Subject-Specific Calculation of Left Atrial Appendage Blood-Borne Particle Residence Time Distribution in Atrial Fibrillation

Atrial fibrillation (AF) is the most common arrhythmia that leads to thrombus formation, mostly in the left atrial appendage (LAA). The current standard of stratifying stroke risk, based on the CHA2DS2-VASc score, does not consider LAA morphology, and the clinically accepted LAA morphology-based classification is highly subjective. The aim of this study was to determine whether LAA blood-borne particle residence time distribution and the proposed quantitative index of LAA 3D geometry can add independent information to the CHA2DS2-VASc score. Data were collected from 16 AF subjects. Subject-specific measurements included left atrial (LA) and LAA 3D geometry obtained by cardiac computed tomography, cardiac output, and heart rate.We quantified 3D LAA appearance in terms of a novel LAA appearance complexity index (LAA-ACI). We employed computational fluid dynamics analysis and a systems-based approach to quantify residence time distribution and associated calculated variable (LAA mean residence time, tm) in each subject. The LAA-ACI captured the subject-specific LAA 3D geometry in terms of a single number. LAA tm varied significantly within a given LAA morphology as defined by the current subjectivemethod and it was not simply a reflection of LAA geometry/appearance. In addition, LAA-ACI and LAA tm varied significantly for a given CHA2DS2-VASc score, indicating that these two indices of stasis are not simply a reflection of the subjects’ clinical status. We conclude that LAA-ACI and LAA tm add independent information to the CHA2DS2-VASc score about stasis risk and thereby can potentially enhance its ability to stratify stroke risk in AF patients

Narrow QRS complex tachycardia with long RP-interval: what is the mechanism?

No anstrac

Oxygen Kinetics and Heart Rate Response during Early Recovery from Exercise in Patients with Heart Failure

Background. The purpose of this study was to assess the post-exercise O2 uptake and heart rate response in patients with heart failure (HF) in comparison to healthy individuals. Methods and Results. Exercise testing of all subjects was conducted according to the RITE-protocol. The study subjects were classified according to their peak oxygen uptake (peak VO2) in four groups: healthy individuals with a peak VO2 >22 mL/kg/min (group 1, : 50), and patients with HF and a peak VO2 of 18–22 mL/kg/min, (group 2, : 48), 14–18 mL/kg/min (group 3, : 57), and <14 mL/kg/min (group 4, : 31). Both peak VO2 and HR declined more slowly in the patients with HF than in the normal subjects. Recovery of VO2 and HR followed monoexponential kinetics in the early post-recovery phase. This enabled the determination of a time constant for both HR and VO2 (TC VO2 and TC HR). From group 1 to 4 there was a prolongation of the time constant for VO2 and HR: TC VO2 (group 1: 110±34, group 2: 197±43, group 3: 238±80, and group 4: 278±50 sec), and TC HR (group 1: 148±82, group 2: 290±65, group 3: 320±58, and group 4: 376±55 sec). Conclusion. The rate of decline of VO2 and HR in the early post-exercise phase is inversely related to the peak VO2. The time constant for oxygen uptake (TC VO2) and heart rate (TC HR) might prove a useful parameter for more precise monitoring and grading of HF

a comparison between rotational angiography and cardiac computed tomography.

Vorhofflimmern ist die häufigste anhaltende Rhythmusstörung und eine der häufigsten Ursachen für ambulante Arztbesuche und Krankenhausaufenthalte. Die hohe Morbidität sowie die steigende Inzidenz und Prävalenz im zunehmenden Alter sind bei einer alternden Bevölkerung von großer sozioökonomischer Bedeutung. Die Pulmonalvenenisolation (PVI) durch Katheterablation hat die Behandlung von Vorhofflimmern verbessert und sich in den letzten Jahren exponentiell verbreitet. Dieses Verfahren bleibt aber sehr anspruchsvoll und erfordert, außer der Röntgendurchleuchtung, eine dreidimensionale Darstellung des linken Vorhofs und der Pulmonalvenen. Verschiedene bildgebende Verfahren wie die Cardio-Computertomographie (Cardio-CT), die Kernspintomographie (MRT) oder das intraoperatives elektroanatomisches Mapping (EAM) sind hierzu zum Einsatz gekommen, bleiben aber zeitaufwendig und kostenintensiv. In der vorliegenden Arbeit wurde eine neuartige bildgebende Methode für die Pulmonalvenenisolation angewandt: die Rotations-Angiographie (RTA) und die daraus resultierende dreidimensionale Atriographie (3D-ATG). Ziel dieser Arbeit war die 3D-ATG mit der herkömmlichen Cardio-CT als Goldstandard im Hinblick auf Genauigkeit und Sicherheit zu vergleichen. Dazu wurden bei 101 konsekutiven Patienten mit symptomatischem, medikamentös refraktärem Vorhofflimmern, beide bildgebende Verfahren und eine PVI anhand der intraoperativen 3D-ATG durchgeführt. Die Abbildung der Pulmonalvenen und des linken Herzohrs mittels 3D-ATG war in den meisten Fällen qualitativ nützlich oder optimal. Ein Vergleich von linearen Messungen der Pulmonalvenen und des linken Vorhofs konnte keinen signifikanten Unterschied zwischen den zwei Methoden feststellen. Der weiterer Vergleich von volumetrischen Messungen zeigte ebenfalls gleiche Genauigkeit. Die Subanalyse der Patienten für die verschiedenen 3D-ATG-Protokolle, nämlich die RTA nach Adenosin-Gabe (Ad-RTA) oder die RTA mit schneller rechstventrikulärer Stimulation (VP-RTA), zeigte hohe Übereinstimmung zwischen Cardio-CT und 3D-ATG für jede einzelne Untergruppe. Es gibt jedoch einige Einschränkungen für die Anwendung jeder RTA-Methode, die vom Operateur berücksichtigt werden sollten; Ad-RTA sollte bei Patienten mit obstruktiver Lungenerkrankungund und VP-RTA bei Patienten mit schwergradiger koronarer Herzerkrankung oder Kontrastmittelkontraindikationen vermieden werden. Desweiteren hat sich gezeigt, dass die 3D-ATG zwar vergleichbare Abbildung in kürzerer Zeit und mit weniger Strahlenexposition als die Cardio-CT, unabhängig vom RTA-Protokoll liefert. Somit werden die Strahlenbelastung und das Risiko einer Krebserkrankung signifikant reduziert. Außerdem wird die 3D-ATG am Tag der Prozedur und nicht an einem präoperativen Tag durchgeführt, so dass der zusätzlicher Aufwand und die Beschäftigung von spezialisiertem Personal gespart werden. Die Nicht-Unterlegenheit der 3D-ATG im Vergleich zu Cardio-CT zusammen mit der niedrigeren Strahlendosis und dem geringeren Aufwand definieren die 3D-ATG als eine vernünftige Alternative zu Cardio-CT für die Führung der Pulmonalvenenisolation. Aufgrund dieser überzeugenden Resultate wurde in unserer Klinik die Cardio-CT Untersuchung aus dem Programm unserer Ablations-Verfahren genommen und die Pulmonalvenenisolation seitdem nur anhand der 3D-ATG durchgeführt.Atrial fibrillation is the most common sustained arrhythmia and a leading cause of both outpatient visits and hospitalizations. The high morbidity together with the increasing incidence and prevalence of an aging population are thus of great socio-economic importance. The pulmonary vein isolation (PVI) by catheter ablation has improved the treatment of atrial fibrillation and has been widely spread in the recent years. This method, however, remains very challenging and requires, in addition to X-ray, a three-dimensional representation of the left atrium (LA) and the pulmonary veins (PV). Various imaging techniques such as cardiac computed tomography (cardiac CT), magnetic resonance imaging (MRI) or intraoperative electrophysiological anatomical mapping (EAM) have been used for this purpose, but all these methods remain time-consuming and costly. In the present study patients were studied with a novel imaging method for the facilitation of pulmonary vein isolation; the rotational angiography (RTA) and the resulting three-dimensional atriography (3D-ATG). Aim of the study was to compare the 3D-ATG with the conventional cardiac CT, as a gold standard imaging technique, in terms of accuracy and safety. For this purpose 101 consecutive patients with symptomatic, medically refractory atrial fibrillation underwent both imaging modalities and a PVI using the intraoperative 3D-ATG. Imaging of the pulmonary veins and of the left atrial appendage in 3D-ATG was in most cases qualitatively useful or optimal. A comparison of linear measurements of the pulmonary veins and the left atrium did not show any significant difference between the two methods. A further comparison of volumetric measurements showed also a similar accuracy. Subanalysis of the different 3D-ATG-protocols, namely the RTA after adenosine administration (Ad-RTA) and the RTA with rapid right ventricular pacing (VP- RTA), showed high correlation between measurements for each sub-group. However there are some limitations to the application of each RTA method that should be considered by the operator; Ad-RTA should be avoided in patients with obstructive lung disease and VP-RTA should be avoided in patients with severe coronary artery disease or contrast agent contraindication. The study further showed that 3D-ATG provides similar imaging, in less time and with less radiation exposure than the cardio-CT, irrespective of the RTA protocol. Thus, the radiation exposure and the risk of cancer are significantly reduced. Furthermore, 3D-ATG is performed on the day of the procedure, and not on a pre-operative day, thus reducing the associated expenses of an additional appointment and the occupation of specialized personnel. The non-inferiority of 3D-ATG compared with cardio-CT together with reduced radiation dose and lower expenses, define 3D-ATG as a reasonable alternative to cardiac CT for the facilitation of pulmonary vein isolation. Based on these compelling results, cardiac CT was omitted from the workflow of ablation procedures in our clinic and since then, pulmonary vein isolation has been performed using only 3D-ATG imaging

Catheter ablation of atrial fibrillation: the association between atrial anatomy and clinical outcomes

Atrial fibrillation (AF) is the most common rhythm problem affecting millions of people worldwide. AF is associated with 5x higher stroke risk and often with distressing symptoms that significantly reduce life-quality. Due to an aging population, AF patients are expected to double in the next 30 years to >14 million in Europe alone. Thus, identification of surrogates that could improve AF treatment is very important. Catheter ablation of the left atrium (LA) can eliminate AF triggers and reduce AF burden. Anticoagulation can reduce the risk of thromboembolic events (TE). However, the relationship of LA anatomy with relevant AF outcomes has not been adequately examined yet. This thesis approaches the role of anatomy with novel geometrical indexes and examines the role of LA appendage (LAA) for TEs in patients with clinically low-risk, the characteristics of LA remodeling in different AF types and their association with ablation outcomes, diastolic dysfunction, plasma markers and low-voltage areas as surrogates of AF substrate. The results are relevant for future research especially for imaging-based prognostic models that will guide management of AF patients in the era of computational precision medicine