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 34,133 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Most patients with a history of sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) are at high risk of recurrence. Implanted defibrillators (ICDs) are highly effective in sensing and converting VT or VF to a perfusing rhythm. "Conventional" antiarrhythmic agents, which primarily block cardiac sodium channels, are relatively ineffective in preventing arrhythmia recurrence; amiodarone and sotalol appear to be effective in reducing recurrence and mortality rates, although the extent of benefit is not well understood. Despite the apparent advantage of ICDs, they have short- and long-term complications, are costly, and their benefit in prolonging the quantity or quality of life remains unproven. Randomized clinical trials which compare the effect of ICDs with that of antiarrhythmic drugs on mortality, cost, and quality of life will be necessary to understand how patients with malignant arrhythmias ought to be treated. If an ICD is implanted, adjunctive therapies need to be considered to treat the underlying heart disease and to derive optimum benefit from the device. Drugs may have beneficial or adverse interactions with devices, and the full understanding of these interactions requires further study.
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PMID:The implantable defibrillator and antiarrhythmic drugs--competitive and complementary treatment for severe ventricular arrhythmia. 826 62

Table 5 can be used as framework for a summary of the previous discussion on pharmacologic therapy for ventricular tachyarrhythmias. The system for grading the severity of symptoms of ventricular tachyarrhythmias, previously presented in Table 3, is arranged vertically along the left side of Table 5. Horizontally across the top, patients are grouped according to the presence or absence of structural heart disease, and those with structural heart disease are further dichotomized according to left ventricular ejection fraction. As can be seen, patients with class I symptoms should not be treated whenever possible, although in patients with reduced left ventricular function (especially coronary heart disease), an argument can be made for empirical treatment with beta-adrenoceptor blocking agents whenever possible. Patients with class II symptoms can be treated empirically with beta-adrenoceptor blocking agents. Other antiarrhythmic agents may be safer when there is no underlying structural heart disease, but this has not been proved. The use of antiarrhythmic agents other than beta-adrenoceptor blocking agents in patients with class II symptoms should probably be guided and monitored by ambulatory electrocardiographic recording and exercise tolerance testing. In the patient with hemodynamically stable ventricular tachycardia, electrophysiologic-guided therapy is probably preferable whenever possible. Encainide, flecainide, and similar drugs should be avoided when there is a possibility of residual ventricular premature depolarizations of three or more per hour. Some uncertainty remains concerning the treatment of patients with class III and class IV symptoms and no structural heart disease. Some patients may fall into a specific group that is very responsive to drug therapy. These patients should probably be treated like other patients with class III and class IV symptoms. Electrophysiologic testing may be helpful. When such patients have a reproducibly induced sustained ventricular tachyarrhythmia, it is likely that antiarrhythmic drug therapy will render the arrhythmia noninducible, and that they will do well while receiving long-term pharmacologic therapy. When such patients do not have a reproducibly induced sustained ventricular tachyarrhythmia, the main controversy is whether therapy is needed. If it is decided that such a patient needs therapy, the choice is usually between empiric amiodarone and an ICD, although catheter ablation may be helpful in selected instances. Patients with class III and class IV symptoms who have structural heart disease require therapy. Although this continues to be an evolving area of investigation, for many of these patients, the initial attempt at therapy should be pharmacologic.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Pharmacologic therapy in patients with ventricular tachyarrhythmias. 843 25

The purpose of this study was to investigate the efficacy and safety of atrial cardioversion using an endocardial single lead system presently used for ventricular defibrillation. The study population consisted of 26 recipients of an ICD in combination with a conventional endocardial single lead system with the proximal spring electrode as anode in the SVC and the distal as cathode in the apex of the RV. Atrial tachyarrhythmias were induced by right atrial burst pacing. If the arrhythmia sustained > 1 minute, biphasic shocks synchronized with the R wave were delivered using the implanted device, beginning with an energy of 4 J. If 4 J failed to terminate the arrhythmia, energy was increased stepwise, if the first shock was successful, a step-down testing was performed after reinduction of atrial tachyarrhythmias. The mean atrial defibrillation threshold was 2.3 +/- 1.2 J (range, 0.5-5 J). A total of 154 shocks were delivered and no adverse effects were observed. The mean defibrillation threshold for atrial flutter was somewhat lower than that for AF (1.8 +/- 1 J vs 2.7 +/- 1.4 J, P = 0.08). There was no correlation between the atrial defibrillation threshold and a history of previously occurring atrial tachyarrhythmias, the kind of the underlying heart disease, a prescription of antiarrhythmic drugs, the dimension of the LA, the LVEF, or the ventricular DFT. Internal atrial cardioversion of short duration atrial tachyarrhythmias using a transvenous single lead system designed for ventricular defibrillation is feasible and safe at low energies, and may have important clinical applications.
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PMID:Low energy transvenous cardioversion of short duration atrial tachyarrhythmias in humans using a single lead system. 912 73

The influence of the clinical presentation on the long-term outcome in 213 consecutive patients with ICDs, ECG storage capability, and nonthoracotomy leads, was analyzed. Sixty-six patients presented with cardiac arrest (CA), 81 patients with hemodynamically stable VT, and 66 patients with syncope (SY). Patient characteristics were: mean age CA 62, VT 61, SY 61 years; mean ejection fraction CA 31%, VT 29%, SY 30%; coronary artery disease CA 71%, VT 71%, SY 64% (all P > 0.05 Fisher's exact test); female gender CA 40%, VT 14%, SY 19% (CA vs VT and SY, P < 0.005); inducibility by programmed stimulation CA 50%, VT 84%, SY 61% (VT vs CA and SY, P < 0.001, CA vs SY, P > 0.05). During a mean follow-up of 14.5 months, 29 patients died: CA 12%, VT 14%, SY 9% (P > 0.05). Comparing Kaplan-Meier curves, no difference in the time course of overall mortality was found (log-rank P > 0.05). In the CA, VT, and SY groups, 543, 1,630, and 189 ICD therapies (including antitachycardia pacing, low energy cardioversion, and defibrillation) were observed, respectively. Actuarial analysis showed a shorter interval between implantation and first ICD therapy for VT versus CA and SY (log-rank P < 0.005). Patients presenting with VT experienced earlier and more frequent ICD therapies than patients with CA or SY independent of age, ejection fraction, and heart disease. No difference in overall mortality and time course of fatal events was observed among the three groups.
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PMID:Does the initial presentation of patients with implantable defibrillator influence the outcome? 912 84

This report describes how acute-care community hospitals in the United States get paid for services when their patients either are entitled to Medicare or Medicaid benefits or subscribe to a Blue Cross or Blue Shield plan, a commercial insurance plan, a health maintenance organization, a preferred provider organization, or some other third-party payment mechanism. The focus of this report is on cardiac services, which are the most common type of inpatient services provided by acute-care community hospitals. Over the past three decades, extraordinary advances in medical and surgical technologies as well as healthier life-styles have cut the annual death rate for coronary heart disease in half. Despite this progress, cardiovascular disease remains the number one cause of hospitalization. On average nationwide, diseases and disorders of the circulatory system are the primary reason for 17 percent of all patient admissions, and among the nation's 35 million Medicare beneficiaries they are the primary reason for 25 percent of all admissions. In the United States heart disease is the leading cause of death and a major cause of morbidity. Its diagnosis and treatment are often complex and costly, often requiring multiple hospitalizations and years of medical management. To focus management attention and resources on the immense cardiology marketplace, many hospitals have hired individuals with strong clinical backgrounds to manage their cardiology programs. These "front-line" managers play a key role in coordinating a hospital's services for patients with cardiovascular disease. Increasingly, these managers are being asked to become active participants in the reimbursement process. This report was designed to meet their needs. Because this report describes common reimbursement principles and practices applicable to all areas of hospital management and because it provides a "tool kit" of analytical, planning, and forecasting techniques, it could also be useful to hospital marketing, planning, finance, and accounting personnel. In addition, the rich reservoir of data contained in the appendixes to this report may be of interest to hospital chief executive officers, cardiologists, and cardiovascular surgeons. In addition to the introduction and summary sections, this report contains five main sections. Sequentially, these deal with: the ways hospitals get paid for what they do; ICD-9 coding DRGs, PPS, and Medicare claims administration; ways to analyze how well your hospital is doing; planning and forecasting; the new Resource-Based Relative Value Scale.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Payment of hospital cardiac services. 1011 96

Prospective identification of patients with structural heart disease who could profit from prophylactic ICD therapy is hampered by the low predictive power of the currently available risk stratification parameters. Microvolt T wave alternans measured noninvasively is a new promising parameter to assess impaired ventricular repolarization which has been associated with an increased incidence of ventricular tachyarrhythmias. T wave alternans is rate-dependent; to induce alternans, heart rate may be increased by atrial stimulation during invasive EP testing or noninvasively by exercise stress testing. The first clinical validation with respect to prediction of inducibility of ventricular tachyarrhythmias and of arrhythmic events during follow-up in patients undergoing invasive EP testing was reported in 1994. Subsequently, a good concordance between the results of invasive and noninvasive assessment of T wave alternans was demonstrated by our group. The first prospective evaluation of the noninvasive alternans measurement using submaximal exercise testing was performed in patients surviving prehospital ventricular fibrillation or sustained ventricular tachycardia referred to our institution. The occurrence of T wave alternans in this patient population was predictive of future tachyarrhythmic events with subsequent appropriate ICD therapy. The results of the currently performed prospective trials in various patient populations will help to establish the utility of T wave alternans assessment as a risk stratifier in clinical practice.
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PMID:[Microvolt level T wave alternans: a new marker for noninvasive risk stratification]. 1081 Jul 86

The majority of cardioverter/defibrillator (ICD) implantations are currently performed with a non-thoracotomy approach. From November 1993 to January 1995, 46 patients underwent implantation of a PCD 7219C with an "active-can" lead configuration at our institution. While the chronic stability of the defibrillation threshold (DFT) for an epicardial lead system is well established, the results are still inconsistent for non-thoracotomy lead systems. Accordingly, the aim of the present study was to compare the acute and chronic defibrillation thresholds of the ICDs implanted with an "active-can" lead system in order to assess the chronic stability of these systems. The defibrillation energy requirements were measured at implant, prior to hospital discharge, three, six and twelve months after implantation of the defibrillator. The patient group consisted of 8 females and 38 males with a mean age of 57.2 years. The mean left ventricular ejection fraction was 43.8%. The most frequent underlying heart disease was coronary artery disease in 31 of 46 patients. Eight patients had idiopathic dilated cardiomyopathy. In 39 of 46 patients, the defibrillation threshold could be successfully determined at all 4 time points after implantation. The mean defibrillation energy requirement at the time of implantation was 9.2 +/- 5.9 Joules (J). The subsequent mean energy requirements were 7.6 +/- 4.8 J at pre-hospital discharge, 8.6 +/- 5.7 J at the 3 month, 8.1 +/- 6.0 J at the 6 month and 8.6 +/- 5.8 J at the 12 month follow-up visits. The mean defibrillation threshold was lowest at the time of prehospital discharge, significantly lower than at the time of initial implantation (p = 0.021). However, at all later time points up to one year, there was no significant difference in the DFT as compared with the time of initial implantation. Comparing the DFT at the time of implantation and the DFT at all other time points, there were no significant differences (9.23 vs. 8.56 J, p = 0.291). Although there was an initial decrease in the DFT at seven to ten days, the long-term stability of the DFT up to one year remained stable in the devices with the "active-can" lead system.
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PMID:[Implantable cardioverter/defibrillator: long-term stability of the defibrillation threshold with a unipolar electrode configuration (active-can")]. 1107 87

In patients with structural heart disease and sustained symptomatic ventricular tachycardia or ventricular fibrillation without reversible cause, the implantable cardioverter-defibrillator has become the therapy of first choice. Besides the "MADIT indication", however, arrhythmia risk stratification with regard to prophylactic ICD implantation is an unsolved problem. This overview summarizes the currently very limited clinical value of potential risk predictors for sudden cardiac death in postinfarct patients and in patients with dilated cardiomyopathy.
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PMID:[Risk stratification for sudden cardiac death in post-infarct patients and in patients with dilated cardiomyopathy]. 1115 69

A growing number of Japanese patients are being treated with ICDs. Efforts are warranted to minimize the rates of ICD shocks that cause discomfort and anxiety. The circadian distribution of ICD discharges was investigated in 80 patients (57+/-10 years of age, 69 men) from ten Japanese medical centers. The underlying heart disease was ischemic in 27 versus nonischemic in 53 patients. All patients had refractory VT or VF, and received appropriate shocks confirmed by stored data retrieved from the memory of the ICD. In the analysis of 354 appropriate shocks delivered in the overall population, a morning peak in VT or VF episodes was observed. However, subgroup analyses of the circadian distribution of ICD shocks revealed that the morning peak in VT or VF episodes was confined to patients with ischemic heart disease and was blunted by treatment patients with beta-adrenergic blockers. The absence of a morning peak in appropriate ICD shocks among patients with nonischemic heart disease remains unexplained and was unrelated to the use of beta-adrenergic blockers. In conclusion, the circadian pattern of appropriate ICD discharges was related to the underlying heart disease. In patients with ischemic heart disease, recurrences of VT or VF peaked in the morning. In contrast, in patients without ischemic heart disease, the episodes of VT or VF were evenly distributed during waking hours. Beta-adrenergic blockers appeared to blunt the morning peak in VT or VF among patients with ischemic heart disease.
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PMID:Absence of a morning peak in ventricular tachycardia and fibrillation events in nonischemic heart disease: analysis of therapies by implantable cardioverter defibrillators. 1181 28

The smaller venous capacitance in infants and small children may hamper transvenous ICD lead implantation, and epicardial approaches require thoracotomy and have associated complications. The study evaluated the feasibility and performance of subcutaneous arrays and active can ICDs without transvenous shocking coils or epicardial patches. An immature and mature pig were anesthetized and ventilated. A pacing lead was inserted in the right ventricle for fibrillation induction and rate sensing. Subcutaneous arrays were positioned in the right and left chest walls. An ICD emulator was placed in abdominal and prepectoral pockets. Fluoroscopic images were acquired for each electrical vector configuration (array --> can, can --> array, array --> array, array + array --> can). Ventricular fibrillation was induced and DFT testing performed. Defibrillation was achieved in all ten trials in the immature piglet, with DFT < or = 9 J, regardless of vector configuration. Using a single subcutaneous array and active can, the shock impedance ranged from 28-36 ohms. With two arrays, shocking impedance fell to 15-22 ohms. In the adult pig, defibrillation was not accomplished with maximum energy of 40 J, using all vector configurations. Using data garnered from these experiments, this technique was then successfully performed in a 2-year-old child with VT and repaired congenital heart disease, needing an ICD. This study demonstrates the feasibility of leadless ICD implantation in an immature animal and successful implementation in a small child. A single subcutaneous array and active can resulted in excellent implant characteristics and DFTs with a minimally invasive approach. Defibrillation was not possible in a larger animal, possibly due to maximal available energy. This may be of value for small children requiring ICD implantation.
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PMID:Minimally invasive cardioverter defibrillator implantation for children: an animal model and pediatric case report. 1181 14


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