Background and Objectives:The Valsalva maneuver (VM) is the most effective measure that can be carried out to treat supraventricular tachycardia (SVT). Our objective was to compare the efficacy of postural modified VM with 20 ml syringe to standard VM for the emergency treatment of SVT.Methods:This randomized control trial study was conducted at the Accident and Emergency Department, Pakistan ordinance factories hospital, Wah Cantt from July 2019 to September 2020. In the standard Valsalva group, fifty patients were placed at an angle of 45 with continuous monitoring of vitals and electrocardiogram. Patients blew into a 20ml syringe to generate 40 mmHg pressure for 15 seconds and remained in the same position for 45 seconds before a reassessment of cardiac rhythm at one-minute and three-minute intervals. In the modified Valsalva group same procedure was repeated with the other fifty patients, but immediately at the end of the strain, they were laid flat with their legs raised to 45° for 15 seconds. Participants returned to semi-recumbent position and cardiac rhythm was reassessed after 45 seconds and then at one and three minutes.Results:In the standard Valsalva maneuver (SVM)20.0% of participants versus 58% of participants in the modified Valsalva maneuvers group(MVM) reverted to sinus rhythm at one min (odds ratio or 5.52, 95% CI 2.26-13.47; p<0.001) and time of stay in the emergency room was (odds ratio or 2.39, 95% CI 1.45- 3.93; p<0.0001).Conclusion:Modified Valsalva by using a wide-bore syringe is more effective method than standard Valsalva in terminating SVT.