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Epicardial injection of nanoformulated calcium into cardiac ganglionic plexi suppresses autonomic nerve activity and postoperative atrial fibrillation.

ABSTRACT: BACKGROUND:Imbalanced activation of the cardiac autonomic nervous system triggers postoperative atrial fibrillation (POAF). Neuronal calcium overload induces apoptosis. We hypothesize that epicardial injection of timed-release nanoformulated CaCl2 (nCaCl2) into left atrial ganglionic plexi (GP) modulates autonomic function and suppresses POAF. OBJECTIVE:The purpose of this study was to determine whether nCaCl2 GP therapy suppresses POAF. METHODS:We used a novel canine model of POAF with implanted radiotelemetry to record nerve activity (NA) from the left stellate ganglion (SNA), left cardiac vagus nerve, and GP. At week 3, nCaCl2 (n = 7) or vehicle control (sham; n = 3) was injected into left pulmonary vein GP (LGP), followed by right pulmonary vein GP at week 4. Atrial effective refractory period (AERP) and atrial fibrillation vulnerability (AFV) were assessed in vivo. Resting and exercise NA and heart rate (HR) were assessed before and after LGP treatment. RESULTS:AERP decreased (P < .0001) and AFV increased (P = .008) at week 3 vs baseline. However, nCaCl2-LGP treatment reversed these changes and restored them to baseline after 1 week (P = .04). Subsequent nCaCl2-right pulmonary vein GP treatment further reduced AFV (P = .03). In contrast, AFV increased (P = .001) and AERP remained decreased (P = .01) 1 week after sham-LGP treatment vs baseline. nCaCl2-LGP treatment reduced NA from GP (P < .02) and NA from the left cardiac vagus nerve (P < .05) and increased SNA (P < .02). Despite increased SNA, HR was decreased (P < .01) with loss of HR-SNA correlation (R = 0.62). After sham-LGP treatment, NA was unchanged and HR-SNA remained correlated (R = 0.95). Histology confirmed nCaCl2-GP colocalization, apoptosis, and loss of immunoreactivity in nCaCl2-treated somas. CONCLUSION:Epicardial injection of nCaCl2 into left atrial GP induced neuroapoptosis and modulated autonomic function. This reversed a postoperative reduction in AERP and suppressed POAF.

SUBMITTER: O'Quinn MP

PROVIDER: S-EPMC6446939 | biostudies-literature | 2019 Apr

REPOSITORIES: biostudies-literature

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Epicardial injection of nanoformulated calcium into cardiac ganglionic plexi suppresses autonomic nerve activity and postoperative atrial fibrillation.

O'Quinn Michael P MP Dormer Kenneth J KJ Huizar Jose F JF Nguyen Kytai T KT Kaszala Karoly K Sima Adam A Ellenbogen Kenneth A KA Tan Alex Y AY

Heart rhythm 20190401 4

<h4>Background</h4>Imbalanced activation of the cardiac autonomic nervous system triggers postoperative atrial fibrillation (POAF). Neuronal calcium overload induces apoptosis. We hypothesize that epicardial injection of timed-release nanoformulated CaCl<sub>2</sub> (nCaCl<sub>2</sub>) into left atrial ganglionic plexi (GP) modulates autonomic function and suppresses POAF.<h4>Objective</h4>The purpose of this study was to determine whether nCaCl<sub>2</sub> GP therapy suppresses POAF.<h4>Methods ...[more]

PMID: 30929671

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Project description:Background The autonomic nervous system response to apnea and its mechanistic connection to atrial fibrillation (AF) are unclear. We hypothesize that sensory neurons within the ganglionated plexi (GP) play a role. We aimed to delineate the autonomic response to apnea and to test the effects of ablation of cardiac sensory neurons with resiniferatoxin (RTX), a neurotoxic TRPV1 (transient receptor potential vanilloid 1) agonist. Methods Sixteen dogs were anesthetized and ventilated. Apnea was induced by stopping ventilation until oxygen saturations decreased to 80%. Nerve recordings from bilateral vagal nerves, left stellate ganglion, and anterior right GP were obtained before and during apnea, before and after RTX injection in the anterior right GP (protocol 1, n=7). Atrial effective refractory period and AF inducibility on single extrastimulation were assessed before and during apnea, and before and after intrapericardial RTX administration (protocol 2, n=9). GPs underwent immunohistochemical staining for TRPV1. Results Apnea increased anterior right GP activity, followed by clustered crescendo vagal bursts synchronized with heart rate and blood pressure oscillations. On further oxygen desaturation, a tonic increase in stellate ganglion activity and blood pressure ensued. Apnea-induced effective refractory period shortening from 110.20±31.3 ms to 90.6±29.1 ms ( P<0.001), and AF induction in 9/9 dogs versus 0/9 at baseline. After RTX administration, increases in GP and stellate ganglion activity and blood pressure during apnea were abolished, effective refractory period increased to 126.7±26.9 ms ( P=0.0001), and AF was not induced. Vagal bursts remained unchanged. GP cells showed cytoplasmic microvacuolization and apoptosis. Conclusions Apnea increases GP activity, followed by vagal bursts and tonic stellate ganglion firing. RTX decreases sympathetic and GP nerve activity, abolishes apnea's electrophysiological response, and AF inducibility. Sensory neurons play a role in apnea-induced AF.

Dataset Information

Epicardial injection of nanoformulated calcium into cardiac ganglionic plexi suppresses autonomic nerve activity and postoperative atrial fibrillation.

Publications

Epicardial injection of nanoformulated calcium into cardiac ganglionic plexi suppresses autonomic nerve activity and postoperative atrial fibrillation.

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