Concepción Alonso-Martín

Effects of Open-Irrigated Radiofrequency Ablation Catheter Design on Lesion Formation and Complications: In Vitro Comparison of 6 Different Devices

Open‐irrigated radiofrequency ablation catheters with slight differences in tip architecture are widely used, although limited comparative data are available. The purpose of this study was to compare the lesion size and potential complications produced by commercially available open‐irrigated catheters in an in vitro porcine heart model.

Pulmonary vein isolation in cases of difficult catheter placement: A new pacing maneuver to demonstrate complete isolation of the veins

BACKGROUND Pulmonary vein electrical isolation is the main goal of atrial fibrillation ablation. To ensure electrical isolation of the pulmonary veins, entrance and exit block should be demonstrated. However, this is sometimes challenging due to the complex anatomy of the pulmonary vein area and the anatomical variations that may preclude the correct position of the commonly used circular multielectrode catheter inside the veins. OBJECTIVE To describe a new pacing maneuver useful to demonstrate complete isolation of ipsilateral veins in cases of difficult catheter placement. METHODS Three representative cases illustrate the usefulness of the maneuver either at the right or left pulmonary veins. RESULTS After the circumferential ablation of ipsilateral veins, the circular catheter is positioned in one vein and the ablation catheter in the other ipsilateral vein. When local capture in one vein can be demonstrated while pacing from the other vein and no conduction to the atria is observed, isolation of both veins can be assured. CONCLUSION This novel maneuver might be of help in assessing complete isolation of the pulmonary veins in cases of difficult circular catheter placement.

Endocardial infarct scar recognition by myocardial electrical impedance is not influenced by changes in cardiac activation sequence

BACKGROUND Measurement of myocardial electrical impedance can allow recognition of infarct scar and is theoretically not influenced by changes in cardiac activation sequence, but this is not known. OBJECTIVES The objectives of this study were to evaluate the ability of endocardial electrical impedance measurements to recognize areas of infarct scar and to assess the stability of the impedance data under changes in cardiac activation sequence. METHODS One-month-old myocardial infarction confirmed by cardiac magnetic resonance imaging was induced in 5 pigs submitted to coronary artery catheter balloon occlusion. Electroanatomic data and local electrical impedance (magnitude, phase angle, and amplitude of the systolic-diastolic impedance curve) were recorded at multiple endocardial sites in sinus rhythm and during right ventricular pacing. By merging the cardiac magnetic resonance and electroanatomic data, we classified each impedance measurement site either as healthy (bipolar amplitude ≥1.5 mV and maximum pixel intensity <40%) or scar (bipolar amplitude <1.5 mV and maximum pixel intensity ≥40%). RESULTS A total of 137 endocardial sites were studied. Compared to healthy tissue, areas of infarct scar showed 37.4% reduction in impedance magnitude (P < .001) and 21.5% decrease in phase angle (P < .001). The best predictive ability to detect infarct scar was achieved by the combination of the 4 impedance parameters (area under the receiver operating characteristic curve 0.96; 95% confidence interval 0.92-1.00). In contrast to voltage mapping, right ventricular pacing did not significantly modify the impedance data. CONCLUSION Endocardial catheter measurement of electrical impedance can identify infarct scar regions, and in contrast to voltage mapping, the impedance data are not affected by changes in cardiac activation sequence.

Integration of late-enhanced MRI and electroanatomical mapping for substrate ablation of poorly tolerated ventricular tachycardia

We describe the case of a patient with a poorly tolerated ventricular tachycardia (VT) in which a substrate ablation was performed. The ablation was guided by the integrated images of the scar obtained by MRI and electro-anatomical mapping. This combined technique can make substrate ablation more accurate and may have a role in the ablation of unmappable VT.

Identification of the critical isthmus of a reentrant ventricular tachycardia at a glance

A 61-year-old male with prior inferior myocardial infarction was referred for catheter ablation of a monomorphic ventricular tachycardia (VT). His left ventricular ejection fraction was 45% and a cardiac magnetic resonance showed late gadolinium enhancement at the inferobasal left ventricle. Detailed endocardialmapping of the left ventricle was performed during sinus rhythm, using the multielectrode catheter Pentaray and the CARTO 3 mapping system (Biosense Webster, Inc., Diamond Bar, CA, USA). A low-voltage area (<1.5 mV) was identified at the inferobasal left ventricle. During VT, tiny diastolic potentials were recorded along the entirely VT cycle length at the septal border of the scar (Figure 1A and B). Following the sequence of activation of the diastolic potentials recorded by the multipolar catheter, we were able to reconstruct the activation along the critical isthmus of the VT that was confirmed by entrainment maneuvers. Interestingly, spontaneous termination of the VT showed that most of the diastolic potentials recorded during VT were canceled by the ventricular electrogram during sinus rhythm at the same location, and therefore, difficult to identify by voltage criteria. This emphasizes how the configuration of the recorded electrograms is influenced by the wave front activation and suggests that at least part or the isthmuswas functional. Pacing during sinus rhythm from different poles of the Pentaray catheter identified nonexcitable tissue in close proximity to the critical isthmus, leading to a better delimitation of the substrate involved in the VT circuit. Radiofrequency applications across the isthmus terminatedVTand rendered the tachycardia not inducible. The case illustrates the potential of the simultaneous recording from multiple small electrodes in improving our understanding of the VT substrate.

Pacemaker-mediated tachycardia in the absence of retrograde ventriculoatrial conduction: What is the mechanism?: MÉNDEZ-ZURITA et al.

A 49-year-old man with a complex congenital heart disease (comprising dextrocardia with situs solitus, atrial septal defect, ventricular septal defect, severe pulmonary stenosis and D- transposition of the great arteries surgically repaired by means of the Rastelli procedure at the age of 22 years) underwent single-chamber defibrillator (ICD) implantation for primary prevention of sudden cardiac death due to severe systolic dysfunction of the systemic ventricle. The right ventricular lead (RV; Durata 7120, St. Jude Medical TM, Sylmar, CA, US) was implanted using a conventional transvenous approach. Two years later the patient developed heart failure symptoms and the ECG showed sinus rhythm with first degree AV block and left bundle branch block QRS morphology. Therefore, upgrade to cardiac resynchronization therapy (Unify 3235-40Q CRT-D, St Jude Medical TM, Sylmar, CA, US) was performed in 2012. Two epicardial leads were surgically implanted in the left atrium (LA; Miopore 511212, Greatbatch medical TM) and left ventricle (LV; 6071, Medtronic TM, Minneapolis, US). The X-ray lead positioning is shown in Figures 1A and 1B.

Comparison between endocardial and epicardial cardiac resynchronization in an experimental model of non-ischaemic cardiomyopathy

Aims Pacing from the left ventricular (LV) endocardium might increase the likelihood of response to cardiac resynchronization therapy. However, experimental and clinical data supporting this assumption are limited and controversial. The aim of this study was to compare the acute response of biventricular pacing from the LV epicardium and endocardium in a swine non-ischaemic cardiomyopathy (NICM) model of dyssynchrony. Methods and results A NICM was induced in six swine by 3 weeks of rapid ventricular pacing. Biventricular stimulation was performed from 16 paired locations in the LV (8 epicardial and 8 endocardial) with two different atrioventricular (80 and 110 ms) intervals and three interventricular (0, +30, -30 ms) delays. The acute response of the aortic blood flow, LV and right ventricular (RV) pressures, LVdP/dtmax and LVdP/dtmin and QRS complex width and QT duration induced by biventricular stimulation were analysed. The haemodynamic and electrical beneficial responses to either LV endocardial or epicardial biventricular pacing were similar (ΔLVdP/dtmax: +7.8 ± 2.2% ENDO vs. +7.3 ± 1.5% EPI, and ΔQRS width: -16.8 ± 1.3% ENDO vs. -17.1 ± 1.9% EPI; P = ns). Pacing from LV basal regions either from the epicardium or endocardium produced better haemodynamic responses as compared with mid or apical LV regions (P < 0.05). The LV regions producing the maximum QRS complex shortening did not correspond to those inducing the best haemodynamic responses (EPI: r2 = 0.013, P = ns; ENDO: r2 = 0.002, P = ns). Conclusion Endocardial LV pacing induced similar haemodynamic changes than pacing from the epicardium. The response to endocardial LV pacing is region dependent as observed in epicardial pacing.

ECG de octubre de 2014

The patient was a 63-year-old man with a history of dyslipidemia under treatment with simvastatin, Barrett’s esophagus being treated with omeprazole, recent occupational stress being treated with loprazolam, and hypertension for which he was taking enalapril. The only noteworthy findings in his echocardiogram were a nondilated left ventricle with an ejection fraction of 73%, moderate septal hypertrophy (14 mm), and degenerative aortic valve disease with moderate regurgitation. He sought medical attention complaining of episodes of rapid-onset syncope. During his stay in the emergency department, he experienced 2 episodes that required electrical cardioversion. Figures 1–3 show the rhythm strips recorded from lead III during the episodes, 12-lead electrocardiogram during tachycardia and the baseline electrocardiogram at hospital admission.

An Unusual Onset of Supraventricular Tachycardia with 2:1 Atrioventricular Block: What Is the Mechanism?

A 61-year-old male patient with a history of valvular and ischemic cardiomyopathy and low left ventricular ejection fraction (33%) was referred to our institution for palpitation episodes over the last 3 months. Two ECGs from the hospital of origin showed a regular, wide QRS complex tachycardia with left bundle branch block (LBBB) morphology at a cycle length of 360 milliseconds (Fig. 1A). In both ECGs, a narrow QRS complex was recorded during tachycardia. The tachycardia was terminated with an amiodarone bolus of 300 mg on both occasions, and the 12-lead ECG during sinus rhythm showed a normal QRS complex. At admission to our center, an electrophysiological study was performed. Two quadripolar catheters were positioned in the high right atrium and in the His bundle region, respectively. Baseline AH interval was 95 milliseconds and HV interval was 65 milliseconds. Incremental atrial pacing and atrial programmed stimulation showed continuous AH lengthening. Ventricular pacing showed poor retrograde ventriculoatrial conduction through the AV node. Retrograde dual pathway physiology and a single atypical AV nodal echo were documented at baseline. Supraventricular tachycardia was not induced either by atrial or ventricular stimulation. Programmed ventricular stimulation was then performed from the apex of the right ventricle with 3 cycle lengths and coupling of up to 3 extrastimuli, without inducing ventricular tachycardia (VT). During isoproterenol infusion (2 μg/min), a narrow QRS complex tachycardia with a long VA interval was repeatedly induced by atrial and ventricular stimulation (Fig. 1B). In a few episodes, delivery of atrial single extrastimulus at decre-

Ablación, marcapasos, resincronización y desfibrilador automático implantable

Las arritmias son, sin duda, uno de los mayores problemas para el clinico a cargo de pacientes adultos con cardiopatias congenitas. Su protagonismo en el momento actual es incuestionable, pero a medida que los pacientes con cardiopatias reparadas en edad pediatrica envejezcan, es esperable que el impacto de las complicaciones arritmicas aumente. Ademas, por diferentes motivos, las cardiopatias congenitas se apartan del manejo electrofisiologico habitual. En este capitulo nos disponemos a abordar de forma resumida las particularidades que las cardiopatias congenitas suponen para el especialista en arritmias, con un breve acercamiento a la terapia de resincronizacion cardiaca para el manejo de la insuficiencia cardiaca.