The study by Weissler, Harris, and Schoenfeld investigates the systolic time intervals in patients with heart failure, comparing them to those in normal subjects. The researchers used simultaneous recordings of the electrocardiogram (ECG), phonocardiogram, and carotid arterial pulse to measure the duration of systolic phases. They found that in heart failure patients, the pre-ejection period (PEP) was prolonged, while the left ventricular ejection time (LVET) was shortened, with total electromechanical systole remaining relatively unchanged. Both components of the PEP, the Q-T interval and isovolumic contraction time, were prolonged. These changes were well-correlated with reduced stroke volume and cardiac output, and were independently influenced by high arterial pressure. The study suggests that a defect in the mechanical performance of the heart is responsible for these abnormalities in systolic time intervals in heart failure. The findings are consistent with previous experimental studies and highlight the importance of systolic time intervals as measures of ventricular performance.The study by Weissler, Harris, and Schoenfeld investigates the systolic time intervals in patients with heart failure, comparing them to those in normal subjects. The researchers used simultaneous recordings of the electrocardiogram (ECG), phonocardiogram, and carotid arterial pulse to measure the duration of systolic phases. They found that in heart failure patients, the pre-ejection period (PEP) was prolonged, while the left ventricular ejection time (LVET) was shortened, with total electromechanical systole remaining relatively unchanged. Both components of the PEP, the Q-T interval and isovolumic contraction time, were prolonged. These changes were well-correlated with reduced stroke volume and cardiac output, and were independently influenced by high arterial pressure. The study suggests that a defect in the mechanical performance of the heart is responsible for these abnormalities in systolic time intervals in heart failure. The findings are consistent with previous experimental studies and highlight the importance of systolic time intervals as measures of ventricular performance.