Which one of the following findings is indicative of compromised LV performance?
LV systole has the phases of pre-ejection isovolumic contraction and ejection. If total systole duration remains normal, but isovolumic contraction duration increases, it would mean the ejection time has reduced. It is indicative of a compromised LV performance. Exact measurement of the duration of isovolumetric ventricular contraction is done by using the following parameters: Total electromechanical systole (QS2), Pre-ejection period (PEP), and LV ejection time (LVET) These can be measured by recording: ECG ~ for the QRS complex; the Q wave indicates sta of ventricular depolarization or electrical systole, Phonocardiogram ~ to record hea sounds; 2nd hea sound will mark the end of systole, and Carotid pulse ~ to record LVET, which is from the beginning of carotid pressure rise to the dicrotic notch. QS2 = electromechanical systole; from the onset of QRS complex on ECG to the closure of semilunar valves - dicrotic notch on carotid pulse. PEP is calculated as ~ (Total electromechanical systole) - (ejection time) PEP = (QS2) - (LVET) PEP represents the electrical depolarization and isovolumic contraction of LV, that occur before the systolic ejection. The ratio PEP/LVET is normally about 0.35. If QS2 is normal but PEP/LVET ratio has increased, it means pre-ejection period has increased and the ejection time is reduced; it indicates a compromised LV performance.
increased left ventricular ejection time (LVET); normal pre-ejection period (PEP) and normal QS2 duration
PEP/LVET ratio = 0.35; shoened QS2 duration
PEP/LVET ratio > 0.35; no change in QS2duration
Reduction in PEP, LVET, and QS2 duration
Cardiac Output