Major depression before and after myocardial infarction: its nature and consequences.

The prevalence and prognostic impact of previous depression, depression in the hospital, and depression after discharge were studied in 222 patients admitted for acute myocardial infarction (MI). Patients were interviewed 1 week, 6 months, and 12 months after the index MI using a modified version of the Diagnostic Interview Schedule (DIS); patients also completed the Beck Depression Inventory (BDI). Patients or family members were recontacted at 18 months to determine survival.

The impact of negative emotions on prognosis following myocardial infarction: is it more than depression?

This study examine the importance of major depression symptoms, history of major depression, anxiety, anger-in, anger-out, and perceived social support, measured in the hospital after a myocardial infarction (MI), in predicting cardiac events over the subsequent 12 months in a sample of 222 patients. Cardiac events included both recurrences of acute coronary syndromes (unstable angina admissions and survived and nonsurvived MI recurrences) and probable arrhythmic events (survived cardiac arrests and arrhythmic deaths). Major depression, depressive symptoms, anxiety, and history of major depression all significantly predicted cardiac events.

Depression and 18-month prognosis after myocardial infarction.

Background: We previously reported that major depression in patients in the hospital after a myocardial infarction (MI) substantially increases the risk of mortality during the first 6 months. We examined the impact of depression over 18 months and present additional evidence concerning potential mechanisms linking depression and mortality.

Methods And Results: Two-hundred twenty-two patients responded to a modified version of the National Institute of Mental Health Diagnostic Interview Schedule (DIS) for a major depressive episode at approximately 7 days after MI.

The treatment of atrial fibrillation. An evaluation of drug therapy, electrical modalities and therapeutic considerations.

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia in clinical practice, and is responsible for considerable morbidity. Basic studies have shown that AF is usually due to the coexistence of multiple functional atrial re-entry circuits, and that the main determinant of its haemodynamic manifestations is the ventricular response rate. The major adverse clinical consequences of AF include palpitations, impaired cardiac function and thromboembolism.

Catheter ablation using radiofrequency or low-energy direct current in pediatric patients with the Wolff-Parkinson-White syndrome.

Percutaneous ablation of accessory pathways was performed in 22 consecutive children and adolescents (9 boys and 13 girls, age range 8 to 18 years). Low-energy direct current (DC) was used exclusively in the first 6 patients, whereas ablation was performed with radiofrequency energy in the following 16. Accessory pathways were located in the left free wall in 15 patients, were posteroseptal in 3, were in the right free wall in 3 and were anteroseptal in 1.

Results of a comparative study of low energy direct current with radiofrequency ablation in patients with the Wolff-Parkinson-White syndrome.

Objective: To compare two new power sources for catheter ablation in patients with the Wolff-Parkinson-White syndrome.

Design: 120 consecutive patients with accessory pathways had catheter ablation. Low energy direct current (DC) was used in the first 60 patients and radio-frequency current in the next 60 patients.

Depression following myocardial infarction. Impact on 6-month survival.

Objective: To determine if the diagnosis of major depression in patients hospitalized following myocardial infarction (MI) would have an independent impact on cardiac mortality over the first 6 months after discharge.

Design: Prospective evaluation of the impact of depression assessed using a modified version of the National Institute of Mental Health Diagnostic Interview Schedule for major depressive episode. Cox proportional hazards regression was used to evaluate the independent impact of depression after control for significant clinical predictors in the data set.

Rate-dependent functional properties of retrograde atrioventricular nodal conduction in experimental animals.

While rate-dependent atrioventricular (AV) nodal functional properties play a major role in determining antegrade AV nodal conduction, their existence and characteristics have not been assessed during retrograde AV nodal impulse propagation. Pacing protocols were used to study selectively AV nodal recovery, facilitation, and fatigue in 6 isolated, superfused rabbit AV nodal preparations and in 11 morphine-chloralose anesthetized dogs. All three properties were identifiable during retrograde AV nodal activation in rabbits.

Comparative mechanisms of antiarrhythmic drug action in experimental atrial fibrillation. Importance of use-dependent effects on refractoriness.

Background: Antiarrhythmic drugs are considered to terminate atrial fibrillation by prolonging refractoriness, but direct experimental evaluation of this concept has been limited. The atria are activated rapidly during atrial fibrillation, and antiarrhythmic drugs are known to have important rate-dependent actions. The potential role of such properties in determining drug effects during atrial fibrillation has not been evaluated.

Rate-dependent effects of diltiazem on human atrioventricular nodal properties.

Background: Tachycardia enhances the channel-blocking effects of antiarrhythmic drugs. In contrast to the extensive data regarding the rate-dependent effects of sodium channel blockers in humans, little is known about the frequency-dependent effects of calcium channel blockers on human atrioventricular (AV) nodal properties. Accordingly, the purpose of this study was to evaluate the importance of heart rate in modulating the electrophysiological effects of diltiazem in humans.

A quantitative analysis of use-dependent ventricular conduction slowing by procainamide in anesthetized dogs.

Background: Use-dependent effects of antiarrhythmic drugs on phase 0 sodium current result in rate-dependent conduction slowing with important potential clinical consequences. The purpose of the present study was to determine whether state-dependent interactions of procainamide with sodium channels can be analyzed based on conduction changes in vivo.

Methods And Results: Procainamide infusions were used to produce stable drug concentrations causing greater than or equal to 25% conduction slowing at a basic cycle length (BCL) of 300 msec in morphine/chloralose-anesthetized dogs with formalin-induced atrioventricular block.

Effects of flecainide on the rate dependence of atrial refractoriness, atrial repolarization and atrioventricular node conduction in anesthetized dogs.

Unlabelled: Flecainide is effective against certain supraventricular arrhythmias (atrial fibrillation and atrioventricular [AV] node reentrant tachycardia), but its mechanisms of action are unknown. Previous in vitro work suggests that flecainide attenuates rate-dependent action potential duration shortening, producing tachycardia-dependent prolongation of the refractory period. This study was designed to assess whether similar changes occur in vivo and whether the effects of flecainide on AV node conduction depend on heart rate and on direction of propagation (anterograde vs.

Effects of beta-adrenergic receptor stimulation and blockade on rate-dependent atrioventricular nodal properties.

Recent work has shown that alterations in the dynamic atrioventricular (AV) nodal response to changes in heart rate can significantly modify AV nodal function. The present study was designed to evaluate the nature and potential importance of sympathetic regulation of the rate-dependent properties of the AV node. Selective stimulation protocols and mathematical formulations were used to independently quantify AV nodal recovery, facilitation, and fatigue in 12 morphine-chloralose-anesthetized dogs.

Success, safety, and late electrophysiological outcome of low-energy direct-current ablation in patients with the Wolff-Parkinson-White syndrome.

Background: Percutaneous ablation of accessory pathways with the use of a defibrillator can be accomplished with high-energy direct-current (DC) shocks of 150-400 J, but complications include cardiac tamponade and sudden cardiac death, mostly resulting from significant electrical arcing and barotrauma. A new low-energy DC power source with a brief time-constant capacitive discharge delivers shocks of 2-40 J and eliminates or greatly reduces arcing. This report describes our initial experience with this device in 60 consecutive patients (mean age, 34 years; range, 9-67 years) with Wolff-Parkinson-White syndrome.

Low energy direct current ablation in patients with the Wolff-Parkinson-White syndrome: clinical outcome according to accessory pathway location.

Forty-five patients with the Wolff-Parkinson-White syndrome underwent direct current (DC) ablation using a low energy power source (Cardiac Recorders). Anodal shocks of 10-40 joules were given to either a 6 French quadripolar catheter (Bard), a 7 French bipolar contoured catheter (Bard), or a 7 French deflectable catheter with a 4-mm distal electrode (Mansfield). The indifferent electrode consisted of a large patch that was positioned under the left scapula.

Dynamics of heart rate.

Heart rate oscillates on several different time scales and has long-term variability in the form of 1/f noise. The physiological control of heart rate is briefly reviewed, and several typical patterns of heart rate variability, in health and sickness, are described. Considered briefly are some possible dynamical mechanisms for heart rate variability.

Quantitation of dynamic AV nodal properties and application to predict rate-dependent AV conduction.

A number of functional properties of the atrioventricular (AV) node have been described in response to changes in the atrial input rate. The purpose of this study was 1) to develop quantitative descriptors of these properties, and 2) to determine whether they can account for rate-dependent changes in AV nodal conduction. The delay in AV nodal conduction of single premature beats (recovery) was found to be an exponential function of coupling interval with a time constant of 66 +/- 2 (+/- SE) ms.

Kinetics of use-dependent ventricular conduction slowing by antiarrhythmic drugs in humans.

Background: Rate-dependent conduction slowing by class I antiarrhythmic agents has clinically important consequences. Class I drugs are known to produce use-dependent sodium channel blockade. If rate-dependent conduction slowing by class I agents is due to sodium channel blocking actions, the kinetics of conduction slowing should be similar to those of depression of sodium current indexes in vitro.

A unified model of atrioventricular nodal conduction predicts dynamic changes in Wenckebach periodicity.

The atrioventricular (AV) node responds in a complex fashion to changes in activation rate. A variety of approaches have been used to explain these dynamic AV nodal responses, but none has been able to account fully for AV nodal behavior. Three specific rate-dependent properties of the AV node have been described: 1) time-dependent recovery after excitation, 2) an effect of short cycles to advance recovery ("facilitation"), and 3) a gradual slowing of conduction in response to sustained, high-frequency activation ("fatigue").

Atrial fibrillation in patients with an accessory pathway: importance of the conduction properties of the accessory pathway.

To investigate how the electrophysiologic properties of the accessory pathway affect the occurrence of atrial fibrillation in the Wolff-Parkinson-White syndrome, programmed stimulation data of 57 patients with overt pre-excitation and 33 patients with a concealed accessory pathway with documented circus movement tachycardia were reviewed. Atrial fibrillation had occurred spontaneously in 31 (54%) of the 57 patients with the Wolff-Parkinson-White syndrome and in 1 (3%) of the 33 with a concealed accessory pathway (p less than 0.001).