NREMT Advanced EMT Practice Test #3

Answer - C - Extreme tachycardia can cause the diastole phase of the heart to become extremely short. The heart uses the diastole phase for filling, which in turn provides the preload for the ventricles. In situations of extreme tachycardia, the diastolic period is so short that there is ineffective filling, which subsequently drops ventricular stroke volume. The increase heart rate will increase oxygen requirements of the heart and diminish coronary artery perfusion since they are perfused during the diastolic phase.