DTA

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Tesi etd-11102021-191652

Type of thesis
Corsi integrativi
Author
LEALI, MARCO
URN
etd-11102021-191652
Title
Cardiac effects of left-sided vagotomy in minipigs: preliminary data and comparison with vagal nerve cuff recordings
Structure
Cl. Sc. Sperimentali - Medicina
Course
SCIENZE MEDICHE - SCIENZE MEDICHE
Committee
relatore Prof. LIONETTI, VINCENZO
Membro Prof. EMDIN, MICHELE
Membro Dott.ssa CASIERI, VALENTINA
Membro Prof. GIANNONI, ALBERTO
Membro Prof.ssa ANGELONI, DEBORA
Membro Prof. PASSINO, CLAUDIO
Membro Prof. RECCHIA, FABIO ANASTASIO
Membro Prof. COCEANI, FLAVIO
Keywords
  • cuff
  • MUA
  • multiunit activity
  • reflex
  • spike sorting
  • thoracic
  • unilateral
  • vagotomy
  • vagus
Exam session start date
20/12/2021;
Availability
parziale
Abstract
Background: While the correlation between higher parasympathetic tone and exercise has long been known, only recently we have been provided with proof of a causal relationship between vagal activity and exercise capacity. It is therefore of interest to develop therapeutic interventions facilitating the restoration of functional vagal innervation in those conditions where it is interrupted, such as in cardiac transplant patients. To pursue this objective, implantable vagal neuroprostheses able to detect cardiac vagal activity are being studied.<br>Objective: Within the context of a study on a vagal neuroprosthesis, to research whether neural signals recorded from implantable multipolar cuff-electrodes may offer meaningful information on cardiac vagal control.<br>Methods: After sternotomy, six minipigs were implanted with cuff-electrodes on both thoracic vagal nerves and underwent left-sided thoracic vagotomy. Peripheral arterial blood pressure and surface electrocardiograms were recorded during the procedure. Heart rate variability indices, electrocardiographic intervals and a recently validated correlate of cardiac contractility (arterial dP/dt max) were used to assess cardiac function. Multi-unit activity (MUA) detection and wavelet denoising plus spike sorting were performed on vagal cuff recordings.<br>Results: After vagotomy, no significant trends in heart rate and systolic arterial pressure were observed, but higher short-term heart rate variability (root mean square of successive differences [RMSSD]) (p=0.118), and longer corrected QT intervals (p=0.319) were seen. In contrast, cardiac contractility, as measured by arterial dP/dt max, seemed to be increased (p=0.353). PR and QRS intervals and mean and systolic blood pressure did not show any apparent trend. Multi-unit activity from cuff-electrodes on both the right and the left vagus nerve decreased (p=0.06) with vagotomy, while compound action potentials (CAP) from spike sorting were inconsistent among electrodes within the same cuff.<br>Conclusion: Unexpectedly, we may have reported an acute reflex response of the right vagus after left-sided vagotomy in minipigs. The increased contractility after unilateral vagotomy might be effectively counterbalanced by an increased vagal drive on the sinoatrial node, without significant changes in blood pressure over our sample. Unfortunately, our results indicate that multi-unit activity from thoracic vagal cuff recordings may be unsuitable for detecting changes in vagal activity of cardiac origin and spike sorting did not seem to improve our specificity.
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