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Transcatheter pulmonary valve replacement (TPVR), also known as percutaneous pulmonary valve implantation (PPVI), is the replacement of the pulmonary valve via catheterization through a vein. It is a significantly less invasive procedure in comparison to open heart surgery and is commonly used to treat conditions such as pulmonary atresia .
Vascular resistance is the resistance that must be overcome for blood to flow through the circulatory system.The resistance offered by the systemic circulation is known as the systemic vascular resistance or may sometimes be called by another term total peripheral resistance, while the resistance caused by the pulmonary circulation is known as the pulmonary vascular resistance.
The Windkessel analogy illustrated. Windkessel effect (German: Windkesseleffekt) is a term used in medicine to account for the shape of the arterial blood pressure waveform in terms of the interaction between the stroke volume and the compliance of the aorta and large elastic arteries (Windkessel vessels) and the resistance of the smaller arteries and arterioles.
To reconstruct the right-sided exit, a pulmonary valve from a cadaver (homograft), or a stentless xenograft, is used to replace the removed pulmonary valve. [ 1 ] [ a ] Compared to a mechanical valve replacement , it avoids the requirement for thinning the blood , has favourable blood flow dynamics , allows growth of the valve with growth of ...
In contrast to the Hickman line, the tip of a Groshong line has a three-way valve, which is formed by a slit in the sidewall of the catheter tip. The valve opens outward during infusion, and opens inward during blood aspiration. When not being accessed, the valve remains closed.
If H i is 0.40 one must remove at least 7.5 units of blood during ANH, resulting in an H m of 0.20 to save two units equivalence. Clearly, the greater the H i and the greater the number of units removed during hemodilution, the more effective ANH is for preventing homologous blood transfusion.
The device consisted of an elastic fluid-filled collapsible-tube mounted inside a chamber filled with air. The static pressure inside the chamber was used to control the degree of collapse of the tube, so providing a variable resistor. This resistance was used to simulate TPR, or total peripheral (vascular) resistance.
The classic definition by MP Spencer and AB Denison of compliance is the change in arterial blood volume due to a given change in arterial blood pressure ().They wrote this in the "Handbook of Physiology" in 1963 in work entitled "Pulsatile Flow in the Vascular System".