical abnormalities.

Duration of beta-receptor blockade after oral administration of LB-46

SummaryThe duration of beta-receptor blockade after single oral doses of LB-46 has been investigated by the isoproterenol infusion technique. A single 5 mg dose of LB-46 caused beta-receptor blockade lasting for 45 min to about 15 h; the range of action after 10 mg LB-46 orally was 30 min to 24 h. The duration of action of an equipotent dose of alprenolol was shorter. The therapeutic implications of these results are discussed.

Computerized Exercise ECG in the Diagnosis of Critical Coronary Lesions

Different ECG criteria are evaluated with respect to their ability to identify individuals with critical lesions of the coronary arteries in a population of patients with severe angina. Six chest leads and the the limb leads were recorded in 85 patients by computer during maximal, symptom-limited exercise ECG testing. Averaging of ECG complexes enhances the signal quality and makes it possible to use measurements of the limb leads recorded during exercise. 14 patients with abnormal Q waves in lead V2 were excluded from ST analysis. In the remaining 71 patients, more than 1/3 mm ST depression in lead I and/or more than 2.0 mm ST depression in any of the chest leads had a sensitivity of 85% and a specificity of 67% for lesions in the main stem and/or proximal LAD and/or three-vessel disease. The predictive value of a positive test was 83%. This and other criteria were evaluated for different disease groups and a different stages during the exercise test.

The effect of mexiletine on the electrophysical properties of the intact human heart.

The effect of an intravenous dose of mexiletine, a new anti-arrhythmic agent, on the electrophysiological properties of the intact human heart was studied in ten subjects with no evidence of cardiovascular disease. Mexiletine produced no significant changes in the sinus node recovery time, the corrected sinus node recovery time or in the atrial, atrio-ventricular and ventricular effective refractory periods. In addition mexiletine had no significant effect on proximal atrioventricular conduction. The drug did, however, prolong atrio-ventricular conduction distal to the bundle of His in all ten subjects by an average of 6 msec. This change was statistically significant (P less than 0.01). The drug is recommended to be used with caution in patients with conduction disturbances.