Sistolik

Sistolik, or systolic, refers to the phase of the cardiac cycle in which the ventricles contract, ejecting blood into the aorta and the pulmonary artery. In common clinical usage, systolic also describes systolic blood pressure, the peak arterial pressure reached during this contraction.

During systole the electrical activation of the heart leads to ventricular contraction, opening the semilunar valves and propelling blood into the systemic and pulmonary circulations. The duration of systole is approximately 0.25 to 0.30 seconds in a typical heart rate, forming roughly one third of an average 0.8-second cardiac cycle.

Systolic blood pressure is the maximum arterial pressure observed during systole, while diastolic pressure is the minimum during diastole. In adults, normal systolic values generally range from about 90 to 120 mmHg, with diastolic values around 60 to 80 mmHg. Readings above 130 mmHg for systolic pressure are often categorized as elevated or hypertensive according to different guidelines.

Clinical significance related to systolic pressure includes the impact of elevated systolic blood pressure on cardiovascular risk. Isolated systolic hypertension, common in older individuals due to arterial stiffness, increases the risk of heart disease and stroke. Very low systolic pressure can indicate shock or reduced cardiac output. The pulse pressure, the difference between systolic and diastolic values, provides additional information about arterial health.

Measurement of systolic pressure is typically done noninvasively with cuff-based devices using auscultation or oscillometry, though invasive arterial monitoring is used in hospital settings. Echocardiography can assess systolic function beyond blood pressure readings. The term derives from Greek, with “systole” meaning contraction.