Biomedical subjects

A H Dougherty

Publications and source records attributed to A H Dougherty.

26 records · Page 2Linked to original sources

PubMed1986

Electrophysiologic effects of milrinone in patients with congestive heart failure.

The electrophysiologic effects of milrinone, a new inotropic agent, have not been characterized in humans. Accordingly, 10 patients with class III or IV congestive heart failure underwent hemodynamic and electrophysiologic testing before and during an infusion of milrinone (0.5 micrograms/kg/min). Cardiac index increased from a mean of 1.65 +/- 0.51 to 2.19 +/- 0.68 liters/min/m2 (p less than 0.03) and pulmonary artery capillary pressure decreased from 30 +/- 9 to 22 +/- 9 mm Hg (p less than 0.01), without a significant change in systemic arterial pressure. Holter monitoring was performed for 48 hours at baseline and during infusion of milrinone. Frequency of ventricular premature complexes and ventricular couplets did not change significantly. Frequency of ventricular tachycardia (VT) increased significantly, although no patients would be classified as having a proarrhythmic effect based on a clinical model. PR, QRS, QTc, heart rate, AH, HV, atrial, atrioventricular and ventricular effective and functional refractory periods were not affected. Milrinone decreased 1:1 atrioventricular maximal conduction from 399 +/- 133 to 374 +/- 111 ms (p less than 0.01); ventriculoatrial conduction was not significantly affected. During programmed right ventricular stimulation, 5 patients had inducible VT at baseline (3 sustained, 2 non-sustained), whereas after drug administration, none had it (p less than 0.05). Thus, intravenous milrinone is an effective inotropic drug that also enhances atrioventricular conduction and may decrease the incidence of inducible VT in patients with congestive heart failure.

Adult↗

PubMed1986

Flecainide in the treatment of nonsustained ventricular tachycardia.

Thirty-two patients received flecainide acetate for nonsustained ventricular tachycardia after having had unsuccessful treatment with a mean of four antiarrhythmic drugs. The mean left ventricular ejection fraction was 41% in 27. Thirty-one patients had organic heart disease, and 22 patients had arrhythmia-related symptoms. Total suppression of ventricular tachycardia occurred in 22 patients. Thirty patients were discharged from the hospital receiving flecainide at a mean (+/- SD) dosage of 315 +/- 76 mg/d and 26 of these patients attained a mean trough plasma drug level of 567 +/- 254 ng/mL. One patient had proarrhythmia and 3 had worsening of heart failure. Twenty-two patients remained in the trial for a mean follow-up of 13 +/- 7 months. Five patients died (1 suddenly) during the follow-up period. Our data indicate that flecainide suppresses refractory nonsustained ventricular tachycardia in 69% of patients who have organic heart disease. Serious adverse effects were minimized by initiation of treatment in the hospital and careful surveillance of electrocardiograms and plasma drug levels.

Adult↗

PubMed1985

Electrophysiologic effects of amrinone.

Patients with congestive heart failure (CHF) have a high prevalence of complex ventricular arrhythmias. Accordingly, the electrophysiologic effects of new drugs for the treatment of CHF should be studied to determine whether they are safe in this population of patients. Fifteen patients with New York Heart Association functional classes II to IV CHF underwent hemodynamic and electrophysiologic testing during control conditions, and after 10 to 20 micrograms/kg/min of intravenous amrinone (dosages that increased cardiac output and decreased left ventricular filling pressures). All cardioactive drugs were stopped for at least 5 half-lives before entry into the study. Amrinone decreased the atrial effective refractory period from 256 to 240 ms (p = 0.015) and the AV nodal functional refractory period from 374 to 356 ms (p less than 0.05), and enhanced maximal 1:1 AV nodal conduction from 371 to 334 ms (p = 0.006). Prolonged HV intervals were present in 9 of 15 patients and were not affected by amrinone. Holter monitoring was performed in 10 patients during acute oral administration of amrinone. There were no significant changes in the frequency of ventricular extrasystoles or ventricular tachycardia, although the frequency of ventricular couples tended to increase slightly. Amrinone therefore enhances AV conduction and does not appear to have significant arrhythmogenic potential during acute administration.

Adult↗

PubMed1985

Short- and long-term experience with flecainide acetate in the management of refractory life-threatening ventricular arrhythmias.

Thirty-eight patients with organic heart disease and history of sudden cardiac arrest or recurrent sustained ventricular tachycardia were treated with flecainide. Coronary artery disease was present in 33 patients. Previous antiarrhythmic therapy consisted of two to eight drugs (mean four). Fourteen patients were resuscitated from sudden cardiac death and 24 patients had chronic recurrent sustained ventricular tachycardia. Twenty-eight patients had electrophysiologic testing before and during flecainide treatment. Sustained ventricular tachycardia became noninducible in 5 patients, nonsustained in 5 patients and slowed in 13 patients (cycle length increased from 278 +/- 64 to 395 +/- 91 ms; p = 0.002). Three of the 14 patients with sudden cardiac death and 15 of the 24 patients with recurrent sustained ventricular tachycardia remained on long-term flecainide treatment. The mean left ventricular ejection fraction in 16 of these 18 patients was 37%. Nonlimiting side effects occurred in seven patients (18%). Proarrhythmic effects were seen in four patients (10%). At a mean follow-up time of 11 +/- 3 months, 15 patients (39%) had had no recurrence, including 5 who had inducible sustained ventricular tachycardia and 5 who did not on retesting during treatment. In the 18 patients who received long-term therapy, 3 late deaths occurred, 1 of which was of arrhythmic origin. These data suggest that flecainide is effective in about 40% of patients with severe refractory ventricular arrhythmias. Its value as a single drug in the treatment of sudden cardiac death remains to be defined.

Adolescent↗

PubMed1984

Congestive heart failure with normal systolic function.

Although there have been isolated reports of congestive heart failure (CHF) with normal systolic function, the prevalence and characteristics of this condition have not previously been described. Accordingly, 188 patients with CHF undergoing radionuclide ventriculography were prospectively evaluated. Sixty-seven (36%) had a normal ejection fraction (EF) of 0.45 or greater, and 121, an abnormal EF of less than 0.45. Of these, 72 (55 with an abnormal EF [group I] and 17 with a normal EF [group II]) were also reviewed for clinical characteristics. There was no demographic difference between groups, except that systemic hypertension appeared to be a contributing factor in 65% of the patients in group II, compared with 23% of the patients in group I (p less than 0.002). Echocardiographic left atrial emptying index, reflecting left ventricular compliance, was determined in 72 patients and 14 normal subjects. Left atrial emptying index in normal control subjects was 0.93 +/- 0.11 (+/- standard deviation), compared with 0.41 +/- 0.18 in group I and 0.44 +/- 0.19 in group II patients (p less than 0.001 vs control in both groups). Thus, normal systolic function is common among patients with CHF. Diastolic dysfunction, consistent with a noncompliant left ventricle, was found in both CHF groups.

Echocardiography↗

PubMed1984

Amrinone: acute electrophysiologic and hemodynamic effects in patients with congestive heart failure.

Amrinone is an effective inotropic agent, but its electrophysiologic effects in humans have not been previously determined. Fifteen patients with congestive heart failure (CHF) New York Heart Association functional class II to IV, underwent an electrophysiologic study after withdrawal of all other cardioactive drugs before and after 10 to 20 micrograms/kg/min of intravenous amrinone (doses that increased cardiac index and decreased pulmonary capillary wedge pressure and systemic vascular resistance, p less than 0.002). Amrinone caused no change in PR, QRS, QTc, AH or HV intervals or maximal corrected sinus node recovery time and had no significant effect on the ventricular effective refractory periods. Amrinone decreased the atrial effective refractory period from 256 +/- 40 to 240 +/- 38 ms (p = 0.015), and the atrioventricular (AV) nodal functional refractory period from 374 +/- 65 to 356 +/- 64 ms (p less than 0.05), and enhanced maximal 1:1 AV nodal conduction from 371 +/- 46 to 334 +/- 47 ms (p = 0.006). Nine patients had baseline HV prolongation; this was not affected by amrinone. The frequency of inducible ventricular tachycardia was not significantly affected by amrinone. Holter recordings (24 to 48 hours) were obtained from 10 patients before and after acute oral amrinone dosing (75 to 150 mg every 8 hours). There was no change in the number of ventricular premature contractions per 24 hours (2,197 +/- 3,305 vs 2,616 +/- 2,436) or number of runs of ventricular tachycardia per 24 hours (10 +/- 12 vs 12 +/- 13); however, the number of ventricular couplets per 24 hours increased from 22 +/- 34 to 52 +/- 55 (p = 0.054).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMedDate not supplied

Amiodarone: pharmacology and antiarrhythmic and adverse effects.

Amiodarone is a benzofuran derivative that has been effective for the treatment of both supraventricular and ventricular tachyarrhythmias. It has a large volume of distribution, moderate bioavailability and a long half-life. Its pharmacokinetics are not well understood and its tissue distribution is not typical of a 2-compartment model. Due to ocular, dermatologic, gastrointestinal, neurologic, cardiovascular, thyroid and pulmonary toxicity, amiodarone should be reserved for use in patients with refractory and/or life-threatening arrhythmias.

Action Potentials↗

PubMedDate not supplied

Adverse effects of amiodarone. Pathogenesis, incidence and management.

Amiodarone is an extremely effective antiarrhythmic agent for the treatment of both life-threatening ventricular arrhythmias and refractory supraventricular tachyarrhythmias. Subjective minor side effects are common with amiodarone but rarely require discontinuation of therapy and are often handled by dose reduction. Serious end-organ toxicity, including pulmonary fibrosis and drug-induced hepatitis, have been the most common indications for discontinuing amiodarone therapy in these patients.

Amiodarone↗