Impact of amiodarone on electrophysiologic properties of pulmonary veins in patients with paroxysmal atrial fibrillation

INTRODUCTION: Pulmonary veins (PVs) are the predominant location of triggers for atrial fibrillation (AF), but little is known about the electrophysiologic properties of PVs. In addition, the influence of amiodarone on the electrophysiologic properties of PVs has not been elucidated. METHODS AND RESULTS: Fifty-five patients with symptomatic and drug-resistant AF were divided into two groups: group 1 patients (n=29) without antiarrhythmic drug therapy at the time of electrophysiologic study (EPS), and group 2 patients (n=26) undergoing continuous long-term treatment with amiodarone. EPS including programmed stimulation of both atria and within the PVs was performed in both groups. In group 1, the effective refractory period (ERP) of all PVs (174 +/- 62 msec) was significantly shorter than the ERP of the left atrium ([LA] 254 +/- 30 msec, P=0.0001) and right atrium ([RA] 221 +/- 29 msec, P=0.0001). The same pattern was observed in group 2 (PV: 210 +/- 58 msec; LA: 259 +/- 35 msec, P=0.0001; RA: 246 +/- 37 msec, P=0.0255). The ERP of all stimulated PVs was significantly lower in group 1 (174 +/- 62 msec) than in group 2 (210 +/- 58 msec; P=0.0001). The ERP of the left superior and right superior PVs and RA but not the left inferior PV and LA were significantly increased in patients treated with amiodarone. Decremental conduction properties were observed in all stimulated PVs, and there were no significantly differences between the maximal decrement of both groups. CONCLUSION: The distinctive electrophysiologic properties of PVs are emphasized by amiodarone therapy. Long-term amiodarone treatment is responsible for heterogeneous alteration of the PV electrophysiology, which may account for the individual antiarrhythmic responses in a subset of patients with paroxysmal AF.     

Echocardiographic advances in atrial fibrillation and supraventricular arrhythmias

Advances in echocardiography have paved the way for the development of intracardiac catheters with ultrasound transducers mounted on its tip. With this technology it has become possible for the interventional electrophysiologist to perform continuous echocardiographic examination during a procedure without the need for general anaesthesia or additional staff. Intracardiac echocardiography (ICE) allows the monitoring of catheter movement in real-time, assessment of catheter-tissue contact and potentially prevents and recognizes complications like thrombus formation and pericardial effusion. In addition recent technologies allow acquiring the full spectrum of Doppler-imaging permitting evaluation of haemodynamic data during the procedure. All these advances have made ICE an ideal tool for the interventional electrophysiologist, serving as a diagnostic and imaging tool during invasive electrophysiological procedures. This review will summarize currently available technology of ICE and its indications and applications in electrophysiological procedures.     

Substrate modification combined with pulmonary vein isolation improves outcome of catheter ablation in patients with persistent atrial fibrillation: a prospective randomized comparison.

AIMS: To investigate the effectiveness of additional substrate modification (SM) by left atrial (LA) linear lesions as compared with pulmonary vein isolation (PVI) alone in patients with persistent atrial fibrillation (AF) in a prospective randomized study. Percutaneous PVI has evolved as an accepted treatment for paroxysmal AF but seemed to be less effective in patients with persistent AF. The benefit of PVI alone and additional linear lesions has not been validated in a randomized study so far. METHODS AND RESULTS: Sixty-two patients with persistent AF (median duration 7, range 1-18 months) were randomly assigned to either PVI alone (n = 30) or additional SM (n =32) consisting of a roof line connecting both left superior and right superior PV and LA isthmus ablation between left inferior PV and mitral annulus. Procedures including SM were performed using a three-dimensional mapping system (EnSite NavX, St Jude Medical, St Paul, MN, USA). Anti-arrhythmic drugs were discontinued within 8 weeks after ablation in both groups. Follow-up included daily trans-telephonic ECG transmitted irrespective of the patient's symptoms. PVI was successful in 98% of all targeted veins in both groups. Additional SM did not increase fluoroscopy time (72.1+/-18.7 vs. 72.9+/-17.3 min, P=0.92) because of the use of three-dimensional navigation in the PVI+SM group. AF recurrences within the first 4 weeks following ablation were more common after PVI alone (77%) than additional SM (44%, P=0.002). After a follow-up time of 487 (429-570) days, only 20% of patients undergoing stand alone PVI remained in sinus rhythm when compared with 69% following PVI combined with SM (P=0.0001). Two patients assigned to PVI+SM experienced procedure-related complications (cardiac tamponade and minor stroke) which resolved without sequelae. CONCLUSION: PVI alone is insufficient in the treatment of persistent AF. However, additional left linear lesions increase the success rate significantly. Early AF-relapses are associated with a negative outcome after PVI alone but not following additional SM.     

Mapping und Katheterablation von Kammertachykardien bei Patienten mit isch?mischer Kardiomyopathie

The presence of ischemic cardiomyopathy is a common cause of ventricular tachycardia (VT) that often results in recurrent discharges from implanted defibrillators. The mechanism of most VTs in these patients is based on reentrant circuits caused by surviving myocytes within areas of dense scar tissue serving as a protected zone of slow conduction. These regions can be characterized in the electrophysiological laboratory by analyzing local electrograms and by conventional entrainment and pace-mapping. In the modern era of interventional electrophysiology, three-dimensional mapping systems are available facilitating the understanding of the substrate and supporting navigation within the ventricle. In 70–80% of patients, catheter ablation performed with irrigated electrodes is able to eliminate VT recurrence, which often requires shock. In about 10–15% of patients, an epicardial ablation attempt may be necessary to reach deeper or epicardially located reentrant circuits. Rare cases also may require transcoronary ethanol ablation restricted to centers with a high level of experience. Future developments, including enhanced catheter and mapping techniques and robot-navigated catheter steering, may be able to further increase the success rates of VT ablation in patients with ischemic cardiomyopathy.     

Classical homeopathy in the treatment of cancer patients - a prospective observational study of two independent cohorts

Background  

Many cancer patients seek homeopathy as a complementary therapy. It has rarely been studied systematically, whether homeopathic care is of benefit for cancer patients.     

Transvascular intracardiac ablation--on the current status of the method in the treatment of tachyarrhythmias

A survey is given on the method of the transvasal intracardiac ablation in the treatment of atrial and ventricular tachyarrhythmias. Experimental fundaments, indication, method and possible complications are reported. Own results on five patients with His bundle ablation are described. A possible further development of the method is the enlargement of the His bundle ablation to the ablation of focal arrhythmias, Kent's fibres and ventricular tachycardias without evocation of a total atrioventricular block. Alternative techniques of the cauterization, the laser ablation and the high frequency coagulation are described.     

Distribution of and physiologic factors that affect 131I-antiferritin tumor localization in experimental hepatoma

Polyclonal ¹³¹I rabbit anti-rat ferritin localizes in the H-4-II-E hepatoma model. The effect of tumor size, vascularity, and ferritin content on tumor localization was examined. The extravascular and intravascular quantity and location of ¹³¹I non-specific IgG and ¹³¹I-antiferritin IgG in tumors were determined by gamma counter analysis of tissue samples and autoradiography. Separate groups of 8–10 tumor bearing rats with 0.6–1 g, 1–3 g, 4–8 g, 8–14 g, and > 14 g tumors were injected with 500 μCi (200 μg) of ¹³¹I non-specific IgG or ¹³¹I-antiferritin. Tumor targeting with antiferritin occurred maximally in primary or metastatic lesions less than 1 g in size. Decreased localization occurred with increasing tumor size and no localization took place in tumors > 8 g in size. This finding is independent of administered dose because increasing the amount of injected antiferritin from 2- to 10-fold did not increase the antiferritin/normal IgG targeting ratio in any group of tumors > 4 g. The quantity and physical characteristics of the tumor vasculature may in part explain selective tumor localization. Tumor vascularity per gram as measured by ⁵¹Cr labeled erythrocytes decreased as tumor size increased. Decreased localization was evident in the necrotic portions of large tumors. Autoradiography of tumor sections revealed that most of the ¹²⁵I-IgG activity is deposited perivascularly with decreased deposition of antibody in necrotic areas of tumors and at increasing distance from the lumen of vessels. These findings have clinical importance since this non-homogeneous distribution of antibody could result in the delivery of low doses of radiation to large necrotic areas of tumors. These results help to demonstrate some of the complex physiologic factors that affect tumor localization and antibody distribution.     

Effect of mental stimulants on electroconvulsive shock-induced retrograde amnesia

The effect of nootropics on the retrograde amnesia induced by electroshock was studied on a model of the active conditioned escape reaction (pole jumping). In untreated animals the daily application of electroshock for three days, immediately after the training, led to a significant retardation of the development of a conditioned escape reaction. The administration of nootropics influences the development of the retrograde amnesia to different extents, the treatment regimen (application of the drug only during the training and supplementary pretreatment before the first day of training; respectively) being of importance. The antiamnestic effect of Piracetam (100 mg/kg, intraperitoneally) which is good also without pretreatment, may still be potentiated, especially on the fourth day of treatment, by an additional administration of the drug, beginning four days before the first day of treatment. In contrast to this, meclofenoxate hydrochloride (100 mg/kg, intraperitoneally) and pyritinol (100 mg/kg, intraperitoneally) produce a marked inhibition of the development of the retrograde amnesia only after pretreatment. Without pretreatment these drugs exert a slight or no effect. The marked antiamnestic effect of methylglucaminorotate (225 mg/kg, intraperitoneally) and by an additional pretreatment. As to dihydroergotoxin (1 mg/kg; intraperitoneally), both treatment regimens were ineffective in the model used.     

Selective tumor localization in experimental hepatoma by radiolabeled antiferritin antibody

The in vivo localization of 131I-radiolabeled antiferritin and normal IgG in the H-4-II-E rat hepatoma model was investigated by serial necropsy. Groups of 14 to 18 animals were injected with 500 microCi (200 micrograms) of normal and antiferritin IgG. The total dose from the nonpenetrating beta radiation was calculated for tumor and normal tissue, and expressed as a targeting ratio of antiferritin to normal IgG for each organ studied. The results demonstrate 2.9 times greater dose deposition in tumors of animals treated with 131I-antiferritin than with 131I-normal IgG. 131I-antiferritin deposited equivalently in primary tumors and metastatic lesions of similar size. The specific binding in tumors could be competitively inhibited by the addition of unlabeled antiferritin but not unlabeled normal IgG. Specific targeting with 131I-antiferritin comparison to 131I-normal IgG did not occur in any normal tissue. There was considerable variation in the dose deposition in different normal tissues.