Publications by authors named "Johanna Tonko"

Article Synopsis
  • Alterations in repolarization gradients contribute significantly to the development of ventricular arrhythmias, especially in patients with varying heart conditions.
  • High-density repolarization mapping can enhance the understanding of these abnormalities and help localize arrhythmogenic areas more effectively during procedures like ablation.
  • Despite its potential benefits, repolarization mapping faces practical and technical challenges that limit its routine use, necessitating further research and improvements to integrate it into standard clinical practices.
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Article Synopsis
  • * Researchers analyzed high-density contact maps from 23 patients, finding that the WS method provided significantly higher CV estimates in both sinus rhythm and ventricular ectopy compared to LAT-based methods, with differences ranging from 0.1 m/s to 0.81 m/s.
  • * The results suggest that the choice of CV estimation method can greatly affect measurements, highlighting the need for further research on the implications of these differences in clinical settings.
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Aims: Successful ventricular arrhythmia (VA) ablation requires identification of functionally critical sites during contact mapping. Estimation of the peak frequency (PF) component of the electrogram (EGM) may improve correct near-field (NF) annotation to identify circuit segments on the mapped surface. In turn, assessment of NF and far-field (FF) EGMs may delineate the three-dimensional path of a ventricular tachycardia (VT) circuit.

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Article Synopsis
  • - The study evaluated the effectiveness of two PVC ablation techniques: multipolar mapping using a high-density catheter and point-by-point mapping with the ablation catheter, involving 698 patients across 10 hospitals from 2017 to 2021.
  • - Results revealed that the multipolar group had significantly better mapping efficiency (more activation points) and shorter procedure times, while both groups showed high acute success rates and midterm efficacy.
  • - Notably, patients undergoing left-sided PVC ablation had better midterm outcomes with the multipolar method, suggesting it may lead to more successful results in certain cases.
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Myocardial microvasculature and haemodynamics are indicative of potential microvascular diseases for patients with symptoms of coronary heart disease in the absence of obstructive coronary arteries. However, imaging microvascular structure and flow within the myocardium is challenging owing to the small size of the vessels and the constant movement of the patient's heart. Here we show the feasibility of transthoracic ultrasound localization microscopy for imaging myocardial microvasculature and haemodynamics in explanted pig hearts and in patients in vivo.

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Objective: This study aimed to realise 3-D super-resolution ultrasound imaging transcutaneously with a row-column array which has far fewer independent electronic channels and a wider field of view than typical fully addressed 2-D matrix arrays. The in vivo image quality of the row-column array is generally poor, particularly when imaging non-invasively. This study aimed to develop a suite of image formation and post-processing methods to improve image quality and demonstrate the feasibility of ultrasound localisation microscopy using a row-column array, transcutaneously on a rabbit model and in a human.

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Ventricular arrhythmias in cardiac channelopathies are linked to autonomic triggers, which are sub-optimally targeted in current management strategies. Improved molecular understanding of cardiac channelopathies and cellular autonomic signalling could refine autonomic therapies to target the specific signalling pathways relevant to the specific aetiologies as well as the central nervous system centres involved in the cardiac autonomic regulation. This review summarizes key anatomical and physiological aspects of the cardiac autonomic nervous system and its impact on ventricular arrhythmias in primary inherited arrhythmia syndromes.

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Article Synopsis
  • * While these procedures offer new options for patients who can't use traditional methods, they still carry significant risks like myocardial perforation and damage to surrounding organs.
  • * The paper evaluates 10 epicardial access techniques, discussing their success rates, safety, costs, and future techniques that are still in preclinical testing.
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Electrical conduction through cardiac muscle fibres separated from the main myocardial wall by layers of interposed adipose tissue are notoriously difficult to target by endocardial ablation alone. They are a recognised important cause for procedural failure due to the difficulties of delivering sufficient energy via the endocardial radiofrequency catheter to reach the outer epicardial layer without risking adverse events of the otherwise thin walled atria. Left atrial ablations for atrial fibrillation (AF) and tachycardia are commonly affected by the presence of several epicardial structures, with the septo-pulmonary bundle (SPB), Bachmann's bundle, and the ligament of Marshall all posing substantial challenges for endocardial procedures.

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Background: Automaticity is the dominant mechanism in maternal focal atrial tachycardia (FAT) during pregnancy and if incessant, can cause tachycardia-induced cardiomyopathy. Medication failure for FATs is common, however, for the subgroup due to increased automaticity ivabradine sensitivity has been described and may represent a valuable treatment option. Little data are available regarding the safety profile of ivabradine during pregnancy.

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The high prevalence of atrial fibrillation (AF) in the overall population and its association with substantial morbidity, increased mortality and health care cost has instigated significant basic and clinical research efforts over recent years. The publication of multiple new high-quality randomized multi-center trials in the area of AF management and the rapidly evolving technological progress in terms of diagnostic possibilities and catheter ablation in recent years demanded a revision of the previous ESC AF Guidelines from 2016. The 2020 guidelines provide up-to-date, evidence-based guidance for the management of AF.

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Implantable cardioverter-defibrillators (ICDs) have revolutionized the treatment of acquired or inherited cardiac diseases associated with a high risk of sudden cardiac death due to ventricular tachyarrhythmias. Contemporary ICD devices offer reliable arrhythmia detection and discrimination algorithms and deliver highly efficient tachytherapies. Percutaneously inserted transvenous defibrillator coils with pectoral generator placement are the first-line approach in the majority of adults due to their extensively documented clinical benefit and efficiency with comparably low periprocedural implantation risks as well as the option of providing pain-free tachycardia treatment via anti-tachycardia pacing (ATP), concomitant bradycardiaprotection, and incorporation in a cardiac resynchronization therapy if indicated.

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Background: Epicardial ICD systems and CRT-Ds using high voltage coils represent an alternative to transvenous systems in patients without central venous access and prior device complications including infection.

Objective: We present a case series in the adult population of epicardial ICD/CRTD systems using high voltage epicardial coils. We summarize the existing data regarding techniques, efficacy, and safety.

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Article Synopsis
  • * This technique is particularly useful when there are complicated blockages in the central veins.
  • * Research indicates that this method is both feasible and safe for patients undergoing these procedures.
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Aims: Cardiac resynchronization therapy (CRT) has become an important therapy in patients with heart failure with reduced left ventricular ejection fraction (LVEF). The effect of diabetes on long-term outcome in these patients is controversial. We assessed the effect of diabetes on long-term outcome in CRT patients and investigated the role of diabetes in ischaemic and non-ischaemic cardiomyopathy.

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