Adequate cardiac output is necessary in order to supply oxygen and other nutrients to all body tissues. Cardiac output is influenced by stroke volume and heart rate. Factors affecting the stroke volume include PRELOAD, CONTRACTILITY and AFTERLOAD.
In the following conditions, indicate what factor/s influence the cardiac output: PRELOAD, CONTRACTILITY, AFTERLOAD, HEART RATE. Explain why the factor/s affects cardiac output in 1 to 2 sentences.
a. High blood pressure
Any element that boosts heart rate, stroke volume, or both in order to increase cardiac output will raise blood pressure and encourage blood flow. Thus, premised on this scenario, less elastic, narrow arteries will make it more challenging for blood to circulate effectively throughout the body (American Heart Association, 2022).
b. Massive bleeding
Acute blood loss reduces blood volume, which lowers central venous pressure and decreases heart filling. As a result, cardiac output and arterial pressure are decreased (Klabunde, 2021).
c. The drug dopamine
Unlike other inotropic drugs, Dopamine is a direct-acting catecholamine that yields various benefits for treating visceral hypoperfusion conditions including shock and refractory heart failure for the particular reason that it enhances myocardial contractility. Therefore, the inception of such a phenomena would boil down to an increased stroke volume, heart rate, and cardiac output (Reid & Thompson, 1975).
d. Running a sprint
The intersection between the pulmonary ventilation and cellular respiration lies in the cardiovascular system as the heart must pump blood at a sufficient velocity to ensure an adequate and continuous supply of oxygen (Evans, 1985). Owing to this ground, workload will cause a proportional rise in heart rate when running.
e. Hyperthyroidism with increased secretion of thyroid hormones
The most frequent cause of hyperkinetic circulatory illness is hyperthyroidism. Along with its cellular effects, hyperthyroidism also affects the heart's hemodynamics, increasing preload and contractility while lowering systemic vascular resistance raises cardiac output (Osuna et al., 2017).
f. Massive myocardial infarction (cardiac tissue death)
Cardiac function is compromised by the loss of viable myocardium in the above mentioned case. Such incidents can result in decreased cardiac output and, in extreme cases, cardiogenic shock (Mechanic et al., 2022).
g. Hypothermia
A reflex adrenergic vasoconstriction of the skin (noradrenalin) occurs when the core temperature is reduced (hypothermia). As bradycardia increases, cardiac output decreases to below a core temperature of 34 degrees Celsius (Deussen, 2007).
h. Emotional distress
Emotional tension sets off a chain reaction in the body and in the process, stress hormones namely cortisol and adrenaline are released. This triggers the heart to beat more quickly, makes blood arteries constrict, and also accentuates the intensity of blood pressure (Torpy et al., 2007).