Spatial correction improves accuracy of catheter positioning during ablation of premature ventricular contractions: differences between ventricular outflow tracts and other localizations

BACKGROUND

Hybrid activation mapping is a novel tool to correct for spatial displacement of the mapping catheter due to asymmetrical contraction of myocardium during premature ventricular contractions (PVC). The aim of this study is to describe and improve our understanding of spatial displacement during PVC mapping as well as options for correction using hybrid activation mapping.

METHODS AND RESULTS

We analyzed 5798 hybrid mapping points in 40 acquired hybrid maps of 22 consecutive patients (age 63 ± 16 years, 45% female) treated for premature ventricular contractions (PVCs). Median PVC-coupling interval was 552 ms (IQR 83 ms). Spatial displacement was determined by measuring the dislocation of the catheter tip during PVC compared to the preceding sinus beat. Mean spatial displacement was 3.8 ± 1.5 mm for all maps. The displacement was 1.3 ± 0.4 mm larger for PVCs with non-outflow-tract origin compared to PVCs originating from the ventricular outflow tracts (RVOT/LVOT; p = 0.045). Demographic parameters, PVC-coupling-interval and chamber of origin had no significant influence on the extent of spatial displacement.

CONCLUSION

Ectopic activation of the ventricular myocardium during PVCs results in spatial displacement of mapping points that is significantly larger for PVCs with non-outflow-tract origin. The correction for spatial displacement may improve accuracy of radiofrequency current (RFC)-application in catheter ablation of PVCs.

Early recurrences after catheter ablation for atrial tachycardia: do we need a blanking period?

Funding Acknowledgements

Type of funding sources: None.

Background

A blanking period after catheter ablation for atrial fibrillation is widely accepted. The clinical implications of early recurrences (ER) after ablation for atrial tachycardia (AT) in patients with a history of atrial fibrillation have not been analysed so far.

Purpose

To characterise ER and their relationship with late recurrences (LR) after AT ablation.

Methods

Acute and long-term outcome was studied in a total of 250 patients undergoing catheter ablation for consecutive AT. ER were defined as any documented atrial arrhythmia >30 s within 3 months after ablation.

Results

In our study population (66.5±0.7 years, 57.6% male), ER were detected in 80 patients (32.0%), with 74.0% of episodes occurring during the first month post-ablation. Patients with ER had a longer history of any atrial arrhythmia (9.1±0.9 years vs. 6.5±0.4 years; P=0.0283), a larger left atrial diameter (65.7±3.1 mm vs. 49.4±1.4 mm; P=0.0163) and a lower left ventricular ejection fraction (50.8±1.1% vs. 56.6±0.6%; P<0.0001) than those without ER. In patients with ER, AT were more often found to be mitral isthmus-dependent (16.5% vs. 6.2%; P=0.0048) or located at the crista terminalis (3.7% vs. 0.4%; P=0.0343). ER were associated with a 6.0-fold (95% CI 3.27-10.81; P<0.0001) and a 4.3-fold (95% CI 1.72-10.72; P=0.0023) increase in the risk of developing LR after a single or multiple ablation procedures, respectively (Figure). After a mean follow-up of 570±23 days, LR were detected in 78.0% vs. 76.9% vs. 50.0% of patients experiencing the first ER during the first, second or third month (P=0.2266). Among these groups, the first LR occurred after 188.7±20.2 days vs. 259.6±59.1 days vs. 400.8±55.5 days (P=0.0459).

Conclusions

ER after AT ablation are a predictor of LR and clinical as well as procedural risk factors are associated with the occurrence of ER. The prevalence of LR does not differ among patients with early vs. late ER. These findings underline the prognostic importance of ER and challenge the concept of a blanking period after catheter ablation for AT in patients with a history of atrial fibrillation.

Selective intracardiac sympathetic denervation acutely modulates left ventricular control

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): German Centre for Cardiovascular Research (DZHK)

Background

The sympathetic nervous system plays an integral role in cardiac physiology. Neuromodulation is emerging as a treatment option for ventricular arrhythmias, but selective intracardiac approaches are rare. Sympathetic nerve fibers innervating the left ventricle have been demonstrated to be amenable to transvenous catheter stimulation along the coronary sinus (CS).

Purpose

The aim of the present study was to modulate left ventricular control by selective sympathetic denervation using epicardial or standard catheter ablation for intracardiac axotomy at the level of the CS.

Methods

First, the impact of epicardial CS ablation on cardiac electrophysiology was studied in a Langendorff model of murine hearts (n=10 each, ablation and control). Second, the impact of transvenous, anatomically-driven axotomy by catheter-based radiofrequency ablation along the CS was evaluated in a healthy ovine in vivo model (n=8) before and during left stellate ganglion stimulation (LSGS).

Results

CS ablation for intracardiac sympathetic axotomy prolonged epicardial ventricular refractory period (VRP) without (41.8±8.4 ms vs. 53.0±13.5 ms; P=0.0487) and with beta1-2-adrenergic receptor blockade (47.8±2.8 ms vs. 73.1±5.0 ms; P=0.0009) and enhanced the increasing effect of beta1-2-adrenergic receptor blockade on epicardial VRP (∆VRP 6.3±7.0 ms vs. 20.0±7.5 ms; P=0.0045) in mice (Figure, A). Mean epicardial wave propagation velocity in the left ventricle was faster in ablated hearts than in controls (1.13±0.05 m/s vs. 1.00±0.02 m/s; P=0.0463), but did not differ in the right ventricle (1.15±0.05 m/s vs. 1.20±0.08 m/s; P=0.7938). Transvenous catheter ablation of the CS reduced systolic (SBP, 57.7±5.0 mmHg vs. 46.9±3.6 mmHg; P=0.0428) and diastolic blood pressure (DBP, 35.5±3.0 mmHg vs. 26.7±1.8 mmHg; P=0.0106) and diminished the blood pressure increase during LSGS in sheep (∆SBP 21.9±3.8 mmHg vs. 10.5±4.2 mmHg; P=0.0234; ∆DBP 9.0±1.9 mmHg vs. 3.0±1.2 mmHg; P=0.0391) (Figure, B, C). Cycle length remained unchanged by LSGS, both before (baseline 653.2±20.6 ms vs. LSGS 627.8±27.5 ms; P=0.2309) and after CS ablation (baseline 734.8±24.2 ms vs. LSGS 746.2±37.3 ms; P=0.7145).

Conclusions

Anatomically-driven axotomy targeting nerve fibers along the CS enables selective intracardiac sympathetic denervation resulting in acute modulation of left ventricular control.

Global cardiac sympathetic denervation is associated with diffuse myocardial fibrosis in non-ischemic cardiomyopathy

Funding Acknowledgements

Type of funding sources: None.

Background

 

Occurrence of ventricular tachycardias (VT) has been related to changes in sympathetic innervation and myocardial tissue in ischemic cardiomyopathy. In non-ischemic cardiomyopathy (NICM) patients with VT, the relation between global cardiac sympathetic innervation and non-ischemic fibrosis is less clear. The current gold standard in electrophysiology to identify non-ischemic fibrosis relies on unipolar endocardial voltage mapping.

Objective

To establish the relationship between global cardiac sympathetic innervation and global fibrosis.

Methods

29 patients (93% male, 58 ± 14 years, mean LVEF 38%±13) from the ‘Leiden Nonischemic Cardiomyopathy Study’ undergoing VT ablation between 2011-2018 were included. Endocardial voltage mapping was performed and the mean endocardial unipolar voltage (UV) was taken as a surrogate for global fibrosis. Global cardiac sympathetic innervation was analyzed by 123-I-MIBG imaging using heart-to-mediastinum ratio (HMR). A cut-off of 1.8 was used to delineate between normal (>1.8) and denervated (<1.8). HMR was correlated with mean UV.

Results

For patients with global cardiac sympathetic denervation a linear relationship was present between HMR and mean UV (R = 0.5278, P = 0.0431. There was no significant linear relationship for patients with normal cardiac sympathetic innervation between HMR and mean UV (R=-0.1696, P = 0.5795).

Conclusion

Global cardiac sympathetic denervation is related to myocardial fibrosis in patients with NICM and VT. The data support an interplay between denervation and fibrosis which may contribute to arrhythmogeneity, as observed in ICM. Abstract Figure.

Sympathetic innervation pattern in NICM patients with ventricular tachycardia -anteroseptal versus inferolateral substrates-

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation - Projektnummer 447558597)

Background

Among patients with non-ischemic cardiomyopathy (NICM) two dominant ventricular tachycardia (VT) substrate locations, namely anteroseptal (AS) and inferolateral (IL), have been identified. The poor outcome after catheter ablation of AS substrates (ASS) compared to IL substrates (ILS) has been attributed to its deep intramural location. However, region specific tissue charateristics, including sympathetic innervation, as important determinant of arrhythmogeneity, may also contribute to the outcome disparity.

Aim

To evaluate the association between regional sympathetic denervation, myocardial fibrosis and VT substrates according to two dominant VT substrate locations.

Methods

Twenty-nine patients from the ‘Leiden Nonischemic Cardiomyopathy Study’, who underwent electroanatomical substrate mapping and radiofrequency catheter ablation (RFCA), LGE-CMR and 123-I-MIBG imaging between 2011-2018 were included. The 16-segment model was used to describe the distribution of endocardial low unipolar voltage (UV <25th IQR) (=electroanatomical surrogate for fibrosis), the location of abnormal local electrograms and VT related sites (= surrogate for VT substrate) and the presence of LGE. Regional cardiac sympathetic innervation was determined by 123-I-MIBG imaging and analyzed according to the 16-segment model. Regions with sympathetic denervation were correlated with low UV areas, VT substrate location and LGE. Patients were categorized according to the dominant VT substrate location in ASS or ILS.

Results

Ten patients had a dominant ASS, 12 patients a dominant ILS and 1 patient had ASS and ILS; 6 patients had other VT substrate locations. All but one patient with ASS and one with ILS also showed corresponding low UV (=surrogate for fibrosis) in segments with VT substrates. Eight patients with IL VT substrates but only 4 with AS substrates showed corresponding LGE in the VT related segments. All patients with inferolateral VT substrates showed sympathetic denervation in IL segments (100% matching segments), but only 3/11 (27%) with anteroseptal substrates had sympathetic denervation in AS segments (P = 0.0002). UV was not significantly different between matching (VT substrate and denervation) and not matching ASS segments (5.74 ± 2.69 mV vs. 4.64 ± 1.85 mV, P = 0.78) and between matching ASS and ILS segments (5.74 ± 2.69 mV vs. 7.61 ± 2.91, P = 0.43). LGE location was matching with sympathetic denervation in all patients with ILS but only in 33% of patients with ASS.

Conclusion

Despite low endocardial UV (=surrogate for fibrosis) for AS and IL segments harboring VT substrates, regional sympathetic denervation coincided with fibrosis only for IL VT substrates. The mismatch between regional fibrosis and preserved innervation for AS VT substrates may contribute to a VT substrate difficult to control by RFCA.

Outcome after practical isthmus ablation of scar-related atrial tachycardia guided by high-density mapping

Background

High-density mapping (HDM) has been found to precisely identify the practical isthmus of scar-related atrial tachycardia (AT) circuits. Since practical isthmuses have been found to be shorter than the usual anatomical isthmuses targeted ablation has been proposed. However, outcome data are sparse. Here we describe HDM-guided catheter ablation by targeting the practical isthmus in patients with scar-related ATs.

Methods and results

In 250 consecutive patients with scar-related ATs HDM-guided catheter ablation with the support of a 64-electrode mini-basket catheter has been performed. Most patients underwent a prior catheter ablation (98%) while 13% had a prior cardiac valve surgery and 6% an underlying congenital heart disease. A total of 355 ATs occurred in the index procedure, of which 64% had a macro-, 26% a micro-reentry and 10% a focal mechanism. The ATs had a mean cycle length of 304±4.3 ms and in 237 patients (95%) an acute termination into sinus rhythm was achieved. They were mainly located in the left atrium (72%) but also in the right atrium (25%), bi-atrially (5%) or in the CS (3%) (see figure). Targeting the practical isthmus revealed arrhythmia freedom in 53% of patients after a single procedure during a mid-term follow-up (median 489 days, range 95–1407 days). Freedom from any arrhythmia could be achieved in 74% of patients after multiple procedures and in 93% of patients after multiple procedures and optimal clinical therapy, including pharmaceutical or electrical cardioversion.

Conclusions

HDM-guided catheter ablation of the practical isthmus in patients with scar-related ATs leads to a high acute success rate. Nevertheless, multiple procedures are necessary in a relevant number of patients resulting in a low recurrence rate.

Funding Acknowledgement

Type of funding source: None

Quantum beats and Kepler motion in fast competing photoionization and photodissociation processes

Electronic and nuclear wavepackets created by coherent excitation of an autoionized and predissociated 'complex' resonance in H2 are studied theoretically using time-dependent multichannel quantum defect theory. The calculations predict that quantum beats between the components of the complex resonance interfere with Rydberg wavepacket (Kepler) motion to yield characteristic 'mixed' flux patterns in the observable time-dependent ionization and dissociation signals.

The Electronic Structure of CaCl: Calculation by R Matrix and Generalized Quantum Defect Theory

The electronic spectrum of CaCl has been calculated using the variational eigenchannel R-matrix method combined with generalized multichannel quantum defect theory. The motion of the unpaired (Rydberg) electron is represented as a double scattering process on the closed-shell Ca(++) and Cl(-) core ions. Electron penetration into Ca(++) is taken into account as well as polarization effects. The partial saturation of the Cl(-) free-ion polarizability is evaluated on the basis of an ab initio calculation of the dipole and quadrupole moments of the CaCl(+) ion core. The calculations reproduce the effective principal quantum numbers nu of the experimentally known states (including the ground state) to within approximately 0.04. States with high-orbital angular momentum up to l = 6 are predicted. Copyright 1999 Academic Press.