COMPARISON OF MODIFIED CAROTID SINUS MASSAGE USING ULTRASONOGRAPHY WITH CONVENTIONAL CAROTID SINUS MASSAGE IN EMERGENCY DEPARTMENT

Abstract

Objectives: To compare the vagal response, measured by heart-rate reduction and R–R interval prolongation, produced by ultrasound-guided modified carotid sinus massage (CSM) versus conventional CSM in hemodynamically stable patients with acute supraventricular tachycardia (SVT) in the emergency department (ED). The study evaluated physiological response, not definitive clinical efficacy.

Methodology: This prospective, open-label, blinded-endpoint randomized controlled trial was conducted at Central Park Teaching Hospital, Lahore (January 03, 2026 to April 03, 2026; IRB No. CPMC/IRB-No/1541). Patients aged 35–75 years with narrow-QRS (<120 ms) tachycardia >150 bpm, adjudicated by a blinded cardiologist, were randomized 1:1 using computer-generated permuted blocks with sealed opaque envelopes to ultrasound-guided modified CSM (Group A, n=125) or conventional CSM (Group B, n=125). In Group A, a 7.5–12 MHz linear probe identified the right carotid bulb at maximum dilation for a targeted 10-second unilateral pressure; Group B received right-sided palpation-guided pressure for 10 seconds. One attempt per patient was permitted. Primary outcomes were heart-rate and R–R interval change on continuous Lead II ECG, which were adjudicated blinded to allocation.

Results: Groups were balanced at baseline. Ultrasound-guided modified CSM produced significantly greater heart-rate reduction (53.2 ± 17.1 vs 25.8 ± 13.9 bpm; mean difference 27.4, 95% CI 23.2 to 31.6; p < 0.001; Cohen's d = 1.78) and R–R interval prolongation (0.272 ± 0.118 vs 0.148 ± 0.092 s; mean difference 0.124, 95% CI 0.098 to 0.150; p < 0.001; d = 1.12). No adverse events occurred (95% CI 0–1.5%).

Conclusion: Ultrasound-guided modified CSM produces a significantly greater vagal response and appears safe. Because these are surrogate endpoints, clinical superiority (SVT termination, rescue therapy, recurrence) requires confirmation in adequately powered multicenter trials before routine ED adoption.