Selective ablation of the ligament of Marshall reduces ischemia and reperfusion-induced ventricular arrhythmias

Abstract

Cardiac sympathetic tone overdrive is a key mechanism of arrhythmia. Cardiac sympathetic nerves denervation, such as LSG ablation or renal sympathetic denervation, suppressed both the prevalence of VAs and the incidence of SCD. Accumulating evidence demonstrates the ligament of Marshall (LOM) is a key component of the sympathetic conduit between the left stellate ganglion (LSG) and the ventricles. The present study aimed to investigate the roles of the distal segment of LOM (LOMLSPV) denervation in ischemia and reperfusion (IR)-induced VAs, and compared that LSG denervation. Thirty-three canines were randomly divided into group 1 (IR group, n = 11), group 2 (LOMLSPV Denervation + IR, n = 9), and group 3 (LSG Denervation + IR, n = 13). Hematoxylin-Eosin (HE) and Immunohistochemistry staining revealed that LOMLSPV contained bundles of sympathetic but not parasympathetic nerves. IR increased the cardiac sympathetic tone [serum concentrations of noradrenaline (NE) and epinephrine (E)] and induced the prevalence of VAs [ventricular premature beat (VPB), salvo of VPB, ventricular tachycardia (VT), VT duration (VTD) and ventricular fibrillation (VF)]. Both LOMLSPV denervation and LSG denervation could reduce the cardiac sympathetic tone in Baseline (BS) [heart rate variability (HRV)]. Compared with group 1, LOMLSPV denervation and LSG denervation similarly reduced sympathetic tone [NE (1.39±0.068 ng/ml in group 2, 1.29±0.081 ng/ml in group 3 vs 2.32±0.17 ng/ml in group 1, P<0.05) and E (114.64±9.22 pg/ml in group 2, 112.60±9.69 pg/ml in group 3 vs 166.18±15.78 pg/ml in group 1, P<0.05),] and VAs [VT (0±3.00 in group 2, 0±1.75 in group 3 vs 8.00±11.00 in group 1, P<0.05) and VTD (0 ± 4 s in group 2, 0±0.88s in group 3 vs 10.0 ± 22.00s in group 1, P<0.05)] after 2h reperfusion. These findings indicated LOMLSPV denervation reduced the prevalence of VT by suppressing SNS activity. These effects are comparable to those of LSG denervation. In myocardial IR, the anti-arrhythmic effects of LOMLSPV Denervation may be related to the inhibition of the expression of NE and E.

Fig 1. Experimental protocols.

IR: ischemia and reperfusion; NE: noradrenaline; E: epinephrine; HRV: heart rate variability; LSGD: left stellate ganglion denervation; LOM_LSPVD: LOM_LSPV denervation; LAD: left anterior descending coronary artery; Vas: ventricular arrhythmias; R2 h: reperfusion for 2 h.

Fig 2. The potential and anatomy position of LOM.

(A) The potential of LOM from its proximal to its distal portion. (B) The potential of the distal portion of the LOM dismissed. (C) The LOM originates from the coronary sinus and ends in the pericardium near the LSPV. (D) The LSG sends out a cluster of fibers that end in the posterior cervical ganglion, which sends out a bundle of fibers that innervate the distal part of the LOM. LOM: the ligament of Marshall; LSPV, LIPV: left superior, left inferior pulmonary vein; PA: pulmonary artery; LAA: left atrial appendage.

Fig 3. The LOM_LSPV contains abundant sympathetic but not parasympathetic nerves.

(A) HE staining; (B) positive TH staining; (C) negative CHAT staining; (D) CHAT positive control.

Fig 4. Both LOM_LSPVD and LSGD reduced the cardiac sympathetic tone (LF, LF/HF and iNE) but not parasympathetic tone (HF).

(A) LOM_LSPVD and LSGD exhibit reduced LF and LF/HF ratios but exhibit no change in HF in BS. (B) LOM_LSPVD and LSGD exhibit reduced serum E concentrations after 2 h of reperfusion. (C) LOM_LSPVD and LSGD exhibit reduced serum NE concentrations after 2 h of reperfusion (as above). (D) After 2 h of reperfusion, serum NE concentrations were significantly higher in group 1. (E) After 2 h of reperfusion, serum E concentrations were significantly higher in group 1 (n = 7). BS: baseline state. D-30 min: 45 min after the pericardium was cut open in group 1 or 30 min after sympathetic nerve denervation, R2 h: 2 h after reperfusion, LF: low frequency, HF: high frequency; D-LF, D-HF and D-LF/HF: the values for LF, HF and the LF/HF ratio at 45 min after the pericardium was cut open in group 1 or 30 min after sympathetic nerve denervation in group 2 and group 3; * P<0.05, ** P<0.001. Group 1: n = 11 before reperfusion, n = 7 after reperfusion; Group 2: n = 9 before reperfusion, n = 7 after reperfusion; Group 3: n = 13 before reperfusion, n = 12 after reperfusion.

Fig 5. LOM_LSPVD and LSGD similarly suppressed the prevalence of VT and VTD.

(A) VPB, Salvo of VPB, VT and VF recording segments; (B) LOM_LSPV denervation and LSG denervation similarly reduced the prevalences of VT and VTD but not VPB or Salvo of VPB; (C) VF showed a decreasing trend in the group 2 and Group 3; VPB: ventricular premature beat, Salvo of VPB: Salvo ventricular premature beat, VT: ventricular tachycardia; VTD: the duration of VT, VF: ventricular fibrillation. * P<0.05, ** P<0.001. Group 1: n = 7; Group 2: n = 7; Group 3: n = 12.