To determine the effect of flecainide acetate, a Class IC antiarrhythmic drug, The medication was given to 28 patients with ventricular pacing electrodes. Eleven patients with temporary pacing electrodes (Group I) received intravenous flecainide (2 mg/kg over 10 minutes). Ten patients with chronic permanent electrodes (Group II) were given the same dose at the time of elective pulse generator change. Seven, with implanted multiprogrammable pacemakers capable of threshold analysis (Group III), were given intravenous flecainide and 5 of these were then given the drug orally for up to 3 weeks (100 mg/day increasing to 400 mg/day). In Group I the threshold measured at a pulse width of 0.5 ms rose from a control value of 0.66 to 1.44 volts after 10 minutes (p less than 0.01). In Group II the threshold rose from 1.73 to 2.13 volts (p less than 0.01) and 2 patients had total suppression of their ventricular escape rhythm for approximately one hour. In Group III patients, intravenous flecainide resulted in a rise escape rhythm for approximately one hour. In Group III patients, intravenous flecainide resulted in a rise of the pulse width threshold measured at 2.7 volts from 0.14 to 0.22 ms (p less than 0.02) and at 4.9 volts from 0.06 to 0.11 ms (p less than 0.05) after 10 minutes. After 3 weeks of oral therapy the threshold at 2.7 volts had risen to 0.11 ms /ms (p less than 0.05 after 10 minutes. After 3 weeks of oral therapy the threshold at 2.7 volts had risen from 0.09 to 0.28 ms (p less than 0.02) and at 4.9 volts from 0.06 to 0.16 ms (p less than 0.05) Flecainide significantly increased both acute and chronic thresholds and the most marked rise (greater than 200%) occurred during chronic oral therapy. Both intravenous and oral flecainide should be used with care in patients with either temporary or permanent pacing systems.
Class 1 antiarrhythmic drugs have been subdivided into 1a, 1b and 1c according to their effect on the action potential duration. The effects on the surface electrocardiogram of one drug from each subgroup were investigated in nine patients. Electrocardiographic recordings were taken during sinus rhythm and at identical atrial and ventricular paced rates. Disopyramide (1a) significantly prolonged the QT interval during sinus rhythm and at the identical paced rates, by increasing both the QRS duration and JT interval. Lignocaine (1b) significantly reduced the QT interval during sinus rhythm and at the identical paced rates, by reducing the JT interval. Lignocaine had no effect on the QRS duration. Flecainide (1c) significantly prolonged the QRS duration during sinus rhythm, but not the QTc. However the QT interval at the paced rates prolonged significantly, due entirely to an increase of the QRS duration. Flecainide had no effect on the JT interval. These characteristic electrocardiographic differences support the differentiation of class 1 drugs into three separate subgroups.
To examine whether ventricular ectopy in hypertensive older people is associated with age, the hypertensive process, or treatment, a 24-hour ambulatory electrocardiogram recording was obtained in 94 noninstitutionalized subjects aged 60-90 years with isolated hypertension and 136 noninstitutionalized normotensive subjects aged 60-82 years. A significantly higher prevalence of frequent ventricular ectopic beats (VEB greater than 100 per recording) was found in hypertensive and normotensive groups age greater than or equal to 70 years compared to age 60-69 years (44% vs 15%, P less than .01, and 28% vs 9%, P less than 01, respectively). Complex ventricular ectopy was found to be significantly increased only in the hypertensive group greater than or equal to 70 years compared to 60-69 years (53% vs 28%, P less than .05). No significant difference for any type of ventricular ectopy was found between treated and untreated hypertensive subjects. Analysis of variance of frequent ventricular ectopy showed a significant effect of age (P less than .001) but not of hypertension. Multivariate regression analysis with frequent ventricular ectopy as the dependent variable confirmed this relationship. For complex ventricular ectopy, analysis of variance showed a significant effect of hypertension (P less than .001) and age (P less than .05). Multivariate regression analysis confirmed that complex ventricular ectopy was significantly associated with hypertension (P less than .01) and age (P less than .05). In elderly subjects aging alone is associated with increased frequency of ventricular ectopy, whereas complex ventricular ectopy is more significantly related to the hypertensive process than to age.
suMMARY The evolutionary changes in left ventricular function induced by cold pressor stimulation were investigated at 90 second intervals by rapid sequential first pass radionuclide angiography using the short half life tracer gold 195m. The results in 12 subjects with normal coronary arteries were compared with those in 12 patients with coronary artery disease. Left ventricular ejection fraction fell significantly from resting values in both groups after 1 minute of cold pressor, but only in patients with coronary disease was the significant fall maintained at 2*5 and 4 minutes. In both groups, the maximum decrease in ejection fraction occurred after 1 minute, whereas the maximum rise in systolic blood pressure occurred after 2*5 minutes. New
SummaryOne-hundred and ten patients referred for echocardiography to exclude a cardiac source of cerebral emboli were prospectively studied. Four patients with known cardiac abnormalities, for which they were receiving inadequate anticoagulation, were excluded from the study, and 18 patients were subsequently found to have a non-embolic cause for their cerebral pathology. Twenty-eight patients with a normal clinical examination, chest X-ray and electrocardiogram, and 27 patients with hypertension alone had echocardiograms which did not reveal a cardiac source of embolus. Of the remaining group of 33 patients, six were found to have a probable cardiac source of embolus and nine had abnormalities which may be associated with cerebral emboli. Echocardiography may not be indicated in patients with a normal clinical examination, chest X-ray and electrocardiogram, and in patients with hypertension alone. However, if these patients are excluded echocardiography gives a high yeld of positive findings which may be of practical importance in the management of the patient.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.