IMED3001 Study Guide - Final Guide: The Terminal, Blood Pressure, Cardiac Output
20 Dec 2020
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Document Summary
The same phenomenon occurs in the intact ventricle, but resting muscle tension cannot be readily measured in the intact ventricle and it varies with the location in the heart. In the intact ventricle, preload is quantified as the ventricular volume prior to contraction: the end-diastolic volume (edv). Acute changes in preload in an individual subject are best characterized by changes in edv. The strength of ventricular contraction is greater when the preload is higher. We will focus on filling of the heart during diastole. Blood flows into the ventricle when the heart is relaxed, so the volume increases along the diastolic (passive) pressure-volume curve. The more blood flows into the heart, the higher the pressure even before contraction. Diastole ends when the heart begins to contract, and the edv and edp (end-diastolic pressure) are defined by this point. Preload variations are probably the most important determinants of cardiac output under normal circumstances.
