[Right accessory pathways with slow and decremential anterograde conduction. Electrophysiological changes during ablation of the proximal atrial poles]. / Les voies accessoires droites à conduction antérograde lente et décrémentielle. Observations électrophysiologiques lors de leur ablation centrée sur l'insertion proximale atriale.

Right sided accessory pathways with slow and decremential anterograde conduction differ from the anatomical substrates of the nodo-ventricular connections described by Mahaim. The connection may also be atrio-ventricular or atrio-fascicular. The authors report a series of 6 patients (2 men, average age 31 +/- 9 years) with antidromic reciprocating tachycardia implicating accessory pathways with decremential conduction (wide QRS complexes with left bundle branch block) the radiofrequency ablation of which was centered on the proximal atrial pole. The increment of pre-excitation was 75 +/- 18 ms. No nodo-ventricular or nodo-fascicular connections were observed. One patient had an atrio-ventricular connection, the mapping and ablation (5 applications) of which were performed on the annulus, as if it were a bundle of Kent. Five patients had a nodo-fascicular connection which was masked during sinus rhythm. The localisation of the proximal atrial insertion on the tricuspid annulus was initially estimated by studying the superior junction of the circuit and by endocavitary stimulation, and then by recording the M potential (activation of the accessory pathway). This was recorded in 4 patients, either at a specific point on the annulus (lateral or postero-lateral) which was the target of ablation (3 patients, 5 +/- 3 applications) or over a wider region (2 cm) at which ablation failed (1 patient: 13 applications). The site of the increment was determined in 2 patients and was proximal to the M potential. The M potential could not be recorded on the annulus in one patient. In 2 patients, the M potential was also recorded along the side of the pathway on the antero-lateral wall of the right ventricle of the tricuspid valve at its distal pole. In 2 patients, ablation was centered on the distal pole in second intention, near to the terminal part of the right bundle where it was localised in one of the two (18 applications). Finally, ablation was obtained in 5 out of 6 patients. They remain asymptomatic after 12 +/- 7 months follow-up. These cases show that accessory pathways with slow decremential conduction usually behave like a complete conduction pathway with an accessory laterally situated atrioventricular node on the tricuspid, an accessory bundle and a distal insertion which are all accessible to ablation.

[Role of photon absorption densitometry of the bone in uremic osteodystrophy]. / Ruolo della densitometria ossea ad assorbimento fotonico nella osteodistrofia uremica.

The aim of this investigation is to evaluate the role of bone photonic densitometry in uremic osteodystrophy. Bone mineral content (BMC) and bone density (BD) have been measured in 80 hemodialyzed patients by double photonic emission densitometry. Photonic densitometry shows an higher sensibility to quantitative changes in bone mineral content than metacarpal index (IM). Photonic densitometry is unable to differentiate osteoporosis from osteomalacia; this differential diagnosis can be obtained by radiological analysis: low BD and low IM means osteoporosis, low BD and resorptive changes in cortical bone means osteomalacia and/or hyperparathyroidism. Photonic densitometry is particularly suitable for uremic osteodystrophy follow-up because of its easy repetitiveness and innocuousness and for its close correlation with iPTH variations.

[Anti-arrhythmic efficacy of the amiodarone-mexiletine combination in the treatment of resistant complex ventricular arrhythmias]. / Efficacia antiaritmica dell'associazione amiodarone-mexiletina nel trattamento di aritmie ventricolari complesse resistenti.

The efficacy and safety of combined amiodarone and mexiletine treatment was investigated in 16 patients with chronic complex ventricular arrhythmias previously refractory to conventional antiarrhythmic agents and, in a lesser degree, to mexiletine or amiodarone. Many patients had a poor left ventricular function. Oral amiodarone was started using a loading dose of 600 mg daily for one week, 400 mg daily for one week, and a subsequent dosage of 200 mg daily five times a week. After twenty-one days of this treatment mexiletine was administered in combination (600 mg/day orally), if a 24-hour ambulatory ECG had revealed a partial suppression of the ventricular arrhythmias (14 out of 16 patients). On the fourth day of combined amiodarone and mexiletine treatment, analysis of a 24-hour ambulatory ECG showed a marked diminution of the ventricular ectopic activity compared with the pretreatment period. The average percentages of reduction for PVCs and couplets were 88% and 97%. Total suppression of TV runs/24 hr was achieved in all patients. Ventricular arrhythmias relapse was found in all patients during early mexiletine washout (phase 4) and in 12 patients during late mexiletine washout (phase 5). Amiodarone and mexiletine combination did not appear to reduce left ventricular function. Minor side effects occurred in some patients. Follow-up from 3 months to two years (mean 16 months) showed that maintenance treatment had achieved remarkable antiarrhythmic effects (Holter control). However, sudden cardiac death occurred in two patients with very depressed left ventricular function. We conclude that a combined amiodarone and mexiletine treatment effectively reduces the frequency and grade of PVCs and does not impair left ventricular performance. However, it does not prevent sudden cardiac death in patients with poor left ventricular function.

[Comparison of the anti-arrhythmic effects of propafenone and aprindine in the treatment of refractory chronic ventricular arrhythmias. A randomized double-blind crossover study controlled with placebo]. / Confronto tra l'efficacia antiaritmica del propafenone e dell'aprindina nel trattamento di aritmie ventricolari croniche resistenti. Studio randomizzato crossover, a doppio cieco, controllato con placebo.

A placebo-controlled, randomized, double-blind, crossover study was performed in 14 patients with chronic, resistant, ventricular arrhythmias in order to evaluate the efficacy and safety of two new antiarrhythmic agents, propafenone and aprindine. After an initial placebo phase, patients received orally either propafenone (600 mg daily) or aprindine (150 mg daily for the first two days and 50 mg every 12 hours successively) for five days. This treatment was followed by a drug-free period (placebo II); patients were then crossed over to the alternative drug. A 24-hour Holter recording was performed during the last 48 hours of the initial placebo phase and on the final day of each phase of the crossover period. Analysis of Holter recordings revealed that the mean hourly PVCs frequency, for the group, was similar during the two control periods. Significant reduction in the mean hourly frequency of PVCs from control levels was observed in 78% of the patients during propafenone therapy and in 42% during aprindine therapy. For the whole group, propafenone induced a significant reduction of the average PVCs/h frequency (p less than 0.05), whereas the aprindine was ineffective. Finally no patient experienced side effects with propafenone, whereas aprindine caused side effects in three patients (dizziness, tremor, ataxy).

[Preliminary clinical and experimental data on a new anti-arrhythmic drug: lorcainide]. / Primi rilievi clinici e sperimentali su un nuovo antiaritmico: la lorcainide.

A first series of personal results in the treatment of arrhythmia with lorcainide is presented. Findings were obtained by recording for 24 hr with Holter and compared with those observed in patients treated with quinidine. An ECG study was also made of the atrial and nodal refractory periods. The conclusion is drawn that lorcainaide possesses an undoubted and protracted anti-arrhythmic effect, and does not exert a significant influence on refractory period values.