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Background: The sympathetic nervous system is thought to play a role in the genesis of ventricular tachyarrhythmias (VT). Left and added right cardiac sympathectomy have been shown to reduce the burden of arrhythmias in the setting of a VT storm. However, the contribution of the right stellate ganglion (RSG) and the left stellate ganglion (LSG) to the innervation of the anterior left ventricular (LV) wall is not well understood.Objective: To evaluate the innervation of the anterior LV wall by the LSG and the RSG.Methods: The heart and stellate ganglia were exposed via sternotomy in pigs with normal hearts (n = 8). A 20-electrode catheter was placed on the anterior LV wall to record activation recovery interval (ARI), a surrogate measure of action potential duration. A microdialysis catheter was inserted in a similar location to sample interstitial norepinephrine (NE) content. ARI and NE measurements were recorded at baseline and during LSG and RSG stimulation.Results: LSG stimulation shortened ARI by 17.1% ± 10.5% (mean ± standard error), while RSG stimulation shortened ARI by 42.1% ± 15.7%, P = .04 (LSG vs RSG). LSG stimulation increased interstitial NE levels by 200% ± 65%, while RSG stimulation increased the NE content by 260% ± 40% (P = .012). LSG stimulation increased dispersion in ARI from 376.0 ± 83.7 ms(2) to 1242.5 ± 566 ms(2) (P = .03) and caused ventricular fibrillation in 2 pigs. During RSG stimulation, dispersion increased from 419 ± 65.8 to 474.8 ± 81 ms(2) (P = .4).Conclusions: Both the LSG and the RSG provide significant innervation to the anterior LV wall as demonstrated by both ARI shortening and NE concentrations. LSG stimulation significantly increases ARI dispersion. This study provides mechanistic insight into the beneficial effects of left sympathectomy and the additional role of right sympathectomy in reducing arrhythmias in patients with anterior myocardial scars and VT storm. [ABSTRACT FROM AUTHOR]

Background: The presence of epicardial fat can confound the quantification of scar during transpericardial electroanatomic mapping. The electrogram (EGM) characteristics of epicardial fat have not been systematically compared with infarct scar using gross and histopathological analysis as a gold standard.Objective: The purpose of this study was to compare the EGM characteristics of epicardial fat with infarct scar.Methods: A closed-chest infarction was created in 40-50 kg pigs by occlusion of the circumflex artery for 150 minutes using an angioplasty balloon. This artery was chosen to minimize any potential overlap of epicardial fat with infarct and to spare any septal involvement. After 4-12 weeks of infarct healing, epicardial mapping was performed. EGMs in low-voltage regions (<1.5 mV) were analyzed, and bipolar amplitude, duration, number of deflections, and the presence of late potentials were recorded. Statistical analysis was performed using unpaired t-test and chi(2) analysis. Gross and histopathological examination was used to confirm areas of fat and infarct scar.Results: Seven porcine hearts were analyzed after high-density epicardial mapping (364 +/- 92 points) was performed 48 +/- 19 days after infarction. The mean bipolar EGM amplitude was similar in fat and scar (0.77 +/- 0.34 vs. 0.75 +/- 0.38 mV; P = not significant). The mean EGM duration was longer in scar than in fat (68.8 +/- 18.9 vs. 50.1 +/- 11.6 ms; P <.0001) and exhibited more fractionation (8.5 +/- 3.1 vs. 4.7 +/- 1.8 deflections; P <.0001). The presence of late potentials was 99% specific for scar. Further, areas of fat >4 mm in thickness registered low-voltage bipolar EGMs.Conclusion: Scar from healed myocardial infarction exhibits more fractionation and longer EGM duration when compared with fat. Late potentials are highly specific for locating infarct scars. [ABSTRACT FROM AUTHOR]