The impact of Centruroides tecomanus scorpion venom on cardiac function in rats during early envenomation

Scorpion envenomation is a medical emergency that can produce severe cardiovascular complications . Centruroides tecomanus , an endemic scorpion species from western Mexico, is medically relevant, although its early cardiac effects remain poorly characterized. This study evaluated the initial cardiotoxic effects of C. tecomanus venom in Wistar rats using serial electrocardiographic recordings, algorithm-based ECG signal processing, histopathology, and serum biochemical markers. Fourteen rats were allocated to control and venom-treated groups (n = 7 per group). The experimental group received an intraperitoneal sublethal dose equivalent to one-third of the LD 50 . One-minute ECG recordings obtained at 5-min intervals during the first hour were analyzed using an enhanced computational algorithm for noise reduction, R-peak detection, R–R interval analysis, and characterization of cardiac conduction. Venom-treated animals showed a biphasic chronotropic response, with early tachycardia followed by progressive bradycardia, together with altered impulse generation, migratory atrial pacemaker activity, and atrioventricular conduction abnormalities. Histopathological analysis revealed increased inter-fiber separation and eosinophilic changes in the ventricular myocardium, without overt necrosis, whereas pulmonary architecture remained largely preserved. CK, CK-MB, and AST showed no significant changes at 8 h after envenomation, while LDH decreased significantly. These findings characterize the early temporal progression of C. tecomanus venom-associated cardiotoxicity, beginning with rhythm and atrioventricular conduction abnormalities and accompanied by mild myocardial inter-fiber separation, but without overt necrosis or a conventional serum enzyme pattern of myocardial injury.