Refractory ventricular tachycardia treated by a second session of stereotactic arrhythmia radioablation.

Purpose: Stereotactic arrhythmia radioablation (STAR) is an effective treatment for refractory ventricular tachycardia (VT), but recurrences after STAR were recently published. Herein, we report two cases of successful re-irradiation of the arrhythmogenic substrate. Cases: We present two cases of re-irradiation after recurrence of a previously treated VT with radioablation at a dose of 20 Gy. The VT exit was localized on the border zone of the irradiated volume, which responded positively to re-irradiation at follow-up. Conclusion: These two cases show the technical feasibility of re-irradiation to control recurrent VT after a first STAR.

[Refractory ventricular tachycardia: Is there a role for radiotherapy?] / Tachycardies ventriculaires réfractaires : quelle place pour la radiothérapie et comment ?

Myocardial scar-related ventricular tachycardia is a serious and potentially life-threatening arrhythmia. The prevention of sudden rhythmic death and ventricular tachycardia recurrence relies on implantable cardioverter defibrillator (ICD), anti-arrhythmic drugs and more recently on radiofrequency catheter ablation. Nevertheless, these approaches have their own risk of adverse events and complications, with a recurrence rate up to 50 % at 2 years. Stereotactic body radiotherapy, delivered in a single dose of 25Gy, has emerged as a new therapeutic tool in the management of highly refractory ventricular tachycardia. In 2017, the very first prospective 5-patient cohort suffering from recurrent ventricular tachycardia on structural heart disease (40 % of ischemic cardiomyopathy) who benefited from cardiac stereotactic body radiotherapy was published. After stereotactic body radiotherapy, the authors observed a strong ventricular tachycardia burden reduction at 12 months, with no major side effects. Since then, around 100 cases have been described in the literature, particularly in the prospective ENCORE-VT study, with positive short- and medium-term outcomes in terms of safety and ventricular tachycardia burden reduction. Recently, another American prospective 5-patient series, published in March 2020, mitigated these results since all patients presented a ventricular tachycardia recurrence at 12 months despite an initial reduction in ventricular tachycardia burden. This article describes the use of stereotactic body radiotherapy in refractory VT, the rationale of the technique, its implementation, preliminary results and potential acute and long-term consequences.

[Periprocedural management of anticoagulation in patients undergoing atrial fibrillation ablation]. / Anticoagulation péri-interventionnelle lors d'ablation de fibrillation auriculaire.

Catheter ablation of atrial fibrillation (AF) has been increasingly performed and has become a standard of care treatment option for drug-refractory symptomatic patients. However, this procedure has been associated with major complications, like thromboembolic or bleeding events. Optimal periprocedural anticoagulation strategy is essential for minimizing these complications. In this article, we review current anticoagulation strategies, including use of oral anticoagulation with Vit-K-Antagonists, as well as use of direct oral anticoagulants in the periprocedural settings of AF ablation.

[Pacing in vasovagal syncope]. / Indications à la stimulation cardiaque dans la syncope vasovagale.

This article presents a critical review of the literature about the potential benefit of cardiac pacing in patients suffering from vasovagal or neurocardiogenic syncope. The manifestation of vasovagal syncope comprises some reflex bradycardia and vasoplegia resulting in cerebral hypoperfusion that ultimately leads to a loss of consciousness. The literature reports conflicting results of the potential benefit of cardiac pacing on the prevention of recurrence of vasovagal events. A detailed analysis of the inclusion criteria of these studies permits to clarify the discrepancy. Only patients older than 50 years with prolonged sinus pause at time of syncope benefit of the implantation of a cardiac pacemaker.

[Percutaneous closure of left atrial appendage: a new hope for patients with atrial fibrillation?]. / Fermeture percutanée de l'auricule gauche: un nouvel espoir pour le patient en fibrillation auriculaire?

Atrial fibrillation (AF) is the most common cardiac arrhythmia. The risk of thromboembolic events is important, and at that time, there is no definite treatment for AF. Oral anticoagulation also represents a hemorrhagic risk factor. Ninety percent of atrial thrombi are located within the left atrial appendage. The percutaneous closure of this left atrial appendage with a device has been shown to decrease thromboembolic events even after interruption of oral anticoagulation as compared to warfarin in a recent randomized study. Recent data support this innovative technique as a reasonable alternative to long term anticoagulation in patients at high risk of bleeding.

Prevalence and determinants of QT interval prolongation in medical inpatients.

BACKGROUND: QT interval prolongation carries an increased risk of torsade de pointes and death. AIM: We sought to determine the prevalence of QT prolongation in medical inpatients and to identify determinants of this condition. METHODS: We enrolled consecutive patients who were admitted to the internal medicine ward and who had an electrocardiogram performed within 24 h of admission. We collected information on baseline patient characteristics and the use of QT-prolonging drugs. Two blinded readers manually measured the QT intervals. QT intervals were corrected for heart rate using the traditional Bazett formula and the linear regression-based Framingham formula. We used logistic regression to identify patient characteristics and drugs that were independently associated with QTc prolongation. RESULTS: Of 537 inpatients, 22.3% had a prolonged QTc based on the Bazett formula. The adjusted odds for QTc prolongation based on the Bazett correction were significantly higher in patients who had liver disease (OR 2.9, 95% CI: 1.5-5.6), hypokalaemia (OR 3.3, 95% CI: 1.9-5.6) and who were taking ≥1 QT-prolonging drug at admission (OR 1.7, 95% CI: 1.1-2.6). Overall, 50.8% of patients with QTc prolongation received additional QT-prolonging drugs during hospitalisation. CONCLUSIONS: The prevalence of QTc prolongation was high among medical inpatients but depended on the method used to correct for heart rate. The use of QT-prolonging drugs, hypokalaemia and liver disease increased the risk of QTc prolongation. Many patients with QTc prolongation received additional QT-prolonging drugs during hospitalisation, further increasing the risk of torsade de pointes and death.

[Cardiology]. / Cardiologie.

The present review provides a selected choice of clinical research in the field of interventional cardiology, electrophysiology and cardiac imaging. We also focused on the new guidelines published by the European society of cardiology in 2010 (revascularization, atrial fibrillation and device therapy in heart failure).

Predictive models of syncope causes in an outpatient clinic.

UNLABELLED: The investigation of unexplained syncope remains a challenging clinical problem. In the present study we sought to evaluate the diagnostic value of a standardized work-up focusing on non invasive tests in patients with unexplained syncope referred to a syncope clinic, and whether certain combinations of clinical parameters are characteristic of rhythmic and reflex causes of syncope. METHODS AND RESULTS: 317 consecutive patients underwent a standardized work-up including a 12-lead ECG, physical examination, detailed history with screening for syncope-related symptoms using a structured questionnaire followed by carotid sinus massage (CSM), and head-up tilt test. Invasive testings including an electrophysiological study and implantation of a loop recorder were only performed in those with structural heart disease or traumatic syncope. Our work-up identified an etiology in 81% of the patients. Importantly, three quarters of the causes were established non invasively combining head-up tilt test, CSM and hyperventilation testing. Invasive tests yielded an additional 7% of diagnoses. Logistic analysis identified age and number of significant prodromes as the only predictive factors of rhythmic syncope. The same two factors, in addition to the duration of the ECG P-wave, were also predictive of vasovagal and psychogenic syncope. These factors, optimally combined in predictive models, showed a high negative and a modest positive predictive value. CONCLUSION: A standardized work-up focusing on non invasive tests allows to establish more than three quarters of syncope causes. Predictive models based on simple clinical parameters may help to distinguish between rhythmic and other causes of syncope.

[Past, present and future of percutaneous catheter ablation technologies for cardiac arrhythmias]. / Passé, present et futur des technologies d'ablation percutanée des arythmies cardiaques.

Drug therapy treatment of cardiac arrhythmias has been disappointing, while percutaneous catheter ablation, efficient and at low risk, has become the first line therapy of the majority of rhythm disturbances, in only two decades. The ultimate challenge, which is atrial fibrillation ablation, is on the way to be successfully solved. This is mainly due to: innovative ablational energy sources; 3D virtual electro-anatomical reconstructions of heart cavities, to map and understand complex arrhythmias' circuits; revolutionary magnetic navigation systems that permit the target positioning of the catheters in the most inaccessible places, even though the operator works at a command board placed away from the patient.

Study of atrial arrhythmias in a computer model based on magnetic resonance images of human atria.

The maintenance of multiple wavelets appears to be a consistent feature of atrial fibrillation (AF). In this paper, we investigate possible mechanisms of initiation and perpetuation of multiple wavelets in a computer model of AF. We developed a simplified model of human atria that uses an ionic-based membrane model and whose geometry is derived from a segmented magnetic resonance imaging data set. The three-dimensional surface has a realistic size and includes obstacles corresponding to the location of major vessels and valves, but it does not take into account anisotropy. The main advantage of this approach is its ability to simulate long duration arrhythmias (up to 40 s). Clinically relevant initiation protocols, such as single-site burst pacing, were used. The dynamics of simulated AF were investigated in models with different action potential durations and restitution properties, controlled by the conductance of the slow inward current in a modified Luo-Rudy model. The simulation studies show that (1) single-site burst pacing protocol can be used to induce wave breaks even in tissue with uniform membrane properties, (2) the restitution-based wave breaks in an atrial model with realistic size and conduction velocities are transient, and (3) a significant reduction in action potential duration (even with apparently flat restitution) increases the duration of AF. (c) 2002 American Institute of Physics.

Heart rate dynamics at the onset of ventricular tachyarrhythmias as retrieved from implantable cardioverter-defibrillators in patients with coronary artery disease.

BACKGROUND: The recent availability of implantable cardioverter-defibrillators (ICDs) that record 1024 R-R intervals preceding a ventricular tachyarrhythmia (VTA) provides a unique opportunity to analyze heart rate variability (HRV) before the onset of VTA. METHODS AND RESULTS: Fifty-eight post-myocardial infarction patients with an implanted ICD for recurrent VTA provided 2 sets of 98 heart rate recordings in sinus rhythm: (1) before a VTA and (2) during control conditions. Three subgroups were considered according to the antiarrhythmic (AA) drug regimen. A state of sympathoexcitation was suggested by the significant reduction in HRV before VTA onset compared with control conditions. beta-Blockers and dl-sotalol enhanced HRV in control recordings; nevertheless, HRV declined before VTA independent of AA drugs. A gradual increase in heart rate and decrease in sinus arrhythmia at VTA onset were specific findings of patients who received dl-sotalol. CONCLUSIONS: The peculiar heart rate dynamics observed before VTA onset are suggestive of a state of sympathoexcitation that is independent of AA drugs.

Two-to-one AV block associated with the congenital long QT syndrome.

INTRODUCTION: Conduction abnormalities associated with long QT syndrome (LQTS) have been reported as "pseudo 2:1 AV block" due to sinus intervals shorter than ventricular refractoriness. METHOD AND RESULTS: We report the electrophysiologic characteristics of a patient suffering from congenital LQTS with episodes of true 2:1 AV block. Induction of 2:1 infra-Hisian blocks and return to 1:1 conduction were observed using single atrial and ventricular extrastimuli. The block was located in the Purkinje network but not in the myocardium. CONCLUSION: The His-Purkinje system of our LQTS patient displayed dynamic properties with a strong increase in refractoriness for short-long sequences and a decrease for long-short sequences that triggered intermittent 2:1 AV blocks.

Subband modeling of the human cardiovascular system: new insights into cardiovascular regulation.

We present a new approach to cardiovascular analysis based on a well-known signal processing technique, namely, the frequency subband decomposition. The subbands are chosen in accordance with physiological standards: (1) 0-0.04 Hz, (2) 0.04-0.15 Hz, (3) 0.15-0.4 Hz. It is shown that such a pre-processing drastically improves the accuracy of the analysis and introduces a new direction in the understanding of the relationships between cardiovascular signals.

Exponential-type distribution of human muscle sympathetic nerve activity results in an automatic quantification method.

A new burst counting method based on a subject invariant characteristic demonstrates the limits of the actual automatic based methods. The exponential behaviour of the counted bursts in function of a variable threshold highlights a scaling property of the muscle sympathetic nerve activity. From experimental single unit recording results, we deduce the exponential-type (gamma) distribution of instantaneous spiking frequency within multi-unit recordings. We show that integrated muscle sympathetic nerve discharges must be gamma distributed with parameters proportional to the number of neurons in the recording pool and to the integration window width.

Autonomic imbalance assessed by heart rate variability analysis in vasovagal syncope.

In this prospective study, the autonomic modulation of the sinus node of 12 patients (mean age 28 +/- 7 years) suffering from vasovagal syncope (VVS) was compared to that of 11 sex and age matched control patients (mean age 32 +/- 4 years) by analysis of heart rate variability. Spectral indices (low frequency power [Plf], high frequency power [Phf], total power [Pt], sympathovagal balance [LF/HF]) and temporal indices, the mean of all coupling intervals between normal beats (mRR), the standard deviation about the mean (sdRR), the percentage of adjacent R to R intervals differing by more than 50 msec (pNN50), and the root mean square of variations in successive R to R intervals (rMSSD) were compared at baseline and during head-up tilt between and within groups. Baseline results were similar in both groups. During tilt testing, comparison of results between groups revealed only significantly higher sdRR and rMSSD and lower LF/HF ratio in VVS patients. Within VVS patients, comparison of temporal and spectral analysis between baseline and tilt showed a significant increase of most indices (Plf, Phf, Pt, sdRR, and rMSSD) but a comparable LF/HF ratio; in contrast, control patients exhibited only a significant increase of LF/HF ratio. In conclusion, VVS patients who developed vasovagal syncope during head-up tilt demonstrated a nonreciprocal modulation of the sinus node by the autonomic nervous system indicative of a pronounced physiological sympathetic surge along with a paradoxical vagal input to the cardiovascular system.

[Primary ventricular fibrillation and early recurrence: apropos of a case of association of right bundle branch block and persistent ST segment elevation]. / Fibrillation ventriculaire primitive et récidive précoce; à propos d'un cas associant bloc de branche droit et sus-décalage persistant du segment ST.

The authors report the case of a 36 year old man who presented with an early recurrence of primary ventricular fibrillation. The initial investigations were normal apart from the finding of complete right bundle branch block with persistent ST segment elevation in the right precordial leads. The recurrence was observed 6 weeks after the initial diagnosis which led to the implantation of an automatic defibrillator. This clinical case is similar to a syndrome recently described of sudden death without obvious cardiac disease but with right bundle branch block and ST segment elevation.