Interpeak Intervals Research Articles

Beat-to-beat measurement of R-wave peak time for left bundle branch area pacing: man versus machine using a novel automated algorithm

Abstract Background Assessment of stimulation spike to R-wave peak time (RWPT) in V6 and in aVL, and V6-V1 interpreak interval, may be used to evaluate presence of conduction system capture during left bundle branch area pacing (LBBAP). This is performed by manual measurements which is tedious and requires a skilled operator to limit variability in the measurements. Automatic beat-to-beat measurement of these intervals may streamline workflow during implantation, but such an algorithm has never been tested so far. Purpose To test the feasibility of performing beat-to-beat automatic measurement of RWPT using an algorithm designed to measure the interval between the stimulation spike and the peak positive voltage, and to compare the results with manual measurements. Methods ECG recordings from 50 patients (28% female, mean age 81.5 ± 9.0 years) undergoing LBBAP implantation were evaluated on a electrophysiology recording system by manually measuring RWPT in V6 and in aVL and the V6-V1 interpeak intervals . A single operator performed offline measurements on 10 consecutive beats in each patient. The same beats were subjected to the same measurements using an automatic algorithm after signal conditioning in a novel EP recording System. The correlation between manual and automatic measurements was calculated. Variability of the measurements (evaluated by standard deviation) in the 10 consecutive beats was also compared. Results Of the 500 beats measured, 3 were excluded due to obvious morphological differences affecting the interval measurement (e.g. due to fusion beats). The algorithm was unable to make a measurement in V6 in 20 beats and manual assessment of aVL was not possible in one patient, meaning that 1461/1500 (97.4%) measurements were compared between the manual and automatic methods. The results are shown in the figure. There was excellent correlation between manual and automatic measurements, with lower variability using the latter method. Conclusion Beat-to-beat automatic measurement of RWPT is feasible and provides excellent correlation with manual measurements, with less variability in the values. This algorithm may streamline the measurements during implantation. However, prospective evaluation is required to confirm operation of the algorithm in the clinical setting to include challenges such as electrical noise.

Comparative study of the surface and endocavitary signals of cardiac pacing system analyzers with respect to the conventional polygraphy systems signals during implantation of conduction system pacing

Abstract Introduction and objectives Left bundle branch area pacing (LBBAP), is a novel modality of physiologic pacing that requires an adequate assessment of the endocardium as well as the body-surface electrocardiographic signals for a successful pacing-lead implantation. We aimed to assess if LBBAP criteria(1), specifically left ventricular septal pacing (LVSP) and left bundle branch pacing (LBBP) criteria, can be satisfactory measured using the signals resulting from different cardiac pacing analyzers (PSAs) by comparing them to the ‘conventional’ signals obtained from multichannel polygraph systems (MPSs) during the implantation procedure. Methods Comparative observational, prospective, multicenter study of consecutive patients who underwent a LBBAP strategy as first intention. LBBP was defined in the presence of a paced QRS with right bundle branch morphology in V1 (initial r wave in lead V1) and at least one of the following criteria: 1. V6-R-Wave Peak Time (RWPT) < 80 ms. 2. V1–V6 interpeak interval > 33 ms. 3. QRS transition from non-selective left bundle branch pacing to selective left bundle branch pacing or NS-LBBP to left ventricular septal pacing during pacing threshold. 4. Sudden increase of V6-RWPT > 15 ms because of reducing pacing output. 5. Left bundle potential-V6RWPT = stim-V6RWPT (±10 ms). For patients without initial r wave in V1, LBBP was considered in the presence of QRS transition during pacing. LVSP was defined by a paced QRS showing a typical terminal R-wave in V1, anatomical position of the lead in the left ventricular septum documented by fluoroscopy and not fulfilling the additional criteria previously described for LBBP. Results 63 patients were included. The basal characteristics of the patients are shown in Figure I. No significant differences (p<0.96) were observed in the basal QRS between the MPSs (129±29ms) and the PSAs (129±28ms). Initial "W" morphology in V1 during initial pacing was obtained in 90% of patients, without differences between both measurement systems. There were no significant differences between the MPSs and the PSAs in the paced QRS in V1 (140±10ms vs 141±12ms, p<0.746) nor in V6 (127.4±13ms vs 128.2±14.6ms, p<0.96). The measurement of the R wave peak time (RWPT) in V6 was 78.3±15ms vs 77±14 ms (p<0.72), and the V1-V6 inter-peak was 41.1±16ms in the MPSs vs 39±16 ms the PSAs (p<0.6), respectively, the Pearson correlation coefficients for these last two measurements being 0.91 (p <0.0001) and 0.91 (p <0.0001) (Figure II). Finally, according to electrocardiographic criteria measured by the MPSs, LBBP was achieved in 69% of patients, accomplishing 31% of the patients LVSP criteria, being the same proportions observed when PSAs measures where applied. Conclusions The signals resulting from the different PSAs can be useful to assess septal as well as LBBP criteria as an alternative to the ‘conventional’ signals obtained from MPSs.

Dual-chamber CRT-D using ICD lead implantation in the LBBAP position

Abstract Background Interest in conduction system pacing (CSP) has increased in recent years. For left bundle branch area pacing (LBBAP), 4F and 6F pacing leads have been shown to be effective and safe. No information is available on the potential use of ICD leads for LBBAP. Aim The objective of the study was to demonstrate the feasibility of implanting an ICD lead in the LBBAP position to reduce the number of leads for CRT-D therapy. Patients and Methods We implanted the 7F ICD lead in the LBBAP position through a new 10F CSP delivery sheath in ten consecutive patients. Periprocedural data, QRS morphology and degree of QRS reduction were analyzed. Results Ten consecutive patients (one female) aged 69.5±9.2 years were treated with the above-mentioned method. Eight patients had ischemic cardiomyopathy and two patients had nonischemic cardiomyopathy. All patients had a CRT-D indication. Eight patients had a wide QRS complex with complete LBB and a QRS complex of 184.8±25.8 ms. Two patients had a narrow QRS complex but first-degree AV block with a PR interval greater than 240 ms. Left ventricular ejection fraction was 31.8±8.6%. Operative and fluoroscopy times were 103.6±30.3 minutes and 10.5±6.1 minutes, respectively. On average, 1.7 ± 0.6 screwing attempts were required per patient. The intraprocedural LBBAP threshold was 0.78±0.6V/1.0ms, the impedance was 530.8±86.5 ohm, and the R-wave amplitude was 9±3.3mV. The unipolar paced QRS complex was 123.6±15.9ms, the bipolar paced QRS complex was 129.5±12.8ms, and the bipolar paced QRS complex on the next day was 133.3±11.7. The mean duration from stimulus to R-wave peak in lead V6 was 82.9 ± 19.7 ms. The R-wave interpeak interval between leads V6 and V1 was 43.4 ± 9.7 ms. All but one patient received an effective defibrillation threshold test at 30J (n=8) and 36J (n=1). One patient was not tested during the procedure due to high risk. Conclusion This first-in-human study of ICD lead implantation in the LBBAP position demonstrated its feasibility and efficacy in achieving conduction system stimulation. This approach may lead to a reduction in the number of leads implanted for cardiac resynchronization therapy. Figure 1. A- RAO view, angiography of the RV for verification of the TVA-summit. B- LAO view, angiography from the CSP- sheath after reaching final position of the LBBAP lead (right sided interventricular septum - yellow dotted line). C – 12 lead ECG (speed 50mm/sec) demonstrating paced and native QRS complexes. D – Fluoroscopy in RAO view, final result. E – Fluoroscopy in LAO view, final result. F – Transthoracic echocardiography the next day (4Ch view) demonstrates optimal LBBAP lead position.. RAO – right anterior oblique; LAO – left anterior oblique; TVA – tricuspid valve anulus; CSP – conduction system pacing; LBBAP – left bundle branch area pacing.Figure 1.

Left bundle fascicular versus left bundle trunk pacing: A comparison of their electrical synchrony parameters

BackgroundVariation in human left bundle branch (LBB) anatomy has a significant effect on the sequence of left ventricular depolarization. However, little is known regarding the electrophysiological characteristics of pacing different LBB fascicles. ObjectiveWe aimed to analyse the different electrocardiographic characteristics of LBB pacing (LBBP) attending to the site of pacing at the LBB system. MethodsIn 200 consecutive patients with confirmed LBBP, we distinguished left bundle trunk capture (LBTP) from any LB fascicular pacing (LBFP) based on the presence of LB potentials and paced QRS morphologies. We compared them regarding procedure, LBBP criteria and electrical synchrony parameters. ResultsOne hundred and seventy-three patients with LBFP were compared to 25 patients with LBTP. Left septal and posterior fascicles were significantly more prevalent than left anterior in LBFP (46.8 %, 41.0 % and 12.2 % respectively). QRS transition criteria (80.0 % vs 61.8 %; p = 0.077), selective LBBP (40.0 vs 21.5 %; p = 0.101), paced QRS width (110.3 ± 16.8 ms vs 115.4 ± 14.9 ms; p = 0.117), V6-RWPT (79.2 ± 10.7 ms vs 75.3 ± 9.7 ms; p = 0.068) and interpeak interval (42.5 ± 19.1 ms vs 45.7 ± 12.9 ms; p = 0.282) were not significantly different between LBTP and LBFP. All short-term complications occurred in LBFP, mainly driven by septal perforations (n = 23), without any difference in the pacing parameters. Among the LBFP subgroups, only aVL-RWPT was longer when the posterior fascicle was paced. ConclusionsLBFP is much more prevalent than LBTP in unselected consecutive patients with LBBP. LBFP seems more feasible, and as good as LBTP in terms of electrical synchrony and pacing safety.

Transcranial magnetic stimulation of primary motor cortex elicits an immediate transcranial evoked potential

BackgroundTranscranial evoked potentials (TEPs) measured via electroencephalography (EEG) are widely used to study the cortical responses to transcranial magnetic stimulation (TMS). Immediate transcranial evoked potentials (i-TEPs) have been obscured by pulse and muscular artifacts. Thus, the TEP peaks that are commonly reported have latencies that are too long to be caused by direct excitation of cortical neurons. MethodsIn 25 healthy individuals, we recorded i-TEPs evoked by a single biphasic TMS pulse targeting the primary motor hand area (M1HAND) or parietal or midline control sites. Sampling EEG at 50 kHz enabled us to reduce the duration of the TMS pulse artifact to a few milliseconds, while minor adjustments of the TMS coil tilt or position enabled us to avoid cranial muscular twitches during the experiment. ResultsWe observed an early positive EEG deflection starting after approx. 2 ms followed by a series of superimposed peaks with an inter-peak interval of ∼1.1–1.4 ms in multiple electrodes surrounding the stimulated sensorimotor region. This multi-peak i-TEP response was only evoked by TMS of the M1HAND region and was modified by changes in stimulation intensity and current direction. DiscussionSingle-pulse TMS of the M1HAND evokes an immediate local multi-peak response at the cortical site of stimulation. Our results suggest that the observed i-TEP patterns are genuine cortical responses evoked by TMS caused by synchronized excitation of pyramidal neurons in the targeted precentral cortex. This notion needs to be corroborated in future studies, including further investigations into the potential contribution of instrumental or physiological artifacts.

Left bundle branch area pacing in the setting of cardiac amyloidosis: a case series

Abstract Background Cardiac amyloidosis (CA) is a highly prevalent cause of congestive heart failure. It often requires cardiac pacing due atrioventricular conduction (AV) system disorders, often with cardiac resynchronization (CRT) to prevent development/deterioration of left ventricular (LV) dysfunction. Left bundle branch area pacing (LBBAP) is an emerging alternative to CRT, offering a strict physiological LV activation and very limited use of iodinated contrast. The feasibility of LBBAP in CA is considered limited due to the presence of septal pseudohypertrophy which theoretically limits left-sided conduction system engagement. Purpose To evaluate the feasibility and effectiveness of LBBAP in cardiac amyloidosis. Methods Consecutive patients with CA (both light-chain -AL- or wild-type transtiretin -wtATTr) with a pacing indication for AV conduction disorders were enrolled. Patients underwent baseline echocardiographic examination. LBBAP was achieved by means of stylet-driven leads advanced transeptally (right ventricle (RV) to LV) via dedicated delivery systems, with continuous monitoring of 12-lead electrocardiographic morphology and impedance until a typical QRS morphology in V1 was obtained (usually rSr’ or Sr’). Standard measures for left bundle (LB) capture were used (stimulus to peak R in V6 – S-RV6, V6-V1 interpeak interval, presence of transition in these measures during threshold testing, presence of fascicular signal during spontaneous QRS). Results Between January 2022 and June 2023, among 63 patients undergoing LBBAP, 7 patients (11%) had CA, 2 AL (28%) and 5 (72%) wtATTR. Patients were prevalently old (78±7 y) males (6, 85%); LV mean septal thickness was 17±2 mm (min 16, max 20 mm) and mean LV ejection fraction (LVEF) was 45±6%. Indications were PR prolongation in 3, bradycardic atrial fibrillation and LB branch block (LBBB) in 2, primary LBBB in 1 and chronic RV pacing in 1. Baseline QRS duration was 145±47 ms (QRS<120 ms: 97±15 ms, QRS>120 ms: 182±13 ms). LBBAP success was 100%. Fascicular electrograms were observed in ¾ of patients without LBBB; S-RV6 interval was 74 ±11 ms (³70 ms in 3), RV6-RV1 interpeak interval was 47±9 ms (³ 30 ms in 6 patients). DQRS in baseline broad QRS was -52 ms and +32 ms in narrow. No complications were observed. Over a short follow up of 6 months, an increase in average LVEF was observed (LVEF at 6 months: 51±3%, p<0.05). Conclusions In patients with CA, LBBAP is easily achievable with stylet-driven systems with frequent selective engagement of conduction system. QRS narrowing in baseline broad QRS is significant while QRS broadening in baseline narrow QRS is limited. Early results regarding follow-up of surrogate endpoint such as LVEF are promising.

Feasibility and safety of permanent left bundle branch area pacing in pediatric patients

Abstract Introduction Left bundle branch area pacing (LBBAP) is a promising pacing strategy with a low and stable pacing threshold. It maintains electrical and mechanical synchronization of the ventricles. Conduction system pacing (CSP) has evolved rapidly to become the pacing method of choice for many adult and pediatric patients. Recent studies have begun to demonstrate the feasibility and efficacy of CSP in pediatric patients. Nowadays, research articles about LBBAP in children are comparatively rare, therefore, research in this area is preferred. Limited data on LBBAP in pediatric patients (≤ 18 years old) are available. Purpose This study aims to describe the feasibility and safety of LBBAP in pediatric patients. Methods This study includes 4 patients: 1 male, and 3 females, respectively. The average age of the patients was 15.5±1.9 years and the weight was 51,5±17,6 kg. All patients were diagnosed with 3rd-degree atrioventricular (AV) block, in one case the total AV block occurred after previous radiofrequency ablation of the parahisian and right lateral accessory pathway. One patient had previously been implanted with an epicardial pacemaker and presented to our clinic with ventricular lead dysfunction. Pacing parameters were assessed during implantation, the next day after the procedure, and 1, 3 months follow-up. Echocardiography was performed to evaluate LV function and assess the approximate lead location and impact on tricuspid valve function. Results LBBAP was successfully achieved in all patients resulting in narrow QRS complexes (102±12.7ms) and right bundle branch block QRS morphology. To confirm left bundle branch area capture, peak left ventricular activation time (pLVAT) (84.5±4.1ms), V6-V1 (43.5±2.5ms) inter-peak interval, presence of left bundle potential, transition from non-selective to selective capture were recorded at during the implantation. The mean paced QRS duration was (108±13 ms). Pacing threshold and impedance remain stable (0.75±0.25V, and 615±50 Ohm, respectively). There was no major complication during the implanting process and follow-up. Conclusions LBBAP can be performed safely in children with narrow QRS complexes and can achieve stable pacing parameters.

Left bundle fascicular versus left bundle trunk pacing: a comparison of their electrical synchrony parameters

Abstract Background Variation in human left bundle branch (LBB) anatomy has a significant effect on the sequence of left ventricular depolarization. However, little is known regarding the electrophysiological characteristics of pacing different LBB fascicles. Objective We aimed to analyse the different electrocardiographic characteristics of LBB pacing (LBBP) attending to the site of pacing at the LBB system. Methods In consecutive patients with confirmed LBBP, we distinguished left bundle trunk capture (LBTP) from any LB fascicular pacing (LBFP) based on the presence of LB potentials and paced QRS morphologies in the frontal axis. We compared them regarding procedure, LBBP criteria and electrical synchrony parameters. Results 309 patients with LBBAP attempt were analysed, with 290 successful cases. Among them, 223 were considered LBBP. 25 cases without a proper ECG tracing in the frontal leads were excluded from the final analysis. 173 patients with LBFP were compared to 25 patients with LBTP. There were not significant differences in the baseline characteristics, but the native QRS width was higher in the LBFP group (119.2±31.4 ms vs 103.2±20.5 ms; p=0.014). Regarding the procedural duration, there was not any significant difference. QRS transition criteria (80.0% vs 61.8%; p=0.077), selective LBBP (40.0 vs 21.5%; p=0.101), paced QRS width (110.3±16.8 ms vs 115.4±14.9 ms; p=0.117), V6-RWPT (79.2±10.7 ms vs 75.3±9.7 ms; p=0.068) and interpeak interval (42.5±19.1 ms vs 45.7±12.9 ms; p=0.282) were not significantly different between LBTP and LBFP. All short-term complications occurred in LBFP, mainly driven by septal perforations (n=23), without any difference in the pacing parameters. Among the LBFP subgroups, left septal (LSFP) and posterior (LPFP) fascicles were significantly more prevalent than left anterior (LAFP) in LBFP (46.8%, 41.0% and 12.2% respectively). Regarding the baseline characteristics, the procedural performance and the electrical synchrony parameters, there were not significant differences among the LBFP subgroups. Only aVL-RWPT was longer when the posterior fascicle was paced, and shorter in LAFP (84.7±13.3 ms vs 64.9±15.1 ms; p<0.001). The consecution of LSFP was more frequent with lumenless leads (97.5% vs 83.1% vs 81.0%, p=0.006). Attending to the LBBP criteria, transition criteria were more frequent in LSFP (71.6% vs 53.2%; p=0.039), along with selective capture (29.6% vs 16.3%%; p=0.042), and transition during pacing manoeuvres (82.8% vs 69.2% vs 40.0%; p=0.013). Conclusions LBFP is much more prevalent than LBTP in unselected consecutive patients with LBBP. LBFP seems more feasible, and as good as LBTP in terms of electrical synchrony and pacing safety, without significant differences among the LBFP subgroups. The recognition of the different paced QRS morphologies in the frontal axis, along with the analysis of the Purkinje potentials, arise as important tools to fully understand the whole map of LBBAP.Left bundle branch area sites of pacingProcedural and LBBP characteristics

Efficacy and safety of lumenless leads compared with stylet-driven leads for left bundle branch area pacing

Abstract Introduction Left Bundle Branch Area Pacing (LBBAP) was initially performed with lumenless leads (LLLs). In the last years, stylet-driven leads (SDLs) have emerged as an alternative. However, we are still lacking data comparing these two different approaches. Purpose To compare the efficacy and safety of LLLs Vs SDLs for LBBAP. Methods 116 patients who underwent LBBAP attempt in our institution were prospectively included (mean age 74 ± 9 years, 40 (34%) female). We recorded and analyzed baseline characteristics, procedural findings, LBB capture criteria, lead parameters, success rates and complications. A 6-month remote follow-up data was programmed in every patient. Results We analyzed 75 patients who received LLLs and 41 patients with SDLs. Baseline characteristics were similar in both groups (table 1). There were no significant differences regarding Paced QRS (114 ± 18 ms Vs 117 ± 19 ms, p = 0.36), presence of a LB potential (16 (21%) Vs 9 (22%), p = 0.93), V6 R-wave peak time (V6RWPT) (83 ± 15 ms Vs 82 ± 16 ms, p = 0.71) or V6–V1 inter-peak interval (40 ± 17 ms Vs 37 ± 13 ms, p = 0.37). Time to lead implant was also similar (37 ± 18 minutes Vs 37 minutes ± 13 minutes, p = 0.87). Mean pacing voltage threshold was higher for SDLs after implantation (0.71 ± 0.33 V Vs 0.86 ± 0.30 V, p = 0.02) and also at the 6-month remote follow-up (0.75 ± 0.28 V Vs 0.9 ± 0.34 V, p = 0,04). R-wave amplitude and impedance were also higher in SDLs (table 1). According to 2023 EHRA clinical consensus statement on conduction system pacing, we achieved confirmed LBBP in 63 patients (54%), likely LBBP in 30 patients (26%) and Left Ventricular Septal Pacing (LVSP) in 21 patients (18 %), with no differences between groups (table 1). After the 6-month follow-up, a higher probability of lead dislodgement was appreciated in the SDLs group (3 (7%) Vs 0 (0%), p = 0,01). Conclusions LLLs and SDLs are effective tools to perform LBBAP, achieving similar paced QRS and and success rates. SDLs were associated with slightly higher pacing threshold. After the 6-month follow-up, a higher probability of lead dislodgement was appreciated in the SDLs group.

QRS transition during interrupted lead screwing-in to confirm left bundle branch capture during left bundle branch area pacing

Abstract Background QRS transition criteria during dynamic manoeuvers are the gold-standard for non-invasive confirmation of LBB capture, but they are seen in < 50% of LBBAP procedures. Purpose we hypothesized that transition from LVSP morphology to LBBP morphology, when observed during lead penetration into the deep IVS with interrupted pacemapping, can suggest LBB capture. Methods consecutive patients with an attempt of LBBAP procedure were selected at our institution. First, we defined QRS transition from LVSP to ns-LBBP capture during interrupted lead screwing-in pacemapping. Then, we compared LVSP and ns-LBBP morphologies, according to physiologic ECG-based criteria obtained in cases in which transition was demonstrated during dynamic ECG manoeuvres using differential output pacing, with LVSP and ns-LBBP morphologies obtained in cases in which transition was observed during lead screwing-in. QRS transition during lead screwing-in was defined as shortening of paced V6-RWPT by ≥10 ms from LVSP morphology to ns-LBBP morphology, obtained with interrupted pacemapping, during mid to deep septal lead progression at the same target area, between two consecutive pacing manoeuvres, deep and deeper, with a QR/rSR′ pattern in V1 in both (figure 1). Paced V6-RWPT had to remain short and constant in the deeper LBBP position, at high and low output pacing. Results 305 patients with attempted LBBAP were screened. Any transition in QRS morphology occurred in 139 out of 290 successful procedures (47.9%). In 17 patients both QRS transitions (ns-LBBP to s-LBBP and LVSP to ns-LBBP) were observed. The study population consisted of 104 patients with transition from LVSP to ns-LBBP: forty-four patients with transition during lead screwing-in were compared to 60 cases with a demonstrated transition criterion during pacing manoeuvres. Average shortening in paced V6-RWPT was similar among study groups (17.3±6.8 ms vs 18.8±4.9 ms for transition during dynamic manoeuvres and lead screwing-in, respectively; p=0.719). Paced V6-RWPT, paced aVL-RWPT, V6-V1 interpeak interval and the recently described LBBP score, were similar for ns-LBBP morphologies in both QRS transition groups (table 1). LVSP morphologies showed longer V6-RWPT and aVL-RWPT, shorter V6-V1 interpeak interval and lower LBBP score punctuation, when compared to ns-LBBP morphologies, but no differences among the two QRS transition groups appeared. Sixty one out of 104 ns-LBBP morphologies (58.7%) met the 100% specific criterion of V6-RWPT < 75 ms or V6-V1 interpeak interval > 44 ms, and it was more frequently achieved in ns-LBBP morphologies obtained during lead screwing-in compared to those obtained during dynamic manoeuvres (70.5% vs 50%, respectively p=0.036). Conclusions during LBBAP procedure, QRS transition from LVSP to ns-LBBP can be observed as the lead penetrates deep into the IVS with interrupted pacemapping. Shortening of at least 10 ms in paced V6-RWPT may serve as marker of LBB capture.Figure 1Table 1

Tailored electrocardiographic-based criteria for different pacing locations within the left bundle branch

Abstract Background QRS morphology transition criteria are the current gold-standard for the confirmation of LBB capture during LBBAP, but they are seen in less than 40% of procedures. Thus, physiologic ECG-based criteria are widely used to confirm LBBP. Current CSP guidelines recommend 100% specific cut-off points (V6-RWPT< 75 ms or V6-V1 interpeak interval > 44 ms) to confirm LBB capture but these values were never validated for different pacing locations. Purpose To describe diagnostic performance of paced V6-RWPT, V6-V1 interpeak interval and paced aVL-RWPT for different pacing sites within the LBB and to determine 100% specific values at each pacing location. Methods Consecutive patients with an attempt of LBBAP procedure were screened at our institution. Only patients with unequivocal LBB capture according to QRS transition criteria were selected. The study population was divided into subgroups according to the site of pacing (left bundle trunk pacing (LBTP), left septal fascicular pacing (LSFP), left posterior fascicular pacing (LPFP) and left anterior fascicular pacing (LAFP)). Results 147 patients with unequivocal LBB capture were analyzed (mean age 77.5±10.4 years, 50.3% male, 95.2% preserved LVEF, and 94.6% with bradycardia pacing indication. Non-diseased LBB (narrow QRS complex or isolated RBBB) was present in 70.7% of patients (n=104). Left fascicular pacing was the most common type of LBB capture achieved (82.8%) while LBTP accounted for 17.2% of cases. LFSP was the most frequent fascicular capture (54.1%), followed by LPFP (36%) and LAFP (9.9%). The ROC curves of paced V6-RWPT for the differential diagnosis of LBBP and LVSP showed good diagnostic performance among different pacing locations (figure 1). The highest AUC were found in patients with LSFP and LAFP (94.9% and 93.2%, respectively). The 100% V6-RWPT specific cut-off value was 68 ms (SN) 25%) in LPFP, 75 ms (SN 56.5%) in LBTP, 79.5 ms (SN 75%) in LSFP and 81 ms (SN 90.9%) in LAFP (figure 1). The diagnostic performance of V6-V1 interpeak interval was also good among study subgroups (figure 2). The highest AUC were found in patients with LBTP and LSFP (89% and 89.4%, respectively). The 100% V6-V1 interpeak interval specific cut-off value was 35.5 ms (SN 65.2%) in LBTP, 53.5 ms (SN 32.5%) in LPFP, 46 ms (SN 44.1%) in LSFP and 41 ms (SN 63.6%) in LAFP (figure 2). Diagnostic performance of paced aVL-RWPT was good among study subgroups (AUC of 93% in LAFP, 80.1% in LBTP, 84% in LSFP and 77.5% in LPFP). The 100% specific cut-off values for LBBP confirmation were 74 ms, 74.5 ms and 73.5 ms for LBTP, LSFP and LPFP patients, respectively, but it was 68 ms in patients with LAFP (SN 66.7%). Conclusions Diagnostic performance of the physiologic ECG-based criteria for the discrimination of LBBP, was good among different pacing locations within the LBB. Tailored cut-off values depending on the site of pacing might be useful additional tools for better LBB capture confirmation.Figure 1Figure 2

Auditory Effects of Acoustic Noise From 3-T Brain MRI in Neonates With Hearing Protection.

Neonates with immature auditory function (eg, weak/absent middle ear muscle reflex) could conceivably be vulnerable to noise-induced hearing loss; however, it is unclear if neonates show evidence of hearing loss following MRI acoustic noise exposure. To explore the auditory effects of MRI acoustic noise in neonates. Prospective. Two independent cohorts of neonates (N = 19 and N = 18; mean gestational-age, 38.75 ± 2.18 and 39.01 ± 1.83 weeks). T1-weighted three-dimensional gradient-echo sequence, T2-weighted fast spin-echo sequence, single-shot echo-planar imaging-based diffusion-tensor imaging, single-shot echo-planar imaging-based diffusion-kurtosis imaging and T2-weighted fluid-attenuated inversion recovery sequence at 3.0 T. All neonates wore ear protection during scan protocols lasted ~40 minutes. Equivalent sound pressure levels (SPLs) were measured for both cohorts. In cohort1, left- and right-ear auditory brainstem response (ABR) was measured before (baseline) and after (follow-up) MRI, included assessment of ABR threshold, wave I, III and V latencies and interpeak interval to determine the functional status of auditory nerve and brainstem. In cohort2, baseline and follow-up left- and right-ear distortion product otoacoustic emission (DPOAE) amplitudes were assessed at 1.2 to 7.0 kHz to determine cochlear function. Wilcoxon signed-rank or paired t-tests with Bonferroni's correction were used to compare the differences between baseline and follow-up ABR and DPOAE measures. Equivalent SPLs ranged from 103.5 to 113.6 dBA. No significant differences between baseline and follow-up were detected in left- or right-ear ABR measures (P > 0.999, Bonferroni corrected) in cohort1, or in DPOAE levels at 1.2 to 7.0 kHz in cohort2 (all P > 0.999 Bonferroni corrected except for left-ear levels at 3.5 and 7.0 kHz with corrected P = 0.138 and P = 0.533). A single 40-minute 3-T MRI with equivalent SPLs of 103.5-113.6 dBA did not result in significant transient disruption of auditory function, as measured by ABR and DPOAE, in neonates with adequate hearing protection. 2. Stage 5.

Optimum stimulus for eliciting masseter vestibular-evoked myogenic potential: a comparative exploration with three different acoustic stimuli

ObjectiveTo compare the EMG rectified amplitude, absolute latencies, interpeak interval, and Interaural asymmetry parameters of masseter vestibular-evoked myogenic potential (mVEMP) elicited using clicks, 500 Hz tone bursts, and 500 Hz NB CE-chirps.MethodTwenty-five young healthy adults in the age range of 18–27 years participated for the study. mVEMP was recorded using three different acoustic stimuli i.e., clicks, 500 Hz tone bursts, and 500 Hz NB CE-chirps. mVEMP was recorded at an intensity of 125 dB peSPL with 5.1/s repetition rate. The potentials were recorded ipsilaterally using zygomatic electrode montage and were filtered between 0.1 and 3000 Hz. EMG rectification of the responses was made prior to analysis.ResultsThe latencies of P1 and N1 were significantly earlier for chirps then followed by click and tone bursts. The EMG rectified amplitude was significantly larger for the potentials obtained using chirps followed by tone bursts and then the clicks. Masseter VEMP obtained using chirps had significantly larger interpeak interval than tone bursts and clicks. The mean amplitude asymmetry ratio was greater in the potentials obtained using chirps than the other two stimuli.ConclusionThe present study reveals that 500 Hz NB CE-chirps tend to produce mVEMP with larger response amplitude and earlier latencies and thus are considered better and constructive stimuli compared to clicks and tone bursts.

Beyond the waves: Unraveling pandemic outcomes with genomic insights and immunity analysis – Evidence from 14 countries

ObjectiveAlthough the World Health Organization and many governments have recategorized COVID-19 as a generally mild to moderately severe disease, consecutive pandemic waves driven by immune escape variants have underscored the need for timely and accurate prediction of the next outbreak. Nevertheless, little attention has been paid to translating genomic data and infection- and vaccine-induced immunity into direct estimates. MethodsWe retrieved epidemiologic and genomic data shortly before pandemic waves across 14 developed countries from late 2021 to mid-2022 and examined associations between early-stage variant competition, infection- and vaccine-induced immunity, and the time intervals between wave peaks. We applied regression analysis and the generalized estimating equation method to construct an inferential model. ResultsEach per cent increase in the proportion of a new variant was associated with a 1.0% reduction in interpeak intervals on average. Curvilinear associations between vaccine-induced immunity and outcome variables were observed, suggesting that reaching a critical vaccine distribution rate may decrease the caseload of the upcoming wave. ConclusionsBy leveraging readily accessible pre-outbreak genomic and epidemiologic data, our results not only substantiate the predictive potential of early variant fractions but also propose that immunity acquired through infection alone may not sufficiently mitigate transmission. Conversely, a rapid and widespread vaccination initiative appears to be correlated with a decrease in disease incidence.

Infants with neonatal Chronic Lung Disease are associated with delayed auditory conduction in the rostral brainstem after term

AimsVery Low Birthweight (VLBW) infants with neonatal Chronic Lung Disease (CLD) have been found to have functional impairment of the brainstem auditory pathway at term. This study investigated the functional status of the brainstem auditory pathway in VLBW infants with CLD after term for any abnormality. MethodsFifty-two VLBW infants were recruited at 50 weeks of Postconceptional Age: 25 with neonatal CLD and 27 without CLD. None had any other major complications to minimize confounding effects. Brainstem Auditory Evoked Responses were studied at 21‒91/s click rates. ResultsCompared with those without CLD, VLBW infants with CLD had relatively shorter latencies of BAER waves I and III, associated with a slightly lower BAER threshold. Wave V latency and I‒V interpeak interval did not differ significantly between the two groups of infants. The I‒III interval in infants with CLD was shorter than in those without CLD at 91/s clicks. However, the III‒V interval was significantly longer than in those without CLD at all click rates (all p < 0.05). There were no significant differences in the amplitudes of BAER wave components between the two groups of infants. ConclusionsThe main BAER abnormality in VLBW infants with CLD was a prolonged III‒V interval. Auditory conduction is delayed or impaired at more central regions of the brainstem in CLD infants. After term central auditory function is adversely affected by neonatal CLD. Monitoring post-term change is required to provide valuable information for post-term care of CLD infants.

Avaliação do processo maturacional auditivo em crianças portadoras da síndrome da infecção congênita pelo Zika vírus

ABSTRACT Purpose: to analyze the absolute latencies of waves I. III and V and the interpeak intervals I-III. III-V and I-V of the ABR recorded from different age groups of children with congenital zika virus infection and their peers without risk indicators for hearing impairment. Methods: 84 newborns and infants (N=51 study group and N=33 control group) divided into groups with different post-conceptual ages. with the results of their hearing exams analyzed by age group and compared with their peers without other risk indicators for hearing impairment. The assessment of the auditory pathway was conducted through tympanometry. otoacoustic emissions and auditory brain stem responses. Results: only the latency of wave I and the interpeak III-V showed no significant difference between the study and control groups. The absolute latency and interpeak values found in the study group were significantly lower than those found in the control group. Conclusion: the maturation of the brain stem in children with ZIKV infection occurred within normal limits. with no retrocochlear disorders until the age of 5 years.

The Effects of Stimulus Repetition Rate on Electrically Evoked Auditory Brainstem Potentials in Postlingually Deafened Adult Cochlear Implant Recipients.

Background: By using outcome prediction scores, it is possible to distinguish between good and poor performers with cochlear implants (CI) after CI implantation. The reasons for poor performance, despite good basic conditions, can be manifold. On the one hand, the postoperative fitting may be inadequate; on the other, neurophysiological disease processes may impair speech understanding with a CI. These disease processes are not yet fully understood. In acoustics, it is known that the auditory brainstem responses (ABR) and their latencies and amplitudes allow differential diagnosis based on reference values for normal-hearing individuals. The aim of this study was to provide reference values for electrically evoked brainstem responses (EABRs) in terms of rate-dependent latencies and amplitudes. Methods: 20 ears of 18 experienced adult CI recipients with a predicted and measured good postoperative word recognition score were recruited from the clinic's patient pool. In the same stimulation mode and intensity we measured latencies and interpeak-latencies of EABRs and electrically evoked compound action potentials (ECAPs). With a defined supra-threshold stimulation intensity above the individual ECAP threshold, we applied stimulation at several rates between 11 and 91 stimuli per second. Results: We found rate dependences for EABR latency t3 and t5 in the order of 0.19 ms and 0.37 ms, respectively, while ECAP was not affected by rate. Correspondingly, the interpeak intervals' rate dependences for t5-t1, t5-t3 and t3-t1 were of the order of 0.37 ms, 0.18 ms and 0.19 ms. Comparing the EABR amplitudes between the stimulation rates 11/s and 81/s, we found that at 81/s the amplitudes were significantly reduced down: to 73% for A3 and 81% for A5. These rate dependences of latency and amplitude in EABR have characteristics comparable to those of acoustic ABR. Conclusions: These data may serve to provide reference values for EABR and ECAP latencies, interpeak intervals and amplitudes with respect to stimulation rate. Altered response patterns of ECAPs and EABRs to normalised stimulation modes could be used in the future to describe and classify neuropathological processes in a better-differentiated way.

Magnetic resonance spectroscopy and auditory brain-stem response audiometry as predictors of bilirubin-induced neurologic dysfunction in full-term jaundiced neonates

The purpose of this research was to define the functions of MRS and ABR as predictors of bilirubin-induced neurologic dysfunction (BIND) in full-term neonates who required intervention (phototherapy and/or exchange transfusion). This prospective cohort study was done at the NICU of Tanta University Hospitals over a 2-year duration. Fifty-six full-term neonates with pathological unconjugated hyperbilirubinemia were divided according to MRS and ABR findings into 2 groups: group (1) included 26 cases with mild acute bilirubin encephalopathy (BIND-M score 1–4). Group (2) included 30 cases with neonatal hyperbilirubinemia only. In addition, 20 healthy neonates with similar ages were employed as the controls. When compared to group 2 and the control group, group 1’s peak-area ratios of NAA/Cr and NAA/Cho were found to be significantly reduced (P < 0.05). As compared to group 2 and the control group, group 1’s Lac/Cr ratio was significantly greater (P < 0.05), but the differences were not significant for group 2 when compared to the control group. Waves III and V peak latencies, I–III, and I–V interpeak intervals were significantly prolonged in group 1 in comparison to group 2 and controls (P < 0.05) with no significant difference between group 2 and control group. Conclusion: When the symptoms of ABE are mild and MRI does not show any evident abnormalities, MRS and ABR are helpful in differentiating individuals with ABE from patients with neonatal hyperbilirubinemia. Trial registration: ClinicalTrials.gov, Identifier: NCT06018012.What is Known:• MRS can be used as a diagnostic and prognostic tool for the differential diagnosis of patients with acute bilirubin encephalopathy, from patients with neonatal hyperbilirubinemiaWhat is New:• ABR is a useful diagnostic and prognostic tool in the care and management of neonates with significantly raised bilirubin. It can be used as early predictor of acute bilirubin encephalopathy in the earliest stage of auditory damage caused by bilirubin.

Suboptimal postnatal function of brainstem auditory pathway in late preterm infants who do not have major perinatal and postnatal complications

ObjectivesTo examine postnatal functional status of the brainstem auditory pathway in late preterm infants and detect any postnatal auditory abnormality. MethodsThirty preterm infants born at 33–36 weeks gestation were studied three months after term. None had major perinatal and postnatal complications to minimize confounding effects. Brainstem auditory evoked responses were recorded with 21–91/s clicks. ResultsCompared with postnatal age-matched normal term infants, the late preterm infants did not manifest any major abnormalities in brainstem auditory evoked responses at conventionally used 21/s clicks. At higher click rates, however, the late preterm infants manifested a moderate prolongation in BAER wave V latency. All interpeak intervals tended to be prolonged at higher click rates. The I-V interval was significantly prolonged at 51/s and particularly at 91/s clicks. Both the I-III and III-V intervals were significantly prolonged at 91/s. The late preterm infants also manifested reduced amplitudes of BAER waves III and V at most click rates. ConclusionThe central components of the brainstem auditory evoked responses were abnormal at higher click rates three months after term in the late preterm infants. Postnatal brainstem auditory function is suboptimal in late preterm infants without major complications. This suboptimal brainstem auditory function may not be clearly shown at term or an earlier stage, but can be shown later. Late preterm infants, although they may not have major complications, should be followed for later auditory development, providing valuable information for improving postnatal care.

Abstract 16153: Electrocardiographic Correlations With Cardiac Magnetic Resonance in Left Bundle Branch Area Pacing

Introduction: As the use of left bundle branch area pacing (LBBAP) continues to increase, there remains uncertainty about the mechanical effects of achieving selective LBB capture. Hypothesis: The hypothesis was that cardiac magnetic resonance (CMR) strain and functional parameters would be similar with and without LBBAP, and mechanical function would be more favorable with surface ECG parameters indicative of LBB capture. Methods: CMR was performed at 3T in two centers in the first year after implantation of dual-chamber pacemakers with LBBAP. Imaging sets were obtained with dual-chamber LBBAP (DOO mode) and, in patients with intact atrioventricular (A-V) conduction, atrial-only pacing (AOO mode), including strain imaging with displacement encoding with stimulated echoes (DENSE). Results: In 17 patients, the median LVEF with LBBAP was 50% (IQR 48-52%). The median LVEF and RVEF were similar with LBBAP on (DOO mode) and off (AOO mode) (p=0.27 and p=0.37, respectively); however, there were differences in synchrony (CURE-SVD) (p=0.0081), mean septal Ecc (p=0.011), and mean LV free wall Ecc (p=0.011) that favored atrial-only pacing with A-V conduction vs. sequential LBBAP (Figure 1). A shorter interval between R wave peaks in ECG leads V6 and V1 (V6-V1 interpeak interval), shown to be associated with selective LBB capture, was the best predictor of a greater LVEF with LBBAP (p=0.0016). A shorter paced QRS duration predicted greater global Ecc (p=0.044) and more synchrony by the CURE-SVD (p=0.027) (Figure 2). Conclusions: LBBAP reproduces biventricular function by CMR with some differences noted in CMR strain, and selective LBB capture was associated with a greater LVEF by CMR.