Unusual Features of Right and Left Idiopathic Ventricular Tachycardia Aholished hy Radiofrequency Catheter Ablation

Two unusual cases are presented with idiopathic right and left ventricular tachycardia(IVT) with intriguing clinical and electrophysiological characteristics. The first patient with a sustained IVT of right ventricular outflow tract origin, and an electrophysiological mechanism suggesting reentry, had been resuscitated from cardiac arrest. The second patient had an IVT with a left bundle branch block morphology, which originated from the basal-septal region of the left ventricle(left ventricular outflow tract tachycardia). Both patients were cured with radiofrequency catheter ablation, guided by endocardial activation sequence and pace mapping.     

Effects of Coronary Artery Bypass Grafting on Ventricular Arrhythmias: Results with Electrophysiological Testing and Long-Term Follow-Up

Myocardial revascularization was performed in 56 patients with coronary artery disease who presented with ventricular tachycardia (VT) (n = 39) or ventricular fibrillation (n = 17). There were 46 men and 10 women, aged 65 ± 10 years. Three vessel (n = 42) or left main disease (n = 4) was present in 82%. Left ventricular ejection fraction averaged 36%± 11%. Electrophysioiogical studies were performed preoperatively in all patients; 50 (89%) had inducible ventricular arrhythmias. Sustained monomorphic VT was induced in 40 patients (cycle length 284 ± 61 msec). Reproducible symptomatic nonsustained VT was induced in four patients and ventricular fibrillation in six patients, while six patients had no inducible arrhythmia. Preoperatively the patients with inducible VT failed 3.3 ± 1.2 drug trials during electrophysiological studies. In addition to coronary bypass, 22 patients also received an automatic implantable cardioverter defibrillator (ICD), 26 patients received prophylactic ICD patches, and 1 patient had resection of a false aneurysm. There were no perioperative deaths. Postoperative electrophysiological studies were performed in all 56 surgical survivors. Ventricular tachyarrhythmia could not be induced in the six patients who had no inducible VT preoperatively and in 13 of 40 (33%) with preoperatively inducible sustained VT or in 19 of 50 (38%) patients with any previously inducible ventricular arrhythmia, thus a totaJ of 25 patients (45%) had no inducible VT postoperatively. Of the remaining, 11 patients were treated with antiarrhythmic drugs alone, 11 had already received an ICD (combined with drugs in 7), and another 9 received the ICD postoperatively (combined with drugs in 4). At a mean foJJow-up of 28 ± 21 months there were 11 deaths (20%): 2 sudden, 5 nonsudden cardiac, and 4 noncardiac deaths. There were 16 nonfatal VT recurrences (29%): 14 among patients with persistently inducible arrhythmias, and onJy 2 among those with no inducible arrhythmia postoperatively (P = 0.004); 13 occurred in patients with an ICD (P = 0.01). Thus among these patients with malignant ventricular arrhythmias who underwent revascuJarization, 45% had no inducible arrhythmia postoperatively with 33% of those with preoperatively inducible sustained VT apparently rendered noninducible by revascularization, while the majority (70%) remained free of major arrhythmic events during long-term follow-up. We conclude that myocardial revascularization alone can result in no ventricular arrhythmia induction in selected patients with VT inducible prior to surgery. Long-term follow-up of such patients indicates a low sudden death and arrhythmia recurrence rate. Furthermore, in patients with persistently inducible ventricular tachyarrhythmias after coronary revascuJarization, the sudden death rate is low despite a high frequency of nonfatal arrhythmia recurrence when antiarrhythmic medications are guided by programmed stimulation or an ICD is used.     

CGMP Levels Following ANF Challenge are Markers of Subsequent Successful Reversion of Lone Atrial Fibrillation to Sinus Rhythm

The aim of the present study was to assess whether cGMP release to ANP stimulation can be a biochemical marker of subsequent successful electrical cardioversion of lone atrial fibrillation to sinus rhythm. For this purpose, we studied 13 patients with chronic, lone atrial fibrillation of less than one year's duration who presented to our laboratory for electrical therapy of their arrhythmia. Prior to electrical cardioversion, peripheral venous cGMP levels were assessed at baseline and following an tntravenous challenge of 50 Ug human ANP. Venous blood samples for cGMP assessment were taken a) at baseline, b) 5 and 10 mins after the end of ANP infusion. ANOVA of repeated measures was used for statistical analysis. Eight of the study patients were successfully cardioverted to sinus rhythm, while the remaining 5 were not. Although no difference was noted between the two groups regarding the mean time of arrhythmia duration as well as left atrial and ventricular dimensions, ANP stimulation provoked significantly greater cGMP release in patients whose arrhythmia reverted to sinus rhythm, when compared with that of patients whose arrhythmia persisted (p<0.001). Therefore, cGMP levels following ANP challenge might discriminate between patients with chronic AF who are going to be successfully cardioverted and those who are not. These findings imply that the underlying atrial disease might be different in extent/nature between patients with lone AF responsive to cardioversion and those with resistant arrhythmia.     

Inappropriate Shocks and Elevation of Defibrillation Thresholds in a Patient with Automatic Defibrillator Patch Silastic Erosion and Titanium Mesh Fraying

A case is presented of a defibrillator patch erosion, inappropriate shocks, and high defibrillation thresholds in a 59-year-old man requiring thoracotomy for proper diagnosis and management.     

Exercise and Arrhythmias: A Double‐Edged Sword

Ample evidence indicates that moderate regular exercise is beneficial for both normal individuals and patients with cardiovascular (CV) disease. However, intense and strenuous exercise in individuals with evident or occult underlying CV abnormalities may have adverse effects with provocation and exacerbation of arrhythmias that may lead to life‐threatening situations. Both of these aspects of exercise‐induced effects are herein reviewed.     

The Effect of DDD Pacing on Ergospirometric Parameters and Neurohormonal Activity in Patients with Hypertrophic Obstructive Cardiomyopathy

This study examined the acute and long-term effects of DDD pacing on ergospirometric parameters and neurohormonal activity in patients with hypertrophic obstructive Cardiomyopathy (HOCM). We studied eight patients (five males), aged 56 ± 7 years, with HOCM refractory to drugs. In all patients a DDD pacemaker was implanted and programmed with an atrioventricular (AV) delay that insured full ventricular activation. The patients underwent echocardiographic examination and exercise stress testing before and 3 days, 3 months, and 12 months after pacemaker implantation. Oxygen consumption was measured at the anaerobic threshold (VO_2AT) and peak exercise (pVO₂). Atrial natriuretic peptide (ANP) and cyclic adenosine monophosphate (c-AMP) levels were measured concomitantly. Left ventricular outflow tract (LVOT) pressure gradient decreased significantly from 70 ± 18 to 25 ± 12 mmHg (P < 0.05) 3 days after pacing and remained unchanged at 3 and 12 months. pVO₂ and VO_2AT increased significantly, from 20.1 ± 3 to 23.4 ± 3 mL/kg/min and from 16 ± 3 to 17.8 ± 2 mL/kg/min, respectively (P < 0.05). This improvement continued up to 3 months, and then remained stable until the end of the 12-month follow-up period. ANP levels decreased at 3 days from 85.4 ± 5.7 to 75.4 ± 7.3 fmol/mL (P < 0.05), and remained unchanged over the 12 months. c-AMP levels did not change significantly after the onset of pacing. DDD pacing in patients with HOCM not only reduces the LVOT pressure gradient but also causes a significant early and long-term improvement in exercise capacity and neurohormonal profile.     

Arrhythmogenic Right Ventricular Cardiomyopathy in an Octogenarian Presenting with Ventricular Tachycardia

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is one of the major causes of sudden death. Myocardial atrophy with subsequent fibro‐fatty replacement predominantly affects right ventricular myocardium and results in global and regional dysfunction as well as areas of slow conduction and dispersion of refractoriness, which are prerequisites for reentrant ventricular tachyarrhythmias. ARVC is commonly presented in patients <65 years old. However, few cases of elderly people suffering from this cardiomyopathy have been reported in the literature. We present a case of an 82‐year‐old woman with sustained ventricular tachycardia due to first diagnosed ARVC.     

Vein plasma endothelin-1 and cyclic GMP increase during coronary angioplasty is related to myocardial ischaemia

Endothelin-1 and cyclic guanosine monophosphate (c-GMP) peripheralvein plasma levels increase during coronary angioplasty, butthe reason for this increase has not been elucidated. The purposeof this study was to investigate whether these changes are relatedto myocardial ischaemia, or to mechanical artery injury inducedduring the procedure. Thirty-two patients with stable anginapectoris and a single lesion were studied. They were aged 56±8 and were undergoing balloon angioplasty. Eight arterieswere totally occluded and 24 were partially occluded. Bloodsamples were drawn from a peripheral vein after coronary arteryengagement with the guiding catheter (baseline), after the firstballoon inflation, immediately after the end of the procedure,and 4 h later.In the total occlusion group endothelin-1 increasedby 7% (P ns), whereas in the partial occlusion group it increasedby 45% after the procedure (P<0.001). c-GMP in the partialocclusion group increased by 41% (P<0.001) after the procedurewhereas in the total occlusion group it increased by 5% (P ns).Thus, the increase in endothelin-1 and c-GMP peripheral veinplasma levels after coronary angioplasty is related to myocardialischaemia rather than to mechanical artery injury.