Postoperatives Vorhofflimmern – eine klinische und experimentelle Risikoanalyse
by Judith Gronwald
Date of Examination:2023-06-01
Date of issue:2023-05-24
Advisor:Prof. Dr. Niels Voigt
Referee:Prof. Dr. Niels Voigt
Referee:Prof. Dr. Rolf Wachter
Sponsor:Deutsche Herzstiftung
Persistent Address:
http://dx.doi.org/10.53846/goediss-9897
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Abstract
English
Postoperative atrial fibrillation (poAF) is one of the most common complications after cardiac surgery and is associated with increased mortality and morbidity for the patients affected. Since the interplay of clinical and electrophysiological risk factors is not yet fully understood, both were investigated in detail in the present study and combined in a prediction score. First, atrial function was assessed using strain analysis, a technique that can measure the deformation of the atrial wall on the basis of echocardiographic images and visualise it over the course of a cardiac cycle. Significantly lower strain parameters were observed in the poAF group compared to patients from the sinus rhythm (SR) group which can be associated, among other things, with reduced tissue contractility. Overall, the strain analysis thus already gives an indication preoperatively whether a patient has an increased risk of developing poAF. Furthermore, human atrial tissue from patients undergoing cardiac surgery was analysed for poAF-specific differences at the cellular level. Using sharp microelectrodes, action potentials (AP) of single cells could be derived from trabeculae previously isolated from the tissue. The measured results were retrospectively assigned to the rhythm groups SR, poAF and chronic atrial fibrillation. Changes in AP amplitude and AP duration, that are consistent with previously described ion channel changes in terms of remodelling, could be found. These findings can be understood as part of a pre-existing arrhythmogenic substrate. In a next step, two score models for risk stratification of developing poAF were created from the collected clinical and experimental data using various statistical methods. The score model consisting of six clinical parameters showed a similar predictive performance as previously published clinical scores. Subsequently, a parameter from previously performed cellular measurements (the calcium transient amplitude) was added to the score. The inclusion of this factor, which is known to be involved in the genesis of poAF, led to a significant improvement in the predictive performance of the score model. Overall, the results of the risk factor analysis were consistent with the current understanding of the pathogenesis of poAF. In summary, this work contributes to a better understanding of both clinical and electrophysiological risk factors for the development of poAF and the use of the score can lead to an improved patient outcome through individualised medical care.
Keywords: atrial fibrillation; postoperative atrial fibrillation; score; atrial strain; sharp microelectrode; action potential
Schlagwörter: postoperatives Vorhofflimmern; Risikoscore; atrialer Strain; Aktionspotential; Vorhofflimmern