Temporary transvenous VDD pacing as a bridge to permanent pacemaker implantation in patients with sepsis and haemodynamically significant atrioventricular block.

AIMS: Permanent pacemaker (PM) implantation is temporarily contraindicated in patients (pts) with sepsis. In patients with symptomatic atrioventricular (AV) block and infection, prolonged VVI pacing is therefore usually ensured by a ventricular pacing lead (PL) connected to an external PM generator. In patients with normal sinus function and heart failure, the VVI mode can exacerbate haemodynamic dysfunction. A single AV PL can be attractive to achieve physiological pacing. This study was designed to assess the efficacy and safety of temporary VDD pacing as a bridge to permanent PM implantation in patients with complete AV block until control of infection. METHODS AND RESULTS: This study included eight patients with complete AV block and sepsis with negative blood culture. Due to the presence of congestive heart failure, a single bipolar AV PL connected to an external VDD PM generator. At VDD implantation, P-wave amplitude was 1.9 ± 1.6 mV and R-wave was 11.3 ± 5.2 mV. The ventricular pacing threshold was 0.53 ± 0.1 V for a 0.5 ms pulse. Antibiotic therapy was instituted in all patients. A permanent VDD or DDD PM was implanted after 8 ± 2.5 days of temporary VDD pacing. At permanent PM implantation, the mean brain natriuretic peptide level had decreased and sepsis was controlled in all patients. No recurrence of sepsis was observed with a mean follow-up of 15.8 ± 5.3 months. CONCLUSION: Temporary VDD pacing is a safe and effective method to achieve prolonged AV physiological pacing in patients with AV block until infection has been controlled.

Catheter ablation in adults with congenital heart disease: A 15-year perspective from a tertiary centre.

BACKGROUND: With the growing adult congenital heart disease (ACHD) population, the number of catheter ablation procedures is expected to dramatically increase. Data reporting experience and evolution of catheter ablation in patients with ACHD, over a significant period of time, remain scarce. AIM: We aimed to describe temporal trends in volume and outcomes of catheter ablation in patients with ACHD. METHODS: This was a retrospective observational study including all consecutive patients with ACHD undergoing attempted catheter ablation in a large tertiary referral centre over a 15-year period. Acute procedural success rate and freedom from recurrence at 12 and 24 months were analysed. RESULTS: From November 2004 to November 2019, 302 catheter ablations were performed in 221 patients with ACHD (mean age 43.6±15.0 years; 58.9% male sex). The annual number of catheter ablations increased progressively from four to 60 cases per year (P<0.001). Intra-atrial reentrant tachycardia/focal atrial tachycardia was the most common arrhythmia (n=217, 71.9%). Over the study period, acute procedural success rate increased from 45.0% to 93.4% (P<0.001). Use of irrigated catheters (odds ratio [OR] 4.03, 95% confidence interval [CI] 1.86-8.55), a three-dimensional mapping system (OR 3.70, 95% CI 1.72-7.74), contact force catheters (OR 3.60, 95% CI 1.81-7.38) and high-density mapping (OR 3.69, 95% CI 1.82-8.14) were associated with acute procedural success. The rate of freedom from any recurrence at 12 months increased from 29.4% to 66.2% (P=0.001). Seven (2.3%) non-fatal complications occurred. CONCLUSIONS: The number of catheter ablation procedures in patients with ACHD has increased considerably over the past 15 years. Growing experience and advances in ablative technologies appear to be associated with a significant improvement in acute and mid-term outcomes.

Phrenic nerve stimulation in cardiac resynchronization therapy.

In cardiac resynchronization therapy (CRT), the electrical impulse delivered by the left ventricular (LV) lead may incidentally cause phrenic nerve stimulation (PNS). The purpose of this state-of-the-art review is to describe the frequency, risk factors, and clinical consequences of PNS and to present the most recent options to successfully manage PNS. PNS occurs in 2 to 37% of implanted patients and is not always detected in the supine position during implantation. Lateral and posterior veins are at higher risk of PNS than anterior veins, and apical positions are at higher risk of PNS than basal positions. The management of PNS discovered during implantation may include mapping the course of the target vein in order to find a PNS-free site, targeting another vein if available, and pacing with alternative configurations before changing the lead location. Non-invasive options for management of post-operative PNS depend on the difference between PNS and LV stimulation thresholds and include reducing the LV pacing output, automatic determination of LV stimulation threshold and minimal output delivery by the device, increasing the pulse duration, and electronic repositioning. New quadripolar leads allow to pace from different cathodes, and the multiple pacing configurations available have proved superior to bipolar leads in mitigating PNS. This electronic repositioning addresses almost all of the clinically relevant PNS and should markedly reduce the need for invasive lead repositioning or CRT abandon, which is actually the last option for 2% of patients.

Fuzzy logic-based diagnostic algorithm for implantable cardioverter defibrillators.

OBJECTIVE: The paper presents a diagnostic algorithm for classifying cardiac tachyarrhythmias for implantable cardioverter defibrillators (ICDs). The main aim was to develop an algorithm that could reduce the rate of occurrence of inappropriate therapies, which are often observed in existing ICDs. To achieve low energy consumption, which is a critical factor for implantable medical devices, very low computational complexity of the algorithm was crucial. The study describes and validates such an algorithm and estimates its clinical value. METHODOLOGY: The algorithm was based on the heart rate variability (HRV) analysis. The input data for our algorithm were: RR-interval (I), as extracted from raw intracardiac electrogram (EGM), and in addition two other features of HRV called here onset (ONS) and instability (INST). 6 diagnostic categories were considered: ventricular fibrillation (VF), ventricular tachycardia (VT), sinus tachycardia (ST), detection artifacts and irregularities (including extrasystoles) (DAI), atrial tachyarrhythmias (ATF) and no tachycardia (i.e. normal sinus rhythm) (NT). The initial set of fuzzy rules based on the distributions of I, ONS and INST in the 6 categories was optimized by means of a software tool for automatic rule assessment using simulated annealing. A training data set with 74 EGM recordings was used during optimization, and the algorithm was validated with a validation data set with 58 EGM recordings. Real life recordings stored in defibrillator memories were used. Additionally the algorithm was tested on 2 sets of recordings from the PhysioBank databases: MIT-BIH Arrhythmia Database and MIT-BIH Supraventricular Arrhythmia Database. A custom CMOS integrated circuit implementing the diagnostic algorithm was designed in order to estimate the power consumption. A dedicated Web site, which provides public online access to the algorithm, has been created and is available for testing it. RESULTS: The total number of events in our training and validation sets was 132. In total 57 shocks and 28 antitachycardia pacing (ATP) therapies were delivered by ICDs. 25 out of 57 shocks were unjustified: 7 for ST, 12 for DAI, 6 for ATF. Our fuzzy rule-based diagnostic algorithm correctly recognized all episodes of VF and VT, except for one case where VT was recognized as VF. In four cases short lasting, spontaneously ending VT episodes were not detected (in these cases no therapy was needed and they were not detected by ICDs either). In other words, a fuzzy logic algorithm driven ICD would deliver one unjustified shock and deliver correct therapies in all other cases. In the tests, no adjustments of our algorithm to individual patients were needed. The sensitivity and specificity calculated from the results were 100% and 98%, respectively. In 126 ECG recordings from PhysioBank (about 30min each) our algorithm incorrectly detected 4 episodes of VT, which should rather be classified as fast supraventricular tachycardias. The estimated power consumption of the dedicated integrated circuit implementing the algorithm was below 120nW. CONCLUSION: The paper presents a fuzzy logic-based control algorithm for ICD. Its main advantages are: simplicity and ability to decrease the rate of occurrence of inappropriate therapies. The algorithm can work in real time (i.e. update the diagnosis after every RR-interval) with very limited computational resources.

Femoral vein thrombosis after right-sided electrophysiological procedures.

PURPOSE: Electrophysiological studies and radiofrequency catheter ablations require single or multiple sheath placements through femoral vein cannulation. The objective of this study was to determine the incidence, predictors, and outcomes of deep vein thrombosis (DVT) following such procedures. METHODS AND RESULTS: We prospectively enrolled 220 consecutive patients with a median age of 70 [60-79] years. The median duration of the procedures from insertion to removal of sheaths was 45 [30-75] min. At least two sheaths were inserted in 158 (72%) of the cases. Duplex ultrasonography evaluation of the lower leg veins was performed 6 h after the procedure and revealed common femoral vein thrombosis in 11 (5%) patients. All thrombi were partial and none was complete. Thrombi were mobile in four patients and extended to the external iliac vein in three patients. None of the patients presented with clinical signs of DVT or pulmonary embolism. Anticoagulation was prescribed for 2-4 weeks and a follow-up duplex ultrasonography obtained in the first seven patients revealed complete resolution of thrombi in all cases. On multivariate analysis, two predictors of thrombosis occurrence were identified: a greater sum of sheath diameters (odds ratio, 1.41 [95% confidence interval, 1.25-1.60] per 1-French increase; p < 0.001) and a longer procedural duration (odds ratio, 1.02 [95% confidence interval, 1.00-1.04] per 1-min increase; p = 0.04). CONCLUSIONS: Asymptomatic femoral DVT occur in 5% of electrophysiological studies and right-heart radiofrequency catheter ablations, particularly when large sheaths are inserted for a longer period. The role of anticoagulation in this clinical setting warrants further evaluation.

Determinants of mortality in patients undergoing cardiac resynchronization therapy: baseline clinical, echocardiographic, and angioscintigraphic evaluation prior to resynchronization.

BACKGROUND: In dilated cardiomyopathy (DCM) patients (pts) with cardiac resynchronization therapy (CRT) for ventricular dyssynchrony, long-term predictors of mortality and morbidity remain poorly investigated. METHOD AND RESULTS: We reviewed data of 102 pts, 68 +/- 10 years, NYHA Class II-IV (14 Class II, 67 Class III, 21 Class IV), who benefited from CRT (69 CRT, 33 CRT-ICD). Fifty-two patients had an ischemic DCM, 36 a previously implanted conventional PM/ICD, 29 a permanent atrial fibrillation, and 19 needed dobutamine in the month preceding implant. QRS duration was 187 +/- 35 ms, left ventricular end-diastolic diameter 72 +/- 10 mm, mitral regurgitation severity 1.9 +/- 0.8, echographic aorto-pulmonary electromechanical delay 61.5 +/- 25 ms and septo-lateral left intraventricular delay 86 +/- 56 ms, pulmonary artery pressure (PAP) 43 +/- 11 mmHg, angioscintigraphic left ventricular ejection fraction (EF) 20 +/- 9%, and right ventricular EF 30.5 +/- 14%. Over a mean follow-up of 23 +/- 20 months, 26 pts died (18 heart failures (HFs), 1 arrhythmic storm, 7 noncardiac deaths). Positive univariate predictors of death from any cause were NYHA Class IV (P < 0.001), and need for dobutamine the month preceding CRT (P < 0.008), while use of beta-blocking agents (P < 0.08) and left ventricular EF (P < 0.09) were negative ones. NYHA Class IV was the only independent predictor at multivariate analysis (P < 0.01). Survival at 24 months was 85% in Class II, 80% in Class III, and 37% in Class IV (II vs III, P = ns; III vs IV, P < 0.001). When using a composite endpoint of death from any cause and unplanned rehospitalization for a major cardiovascular event, there were 48 events (14 HF deaths, 3 noncardiac deaths, 26 HF rehospitalizations, 2 paroxysmal atrial fibrillation, 2 sustained ventricular tachycardia, 1 nonfatal pulmonary embolism). Predictors of death from any cause/unplanned rehospitalization for a major cardiovascular event in the follow-up were NYHA Class IV (P < 0.001), need for dobutamine during the month preceding CRT (P < 0.002), and PAP (<0.02). NYHA Class IV was the only independent predictor at multivariate analysis (P < 0.05). Event-free proportion at 24 months was 70% in Class II, 64% in Class III, and 37% in Class IV (II vs III, P = ns; III vs IV, P < 0.01). When considering determinants of mortality only in NYHA Class IV patients, no variable was significantly correlated to mortality. Need for dobutamine during the last month preceding CRT did not add an adjunctive mortality risk. CONCLUSION: Baseline NYHA Class IV at implantation appears as the most important determinant of a poor clinical outcome in terms of both mortality and morbidity. No predictive criteria seem available for NYHA Class IV patients, in order to discriminate who will die after CRT and who will not. NYHA Class IV strongly influences the clinical outcome, suggesting that, in future studies planned on mortality and rehospitalization as major endpoints, baseline NYHA Class IV should be separately taken into account.

Long-term experience with a preshaped left ventricular pacing lead.

This study describes a long-term experience with a new LV pacing lead. The study population consisted of 62 patients (85% men, 71 +/- 10 years old) with advanced dilated cardiomyopathy, in NYHA Class III or IV despite optimal drug therapy, and a QRS duration > 150 ms. Patients in sinus rhythm were implanted with a triple chamber pacemaker to maintain atrioventricular synchrony. A dual chamber pacemaker was implanted in patients in atrial fibrillation for biventricular pacing only. A clinical evaluation and interrogation of the resynchronization pacemaker were performed at implant, at 1 week (W1), one (M1), four (M4), and seven (M7) months after implantation. A longer follow-up (2 years) is available for patients implanted at the authors institution. LV measurements were pacing threshold at 0.5-ms pulse duration and pacing impedance. R wave amplitude (mV) was measured at the time of implantation only. The system was successfully implanted in 86% of patients with the latest design of the lead. Mean R wave amplitude at implant was 15 +/- 7 mV and mean pacing impedance was 1054 +/- 254 omega. Between implant (n = 38) and M7 (n = 15), pacing threshold rose from 0.73 +/- 0.54 to 1.57 +/- 0.60 V (P < 0.001). In conclusion, the situs lead was successfully implanted in a high percentage of patients. In addition, low pacing threshold and high impedance measured during follow-up are consistent with a low pacing current drain, ensuring a durable pulse generator longevity.

Basal asynchrony and resynchronization with biventricular pacing predict long-term improvement of LV function in heart failure patients.

Biventricular pacing (BiV) is emerging for patients with dilated cardiomyopathy (DCM) and asynchrony. We measured basal asynchrony and early resynchronization by radionuclide angioscintigraphy (RNA) in order to predict long-term evolution of ventricular function after BiV. Thirty-four patients (NYHA Class III-IV,65.4 +/- 11 years) with large QRS(179 +/- 18 ms)were implanted with BiV and studied by RNA before (D0), at day 8 (D8), and during follow-up(20 +/- 7 months). We calculated left and right ejection fractions, the interventricular dyssynchrony (TRVLV), and the apicobasal dyssynchrony (Tab). LVEF improved from 20.2 +/- 8.1%(D0) to27.1%+/- 12.6%(follow-up,P < 0.003 vs D0) and RVEF from 28.6%+/- 13%(D0) to 34.3 +/- 11.5%(follow-up,P < 0.03 vs D0). Inter- (DeltaTRVLV) and intraventricular resynchronization was immediate and remained stable: TRVLV decreased from 68.3 +/- 38 ms(D0) to 13.4 +/- 48.5 ms(D8) and1.8 +/- 39.2 ms(follow-up,P < 0.0001 vs D0); and Tab from 45.8 +/- 64.1 msto-18 +/- 68(D8) and-28.3 +/- 53.6 ms(follow-up,P < 0.0001 vs D0). Early inter- and intraventricular resynchronization (DeltaTab) at D8 were related to late LVEF and RVEF improvement. Together, an LVEF > 15% and a significant interventricular dyssynchrony (TRVLV > 60 ms) at D0 have a sensitivity of 79% and a positive predictive value of 83% to predict an improvement of LVEF superior to 5% at follow-up. In DCM patients, BiV resynchronizes ventricles early and in the long-term, while RVEF and LVEF improve progressively. Patients with large electromechanical dyssynchrony benefit most from BiV.