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Biomedical subjects

J Morganroth

Publications and source records attributed to J Morganroth.

At least 19 recordsLinked to original sources
PubMed1992

Early and late proarrhythmia from antiarrhythmic drug therapy.

Antiarrhythmic drug therapy is used with the hope of suppressing arrhythmias and therefore decreasing their associated symptoms or prolonging life. Unfortunately, many antiarrhythmic drugs have the opposite effect of exacerbating or provoking arrhythmias, a phenomenon that is termed proarrhythmia when such an event is specifically due to the drug in use. Early proarrhythmic events (within 30 days of initiation of drug use) have been reasonably well characterized and are predicted by either type of drug employed or the nature of the patient's cardiac disease and arrhythmia type. Late proarrhythmic events, as defined by placebo-controlled trials, have now been recognized as an increased risk of arrhythmic death in patients on antiarrhythmic drugs after many months of therapy. Initially, this late proarrhythmic event was identified with encainide and flecainide, but now several new studies have demonstrated that the risk of late proarrhythmia of comparable magnitude may be present in patients subjected to commonly used drugs, such as quinidine, mexelitine, etc. At present, only moricizine and the class II drugs (beta-adrenergic blockers) appear not to have this potential late proarrhythmic response. Therefore, before instituting antiarrhythmic drug therapy, the physician must be able to quantitate the degree of proarrhythmia and other risks of such therapy, as compared to their potential benefit, to define the proper indications for these agents.

Anti-Arrhythmia Agents↗
PubMed1992

The relationship of anticoagulation level and complications after successful percutaneous transluminal coronary angioplasty.

The degree of anticoagulation and its effect on the frequency of abrupt coronary artery closure, coronary ischemia, bleeding complications requiring transfusion, and death were examined in 336 patients after elective percutaneous transluminal coronary angioplasty (PTCA). All patients received a bolus of 10,000 U of heparin at the beginning of the procedure followed by a continuous infusion of 2000 U/hr. At the conclusion of the procedure the infusion was reduced to 1000 U/hr and continued for 18 to 24 hours at which time the heparin infusion was suspended to allow removal of arterial and venous access sheaths. Partial thromboplastin time (PTT) was examined while patients continued to receive the heparin infusion. There was a variable degree of PTT prolongation in response to a standard dose of heparin with a range of 34 seconds to "greater than 150 seconds." Patients were divided into two groups according to the degree of heparin-induced PTT prolongation: group A included 271 patients with PTT greater than or equal to 3 times the control value, and group B comprised 65 patients with PTT less than 3 times the control value. Ischemic complications were analyzed on day 1 after PTCA and at hospital discharge. Bleeding complications and mortality were examined only at hospital discharge. There was a significant reduction in the incidence of abrupt coronary artery closure in group A on day 1 (1.5% vs 10.7%, p less than 0.001) and at hospital discharge (2.6% vs 10.7%, p less than 0.003).(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon, Coronary↗
PubMed1992

Proarrhythmic effects of antiarrhythmic drugs: evolving concepts.

Although antiarrhythmic drugs are prescribed to reduce an arrhythmia, they may have the paradoxic effect of actually exacerbating that arrhythmia or causing new or more serious forms. This effect is known as "proarrhythmia." Proarrhythmic events may be segregated into those that occur "early" after therapy (within 30 days) and those that occur "late," after many months of therapy and manifesting as a fatal event (an increased risk of sudden cardiac death). The ability of the physician to predict drug proarrhythmia and its severity depends on the class of antiarrhythmic drug chosen, the type of ventricular arrhythmia to be treated, and the severity of the patient's underlying left ventricular dysfunction. Before the start of antiarrhythmic therapy, the physician must be able to quantitate the degree of proarrhythmic risk so that the benefit/risk ratio of such drug use can be determined.

Anti-Arrhythmia Agents↗
PubMed1992

Drug-induced early and late proarrhythmia.

Proarrhythmia is the provocation of a new arrhythmia or the exacerbation of a spontaneously occurring arrhythmia due to drug therapy. A drug's toxic effect may occur early after its initiation, and specific definitions have been offered to detect its presence. Primary and secondary forms of proarrhythmia as well as the type of early proarrhythmic events (fatal, serious, and nonserious) have been recognized. More recently, the concept of a late proarrhythmic event (enhanced arrhythmic death) has been defined using placebo-controlled trials. This late proarrhythmic response is extremely important in defining the benefit versus risk ratio that is the key to proper use of drug therapy.

Arrhythmias, Cardiac↗
PubMed1991

Effect of angiotensin converting enzyme inhibition on the incidence of restenosis after percutaneous transluminal coronary angioplasty.

To determine whether angiotensin converting enzyme (ACE) inhibition may reduce the incidence of restenosis after percutaneous transluminal coronary angioplasty (PTCA), we retrospectively identified 322 consecutive patients who underwent a successful procedure from June 1988 to December 1989. No patients developed chest pain, ST segment elevation, positive cardiac enzymes, or other evidence of abrupt vessel closure following the PTCA. All patients received intravenous heparin after PTCA and aspirin was begun on the day prior to PTCA. Patients were separated into two groups: those at hospital discharge incidentally treated for hypertension or heart failure with ACE inhibitors (n = 36), and those treated with a drug regimen which did not include ACE inhibitors (n = 286). The two groups were similar with respect to age (61 +/- 13.5 vs. 60 +/- 12.5, p = NS) and other demographic characteristics. Restenosis, defined as the presentation to a physician with symptoms of angina within 6 months of the PTCA and the finding on repeat catheterization of a significant restenosis at the site of the PTCA, occurred in 30% of the patients who were discharged on a drug regimen which did not include ACE inhibitors vs. 3% (p less than .05) in those treated with an ACE inhibitor. Thus, it appears that the use of ACE inhibitors may significantly reduce the incidence of restenosis after successful PTCA.

Aged↗
PubMed1990

Dose effect of moricizine on suppression of ventricular arrhythmias.

To define the pharmacologic properties of moricizine in patients with benign or potentially lethal ventricular arrhythmias, 1,072 patients in the moricizine data base through February 1987 were evaluated. In dose-ranging and titration trials as well as in a cross-study analysis of th entire data base, the minimally effective dose for moricizine was found to be 600 mg/day and the optimal dose range from 600 to 900 mg/day. The dose efficacy relation plateaued beyond 900 mg/day. With use of a 75% reduction in ventricular premature complex frequency as the definition of a drug responder, 391 of 583 patients (67%) with paired Holter monitors demonstrated overall efficacy. The dose onset of moricizine was between 16 and 20 hours and the dose offset was at approximately 24 hours at the point when 50% of the ventricular arrhythmia frequency returned to baseline. Although moricizine was primarily given on a 3-times-a-day regimen during clinical trials, dose interval evaluation suggested that a twice-a-day regimen may produce the same degree of efficacy although there are limited data regarding comparable safety.

Anti-Arrhythmia Agents↗
PubMed1990

Treatment of ventricular arrhythmias by United States cardiologists: a survey before the Cardiac Arrhythmia Suppression Trial results were available.

To define the practice habits of United States cardiologists and the treatment of ventricular arrhythmias, a random sample of 1,000 of 12,000 cardiologists was sent a pretested questionnaire. After follow-up procedures, 252 responded, of which 18% were academically-based, 29% were hospital-based and 53% were office-based. Attitudes about antiarrhythmic drug therapy for the treatment of ventricular arrhythmias were influenced by the presence and severity of cardiac disease, the presence and severity of cardiac disease, the presence of symptoms and the type of ventricular arrhythmias. In this survey, only 1% of cardiologists treated patients with asymptomatic ventricular premature complexes and no heart disease, but 17% treated such patients if unsustained ventricular tachycardia was present. The treatment rate among cardiologists increased to 38% when coronary artery disease with left ventricular dysfunction was present in patients with asymptomatic ventricular premature complexes. The presence of any cardiac disease and symptomatic ventricular arrhythmias increased the treatment rate to 80 to 100%. Approximately 50% of responding physicians treated patients comparable to the Cardiac Arrhythmia Suppression Trial study population with antiarrhythmic drugs. Beta blockers were the most common antiarrhythmic drug class chosen as the most appropriate initial therapy in new patients with ventricular arrhythmias. Whereas no cardiologists thought that amiodarone was appropriate to initiate in new patients with benign or potentially malignant ventricular arrhythmias, as many as 33 to 43% of cardiologists would use amiodarone for refractory patients with such arrhythmias, a response contradictory to the approved labeling for this drug. Less than one half of cardiologists recognize the high potential organ toxicity for quinidine, procainamide and tocainide.(ABSTRACT TRUNCATED AT 250 WORDS)

Anti-Arrhythmia Agents↗
PubMed1979

Ethmozin: a new antiarrhythmic agent developed in the USSR. Efficacy and tolerance.

Ethmozin, a phenothiazine derivative, was developed in the Soviet Union as a new antiarrhythmic agent. We evaluated ethmozin using a controlled single-blinded in-hospital protocol in 14 ambulatory patients with ventricular ectopy ranging from an average of 48 to 1,801 depolarizations per hour and in eight patients with atrial ectopy ranging from 63 to 693 depolarizations per hour. Placebo was administered for the first 3 days, followed by ethmozin from 2.4 to 11.2 mg./Kg./day administered orally every 8 hours for 7 days and concluding with placebo for the final 3 days. Continuous 24-hour long-term electrocardiographic monitoring for 13 days was employed to measure drug efficacy accurately. Six of eight (75 per cent) patients with atrial ectopy and 10 of 14 (71 per cent) patients with ventricular ectopy had statistically significant reductions in ectopy during ethmozin therapy. Atrial ectopy was reduced at a lower dose and plasma level of ethmozin than was ventricular ectopy. With the exception of mild nausea in one patient, no side effects of ethmozin therapy were noted. Ethmozin appears to be a well-tolerated, effective antiarrhythmic agent with a dosage regimen that can promote patient compliance for long-term use.

Adult↗
PubMed1979

Relationship of atrial fibrillatory wave amplitude to left atrial size and etiology of heart disease. An old generalization re-examined.

It is commonly stated that coarse f waves in atrial fibrillation suggest the presence of rheumatic heart disease and large left atrial size, whereas fine f waves indicate non-rheumatic disease and small left atrial size. Using echocardiography as a more reliable indicator of left atrial size, 37 consecutive patients with chronic atrial fibrillation were evaluated. The correlation coefficients between left atrial size and maximum f wave amplitude was -0.12 and -0.07, using average f wave amplitude. Only 53 per cent (9 of 17) of patients with rheumatic heart disease had f wave greater than 1 mm. and 56 per cent (10 of 18) of patients with f wave size less than or equal to 1 mm. had non-rheumatic disease. This study refutes the contention that the f wave amplitude in atrial fibrillation is correlated with either left atrial size or etiology of heart disease. It is possible that an intra-atrial conduction defect is responsible for coarse f wave morphology.

Atrial Fibrillation↗
PubMed1979

Exercise performance after septal myotomy and myectomy in patients with obstructive hypertrophic cardiomyopathy.

The effect of left ventriculomyotomy and myectomy on exercise capacity and cardiac function in patients with obstructive hypertrophic cardiomyopathy has not previously been determined. In this study, 29 patients were evaluated during graded treadmill exercise before and after operation. Postoperatively, 27 of 29 patients reported symptomatic improvement and had greatly reduced left ventricular outflow gradient. Twenty-five of 28 patients (89 percent) attained higher exercise levels after operation, and this was accompanied by an increase in total body oxygen consumption from 16 to 21 ml/min per kg (P less than 0.005). A significant increase in cardiac index during maximal exercise also accompanied this improved exercise performance (5.0 to 5.7 liters/min per m2, P less than 0.05). The increase in maximal cardiac index was associated with greater desaturation of mixed venous blood (34 to 24 percent, P less than 0.02) in patients with preoperative angina. At a given level of mixed venous oxygen saturation (30 percent), overall mean cardiac index was higher postoperatively (4.6 to 5.2 liters/min per m2, P less than 0.05). These results suggest that, although several mechanisms probably contribute to symptomatic improvement after myotomy and myectomy, enhanced cardiac performance plays an important role in the majority of patients.

Adolescent↗
PubMed1979

Discrete fibromembranous aortic stenosis in middle age. Natural history and case report.

Discrete fibromembranous subaortic stenosis may be severe at birth, progress in severity irrespective of the initial degree of obstruction, and morphologically change during the course of its natural history. Initial status, progression of the lesion and perhaps later development of fibromuscular (tunnel) and/or asymmetric septal hypertrophy may all contribute to a shortened life span and account for the different incidence of fibromembranous subaortic stenosis in children and adults. In the case reported here, a patient survived into the sixth decade with a discrete fibromembranous subaortic stenosis, which led to typical as well as unusual echocardiographic findings.

Age Factors↗
PubMed1979

Retinal arteriolar changes as an indicator of coronary artery disease.

Funduscopic examination was performed in 70 non diabetic, nonhypertensive patients without valvular heart disease undergoing coronary angiography for evaluation of chest pain syndromes to determine if retinal arteriolar changes could reliably predict presence of coronary artery disease. Retinal arteriolar changes were graded with respect to light reflex, vessel caliber, arteriovenous crossing defects, and vessel tortuosity without knowledge of angiographic findings. Each coronary vessel was graded with respect to its most occlusive lesion by angiography; coronary index was derived for each patient without knowledge of eye findings. Abnormal light reflex changes were the most sensitive indicators of presence and extent of coronary artery disease. Abnormal vessel tortuosity and decreased caliber were less sensitive but more specific; their presence also suggested more extensive coronary lesions. Thus, funduscopic examination demonstrating specific retinal arteriolar lesions may indicate presence of coronary artery disease and may correlate with extent of lesions in selected patients.

Adult↗
PubMed1978

Fascicular conduction distrubances after coronary bypass surgery.

Two hundred patients underogoing coronary bypass graft surgery were studied to determine the frequency and significance fo new fascicular conduction distrubances. The follow-up period ranged from 13 to 39 months. New disturbances developed in 39 patients (20 percent). Isolated right bundle branch block (6 percent) and left anterior hemiblock (6 percent) were the most common disturbances. Righ bundle branch block was usually transient and was not associated with further complications in the follow-up period. However, patients with either transient or persistent left bundle branch block or left anterior hemiblock, or both, had (1) increased later mortality compared with patients without new fascicular conduction disturbances (5 of 26 versus 11 of 161; P less than 0.02), and (2) increased late myocardial infarction (2 of 26 versus 2 of 161; P less than 0.05). New left fascicular conduction disturbances after coronary surgery identified a subset of patients with more extensive ischemic heart disease, suggesting that these patients require close follow-up care.

Adult↗
PubMed1978

Apex sector echocardiography in evaluation of the right atrium in patients with mitral stenosis and atrial septal defect.

Cross-sectional echocardiography utilizing the four chamber apical view was used to evaluate right atrial dimensions as a means of detecting abnormal right heart hemodynamics in 20 patients with mitral stenosis, 5 patients with an atrial septal defect and 10 patients without heart disease. Right and left atrial dimensions on apex echocardiography were 40 mm or less in control subjects. There was a good correlation (r = 0.81) between left atrial size assessed with apex sector and M mode echocardiography. In patients with an atrial septal defect, the left atrium was of normal size on apex sector echocardiography; in patients with mitral stenosis, it was larger on apex echocardiography (59 +/- 9 mm) than on M mode echocardiography (51 +/- 8 mm). The right atrium was enlarged (54 +/- 5 mm) on apex echocardiography in all five patients with an atrial septal defect, but the right ventricle was enlarged in only four. Seventeen of 20 patients with mitral stenosis had an enlarged right atrium (53 +/- 7 mm) on apex echocardiography, whereas 15 had normal right ventricular dimensions (21 +/- 9 mm) on M mode echocardiography. Right atrial size on apex echocardiography was enlarged (54 +/- 6 mm) in 10 of 11 patients with mitral stenosis and pulmonary arterial hypertension. Thus, evaluation of the right atrial dimension with apex echocardiography may be more sensitive than M mode echocardiography in detecting early right heart involvement in specific cardiac conditions.

Adult↗