Effect of d-sotalol on mortality in patients with left ventricular dysfunction after recent and remote myocardial infarction. The SWORD Investigators. Survival With Oral d-Sotalol

BACKGROUND

Left ventricular dysfunction after myocardial infarction is associated with an increased risk of death. Other studies have suggested that a potassium-channel blocker might reduce this risk with minimal adverse effects. We investigated whether d-sotalol, a pure potassium-channel blocker with no clinically significant beta-blocking activity, could reduce all-cause mortality in these high-risk patients.

METHODS

Patients with a left ventricular ejection fraction of 40% or less and either a recent (6-42 days) myocardial infarction or symptomatic heart failure with a remote (> 42 days) myocardial infarction were randomly assigned d-sotalol (100 mg increased to 200 mg twice daily, if tolerated) or matching placebo twice daily.

FINDINGS

After 3121 of the planned 6400 patients had been recruited, the trial was stopped. Among 1549 patients assigned d-sotalol, there were 78 deaths (5.0%) compared with 48 deaths (3.1%) among the 1572 patients assigned placebo (relative risk 1.65 [95% CI 1.15-2.36], p = 0.006). Presumed arrhythmic deaths (relative risk 1.77 [1.15-2.74], p = 0.008) accounted for the increased mortality. The effect was greater in patients with a left ventricular ejection fraction of 31-40% than in those with lower ( <or= 30%) ejection fractions (relative risk 4.0 vs 1.2, p = 0.007).

INTERPRETATION

Among the 1549 patients evaluated, administration of d-sotalol was associated with increased mortality, which was presumed primarily to be due to arrhythmias. The prophylactic use of a specific potassium-channel blocker does not reduce mortality, and may be associated with increased mortality in high-risk patients after myocardial infarction.

Autonomic dysfunction after catheter ablation

Autonomic dysfunction may occur as a consequence of radiofrequency (RF) catheter ablation of a variety of supraventricular tachycardias. Effects suggestive of autonomic dysfunction that may be seen acutely during the ablation procedure include sudden profound slowing of the sinus rate or transient AV block. These abnormalities may occur during application of RF current, typically along the tricuspid or mitral annulus, at sites distant from both the sinus and AV nodes; they resolve quickly when RF current delivery is terminated. The most common long-term indication of autonomic dysfunction after ablation is inappropriate sinus tachycardia. This complication, rarely a lasting significant clinical problem, is seen after AV node modification and after ablation of accessory pathways. It usually resolves within several months. The mechanism appears to be loss of parasympathetic influence on the sinus node. Autonomic dysfunction after ablation of ventricular tachycardia has not yet been described, but could occur as newer catheter technologies capable of producing larger lesions are perfected.

Histologic evolution of radiofrequency lesions in an old human myocardial infarct causing ventricular tachycardia

INTRODUCTION

Radiofrequency (RF) ablation of ventricular tachycardia (VT) late after myocardial infarction may be difficult due to characteristics of the infarct containing the reentry circuit. RF lesions in these infarcts in humans have not been characterized.

METHODS AND RESULTS

Catheter mapping and ablation of VT originating from an anterior wall infarct was performed 8 days and again 12 hours prior to death. Pacing identified a region of abnormal conduction where RF ablation terminated VT. This region contained strips of myocytes sandwiched between endocardial fibrosis and dense scar. RF lesions ranged from 2 x 2 mm to 5 x 10 mm and were up to 3 mm in depth. Acute lesions showed superficial thrombus and early coagulation necrosis without inflammation. Older lesions showed coagulation necrosis, sparse neutrophil infiltrate, minimal granulation tissue, hemorrhage, and mixed inflammatory infiltrate along the lumen without re-endothelialization.

CONCLUSION

In this patient, RF lesions had sufficient depth but not width to interrupt the thin, but potentially broad, sheets of myocytes in the reentry circuit. In thinned areas, RF lesions can extend to the epicardium. Selecting sites with abnormal electrograms confines RF lesions to the infarct region. Inflammation and hemorrhage could conceivably cause delayed effects of RF.

New observations on decremental atriofascicular and nodofascicular fibers: implications for catheter ablation

INTRODUCTION

The purpose of this study was to characterize the anatomy and physiology of accessory pathways that exhibit anterograde decremental conduction.

RESULTS

Among 100 consecutive patients with an accessory pathway undergoing electrophysiological study, six individuals with decremental anterograde accessory pathway conduction were identified. Anterograde accessory pathway effective refractory periods and conduction curves were assessed by atrial extrastimulus testing. Atrial pace mapping and ventricular activation sequence mapping were used to define accessory pathway origin and insertion. Surgical ablation (N = 1) or radiofrequency catheter ablation (N = 3) was performed based on accessory pathway anatomy as determined during electrophysiological study. Four of 6 patients had gaps in anterograde accessory pathway conduction. Two patients had evidence of functional longitudinal dissociation in the accessory pathway. Five of 6 patients had atriofascicular fibers with an atrial rather than AV nodal site of origin of their decrementally conducting accessory pathway and with distal insertions in the right bundle branch. Among these five patients, a right posterior atrial origin was nearly as common as a right anterior atrial origin. One patient had a true nodofascicular fiber that arose from the AV node, inserting distally into the left bundle branch.

CONCLUSION

Most accessory pathways with anterograde decremental conduction arise from the right anterior or right posterior atrium, not the AV node. A gap in anterograde accessory pathway conduction and functional longitudinal dissociation are common in such accessory pathways. Surgical or catheter ablation of such pathways is effective when directed at the atrial origin of the accessory pathway. True nodofascicular fibers arising from the AV node are rare. These may insert distally in the left ventricle. Catheter ablation of the proximal origin of such fibers is likely to result in complete AV block.

Entrainment techniques for mapping atrial and ventricular tachycardias

Many atrial tachycardias, atrial flutter, and postmyocardial infarction ventricular tachycardias are due to reentry through large "macroreentrant" circuits. These circuits can be difficult to define by catheter mapping of the activation sequence. Entrainment techniques allow the relation of a mapping site to the reentrant circuit to be assessed on a site-by-site basis during catheter mapping. Regions of abnormal conduction that are in the reentrant circuit can be distinguished from bystander sites outside the circuit. A mapping site classification to guide catheter ablation is reviewed.

Alterations of heart rate and of heart rate variability after radiofrequency catheter ablation of supraventricular tachycardia. Delineation of parasympathetic pathways in the human heart

BACKGROUND

Persistent inappropriate sinus tachycardia has been reported as a complication after radiofrequency (RF) ablation of the fast atrioventricular (AV) nodal pathway. The purpose of this study was to evaluate the prevalence of this complication and its mechanism using heart rate variability analysis.

METHODS AND RESULTS

Time and frequency domain analysis of heart rate was performed in the electrophysiology laboratory immediately before and immediately after RF ablation in 64 patients with supraventricular tachycardia. Ablation targets in these 64 patients included the fast AV nodal pathway (n = 3), the slow AV nodal pathway (n = 14), a posteroseptal accessory pathway (n = 23), and a left lateral accessory pathway (n = 24). A control group of 21 patients undergoing diagnostic study but not ablation underwent identical analysis immediately before and at the conclusion of their procedure. Patients undergoing ablation also had time and frequency domain analysis performed on ambulatory 24-hour Holter tapes recorded before ablation and at 1 day, 1 month, and 6 months after ablation. Compared with preablation values, time domain analysis immediately after ablation revealed a significant increase in mean heart rate and significant reductions in heart rate variability expressed as SD, MSSD, and PNN50 in patients undergoing AV nodal modification or posteroseptal accessory pathway ablation. Frequency domain analysis revealed marked attenuation of high frequency (0.15 to 0.40 Hz) components, indicating parasympathetic denervation. These acute changes were not seen after ablation of left lateral accessory pathways or after diagnostic study without ablation. Time and frequency domain analysis of 24-hour ambulatory Holter monitors performed serially after ablation revealed resolution of abnormalities of heart rate and of heart rate variability 1 to 6 months after ablation, with reappearance of the high frequency parasympathetic component suggestive of reinnervation.

CONCLUSIONS

RF ablation in the anterior, mid, and posterior regions of the low interatrial septum may disrupt preganglionic or postganglionic parasympathetic fibers located in these regions that are destined to innervate the sinus node. Such fibers become more scarce along the left AV groove with increasing distance from the posteroseptal space. Parasympathetic denervation may be one mechanism for persistent inappropriate sinus tachycardia after RF ablation.

Intracoronary infusion of dilute ethanol for control of ventricular rate in patients with atrial fibrillation

The effects of selective infusion of 25% ethanol into the AV nodal artery was assessed in 11 patients with atrial fibrillation and uncontrollably rapid ventricular response rates. The primary study objective was to achieve permanent modification of AV nodal function and control ventricular rate without drug therapy and without causing permanent complete AV block. "Clinical success" was defined as drug-free rate control by either AV nodal modification or the production of complete AV block. Selective catheterization and ethanol infusion into the AV nodal artery could be performed in nine patients. Intracoronary ethanol infusion acutely caused second- or third-degree AV nodal block in seven patients and an increase in AV nodal refractory period and Wenckebach cycle length in two patients. Acute occlusion of the AV nodal artery or infarction of nontarget myocardium was not observed. During follow-up of 22.2 +/- 2.2 months the primary study objective was attained in only four of nine patients treated, yielding an efficacy of 44%. However, the "clinical success" rate was 78%. The acute effects of ethanol on AV conduction did not predict the chronic effects. Selective intracoronary infusion of dilute ethanol to control the ventricular rate in atrial fibrillation should be considered when radiofrequency ablation has been unsuccessful. This method of chemical ablation is as effective and probably safer than rapid administration of 96% ethanol.

Current management of the Wolff-Parkinson-White syndrome

In this review, we discuss the pathophysiology of the Wolff-Parkinson-White (WPW) syndrome and describe medical, surgical, and catheter based principles. WPW syndrome results from the congenital presence of impulse-conducting fascicles, known as accessory pathways (APs) or bypass tracts, which connect atria and ventricles across the annulus fibrosis and are capable of preexciting portions of the ventricular myocardium. Once triggered, atrioventricular reciprocating tachycardias (AVRTs) generally result from depolarization wavefronts moving anterograde through the AV node to the ventricles and returning retrograde to the atria along the AP. Rapid AVRT decreases ventricular filling time and cardiac output, resulting in symptoms. Medications that prolong AP refractory periods (flecainide, propafenone, and amiodarone) prevent rapid AP anterograde conduction (from atria to ventricles) in atrial tachycardias such as atrial fibrillation or flutter. In emergencies, adenosine can be used to terminate the AVRT of WPW syndrome. Otherwise, Class IA or IC antiarrhythmic agents are used to slow AP conduction either with or without AV nodal blocking agents. Open chest surgical ablation of a bypass tract in a symptomatic patient was first reported in 1968. The original endocardial surgical techniques for localizing and dividing APs were refined and an alternative epicardial approach has been developed. Reported mortality rates in experienced hands were 0% to 1.5% in large series for patients without additional cardiac abnormalities. Catheter delivered radiofrequency (RF) energy is now applied intravascularly to ablate APs. Since the first large series of patients undergoing RF ablation was reported in 1989, the procedure had proved safe, cost effective, and well tolerated. RF ablation has become the initial nonpharmacological treatment of choice for WPW syndrome; surgical ablation has become relegated to those cases where symptoms are intolerable and RF ablation is not feasible.

Propafenone versus sotalol for suppression of recurrent symptomatic atrial fibrillation

Because conventional antiarrhythmic therapy is often ineffective in maintaining sinus rhythm or is associated with adverse side effects in patients with atrial fibrillation (AF), there is a clinical need to test newer agents. One hundred patients with AF who had unsuccessful therapy with 1.9 +/- 1.0 type IA antiarrhythmic agents were randomized to receive either propafenone (n = 50) or sotalol (n = 50). Patients were stratified into 4 groups based on AF pattern (chronic vs paroxysmal) and left atrial size (large [> or = 4.5 cm] vs small [< 4.5]). The proportion of patients remaining in sinus rhythm on each agent was calculated for each group by the Kaplan-Meier method. For patients randomized to propafenone, 46 +/- 8%, 41 +/- 8% and 30 +/- 8% remained in sinus rhythm at 3, 6 and 12 months, respectively, after cardioversion. A similar proportion of patients treated with sotalol remained in sinus rhythm at follow-up (49 +/- 7%, 46 +/- 8% and 37 +/- 8% at 3, 6 and 12 months, respectively; p = NS). The proportion of patients remaining in sinus rhythm on propafenone and sotalol was not dependent on arrhythmia pattern or left atrial dimension. Except for constipation that occurred more frequently in patients treated with propafenone, adverse side effects were equally distributed between the 2 therapies. Two patients receiving sotalol died during follow-up. Propafenone and sotalol, 2 new antiarrhythmic agents, were found to be equally effective in maintaining sinus rhythm in 100 patients with recurrent AF. Response rates were not affected by arrhythmia pattern, left atrial size or unsuccessful prior drug therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of effects of propranolol versus pindolol on sinus rate and pacing frequency in sick sinus syndrome

Beta blockers in patients with sick sinus syndrome (SSS) may prevent supraventricular arrhythmias, systemic hypertension and myocardial ischemia, but may cause excessive depression of sinus node function. In 8 patients with SSS and a permanent pacemaker, the effect of chronic oral pindolol on sinus rate and pacing frequency was compared with that of propranolol in a double-blind crossover trial. In all patients the pacemaker was programmed to a rate of < or = 50 beats/min. Holter monitors, obtained at baseline and on each drug, were used to calculate peak ambulatory sinus rate, number of paced beats per day, maximal number of paced beats per hour, and percentage of hours with paced beats. The peak sinus rate with pindolol therapy was 24% higher than with propranolol (p = 0.001). During pindolol therapy, the number of paced beats per day and maximal paced beats per hour were reduced 54% (p = 0.04) and 61% (p = 0.02), respectively, compared with propranolol. Patients with SSS who require beta-blocker therapy for tachycardia, systemic hypertension or angina pectoris may have less bradycardia when treated with pindolol rather than propranolol. Beta blockers like pindolol, which cause less sinus node depression, may obviate the need for prophylactic permanent pacemakers in patients with SSS, and may help to prevent chronotropic incompetence and pacemaker syndrome in patients already treated with a VVI device.

Permanent AV block or modification of AV nodal function by selective AV nodal artery ethanol infusion

The acute and chronic effects of selective AV nodal artery ethanol infusion on AV nodal function was studied in 9 closed chest anesthetized dogs. Using standard percutaneous techniques of arterial catheterization, a 2.2 French infusion catheter was positioned in the AV nodal artery. Ten minute infusions into the AV nodal artery of 25%, 50%, or 100% ethanol in normal saline at rates of 0.5 mL/min acutely resulted in complete AV nodal block (AVB) in 5 dogs, 2:1 AV nodal block in 1 dog, and prolongation of AV nodal effective refractory period and/or Wenckebach cycle length in the remaining 3 dogs. One dog died with persistent complete AV block 1 week after the ethanol infusion. When restudied 4 weeks later, 7 of the 8 surviving dogs had persistent modification of AV nodal function, including complete AV block in 5 dogs and lengthening of AV nodal effective refractory period and/or Wenckebach cycle length without AV block in 2 dogs. Pathologic examination of the animals exhibiting chronic modification or ablation of AV nodal function revealed healing infarction of the AV node or its approaches. Distant myocardial necrosis was not observed and left ventricular function was normal. Slow infusion of low concentrations of ethanol into the AV nodal artery results in AV nodal modification or ablation due to localized necrosis in or around the AV node. This technique may have a role in AV nodal modification or ablation, particularly in patients who have failed DC shock or radiofrequency ablation.

Atrioventricular nodal reentrant tachycardia with retrograde block induced by aprindine

Two patients are described who had atrioventricular nodal reentrant tachycardia (AVNRT) with 1:1 relationship in the control state, but in whom a varying degree of VA block during AVNRT was observed during therapy with aprindine. Aprindine, however, did not cause anterograde blockade of conduction over the slow AV nodal pathway during tachycardia. These observations support the conclusion that the bulk of atrial muscle is not a requisite part of the tachycardia circuit in AVNRT and that antiarrhythmic drugs may have disparate effects on conduction in the retrograde and anterograde limbs of the circuit.

When should patients with lethal ventricular arrhythmia resume driving? An analysis of state regulations and physician practices

Most states have specific laws governing whether patients with seizure disorders can drive. To learn whether similar laws exist for patients with lethal ventricular arrhythmias, we surveyed the Departments of Motor Vehicles in all 50 states. In addition, either an arrhythmia specialist (n = 25) or a general cardiologist (n = 25) was chosen randomly from each state and interviewed to study physician awareness of such laws and physician attitudes toward driving by patients with arrhythmias. Forty-two states (84%) have laws restricting driving by patients who have seizures; only 8 states (16%) have specific laws for patients with arrhythmias. No state makes a distinction between driving by patients with arrhythmias who are managed with an implantable cardioverter-defibrillator (ICD) compared with patients who are managed medically. Seventy-four percent of physicians did not know their own state's laws about driving by patients who have ventricular arrhythmias. Cardiologists were more likely to advise no driving restriction for medically treated patients than for ICD-treated patients. Cardiologists were also more likely to advise permanent restriction for patients with ICDs than for patients treated medically. We conclude that greater legal and medical consensus is needed to guide physicians in advising patients with lethal ventricular arrhythmias about driving restrictions.

Time course of improvement in ventricular function after ablation of incessant automatic atrial tachycardia

A patient with dilated cardiomyopathy and supraventricular tachycardia presumed to be of sinus origin was referred for cardiac transplantation. The extreme rate of the tachycardia during exercise, profound fluctuations in heart rate, and the presence of an abnormal P wave axis suggested the diagnosis of incessant ectopic atrial tachycardia rather than compensatory sinus tachycardia. Electrophysiologic study with endocardial activation sequence mapping confirmed the diagnosis of an ectopic left atrial automatic tachycardia, after which surgical cryoablation of the left atrial focus was carried out successfully and sinus rhythm was restored. Serial radionuclide angiocardiograms obtained before and after surgery demonstrated a very rapid recovery of left ventricular function to nearly normal within the first month after surgery, followed by further improvement to normal over the next several months. The diagnosis of tachycardia-related cardiomyopathy should be seriously considered in any patient with apparently end-stage dilated cardiomyopathy and persistent resting tachycardia.

Suppression of incessant polymorphic ventricular tachycardia by selective intracoronary ethanol infusion

Two weeks after an extensive anterior myocardial infarction, a 68-year-old man developed incessant polymorphic ventricular tachycardia (PMVT), unresponsive to all conventional treatment modalities. After requiring greater than 40 direct current cardioversions in less than 3 hours, he underwent attempted intracoronary chemical ablation of his arrhythmia as a treatment of last resort. An infusion catheter was positioned selectively in the subtotally occluded left anterior descending (LAD) coronary artery, the putative "tachycardia-related vessel." Fifty percent ethanol was delivered to the anterior wall through this catheter by slow, constant infusion. Following selective intracoronary ethanol infusion, spontaneous, unprovoked episodes of PMVT ceased, despite discontinuation of all antiarrhythmic drugs. The LAD remained patent. Several days later, the patient underwent coronary artery bypass surgery and implantation of an implantable defibrillator, succumbing in the early postoperative period from recrudescent intractable ventricular fibrillation and cardiogenic shock. Slow intracoronary infusion of 50% ethanol does not cause abrupt vessel occlusion such as occurs after rapid injection of higher concentrations of ethanol. Selective intracoronary infusion of 50% ethanol may provide temporary lifesaving suppression of otherwise intractable polymorphic ventricular tachycardia.

Modification of human atrioventricular nodal function by selective atrioventricular nodal artery catheterization

The hypothesis that human atrioventricular (AV) nodal function can be modulated selectively with a new technique of AV nodal artery catheterization was tested in eight subjects referred for diagnostic cardiac catheterization or electrophysiological studies. Three patients had no history of arrhythmias. Three patients had supraventricular tachycardia (SVT) due to reentry confined to the AV node (AVNRT). One patient had SVT due to reentry over a concealed AV bypass tract (AVRT-CBT), and one patient had nonsustained ventricular tachycardia. In each subject, sinus cycle length, AH interval, HV interval, AV nodal effective refractory period (AVN-ERP), and Wenckebach paced cycle length were measured in a control state. A flexible infusion catheter was then positioned selectively in the AV nodal artery of each subject. Through this catheter, a constant infusion of 0.1 mg/min procainamide at a flow rate of 0.125 ml/min (n = 1) or 50 micrograms/min acetylcholine at a flow rate of 0.25 ml/min (n = 4) was administered. Electrophysiological parameters were determined again during selective AV nodal artery drug infusion and during infusion of saline at identical rates. Two subjects developed transient AV nodal block during selective AV nodal catheterization alone and did not receive an infusion of drug or saline. A stable position of the AV nodal artery catheter could not be achieved in one other subject, who also received no drug or saline. In the other five subjects, drug infusion caused an increase in AVN-ERP from a control value of 312 +/- 52 msec to a value of 543 +/- 228 msec (p less than 0.05) and an increase in Wenckebach paced cycle length from a control value of 360 +/- 47 msec to a value of 572 +/- 217 msec (p less than 0.05). These parameters were unchanged from control during selective saline infusion. In two patients with AVNRT, drug infusion abolished SVT by causing complete blockade of ventriculoatrial conduction as well as lengthening of anterograde AVN-ERP. In the patient with AVRT-CBT, drug infusion abolished SVT by preventing repetitive anterograde AV conduction. Saline had no effect on SVT inducibility. Selective AV nodal artery catheterization enables AV nodal function to be modulated exclusively. Delivery of ablative agents to the AV node by this technique may be useful in patients with refractory SVT.

Therapy of refractory symptomatic atrial fibrillation and atrial flutter: a staged care approach with new antiarrhythmic drugs

One hundred nine patients with recurrent episodes of symptomatic atrial fibrillation or flutter, or both, who had failed one to five previous antiarrhythmic drug trials were treated with propafenone and, subsequently, sotalol if atrial fibrillation recurred. The clinical profile of the study group was as follows: age 63 +/- 13 years, left atrial anteroposterior dimension 4.4 +/- 0.9 cm and left ventricular ejection fraction 57 +/- 14%. Paroxysmal atrial fibrillation occurred in 56 patients (51%) and chronic atrial fibrillation occurred in 53 patients (49%). After loading and dose titration phases were completed, the maintenance doses of drugs were 450 to 900 mg/day for propafenone and 160 to 960 mg/day for sotalol. Life table estimates of the duration of freedom from atrial fibrillation were constructed for each drug trial. The percent of patients free of recurrent symptomatic arrhythmia at 6 months was 39% for propafenone and 50% for sotalol. The cumulative proportion of patients successfully treated with propafenone or sotalol, or both, by 6 months was 55% and remained relatively constant beyond that point. The incidence of intolerable side effects necessitating discontinuation of therapy ranged from 7% to 8%. Thus, despite previous unsuccessful drug trials, a substantial proportion of patients with recurrent symptomatic atrial fibrillation refractory to conventional therapy can be treated successfully and safely with newer antiarrhythmic drugs. Treatment failures tend to occur early in the course of follow-up, permitting easy identification of candidates for alternative therapeutic approaches.

Modification of atrioventricular conduction by selective AV nodal artery catheterization

The effects of selective AV nodal artery embolization on AV nodal function was investigated in six closed-chest adult dogs. Programmed atrial stimulation was performed to determine control values for AV nodal effective refractory period (AVN-ERP) and the paced cycle length at which AV nodal Wenckebach conduction occurred (WCL). Using standard percutaneous femoral techniques of coronary artery catheterization, a flexible infusion catheter was positioned selectively in the AV nodal artery. Proper positioning of the catheter was confirmed angiographically and by selective acetylcholine (ACH) infusion into the AV nodal artery, which caused transient complete AV nodal block in three dogs, and for the group, caused lengthening of both AVN-ERP and WCL. Following cessation of ACH infusion and autonomic blockade with atropine 0.04 mg/kg and propranolol 0.2 mg/kg, denervated recontrol values for AVN-ERP and WCL were 192 msec and 243 msec, respectively. The AV nodal artery was then embolized with a suspension of cross-linked collagen fibrils in either normal saline or absolute ethanol. Successful embolization of the AV nodal artery, confirmed angiographically, caused an acute increase in AVN-ERP (243 msec, P less than 0.05 compared to denervated control) and WCL (287 msec, P = 0.058 compared to denervated control). However, at a mean follow-up of 37 days, only one animal exhibited a chronic increase in AVN-ERP and WCL. Selective AV nodal artery catheterization can be performed using standard percutaneous catheterization techniques. Selective administration of agents with direct cidal effects on the AV node using this technique may provide an alternative to conventional methods of catheter ablation of AV conduction in patients with drug-resistant supraventricular arrhythmias.

Effect of selective intracoronary antiarrhythmic drug administration in sustained ventricular tachycardia

The effect of selective intracoronary antiarrhythmic drug infusion on inducibility of cardiac arrhythmias was studied in 3 patients with recurrent sustained monomorphic ventricular tachycardia referred for comprehensive electrophysiologic studies. Each patient had evidence of prior myocardial infarction, 1 or more occluded coronary arteries and a readily identifiable collateral vessel that provided collateral flow to the infarct-related artery. In each patient, the clinical arrhythmia was reproducibly inducible by programmed stimulation in the control state. After positioning a small infusion catheter in the collateral vessel, selective intracoronary lidocaine 0.3 to 0.6 mg/min (patients 1 and 2) or procainamide 0.1 to 1.4 mg/min (patient 3) was infused for a 10-minute period. In each patient the clinical arrhythmia was rendered noninducible during selective intracoronary drug infusion. The arrhythmia was again inducible after a 10-minute drug-washout period and also after standard intravenous doses of antiarrhythmic drug. Selective intracoronary antiarrhythmic drug infusion may help to localize the site of origin of some cardiac arrhythmias, may provide a means of testing the effects of several drugs during a single study and may be a new method for studying mechanisms of action of antiarrhythmic drugs.

"Clockwise" and "counterclockwise" bundle branch reentry as a mechanism for sustained ventricular tachycardia masquerading as supraventricular tachycardia

A 35-year-old man presented with a regular tachycardia having a typical right bundle branch block morphology. Electrophysiological testing revealed inducible tachycardia exhibiting counterclockwise as well as clockwise bundle branch reentry, leading to left and right bundle branch block morphologies. The disappearance of spontaneous episodes of these tachycardias following resolution of right bundle branch block in the resting electrocardiogram suggested that slow conduction in the right bundle branch played an essential role in the tachycardia circuit.

Caudal-posteroanterior view in coronary arteriography

Posteroanterior (PA) and caudally angulated PA views were obtained in 20 patients undergoing routine coronary arteriography. Although the left main coronary artery (LMCA) was seen well on both views in all patients, the PA-caudal view improved depiction of the LMCA bifurcation in 15 (75%). In addition, the PA-caudal view markedly improved depiction of the circumflex artery, affording optimal depiction of this artery and its branches in 78%-89% of patients. Neither the PA nor the PA-caudal view allowed adequate depiction of the left anterior descending artery. Thus, the PA-caudal view should supplant the PA view in routine coronary arteriography.