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Much of our understanding of the mechanisms of macro re-entrant atrial tachycardia comes from study of cavotricuspid isthmus (CTI) dependent atrial flutter. In the majority of cases, the diagnosis can be made from simple analysis of the surface ECG. Endocardial mapping during tachycardia allows confirmation of the macro re-entrant circuit within the right atrium while, at the same time, permitting curative catheter ablation targeting the critical isthmus of tissue located between the tricuspid annulus and the inferior vena cava. The procedure is short, safe and by demonstration of an electrophysiological endpoint - bidirectional conduction block across the CTI - is associated with an excellent outcome following ablation. It is now fair to say that catheter ablation should be considered as a first line therapy for patients with documented CTI-dependent atrial flutter.

The aim of this study was to assess the long-term performance of a new dual chamber rate responsive pacing system based on the dynamic measurement of the peak endocardial acceleration (PEA) index of cardiac contractility. Seventy patients who participated in the Multicenter European Clinical Evaluation were studied 1 year after implantation by continuously recording the PEA and the heart rate (HR) during exercise stress testing and during 24 hours of usual activities. A complete examination of standard parameters was also performed to assess the pacing/sensing lead characteristics. Statistical comparisons were performed with the data recorded with the same protocol at 1 month after implant for each patient. A linear correlation coefficient was calculated between PEA and sinus rate when the patient showed predominant atrial tracked rhythm. There were no significant differences between PEA values measured at 1 month and 1 year (PEA = 0.41 +/- 0.26 g vs 0.45 +/- 0.29 g at rest and PEA = 1.63 +/- 0.77 g vs 1.72 +/- 0.83 g during peak exercise). The correlation coefficient remained stable (0.67 +/- 0.15 vs 0.65 +/- 0.14 during daily life and 0.74 +/- 0.14 vs 0.77 +/- 0.11 during exercise). The PEA signal detected by the sensor was reliable and stable. No long-term complications or adverse effects were observed, and the lead performance was comparable to that of a standard lead.

Ablation of the atrioventricular junction consists in creating a therapeutic AV block to facilitate the treatment of symptoms caused by atrial arrhythmias refractory to drug therapy. The technical performance of ablation has been improved by restricting the indication to atrial fibrillation, by using radiofrequency currents, by choosing a nodal rather than His bundle ablation site, and by improving the function of cardiac pacemakers (rate adapting, back-up). The functional results are excellent but the outcome is punctuated by rare cases of sudden death, the cause of which is not fully understood (dependance, ventricular arrhythmias, ...). To avoid permanent pacing, it has been suggested that atrioventricular conduction should be modulated rather than completely interrupted. Modulation of the fast pathway has been shown to be ineffective; that of the more complex, slow pathway, seems to be more promising. Although this obviates the need for a pacemaker, it does not suppress irregularity of the ventricular rhythm, the main cause of symptoms in paroxysmal atrial fibrillation and of the haemodynamic changes associated with permanent atrial fibrillation.

Left ventricular hypertrophy is an important risk factor in hypertension and the results of the HYCAR study confirm that it is possible to treat this risk factor independently of an action on the blood pressure. Should systematic echocardiography be performed in every hypertensive patient to diagnose left ventricular hypertrophy and follow up its outcome with treatment? This attitude seems to be premature for two reasons. Firstly, echocardiography, though much more sensitive than electrocardiography for diagnosing left ventricular hypertrophy, has a number of limitations. Good recordings cannot be obtained in all patients; even under the best conditions of reproducibility, the measurement of left ventricular mass is not excellent and does not allow reliable individual follow-up of treatment; even the criteria of left ventricular hypertrophy used at present are open to criticism. Secondly, it remains to be shown whether the reversibility of left ventricular hypertrophy, independently of lowering the blood pressure, improves the prognosis of the hypertensive patient. The intensive research into this problem, further stimulated by the encouraging results of the HYCAR study, should help define the role and value of echocardiography in the future management of hypertension.

Conversion to sinus rhythm (cardioversion) is recommended to prevent the haemodynamic and thromboembolic complications of atrial fibrillation. Prior anticoagulation is compulsory except in emergencies. The duration of anticoagulant therapy depends on the terrain and chronicity of the arrhythmia. Cardioversion may be proposed for the majority of patients in whom it is thought that sinus rhythm can be maintained by appropriate therapy. It may be carried out pharmacologically by oral or intravenous antiarrhythmic therapy. Amiodarone is the drug of choice. Cardioversion may also be carried out by external or internal direct current shock. The success rate of external electrical defibrillation depends on the energy administered, the site of the electrodes and a number of factors related to thoracic impedence. Internal electrical defibrillation may be performed with an endocavitary catheter or by the oesophageal approach, with few complications. The main problem resides in maintaining sinus rhythm in the long term. When this is not possible, cardioversion is useless, and therapy to slow the cardiac rhythm should be instituted.

Ambulatory monitoring of Korotkoff sounds appearance time (QKD interval) was performed during 24 hours in 131 normal subjects (85 males, 46 females, aged 14-78 years, mean 36 +/- 15 years) with a new device (Diasys 200RK, Novacor-France). This device allows simultaneous measurements of blood pressure, heart rate and QKD interval at programmed intervals, every 15 minutes in this study. For each patient we calculated the average 24th QKD interval, the QKD interval for a systolic BP of 100 mmHg and a heart rate of 60 bt/min (QKD: 100-60), and the slope (S) of the variations of the QKD interval against systolic BP and pulse pressure (PP). Results are presented for each 10 years age group (mean +/- SD).

To optimise the regulation of rate responsive pacemakers, the authors propose standardized tests of everyday activities. Seven tests were selected with monitoring of the heart rate (HR) by telemetry every 30 seconds: two reference tests--cycloergometry: 2 steps of 3 minutes at 30 then 60 watts and a symptoms-limited Bruce protocol on the treadmill--and 5 everyday activities, walking, going upstairs, going downstairs, squats and hyperventilation. Fifteen normal subjects (65 +/- 10 years) were used to establish normal values and 10 patients implanted with a Telelctronics Meta DDDR 1250 rate responsive pacemaker with minute ventilation sensing, were studied after choice of minimal and maximal HR on clinical criteria (age, pathology). The rate response frequency (RRF) was adjusted so that the pacemaker HR was within normal values. At the beginning of each test, the sensor was hypokinetic (p = 0.01). Hyperventilation caused hyperkinesia of the sensor (p = 0.01). A good correlation was obtained between PM patients and normal subjects on walking, going up down stairs and for squats (p = NS). On cycle ergometry and treadmill, the PM remained slightly hypokinetic (p = 0.02). The study of "ideal" RRF measured at "peak exercise" as proposed by the manufacturer was only satisfactory in 1 of the 10 cases. This study confirms the value of using everyday activities for programming rate responsive pacemakers, the limitations of automatic adjustment and the need for personalized programming.