Four spiroalkaloids, including a new compound shensongine A (1), were isolated from the anti-arrhythmic TCM formula Shensong Yangxin capsule. Their structures were determined on the basis of spectroscopic analysis. Compounds 1 and 3 displayed cardiovascular activities by shortened APD in rat myocardial cells. These compounds were possibly generated from precursors in different composed herbal medicines during the processing of the TCM formula. © 2015 Taylor & Francis.