R-wave Amplitude in Lead II of an Electrocardiograph Correlates with Central Hypovolemia in Human Beings

Objectives Previous animal and human experiments have suggested that reduction in central blood volume either increases or decreases the amplitude of R waves in various electrocardiograph ECG leads depending on underlying pathophysiology. In this investigation, we used graded central hypovolemia in adult volunteer subjects to test the hypothesis that moderate reductions in central blood volume increases R-wave amplitude in lead II of an ECG. Methods A four-lead ECG tracing, heart rate HR, estimated stroke volume SV, systolic blood pressure, diastolic blood pressure, and mean arterial pressure were measured during baseline supine rest and during progressive reductions of central blood volume to an estimated volume loss of greater than 1,000 mL with application of lower-body negative pressure LBNP in 13 healthy human volunteer subjects. Results Lower-body negative pressure resulted in a significant progressive reduction in central blood volume, as indicated by a maximal decrease of 65 in SV and maximal elevation of 56 in HR from baseline to 60 mm Hg LBNP. R-wave amplitude increased p less than 0.0001 linearly with progressive LBNP. The amalgamated correlation R2 between average stroke volume and average R-wave amplitude at each LBNP stage was -0.989. Conclusions These results support our hypothesis that reduction of central blood volume in human beings is associated with increased R-wave amplification in lead II of an ECG.