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Systole (/ ˈ s ɪ s t əl i / SIST-ə-lee) is the part of the cardiac cycle during which some chambers of the heart contract after refilling with blood. [1] Its contrasting phase is diastole , the relaxed phase of the cardiac cycle when the chambers of the heart are refilling with blood.
Cardiac diastole is the period of the cardiac cycle when, after contraction, the heart relaxes and expands while refilling with blood returning from the circulatory system. [ 1 ] [ 2 ] Both atrioventricular (AV) valves open to facilitate the 'unpressurized' flow of blood directly through the atria into both ventricles, where it is collected for ...
A Wiggers diagram, named after its developer, Carl Wiggers, is a unique diagram that has been used in teaching cardiac physiology for more than a century. [1] [2] In the Wiggers diagram, the X-axis is used to plot time subdivided into the cardiac phases, while the Y-axis typically contains the following on a single grid: Blood pressure. Aortic ...
The period of time that begins with contraction of the atria and ends with ventricular relaxation is known as the cardiac cycle. The period of contraction that the heart undergoes while it pumps blood into circulation is called systole. The period of relaxation that occurs as the chambers fill with blood is called diastole.
Wiggers diagram of the cardiac cycle, with isometric contraction marked at upper left. In cardiac physiology, isometric contraction is an event occurring in early systole during which the ventricles contract with no corresponding volume change (isometrically). This short-lasting portion of the cardiac cycle takes place while all heart valves are
These compressions serve two goals. First, the compressions circulate blood to the brain and other tissues which helps reduce their ischemia and attenuates later post-cardiac arrest syndrome. This goal is accomplished during the compression phase of the CPR cycle as it creates systole-like hemodynamics .
The sound occurs just after atrial contraction at the end of diastole and immediately before S1, producing a rhythm sometimes referred to as the "Tennessee" gallop where S4 represents the "Ten-" syllable. [2] It is best heard at the cardiac apex with the patient in the left lateral decubitus position and holding their breath.
Blood velocities in arteries are higher during systole than during diastole. One parameter to quantify this difference is the pulsatility index (PI), which is equal to the difference between the peak systolic velocity and the minimum diastolic velocity divided by the mean velocity during the cardiac cycle. This value decreases with distance ...