Biomedical subjects

D Lacroix

Publications and source records attributed to D Lacroix.

At least 37 records · Page 2Linked to original sources

PubMed2000

Chronic amiodarone effects on epicardial conduction and repolarization in the isolated porcine heart.

Amiodarone is a potent antiarrhythmic agent with complex chronic effects, notably on repolarization and conduction, that are not fully understood. Its low arrhythmogenic potential has been related to a lack of increase in repolarization dispersion. Since its effects are not documented in pigs we conducted a mapping study of activation and repolarization in isolated perfused porcine hearts. Amio20 female pigs (n = 7) received amiodarone 20 mg/kg per day over 4 weeks while Amio50 female pigs (n = 7) received 50 mg/kg per day over 4 weeks. Concentrations of the drug encompassed values found in clinical studies. Then, activation patterns and activation-to-recovery intervals (ARI) were mapped epicardially from 128 unipolar electrograms in isolated perfused hearts in corroboration of epicardial action potential recordings. Mean ARI was longer in Amio20 experiments compared to the seven control hearts (325 +/- 11 ms vs 288 +/- 5 ms at 1,000 ms), whereas ARI dispersion was not different, being comprised between 7 and 11 ms and generating smooth gradients. In Amio50 experiments, mean ARI was further prolonged (390 +/- 10 ms at 1,500 ms) with an exaggerated reverse rate dependence concomitant with a depressant effect on the plateau of the action potential. Again, ARI dispersion did not differ from controls. Finally, the drug depressed the maximal rate of depolarization (Vmax) and slowed conduction in a rate dependent and concentration dependent fashion. In conclusion, chronic amiodarone induces Class I and Class III antiarrhythmic effects in ventricular porcine epicardium that are concentration dependent but does not affect dispersion of repolarization. This may partly explain its low arrhythmogenic potential.

Action Potentials↗

PubMed2000

Three-dimensional finite element analysis of glenoid replacement prostheses: a comparison of keeled and pegged anchorage systems.

Glenoid component loosening is the dominant cause of failure in total shoulder arthroplasty. It is presumed that loosening in the glenoid is caused by high stresses in the cement layer. Several anchorage systems have been designed with the aim of reducing the loosening rate, the two major categories being "keeled" fixation and "pegged" fixation. However, no three-dimensional finite element analysis has been performed to quantify the stresses in the cement or to compare the different glenoid prosthesis anchorage systems. The objective of this study was to determine the stresses in the cement layer and surrounding bone for glenoid replacement components. A three-dimensional model of the scapula was generated using CT data for geometry and material property definition. Keeled and pegged designs were inserted into the glenoid, surrounded by a 1-mm layer of bone cement. A 90 deg arm abduction load with a full muscle and joint load was applied, following van der Helm (1994). Deformations of the prosthesis, stresses in the cement, and stresses in the bone were calculated. Stresses were also calculated for a simulated case of rheumatoid arthritis (RA) in which bone properties were modified to reflect that condition. A maximum principal stress-based failure model was used to predict what quantity of the cement is at risk of failure at the levels of stress computed. The prediction is that 94 percent (pegged prosthesis) and 68 percent (keeled prosthesis) of the cement has a greater than 95 percent probability of survival in normal bone. In RA bone, however, the situation is reversed where 86 percent (pegged prosthesis) and 99 percent (keeled prosthesis) of the cement has a greater than 95 percent probability of survival. Bone stresses are shown to be not much affected by the prosthesis design, except at the tip of the central peg or keel. It is concluded that a "pegged" anchorage system is superior for normal bone, whereas a "keeled" anchorage system is superior for RA bone.

Bone Cements↗

PubMed2000

[Determinants of survival after implantation of an automatic defibrillator. Report of 127 patients].

The authors present a retrospective and longitudinal study of the predictive factors of mortality in patients having an implanted automatic defibrillator. The population comprised 127 patients implanted between September 1988 and September 1997. There were 107 men with a mean age of 57.7 +/- 13 years. The left ventricular ejection fraction was 39.3%. The proportion of coronary patients was 68%; 20% of patients had atrial fibrillation and 5% were in Class III of the NYHA classification. The indications were: resuscitated cardiac arrest (N = 56) and poorly tolerated ventricular tachycardia (N = 71). The follow-up period was 30 +/- 25 months. There were 23 early and 10 late complications. Seventy-two patients had received an electric shock; 57 had an appropriate shock. There were 23 arrhythmic storms (ventricular arrhythmia requiring at least 2 shocks in less than 24 hours) in 17 patients. The operative mortality was 1.1%; at 1 year, the global survival was 93.9 +/- 2.2%; cardiac survival was 94.7 +/- 2.1%; survival without sudden death was 98.3 +/- 1.2%. Multivariate analysis isolated predictive factors for mortality; atrial fibrillation was predictive for global mortality; an ejection fraction < 30% and the fact of having received an appropriate shock were predictive of cardiac mortality; and an arrhythmic storm was predictive of sudden death.

Adult↗

PubMed1999

Ventricular tachycardia originating from the posteroseptal process of the left ventricle with inferior wall healed myocardial infarction.

Ventricular tachycardia (VT) substrates may form in preferential locations and similar electrocardiographic patterns may be observed when ventricular activation starts from a particular site. We examined the role of the posterior inferior process of the left ventricle in the mechanism of VT occurring after inferior wall myocardial infarction. We reviewed isochronal maps of 40 VTs obtained at surgery in 13 patients, with a 128-electrode system using epicardial sock and endocardial balloon electrode arrays. Based on the epicardial to left endocardial relation we observed 7 tachycardias in 7 patients with onset of activation over the crux of the heart. This activation mimicked excitation through a posteroseptal accessory pathway. Endocardial activation maps showed breakthroughs occurring 6 to 40 ms later and did not give evidence in favor of macroreentry. In all but 1 VT, left-axis deviation was present (-30 to -75 degrees) with a positive concordance from leads V2 to V6 (QRS wave patterns were variable in V1). These tachycardias, which were clinical in 3 of 7 cases, were interpreted as arising from the posterior inferior process of the left ventricle and successfully ablated by left septal and epicardial cryolesions. In another patient, this concept was further validated by percutaneous radiofrequency ablation of a tachycardia with the previously described morphology. In conclusion, VT may originate from the posteroseptal process of the left ventricle with inferior wall healed myocardial infarction. Because these tachycardias can be successfully eliminated, their characteristic morphologies may provide clinical markers for the identification of patient candidates to surgical or nonsurgical ablative therapy.

Adult↗

PubMed1999

Extraction of endocardial implantable cardioverter-defibrillator leads.

Despite a growing number of implantable cardioverter-defibrillator (ICD) lead removal indications, there is no consensus about extraction techniques. We applied our experience of pacemaker lead removal to ICD leads using a superior approach with a standard extractor kit, and an inferior approach with a lasso, or a surgical extraction. Fifteen leads were removed in 11 patients during 12 procedures (1 patient was referred twice): 11 right ventricular defibrillation leads, 3 right atrial coils, and 1 atrial lead implanted with a DDD-ICD. The indication for lead extraction was insulation failure (n = 4), conductor fracture (n = 2), abdominal pocket infection (n = 4), lead endocarditis (n = 1), and replacement of an atrial coil by an atrial lead for DDD-R pacing (n = 1). One patient had surgical extraction of 2 leads because of an endocarditis with large vegetations on a DDD-ICD. In 11 other cases, 5 leads were removed using a superior approach with a standard extraction kit and 8 leads were removed by a femoral approach using a lasso alone or added to a pigtail catheter. There was no failure of explantation. One extraction attempt failed with the superior approach but was successful with a secondary inferior approach. The main difficulties encountered were due to tight adherence of the proximal coil to the venous wall and to dislodgment of passive fixation leads from their endocardial insertion. One patient had subclavian vein thrombosis after intervention; no major complication was noted. Ten patients immediately underwent reimplantation. Two patients (1 with an endocarditis and 1 free of ICD therapy for 5 years) did not have reimplantation. During a 4- to 44-month follow-up, no late complication appeared. Thus, ICD lead explantation can be performed with a good success rate, with extraction techniques similar to those used for pacemaker leads.

Aged↗

PubMed1999

Factors affecting epicardial dispersion of repolarization: a mapping study in the isolated porcine heart.

OBJECTIVE: Non-uniform drug-induced prolongation of repolarization predominating in the midmyocardial (M) cell layers has been shown to be responsible for perpetuation of reentry, giving rise to torsade de pointes. However, the absence of M cells in immature animals, especially the pig, suggests other possible underlying mechanisms. We sought to examine, in this species, the effects of predisposing factors to torsade de pointes on the dispersion of epicardial repolarization and their contribution to arrhythmogenesis. METHODS: Computerized mapping of repolarization and activation was conducted on the epicardial surface in 29 Langendorff-perfused hearts of eight-week-old pigs. Activation-recovery intervals were measured simultaneously from 128 unipolar electrograms. RESULTS: Baseline iso-interval maps were dipolar (41%) or multipolar (59%). Dispersion of repolarization was reverse frequency-dependent but was unaffected by lowering [K+]o. DL-Sotalol (0.1 mmol/l) reinforced local gradients and thus increased epicardial dispersion, whereas intramural recordings did not demonstrate any predominant effect in midmyocardial layers. Phenylephrine (1 mumol/l) notably augmented DL-sotalol effects. After [Mg++]o lowering, although dispersion was not significantly increased, DL-sotalol was associated with the spontaneous occurrence of polymorphic ventricular tachycardia in seven out of nine experiments. When maps of repolarization of escape beats were compared with activation maps of first arrhythmic beats, an arc of functional dissociation was observed in the vicinity of a steep gradient of repolarization in two out of nine tachycardias. CONCLUSION: Epicardial dispersion of repolarization is increased by slow rates, DL-sotalol and phenylephrine but is not the only requirement for initiation of polymorphic ventricular tachycardia. In combination with other factors, it helps continuation of the arrhythmia in this model.

Adrenergic alpha-Agonists↗

PubMed1999

Seminal vesicle production and secretion of growth hormone into seminal fluid.

Production of foreign proteins in the tissues of transgenic animals represents an efficient and economical method of producing therapeutic and pharmaceutical proteins. In this study, we demonstrate that the mouse P12 gene promoter specific to the male accessory sex gland can be used to generate transgenic mice that express human growth hormone (hGH) in their seminal vesicle epithelium. The hGH is secreted into the ejaculated seminal fluids with the seminal vesicle lumen contents containing concentrations of up to 0.5 mg/ml. As semen is a body fluid that can be collected easily on a continuous basis, the production of transgenic animals expressing pharmaceutical proteins into their seminal fluid could prove to be a viable alternative to use of the mammary gland as a bioreactor.

Animals↗

PubMed1999

Single center experience with femoral extraction of permanent endocardial pacing leads.

Between March 1995 and June 1997, 128 leads were extracted from the hearts of 28 women and 50 men, 69 +/- 15 years of age (mean +/- SD, range 22-92 years). The indications for the procedure were: Accufix leads in 18 patients (14%), dysfunction or incompatibility with ICD in 16 (12%), endocarditis on the lead in 41 (32%), pulse generator pocket infection in 28 (22%), and pulse generator and/or lead erosion in 25 patients (19%). The extraction was performed with a snare (lasso), via a femoral vein as a first approach in 116 leads, and as an alternate approach, after extraction from the original site of implantation had failed, in 12 leads. The leads had been implanted for 62 +/- 48 months (range 1-205 months). A Cook sheath was used in 7, and a femoral approach traction in 20 instances. Of the 128 leads, 122 (95%) were completely extracted, and 2 (2%) were partially extracted (the distal electrode remaining attached to the myocardium), and 4 (3%) could not be removed. Four complications occurred: 2 tears of the tricuspid valve without clinical consequences, one separation of the lead's distal electrode which migrated into the hypogastric vein, and one hemorrhage at the femoral puncture site. There was no death or serious complication caused by lead extraction in this series.

Adult↗

PubMed1999

Extraction and reimplantation of defibrillation leads through a thrombotic subclavian vein.

Venous thrombosis is one of the most frequently encountered obstacles when reintervening on endocardial leads. We report on two patients with a ventricular defibrillator requiring lead replacement in whom a subclavian vein thrombosis was documented prior to the intervention. We recanalized the vein and replaced the lead through the same path to preserve the venous access.

Defibrillators, Implantable↗

PubMed1999

Intraoperative computerized mapping of ventricular tachycardia: differences between anterior and inferior myocardial infarctions.

INTRODUCTION: Although direct ventricular tachycardia (VT) surgery has been shown to be effective for treatment of inferior myocardial infarction (MI), the differences in the arrhythmia substrates compared to anterior MI have not been systematically delineated. We sought to compare operative procedures and VT substrates between anterior and inferior MI locations. METHODS AND RESULTS: Computerized mapping was performed in 30 patients with a 128-electrode system using epicardial sock and transatrial left ventricular endocardial balloon arrays, followed by combined endocardial resection and cryoablation. At surgery, there were 51 and 34 different VTs in 18 patients with anterior MI and 12 patients with inferior MI, respectively. The proportion of aneurysms was lower in inferior MI (25% vs 78%, P = 0.008). Total activation times accounted for 65% +/- 23% and 50% +/- 22% of the VT cycle length in anterior and inferior infarcts, respectively (P = 0.005). Complete superficial reentry was identified in 12 VTs related to anterior infarcts and in only two VTs associated with inferior infarction (P = 0.038). Involvement of papillary muscles occurred in two patients with inferior MI. Patients with inferior infarcts received more cryolesions and required epicardial cryolesions or mitral valve replacement more frequently, and their operative mortality was greater (2/12 vs 0/18). Noninducibility rate (89.3%) and 2-year survival (76% +/- 8%) did not differ according to infarct location. CONCLUSION: VT associated with inferior MI can be ablated successfully; however, the substrate is more complex, with frequent participation of intramural layers rendering the ablative procedure more difficult.

Adult↗

PubMed1999

Inadequate sympathovagal balance in response to orthostatism in patients with unexplained syncope and a positive head up tilt test.

AIM: To analyse the immediate response of heart rate variability (HRV) in response to orthostatic stress in unexplained syncope. SUBJECTS: 69 subjects, mean (SD) age 42 (18) years, undergoing 60 degrees head up tilt to evaluate unexplained syncope. METHODS: Based on 256 second ECG samples obtained during supine and upright phases, spectral analyses of low (LF) and high frequency (HF) bands were calculated, as well as the LF/HF power ratio, reflecting the sympathovagal balance. All variables were measured just before tilt during the last five minutes of the supine position, during the first five minutes of head up tilt, and just before the end of passive tilt. RESULTS: Symptoms occurred in 42 subjects (vasovagal syncope in 37; psychogenic syncope in five). Resting haemodynamics and HRV indices were similar in subjects with and without syncope. Immediately after assuming the upright posture, adaptation to orthostatism differed between the two groups in that the LF/HF power ratio decreased by 11% from supine (from 2.7 (1.5) to 2.4 (1.2)) in the positive test group, while it increased by 11.5% (from 2.8 (1.5) to 3.1 (1.7)) in the negative test group (p = 0.02). This was because subjects with a positive test did not have the same increment in LF power with tilting as those with a negative test (11% v 28%, p = 0.04), while HF power did not alter. A decreased LF/HF power ratio persisted throughout head up tilt and was the only variable found to discriminate between subjects with positive and negative test results (p = 0.005, multivariate analysis). During the first five minutes of tilt, a decreased LF/HF power ratio occurred in 33 of 37 subjects in the positive group and three of 27 in the negative group. Thus a decreased LF/HF ratio had 89% sensitivity, 89% specificity, a 92% positive predictive value, and an 86% negative predictive value. CONCLUSIONS: Through the LF/HF power ratio, spectral analysis of HRV was highly correlated with head up tilt results. Subjects developing syncope late during continued head up tilt have a decrease in LF/HF ratio immediately after assuming the upright posture, implying that although symptoms have not developed the vasovagal reaction may already have begun. This emphasises the major role of the autonomic nervous system in the genesis of vasovagal (neurally mediated) syncope.

Adolescent↗

PubMed1999

[Mapping and radiofrequency ablation in different forms of right peri-atriotomy flutter].

Peri-atriotomy flutter is a possible complication of surgical atriotomy. This tachycardia in an indication for radiofrequency ablation. The aim of this study was to determine the mechanism of the flutter, evaluate the possibility of mapping and the role of radiofrequency ablation in its treatment. Eleven patients with a mean age of 45 years (26-70) were referred for ablation of atrial flutter observed on average 15 years after surgical atriotomy. In 7 patients (Group I), the ECG appearances before the procedure were that of a rare flutter. Endocavitary mapping showed a circuit limited to the free wall of the right atrium with a posterior caudo-cranial and an anterior cranio-caudal front. A series of radiofrequency applications joining the atriotomy scar to the inferior vena cava interrupted the flutter in all patients and created a bidirectional block around the atriotomy. In 4 patient (Group II), the ECG appearances were that of a common flutter. A series of radiofrequency ablations in the cavo-tricuspid isthmus led to sudden change in polarity of the F wave in all patients. Repeat mapping then showed a peri-atriotomy circuit identical to that described in Group I. The whole was interpreted as a figure-of-eight circuit. The primary success rate was 100%. There were no complications but the early recurrence rate remained high. This preliminary experience confirms the value of radiofrequency ablation in the treatment of peri-atriotomy flutter and shows ECG polymorphism related to a figure-of-eight reentry circuit.

Adult↗

PubMed1998

[Ventricular tachycardia revealing viral myocarditis].

BACKGROUND: The first diagnostic hypothesis in a middle-aged patient presenting with inaugural ventricular tachycardia would be coronary artery disease. If the work-up lacks arguments for this etiology, other cardiac conditions may be involved (dilated cardiopathy, hypertrophic cardiopathy, valve disease arrhythmogenic dysplasia, long QT...). CASE REPORT: A 52-year-old male patient was referred for inaugural ventricular tachycardia. The initial work-up including echocardiography, coronography and the electrophysiologic study provided no explanation. The ventricular tachycardia was later attributed to viral myocarditis. DISCUSSION: Viral myocarditis should always be entertained in patients with unexplained ventricular tachycardia, particular if a viral context is present. In such cases, antibody-labeled scintigraphy is the choice exploration. This noninvasive technique provides determining diagnostic information and helps orient patient management.

Adrenergic beta-Antagonists↗

PubMed1998

Single radiofrequency application to cure atrioventricular nodal reentry: arguments for the slow pathway origin of the high-low frequency slow potentials.

BACKGROUND: High-low frequency slow potentials are thought to be related to the slow AV pathway conduction. Their use was proposed to guide radiofrequency (RF) ablation of atrioventricular nodal reentrant tachycardia (AVNRT). The present study was designed to determine the prospective value of these high-low frequency slow potentials to guide AVNRT ablation using a single RF application. Single RF application could indeed reduce the size of the lesion created in the viciny of the specialized AV conduction system and shorten the radiation exposure and the overall duration of the procedure. RESULTS: Forty-one patients (14 men, 27 women, 45 +/- 16 years old) with AVNRT underwent slow pathway RF ablation guided by high-low frequency slow potentials. High-low frequency slow potentials were found in all patients along the tricuspid annulus and above the coronary sinus. Ablation was always performed in the posterior part of Koch's triangle. The mean A/V amplitude ratio of the successful site was 0.43 +/- 0.59. In 32 patients (78%) AVNRT was no longer inducible after a single RF application. Procedure and radiation times were 35 +/- 31 and 13 +/- 12 min respectively. Five patients required 2, 3 patients 3, and 1 patient 6 RF applications. The mean number of RF applications was 1.4 +/- 0.9 (median = 1). In the 32 patients who required only one RF application, 24 (75%) had an obvious dual AV nodal pathways with a jump before ablation, which completely disappeared in 18 of them (75%) after ablation. In the 6 remaining patients, who still had a jump after 1 RF application, there was no significant change in either conduction times or refractory periods concerning both the anterograde and retrograde AV conduction. No patient had PR interval purlongation. After a mean follow up of 11 +/- 5 months, recurrence was observed in a single patient who received 2 discontinued RF applications. CONCLUSION: Catheter-mediated ablation of AVNRT using high-low frequency slow potentials to localize the slow AV pathway is feasible and safe. Using this technique, a single RF application was successfull in 78% of patients, and slow pathway characteristics were completely eliminated in 75% of patients. The radiation time and the procedure duration were short. This suggest that, in patients with AVNRT, the choice of an appropriate RF target can reduce procedural duration.

Action Potentials↗

PubMed1998

Inadvertent implantation of an ICD lead in the great cardiac vein.

We report an implantable cardioverter defibrillator (ICD) implanted with a single lead inadvertently introduced in the great cardiac vein. No venous lesion was caused by the shocks and the position of the lead remained stable. This case emphasizes the usefulness of different fluoroscopic views during ICD implantation.

Coronary Vessels↗

PubMed1998

Triple chamber pacemaker for end-stage heart failure in a patient with a previously implanted automatic defibrillator.

A 63-year-old man with an ischemic dilated cardiomyopathy previously implanted with an implantable cardioverter defibrillator (ICD) received a triple chamber pacemaker as an ultimate therapeutic resort for end-stage congestive heart failure. After implant, the tolerance to physical exercise increased and NYHA class decreased from III to II. Echocardiography assessed ventricular contraction resynchronization during DDD biventricular pacing as compared to VVI pacing. No major pacemaker-ICD interaction was noted during testing or follow-up. We conclude that sequential biventricular pacing is feasible in the presence of an ICD.

Cardiac Pacing, Artificial↗

PubMed1998

Differential effects of quinidine, flecainide, and cibenzoline on anisotropic conduction in the isolated porcine heart.

INTRODUCTION: Anisotropic conduction characteristics, expressed as the ratio of conduction velocities in the longitudinal (Vl) and transverse (Vt) fiber directions, may play a role in the mechanism of some ventricular tachycardias and is influenced by pharmacologic interventions. Discrepancies exist among the reported orientation-dependent effects of available Class I antiarrhythmic drugs. The aim of this study was to assess the respective effects of quinidine (Class IA), flecainide (Class IC), and cibenzoline (not subclassified) on the anisotropic conduction of porcine hearts, in corroboration of their effects on ventricular action potentials. METHODS AND RESULTS: We studied the actions of 3 and 10 microM quinidine, 1 and 3 microM flecainide, and 0.3 and 1 microM cibenzoline on Vl and Vt determined from 128 electrograms recorded with a plaque electrode on the anterior left ventricle of isolated perfused hearts (spacing 2.5 mm). Vl and Vt were computed from isochronal maps displaying ellipsoid activation during stimulation from the center of the plaque. The effects on the maximal rate of depolarization (Vmax) of action potentials were obtained from ventricular muscle exposed to the same drugs. Flecainide [1 microM] and cibenzoline [0.3 microM] did not alter Vl and Vt significantly. Quinidine [3 microM] predominantly depressed Vl at rapid pacing rates, but the Vl/Vt ratio was not significantly altered. Quinidine [10 microM] and flecainide [3 microM] reduced Vl and Vt in a frequency-dependent fashion. Conversely, cibenzoline [1 microM] mostly decreased Vl and thus decreased the Vl/Vt ratio and increased the Vl/Vt at all pacing rates. This different effect was not related to a greater depressant effect on Vmax CONCLUSION: Quinidine and flecainide act similarly on the anisotropic pattern of conduction (both drugs increase the Vl/Vt ratio), whereas cibenzoline exerts opposite effects. Orientation-dependent effects are different among Class I antiarrhythmic drugs and may be of importance in their therapeutic efficacy or proarrhythmic potential.

Action Potentials↗

PubMed1998

[Dual-chamber implantable automatic defibrillators. Experiences apropos of 16 cases].

In view of the large number of inappropriate shocks observed in patients with implanted defibrillators, improved detection of ventricular arrhythmias has become a major objective. The addition of an atrial catheter has been proposed to improve discrimination between ventricular and non-ventricular arrhythmias. Besides this function, the additional catheter could be used for DDD pacing without risk of interaction between the pacemaker and defibrillator. The authors report their initial experience in 16 patients implanted with a DDD pacemaker. The indication was resuscitated sudden death (N = 5) or ventricular tachycardia (N = 11). The choice of a DDD defibrillator was justified by a bradycardia (N = 9), haemodynamic factors (N = 4) or supraventricular tachycardia (N = 3). The devices used were the Defender 9001 (ELA Medical SA, France, N = 3), the Ventak AV 1810 and the Ventak AV II DR 1821 (Guidant/CPI, Inc. USA, N = 11 and N = 2 respectively). There were three immediate complications. After 2 to 29 months' follow-up, 5 patients had received appropriate treatment by their devices. Five patients had inappropriate shocks : one patient received a shock triggered by electrical interference, two others had no active sensing algorithme when the shocks were delivered, and the other two had an activated algorithme with 1/1 conduction of a supraventricular arrhythmia. No recurrences were recorded after reprogramming the device. DDD or VDD pacing was permanent in 9 patients and intermittent in 3 others. Seven patients had dilated cardiomyopathy and severe cardiac failure and were clinically improved by dual chamber pacing. In many patients, candidates for a defibrillator, this new generation of devices has improved specificity of arrhythmia detection and cardiac pacing without risk of interaction. The authors propose a classification of the indications for a DDD defibrillator.

Algorithms↗