Biomedical subjects
Publications and source records attributed to P Jaïs.
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Biventricular resynchronisation is an additional therapeutic option in the management of refractory heart failure, with a functional and haemodynamic benefit as well as an improved morbidity and mortality. However, the rate of non-responsive patients has prompted a re-think about the presumed mechanisms of action for this procedure. This study aims to identify candidates more successfully. Based on five years experience in this centre, our work confirmed a medium and long term clinical benefit with multisite pacing. Nevertheless, there was evidence of a relative discordance between the functional benefit and the haemodynamic impact in terms of ejection fraction achieved with resynchronisation. While QRS narrowing appears to be a predictive factor for a successful procedure, the ECG alone is not sufficient to select 'unsynchronised' candidates. Statistical analysis reveals that before implantation the independent predictive factors to identify non-responsive patients include the presence of a complication of myocardial infarction and a low grade mitral leak. The limits of the ECG suggest a more mechanical than electrical approach to understanding the mechanisms of action for resynchronisation. Its effectiveness in cases of right bundle branch block confirm the hypothesis of left intra-ventricular conduction defects, not apparent on the surface ECG but accessible through new imaging techniques. Based on the hypothesis of delayed movement of the ventricular walls, the principle of resynchronisation aims to restore homogenous contraction. Echocardiography allows observation of electromechanical delay and opens new perspectives in the future for selecting patients for pacing. Ar
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.
Sudden cardiac death frequently results from ventricular fibrillation (VF). While VF is frequently the eventual mode of death in patients with abnormal ventricular substrates, it has also been described in patients with structurally normally hearts. Until recently, the management of patients who have survived sudden cardiac death has focused on treating the consequences by implantation of a defibrillator. However, such therapy remains restricted in many countries, is associated with a prohibitive cost to the community, and may be a cause of significant morbidity in patients with frequent episodes or storms of arrhythmia. Evidence emerging from the study of fibrillation both in the atria and the ventricle suggests an important role for triggers arising from the Purkinje network or the right ventricular outflow tract in the initiation of VF. Initial experience in patients with idiopathic VF and even those with VF associated with abnormal repolarization syndromes (LQT or Brugada syndrome) or myocardial infarction suggests that long term suppression of recurrent VF may be feasible by the elimination of these triggers. With the development of new mapping and ablation technologies, and greater physician experience, catheter ablation of VF, with the ultimate aim of curing such patients at risks of sudden cardiac death, may not be an unrealistic goal in the future.
Atrial fibrillation, the most common arrhythmia, is frequently disabling and drug resistant and is associated with significant complications, especially thromboembolic events. Non-pharmacological approaches including surgery and catheter-based ablation have been developed for the most symptomatic patients. These new treatment strategies have dramatically increased our knowledge of the pathophysiology of this arrhythmia but most importantly have demonstrated that atrial fibrillation is curable. Since 1994, 2 different concepts have been used, aiming to modify the substrate responsible for AF maintenance using linear lesions, or to ablate the triggers located from within the pulmonary veins (PV) in about 90% of cases. The vast majority of the laboratories in the world are now using approaches centred on isolation of the PV. These approaches are far from being perfect but good enough to be offered in routine practice to selected patients in experienced centres. The importance of PVs in the initiation of AF has been clearly demonstrated and they also have a possible role in the maintenance of AF. However, the existence of non venous foci or a prominent substrate for AF maintenance limits the success rate to about 70%. As a consequence, a combination of PV isolation and linear lesions is commonly used. This more complex procedure carries a significantly higher success rate however with an increased risk of tamponade. As a consequence, we need to identify which patients will require linear lesions in addition to PV isolation. At the present time, AF ablation is restricted to symptomatic patients who have failed at least 1-2 antiarrhythmic drugs but future technical improvements based on presently applied concepts are likely to widen the indications for ablation therapy of AF.
UNLABELLED: Catheter ablation techniques for atrial fibrillation have undergone an extensive evolution, starting with linear lesions in the right, then the left atria before being superseded by ablation of triggers, mainly from the pulmonary veins. We investigate the feasibility and results of combined pulmonary vein and linear ablation utilizing a specific linear lesion connecting the lateral mitral annulus to the left inferior pulmonary vein (left isthmus). METHODS: 115 patients (101 M: 54 +/- 9 years) with paroxysmal atrial fibrillation (7 +/- 5 years) resistant to 4 +/- 1.6 anti-arrhythmic drugs were studied. After electrophysiologically guided disconnection of all four pulmonary veins, the left isthmus line was performed with an irrigated tip catheter. Complete linear block was demonstrated during coronary sinus pacing by local mapping looking for widely separated double potentials and confirmed by differential pacing. Mapping and ablation from within the coronary sinus was performed if an epicardial gap was detected after unsuccessful endocardial radiofrequency delivery. RESULTS: 100% of pulmonary veins were successfully disconnected and the left isthmus line was complete with bi-directional block in 88% after a mean of 22 +/- 12 min of endocardial radiofrequency delivery in 44 patients. In 58 patients, additional radiofrequency delivery was required from within the coronary sinus for 5 +/- 5 min. After a follow-up of 6.5 +/- 2.6 months and a mean of 1.4 +/- 0.6 procedures/patient, 79% were in stable sinus rhythm without antiarrhythmic drugs. CONCLUSION: the left isthmus line is feasible and safe and when performed in addition to pulmonary veins isolation can contribute to an increased success rate.
The possibility of curing patients suffering from paroxysmal atrial fibrillation using a radiofrequency ablation treatment is a major change in the management of this arrhythmia. Pulmonary vein disconnection is efficient and safe after a learning curve of the operator. This pulmonary vein isolation is the first and mandatory step allowing disappearance of atrial fibrillation in 70% of the patients. Modification in fibrillatory substrate using linear lesions increases the rate success to 75% in chronic atrial fibrillation and to 82% in paroxysmal atrial fibrillation. The radiofrequency ablation of atrial fibrillation should be considered as a surgical treatment without an open heart, isolating structures and cutting tissues are technical improvements (new radiofrequency catheters) will probably facilitate in the future. Some comparative studies with medical treatment are currently evaluating their efficacy, safety and respective cost and they may lead to a considerable increase in the number of patients who could benefit from these curative treatments.
OBJECTIVE: To correlate, in patients with right ventricular pacing (RVP), the QRS width with electromechanical variables assessed by pulsed Doppler tissue imaging echocardiography. Secondly, to find reliable parameters for selecting RVP patients who would respond to biventricular pacing (BVP). METHODS: 26 randomly selected control patients with RVP (mean (SD) ejection fraction 74 (3)%) (group A) were matched on sex and age criteria with 16 RVP patients with drug resistant heart failure (mean (SD) ejection fraction 27 (5)%) (group B). All patients were pacemaker dependent and all underwent pulsed Doppler tissue imaging echocardiography. This technique provided the intra-left ventricular (LV) electromechanical delay and the interventricular electromechanical delay. The Gaussian curve properties of data from group A patients provided the normal range of ECG and echographic parameters. DESIGN: Prospective study. SETTING: University hospital (tertiary referral centre). RESULTS: Data from the control group showed that an interventricular electromechanical delay or an intra-LV electromechanical delay > 50 ms would identify patients with a significantly abnormal ventricular mechanical asynchrony (p < 0.05). In the same manner, a QRS width > 190 ms was considered significantly larger in group B patients (p < 0.05) than in controls. In Group B patients, there was no correlation between the QRS width and the interventricular electromechanical delay (r = -0.23, NS) or the intra-LV electromechanical delay (r = 0.19, NS). Seven group B patients (44%) were misclassified by ECG criteria for ventricular mechanical asynchrony identification: four patients (25%) had a QRS width similar to that of controls but with a significantly prolonged intra-LV electromechanical delay and interventricular electromechanical delay; and three patients (19%) had a QRS width significantly larger than that in controls but without significant ventricular mechanical asynchrony. CONCLUSIONS: The QRS width is not a reliable tool to identify RVP patients with ventricular mechanical asynchrony. In RVP patients, an interventricular electromechanical delay or intra-LV electromechanical delay > 50 ms reflects a significant ventricular mechanical asynchrony and should be required to select patients for upgrading to BVP.
For physicians who are not familiar with the electrical basis of cardiac stimulation, high impedance leads previously (10 years ago) considered as bad electrodes (high voltage) are now considered as the 'epitome' of lead technology (low energy drain): clearly impedance is not a good parameter for characterizing the qualities of a pacing lead. Using a simplified approach to the electrostimulation 'paradigm', it is easy to establish that modern high impedance leads are in fact high current density leads and high efficiency leads (better description). It is also possible to establish that routine programming of the safety margin at 100% above threshold parameters is associated with a decrease in the penetration of the electric field according to the reduction of the cathode surface area. For safety and energy saving, a small tip electrode could be combined with a low polarization surface treatment and a reduction in fibrosis development between electrode and myocardium.
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OBJECTIVE: To compare clinical and haemodynamic variables between left ventricular and biventricular pacing in patients with severe heart failure; and to analyse haemodynamic changes during daily life and maximum exercise during chronic left ventricular and biventricular pacing. DESIGN: Prospective single blinded randomised study with crossover. SETTING: University hospital (tertiary referral centre). PATIENTS AND METHODS: 13 patients (mean (SD) age, 62 (6) years) with chronic atrial fibrillation, severe heart failure (mean ejection fraction 24 (8)%), and QRS prolongation of > or = 140 ms had His bundle ablation and installation of a pacemaker providing left ventricular and biventricular pacing. The pacemaker was equipped with a peak endocardial acceleration (PEA) sensor. The PEA pattern was used as a haemodynamic marker during exercise as it is highly correlated with left ventricular dP/dt. After a baseline period of right ventricular pacing, all patients had two months of left ventricular pacing and two months of biventricular pacing in random order. At the end of each phase, an echocardiogram, a haemodynamic analysis at rest and on exercise during a six minute walk test, and a cardiopulmonary exercise test were performed. RESULTS: PEA values were higher with left ventricular pacing (0.58 (0.38) m/s) and biventricular pacing (0.62 (0.24) m/s) than at baseline (0.49 (0.18) m/s) (p < 0.05). The six minute walk test showed similar performance in both pacing modes, but patients had more symptoms with left ventricular pacing at the end of the test (p = 0.035). On cardiopulmonary exercise testing, there was a greater increase in mean percentage variation of PEA with biventricular pacing than with left ventricular pacing (125 (18)% v 97 (36)%, respectively; p = 0.048) and better performance figures (92 (34) W v 77 (23) W; p = 0.03). CONCLUSIONS: During symptom limited and daily life exercise tests, chronic biventricular pacing provides better haemodynamic performance than left ventricular pacing. In heart failure patients with wide QRS complexes, the interventricular dyssynchronisation induced by left ventricular pacing may impair myocardial function during exercise.
Atrial fibrillation is the most frequently encountered arrhythmia in the human species. Its danger is widely appreciated but it remains for certain patients and their practitioners an awkward or even exasperating problem. Only surgery and radiofrequency ablation allow certain patients to be cured. The surgical approach is of course warranted in the case of an otherwise necessary cardiac intervention. In the absence of a surgical indication, endovenous ablation, which is less aggressive, is preferred. The procedure consists of disconnecting the pulmonary veins which "house" 80 to 95% of the foci, together with the ablation of further non-venous foci, which are always difficult to treat. Side effects in experimental centres are rare and 70% of patients are cured, which allows cessation of antiarrhythmic and anticoagulant treatments. The procedure is currently offered to symptomatic patients having had at least one episode every ten days in spite of antiarrhythmics.
OBJECTIVES: We sought to assess the value of 12-lead electrocardiogram (ECG) P-wave morphology to recognize the paced pulmonary vein (PV). BACKGROUND: Prediction of arrhythmogenic PVs producing ectopy or initiating atrial fibrillation (AF) using 12-lead ECG may facilitate curative ablation. METHODS: In 30 patients P-wave configurations were studied during sinus rhythm and during pacing at six sites from the four PVs: top and bottom of each superior PV and both inferior PVs. The P-wave amplitude, duration and morphology were assessed, and predictive accuracies were calculated for the most significant parameters. An algorithm predicting the paced PV was developed and prospectively evaluated in a different population of 20 patients. RESULTS; Three criteria were used to distinguish right from left PV: 1) a positive P-wave in lead aVL and the amplitude of P-wave in lead I > or =50 microV indicated right PV origin (specificity 100% and 97%, respectively); 2) a notched P-wave in lead II was a predictor of left PV origin (specificity 95%); and 3) the amplitude ratio of lead III/II and the duration of positivity in lead V(1) were also helpful in distinguishing left versus right PV origin. In addition, superior PVs could be distinguished from inferior according to the amplitude in lead II (> or =100 microV). In prospective evaluation, an algorithm based on the above four criteria identified 93% of left versus right PV and totally 79% of the specific PVs paced. CONCLUSIONS: Pacing from the different PVs produced a P-wave with distinctive characteristics that could be used as criteria in an algorithm to identify the PV of origin with an accuracy of 79%.
In patients with a wide QRS, drug-resistant heart failure, and a coronary sinus that is unsuitable for transvenous biventricular pacing (BVP), a transseptal approach from the right to left atrium can allow endocardial left ventricular (LV) pacing (with permanent anticoagulant therapy) instead of epicardial pacing via the coronary sinus branches. We sought to compare the effects of endocardial pacing with those of epicardial LV pacing on regional LV electromechanical delay (EMD) and contractility. Twenty-three patients (68 +/- 8 years) with severe heart failure and QRS > or =130 ms received a pacemaker for BVP. Fifteen patients underwent epicardial LV pacing, and 8 underwent endocardial LV pacing because of an unsuitable coronary sinus. All LV leads were placed at the anterolateral LV wall. Six months after implant, echocardiography and Doppler tissue imaging were performed. LV wall velocities and regional EMDs (time interval between the onset of the QRS and local ventricular systolic motion) were calculated for the 4 LV walls and compared for each patient between right ventricular (RV) and BVP. The amplitude of regional LV contractility was also assessed. Epicardial BVP reduced the septal wall EMD by 11% versus RV pacing (p = 0.05) and the lateral wall EMD by 41% versus RV pacing (p <0.01). With endocardial BVP, the septal and lateral EMDs were 21.3% and 54%, respectively (p <0.01, compared with epicardial BVP). The mitral time-velocity integral increased by 40% with endocardial BVP versus 2% with epicardial BVP (p <0.01). The amplitude of the lateral LV wall systolic motion increased by 14% with epicardial BVP versus 31% with endocardial BVP (p = 0.01). This resulted in a LV shortening fraction increase of 25% in patients with endocardial BVP (p = 0.05). However, all patients were clinically improved at the end of follow-up. Thus, in heart failure patients with BVP, endocardial BVP provides more homogenous intraventricular resynchronization than epicardial BVP and is associated with better LV filling and systolic performance.
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The implantation of permanent pacemakers in patients with congenital heart disease can be challenging. This report describes the complexity of pacemaker implantation in a patient with Ebstein's disease, tricuspid valve replacement, and right atrial abnormalities like severe intra- and interatrial conduction block that prevented dual chamber pacing from conventional sites. This case illustrates the promising possibility to circumvent the interatrial conduction block with single left atrial pacing instead of biatrial pacing which was not suitable here.
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