Heart rhythm最新文献

Background: The leadless Micra AV pacemaker is designed to provide atrioventricular (AV) synchronous tracking by detecting atrial contraction. Detection of the mechanical atrial signals can become challenging at a fast sinus rate.

Objective: The purpose of the study was to evaluate the AV synchronous performance at exercise in outpatients implanted with a Micra AV pacemaker.

Methods: Patients were enrolled at least 1 month after Micra AV implantation and underwent a cycle test protocol. Serial device interrogations (each minute) and continuous electrocardiograms were collected to measure AV synchrony and determine maximum achieved sinus and ventricular rates for each patient. In addition, the A1, A2, A3, and A4 accelerometer signal amplitudes were measured at the start and peak of exercise.

Results: Thirty-five patients (mean age 75.6 ± 13.4 years; 80% male) were enrolled in the study; 22 (64%) were predominantly ventricular paced (>90%) during exercise. Average AV synchrony was 90.4% in the entire cohort and 84.7% in patients with high-degree AV block. The mean amplitude of the accelerometer signals increased significantly from the start to the peak of exercise: A1, 4.1-6.3 m/s²; A2, 2.4-3.8 m/s²; and A4, 4.5-7.6 m/s² (P < .01 for all). The time from the VP-A2 decreased 25 ms for each 100 ms of the R-R interval decrease.

Conclusion: Maintaining AV synchrony during maximal exercise in elderly patients is achievable by adequate detection of atrial contraction at high sinus rates by the leadless Micra AV pacemaker. All components of the accelerometer signal increased, likely because of increased contractility related to exercise.

Atrial fibrillation (AF), the most common arrhythmia in the United States, affects 6 million Americans, with numbers projected to increase to 12 million by 2030. A racial paradox difference in the incidence and prevalence of AF exists between Black and White Americans. Black Americans are less prone than White Americans to development of AF, but they display a higher burden of modifiable risk factors for cardiovascular disease and higher rates of ischemic stroke. Data pertaining to the American Heart Association Life's Simple 7 (LS7) health metrics show that Black Americans have suboptimal LS7 scores compared with White Americans on average despite lower genetic predisposition to AF. This trend suggests the impact of cardiovascular health on the development and progression of AF. Social, genetic, and lifestyle risk factors have been shown to play a role in the racial paradox and AF outcomes in Black Americans. This review summarizes factors contributing to the racial paradox and discusses suggestions for improved health outcomes in Black Americans with AF.

Background: Twin atrioventricular (AV) nodes (TWAVNs) are common in heterotaxy syndrome.

Objective: The purpose of this study was to investigate the presence and implications of TWAVNs and accessory pathways in congenital heart diseases (CHDs) with abnormal AV connections.

Methods: A retrospective study of a 1980-2022 cohort with sufficient electrocardiographic (ECG) data for review was conducted.

Results: We enrolled 136 patients with heterotaxy syndrome, 70 with congenitally corrected transposition of the great arteries (ccTGA) (4 with Ebstein anomaly), 47 with double-inlet ventricle (DIV), and 63 with isolated AV canal defect. TWAVNs, detected in the same ECG (18%), in separate ECGs (70.8%), or after electrophysiological study (11.2%), were present in 43.4% of heterotaxy, 10.6% of DIV, 10% of ccTGA, and 1.6% of AV canal defect cases. Accessory pathways were noted in 11.4% of ccTGA and 4.4% of heterotaxy cases, but none of the DIV and AV canal cases. Actuarial incidence of supraventricular tachycardia (SVT) by age 10 was 0.354, 0.121, 0.022, and 0 in heterotaxy, ccTGA, DIV, and AV canal, respectively. In patients with TWAVNs, the risk of SVT varies according to the rate of TWAVNs in each CHD type, with risks of 65.5%, 58.3%, and 0% for TWAVNs rates >50%, 10%-50%, and <10%, respectively. Onset age of tachycardia did not differ between those with TWAVNs and those with accessory pathways.

Conclusion: In CHD with abnormal AV connections, evidence suggested a developmental hierarchy in the propensity to exhibit TWAVNs, but not for accessory pathways. The earlier cardiac developmental errors occur, the higher the likelihood of TWAVNs and the greater the chance of SVT.

Background: Pregnancy is associated with greater vulnerability to supraventricular tachyarrhythmias.

Objective: As the underlying mechanisms remain to be elucidated, we investigated whether pregnancy induces atrial remodeling that might contribute to this.

Methods: Atrial electrophysiological and contractile properties were examined in nonpregnant and pregnant (P) mice. Cell shortening and Ca²⁺ imaging were measured on atrial myocytes. Atrial action potential and ionic currents were recorded using the patch-clamp technique. Atrial messenger RNA and protein expression were analyzed using qPCR and Western blot.

Results: The P-wave area on the electrocardiogram increased by 50% during pregnancy, suggesting atrial enlargement, confirmed by echocardiography. The atrial myocytes were longer in P mice, adding further evidence to the physiological hypertrophy associated with pregnancy. Echocardiography showed a 50% increase in atrial fractional area change during pregnancy, indicating much stronger contraction. A similar increase in cell shortening was observed in P mice and was associated with a decrease in sarcomere length and changes in myofilament protein phosphorylation. However, pregnancy did not affect L-type Ca²⁺ current, Ca²⁺ transients, and SR Ca²⁺ load. Myocytes from P mice showed twice as many spontaneous contractions and spontaneous diastolic Ca²⁺ releases. Moreover, pregnancy was associated with a 50% increase in action potential duration, linked to a reduction in the density of the Ca²⁺-independent transient outward K⁺ current and the underlying K_V4.3 channel.

Conclusion: During pregnancy, atrial tissues undergo substantial remodeling, potentially contributing to the development of supraventricular tachyarrhythmias.

Background: Patients with repaired Tetralogy of Fallot (rTOF) are at risk of ventricular tachycardia (VT) and sudden cardiac death (SCD). Most VTs arise from 5 slowly conducting isthmuses (SCAI; conduction velocity ≤ 0.5 m/s) bound by the right ventriculotomy, ventricular septal defect patch, tricuspid and pulmonic valves. Historically, risk stratification electrophysiology studies (EPS) involved programmed ventricular stimulation (PVS) with VT induction guiding ICD implantation and/or VT ablation.

Objective: To evaluate a "prophylactic" strategy of ablating SCAI even in the absence of inducible VT to reduce ICD implantation and arrhythmic events, and to compare this to the "historical" strategy.

Methods: This was a single-center, retrospective cohort study. The "historical cohort" underwent PVS to guide ICD implantation and/or VT ablation. The "prophylactic cohort" underwent right ventricular electroanatomic mapping and ablation of SCAI. A composite endpoint of arrhythmic death, cardiac arrest, sustained VT, and ICD complication was compared between the cohorts.

Results: Ninety-three patients with rTOF had risk stratification EPS. Of 57 prophylactic patients, SCAI were identified/ablated in 33 (58%), 16 (28%) had inducible VT before ablation, and 1 received ICD. Of 35 historical patients, 15 (43%) had inducible VT: 3 had cryoablation during PVR and 11 received ICD. No prophylactic patients met the composite endpoint over median 21 months (IQR 8,35) versus 10 (29%) historical patients over median 125 months (IQR 90,142; p= 0.017). There were no ablation-related complications.

Conclusion: Prophylactic SCAI ablation is associated with fewer ICD implants and a reduction in incident arrhythmic events without ablation-related complications.

Background: The interrupted technique of left bundle branch pacing (LBBP) limits the continuous monitoring of paced electrocardiogram and intracardiac electrogram (EGM) transitions, which may result in overlooked or misinterpreted subtle transitions.

Objectives: This study aimed to explore the electrophysiological characteristics of lead position-dependent EGM continuous transitions to evaluate lead depth and to investigate the clinical significance of transseptal pacing modalities.

Methods: A continuous pacing and recording technique enabled by a rotatable connector was used to allow the real-time monitoring of progressive changes in paced EGM and electrocardiographic morphology. Careful observations were conducted to evaluate whether there were significant changes in the amplitude and morphology of the ventricular current of injury (COI), R-wave peak times in leads V₁ and V₆, QRS duration, and impedance at different interventricular septal depths.

Results: The study included 105 patients. Nonselective LBBP was achieved in 94 patients (89.5%), of whom 88 (83.8%) achieved selective LBBP (SLBBP). Left ventricular septal pacing was confirmed in 11 patients (11.5%). The amplitude of ventricular EGM predictably changed with radial septum depth and peaked in the interventricular septum (26.3±11.3 mV). As the lead was inserted into the left ventricular subendocardium, the ventricular COI declined to a level approximating that of the right septum (11.7 ± 6.3 mV for SLBBP vs 10.4 ± 5.8 mV for right ventricular septal pacing). When selective left bundle branch capture occurred, significant morphological transitions in the ventricular COI were observed in the unfiltered EGM.

Conclusion: The continuous recording technique provides a more detailed understanding of pacing lead radial depth throughout implantation. COI amplitude and morphology variations can identify different pacing modalities, particularly in recognizing SLBBP.

Background: Different iterations of catheter and energy delivery system configurations are evolving for pulsed field ablation (PFA); however, some have used large and complex catheters, required large sheaths and had a recognised risk of haemolysis.

Objective: To evaluate the acute safety and efficacy of a custom designed 8F variable loop multielectrode mapping and PFA catheter with contact sensing.

Methods: This acute feasibility study recruited 30 patients undergoing de novo ablation of paroxysmal or persistent atrial fibrillation (AF). The ElectroPulse Study is a first-in-human, non-randomised, prospective study of a novel PFA system that utilizes an 8F 10-electrode variable loop steerable mapping and ablation catheter with 2800V biphasic bipolar waveform. All patients had pulmonary vein (PV) and posterior wall isolation (PWI) using the PFA system. The main outcomes were the acute success of PV/PWI and peri-procedural serious adverse events.

Results: Complete PV/PWI was successfully achieved in all 30 patients with 59.7±7.2 applications. Total procedural time was 113.6±26.3 mins with fluoroscopy time of 8.0±5.5 mins and LA dwell time of 78.7±18.6 mins. There was no esophageal injury, phrenic nerve palsy, clinical stroke or death. Brain MRI detected 2 new but transient silent cerebral lesions. Two patients (6.7%) had vascular access complications. Although there were changes in the biomarkers for hemolysis, none of the patient experienced clinical hemolysis or related acute kidney injury.

Conclusion: This first-in-human study demonstrated that PFA using a novel variable loop catheter with a contact sensing system safely achieved 100% acute PVI/PWI with safety profile comparable to existing PFA systems.