Optimal ablation settings of TactiFlex SE laser-cut irrigated-tip catheter: comparison with ThermoCool SmartTouch SurroundFlow porous irrigated-tip catheter.

BACKGROUND: The TactiFlex SE catheter (TFSE, Abbott) with a contact force (CF) sensor and a laser-cut irrigated-tip has recently become available but lacks a lesion quality marker. This study aimed to explore distinctions in lesion characteristics between the TFSE and the ThermoCool SmartTouch SurroundFlow catheter (STSF, Biosense Webster), which utilizes a porous irrigated tip, and to assess the most effective application settings for the TFSE. METHODS: Lesions were generated using varying settings of radiofrequency power (30-50 W), CF (10-20 g), application duration (10-40 s), and catheter orientation (perpendicular or parallel) in an ex vivo porcine model. Comparative analysis between the TFSE and STSF was conducted for lesion characteristics and incidence of steam pops using predictive models in regression analyses. RESULTS: Among 720 applications, the TFSE exhibited a significantly lower incidence of steam pops compared to the STSF (0.6% vs. 36.8%, P < 0.001). Moreover, coefficients of determination (R2) for the TFSE were higher than those for the STSF concerning lesion depth (0.710 vs. 0.541) and volume (0.723 vs. 0.618). The lesion size generated with the TFSE was notably smaller than that with the STSF under identical application settings. Additionally, to achieve a lesion depth ≥ 4.0 mm, the TFSE required an application duration 8-12 s longer than the STSF under similar settings. CONCLUSIONS: The TFSE demonstrated a lower incidence of steam pops and superior predictability in lesion size compared to the STSF. However, the TFSE necessitated a longer application duration than the STSF to achieve an adequate lesion size.

Septal coronary artery fistula after left bundle branch area pacing assessed by multi-imaging modalities and shunt volume quantification.

Septal coronary artery fistula is a rare but concerning complication of left bundle branch area pacing (LBBAP). We report the case of an 82-year-old man who was indicated for cardiac resynchronization therapy and underwent LBBAP. The patient had no chest symptoms during or after implantation. Postoperative echocardiography demonstrated a new abnormal tunnel inside the interventricular septum (IVS) and shunt flow from the IVS toward the right ventricle. Coronary angiography confirmed a septal coronary artery fistula, which might have been formed by failed deep screw attempts. Since the shunt volume assessed by the Qp /Qs was small, the patient was treated conservatively.

Efficacy of His Bundle Pacing on LV Relaxation and Clinical Improvement in HF and LBBB.

OBJECTIVES: This study aimed to compare acute hemodynamic improvements and responses to His bundle pacing (HBP) and conventional biventricular pacing (BVP). BACKGROUND: HBP can correct left bundle branch block (LBBB) and may be an alternative cardiac resynchronization therapy (CRT) to BVP. METHODS: Fourteen consecutive patients with heart failure (HF) and typical LBBB who required CRT were enrolled. The acute hemodynamic responses during HBP and BVP were compared using a micromanometer-tipped catheter inserted into the left ventricle (LV) before CRT. Each configuration was compared with AAI mode. A permanent HBP device was implanted when LBBB correction threshold was ≤1.5 V at 1.0 ms, and remaining patients were treated with BVP. Clinical and echocardiographic improvements were assessed during a 12-month follow-up period. RESULTS: The LV contractile index (positive maximal rate of LV pressure rise [dP/dtmax]) increased similarly during HBP and BVP (18.8% ± 6.4% vs 18.0% ± 10.2%; P = 0.810). LV relaxation indices (negative dP/dtmax and tau) were significantly improved during HBP compared with BVP (negative dP/dtmax: 14.3% ± 5.5% vs 3.1% ± 8.1%; P < 0.001; tau: 7.2% ± 4.3% vs -0.8% ± 8.1%; P = 0.001). Nine (64%) patients received permanent HBP devices, while 5 patients were treated with BVP. The New York Heart Association functional class, LV ejection fraction, LV end-systolic volume, and B-type natriuretic peptide level improved in patients treated with HBP and BVP (all P < 0.05 vs baseline). Patients treated with HBP exhibited earlier and greater improvements of the LV ejection fraction and LV end-systolic volume than did those with BVP. CONCLUSIONS: HBP improves systolic function and LV relaxation in patients with HF and LBBB. CRT via HBP produced earlier and greater clinical responses than BVP.

Permanent His-bundle pacing using distal His-bundle electrogram-guided approach in patients with atrioventricular block.

BACKGROUND: Permanent His-bundle pacing (HBP) is effective and safe; however, the success rate of HBP is low, especially in patients with infranodal block. This study aimed to assess the efficacy and feasibility of HBP implantation using an electrophysiological guided approach targeting a distal His-bundle electrogram (HBE) in patients with atrioventricular block (AVB). METHODS: Thirty-four consecutive patients with AVB (infranodal block in 28 patients) who underwent HBP were enrolled. During implantation, we attempted to target the distal part of the HBE (distal HBE) beyond the block site based on unipolar mapping. The His-capture threshold was evaluated for 1 year after implantation. RESULTS: HBP was achieved in 26 patients and in 21 patients (75%) with infranodal block. Detection of distal HBE was significantly higher in the successful HBP group than in the HBP failure group (65.4% vs. 0%, p = .001). Among 15 patients with intra-Hisian block, 14 patients (93%) successfully achieved HBP with distal HBE detection. During the 1-year follow-up period, an increase in His-capture threshold by ≥1.0 V at 1.0 ms occurred in five (19.2%) of 26 patients. The increased His-capture threshold group exhibited significantly less detection of distal HBE (20% vs. 76.2%; odds ratio 0.078, 95% confidence interval 0.07-0.87, p = .038) and a higher His-capture threshold at implantation (2.0 ± 1.1 V vs. 1.1 ± 0.9 V; odds ratio 1.702, 95% confidence interval 1.025-2.825, p = 0.04) than the non-increased His-capture threshold group. CONCLUSION: HBP implantation guided by distal HBE approach may be feasible with subsequent stable pacing in patients with intra-Hisian and atrioventricular nodal block.

Autopsy evaluation of the implantation site of a His bundle pacing lead demonstrating selective capture.

Evaluations of His bundle pacing (HBP) lead location at autopsy examination have been rarely reported. We report an autopsy case of a 98-year-old man who underwent HBP implantation due to atrioventricular block and heart failure. Although selective HBP was achieved with an acceptable threshold, the stimulus-to-QRS interval was relatively longer without correction of the right bundle-branch block. A macroscopic examination revealed that the HBP lead was inserted on the ventricular side passing through the anteroseptal commissure of the tricuspid valve. Transthyretin cardiac amyloidosis may affect the distal conduction system resulting in a long stimulus-to-QRS interval during selective HBP.

Impact of post-dilatation on longitudinal stent elongation: An in vitro study.

OBJECTIVES: To evaluate whether balloon inflation for post-dilatation causes longitudinal stent deformation (LSD). METHODS AND RESULTS: Two stents, sized 2.5mm×28mm and 3.5mm×28mm (Nobori®, biodegradable polymer biolimus-eluting stent; Ultimaster®, biodegradable polymer sirolimus-eluting stent; Terumo Co., Tokyo, Japan), were deployed at nominal pressure in straight and tapered silicon vessel models. Then, post-dilatation was performed in two ways: dilatation from the distal (D-P group) or proximal (P-D group) side of the stent. Microscopic findings showed that the stents were elongated during every step of the procedure regardless of the post-dilatation method and type of vessel model. The D-P group showed linear elongation during each step of post-dilatation (straight model: 28.7±0.3mm vs. 29.9±0.3mm, p=0.002; tapered model: 28.0±0.1mm vs. 29.9±0.1mm, p<0.001). In contrast, in the P-D group, the most significant change was observed in the first step of post-dilatation and only slight changes were observed thereafter (straight model: 28.6±0.1mm vs. 29.5±0.1mm, p<0.001; tapered model: 28.2±0.1mm vs. 29.5±0.1mm, p<0.001). Optical frequency domain imaging analysis showed that the frequency of stent strut malapposition was positively correlated with the percentage change in stent length (r=0.74, p<0.0001). CONCLUSION: LSD was observed during every step of post-dilatation in both the straight and tapered vessel models. However, some differences were observed between the D-P and P-D groups. Minimizing stent strut malapposition may reduce the risk of LSD.

Acute improvement of left ventricular relaxation as a predictor of volume reduction after cardiac resynchronization therapy: a pilot study assessing the value of left ventricular hemodynamic parameter.

BACKGROUND: Cardiac resynchronization therapy (CRT) improves cardiac function, but CRT recipients with advanced heart failure (HF) do not always respond well. Because the best parameters for the prediction of CRT response are not established, we investigated whether improvement of invasive left ventricular (LV) hemodynamic diastolic parameters could identify CRT responders. METHODS: A total of 34 consecutive patients (age, 69 ± 9 years; 70% men) who received CRT devices for HF were assessed as to whether acute invasive hemodynamic parameters with and without CRT function could predict LV volume responders. RESULTS: These patients demonstrated an improvement in LV dP/dtmax (11.1 ± 11.7%), LV dP/dtmin (4.6 ± 12.1%), and tau (3.7 ± 11.6%) by biventricular pacing. Nineteen patients (55%) were classified as CRT responders, which was defined by a >15% decrease in LV end-systolic volume (ESV) at the 6-month follow-up evaluation. The area under the receiver operator characteristic curve to detect CRT volume response was 0.93 for the shortening of tau, which was superior to any other hemodynamic parameter. The multivariate analysis revealed that this improvement in tau was the strongest predictive factor for identifying CRT volume responders. Of note, the magnitude of tau shortening during biventricular pacing was significantly correlated with the reduction in LVESV at the 6-month follow-up evaluation. CONCLUSIONS: The extent of acute improvement in LV isovolumic relaxation time, as assessed by tau, was associated with favorable response to CRT. The assessment of invasive diastolic function could provide valuable information about CRT volume response.

Impact of coronary stent designs on acute stent recoil.

BACKGROUND: Acute stent recoil has been often observed following stent delivery balloon deflation in coronary arteries and the recoil rate varies by stent design. Accordingly, the purpose of the present study was to evaluate the impact of stent designs on acute stent recoil after new generation drug-eluting stent implantation. METHODS AND RESULTS: A total of 154 lesions [56 treated with biolimus-eluting stent (BES), 46 with cobalt chromium everolimus-eluting stent (CoCr-EES), and 52 with platinum chromium everolimus-eluting stent (PtCr-EES)] were evaluated. Quantitative coronary angiography was used to measure the minimal lumen diameter (MLD). MLD1 was defined as a MLD of complete expansion of the last stent delivery balloon at the highest pressure. MLD2 was defined as a MLD immediately after the last stent delivery balloon deflation. Acute stent recoil was determined by the calculation as (MLD1-MLD2)/MLD1. Acute stent recoil was significantly higher in the CoCr-EES group versus the BES group and PtCr-EES group (10.1 ± 6.9%, 6.7 ± 5.5%, and 6.5 ± 4.8%, respectively, p = 0.01). Multivariate linear regression analysis demonstrated that the use of CoCr-EES and the number of stent delivery balloon inflations were independent predictors of acute stent recoil (r = 0.26, ß = 0.21, p = 0.01 and r = -0.51, ß = -0.58, p < 0.01, respectively). CONCLUSION: Acute stent recoil occurred more frequently with the CoCr-EES compared with both BES and PtCr-EES. Strategies with multiple balloon inflation might be needed to overcome this recoil phenomenon.