Which one of the following findings is indicative of compromised LV performance?
Correct Answer: PEP/LVET ratio > 0.35; no change in QS2duration
Description: 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.
Category:
Physiology
Get More
Subject Mock Tests
Practice with over 200,000 questions from various medical subjects and improve your knowledge.
Attempt a mock test nowMock Exam
Take an exam with 100 random questions selected from all subjects to test your knowledge.
Coming SoonGet More
Subject Mock Tests
Try practicing mock tests with over 200,000 questions from various medical subjects.
Attempt a mock test now