Feasibility of carbon dioxide insufflation and impact on epicardial approach utilization for ventricular tachycardia ablation in a midvolume referral center.

BACKGROUND: Epicardial access is often crucial for successful ventricular tachycardia (VT) ablation, but it is often burdened by significant procedural risk. Intentional coronary vein exit and intrapericardial CO2 insufflation (EpiCO2) can facilitate subxiphoid pericardial access. OBJECTIVE: This prospective study aimed to assess procedural feasibility, safety, and impact of the introduction of intrapericardial CO2 insufflation for epicardial access in a referral center for VT ablation. METHODS: All consecutive patients treated with epicardial VT ablation between November 2022 and January 2024 with the EpiCO2 technique at Pisa University Hospital were prospectively enrolled and compared in terms of feasibility, efficiency, and safety with a local retrospective cohort of patients treated with subxiphoid dry puncture between July 2018 and October 2022. RESULTS: Twenty-two consecutive patients (90.9% male; mean age, 54.3 years) underwent VT ablation with EpiCO2 during the study period. Epicardial access was achieved in all patients; median time from coronary sinus (CS) cannulation to epicardial access was 33 minutes. Intentional vein exit was successful in all cases, whereas CO2 insufflation was not feasible in 1 patient. There were no major complications and no significant bleeding. Since EpiCO2 introduction, epicardial approach utilization increased from 17.8% to 40% of all VT procedures. Comparison with 20 standard dry approach epicardial ablations showed no significant differences in terms of total procedural duration (322.5 [interquartile range, 296.75-363.75] minutes vs 359 [interquartile range, 323-409] minutes; P = .08). CONCLUSION: In our single-center experience, EpiCO2 was feasible and safe and led to significant increase in procedural volume without affecting total procedural time compared with standard dry puncture.

Transvenous lead extraction: Efficacy and safety of the procedure in female patients.

Background: Existing data on the impact of sex differences on transvenous lead extraction (TLE) outcomes in cardiac device patients are limited. Objective: The purpose of this study was to evaluate the safety and efficacy of mechanical TLE in female patients. Methods: A retrospective evaluation was performed on 3051 TLE patients (group 1: female; group 2: male) from a single tertiary referral center. All individuals received treatment using single sheath mechanical dilation and various venous approaches as required. Results: Our analysis included 3051 patients (group 1: 750; group 2: 2301), with a total of 5515 leads handled with removal. Female patients were younger, had a higher left ventricular ejection fraction, and lower prevalences of coronary artery disease and diabetes mellitus. Infection was more common in male patients, whereas lead malfunction or abandonment were more frequent in female patients. Radiologic success was lower in female patients (95.8% vs 97.5%; P = .003), but there was no significant difference in clinical success between groups (97.2% vs 97.5%; P = .872). However, major complications (1.33% vs 0.60%; P <.001) and procedural mortality (0.4% vs 0.1%; P <.001) were higher in females compared to male patients. After multivariate analysis, female sex emerged as the only predictor of major complications, including deaths (odds ratio 3.96; 95% confidence interval 1.39-11.24). Conclusion: TLE using unpowered simple mechanical sheaths in female patients is safe and effective, but is associated with lower radiologic success and higher complication rates and mortality than in males. This finding underscores the importance of recognizing sex differences in TLE outcomes.

Short and Long-Term Outcomes of Lesion Index-Guided High-Power Short-Duration Approach for Atrial Fibrillation Ablation.

High-power short-duration (HPSD) ablation is an increasingly used ablation strategy for pulmonary vein isolation (PVI) procedures, but Lesion Index (LSI)-guided HPSD radiofrequency (RF) applications have not been described in this clinical setting. We evaluated the procedural efficiency and safety of an LSI-guided HPSD strategy for atrial fibrillation (AF) ablation. Paroxysmal and persistent AF patients scheduled for AF ablation were prospectively enrolled and divided into two groups, according to the ablation power used (≥45 W for the LSI-HP Group and ≤40 W for the LSI-LP group). All patients underwent only PVI LSI-guided ablation (5.5 to 6 anteriorly; 5 to 5.5 superiorly, 4.5 to 5 posteriorly) with a point-by-point strategy and an inter-lesion distance <6 mm. Forty-six patients with AF (25 in the LSI-HP Group vs 21 in the LSI-LP Group)-59% paroxysmal, 78% male, with low-intermediate CHA2DS2-Vasc scores (2 [1-3]), a preserved ejection fraction (65 ± 6%) and a mean left atrial index volume of 39 ± 13 mL/m2 were prospectively enrolled. Baseline clinical characteristics were comparable between groups. PVI was successful in all patients. The RF time (29 (23-37) vs. 49 (41-53) min, p < 0.001), total procedure time (131 (126-145) vs. 155 (139-203) min, p = 0.007) and fluoroscopy time (12 (10-18) vs. 21 (16-26) min, p = 0.001) were significantly lower in the LSI-HP Group. No complications or steam pops were seen in either group. LSI-HP AF ablation significantly improved procedural efficiency-reducing ablation time, total procedural duration, and fluoroscopy use, while maintaining a comparable safety profile to lower-power procedures.

Feasibility and Accuracy of Noninvasive Continuous Arterial Pressure Monitoring during Transcatheter Atrial Fibrillation Ablation.

INTRODUCTION: Transcatheter atrial fibrillation (AF) ablation is still carried out with continuous invasive radial arterial blood pressure (IBP) monitoring in many centers. Continuous noninvasive blood pressure (CNBP) measurement using the volume-clamp method is a noninvasive alternative method used in ICU. No data on CNBP reliability are available in the electrophysiology lab during AF ablation, where rhythm variations are common. BACKGROUND: The objective of the present study was to compare continuous noninvasive arterial pressure measured with the ClearSight device (Edwards Lifesciences, Irvine, CA, USA) with invasive radial artery pressure used as the reference method during AF ablation. METHODS: We prospectively enrolled 55 consecutive patients (age 62 ± 11 years, 80% male) undergoing transcatheter AF ablation (62% paroxysmal, 38% persistent) at our center. Standard of care IBP monitoring via a radial cannula and a contralateral noninvasive finger volume-clamp CNBP measurement device were positioned simultaneously in all patients for the entire procedure. Bland-Altman analysis was used to analyze the agreement between the two techniques. RESULTS: A total of 1219 paired measurements for systolic, diastolic, and mean arterial pressure were obtained in 55 subjects, with a mean (SD) of 22 (9) measurements per patient. The mean bias (SD) was -12.97 (13.89) mmHg for systolic pressure (level of agreement -14.24-40.20; correlation coefficient 0.84), -1.85 (8.52) mmHg for diastolic pressure (level of agreement -18.54-14.84; correlation coefficient 0.77) and 2.31 (8.75) mmHg for mean pressure (level of agreement -14.84-19.46; correlation coefficient 0.85). CONCLUSION: In patients undergoing AF ablation, CNBP monitoring with the ClearSight device showed acceptable agreement with IBP monitoring. Larger studies are needed to confirm the potential clinical implications of continuous noninvasive BP monitoring during AF ablation.

Myocardial Inflammation, Sports Practice, and Sudden Cardiac Death: 2021 Update.

Myocardial inflammation is an important cause of cardiovascular morbidity and sudden cardiac death in athletes. The relationship between sports practice and myocardial inflammation is complex, and recent data from studies concerning cardiac magnetic resonance imaging and endomyocardial biopsy have substantially added to our understanding of the challenges encountered in the comprehensive care of athletes with myocarditis or inflammatory cardiomyopathy (ICM). In this review, we provide an overview of the current knowledge on the epidemiology, pathophysiology, diagnosis, and treatment of myocarditis, ICM, and myopericarditis/perimyocarditis in athletes, with a special emphasis on arrhythmias, patient-tailored therapies, and sports eligibility issues.

Sports Activity and Arrhythmic Risk in Cardiomyopathies and Channelopathies: A Critical Review of European Guidelines on Sports Cardiology in Patients with Cardiovascular Diseases.

The prediction and prevention of sudden cardiac death is the philosopher's stone of clinical cardiac electrophysiology. Sports can act as triggers of fatal arrhythmias and therefore it is essential to promptly frame the athlete at risk and to carefully evaluate the suitability for both competitive and recreational sports activity. A history of syncope or palpitations, the presence of premature ventricular complexes or more complex arrhythmias, a reduced left ventricular systolic function, or the presence of known or familiar heart disease should prompt a thorough evaluation with second level examinations. In this regard, cardiac magnetic resonance and electrophysiological study play important roles in the diagnostic work-up. The role of genetics is increasing both in cardiomyopathies and in channelopathies, and a careful evaluation must be focused on genotype positive/phenotype negative subjects. In addition to being a trigger for fatal arrhythmias in certain cardiomyopathies, sports also play a role in the progression of the disease itself, especially in the case arrhythmogenic right ventricular cardiomyopathy. In this paper, we review the latest European guidelines on sport cardiology in patients with cardiovascular diseases, focusing on arrhythmic risk stratification and the management of cardiomyopathies and channelopathies.

Recent advances in three-dimensional electroanatomical mapping guidance for the ablation of complex atrial and ventricular arrhythmias.

PURPOSE: To provide a brief overview of some relevant technological advances in the field of three-dimensional electroanatomical mapping (3D-EAM) that have recently entered the clinical arena and their role in guiding catheter ablation (CA) of complex atrial and ventricular arrhythmias. METHODS: In this technical report, we describe the general features of three novel algorithms featured in the updated CARTO PRIME™ mapping module for CARTO®3 version 7 3D-EAM system (Biosense Webster Inc., Diamond Bar, CA, USA): local activation time (LAT) hybrid, coherent mapping and map replay modules. We also report three challenging arrhythmia cases in which CA was successfully guided by these softwares. RESULTS: The LAT hybrid module was used in a case of premature ventricular complex originating from the right coronary cusp. This algorithm facilitated safe positioning of the ablation catheter away from the right coronary ostium, avoiding potential harm to this vital structure. The coherent mapping module helped to identify the critical as well as a bystander isthmus of an atrial macro-re-entrant tachycardia in a grown-up patient with congenital heart disease. The map replay module allowed rapid retrospective activation mapping of two unstable ventricular tachycardias in a case of nonischemic cocaine-associated cardiomyopathy. CONCLUSION: 3D-EAM systems offer significant advantages in the management of challenging arrhythmias, and the introduction of novel algorithms underpins improvements in patients' outcomes. Given the increasing sophistication of these systems, however, a close collaboration among cardiac electrophysiologists, engineers and technicians is highly needed in order to get the best from the available technology.

Voltage gradient mapping and electrophysiologically guided cryoablation in children with AVNRT.

Aims: Recently, voltage gradient mapping of Koch's triangle to find low-voltage connections, or 'voltage bridges', corresponding to the anatomic position of the slow pathway, has been introduced as a method to ablate atrioventricular nodal reentry tachycardia (AVNRT) in children. Thus, we aimed to assess the effectiveness of voltage mapping of Koch's triangle, combined with the search for the slow potential signal in 'low-voltage bridges', to guide cryoablation of AVNRT in children. Methods and results: From June 2015 to May 2016, 35 consecutive paediatric patients (mean age 12.1 ± 4.5 years) underwent 3D-guided cryoablation of AVNRT at our Institution. Fifteen children were enrolled as control group (mean age 14 ± 4 years). A voltage gradient mapping of Koch's triangle was obtained in all patients, showing low-voltage connections in all children with AVNRT but not in controls. Prior to performing cryoablation, we looked for the typical 'hump and spike' electrogram, generally considered to be representative of slow pathway potential within a low-voltage bridge. In all patients the 'hump and spike' electrogram was found inside bridges of low voltage. Focal or high-density linear lesions, extended or not, were delivered guided by low-voltage bridge visualization. Acute success rate was 100%, and no recurrence was reported at a mean follow-up of 8 ± 3 months. Conclusions: Voltage gradient mapping of Koch's triangle, combined with the search for the slow potential signal in low-voltage bridges, is effective in guiding cryoablation of AVNRT in paediatric patients, with a complete acute success rate and no AVNRT recurrences at mid-term follow-up.

Radiofrequency catheter ablation of left-sided accessory pathways in children using a new fluoroscopy integrated 3D-mapping system.

Introduction: Advances in 3D electroanatomic-mapping technologies have resulted in a safe and effective profile of radiofrequency (RF) catheter ablation. The aim of this study was to evaluate a different catheter ablation approach in patients with left-sided accessory pathways (APs). Methods and results: From January 2015 to December 2015, 30 patients (median age 11 years, median weight 45 kg) with manifest or concealed left-sided APs underwent RF catheter ablation with a new protocol. All procedures were performed with the CARTO UNIVU™ system, integrating electroanatomic maps with fluoroscopic views. A 7 Fr ablation catheter was inserted into the right femoral vein and advanced into the right atrium. Geometrical reconstruction and activation map of the right atrium, tricuspid annulus, and coronary sinus were acquired. The ablation catheter was then inserted into the left femoral artery and advanced through the aorta and aortic valve, creating an activation map of the mitral annulus. Catheter ablation was targeted to the site of the earliest activation. No complications occurred. The median procedure and fluoroscopy times were 130 min and 6 s, with a median fluoroscopy dose 0.5 mGy. An average of two catheters was used. Long-term success rate was 97% (29/30) at a median follow-up of 9.6 months. This approach reduced fluoroscopy time, dose and number of catheters used compared with manifest or concealed left-sided AP ablation using CARTO 3™ (P < 0.05). Conclusions: This new ablation protocol seems to be promising in reducing fluoroscopy exposure and number of catheters used during left-sided AP ablation in children.

Impact of haemodynamic SonR sensor on monitoring of left ventricular function in patients undergoing cardiac resynchronization therapy.

AIMS: The haemodynamic SonR sensor is able to measure myocardial contractility. The isometric effort is useful in quantifying left ventricular (LV) performance. We investigated the amplitude changes in SonR signal over time and during static exercise according to the recovery of the left ventricle. METHODS AND RESULTS: Twenty five patients [18 male, 70 ± 8 years, LV ejection fraction (LVEF) 29 ± 5%, in sinus rhythm] underwent biventricular SonR implantable cardioverter defibrillator implant. After procedure and at 6 months, each patient underwent detection of SonR signal and continuous measurement of blood pressure, at rest and during isometric effort. During evaluation at baseline device was programmed in VVI at 40 bpm while in DDD at 60 bpm at follow-up. At 6 months, LV reverse remodelling was investigated. Cardiac resynchronization therapy patients were considered responders when an absolute improvement in LV ejection fraction ≥ 5% occurred. At 6 months, 14 (56%) patients were responders and 11 (44%) non-responders (mean LVEF 40 ± 10% vs. 27 ± 6%, respectively). In responders, SonR value did not significantly change at follow-up compared to baseline (P = 0.894). At follow-up, SonR value was not significantly different between two groups (P = 0.651). SonR signal significantly increased during isometric effort in responders (P = 0.002) while it slightly decreased in non-responders at follow-up (P = 0.572). No differences were observed in response to isometric effort between two groups at baseline (P = 0.182, P = 0.069, respectively). CONCLUSIONS: The absolute SonR amplitude provides limited information on the status of LV performance. The variation in SonR signal during static exercise is more likely to identify responders at follow-up.

The Need for a Lengthier Cryolesion Can Predict a Worse Outcome in 3D Cryoablation of AV Nodal Slow Pathway in Children.

BACKGROUND: Transcatheter cryoablation is a well-established technique for the treatment of atrioventricular nodal reentry tachycardia (AVNRT) in children. Nevertheless, atrioventricular nodal slow-pathway conduction may recur after an acutely successful procedure. The aim of this study was to evaluate the long-term outcome of acutely successful AVNRT cryoablations in pediatric patients in case of focal cryolesion and in case of need for High-Density Linear Lesion (HDLL) cryoablation due to focal failure. METHODS: Sixty-nine consecutive pediatric patients (30 males, mean age 12.4 ± 3.2 years; range: 5.4-18.0 years) underwent 3D-guided cryoablation for AVNRT at our institution from July 2013 to November 2014. When a focal cryoablation was acutely unsuccessful, a 3D-guided HDLL was created delivering multiple overlapping cryolesions/cryoenergy applications from the ventricular side of the tricuspid annulus to the atrial side, including the site of focal cryoablation if transiently successful. RESULTS: No permanent cryoablation-related complications occurred. Acute success rate was 98.5% (68 out of 69): in 55.9% (38 out of 68) with focal-lesion and in 44.1% (30 out of 68) with HDLL. Mean follow-up was 25.3 months and AVNRT recurrence rate was 13.2% (nine out of 68): 5.2% (two out of 38) with focal lesion and 23.3% (seven out of 30) with HDLL (P = 0.036). CONCLUSIONS: In cryoablation of AVNRT in children, the need for a more aggressive protocol (HDLL), due to the failure of focal ablation, is strictly related to higher recurrence rates. Indeed, AVNRT recurrences after cryoablation in children seem to be due to a larger and deeper substrate rather than due to the type of energy used.

Assessment of Myocardial Contractility by SonR Sensor in Patients Undergoing Cardiac Resynchronization Therapy.

BACKGROUND: SonR sensor signal correlates well with myocardial contractility expressed in terms of left ventricular (LV) dP/dt max. The aim of our study was to evaluate the changes in myocardial contractility during isometric effort in heart failure patients undergoing cardiac resynchronization therapy (CRT) with right atrial SonR sensor. METHODS: Thirty-one patients (19 men, 65 ± 7 years, LV ejection fraction [LVEF] 28% ± 5%, in sinus rhythm) were implanted with a CRT-defibrillator (CRT-D) device equipped with SonR sensor, which was programmed in VVI mode at 40 beats/min. Twenty-four hours after implantation, each patient underwent a noninvasive hemodynamic evaluation at rest and during isometric effort, including: (1) measurement of beat-to-beat endocavitary SonR signal; (2) echocardiographic assessment; and (3) continuous measurement of blood pressure with Nexfin method (BMEYE, Amsterdam, the Netherlands). The following contractility parameters were considered: (1) mean value of beat-to-beat SonR signal; (2) mean value of LV dP/dt by Nexfin system; and (3) fractional shortening (FS) by echocardiography. RESULTS: At the third minute of the isometric effort, mean value of SonR signal significantly increased from baseline (P < 0.001). Similarly, mean value of both LV dP/dt by Nexfin and FS significantly increased compared to the resting condition (P < 0.001; P < 0.001). While in 27 (88%) patients SonR signal increased at the third minute of the isometric effort, in four (12%) patients SonR signal decreased. In these patients, both LV dP/dt by Nexfin and FS consensually decreased. CONCLUSIONS: In CRT patients, SonR sensor is able to detect changes in myocardial contractility in a consensual way like noninvasive methods such as Nexfin system and echocardiography.

Autoantibodies against ß1-Adrenergic Receptors: Response to Cardiac Resynchronization Therapy and Renal Function.

BACKGROUND: Cardiac resynchronization therapy (CRT) nonresponse remains a major clinical problem. Autoantibodies specific for the ß1-adrenergic (ß1-AAbs) and muscarinic (M2-AAbs) receptors are found in patients with chronic heart failure (HF) of various etiologies. MATERIALS AND METHODS: We retrospectively analyzed 73 HF patients (median age 67 years, 84% males, New York Heart Association II-IV, in sinus rhythm, left ventricular ejection fraction <35%) who received CRT defibrillator (CRT-D) from 2010 to 2013. ß1-AAbs and M2-AAbs were measured by enzyme-linked immunosorbent assay. Echocardiography was used to assess CRT response (reduction >15% in left ventricular end-systolic volume at 6 months follow-up). Renal function (RF) parameters (creatinine [Cr], blood urea nitrogen [BUN], estimated glomerular filtration rate [eGFR Modified Diet in Renal Disease], cystatin C [Cys-C], and neutrophil gelatinase-associated lipocalin [NGAL]) were also evaluated. RESULTS: A significantly higher percentage of patients positive for ß1-AAbs (OD sample/OD reference ratio >2.1) in nonresponders than in responder patients was observed (57% vs 27%, P = 0.004). No influence of M2-AAbs on CRT-D response was demonstrated. ß1-AAbs were predictive of a poor CRT-D response (odds ratio [OR] [95% confidence interval (CI)] 3.64 [1.49-8.88], P = 0.005), also after adjustment for RF parameters (OR [95% CI] 4.95 [1.51-16.26], P = 0.008) observed to influence CRT-D response (Cr P = 0.03, BUN P = 0.009, Cys-C P = 0.02). The positive rates of ß1-AABs in patients with abnormal blood level of Cr, eGFR, Cys-C, and NGAL were significantly higher than those with normal levels (P = 0.03, P = 0.02, P = 0.001, P = 0.007, respectively). CONCLUSIONS: Our study suggests that (1) the evaluation of ß1-AAb is useful to identify responders to CRT-D; (2) the presence of ß1-AAbs is in relationship with elevated renal function parameters.

The gut hormone ghrelin partially reverses energy substrate metabolic alterations in the failing heart.

BACKGROUND: The gut-derived hormone ghrelin, especially its acylated form, plays a major role in the regulation of systemic metabolism and exerts also relevant cardioprotective effects; hence, it has been proposed for the treatment of heart failure (HF). We tested the hypothesis that ghrelin can directly modulate cardiac energy substrate metabolism. METHODS AND RESULTS: We used chronically instrumented dogs, 8 with pacing-induced HF and 6 normal controls. Human des-acyl ghrelin [1.2 nmol/kg per hour] was infused intravenously for 15 minutes, followed by washout (rebaseline) and infusion of acyl ghrelin at the same dose. (3)H-oleate and (14)C-glucose were coinfused and arterial and coronary sinus blood sampled to measure cardiac free fatty acid and glucose oxidation and lactate uptake. As expected, cardiac substrate metabolism was profoundly altered in HF because baseline oxidation levels of free fatty acids and glucose were, respectively, >70% lower and >160% higher compared with control. Neither des-acyl ghrelin nor acyl ghrelin significantly affected function and metabolism in normal hearts. However, in HF, des-acyl and acyl ghrelin enhanced myocardial oxygen consumption by 10.2±3.5% and 9.9±3.7%, respectively (P<0.05), and cardiac mechanical efficiency was not significantly altered. This was associated, respectively, with a 41.3±6.7% and 32.5±10.9% increase in free fatty acid oxidation and a 31.3±9.2% and 41.4±8.9% decrease in glucose oxidation (all P<0.05). CONCLUSIONS: Acute increases in des-acyl or acyl ghrelin do not interfere with cardiac metabolism in normal dogs, whereas they enhance free fatty acid oxidation and reduce glucose oxidation in HF dogs, thus partially correcting metabolic alterations in HF. This novel mechanism might contribute to the cardioprotective effects of ghrelin in HF.

Visual, tactile, and contact force feedback: which one is more important for catheter ablation? Results from an in vitro experimental study.

BACKGROUND: During radiofrequency ablation, effective contact is crucial in determining lesions efficacy. OBJECTIVE: The purpose of this study was to compare operators' ability to assess contact pressure using visual and tactile feedbacks together or alone in an experimental model. METHODS: In a in vitro experimental setup replicating manual catheter manipulation and recording the applied force, evaluators were asked to identify three levels of force (first, ablation, and maximum contact) as the catheter contacted the tissue model using (1) visual feedback only by fluoroscopy, "blinded" to touch; (2) tactile feedback only, blinded to fluoroscopy; and (3) both tactile and visual feedback together. The latter was regarded as reference. The experiment was repeated using a catheter force sensing technology during robotic navigation. RESULTS: During manual navigation, tighter association was shown for the visual method than for the tactile method: median difference with reference: first contact -1 (P = .97) vs -2 (P = .90); ablation contact 2 (P = .1) vs -7 (P = .03); maximum contact 2 (P = .06) vs -28 (P = .02). Bland-Altman plot and Deming regression confirmed for the visual method the good agreement with reference and the absence of bias at any level and showed for the tactile higher values and proportional bias that reached statistical significance at ablation and maximum contact. During robotic navigation, agreement was higher for the tactile than for the visual only method. CONCLUSION: During manual navigation, visual feedback alone is in better agreement with the reference compared to the tactile only approach. During robotic navigation, agreement is looser for the visual only approach. More objective feedback of contact pressure during ablation procedures is desirable.

Larger interventricular conduction time enhances mechanical response to resynchronization therapy.

BACKGROUND: Previous studies have reported that the left ventricular (LV) pacing site is a major determinant of the hemodynamic response to cardiac resynchronization therapy (CRT). However, lead positioning in a lateral or posterolateral cardiac vein may not be optimal for every patient. The objective of this study was to assess the relationship between the right ventricular (RV)-to-LV conduction time and the systolic function during CRT on the basis of changes to LV pressure-volume loops. METHODS: Left ventricular pressure and volume data were determined using a conductance catheter during CRT device implantation in 10 patients. Four endocardial LV sites were systematically assessed at four atrioventricular delays. The RV-to-LV conduction time was measured as the time interval between spontaneous peak R waves, recorded through the RV lead and the LV catheter. RESULTS: The optimal pacing site varied among patients. However, the pacing site associated with the maximum RV-to-LV conduction time resulted in a stroke volume improvement comparable to the pacing site identified through individual hemodynamic optimization (41 ± 17 mL vs 44 ± 18 mL, P = 0.266). Moreover, the RV-to-LV conduction time recorded at each endocardial pacing site correlated positively with the increase in stroke volume (r = 0.537; P < 0.001), stroke work (r = 0.642; P < 0.001), and the pressure-derivative maximum (r = 0.646; P < 0.001) obtained with CRT. CONCLUSIONS: An optimal acute response to CRT can be obtained by positioning the LV lead at the site associated with the maximum RV-to-LV conduction time. A significant correlation appears to exist between RV-to-LV conduction time and the improvement in systolic function with CRT.

Acute hemodynamic effect of left ventricular endocardial pacing in cardiac resynchronization therapy: assessment by pressure-volume loops.

BACKGROUND: During cardiac resynchronization therapy (CRT) device implantation, the pacing lead is usually positioned in the coronary sinus (CS) to stimulate the left ventricular (LV) epicardium. Transvenous LV endocardial pacing via transseptal puncture has been proposed as an alternative method. In the present study, we evaluated the acute hemodynamic effects of CRT through LV endocardial pacing in heart failure patients by analyzing LV pressure-volume relationships. METHODS AND RESULTS: LV pressure and volume data were determined via conductance catheter during CRT device implantation in 10 patients. In addition to the standard epicardial CS pacing, the following endocardial LV sites were systematically assessed: the site transmural to the CS lead, the LV apex, the septal midwall, the basal lateral free wall, and the midlateral free wall. Four atrioventricular delays were tested. There was a significant improvement of systolic function with CRT in all LV pacing configurations, whereas no differences in systolic or diastolic function were detected between LV epicardial and endocardial transmural sites. The optimal pacing site varied among patients but was rarely related to relatively longer activation delays, as assessed by analyzing endocardial electric activation maps. Nonetheless, positioning the pacing lead at the optimal endocardial LV site in each patient significantly improved LV performance in comparison with conventional CS site stimulation (stroke volume, 83 [79-112] mL versus 73 [62-89] mL; P=0.034). CONCLUSIONS: Pacing at the optimal individual LV endocardial site yields enhanced LV performance in comparison with conventional CS site stimulation. Endocardial LV pacing might constitute an alternative approach to CRT, when CS pacing is not viable.