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Biomedical subjects

H Abdollah

Publications and source records attributed to H Abdollah.

35 records · Page 2Linked to original sources
PubMed1989

Antiarrhythmic effects of desethylamiodarone in dogs with subacute myocardial infarction and inducible ventricular arrhythmias.

To determine if desethylamiodarone (DA), the principal metabolite of amiodarone, has antiarrhythmic activity, DA was administered intravenously (i.v.) as a 5 mg/kg bolus followed by a 2-h infusion of 8 mg/kg/h to 12 dogs with 5-7-day-old myocardial infarction and reproducibly inducible sustained ventricular arrhythmias. Programmed electrical stimulation of the right ventricle was repeated, and plasma DA concentration was determined at 15-min intervals during DA administration. At the end of the infusion, the animals were killed and DA concentration in infarcted and noninfarcted myocardium was measured. Grading and statistical analysis of induced arrhythmias revealed significant amelioration during DA infusion, with partial or complete suppression in 9 of the 12 dogs. Apparent steady-state plasma DA concentration (range 0.8-1.0 micrograms/ml) was achieved and maintained during the final 105 min of infusion. DA concentration in noninfarcted myocardium (62.6 +/- 22.0 micrograms/g) was significantly higher (p less than 0.01) than DA concentration in infarcted myocardium (25.6 +/- 18.6 micrograms/g). We conclude that DA administered i.v. has antiarrhythmic activity in dogs with subacute myocardial infarction and reproducibly inducible sustained ventricular arrhythmias.

Amiodarone↗
PubMed1989

Constrictive pericarditis and anemia post myocardial infarction.

A 67-year-old male presented with acute inferolateral myocardial infarction complicated by transient acute post infarction pericarditis. Six weeks later, he developed Dressler's syndrome associated with moderately severe anemia of chronic disease. Both of these resolved over the next few weeks, however, shortly thereafter, right sided congestive heart failure occurred. This progressed despite medical therapy and the diagnosis of constrictive pericarditis was made 10 months post infarction. Total pericardectomy was done one year after the onset of acute myocardial infarction with complete resolution of signs and symptoms.

Aged↗
PubMed1985

Continuous electrical activity during sustained monomorphic ventricular tachycardia. Observations on its dynamic behavior during the arrhythmia.

Catheter mapping was performed during sinus rhythm and monomorphic ventricular tachycardia (VT) in 56 consecutive patients with sustained, monomorphic VT. Forty-two patients had an old myocardial infarction (VT-old MI group), 6 patients had right ventricular dysplasia (VT-RV dysplasia group), and 8 patients had idiopathic VT (idiopathic-VT group). Continuous electrical activity was recorded in 15 of 42 patients of the VT-old MI group (36%), 5 of 6 of the VT-RV dysplasia group (83%), and in 0 of 8 patients in the idiopathic VT group (0%). In 17 of 20 patients with continuous electrical activity during VT, observations on the dynamic behavior of continuous electrical activity during VT revealed at least 1 of the following characteristics: spontaneous disappearance and reappearance of continuous electrical activity without changes in rate, morphologic pattern or axis of VT; pacing-induced transient termination of continuous electrical activity without termination of VT; spontaneous disappearance of continuous electrical activity during VT as a rate-dependent phenomenon; Wenckebach-like conduction to other areas resulting in transient and periodic continuous electrical activity; dependence of continuous electrical activity on ventricular activation pattern during VT; pacing-induced change from a noncontinuous electrogram into continuous electrical activity without prevention of termination of VT; and termination of continuous electrical activity after antiarrhythmic drugs without termination of VT. Continuous electrical activity was always recorded in the aneurysm and never over normal heart areas. At the sites where continuous electrical activity was recorded during VT, potentials recorded during sinus rhythm were abnormal. Our observations suggest that several electrophysiologic phenomena can simulate continuous electrical activity during monomorphic VT. Transient, continuous electrical activity is a frequent phenomenon that represents electrical activity from abnormal areas not necessarily required to perpetuate VT.

Anti-Arrhythmia Agents↗
PubMed1984

Clinical efficacy and electrophysiologic effects of intravenous and oral encainide in patients with accessory atrioventricular pathways and supraventricular arrhythmias.

The electrophysiologic effects and clinical efficacy of intravenous (i.v.) and oral encainide were studied in 13 patients with accessory atrioventricular (AV) pathways (7 overt, 1 intermittent and 5 concealed) and drug-resistant supraventricular arrhythmias (5 paroxysmal atrial fibrillation, 1 atrial tachycardia and 7 with orthodromic circus movement tachycardia). Previously, therapy had failed with a mean of 3 conventional antiarrhythmic agents. In 5 patients, amiodarone administration had also been unsuccessful. All patients underwent programmed electrical stimulation of the heart before and after 1.5 mg/kg of i.v. encainide. Seven patients were restudied during oral encainide therapy (mean 155.8 +/- 54.2 mg/day) 3 days to 6 weeks (average 21 days) later. Anterograde conduction over the accessory AV pathway blocked in 4 of 7 patients after i.v. encainide. Oral encainide blocked anterograde conduction over the accessory pathway or prolonged the refractory period of the accessory pathway in 3 of 4 patients. This change in anterograde conduction was independent of the predrug value for the anterograde refractory period of the accessory AV pathway. Intravenous and oral encainide had minimal effects on retrograde conduction over the accessory AV pathway. The clinical effect of oral encainide was studied in 12 patients. Four patients responded to oral encainide and have been free of arrhythmia or side effects for 2 to 20 months (average 10.5). Encainide failed to prevent the clinical arrhythmia in 2 patients. In 4 patients with atrial arrhythmias, circus movement tachycardia developed during oral encainide therapy. In 1 patient the frequency of circus movement tachycardia increased with oral encainide treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1984

Reproducibility of the pharmacokinetic-hemodynamic response to nitroglycerin in the dog: a model for studying the effects of chronic treatment.

We studied six dogs to determine the hemodynamic response to and pharmacokinetics of intravenous nitroglycerin (i.v. GTN) before and after a five-day treatment with placebo ointment. On the first study day, the major hemodynamic response to 21 micrograms/min i.v. GTN was an 11.4% +/- 5.6 (S.D.) fall in systolic blood pressure (SBP) from a control of 180 mmHg +/- 16 to 158 mmHg at 21 micrograms/min i.v. GTN. This finding was reproduced (a 12.6% +/- 5.6 fall in SBP) on the second study day. On the first day, the relationship between the arterial GTN concentration and the infusion rate was linear, the arterial t1/2 for GTN was short (1.9 min +/- 0.6) and there was an 80% arterial-venous extraction for GTN; these values were unchanged by five days of treatment with placebo. We conclude that this model is a sensitive and reproducible system for studying the in vivo effects of sustained drug treatment.

Animals↗
PubMed1984

Suppression of incessant supraventricular tachycardia by intravenous and oral encainide.

Although uncommon, incessant supraventricular tachycardia (the daily presence of supraventricular tachycardia for more than 50% of the day) is a major therapeutic problem. Using programmed electrical stimulation of the heart, long-term electrocardiographic monitoring and exercise testing, the effect of intravenous and oral encainide for termination and prevention of incessant supraventricular tachycardia was assessed in 11 patients (aged 25 to 58 years). All patients had received 3 to 12 drugs (mean 6) without control of their arrhythmia. Eight patients suffered from incessant supraventricular tachycardia using an accessory pathway in retrograde direction (three with overt Wolff-Parkinson-White syndrome, one with a concealed accessory atrioventricular [AV] pathway of the fast type, three with a concealed accessory AV pathway of the slow type and one with a nodo-ventricular accessory pathway). Three patients had incessant atrial tachycardia, one of whom also had the Wolff-Parkinson-White syndrome. Intravenous encainide (1.5 mg/kg in 15 minutes) terminated incessant supraventricular tachycardia in seven of nine patients. In four of nine patients, supraventricular tachycardia could thereafter still be reinitiated by pacing. Oral encainide (100 to 325 mg/day, mean 180) completely suppressed the incessant supraventricular tachycardia in eight patients in a follow-up period of 5 to 20 months (mean 11). In two patients, episodes of tachycardia were markedly reduced with the administration of encainide in combination with sotalol (one patient) and amiodarone (one patient). Encainide failed to control incessant tachycardia in one patient. Mild central nervous system side effects developed in two patients, but both could continue taking oral encainide. Encainide proved to be a very useful agent to control incessant supraventricular tachycardia resistant to other antiarrhythmic agents.

Administration, Oral↗
PubMed1984

Ventricular tachycardia with alternate ventriculo-atrial Wenckebach conduction due to two-level block.

A 54-year-old patient was studied because of ventricular tachycardia following an inferior myocardial infarction. During one episode of non-sustained ventricular tachycardia a 9:4 alternating ventriculo-atrial Wenckebach block was noted. This was based upon a 2:1 block between the ventricles and the bundle of His and a 5:4 Wenckebach block between the bundle of His and the atria. Our study shows that alternate Wenckebach periods during ventriculo-atrial conduction may be caused by two or more levels of block in the ventriculo-atrial conduction system.

Cardiac Pacing, Artificial↗
PubMed1984

A comparison of the electrophysiologic effects of intravenous and oral amiodarone in the same patient.

In 12 patients (nine with Wolff-Parkinson-White syndrome and three with ventricular tachycardia) the electrophysiologic effects of intravenous (5 mg/kg body weight in 1 min) and oral (total dose 9800 to 11,200 mg) amiodarone were studied with programmed stimulation of the heart. Intravenous and oral amiodarone had a similar (p less than .05) effect of lengthening on the effective refractory period of the atrioventricular node. Only intravenous amiodarone prolonged (p less than .05) the AH interval. Oral amiodarone was more effective than intravenous amiodarone in lengthening the anterograde effective refractory period of the accessory atrioventricular pathway. Only oral amiodarone prolonged the effective refractory period of atrium and ventricle and the HV interval, all significantly (p less than .05). Intravenous amiodarone slowed (p less than .05) the rate of circus-movement tachycardia in patients with Wolff-Parkinson-White syndrome, and further slowing was observed after oral amiodarone. Termination of tachycardia by intravenous amiodarone predicted prevention of reinitiation of tachycardia during oral amiodarone. These data indicate that intravenous and oral amiodarone do not have the same electrophysiologic effects. It is not clear whether cumulative effects, active metabolites, or both are responsible for these differences.

Administration, Oral↗
PubMed1984

Significance of ventricular arrhythmias initiated by programmed ventricular stimulation: the importance of the type of ventricular arrhythmia induced and the number of premature stimuli required.

An increasing number of premature ventricular stimuli are being used during programmed stimulation of the heart in the investigation of patients with documented or suspected ventricular arrhythmias. To analyze the significance of the different types of ventricular arrhythmias that are initiated, we evaluated in a prospective study the effect of from one to four ventricular premature stimuli in 52 patients without (non-VT group) and 50 patients with (prior-VT group) documented ventricular tachycardia or ventricular fibrillation. More than half of the patients in the prior-VT group had coronary heart disease. In the majority of patients of the non-VT group the heart was normal. In 44 of the 50 patients in the prior-VT group the clinically documented ventricular arrhythmia was initiated by programmed ventricular stimulation of the heart. In 88% of these 44 patients, one or two ventricular premature beats were required to initiate the clinical arrhythmia. A ventricular arrhythmia could be initiated in 31 of the 52 patients in the non-VT group. The ventricular arrhythmias included nonsustained monomorphic ventricular tachycardia (two patients), six to 25 complexes of sustained polymorphic ventricular tachycardia (24 patients), and ventricular fibrillation (five patients). In 70% of patients in the non-VT group three or four ventricular premature beats were required to initiate the ventricular arrhythmia. Our results indicate that not only the number of extrastimuli required to initiate ventricular arrhythmias but also the type of ventricular arrhythmia initiated differed between the two groups of patients. Nonsustained polymorphic ventricular tachycardia and ventricular fibrillation are nonspecific responses to aggressive stimulation protocols.

Adolescent↗
PubMed1983

Results of a ventricular stimulation protocol using a maximum of 4 premature stimuli in patients without documented or suspected ventricular arrhythmias.

A prospective study was undertaken to assess the results of an aggressive ventricular stimulation protocol in 52 nonmedicated patients without a documented or suspected ventricular arrhythmia (VA). Thirty-five patients had no structural heart disease, 8 coronary artery disease, 6 hypertrophic cardiomyopathy, 2 mitral valve disease and 1 patient had congestive cardiomyopathy. The patients were 12 to 72 years old. One to 4 ventricular premature beats (twice diastolic threshold, 2 ms in duration) were given during sinus rhythm and during ventricular pacing at 100 beats/min at the right ventricular apex. End points were initiation of 6 or more beats of VA or every extrastimulus brought to its refractory period. In 31 of 52 patients (60%), a VA was initiated (nonsustained polymorphic ventricular tachycardia in 24 patients, nonsustained monomorphic ventricular tachycardia in 2 and ventricular fibrillation requiring countershock in 5). Repetitive ventricular responses (RVR) (1 to 5 beats) were initiated in 46 patients. In 15 patients only RVRs were initiated. In 6 patients RVRs or VA were not initiated. At the end of the follow-up period (mean 14 months), no patient had spontaneous VA and all were alive. This study shows that ventricular stimulation can result in initiation of VA in patients without clinical VA. Interpretation of results of programmed ventricular stimulation in patients without clinically documented VA should be made with caution.

Adolescent↗
PubMed1983

Effect of amiodarone in paroxysmal supraventricular tachycardia with or without Wolff-Parkinson-White syndrome.

In Wolff-Parkinson-White (WPW) syndrome, the two most commonly occurring arrhythmias are circus movement tachycardia (CMT) and atrial fibrillation (AF). In 70% of patients with clinically documented CMT in whom the arrhythmia could be initiated by programmed electrical stimulation of the heart, the same CMT could still be initiated after long-term oral amiodarone administration. Spontaneous clinical recurrence of the arrhythmia was, however, observed in only 10% of patients. This finding suggests that the beneficial effect of amiodarone on CMT is primarily based on the prevention of the CMT-initiating premature beat. This may also apply to atrioventricular nodal reentrant tachycardia, in which amiodarone is also extremely effective in preventing relapses. The role of amiodarone in other forms of reentrant, or ectopic, supraventricular tachycardias is less well defined. During AF in WPW syndrome, the ventricular rate is related to the duration of the anterograde refractory period of the accessory pathway. Amiodarone prolongs this value, resulting in the reduction of ventricular rate during AF. Unfortunately, in the presence of a short anterograde refractory period of the accessory pathway, amiodarone results in only a small amount of lengthening of this value. In these patients the beneficial effect of amiodarone may primarily be related to the prevention of episodes of AF. We also found that the effect of oral amiodarone on the duration of the anterograde refractory period of the accessory pathway can (1) be abolished by sympathetic stimulation with isoproterenol and (2) be predicted from the effect of ajmaline or procainamide given intravenously. These observations clearly have practical clinical implications.

Ajmaline↗
PubMed1983

Identical QRS complexes during atrial fibrillation with aberrant conduction and ventricular tachycardia. The value of a His bundle recording.

In a patient with chronic congestive heart failure, right bundle branch block-shaped QRS complexes occurred in salvos during atrial fibrillation. The site of origin of these complexes could not be determined from the 12-lead ECG alone. Recording of a His bundle electrogram showed that both intraventricular aberrant conduction and ventricular tachycardia were responsible for salvos having the same QRS complexes in the 12-lead ECG.

Aged↗
PubMed1983

Value of QRS alteration in determining the site of origin of narrow QRS supraventricular tachycardia.

To determine the value of alternation of QRS morphology in determining the site of origin of sustained narrow QRS supraventricular tachycardia (SVT), we retrospectively studied 163 distinct tachycardias in 161 patients (ages 4 to 91 years) in whom the site of origin of SVT was proven by intracardiac electrophysiologic study. Sustained SVT was defined as lasting longer than 30 sec. Narrow QRS was defined as QRS width less than 0.12 sec. Atrial fibrillation and flutter were excluded. The presence or absence of QRS alternation was judged at least 10 sec after initiation of SVT. Circus movement tachycardia with anterograde AV node conduction and a retrograde accessory AV pathway was seen in 89 patients (58 with Wolff-Parkinson-White syndrome, 31 with concealed accessory pathway); intra-AV nodal reentrant tachycardia (AVNT) was present in 57 cases, and 17 tachycardias were atrial in origin. QRS alternation was present in 36 of 163 cases (22%). In only eight of these 36 did RR interval length alternation accompany alternation in QRS morphology. Thirty-three of 36 (92%) tachycardias with QRS alternation were circus movement tachycardias. Two were atrial in origin and one was AVNT. We conclude that the presence of QRS alternation during sustained narrow QRS SVT is highly indicative of a retrograde accessory AV pathway in the tachycardia circuit.

Adolescent↗
PubMedDate not supplied

Disposition of amiodarone and its proximate metabolite, desethylamiodarone, in the dog for oral administration of single-dose and short-term drug regimens.

A comparative study of the plasma disposition and tissue distribution of amiodarone and its proximate metabolite, desethylamiodarone, for a single oral dose and short-term oral dosage regimens was conducted in the dog. Four groups of male mongrel dogs (six per group) received one of the following oral dosage regimens: single dose of 40 mg amiodarone/kg; 40 mg amiodarone/kg/day for 10 days and then 30 mg/kg/day for 4 days; 40 mg amiodarone/kg/day for 10 days, 30 mg/kg/day for 4 days, and then no treatment for 14 days; and 40 mg amiodarone/kg/day for 10 days, 30 mg/kg/day for 4 days, and then 20 mg/kg/day for 5 days/week for 2 weeks. The plasma and tissue amiodarone and desethylamiodarone concentrations were determined by HPLC. The plasma concentration of amiodarone was greater than that of desethylamiodarone for the four dosage regimens. The apparent plasma elimination half-life of amiodarone was prolonged following repeated drug administration (3.2 days) compared with a single drug dose (7.5 hr). There was extensive extravascular distribution of amiodarone and desethylamiodarone resulting in progressive tissue accumulation of drug and metabolite for the short-term regimens. For most of the dosage regimens, the concentration of amiodarone was greater than that of desethylamiodarone in left and right ventricles, thyroid gland, adipose tissue, and kidney, whereas the parent drug and metabolite concentrations were similar in lung, liver, and brain. There was predominant accumulation of amiodarone in adipose tissue and desethylamiodarone in lung. After cessation of amiodarone administration, there was rapid elimination of parent drug and metabolite from all tissues, except for amiodarone from adipose tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMedDate not supplied

Ethacrynic acid: acute hemodynamic effects and influence on the in vivo and in vitro response to nitroglycerin in the dog.

We examined the hemodynamic effect of ethacrynic acid (EA), a diuretic, and sulfhydryl binding reagent in the dog to determine whether EA attenuated the response to nitroglycerin (GTN) in vivo or in vitro in rings of dorsal pedal artery (DPA). Six dogs (group A) received infusions of GTN (21 micrograms/min i.v.) before and after EA (0.75 mg/kg). EA produced a marked diuresis [289 ml +/- 41 (SD) urine during 60 min]; 10 min after EA and before substantial diuresis, there was a transient increase in heart rate (HR) from 117 beats/min +/- 29 to 143 beats/min +/- 28 and in mean arterial pressure (MAP) from 137 mm Hg +/- 18 to 144 mm Hg +/- 17 (p less than 0.005). Intravenous GTN resulted in a similar decline in systolic blood pressure before (14.7% +/- 6.4) and after (9.4% +/- 8.1) EA. We also studied two additional groups of dogs that received either EA (0.75 mg/kg) or saline, and urine output was replaced with saline. Similar results were obtained as with group A. In the in vitro studies, 75 rings of DPA from 14 dogs were pretreated with EA at low (1.6 X 10(-5) M), medium (8.3 X 10(-5) M), or high (1.7 X 10(-4) M) doses or EA solvent (control) for 30 min, and dose-response curves were performed for GTN (10(-9) to 10(-5) M). In control rings, the maximum relaxation achieved with GTN was 89% +/- 5.8 inhibition of phenylephrine-induced tone; with both the medium and high EA doses, the response to GTN was partially attenuated.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

Pharmacokinetic-hemodynamic studies of disopyramide.

The hemodynamic effects and pharmacokinetics of two doses of disopyramide (DP) given as a two-stage intravenous load and maintenance infusion were studied in anesthetized dogs. One group (n = 4) received 4 mg/kg for 30 min and 1 mg/kg/h for 30 min (low-dose group). The high-dose group (n = 4) received 8 mg/kg for 30 min and 4 mg/kg/h for 30 min. In the low-dose group, there was a fall in cardiac output which reached statistical significance at 300 min [from 3.4 +/- 0.4 (SD) to 2.7 +/- 0.7 L/min; p less than 0.05, analysis of variance (ANOVA)]. In the high-dose group, there also was a fall in cardiac output (from 4.6 +/- 1.4 to 3.0 +/- 0.4 L/min; p less than 0.01, ANOVA), and this was associated with a rise in total peripheral resistance (from 39 +/- 11 to 58 +/- 9 units; p less than 0.01). Peak total venous DP concentrations were 3.0 +/- 0.2 and 7.5 +/- 1.0 micrograms/ml for the low- and high-dose groups, respectively, and were achieved at the end of the load infusion. The free fraction of DP was not dependent on total venous DP concentration and approximated 0.66. Elimination half-life, clearance, and apparent volume of distribution were 3.91 +/- 0.53 h, 0.39 +/- 0.02 L/kg/h, and 2.22 +/- 0.32 L/kg, respectively, for the low-dose group and 3.67 +/- 0.91 h, 0.36 +/- 0.06 L/kg/h, and 1.84 +/- 0.29 L/kg, respectively, for the high-dose group. There were no significant differences between these measurements for low- versus high-dose groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗