Number Of Premature Ventricular Contractions Research Articles

Arrhythmia During Insulin-Induced Hypoglycemia in a Diabetic Patient

The temporal relationship between the level of blood glucose and the frequency of ventricular premature contractions (VPCs) during 24 hours was examined in a 45-year-old man with diabetes mellitus who was treated with a regular insulin injection. The number of VPCs increased sharply when the blood glucose level fell to about 50 mg/dL while the patient was awake. There was a minimal increase in VPCs during sleep, despite a decrease to 21 mg/dL in the blood glucose level. The insulin tolerance test produced frequent VPCs during hypoglycemia, which was suppressed by glucose administration. Changes in the level of plasma epinephrine correlated well with changes in the frequency of VPCs. These data suggest that increased levels of plasma epinephrine may have played a role in the genesis of VPCs that occurred during insulin-induced hypoglycemia.

Increased Ventricular Ectopy and Sleep Apnea following Ethanol Ingestion in COPD Patients

The effects were assessed of ingestion of 1 ml/kg of 100 proof vodka on sleep-disordered breathing, nocturnal oxygen desaturation, and ventricular ectopy in patients with chronic obstructive pulmonary disease (COPD). Ethanol ingestion (mean blood alcohol concentration of 40 mg/dl) was associated with a significant increase in the number of premature ventricular contractions (PVCs) per night and the number of PVCs per hour of sleep-period time, but was not associated with other ventricular dysrhythmias. Ethanol also increased the number of episodes of apnea, total duration of apnea, and the number of episodes of apnea per hour of total sleep time, but there was no significant change in hypopnea or oxygen desaturation. Ethanol decreased total sleep time but did not significantly alter sleep stage distribution. This study demonstrates that moderate ethanol consumption increased ventricular ectopy and sleep apnea in patients with COPD.

The usefulness of Holter monitoring in the evaluation of antiarrhythmic drug efficacy for tachycardia.

Using Holter monitoring tachycardia was found in 145 out of 2058 patients suffering from various underlying diseases. Three thousand seven hundred and forty monitorings were performed. The mean age of patients was 54.5 years with a range of 19 to 83 years. The observed tachycardia was classified into three types: tachycardia with short duration, tachycardia with long duration and tachycardia with complex form. The attacks of tachycardia were more frequently observed during periods of physical activity than during sleeping periods. The relationship of the number of tachycardia with short duration between 24-hour Holter monitorings was examined in order to establish day to day variability of the attacks. The 95% confidence interval about the resultant regression line was calculated and the percent reduction required for the evaluation of drug efficacy to avoid the chances of interference of spontaneous variation was found to be about 44.0, 55.0 and 82% when the total number of attacks during a 24-hour period were 50, 100 and 1,000, respectively. Holter monitoring showed higher positive results as compared to exercise testing for detection of tachycardia. Higher correlation coefficients between numbers of premature ventricular contractions (PVCs) and the plasma concentrations of procainamide or N-acetylprocainamide were observed in 3 or more successive PVCs than in individually occurring PVCs. Using repeated 24-hour Holter monitorings a significant reduction in the number of tachycardia was observed when the therapeutic concentration was reached after the combined or single administration of the drug. These results suggest that repeated Holter monitorings, exercise testing and determination of plasma level of the drug may be useful for the evaluation of antiarrhythmic drug efficacy for tachycardia.

Electrophysiologic and antiarrhythmic effects of phentolamine in experimental coronary artery occlusion and reperfusion in the dog.

We studied the electrophysiologic and antiarrhythmic effects of phentolamine on ventricular arrhythmias seen after acute coronary artery occlusion and reperfusion in the anesthetized dog. One group of animals underwent proximal left circumflex artery occlusion for 1 hr followed by 4 hr of reperfusion. One-half received phentolamine, 0.25 mg/kg bolus, 30 min before occlusion, followed by continuous intravenous infusion of 0.15 mg/kg/min throughout the experiment, while the other half received saline and served as controls. Phentolamine reduced the number of premature ventricular contractions (PVCs) during the reperfusion period but had no effect on postocclusion arrhythmias. Another group of dogs underwent ligation of two consecutive left anterior descending diagonal branches for 1 hr followed by reperfusion. Effective refractory periods and ventricular activation times were measured before occlusion, every 10 min during occlusion, and every 10 min during reperfusion in both normal and ischemic zones. In this model, phentolamine reduced both the number of PVCs and the complexity of ventricular ectopy seen in the first 10 min after reperfusion. Compared to control, phentolamine decreased the shortening of ischemic zone refractory period seen after occlusion and prevented the overshoot seen after reperfusion. Phentolamine had no effect on ventricular activation times or mean blood pressure. Phentolamine is effective in preventing reperfusion ventricular arrhythmias and may act by decreasing the dispersion of refractoriness between normal and ischemic zones during coronary occlusion and reperfusion and by preventing the rapid increase in refractory period after reperfusion.

Changes in myocardial refractory periods following ischemia in the porcine heart

Summary The purpose of this study was to utilize computer technique to analyze the time course of changes in myocardial refractory periods following coronary ligation in the porcine model in order to: o 1) compare these changes with those in the canine heart, a model with extensive coronary collateral circulation; 2) correlate alterations in refractory periods with spontaneous ventricular arrhythmias; and 3) correlate changes in refractory periods with the ability to initiate a repetitive ventricular rhythm by a premature stimulus applied near the effective refractory period. An on-line microprocessor with a real-time clock was interfaced with a sensing-stimulating unit to provide continuous determination of refractory period changes in 14 pigs in which the heart was exposed via a thoracotomy. The results were compared with the number of premature ventricular contractions (PVCs) and the ability to precipitate ventricular fibrillation by a premature ventricular stimulus. The results showed that: o 1) refractory periods in ischemic tissue were significantly reduced (p 2) both the number of PVCs per minute and changes in refractory periods increased to minute 3–4, however, the frequency of PVCs had declined significantly by minute 8–9 (20.4±16.55 vs. 1.60±2.51; p 3) the ability to initiate ventricular fibrillation was proportional to the reduction in refractory periods in ischemic tissue with fibrillation in only two of 14 animals stimulated at 0–20% vs. four of six at refractory period reductions of 20–40% (p These studies establish the distinctive time course of changes in refractory periods following ischemia in an animal without significant pre-existing coronary collateral circulation, and correlate these changes with spontaneous and induced ventricular arrhythmias.

Sleep-Waking Changes in Cardiac Arrhythmia in a Coronary Care Patient

A single case is reported in whom ventricular cardiac arrhythmias were related to the occurrence of polygraphically verified sleep. A strong relationship was found to exist between the heart rate in any one minute and the number of premature ventricular contractions, with higher rates associated with a greater number of these ectopic beats.

Arrhythmias in patients with mitral valve prolapse.

Resting ECGs, exercise treadmill tests and 24-hour ambulatory ECGs were recorded and analyzed in 24 unselected patients with mitral valve prolapse. Arrhythmias were frequent. There were three distinct groups of patients, defined on the basis of total number of premature ventricular contractions (PVCs) during the 24 hours; there were no PVCs in 25%, and frequent PVCs in 50%. Complex ventricular arrhythmias, including ventricular tachycardia in five patients, were found almost exclusively in the group with frequent PVCs. Fifteen of the 24 patients demonstrated atrial premature contractions (APCs) during the 24 hours. Complex atrial arrhythmias were found among patients with infrequent, as well as those with frequent, APCs. Supraventricular tachycardia was detected in seven of these patients. The incidence of ACPs decreased during sleep in 67% of the patients and showed no change during sleep in 33%. A poor correlation was found between symptoms recorded in patient diaries and changes noted on 24-hour ECG recordings. The peak PVCs/15 min and peak ACPs/15 min during a 24-hour period of monitoring was found to be an excellent guide to the total number of PVCs and APCs occurring during that period. This permits an accurate prediction of the total number of PVCs in 24 hours after performing an exact PVC count on only 15 minutes of ECG data. Finally, the 24-hour ambulatory ECG was sensitive than the treadmill test and both were superior to the 12-lead ECG for detecting arrhythmias in these patients.

Diphenidol Treatment of Arrhythmias

The antiarrhythmic activity of diphenidol, an antiemetic, has been demonstrated both in electrophysiologic studies of patiens and in experimental arrhythmias in animals. Accordingly, 18 patients with tachyarrhythmias were treated with intravenous diphenidol in doses of 0.5 to 1.5 mg/kg. In six patients with atrial arrhythmias, there was no notable effect. Similarly, 12 patients with premature ventricular contractions were treated and studied. In six of them, ectopic beats were abolished, at least transiently; in three the number of ventricular premature contractions decreased; in two there was no effect; and in one, the number of premature beats was increased. Of the total number of 18 patients, 14 suffered adverse effects related to the central nervous system. These adverse effects were of such severity as to suggest that further studies with diphenidol as an antiarrhythmic are not warranted.

Intramuscularly and orally administered lidocaine in the treatment of ventricular arrhythmias in acute myocardial infarction

An intramuscular injection of 2.5 ml of 10 percent lidocaine was given to 26 cardiac patients. An effective mean plasma level (1 mg/liter or more) was reached in 5 minutes and persisted for 120 minutes; the highest mean level (2.2 mg/liter, SEM ± 0.18) was reached after 30 minutes. In 15 patients who sustained an acute myocardial infarction with premature ventricular contractions, the frequency of premature ventricular contractions was continuously recorded with an arrhythmia monitor. After intramuscular administration of lidocaine the number of premature ventricular contractions decreased by an average of 75 percent. Oral administration of 250 mg of lidocaine to 7 other patients resulted in low plasma levels and had little effect on premature ventricular contractions. No serious adverse effects on heart rate, atrioventricular conduction or blood pressure were encountered in any patient, including 5 with myocardial infarction and various degrees of heart block. It is believed that intramuscular administration of lidocaine could be useful in the prevention of sudden death due to ventricular fibrillation in the “precoronary” phase.