Читать книгу Manual of Equine Anesthesia and Analgesia - Группа авторов - Страница 93

 Is the force acting to stretch the ventricular fibers at the end of diastole.

 It may be described as either end‐systolic volume or end‐systolic pressure.

 The volume or pressure in the left ventricle is generally used to determine preload.

 It is dictated in large part by venous return.The venules serve as capacitance vessels or reservoirs, storing the majority of the circulating blood volume. They constrict during times of increased demand, thereby increasing venous return and preload. The great veins and the spleen also act as reservoirs for blood.Anesthetic drugs that can change venous return include acepromazine (via vasodilation) and alpha2 agonists (via vasoconstriction).Venous return is affected by a number of factors including circulating blood volume, body position, phase of respiration and respiratory disease (due to changes in intrathoracic pressure) and valvular regurgitation.

 Ideally, an appropriate preload will cause stretch of the myocardium, which will improve contractility and increase SV due to Frank‐Starling's Law of the heart (see Table 3.1).