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Biomedical subjects

B McGovern

Publications and source records attributed to B McGovern.

At least 19 recordsLinked to original sources
PubMed2001

Increasing mortality due to end-stage liver disease in patients with human immunodeficiency virus infection.

Highly active antiretroviral therapy has decreased human immunodeficiency virus (HIV)-associated mortality; other comorbidities, such as chronic liver disease, are assuming greater importance. We retrospectively examined the causes of death of HIV-seropositive patients at our institution in 1991, 1996, and 1998-1999. In 1998-1999, 11 (50%) of 22 deaths were due to end-stage liver disease, compared with 3 (11.5%) of 26 in 1991 and 5 (13.9%) of 36 in 1996 (P=.003). In 1998-1999, 55% of patients had nondetectable plasma HIV RNA levels and/or CD4 cell counts of >200 cells/mm(3) within the year before death. Most of the patients that were tested had detectable antibodies to hepatitis C virus (75% of patients who died in 1991, 57.7% who died in 1996, and 93.8% who died in 1998-1999; P=NS). In 1998-1999, 7 patients (31.8%) discontinued antiretroviral therapy because of hepatotoxicity, compared with 0 in 1991 and 2 (5.6%) in 1996. End-stage liver disease is now the leading cause of death in our hospitalized HIV-seropositive population.

Adult↗
PubMed2001

Acute respiratory distress syndrome complicating Plasmodium vivax malaria.

Malaria is one of the most common infectious diseases in the world, and severe respiratory complications have been described mainly in association with Plasmodium falciparum. We describe a case of acute respiratory distress syndrome complicating infection with P. vivax in the setting of relatively low parasitemia in a 47-yr-old woman after a brief trip to Papua New Guinea. A review of the literature shows that pulmonary complications of P. vivax are rare but occur more frequently than generally acknowledged. Pathogenic mechanisms of these complications are discussed.

Antimalarials↗
PubMed1998

Antiarrhythmic drug therapy in pregnancy and lactation.

Antiarrhythmic agents commonly used in clinical practice are reviewed with respect to their potential for teratogenic or other adverse fetal effects. Although most experience with antiarrhythmic drug therapy during pregnancy has accrued with digoxin, quinidine, and propranolol, other antiarrhythmic agents may also be used in the pregnant patient if indicated. The choice of antiarrhythmic drug depends on the specific arrhythmia being treated, the cardiac condition of the patient or fetus, and the known or anticipated actions of the antiarrhythmic drug being considered. The management of specific arrhythmias encountered in pregnant women are also discussed. For benign arrhythmias, a conservative approach starting first with preventive measures is appropriate. For more severe or symptomatic arrhythmias, pharmacologic therapy should be instituted using drugs with proven safety to the fetus, if possible. Electrical cardioversion of the patient may be performed with relative safety in more emergent situations.

Anti-Arrhythmia Agents↗
PubMed1997

Reproducible induction of "atypical" torsades de pointes by programmed electrical stimulation: a novel form of sotalol-induced proarrhythmia?

We present a patient with sotalol-induced polymorphic ventricular tachycardia that was seen only with programmed ventricular stimulation. Electrophysiologic studies performed prior to initiation of sotalol therapy revealed inducible monomorphic ventricular tachycardia. Possible underlying electrophysiologic mechanisms are discussed.

Anti-Arrhythmia Agents↗
PubMed1995

Limitations and late complications of third-generation automatic cardioverter-defibrillators.

BACKGROUND: This study examines the limitations and complex management problems associated with the use of tiered-therapy, implantable cardioverter-defibrillators (ICDs). METHODS AND RESULTS: The study group comprises the first 154 patients undergoing implantation of tiered-therapy ICDs at our institution. Pulse generators from three different manufacturers were used. In 39 patients, a complete nonthoracotomy lead system was used. The perioperative mortality was 1.3%. Of these 154 patients, 37% experienced late postoperative problems. Twenty-one patients required system revision within 36.5 months (mean, 8.57 +/- 11.3) of surgery. Reasons for revision were spurious shocks due to electrode fractures (3) or electrode adapter malfunction (2), inadequate signal from endocardial rate-sensing electrodes (3), superior vena cava or right ventricular coil migration (5), failure to correct tachyarrhythmias due to a postimplant rise in defibrillation threshold (5), or pulse generator failure (3). One of these patients required system removal for infection after revision of an endocardial lead. A further 32 patients received inappropriate shocks for atrial fibrillation with a rapid ventricular response or sinus tachycardia. Two of these patients also received shocks for ventricular tachycardia initiated by antitachycardia pacing triggered by atrial fibrillation. Ventricular pacing for bradycardia was associated with inappropriate shocks due to excessive autogain in 2 patients. CONCLUSIONS: Despite the major diagnostic and therapeutic advantages of tiered-therapy ICDs, a significant proportion of patients continue to experience hardware-related complications or receive inappropriate shocks.

Algorithms↗
PubMed1991

Structure activity hypotheses in occupational asthma caused by low molecular weight substances.

Many substances with a low molecular weight (less than 1000 molecular weight) but of different chemical classes are recognized as causative agents of occupational asthma. Some of their major chemical properties are highlighted in relation to their putative interactions with human macromolecules. Thus, certain transition metals which form co-ordination complexes may chelate human proteins. Several organic substances have marked basic properties which are responsible for their chemical reactivity. Some of these, such as the bifunctional bases ethylene diamine, piperazine and para-phenylene diamine are known causative agents of asthma while their monofunctional counterparts, in spite of wide industrial application, are not similarly recognized causes. This suggests that the presence of multiple reactive groups is of importance in the molecular interactions with human macromolecules that eventually lead to occupational asthma. Reference is also made to other substances to exemplify hypothetical mechanisms of these interactions. Such generation of hypotheses is a prelude to quantitative studies of structure activity relationships (QSARs) where the hypotheses can be tested and revised. Structure activity hypotheses in isolation might not be adequate predictors of the risk of occupational asthma. However, if applied to novel chemical entities they might eventually prove useful in contributing to the development of policies for prospective health surveillance and in establishing priorities for epidemiological research.

Air Pollutants, Occupational↗
PubMed1990

Adenosine for paroxysmal supraventricular tachycardia: dose ranging and comparison with verapamil. Assessment in placebo-controlled, multicenter trials. The Adenosine for PSVT Study Group.

OBJECTIVE: To assess the safety and efficacy of intravenous adenosine in terminating acute episodes of paroxysmal supraventricular tachycardia. DESIGN: Two prospective, double-blind, randomized, placebo-controlled trials to evaluate dose response in patients receiving adenosine and to compare the effects of adenosine with those of verapamil. PATIENTS: A total of 359 patients with a tachycardia electrocardiographically consistent with paroxysmal supraventricular tachycardia were entered into the two protocols. Patients subsequently found to have arrhythmias other than paroxysmal supraventricular tachycardia were excluded from the efficacy analysis. INTERVENTIONS: The first protocol compared sequential intravenous bolus doses of 3, 6, 9, and 12 mg of adenosine to equal volumes of saline. In the second protocol, patients received either 6 mg and, if necessary, 12 mg of adenosine or 5 mg and, if necessary, 7.5 mg of verapamil. MEASUREMENTS AND MAIN RESULTS: When data are expressed in terms of cumulative response in eligible patients, intravenous adenosine terminated acute episodes of paroxysmal supraventricular tachycardia in 35.2%, 62.3%, 80.2%, and 91.4% of patients who received maximum doses of 3, 6, 9, and 12 mg, respectively, in a four-dose sequence, whereas 8.9%, 10.7%, 14.3%, and 16.1% of patients responded to four sequential placebo doses (P less than 0.0001). In the second trial, cumulative response rates after 6 mg followed, if necessary, by 12 mg of adenosine were 57.4% and 93.4%, and after 5 mg followed, if necessary, by 7.5 mg of verapamil were 81.3% and 91.4%. The average time after injection to termination of tachycardia by adenosine was 30 seconds. Adenosine caused adverse effects in 36% of patients, but they lasted less than 1 minute and were usually mild. CONCLUSIONS: Adenosine in graded doses up to 12 mg rapidly and effectively terminates acute episodes of paroxysmal supraventricular tachycardia in which the atrioventricular node is an integral part of the re-entrant circuit. The overall efficacy of adenosine is similar to that of verapamil, but its onset of action is more rapid. Adverse reactions to adenosine are common but are minor and brief.

Acute Disease↗
PubMed1990

Exercise electrophysiology testing: the effect of exercise on the induction of ventricular arrhythmias by programmed ventricular stimulation.

In order to assess the effect of acute, reversible myocardial ischemia on the outcome of programmed ventricular stimulation (PVS), ventricular stimulation was performed at rest, during exercise, and during recovery in 10 patients with coronary artery disease. Of these ten patients, four were tested while off antiarrhythmic drugs and six were tested on antiarrhythmic drug therapy. Nine of the ten patients developed acute myocardial ischemia during exercise PVS. However, in only two of these ten patients ventricular arrhythmia could be induced by PVS, one during exercise and one during recovery.

Aged↗
PubMed1990

An analysis of the cost effectiveness of the implantable defibrillator.

The automatic implantable defibrillator has been shown to decrease the mortality of patients who have survived cardiac arrest due to ventricular tachycardia or fibrillation and are at high risk for recurrence. We performed a cost-effectiveness analysis of this seemingly expensive new technology with data obtained from the 1984 Medicare data base, the medical literature, Medicare carriers, individual pharmacies and hospitals, and expert opinion. Analyzing combinations of principal and secondary discharge diagnoses across 18 diagnosis-related groups, we estimated the cost of hospitalization for a comparison group of patients. Hospitalization costs for the defibrillator group were obtained from reported empirical data. Rehospitalization rates and other health-care use estimates were solicited from an expert panel of physicians, and mortality rates for both groups were obtained from the literature. Using a decision-analytic model, we estimated that the net cost effectiveness of the defibrillator, when used in the high-risk patient, is approximately $17,100 per life-year saved, with sensitivity analyses suggesting that the true value lies between $15,000 and $25,000. This estimate is well within the range that is currently accepted by the US medical care system for other life-saving interventions. We also estimated the cost effectiveness of the defibrillator in a 1991 scenario to be $7,400 per life-year saved, when the device would have greater longevity, would be programmable, and would not require a thoracotomy. Sensitivity analyses suggest that the true value lies between a value that is cost saving (less expensive than pharmacologic therapy) and $19,600 per life-year saved.

Arrhythmias, Cardiac↗
PubMed1988

Out-of-hospital cardiac arrest. Use of electrophysiologic testing in the prediction of long-term outcome.

We examined the role of electrophysiologic testing in the prediction of long-term outcome in 166 survivors of out-of-hospital cardiac arrest not associated with acute myocardial infarction. Ventricular arrhythmias were inducible in 131 patients (79 percent) at base line and were suppressed by antiarrhythmic drugs or surgery (or both) in 91 of 127 (72 percent). During a median follow-up period of 21 months, cardiac arrest recurred in 29 patients: 11 (12 percent) of the 91 in whom inducible arrhythmias had been suppressed (including 5 patients in whom treatment had been discontinued), 12 (33 percent) of the 36 in whom inducible arrhythmias persisted, and 6 (17 percent) of the 35 in whom arrhythmias could not be induced at the initial electrophysiologic study. Cox survival analysis identified the following three variables as significant independent predictors of recurrent cardiac arrest: persistence of inducible ventricular arrhythmias (relative risk, 3.97 [95 percent confidence interval, 1.80 to 8.75], P = 0.0006), a left ventricular ejection fraction of 30 percent or less (relative risk, 2.60 [1.21 to 5.53], P = 0.0138), and the absence of cardiac surgery (relative risk, 4.20 [0.99 to 17.77], P = 0.0512). We conclude that electrophysiologic testing is useful in quantifying the subsequent risk of cardiac arrest among survivors of out-of-hospital cardiac arrest.

Anti-Arrhythmia Agents↗
PubMed1988

Long-term efficacy of mexiletine alone and in combination with class Ia antiarrhythmic drugs for refractory ventricular arrhythmias.

The efficacy of mexiletine used alone, and in combination with a class Ia antiarrhythmic drug, was assessed in 159 previously drug-refractory patients with ventricular tachycardia (VT) during serial electrophysiologic studies and during long-term (5-year) clinical follow-up. Electrically-inducible ventricular tachycardia was suppressed by mexiletine alone in 23% of patients tested, and a combined antiarrhythmic drug regimen was effective in 29% of the trials performed. Mexiletine was much more likely to be effective in patients presenting with nonsustained VT or ventricular fibrillation than in patients with sustained VT (p less than 0.005). After 1 and 4 years of treatment, 18% and 42% of the patients treated with mexiletine alone had died suddenly or suffered recurrent symptomatic VT, compared to 11% and 25% of patients treated with the combined antiarrhythmic drug regimens (p = NS). Mexiletine therapy was associated with frequent, though readily reversible, adverse reactions. However, mexiletine treatment had to be discontinued permanently in 8 of 92 patients (9%) because of intolerable side effects. We conclude that the added efficacy and possible improved arrhythmia-free survival associated with combining mexiletine with a class Ia agent should be further investigated.

Anti-Arrhythmia Agents↗
PubMed1987

Electrophysiologic effects of d-sotalol in humans.

Sotalol is a beta-adrenergic blocking agent that prolongs the duration of the cardiac action potential in humans, without affecting the upstroke velocity of depolarization. The dextrorotatory isomer, d-sotalol, retains these class III effects, but has little beta-blocking activity in vitro. d-Sotalol has not been studied extensively in humans. The electrocardiographic (ECG) and electrophysiologic effects of d- and d,l-sotalol were therefore assessed in a prospective randomized study of 20 patients. Each patient received either d-sotalol (1, 1.5 or 2 mg/kg body weight) or d,l-sotalol (1 mg/kg) by intravenous infusion. The QT and QTc intervals were prolonged and refractoriness increased in the atrium, atrioventricular (AV) node, His-Purkinje system and right ventricle after both d- and d,l-sotalol. After d-sotalol, the increases in both QT and QTc intervals and in atrial and ventricular effective refractory periods were dose dependent. Highly significant linear correlation was demonstrated between the plasma sotalol level and the change in QT (r = 0.86, p = 0.001) and QTc intervals (r = 0.79, p = 0.002), and between the plasma sotalol level and the effective refractory period of the right atrium (r = 0.75, p = 0.005) and ventricle (r = 0.70, p = 0.025). This study confirms that d-sotalol has effects consistent with class III properties. It demonstrates these effects in humans, and suggests that d-sotalol may prove to be a useful antiarrhythmic agent.

Adolescent↗
PubMed1986

Management of refractory supraventricular tachyarrhythmias using low-energy transcatheter shocks.

Alteration of atrioventricular (AV) conduction was attempted in 7 consecutive patients with severely symptomatic, drug-refractory supraventricular tachyarrhythmias using low-energy, direct-current transcatheter shocks of between 20 and 50 J. A single shock of 50 J or less delivered at the AV junction resulted immediately in complete AV block in 6 of the patients. Complete AV block has persisted in 3 patients, and in another who received a second shock 24 hours after the first. AV conduction was altered in the 3 patients in whom conduction either persisted or returned in such a way that supraventricular arrhythmias no longer occurred or were associated with a much slower ventricular response. After a follow-up of 20 to 37 months (mean 27 +/- 8), all 7 patients have improved symptomatically and 6 are taking no antiarrhythmic drugs. Thus, single low-energy transcatheter shocks can be used to ablate AV conduction. Such shocks may also modify AV conduction without production of complete AV block, but with changes in anterograde or retrograde conduction that may favorably influence recurrent symptomatic supraventricular tachyarrhythmias.

Aged↗
PubMed1986

Reproducibility of ventricular tachycardia suppression by antiarrhythmic drug therapy during serial electrophysiologic testing in coronary artery disease.

The short-term reproducibility of pharmacologic suppression of ventricular tachycardia (VT) induced by programmed cardiac stimulation was tested in patients with coronary artery disease presenting with documented recurrent VT or ventricular fibrillation. Sixty-three consecutive patients in whom sustained VT (30 patients) or nonsustained VT (33 patients) was induced by programmed cardiac stimulation without antiarrhythmic drug treatment, and in whom at least 1 oral antiarrhythmic drug regimen suppressed the induced VT during serial electrophysiologic testing, were entered into the study. Programmed cardiac stimulation was repeated after a mean of 37 +/- 14 hours during the same antiarrhythmic drug regimen. No VT was induced in 59 of the 63 patients during the second study, resulting in a rate of 94% for short-term reproducibility of pharmacologic suppression of induced VT. Of the remaining 4 patients, programmed cardiac stimulation during the second drug study induced sustained VT in 1 patient and nonsustained VT in 3 patients. There was no significant difference in mean right ventricular effective refractory period and QT interval between the first and second drug study. Thus, in this selected population of patients, pharmacologic suppression of electrically induced VT is a reproducible phenomenon.

Aged↗
PubMed1986

Influence of drive cycle length during programmed stimulation on induction of ventricular arrhythmias: analysis of 403 patients.

The drive cycle length at which programmed ventricular stimulation is performed is a fundamental variable in all stimulation protocols, but the influence of this variable on the ability to induce ventricular arrhythmias has not been systematically analyzed. This study, which included 403 patients with prior ventricular tachycardia (VT) or ventricular fibrillation undergoing programmed ventricular stimulation with a uniform protocol that incorporated 3 basic drive cycle lengths from the right ventricular apex, was performed to examine the influence of drive cycle length on the induction of ventricular arrhythmias. The sensitivity of the protocol was 62% for nonsustained VT, 73% for ventricular fibrillation and 89% for sustained VT. Fifty-four percent (217 patients) had an arrhythmia induced with programmed ventricular stimulation during ventricular pacing. No arrhythmia was induced in 96 patients (24%), whereas induction was accomplished during sinus rhythm in 61 patients (15%) and rapid ventricular pacing in 29 patients (7%). With this protocol, the sensitivity for single and double extrastimuli during ventricular pacing increases using decremental drive cycle lengths. Although only 2 patients had induction of a ventricular arrhythmia at a drive cycle length of 700 to 650 ms using a single extrastimulus, 14, 8 and 3 patients had ventricular arrhythmias induced by single extrastimuli at drive cycle lengths of 600 to 550, 500 to 450 and 400 ms, respectively. Of 163 patients with arrhythmias induced with double extrastimuli, only 6 had an arrhythmia induced at drive cycle lengths of 700 to 650 ms.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1986

Perioperative and long-term results after electrophysiologically directed ventricular surgery for recurrent ventricular tachycardia.

Thirty-six patients underwent ventricular aneurysmectomy and electrophysiologically directed endocardial resection for treatment of recurrent ventricular tachycardia refractory to antiarrhythmic drug therapy. The surgical mortality rate was 17% and all 30 patients discharged from the hospital were alive at the end of the follow-up period (range 6 to 54 months), yielding a cumulative projected survival rate of 83% by actuarial analysis. Poor systolic function of the nonaneurysmal ventricular segments was the strongest and the only independent predictor of operative mortality among the clinical, hemodynamic, angiographic and electrophysiologic variables analyzed by stepwise logistic regression. Ventricular tachycardia recurred early in four of the six patients in whom the endocardial resection was limited to a small area for technical reasons. Twelve patients, including 10 with sustained ventricular tachycardia still inducible by postsurgical programmed electrical stimulation, were discharged receiving antiarrhythmic drugs that had been tried unsuccessfully before surgery. During a mean follow-up period of 25 +/- 15 months, nonfatal sustained ventricular tachycardia recurred in two patients after discharge. Inadequate endocardial resection was a significant predictor of arrhythmia recurrence.

Actuarial Analysis↗
PubMed1986

Ventricular tachycardia: historical perspective.

Ventricular tachycardia is now diagnosed frequently in patients with organic heart disease. Although ventricular tachycardia was first demonstrated electrocardiographically 75 years ago, the natural history, fundamental mechanisms, and optimal management have remained elusive. Early observers commented on the rarity of occurrence and poor prognosis associated with this arrhythmia, yet with time, some patients with ventricular tachycardia were reported to survive for prolonged periods. Because of the sporadic nature of the arrhythmia and its variable prognosis, assessment of the efficacy of therapies has been difficult. A wide variety of treatments has been advocated with enthusiasm, but only a few have been consistently reported to be effective. Citation of historical data to claim benefit from new treatments should be viewed with caution.

Cardiac Pacing, Artificial↗