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Hyperdynamic circulation is abnormally increased circulatory volume. Systemic vasodilation and the associated decrease in peripheral vascular resistance results in decreased pulmonary capillary wedge pressure and decreased blood pressure, presenting usually with a collapsing pulse, but sometimes a bounding pulse.
Cardiac output is defined as the amount of blood pumped through the heart over 1 minute, in units of liters per minute, equal to heart rate multiplied by stroke volume. [4] It is directly related to heart rate, myocardial contractility, and preload, and inversely related with afterload. [4]
Pressure overload may affect any of the four chambers of the heart, though the term is most commonly applied to one of the two ventricles. Chronic pressure overload leads to concentric hypertrophy of the cardiac muscle, which can in turn lead to heart failure , myocardial ischaemia or, in extreme cases, outflow obstruction.
A blood volume increase would cause a shift along the line to the right, which increases left ventricular end diastolic volume (x axis), and therefore also increases stroke volume (y axis). The Frank–Starling law of the heart (also known as Starling's law and the Frank–Starling mechanism ) represents the relationship between stroke volume ...
Beyond this, there is volume overload, and stroke volume is diminished. Volume overload refers to the state of one of the chambers of the heart in which too large a volume of blood exists within it for it to function efficiently. Ventricular volume overload is approximately equivalent to an excessively high preload. It is a cause of cardiac ...
An increase in sympathetic stimulation to the heart increases contractility and heart rate. An increase in contractility tends to increase stroke volume and thus a secondary increase in preload. An increase in preload results in an increased force of contraction by Starling's law of the heart; this does not require a change in contractility.
Although the exact cause is not known, it is suspected that microgravity-induced fluid shift towards the head and comparable physiological changes play a significant role in these changes. [6] Other contributing factors may include pockets of increased carbon dioxide (CO 2) and an increase in sodium intake.
Intraocular pressure laws follow fundamentally from physics. Any kinds of intraocular surgery should be done by considering the intraocular pressure fluctuation. Sudden increase of intraocular pressure can lead to intraocular micro barotrauma and cause ischemic effects and mechanical stress to retinal nerve fiber layer. Sudden intraocular ...