Proceedings of The Physiological Society

Europhysiology 2018 (London, UK) (2018) Proc Physiol Soc 41, PCA002

Poster Communications

Effect of Valsalva Maneuver on Ventricular Repolarization

O. Bhagat1, A. Singhal1, S. Deora2

1. Physiology, All India Institute of Medical Sciences, Jodhpur, India, Jodhpur, Rajasthan, India. 2. Cardiology, All India Insitute of Medical Sciences, Jodhpur, India, Jodhpur, India.

Introduction: Though Valsalva manoeuvre is well documented for its cardiovascular and autonomic responses (1) but little has been studied about its effect on ventricular repolarisation. Prolongation of ventricular repolarisation predisposes to arrhythmias (2). It causes the increase in intrathoracic pressure thereby compressing blood vessels and heart, which may lead to modulation of ventricular repolarisation. Therefore, we attempted to measure the effect of Valsalva manoeuvre on ventricular repolarisation. Method: We conducted the study after ethical approval from institutional ethics committee on ten male volunteers of 17-21 years of age. ECG and respiratory movements were recorded at baseline, during strain and after release, in Valsalva manoeuvre at maximal effort for 7 seconds. BIOPAC MP150 with BN-TX RSPEC 3.0 was used for acquisition and LabChart 5 software for analysis. We measured RR interval, QT interval, QTc, JT interval, Tpeak-end duration and Tpeak- end / QT interval ratio for baseline, phase II and phase IV of Valsalva manoeuvre. Results: Tpeak-end duration and Tpeak- end QT interval ratio, which is the index for transmural dispersion of ventricular repolarization (3), were increased more than double from 40 ± 0.01 ms and 0.14±0.01at baseline to 83±0.04 ms and 0.29 ± 0.11 respectively in phase II (strain phase) of Valsalva manoeuvre. These returned to near baseline values in phase IV. RR interval decreased (840 ± 0.08 to 643 ± 0.06) whereas QTc interval increased (314 ± 0.02 to 342 ± 0.0.05) in phase II of Valsalva manoeuvre (Table1). Conclusion: Ventricular repolarisation duration increases during phase II (continued strain) thus it may trigger arrhythmic episodes in susceptible individuals on performing Valsalva manoeuvre.

Where applicable, experiments conform with Society ethical requirements