Accuracy of the pacemaker-mediated tachycardia algorithm in Boston Scientific devices.

INTRODUCTION: The incidence of pacemaker-mediated tachycardia (PMT) varies as a function of patient characteristics, device programming and algorithm specificities. We investigated the efficacy of the Boston Scientific algorithm by reviewing PMT episodes in a large device population. METHODS: In this multicenter study, we included 328 patients implanted with a Boston Scientific device: 157 non-dependent patients with RYTHMIQ™ activated (RYTHMIQ group), 76 patients with permanent AV-conduction disorder (AV-block group) and 95 Cardiac Resynchronization Therapy patients (CRT group). For each patient, we reviewed the last 10 remote monitoring-transmitted EGMs diagnosed as PMT. RESULTS: We analyzed 784 PMT episodes across 118 patients. In the RYTHMIQ group, the diagnosis of PMT was correct in most episodes (80%) of which 69% was directly related to the prolongation of the AV-delay associated with the RYTHMIQ algorithm. The usual triggers for PMT were also observed (PVC 16%, PAC 9%). The remainder of the episodes (20%) in RYTHMIQ patients and most episodes of AV-block (66%) and CRT patients (74%) were incorrectly diagnosed as PMT during sinus tachycardia at the maximal tracking rate. The inappropriate intervention of the algorithm during exercise causes non-conducted P-waves, loss of CRT (sustained in six patients) and may have been pro-arrhythmogenic in one patient (induction of ventricular tachycardia). CONCLUSION: Algorithms to minimize ventricular pacing can occasionally have unintended consequences such as PMT. The PMT algorithm in Boston Scientific devices is associated with a high rate of incorrect PMT diagnosis during exercise resulting in inappropriate therapy with non-conducted P-waves, loss of CRT and limited risk of pro-arrhythmic events.

[Senegal's experience with pacemakers re-use : about 161 patients at the Aristide Le Dantec university hospital center]. / Expérience du Sénégal sur les pacemakers reconditionnés : à propos de 161 patients au centre hospitalo-universitaire Aristide Le Dantec.

INTRODUCTION: The reuse pacemakers is a beneficial technique for patients in countries with a low economic standard of living where health care is almost non-existent. We offered to share the experience of Senegal on the reconditioning of pacemakers. METHODOLOGY: We conducted a retrospective study over a period from January 2015 to December 2020 including all patients who benefited from a reconditioned pacemaker for primary implantation or reimplantation. The criteria for reconditioning pacemakers are the absence of dysfunction or damage and a residual battery life of more than 5 years of the pacemaker. Refurbished pacemakers are acquired either from deceased families or from extraction centers. Sterilization is carried out using phenoxypropanol + benzalkonium chloride solution, 70% ethanol and ethylene oxide. RESULTS: We collected 161 patients during the study period, including 77 men (48%) and 84 women (52%), i.e. a M/F sex ratio of 0.94. The average age of the population was 65 years. Functional symptomatology was dominated by syncope in 54%. Electrocardiographically, 72% of patients were in complete atrioventricular block. A primary implantation was noted in 91.5% of patients. The vascular approach most used during implantation was cephalic in 49.5% of cases. In our series, we noted that 58% of patients had benefited from temporary stimulation before implantation. At implantation, single-chamber stimulation was used in 60% of patients and 46.5% of patients had programming in VVI mode. We had 5.5% major complications with 3% box infection occurring between 3 and 6 months post-implantation and 2.5% pacemaker syndrome. We noted 1 case of death linked to underlying heart disease. CONCLUSION: Reconditioning of cardiac pacemakers is a safe and beneficial therapeutic strategy for patients. In Senegal, reconditioning has shown satisfactory results. In our countries this technique can be an alternative for certain patients.

A new gastric impedancemeter for detecting the development of a visceral edema: a proof-of-concept study on an experimental endotoxemic shock.

Visceral congestion and edema are important features of advanced heart failure. Monitoring the evolution of fluid content in the gastric wall might provide an index of the development of this phenomenon and therefore constitute an innovative marker to early detect acute decompensated heart failure episodes. The evolution of the fluid content in the gastric wall is measured using a device implanted in the submucosa layer of the fundic region of the stomach. The device composed of two electrodes measures the bioimpedance values that reflects the water content of the tissue.An in-vivo experiment in a pig was carried out to validate the feasibility of detecting the gastric bioimpedance variations during the development of an experimental acute visceral edema caused by an endotoxemic shock. Our preliminary results confirm the possibility to monitor the bioimpedance variations due to moderate changes in tissue water content (10%) with a two-electrode configuration device implanted in the submucosa of the stomach.

[Significance of the contralateral approach combined with venous deocclusion in a case of biventricular defibrillator implantation]. / Intérêt de l'abord controlatéral associé à une désobstruction veineuse en cas d'implantation d'un défibrillateur biventriculaire.

The authors report the case of a patient in whom a biventricular defibrillator was successfully implanted from the right, following a failed approach from the left. The patient had chronic thrombosis of the subclavian vein, and this procedure was only possible after venous deocclusion and the positioning of an endoprosthesis. The authors underline the significance of the contralateral approach in case of difficulties in inserting pacing devices, as well as the complementary benefits of interventional radiological procedures in order to allow vascular access in cases of chronic venous thrombosis.

Arrhythmic cardiac arrest due to isolated coronary artery spasm: long-term outcome of seven resuscitated patients.

OBJECTIVES: Our aim was to look at the clinical features and long-term follow-up of seven patients without coronary artery disease, who had a history of life-threatening ventricular arrhythmias due to coronary spasm. BACKGROUND: Arrhythmic cardiac arrest due to isolated coronary spasm is rare, and there is limited information on the patients affected by this entity alone. METHODS: The seven patients were recruited retrospectively from a cohort of survivors of cardiac arrest. None had a history of angina pectoris, structural heart disease or significantly narrowed coronary segments. All had a positive ergonovine provocation test result. RESULTS: The patients' mean age was 44 years; three were male and four female. All were habitual cigarette smokers. No arrhythmias were induced on programmed ventricular stimulation; corrected QT interval (QTc) and corrected JT interval (JTc) dispersion were within normal ranges. After the ergonovine provocation test, treatment with calcium channel blocking agents (diltiazem, verapamil, nifedipine or amlodipine) was initiated at a dose determined by titration until a negative test result was obtained. At a mean follow-up interval of 58 months for the total group, six patients remained free of symptoms, whereas the one patient who did not stop smoking had a new cardiac arrest despite treatment for coronary spasm. CONCLUSIONS: A favorable long-term outcome may be expected in survivors of cardiac arrest due to coronary spasm, in the absence of significant coronary artery disease. Calcium channel blockers are the most appropriate therapy in these patients. These observations provide further evidence for the role of silent ischemia in cardiovascular death.

[Pacemaker and intra cardiac defibrillator lead extraction techniques]. / Les techniques de remplacement de matériel de stimulation cardiaque et défibrillation implantable.

Percutaneous Pace-maker and ICD lead extraction techniques has been developped: by superior approach using locking stylet and more and more efficient outher sheats (laser assisted); and also by femoral approach using double lasso catheters (Needle's eye snare). Indication range has increased and is not only reserved for lead infection. Because of scar tissue holding the lead and also the impact of the distal tip, those techniques are not simples. Extraction recommandations do advise those procedures to be performed by expert physicians, in cardiac surgery centers, where complications can be managed and reduced. The use of laser assisted outher sheats will make lead extraction easier and will reduce complication rate. Alternative procedure in case of failure with superior approach remain femoral approach. All those techniques give a success rate of about 98 % for percutaneous lead extraction in an expert center.

[A new diagnostic concept in cardiac pacing for the evaluation of the incidence of atrial arrhythmias. Results of the AIDA study]. / Un nouveau concept diagnostique en stimulation cardiaque pour évaluer l'incidence des arythmies atriales. Résultats de l'étude AIDA.

An international, prospective, multicentre trial (AIDA) was undertaken from October 1995 to March 1997. The object was to compare the diagnosis of atrial arrhythmias (AA) by the automatic interpretation of the memory functions of dual chamber pacemakers with that of 24 hour Holter monitoring at day 1. The second objective was to assess the incidence and symptomatology of the AA during follow-up at Day 28. In France, 226 patients implanted with Chorus, Chorus II and Chorus RM pacemakers were included in the study (148 men, 70.5 +/- 10.8 years) for the following indications: AVB (atrioventricular block)/bundle branch block (47.3%), sinus mode dysfunction (10.2%), bradycardia-tachycardia syndrome (10.2%), AVB + sinus node dysfunction + cardia-tachycardia syndrome (19.5%), other (2.2%). AA were documented in 34.5% of patients before implantation. Of the 226 patients analysed at Day 1, 23 (10.2%) had at least one episode of AA diagnosed simultaneously by Holter monitoring and the automatic interpretation (AIDA). These AA were atrial fibrillation (15 patients), atrial flutter (2 patients) and atrial tachycardia (6 patients). The sensitivity of the AIDA programme for detecting AA was 92% and the specificity 97%. Of the 156 patients evaluated at Day 28, the programme diagnosed AA in 78 patients (50%), 34 of which (21.8%) were asymptomatic and without previously documented AA. The results of the AIDA study confirmed the excellent sensitivity and specificity of the memory functions of these cardiac pacemakers for analysis of AA. They seem to be very common during the follow-up of pacemaker-equipped patients. This new diagnostic concept will facilitate the programming and study of the efficacy of anti-arrhythmic therapy prescribed during long-term follow-up.

[Value of memory functions in implantable prostheses]. / Apport des mémoires embarquées dans les prothèses implantables.

The development of memory functions with memorised electrogrammes is one of the most important technical advances in cardiac pacemakers and defibrillators. These memory functions are very useful in the management of patients with implanted prostheses. In the case of defibrillators, the memory allows evaluation and validation of appropriate treatments (shock or asymptomatic antitachycardia stimulation) or inappropriate function. The memory can also help assess the efficacy of complementary antiarrhythmic therapy or radiofrequency ablation. The incorporation of memory functions in pacemakers is more recent but no less useful. The latest generation of pacemakers have not only a therapeutic but also a diagnostic role with respect to atrial and ventricular arrhythmias. They can lead to the prescription of an antiarrhythmic or anticoagulant drug in cases of sustained atrial fibrillation confirmed by the memorised electrogrammes. The memory function is also a great aid in reprogramming stimulators in cases of overdetection (V-A cross talk). They may also be activated by the patient in cases of sporadic paroxysmal symptoms. The latest development is that of a purely diagnostic prosthesis: the implantable Holter, whose main indication is in the investigation of unexplained syncope.

[Localised primary lesion of the right pulmonary artery in Takayasu's disease]. / Atteinte primitive localisée à l'artère pulmonaire droite d'une maladie de Takayasu.

Takayasu's disease involves the pulmonary vessels in over 50% of cases. However, primary lesions of the pulmonary arteries are very rare. The authors report the cases of a 34 year-old Caucasian woman presenting with clinical and radiological signs of acute pulmonary embolism, but in whom the pulmonary angiography showed stenotic and occlusive lesions of the right pulmonary artery. MRI provided an accurate diagnosis by showing typical thickening of the pulmonary arterial walls.

[Role of atrial stimulation in the treatment of paroxysmal atrial fibrillation]. / Place de la stimulation auriculaire dans le traitement de la fibrillation auriculaire paroxystique.

Preventive treatments for atrial fibrillation by stimulation have been developed for several years now, mainly due to the relative failure of anti-arrhythmic treatments. They are based on the hypothetical effects of stimulation by controlling cardiac frequency, abolishing bradycardia-dependent extrasystoles, by the inhibition of atrial automatic foci with "overdrive", and by the modification of intra- or inter-atrial conduction delays as well as by remodelling the arrhythmogenic substrate. It is clear that an undeniable effect exists for the prevention of atrial fibrillation, even for the risk of cerebral vascular accident, by physiological stimulation (DDD/DDDR) compared to pure ventricular stimulation (VVI/VVIR) in a heterogenous global population of stimulated patients. For the moment, there is not sufficient proof of a positive effect for the emerging sites of cardiac stimulation, either atrial mono-site or double site in the populations at high risk of atrial fibrillation, with or without associated bradycardia. Some new prevention algorithms by "overdrive" are under development but for the moment only a few preliminary studies seem to show a slight benefit. It is clear that at present stimulation should be reserved only for cases of atrial fibrillation associated with a classic indication for implantation. In these patients it is recommended to position the probes in an optimal manner in order to counteract conduction disorders, choosing an adapted double chamber stimulator with prevention algorithms. That said, the patient should be clearly warned that the long term success rate is no more than 50%.

[A rare cause of inappropriate shocks of an implantable automatic defibrillator. Twiddler syndrome]. / Une cause rare de chocs inappropriés d'un défibrillateur automatique implantable. Le Twiddler's syndrome.

The authors report the case of a patient with an automatic defibrillator implanted by an endocavitary approach. The device emitted a series of inappropriate shocks. They were triggered by the detection of myopotentials resulting from lesions of the lead due to Twiddler's syndrome. This was reproduced by telemetry in real time and confirmed by chest and abdominal X-ray and the peroperative findings. Treatment consisted of ablation of all implanted material which was replaced by a new retropectoral model.

[Quantification of mitral valve insufficiency by Doppler echocardiography. Correlation with cine-angiography in 60 patients]. / Quantification de l'insuffisance mitrale par échocardiographie Doppler. Corrélations avec la ciné-angiographie chez 60 patients.

Non-invasive quantification of mitral regurgitation remains a clinical problem. The aim of this study was to assess a new methodology of Doppler echocardiographic assessment of the mitral regurgitant fraction. The study included 60 patients (average age 61 years) in sinus rhythm with mitral regurgitation. The cardiac output was measured by Doppler echocardiography at four sites: the aortic, pulmonary and mitral rings and at the tips of the mitral leaflets by a method previously validated and published. Using the average of the aortic and pulmonary cardiac outputs on the hand and the mitral cardiac output on the other, it was possible to calculate the regurgitant fraction: (mean mitral flow-mean aortic/pulmonary flow)/mean mitral flow. This was correlated with the Sellers angiographic grades of regurgitation. The results confirm this validated procedure: the correlation of aortic and pulmonary flows was good: r = 0.94. This also held true for mitral flow at the two sites: r = 0.96. The correlation between the Doppler echocardiographic regurgitant fraction and the angiographic estimation of the severity of mitral regurgitation was good: r = 0.89. There was a statistically significant difference between the Doppler echocardiographic regurgitant fractions corresponding to Sellers Grades I, II and III mitral regurgitation (p = 0.0001). This study shows that Doppler echocardiographic measurements of blood flow at different orifices of the heart applied to the quantification of mitral regurgitation is a reliable method, the use of which, with strict methodological criteria, may be proposed in everyday clinical practice.

[Feasibility and accuracy of pulmonary blood flow measurement by Doppler echocardiography. Apropos of 100 consecutive cases]. / Faisabilité et précision de la mesure du débit pulmonaire par méthode échocardiographique Doppler. A propos de 100 cas consécutifs.

One of the main advantages of Doppler echocardiography is the possibility of non-invasive measurement of blood flow at each valvular orifice. This method enables quantification of valvular regurgitation, the measurement of Qp/Qs in cardiac disease with atrial or ventricular shunts, and the interpretation of gradients and functional surface areas in valvular stenosis or prosthesis with respect to the underlying haemodynamics. In each of these application, the measurement of pulmonary blood flow is valuable as the reference blood flow, and even indispensible in cases of shunts. The authors' objective was to study the feasibility and accuracy of pulmonary flow measurement in 100 consecutive patients (40 women and 60 men, average age 56.7 +/- 17.5 years) with cardiac disease (82%) or healthy hearts (18%). A grading from A to D was accorded depending on the technical difficulty of the examination, each grade having three degrees: 1) difficulty of recording and poor quality Doppler spectrum, 2) difficulty of measuring orifice diameter by 2D echocardiography, 3) necessity of analysis of color coded anterograde flow to measure the pulmonary valvular orifice. Grade A was distributed to easily recordable measurements with no difficulty; grade B for measurements with one difficulty; grade C for measurements with 2 difficulties and grade D for investigations judged to be impossible or unreliable (3/3 criteria). The feasibility of measurement of the cardiac output at the pulmonary orifice was 88% (A:55%, B:25%, C:8%). The correlation between the pulmonary flow and reference measurements at the aortic and/or mitral valve and/or mitral annulus was 0.96. The average difference between the pulmonary and reference flow was 51 +/- 273 cc/min.(ABSTRACT TRUNCATED AT 250 WORDS)

[Left ventricular diastolic function: value of its study with mitral and pulmonary venous Doppler phonocardiography and apexography]. / La fonction diastolique ventriculaire gauche: intérêt de son étude par le doppler mitral, le doppler veineux pulmonaire, le phonocardiogramme et l'apexogramme.

The study of mitral flow and pulmonary venous flow by Doppler provides a non-invasive method of assessing diastolic function. But there are difficulties in differentiating normal pattern from "pseudo-normal" (Appleton Type II) (E/A Mitral > 1). Phonocardiography enables the recording of early (B3) and late (B4) diastolic gallops. The apexogramme enables calculation of the a/H and D/H ratios (amplitude of the "D" wave resulting from rapid early diastolic filling to the total amplitude of the apexogramme). These two techniques record pulsatile phenomena ("pulse waves") arising from variations in intra-left ventricular pressure. They may complete the interpretation of Doppler recordings of velocities of blood flow ("flow waves"). To evaluate the value of each technique, the authors studied left ventricular diastolic function by Doppler phonocardiography and apexography in 60 subjects (38 patients of which 30 with ischaemic heart disease, and 22 healthy subjects). The results showed that increase in velocity and deceleration slope of the Doppler mitral E wave was associated with the presence of a B3 and correlated (r = 0.60; p = 0.0001) with the D/H ratio of the apexogramme. On the other hand, the absence of correlation between the mitral A wave velocity and a B4 associated with an increased a/H ratio enables the differentiation of normal Doppler mitral flow (absence of B4, Doppler a/H ratio < 12%) from pseudo-normal appearances (B4, a/H ratio > 12%). Therefore, the evaluation of diastolic function by Doppler mitral and pulmonary venous flow analysis may be usefully completed by phonocardiography and apexography.

[Clinical evaluation after myocardial infarction. Its role, date and methods]. / Evaluation clinique après infarctus du myocarde. Sa place, sa date, les moyens.

Although global mortality in the year following myocardial infarction is about 10%, this figure varies from less than 1% to more than 50% in some very high risk cases. The principal objective of clinical evaluation during the acute phase is to establish a prognosis and propose a rational strategy for myocardial revascularisation (by bypass grafting or angioplasty) in patients with a poor prognosis. An essential feature of this evaluation is to reduce health care costs and hospital stay to a minimum. Coronary angiography is the only investigation which allows assessment of the coronary circulation and is probably the best method of evaluating global and regional left ventricular function, two essential prognostic factors: on the other hand, it does not provide information about the presence of residual ischaemia or persistent myocardial viability in the infarcted territory. Some very high risk patients should undergo systematic coronary angiography to determine the possibilities for myocardial revascularisation: early post-infarction angina, left ventricular failure, chronic angina, elderly but valid patients... The indications of coronary angiography should also extend to patients with non-Q wave infarction, to young patients with myocardial infarction on thrombolysed infarcts: results of coronary angiography should then be compared with those of standard exercise stress testing. It is only in other situations, concerning a minority of patients, in which two attitudes may be considered: the first, to perform coronary angiography very early (within 24-48 hours of admission) allowing early discharge from hospital of many cases, completed later by standard exercise stress testing: any revascularisation procedure is considered at that time and requires a second hospital admission. The second attitude consists in performing coronary angiography between the 7th and 10th day only if some paraclinical changes are present: exercise stress testing then has an essential role; to improve its negative predictive value for absence of long-term coronary events it should be associated with radionuclide investigation of myocardial perfusion (thallium, MIBI) or with an evaluation or residual myocardial viability (labelled fatty acids, cyclotron). This attitude also allows early identification of "good candidates" for myocardial revascularisation.

[Quantification of aortic insufficiencies. Comparison between Doppler echocardiography and qualitative angiographic methods: apropos of a series of 60 consecutive patients]. / Quantification des insuffisances aortiques. Comparaison entre méthodes échocardiographie doppler et angiographie qualitative; à propos d'une série de 60 patients consécutifs.

Many doppler echocardiographic indices have been described for quantifying aortic regurgitation, posing the problem of the relative value of each. Therefore, the authors assessed the severity of aortic regurgitation in 60 consecutive patients (16 women and 44 men, mean age 56.7 years, range 7 to 84 years) by the four grades of Seller's classification with selective aortography. These results were compared with Doppler echocardiographic measurement of anterograde cardiac output (Qao), the pressure half time (PHT), diameter of the jet at its origin in M mode colour Doppler (DTM) and calculation of the regurgitant fraction (RF) by comparison of flow at the different cardiac orifices by a method previously described and validated in the author's laboratory with an interorifice correlation of 0.91 to 0.96 and confidence intervals at 95% of the order of 12%. The feasibility of doppler echocardiographic methods was good: 87.8% for PHT (58/66 patients), 90% for DTM (36/40 patients), 90.9% for Qao and RF (60/66 patients). The correlation with aortography was -0.65 (p < 0.01) for PHT; 0.91 (p < 0.01) for DTM, 0.80 (p < 0.01) for Qao and 0.92 (p < 0.005) for RF. However, there was a number of overlaps between Grades I and II and Grades III and IV.(ABSTRACT TRUNCATED AT 250 WORDS)

[Ventricular tachycardia by branch to branch re-entry. Familial case with Steinert's disease]. / Tachycardie ventriculaire par réentrée de branche à branche. Cas familial avec maladie de Steinert.

Ventricular tachycardia by branch to branch reentry is a rare arrhythmia. It occurs in cardiomyopathies associated with conduction defects. During tachycardia a His potential precedes each QRS complex which usually has a left bundle branch block appearance. The authors report two familial cases of ventricular branch to branch tachycardia (son and mother) without cardiomyopathy. The diagnosis of Steinert's disease was made post-mortem in these two patients. In cases of branch to branch ventricular tachycardia, the diagnosis of myotonic dystrophy should be excluded. Conversely, endocavitary electrophysiological investigation with ventricular stimulation should be proposed for symptomatic patients (dizzy spells, syncope) to diagnose branch to branch ventricular tachycardia, even in cases with conduction defects which could also explain the symptoms.