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Venous blood can once more enter the chest and the heart; cardiac output increases. Return of cardiac output Blood return to the heart is enhanced by the effect of the entry of blood that has been dammed back, causing a rapid increase in cardiac output (24 seconds on). The stroke volume usually rises above normal before returning to a normal level.
Hemodynamically, venous return (VR) to the heart from the venous vascular beds is determined by a pressure gradient (venous pressure - right atrial pressure) and venous resistance (RV). Therefore, increases in venous pressure or decreases in right atrial pressure or venous resistance will lead to an increase in venous return, except when ...
This is because inspiration decreases intra-thoracic pressure relative to atmospheric pressure, which increases blood flow (systemic venous return) to the right atrium of the heart by reducing pressure on the veins, particularly the venae cavae. However, the decrease in intra-thoracic pressure and stretching of the lungs during inhalation also ...
Situational syncope is often triggered by urination, swallowing, or coughing. [2] Carotid sinus syncope is due to pressure on the carotid sinus in the neck. [2] The underlying mechanism involves the nervous system slowing the heart rate and dilating blood vessels, resulting in low blood pressure and thus not enough blood flow to the brain. [2]
The horizontal axis of Guyton diagram represents right atrial pressure or central venous pressure, and the vertical axis represents cardiac output or venous return. The red curve sloping upward to the right is the cardiac output curve, and the blue curve sloping downward to the right is the venous return curve. A steady state is formed at the ...
Superior vena cava syndrome (SVCS), is a group of symptoms caused by obstruction of the superior vena cava ("SVC"), a short, wide vessel carrying circulating blood into the heart. The majority of cases are caused by malignant tumors within the mediastinum , most commonly lung cancer and non-Hodgkin's lymphoma , directly compressing or invading ...
Total anomalous pulmonary venous connection, also known as total anomalous pulmonary venous return, is a rare cyanotic congenital heart defect in which the pulmonary veins drain into the right side of the heart instead of the left, as is usually seen. This can happen within the heart (intracardiac) where it drains into the coronary sinus or ...
The Bainbridge reflex is most strong when heart rate is low; when heart rate is already high, additional venous return to the right atrium (i.e. additional increases in blood volume) will indirectly cause relatively greater stimulation of arterial baroreceptors which will reduce the heart rate.