Annual deaths from tornadoes, earthquakes and floods together total fewer than 200. The most deadly heat wave in recent years occurred in Chicago over a week in July 1995, when temperatures hovered around 100 degrees.
Cardiac Cycle: 1st Systole Phase. During the systole phase, the right ventricle receives impulses from the Purkinje fibers and contracts. The atrioventricular valves close and the semilunar valves open. The de-oxygenated blood is pumped into the pulmonary artery.
Presence of echo-. free space between the two layers of pericardium throughout. the cardiac cycle confirms the diagnosis. 2 Normally also, there. is small amount of fluid (5-15 ml) in the pericardial sac. However, in normal persons, a clear space between the two. layers of pericardium can be seen only during systole.