The intravenous adenosine test: a new test for the identification of bradycardia pacing indications? A pilot study in subjects with bradycardia pacing indications, vasovagal syncope and controls.

BACKGROUND: Intravenous adenosine has recently been used in the diagnosis of unexplained syncope, but there is no consensus as to the meaning of a 'positive' test. The objective is to determine the sensitivity and specificity of intravenous adenosine testing in the diagnosis of bradycardia-pacing indications [sinus node dysfunction(SND), atrio-ventricular block (AVB) and cardio-inhibitory carotid sinus syndrome (CSS)]. DESIGN: Pilot cohort study. METHODS: Patients-(i) Bradycardia-pacing group: Consecutive patients referred for pacing for SND, AVB and CSS; (ii) Consecutive head-up tilt (HUT)-positive VVS patients. Controls-(i) Simple controls (S-Con: normal examination/ECG) and (ii) Electrophysiology controls (EP-Con: consecutive subjects referred for accessory pathway ablation). Pacing referrals and EP-Con had electrophysiology studies to confirm referral diagnosis and exclude others. All subjects had bolus injection of 20 mg intravenous adenosine during continuous ECG and blood pressure monitoring (positive test: >or=6 s asystole, >or=10 s high-degree AVB post-injection). Sensitivity, specificity, safety and tolerability of the test were measured. RESULTS: Of 264 potential participants (4 SND, 8 AVB, 7 CSS, 10 VVS, 10 EP-Con and 11 S-Con) 50 were studied. All (100%) of the bradycardia-pacing group were adenosine test-positive, as were 6 (60%) VVS. None (0%) and 3 (27%) of the EP- and S-Con groups were positive. Adenosine testing was 100% sensitive and 86% specific for bradycardia-pacing indications, and 100% specific using the diagnostically 'clean' EP-Con results. There were no significant adverse or side effects. CONCLUSION: Adenosine testing reliably identified patients with definitive bradycardia-pacing indications in whom alternative diagnoses were excluded. Further work is needed to evaluate the role of this test in the diagnosis of unexplained syncope.

Pacing to restore right ventricular contraction after surgical disconnection for arrhythmia control in right ventricular cardiomyopathy.

Ventricular tachycardia in ARVC (arrhythmogenic right ventricular cardiomyopathy) is typically managed by ICD implantation, with a limited role of catheter ablation. Surgical disconnection of the right ventricular (RV) has been used to control ventricular tachycardia (VT) in ARVC, but it often led to refractory RV failure due to loss of RV contraction after surgery. We report multisite pacing to recruit the disconnected RV to prevent ventricular failure.

Pulmonary vein ablation for idiopathic atrial fibrillation: six month outcome of first procedure in 100 consecutive patients.

OBJECTIVES: To report six month outcome in patients undergoing their first pulmonary vein ablation procedure for idiopathic atrial fibrillation (AF) at a "non-pioneering" hospital. DESIGN: Prospective observational study. SETTING: Specialist electrophysiology unit at a university hospital. PATIENTS: The first 100 consecutive patients undergoing their first pulmonary vein catheter ablation procedure for highly symptomatic, drug resistant AF in the period 1999-2002. MAIN OUTCOME MEASURES: Incidence of symptomatic or asymptomatic, Holter documented AF six months after ablation. RESULTS: Mean patient age was 52 years (range 23-73 years), mean length of AF history 53 months (range 6-180 months), mean number of antiarrhythmic drug failures was 3 (range 1-5), and 81 were men. At the time of the ablation procedure, 64 had progressed to persistent AF and 23 had increased transverse left atrial diameter. The number of pulmonary veins ablated in each patient was one in 11, two in 45, three in 36, and four in 8. Six months after ablation, 55 patients were consistently in sinus rhythm, asymptomatic, and without any Holter evidence of AF. The chance of being in sinus rhythm was 73% (29 of 64) in those with paroxysmal as compared with only 45% (26 of 36) in those with persistent AF at the time of ablation (p = 0.01). Outcome was not influenced by patient age, length of AF history, or duration of persistent AF before ablation or to left atrial dimension. Follow up was complete and no patient has died or experienced a stroke during or after ablation; nor have any developed symptoms of late pulmonary vein stenosis. However, other complications occurred during or shortly after the procedure in 12 patients, including cardiac tamponade in six. CONCLUSIONS: In selected patients with drug resistant AF, focal pulmonary vein catheter ablation offers a realistic prospect of achieving stable sinus rhythm compared with alternatives. However, it is a complex form of ablation with a significant risk of serious complications. Although a new milestone in arrhythmia management, the optimum ablation technique is still evolving and any impact on the natural history of AF remains to be determined.

Rapid intravenous administration of granisetron prior to chemotherapy is not arythmogenic: results of a pilot study.

Patients with advanced malignancy are at an increased risk of cardiac arrhythmias, from their cancer and cardiotoxic treatments. Supportive care products co-administered should therefore not increase this risk. No clinically important cardiovascular effects are associated with the administration of granisetron over 30 s. To determine the effects of a rapid (1 s) injection of granisetron, 3 mg, on measures of cardiac repolarisation, a pilot study was performed in 17 patients undergoing moderately/highly emetogenic chemotherapy at two centres. All received dexamethasone, 8-12 mg, infused over 30 min, followed immediately by granisetron and then chemotherapy. Twelve-lead electrocardiograms (ECGs) performed before granisetron treatment, 2 h later and the following day (11 patients) showed no differences in QTc(end max), QTc(apex max) or QT-interval dispersion between baseline and subsequent measurements, and there were no significant secondary adverse events. On this basis, granisetron should be considered the first-choice antiemetic for patients at increased risk of cardiac complications.

Radiofrequency ablation for post infarction ventricular tachycardia. Report of a single centre experience of 112 cases.

OBJECTIVES: This report presents the largest consecutive series to date of radiofrequency ablation in the treatment of post infarction ventricular tachycardia. METHODS: One hundred and twelve consecutive patients were studied, with an average of 12 documented episodes of ventricular tachycardia in the month preceding the radiofrequency ablation. Seventy-four percent of the subjects had an ejection fraction of less than 35%; 84% had more than one morphology of ventricular tachycardia and 30% had haemodynamically unstable ventricular tachycardia. The mean follow-up period was 61 months. RESULTS: Complete success defined as no inducible sustained monomorphic ventricular tachycardia was achieved in 38%. Modified result, defined as ventricular tachycardia only inducible by two stimuli more aggressive than at baseline was achieved in 34%. During follow-up, ventricular tachycardia recurred in 25 patients: 22 after a failed procedure, two following a modified result and one following a complete success. Twenty-five patients died: 13 of progressive cardiac failure and four of presumed arrhythmic causes, three after a failed procedure and one following a modified result. There were no procedure-related deaths. Procedural complications occurred in seven patients. CONCLUSIONS: In this report, radiofrequency ablation of post infarction ventricular tachycardia is a successful procedure with a low complication rate. Acute procedural success accurately predicts long-term freedom from recurrent ventricular tachycardia.

Observation of magnetic coupling between distant metal centers in K3(MnO4)2 by muon spin relaxation measurements.

The site of a probe muon in the double salt K3(MnO4)2, which exhibits an antiferromagnetic phase at low temperature, and the Néel temperature of the salt were determined by zero-field muon spin relaxation. The picture shows the relaxation of the polarization asymmetry after muon insertion and a part of the crystal lattice.

Radiofrequency ablation of haemodynamically unstable ventricular tachycardia after myocardial infarction.

OBJECTIVE: To determine whether radiofrequency (RF) ablation might have a role in haemodynamically unstable ventricular tachycardia. METHODS: 10 patients with a history of ventricular tachycardia producing haemodynamic collapse in whom drug treatment had failed and device therapy was rejected underwent RF ablation of ventricular tachycardia in sinus rhythm. The arrhythmogenic zone was defined on the basis of abnormal systolic movement, the presence of fragmentation (low amplitude, prolonged multiphasic electrograms), and pace mapping. RF lesions were delivered in power mode in linear fashion within the defined arrhythmogenic zone. RESULTS: Success (no ventricular tachycardia inducible postablation or at retest) was achieved in six patients, possible success (a different ventricular tachycardia inducible at more aggressive stimulation) in three. In one patient, the procedure was abandoned because of poor catheter stability. There were no clinical events during a mean (SD) follow up period of 23 (10) months in any of the nine patients defined as definite or possible successes. CONCLUSIONS: RF ablation for addressing haemodynamically unstable ventricular tachycardia opens the door for the wider use of catheter ablation for treating this arrhythmia.

Reduction of symptoms from LVOT tachycardia following inadvertent fast pathway ablation.

VT was mapped to above the aortic valve in a young patient with troublesome palpitations. A single 15-second RF application was inadvertently delivered to a reference His catheter producing permanent first-degree heart block. The patient has been completely asymptomatic since.

Thoracoscopic mapping and cryoablation of right ventricular tachycardia.

A 14-year-old girl with right ventricular dysplasia and recurrent drug refractory ventricular tachycardia underwent thoracoscopic mapping cryoablation. Good access to the right ventricular free wall was obtained. We suggest this technique may have an important role in the management of patients with right ventricular tachycardia.

Effects of surgery for postinfarction ventricular tachycardia on parameters of left ventricular function.

Heart failure is the leading cause of death in patients after surgery for ventricular tachycardia. This study examines the effects of antiarrhythmic surgery on 4 parameters of left ventricular (LV) function. Global ejection fraction, segmental wall motion score, homogeneity of contraction, and diastolic function were measured in 32 patients by technetium-99m radionuclide ventriculography. Ejection fraction was measured from the left anterior oblique image. Wall motion score was assessed semiquantitatively for 11 LV segments from 3 projections. Homogeneity of contraction was expressed as the SD of the LV phase analysis curve during systole from the left anterior oblique image. Diastolic function was expressed in terms of peak and mean first time derivative of the action potential (dV/dt) of the LV function curve. Subgroup analyses were performed to distinguish the effects of aneurysmectomy, coronary artery bypass grafting, and changes in angiotensin converting enzyme inhibitor therapy. Mean systolic function improved after surgery (ejection fraction 22% vs 32%, p <0001; wall motion score 20 vs 13, p <0.0001; phase analysis 18 vs 12, p <0.03). Mean diastolic function also improved (peak dV/dt 0.83 +/- 0.32 vs 1.49 +/- 0.39, p = 0.006; mean dV/dt 0.41 +/- 0.15 vs 0.76 +/- 0.27, p = 0.006). Improvements were not confined to those who had aneurysmectomy or coronary bypass grafting and were not explained by changes in vasodilator therapy. Thus, antiarrhythmic surgery does not inherently damage LV function. Significant improvements were observed in most patients. Failure to improve indicated a poor longer term prognosis.

Surgery for postinfarction ventricular tachycardia in the pre-implantable cardioverter defibrillator era: early and long term outcomes in 100 consecutive patients.

OBJECTIVE: To report outcome following surgery for postinfarction ventricular tachycardia undertaken in patients before the use of implantable defibrillators. DESIGN: A retrospective review, with uniform patient selection criteria and surgical and mapping strategy throughout. Complete follow up. Long term death notification by OPCS (Office of Population Censuses and Statistics) registration. SETTING: Tertiary referral centre for arrhythmia management. PATIENTS: 100 consecutive postinfarction patients who underwent map guided endocardial resection at this hospital in the period 1981-91 for drug refractory ventricular tachyarrhythmias. RESULTS: Emergency surgery was required for intractable arrhythmias in 28 patients, and 32 had surgery within eight weeks of infarction ("early"). Surgery comprised endocardial resections in all, aneurysmectomy in 57, cryoablations in 26, and antiarrhythmic ventriculotomies in 11. Twenty five patients died < 30 days after surgery, 21 of cardiac failure. This high mortality reflects the type of patients included in the series. Only 12 received antiarrhythmic drugs after surgery. Perioperative mortality was related to preoperative left ventricular function and the context of surgery. Mortality rates for elective surgery more than eight weeks after infarction, early surgery, emergency surgery, and early emergency surgery were 18%, 31%, 46%, and 50%, respectively. Actuarial survival rates at one, three, five, and 10 years after surgery were 66%, 62%, 57%, and 35%. CONCLUSIONS: Surgery offers arrhythmia abolition at a risk proportional to the patient's preoperative risk of death from ventricular arrhythmias. The long term follow up results suggest a continuing role for surgery in selected patients even in the era of catheter ablation and implantable defibrillators.

Identifying patients at low risk of death from cardiac failure after operation for postinfarct ventricular tachycardia.

BACKGROUND: In unselected patients, cardiac failure accounted for most deaths after antiarrhythmic operation (ER) for postinfarction ventricular tachycardia (VT). This study aimed to determine whether patients at low risk of this outcome could be predicted from a retrospective analysis of variables from 100 consecutive ER patients. METHODS: Thirteen variables suggested by other researchers as predictive of outcome were analyzed. At the time of study, ER was the only therapy available for drug refractory VT. RESULTS: Only emergency ER, wall motion score less than 3 and Killip classification were significantly related to death from cardiac failure. The lack of correlation between emergency ER and variables of ER timing, VT less than 24 hours of ER or VT type implies that the need for emergency ER is also related to ventricular dysfunction. Multivariate analysis identified a group at particularly low risk of death with a specificity of 95%. CONCLUSIONS: Patients at low risk of death after ER can be identified prospectively. In the implantable cardioverter defibrillator era, elective ER is best reserved for such patients. Emergency ER may still be justified in younger patients without comorbidity who will die of VT without it.

The safety of dipyridamole-thallium imaging in patients with critical aortic valve stenosis and angina.

Angina pectoris occurs in many patients with critical aortic valve stenosis, but in less than 50% of cases is it due to atherosclerotic coronary disease. Pre-operative coronary angiography is used to determine whether coronary revascularization is required in addition to aortic valve replacement. The aim of this study was to determine the safety and image quality of dipyridamole-thallium imaging (DPT) in excluding coronary artery disease requiring a coronary artery bypass graft in patients with aortic valve stenosis requiring aortic valve replacement. Dipyridamole-thallium imaging and coronary angiography were performed less than one month apart in patients with clinical and echo-Doppler evidence of aortic valve stenosis requiring aortic valve replacement. Coronary angiography and DPT were each interpreted by experienced observers blind to the other result. The safety of DPT was judged by symptoms, ECG changes, haemodynamic effects and the need for stress reversal. Image quality was determined from the myocardial-to-background thallium uptake ratio in a normal segment. Twelve patients with aortic valve stenosis (gradient 95 +/- 24 mmHg) were studied, all of whom had left ventricular hypertrophy. The dominant symptom was angina pectoris in eight patients, syncope in three and dyspnoea in one. None had previous myocardial infarction, but two were smokers, six were hyperlipidaemic and one was hypertensive. The patients tolerated DPT well and only one required stress reversal. The quality of the DPT images was good. The DPT image was entirely normal in eight (66%) patients, none of whom had coronary artery disease. Reversible defects were seen in four patients, all of whom had significant coronary artery disease. We conclude that DPT is safe in patients with aortic valve stenosis and angina pectoris. The image quality is good despite left ventricular hypertrophy. In patients with angina pectoris and aortic valve stenosis, coronary angiography can safely be restricted to those with abnormal myocardial perfusion results.

Survival in a case of life-threatening flecainide overdose.

Flecainide acetate is a potent class Ic anti-arrhythmic drug with major sodium channel blocking actions. On the surface electrocardiogram this results in QTc interval prolongation. Overdose with class Ic drugs (< 0.1% of total intoxications) is uncommon, but management is difficult and the mortality high [1]. Serious flecainide overdose is characterised by ventricular tachyarrhythmias, severe bradycardia and variable degrees of atrioventricular block. This report describes a case of life-threatening flecainide overdose in a previously fit individual, resulting in a combination of cardiac disturbances. The treatment options and management are discussed.

Role of orthotopic heart transplantation in the management of patients with recurrent ventricular tachyarrhythmias following myocardial infarction.

OBJECTIVE: To report the outcome of an intention to treat by heart transplantation strategy in two groups of patients after infarction, one with both left ventricular failure (LVF) and ventricular tachyarrhythmias (VTA) (group A) and the other with progressive LVF following antiarrhythmic surgery for VTA (group B). PATIENTS AND METHODS: Group A comprised 17 consecutive patients for whom transplantation was considered the best primary non-pharmacological treatment; group B comprised five consecutive patients assessed and planned for transplantation after antiarrhythmic surgery. RESULTS: In group A, eight patients underwent transplantation and all survived the first 30 day period. At median follow up of 55 months (range 11 to 109) seven of this subgroup were still alive. Five patients died of recurrent VTA before transplantation, despite circulatory support. In the face of uncontrollable VTA, four of these underwent "high risk" antiarrhythmic surgery while awaiting transplantation: three died of LVF within 30 days and one was saved by heart transplantation two days after arrhythmia surgery. Mortality for the transplantation strategy in group A patients was 47% by intention to treat analysis. Quality of life in the eight actually transplanted, however, was good and only one died during median follow up of 56 months. The five patients in group B were accepted for transplantation for progressive LVF at a median of 21 months (range 12 to 28) after antiarrhythmic surgery. One died of LVF before transplantation, 22 months after initial surgery; another died of high output LVF three days after transplantation. Thus mortality of the intended strategy was 40%. The three transplanted patients are alive and well at 8-86 months. CONCLUSIONS: Although the short and medium term outcome in category A or B patients who undergo transplantation is good, the overall success of the transplantation strategy in category A patients is limited by lack of donors in the short time frame in which they are required.

Predictors of atrial rhythm after atrioventricular node ablation for the treatment of paroxysmal atrial arrhythmias.

OBJECTIVE: To assess the natural history of the atrial rhythm of patients with paroxysmal atrial arrhythmias undergoing atrioventricular node ablation and permanent pacemaker implantation. DESIGN AND SETTING: A retrospective cohort study of consecutive patients identified from the pacemaker database and electrophysiology records of a tertiary referral hospital. PATIENTS: 62 consecutive patients with paroxysmal atrial arrhythmias undergoing atrioventricular node ablation and permanent pacemaker implantation between 1988 and July 1996. MAIN OUTCOME MEASURES: (1) Atrial rhythm on final follow up ECG, classified as either ordered (sinus rhythm or atrial pacing) or disordered (atrial fibrillation, atrial flutter or atrial tachycardia). (2) Chronic atrial fibrillation, defined as a disordered rhythm on two consecutive ECGs (or throughout a 24 hour Holter recording) with no ordered rhythm subsequently documented. RESULTS: Survival analysis showed that 75% of patients progressed to chronic atrial fibrillation by 2584 days (86 months). On multiple logistic regression analysis a history of electrical cardioversion, increasing patient age, and VVI pacing were associated with the development of chronic atrial fibrillation. A history of electrical cardioversion and increasing patient age were associated with a disordered atrial rhythm on the final follow up ECG. CONCLUSIONS: Patients with paroxysmal atrial arrhythmias are at high risk of developing chronic atrial fibrillation. A history of direct current cardioversion.

Right ventricular disarticulation procedures: the role of late potentials in the genesis of postoperative ventricular arrhythmias.

Arrhythmogenic right ventricular disease may be associated with life-threatening and drug refractory ventricular arrhythmias. Right ventricular disarticulation procedures are effective antiarrhythmic surgical approaches in selected patients. This study examined the role of late potentials in the postoperative development of new ventricular arrhythmias, and showed that right ventricular isolation is effective, probably because it destroys the tissue giving rise to late potentials. Total disarticulation is associated with fewer postoperative arrhythmias than partial isolation procedures. Total disarticulation may be the surgical approach of choice in such patients.