1. 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
High blood pressure or most referred as hypertension is the elevation of mean blood pressure and can lead to an increase in cardiac output.
b. Massive bleeding
Hemorrhagic shock is clinical syndrome resulting from decreased blood volume (hypovolemia) caused by blood loss, which leads to reduced cardiac output and organ perfusion.
c. the drug dopamine
Dopamine is a medication used for low blood pressure, it is used in clinical settings to support cardiac output and blood pressure and improve diuresis. Experimental studies suggest that dopamine may reduce splanchnic perfusion and redistribute blood flow locally.
d. Running a sprint
With activities such as running, your body may need three or four times your normal cardiac output, making it increase, because your muscles need more oxygen when you exert yourself. During exercise, your heart typically beats faster so that more blood gets out.
e. Hyperthyroidism with increased secretion of thyroid hormones
Hyperthyroidism causes high cardiac output and left ventricular hypertrophy in the early stage and biventricular dilation and congestive heart failure in the late stage.
f. Massive myocardial infarction (cardiac tissue death)
Subsequent reduced blood flow may result in damage to the heart muscle, or referred to as myocardium, commonly referred to as a “heart attack”. This damage is usually irreversible and can affect the normal pumping capacity of the heart, resulting in decreased cardiac output.
g. Hypothermia
In severe hypothermia resistance in the coronary vascular bed is reduced and flow continues despite very low aortic pressure. Moderate artificial acceleration of the hypothermic heart at constant coronary perfusion produces a decrease in the coronary blood flow.
h. Emotional distress
When experiencing stress or emotional stress, it causes your heart to beat more rapidly and your blood vessels to narrow to help push blood to the center of the body. With increased heart rate and blood sugar levels, cardiac output is increased.
References:
Mayet, J., & Hughes, A. (n.d.). Cardiac and vascular pathophysiology in hypertension. National Library of Medicine. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1767863
Klabunde, R., E. (n.d.). Cardiovascular physiology concepts (3rd ed.). Wolters Kluwer (2021). https://www.cvphysiology.com/Blood%20Pressure/BP031#:~:text=Hemorrhagic%20shock%20is%20a%20clinical,caused%20by%20ruptured%20aortic%20aneurism
Jakob, S., M., Ruokonen, E., & Takala, J. (n.d.). Effects of dopamine on systemic and regional blood flow and metabolism in septic and cardiac surgery patients. National Library of Medicine. https://pubmed.ncbi.nlm.nih.gov/12095139/#:~:text=Dopamine%20is%20used%20in%20the,and%20redistribute%20blood%20flow%20locally
Healthwise staff. (n.d.-b). Cardiac output. Alberta. https://myhealth.alberta.ca/Health/Pages/conditions.aspx?hwid=tx4080abc#:~:text=During%20exercise%2C%20your%20body%20may,gets%20out%20to%20your%20body
Hyperthyroidism with increased secretion of thyroid hormones cardaic output - Google Zoeken. (n.d.). https://www.google.com/search?q=Hyperthyroidism+with+increased+secretion+of+thyroid+hormones+cardaic+output
Coronary Artery Disease. (2020, September 22). Hope for Hearts. https://hopeforhearts.com.au/cardiovascular-disease/coronary-artery-disease/
Berne, R. (n.d.). The Effect of Immersion Hypothermia on Coronary Blood Flow. Ahajournals. https://www.ahajournals.org/doi/pdf/10.1161/01.RES.2.3.236
Content - Health Encyclopedia - University of Rochester Medical Center. (n.d.). https://www.urmc.rochester.edu/encyclopedia/content.aspx?ContentTypeID=134