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Biomedical subjects

F I Marcus

Publications and source records attributed to F I Marcus.

At least 19 recordsLinked to original sources
PubMed2001

Baroreflex sensitivity and heart rate variability in the identification of patients at risk for life-threatening arrhythmias: implications for clinical trials.

BACKGROUND: The need for accurate risk stratification is heightened by the expanding indications for the implantable cardioverter defibrillator. The Multicenter Automatic Defibrillator Implantation Trial (MADIT) focused interest on patients with both depressed left ventricular ejection fraction (LVEF) and the presence of nonsustained ventricular tachycardia (NSVT). Meanwhile, the prospective study Autonomic Tone and Reflexes After Myocardial Infarctio (ATRAMI) demonstrated that markers of reduced vagal activity, such as depressed baroreflex sensitivity (BRS) an heart rate variability (HRV), are strong predictors of cardiac mortality after myocardial infarction. METHODS AND RESULTS: We analyzed 1071 ATRAMI patients after myocardial infarction who had data on LVEF, 24-hour ECG recording, and BRS. During follow-up (21 +/- 8 months), 43 patients experienced cardiac death, 5 patients had episodes of sustained VT, and 30 patients experienced sudden death and/or sustained VT. NSVT, depressed BRS, or HRV were all significantly and independently associated with increased mortality. The combination of all 3 risk factor increased the risk of death by 22x. Among patients with LVEF<35%, despite the absence of NSVT, depressed BRS predicted higher mortality (18% versus 4.6%, P = 0.01). This is a clinically important finding because this grou constitutes 25% of all patients with depressed LVEF. For both cardiac and arrhythmic mortality, the sensitivity of lo BRS was higher than that of NSVT and HRV CONCLUSIONS: BRS and HRV contribute importantly and additionally to risk stratification. Particularly when LVEF is depressed, the analysis of BRS identifies a large number of patients at high risk for cardiac and arrhythmic mortalit who might benefit from implantable cardioverter defibrillator therapy without disproportionately increasing the number of false-positives.

Arrhythmias, Cardiac↗
PubMed2001

Familial Mahaim syndrome.

We describe the occurrence of Mahaim syndrome in a mother and her son. The occurrence of such a rare disorder in two members of a family is noteworthy, has not been reported before, and suggests the possibility of genetic transmission. A genetic transmission of supraventricular tachycardia has been described only in rare cases for the Wolff-Parkinson-White syndrome. No such data is available for the Mahaim syndrome.

Adult↗
PubMed2000

Arrhythmogenic right ventricular dysplasia/cardiomyopathy: need for an international registry. Study Group on Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy of the Working Groups on Myocardial and Pericardial Disease and Arrhythmias of the European Society of Cardiology and of the Scientific Council on Cardiomyopathies of the World Heart Federation.

Arrhythmogenic right ventricular (RV) dysplasia/cardiomyopathy (ARVD/C) is a heart muscle disease characterized by peculiar RV involvement and electrical instability that precipitates ventricular arrhythmias and sudden death. The purpose of the present consensus report of the Study Group on ARVD/C of the Working Groups on Myocardial and Pericardial Disease and Arrhythmias of the European Society of Cardiology and of the Scientific Council on Cardiomyopathies of the World Heart Federation is to review the considerable progress in our understanding of the etiopathogenesis, morbid anatomy, and clinical presentation of ARVD/C since it first was described in 1977. The present article focuses on important but still unanswered issues, mostly regarding risk stratification, clinical outcome, and management of affected patients. Because ARVD/C is relatively uncommon and any one center may have experience with only a few patients, an international registry is being established to accumulate information and enhance the numbers of patients that can be analyzed and thus answer pending questions. The registry also will facilitate pathological, molecular, and genetics research on the causes and pathogenesis of the ARVD/C. Furthermore, availability of an international database will enhance awareness of this largely unrecognized condition among the medical community. Physicians are encouraged to enroll patients in the International Registry of ARVD/C.

Arrhythmogenic Right Ventricular Dysplasia↗
PubMed2000

Moving toward a new definition of acute myocardial infarction for the 21st century: status of the ESC/ACC consensus conference. European Society of Cardiology and American College of Cardiology.

The European Society of Cardiology and American College of Cardiology established their initial Joint Consensus Conference in July 1999 to develop a new definition of Acute Myocardial Infarction. This action was deemed necessary because of the development of new sensitive biochemical markers of myocardial necroses: Troponins T and I. There were 5 working groups, including one in Electrocardiography. The Conference adopted a definition that required only a history of "ischemic symptoms" and "a typical rise and fall" of at least one of the biochemical markers. The ECG Working Group strongly advised that a term distinctive from "myocardial infarction" such as "myocardial necrosette" be adopted as the diagnosis for an acute coronary event during which the peak biochemical marker level is below that which occurs when serial evolutionary ECG changes are observed. A pilot substudy from the GUSTO IIa Clinical Trial has identified the low end of the "ECG Change Range" to be: >2x the upper limit of normal for CK-MB, > 11 x for Troponin T, and >6 x for Troponin I.

Creatine Kinase↗
PubMed2000

Electrocardiographic features of inherited diseases that predispose to the development of cardiac arrhythmias, long QT syndrome, arrhythmogenic right ventricular cardiomyopathy/dysplasia, and Brugada syndrome.

Analysis of the 12-lead electrocardiogram (ECG) provides important diagnostic and prognostic information in the long QT syndrome. The clinical diagnosis of long QT syndrome is determined by the presence of a QTc > or = 0.44 sec. A normal QTc does not exclude a family member from being a genetic carrier. The ECG patterns of depolarization, the ST segment and shape of the T-wave can provide important clues as to the affected gene, particularly in conjunction with clinical information as to the precipitating causes of syncope or cardiac events. In arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D), the typical ECG pattern consists of T-wave inversion beyond lead V1. Evidence of right ventricular parietal block is manifest by a QRS duration in V1 > or = 110 msec and a longer QRS duration in the right then left precordial leads. Evidence of slow fractionated conduction is present as epsilon waves. The signal averaged ECG may show exceedingly long and low late potentials. Information regarding the risk of sudden death may also be obtained from the ECG. The ECG changes alone or in combination can provide strong evidence for the diagnosis of ARVC/D and helps to differentiate ARVC/D from right ventricular outflow tract (RVOT) tachycardia. The typical pattern of the ECG in the Brugada syndrome is ST segment elevation in the right precordial leads. This abnormality can be dormant and elicited by administration of drugs that cause Na channel blockade, such as ajmaline or type 1a or 1C antiarrhythmic drugs. Individuals who do not have the Brugada ECG findings at baseline but have this pattern induced by antiarrhythmic drugs are also at risk for sudden death. Further risk stratification may be obtained in the asymptomatic patients if ventricular fibrillation is induced at electrophysiological study.

Arrhythmogenic Right Ventricular Dysplasia↗
PubMed2000

Arrhythmogenic right ventricular dysplasia/cardiomyopathy: need for an international registry. European Society of Cardiology and the Scientific Council on Cardiomyopathies of the World Heart Federation.

Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) is a heart muscle disease characterized by peculiar right ventricular involvement and electrical instability that precipitates ventricular arrhythmias and sudden death. The purpose of the present consensus report of the Study Group of the European Society of Cardiology and the Scientific Council on Cardiomyopathies of the World Heart Federation is to review the considerable progress in our understanding of the etiopathogenesis, morbid anatomy, and clinical presentation of ARVD/C since its first description in 1977. This article will focus on the important but still unanswered issues, mostly regarding risk stratification, clinical outcome, and management of affected patients. Because ARVD/C is relatively uncommon and any one center may have experience with only a few patients, an international registry is being established to accumulate information and enhance the numbers of patients that can be analyzed to answer the pending questions. The registry also will facilitate pathologic, molecular, and genetics research on the etiology and pathogenesis of the disease. Furthermore, availability of an international database will enhance awareness of this largely unrecognized condition among the medical community. Physicians are encouraged to enroll patients in the International Registry of ARVD/C.

Arrhythmias, Cardiac↗
PubMed1999

Thrombogenic factors and recurrent coronary events.

BACKGROUND: Thrombosis is a pivotal event in the pathogenesis of coronary disease. We hypothesized that the presence of blood factors that reflect enhanced thrombogenic activity would be associated with an increased risk of recurrent coronary events during long-term follow-up of patients who have recovered from myocardial infarction. METHODS AND RESULTS: We prospectively enrolled 1045 patients 2 months after an index myocardial infarction. Baseline thrombogenic blood tests included 6 hemostatic variables (D-dimer, fibrinogen, factor VII, factor VIIa, von Willebrand factor, and plasminogen activator inhibitor-1), 7 lipid factors [cholesterol, triglycerides, HDL cholesterol, LDL cholesterol, lipoprotein(a), apolipoprotein (apo)A-I, and apoB], and insulin. Patients were followed up for an average of 26 months, with the primary end point being coronary death or nonfatal myocardial infarction, whichever occurred first. The hemostatic, lipid, and insulin parameters were dichotomized into their top and the lower 3 risk quartiles and evaluated for entry into a Cox survivorship model. High levels of D-dimer (hazard ratio, 2.43; 95% CI, 1.49, 3.97) and apoB (hazard ratio, 1.82; 95% CI, 1.10, 3.00) and low levels of apoA-I (hazard ratio, 1.84; 95% CI, 1.10, 3.08) were independently associated with recurrent coronary events in the Cox model after adjustment for 6 relevant clinical covariates. CONCLUSIONS: Our findings indicate that a procoagulant state, as reflected in elevated levels of D-dimer, and disordered lipid transport, as indicated by low apoA-1 and high apoB levels, contribute independently to recurrent coronary events in postinfarction patients.

Adult↗
PubMed1999

Radiofrequency ablation of an accessory pathway years after heart transplant: a case report.

A patient who had an orthotopic heart transplantation performed 9 years previously presented with a history of tachycardia lasting for three hours. He had only 1 previous episode of sustained tachycardia 4 years previously. Electrophysiological study showed a left antero-lateral accessory pathway which was successfully ablated using radiofrequency energy. This report indicates that some pathways may remain dormant for a long time after heart transplantation.

Adult↗
PubMed1999

Bio-battery signal predicts myocardial lesion formation and depth in vitro.

AIMS: The aim of this study was to determine if the bio-battery signal can predict myocardial lesion formation and depth. METHODS: Fresh bovine ventricular myocardium was immersed in a temperature-controlled bath of circulating blood. RF energy was delivered with a custom generator to a catheter electrode. RF energy, electrode temperature, bio-battery signal and tissue impedance were displayed and recorded. A copper return plate was placed in the bath. RESULTS: When 50 volts of constant RF energy was terminated at a 20, 40, or 60% decline from the maximum bio-battery signal, the lesion depth was 4 +/- 0.4 mm. When RF energy application was terminated later, at a point characterized by a brief change of slope of the bio-battery signal, the lesions measured 7.8 +/- 1.4 mm in depth. This "bump" occurred before a rapid impedance rise. CONCLUSION: The depth of lesions created at the "bump" point was almost two-fold deeper than those at the termination points of 20, 40 and 60% bio-battery decrease (p = 0.0001). When RF energy was terminated at the rapid impedance rise the lesions were similar in depth, 8.2 +/- 0.9 mm, to those obtained when RF energy was stopped at the "bump" (p = 0.28). The bio-battery signal provides a unique marker that might be useful to obtain maximum lesion depth while avoiding rapid impedance rise.

Animals↗
PubMed1999

Arrhythmogenic right ventricular dysplasia in an American Indian woman.

Arrhythmogenic right ventricular (RV) dysplasia consists of a dilatation of the right ventricle with a reduction of RV ejection fraction with fibrofatty replacement of the RV myocardium in the face of a well-preserved left ventricular systolic function. Arrhythmogenic RV dysplasia, which is a cause of sudden unexpected death, has been reported from many geographic areas, including the United States, Europe, and the Far East. This case report presents the first case of arrhythmogenic RV dysplasia in an American Indian (Native American) patient.

Arrhythmogenic Right Ventricular Dysplasia↗
PubMed1998

Baroreflex sensitivity and heart-rate variability in prediction of total cardiac mortality after myocardial infarction. ATRAMI (Autonomic Tone and Reflexes After Myocardial Infarction) Investigators.

BACKGROUND: Experimental evidence suggests that autonomic markers such as heart-rate variability and baroreflex sensitivity (BRS) may contribute to postinfarction risk stratification. There are clinical data to support this concept for heart-rate variability. The main objective of the ATRAMI study was to provide prospective data on the additional and independent prognostic value for cardiac mortality of heart-rate variability and BRS in patients after myocardial infarction in whom left-ventricular ejection fraction (LVEF) and ventricular arrhythmias were known. METHODS: This multicentre international prospective study enrolled 1284 patients with a recent (<28 days) myocardial infarction. 24 h Holter recording was done to quantify heart-rate variability (measured as standard deviation of normal to normal RR intervals [SDNN]) and ventricular arrhythmias. BRS was calculated from measurement of the rate-pressure response to intravenous phenylephrine. FINDINGS: During 21 (SD 8) months of follow-up, the primary endpoint, cardiac mortality, included 44 cardiac deaths and five non-fatal cardiac arrests. Low values of either heart-rate variability (SDNN <70 ms) or BRS (<3.0 ms per mm Hg) carried a significant multivariate risk of cardiac mortality (3.2 [95% CI 1.42-7.36] and 2.8 [1.24-6.16], respectively). The association of low SDNN and BRS further increased risk; the 2-year mortality was 17% when both were below the cut-offs and 2% (p<0.0001) when both were well preserved (SDNN >105 ms, BRS >6.1 ms per mm Hg). The association of low SDNN or BRS with LVEF below 35% carried a relative risk of 6.7 (3.1-14.6) or 8.7 (4.3-17.6), respectively, compared with patients with LVEF above 35% and less compromised SDNN (> or = 70 ms) and BRS (> or = 3 ms per mm Hg). INTERPRETATION: ATRAMI provides clinical evidence that after myocardial infarction the analysis of vagal reflexes has significant prognostic value independently of LVEF and of ventricular arrhythmias and that it significantly adds to the prognostic value of heart-rate variability.

Aged↗
PubMed1997

Predictors of arrhythmic death and cardiac arrest in the ESVEM trial. Electrophysiologic Study Versus Electromagnetic Monitoring.

BACKGROUND: The purpose of this study was to determine if the presenting ventricular arrhythmia (ventricular tachycardia or ventricular fibrillation/cardiac arrest) predicted the type of arrhythmia recurrence in patients treated with antiarrhythmic drugs. METHODS AND RESULTS: In the previously reported Electrophysiologic Study Versus Electrocardiographic Monitoring (ESVEM) trial, there were 486 patients who were randomized to antiarrhythmic drug testing guided by electrophysiological study or by ambulatory ECG monitoring. Use of a defibrillator (implantable cardioverter-defibrillator, ICD) without stored electrograms among 81 patients precluded determination of the type of arrhythmia recurrence; thus these patients were censored at the time of ICD implantation. Of the 486 patients, 381 presented with ventricular tachycardia and 105 with cardiac arrest. Over a 6-year follow-up period, 285 of the 486 patients had an arrhythmia recurrence; of these, 97 had an arrhythmic death or cardiac arrest as a first recurrence. In the current analysis, all 129 arrhythmic deaths/cardiac arrests that occurred any time during follow-up were evaluated as end points. CONCLUSIONS: Although univariate analysis suggested that there was an association between the presenting arrhythmia and outcome, multivariate analysis failed to substantiate the predictive value of the presenting arrhythmia. Left ventricular ejection fraction was the single most important predictor of arrhythmic death or cardiac arrest. This information may be an important factor in deciding whether to advise ICD therapy.

Aged↗
PubMed1997

Long-term cost-effectiveness of alternative management strategies for patients with life-threatening ventricular arrhythmias. Electrophysiologic Study versus Electrocardiographic Monitoring (ESVEM) Investigators.

BACKGROUND: Serial antiarrhythmic drug testing guided by Holter monitoring and electrophysiologic study had similar clinical outcomes in the Electrophysiologic Study versus Electrocardiographic Monitoring (ESVEM) trial, while patients treated with sotalol had improved outcomes. The purpose of this study was to compare long-term cost-effectiveness of these management alternatives. METHODS: Patients in the ESVEM trial were linked to computerized files of either the Health Care Finance Administration or the Department of Veterans Affairs. Total hospital costs and survival time over five year follow-up were measured using actuarial methods, and cost-effectiveness was calculated. RESULTS: Patients randomized to therapy guided by electrophysiologic study had more hospital admissions, higher costs, and a cost-effectiveness ratio of $162,500 per life year added compared with therapy guided by Holter monitoring. Patients randomized to sotalol had fewer hospitalizations, lower costs, and better survival than patients randomized to other drugs, and sotalol was a dominant strategy in the cost-effectiveness analysis. Patients for whom an effective drug was found had fewer hospital admissions, lower costs, and longer survival. These findings were robust in sensitivity analyses and in bootstrap replications. CONCLUSIONS: Serial drug testing guided by electrophysiologic study had an unfavorable cost-effectiveness ratio relative to Holter monitoring, while sotalol was cost-effective relative to other antiarrhythmic drugs.

Aged↗
PubMed1997

Cylindrical ultrasonic transducers for cardiac catheter ablation.

This study was designed to evaluate the feasibility of using cylindrical ultrasound transducers mounted on a catheter for the ablation of cardiac tissues. In addition, the effects of ultrasound frequency and power was evaluated both using computer simulations and in vitro experiments. Frequencies of 4.5, 6, and 10 MHz were selected based on the simulation studies and manufacturing feasibility. These transducers were mounted on the tip of 7-French catheters and applied in vitro to fresh ventricular canine endocardium, submerged in flowing degassed saline at 37 degree C. When the power was regulated to maintain transducer interface temperature at 90-100 degree C, the 10-, 6-, and 4.5-MHz transducers generated a lesion depth of 5.9 +/- 0.2 mm, 4.6 +/- 1.0 mm, and 5.3 +/- 0.9 mm, respectively. The 10-MHz transducer was chosen for the in vivo tests since the maximum lesion depth was achieved with the lowest power. Two dogs were anesthetized and sonications were performed in both the left and right ventricles. The 10-MHz cylindrical transducers caused an average lesion depth of 6.4 +/- 2.5 mm. In conclusion, the results show that cylindrical ultrasound transducers can be used for cardiac tissue ablation and that they may be able to produce deeper tissue necrosis than other methods currently in use.

Animals↗
PubMed1997

Idiopathic ventricular fibrillation.

Idiopathic ventricular fibrillation is defined as cardiac arrest in the absence of structural heart disease and other identifiable causes of ventricular fibrillation. It occurs in 1% to 9% of survivors of out-of-hospital cardiac arrest. The mean age of these patients is 35 to 40 years, and 70% to 75% are male. The pathogenesis is unknown; psychosocial factors may play a role. Baseline clinical characteristics have not been found to identify the 20% to 30% of patients who will have recurrent cardiac arrest. At present, implantation of an automatic defibrillator is the treatment of choice. Two registries have been established to enhance our knowledge of this unusual catastrophic entity.

Adult↗