The sympathetic contributions to the cardiac plexus

Cardiac sympathetic denervation for intractable angina pectoris in patients unsuitable for conventional revascularization is currently gaining popularity since this procedure may be performed via minimally invasive surgery. A thorough understanding of cardiac innervation and its variations is crucial to successfully effect cardiac denervation. This study aimed to demonstrate the cervical and thoracic sympathetic contributions to the cardiac plexus. The cervical and thoracic sympathetic trunks in 21 fetuses and eight adults were micro-dissected bilaterally and documented ( n=58 sides). The superior cervical cardiac ramus originated from the superior cervical ganglion (present in all specimens) in 53% of cases. The middle cervical ganglion (incidence 81%) gave rise to the middle cervical cardiac ramus in 88% of cases. The cervico-thoracic ganglion (incidence 85%) gave the cervico-thoracic cardiac ramus in 84%. In the thoracic region, four cardiac rami arose from the T2-T6 segment of the thoracic sympathetic trunk. All cervical and thoracic cardiac rami were traced consistently to the deep cardiac plexus. Khogali et al.'s (1999) success of limited T2-T4 sympathectomy in relieving pain at rest of patients with intractable angina pectoris appears to indicate that a significant afferent pain pathway from the heart is selectively interrupted. The variability in pattern of the cervical ganglia, cardiac rami and cervical contributions to the cardiac plexus does not appear to affect the outcome of limited sympathectomy. The complexity of cardiac pain pathways is not fully understood. The study is continuing and attempts to contribute to defining these cardiac neuronal pathways.