Róbert Pap

Noninvasive assessment of left ventricular contractility by pacemaker stress echocardiography

Estimating contractility of the left ventricle with noninvasive techniques is an important yet elusive goal. Positive inotropic interventions are mirrored by smaller end‐systolic volumes and higher end‐systolic pressures. An increased heart rate progressively increases the force of ventricular contraction (Bowditch treppe or staircase phenomenon).

Is there a relationship between complex fractionated atrial electrograms recorded during atrial fibrillation and sinus rhythm fractionation

BACKGROUND Ablation of persistent atrial fibrillation (AF) may require adjunctive methods of substrate modification. Both ablation-targeting complex fractionated atrial electrograms (CFAEs) recorded during AF and fractionated electrograms recorded during sinus rhythm (sinus rhythm fractionation [SRF]) have been described. However, the relationship of CFAEs with SRF is unclear. METHODS Twenty patients (age 62 ± 9 years, 13 males) with persistent AF and 9 control subjects without organic heart disease or AF (age 36 ± 6 years, 4 males) underwent detailed CFAE and SRF left atrial electroanatomic maps. The overlap in left atrial regions with CFAEs and SRF was compared in the AF population, and the distribution of SRF was compared among patients with AF and normal controls. Propagation maps were analyzed to identify the activation patterns associated with SR fractionation. RESULTS SRF (338 ± 150 points) and CFAE (418 ± 135 points) regions comprised 29% ± 14% and 25% ± 15% of the left atrial surface area, respectively. There was no significant correlation between SRF and CFAE maps (r = .2; P = NS). On comparing patients with AF and controls, no significant difference was found in the distribution of SRF between groups (P = .74). Regions of SRF overlapped areas of wave-front collision 75% ± 13% of the time. CONCLUSIONS (1) There is little overlap between regions of CFAEs during AF and regions of SRF measured in the time domain or the frequency domain, (2) the majority of SRF appears to occur in regions with wave-front collision, (3) the distribution of SRF is similar in patients with AF and normal controls, suggesting that this may not have an important role in AF maintenance and may not be a suitable ablation target.

Characterization of a novel multifunctional resveratrol derivative for the treatment of atrial fibrillation

Atrial fibrillation (AF) is the most common cardiac arrhythmia and is associated with an increased risk for stroke, heart failure and cardiovascular‐related mortality. Candidate targets for anti‐AF drugs include a potassium channel Kv1.5, and the ionic currents IKACh and late INa, along with increased oxidative stress and activation of NFAT‐mediated gene transcription. As pharmacological management of AF is currently suboptimal, we have designed and characterized a multifunctional small molecule, compound 1 (C1), to target these ion channels and pathways.

Ablation of Posteroseptal and Left Posterior Accessory Pathways Guided by Left Atrium–Coronary Sinus Musculature Activation Sequence

Introduction: While some posteroseptal and left posterior accessory pathways (APs) can be ablated on the tricuspid annulus or within the coronary venous system, others require a left‐sided approach. “Fragmented” or double potentials are frequently recorded in the coronary sinus (CS), with a smaller, blunt component from left atrial (LA) myocardium, and a larger, sharp signal from the CS musculature.

Thin basement membrane nephropathy: Diffuse and segmental types

CONTEXT Diffuse thinning of the glomerular basement membrane (GBM) is the ultrastructural diagnostic criterion of thin basement membrane nephropathy (TBMN). However, there is no consensus regarding what diagnosis should be made if the attenuation is segmental. OBJECTIVE To develop a diagnostic approach to TBMN in cases with segmental GBM thinning. DESIGN We compared the diagnostic sensitivities of 2 methods used for the quantitative expression of GBM width in a consecutive series of renal biopsies from 26 patients (median age, 36 years; range, 15 to 59 years) with dysmorphic hematuria (a variable degree of proteinuria in 19 patients), a thin GBM, and absence of other renal disease. The harmonic GBM width was determined from orthogonal intercepts, and the actual width in the thinnest loops was obtained by direct measurement. The GBM attenuation was categorized into diffuse or segmental types by conventional inspection. RESULTS Segmental TBMN accounted for one third of the series. In neither type did the male patients have a higher harmonic mean GBM width than the female patients. Focal-global glomerulosclerosis was more common in diffuse TBMN. The laborious orthogonal intercept method proved insensitive for the verification of segmental TBMN, whereas the much simpler direct measurement technique captured all the cases. CONCLUSIONS A considerable number of patients with TBMN display segmental GBM attenuation. Because the routine criterion excludes these cases from the diagnosis, we propose to define TBMN as a clinicopathologic entity of dysmorphic hematuria and a diffusely or segmentally thinned GBM confirmed by the direct measurement technique.

Randomized Trial of Intracardiac Echocardiography During Cavotricuspid Isthmus Ablation

Randomized Trial of ICE During CTI Ablation. Introduction: Despite a high success rate, radio‐frequency ablation (RFA) of the cavotricuspid isthmus (CTI) can be unusually challenging in some cases. We postulated that visualization of the CTI with intracardiac echocardiography (ICE) could maximize the succes rate, decrease the procedure and ablation time, and minimize the radiation exposure.

Frequency Domain Mapping of Atrial Fibrillation - Methodology, Experimental Data and Clinical Implications

The concept of dominant frequency (DF) has been used as a way to express local atrial activation rate during atrial fibrillation (AF). The rotor theory explaining the pathophysiology of AF is widely based upon spatial distribution of DF in the atria. Using frequency domain analysis to represent the rate of atrial activation by DF can avoid some of the limitations of time domain analysis of signals during AF. Understanding the concept of DF is of utmost importance to the proper use and interpretation of frequency domain analysis in AF. The current review focuses on the basic principles and methodology of frequency domain analysis using the Fourier transform during different types of AF. It also provides an update of the published experimental and clinical data on frequency domain analysis in light of the rotor theory for AF maintenance.

Ventricular location of a part of the right atrial isthmus after tricuspid valve replacement for Ebstein’s anomaly: a challenge for atrial flutter ablation

We report the case of a patient with atrial flutter late after tricuspid valve replacement for Ebstein’s anomaly. Computed tomographic angiography revealed that coronary sinus ostium and part of the right atrial isthmus were located on the ventricular side of the valve ring due to the specific surgical approach in this condition. Based on the results of electroanatomic mapping and entrainment, the arrhythmia was found to be cavotricuspid isthmus dependent clockwise atrial flutter. Completion of the isthmus line required ablation lesions across the artificial valve. When these were delivered the arrhythmia terminated and isthmus block was achieved. Due to arrhythmia recurrence a redo procedure was performed which demonstrated conduction recovery in the ventricular part of the cavotricuspid isthmus. Intracardiac ultrasound-guided ablation successfully eliminated conduction across the isthmus with subsequent freedom from arrhythmia on follow up.

Intracardiac echocardiography in a case with previous failed cavotricuspid isthmus ablation

The Eustachian ridge (ER) can present an obstacle to cavotricuspid isthmus (CTI) ablation. We describe a case, where intracardiac echocardiography revealed a prominent ER as a likely reason for a previous failed CTI ablation and guided the looping of the ablation catheter around the ER, resulting in an ultimately successful ablation.

Intracardiac echocardiography for visualization of the Eustachian valve during radiofrequency ablation of typical atrial flutter

We performed a conventional, fluoroscopy-guided ablation of ongoing typical atrial flutter at the preferred isthmus site. Despite 150 min of procedure time (using a 4 mm, irrigated tip catheter with settings of 43°C, 40 W and …