a. High blood pressure
- People with high blood pressure have a higher blood volume. With this, there will be an increase in preload, which would also increase the stroke volume and cardiac output.
b. Massive bleeding
- Massive bleeding, or hemorrhage, stresses the circulatory system and reduces tissue blood flow, cardiac effort, and blood pressure. The heart's reaction to bleeding depends on sympathetic nervous system activation and preload and afterload reduction.
c. The drug dopamine
- Hypotension is treated with dopamine. Excessive doses of this positive inotropic medication increase afterload and exacerbate heart failure because of peripheral vasoconstriction.
d. Running a sprint
- Running demands a left ventricular cardiac output four times greater than normal to oxygenate muscles. Preload and afterload in the left ventricle decrease markedly.
e. Hyperthyroidism with increased secretion of thyroid hormones
- Hyperthyroidism is linked to elevated thyroid hormone levels that have negative effects on the heart. Thyroid hormones promote an increase in heart rate and contractility, which increases the risk of stroke.
f. Massive myocardial infarction (cardiac tissue death)
- The influx of blood from upstream dilates the quickly failing ventricle (myocardial infarction), which subsequently calls upon the preload reserve to restore stroke volume at the cost of an increase in ventricular radius (afterload) and left atrial pressure.
g. Hypothermia
- When one is hypothermic, their heart rate decreases noticeably, and their stroke volume rises noticeably. Preload, afterload, and mean arterial pressure on the stroke volume all rise when the temperature falls.
h. Emotional distress
- Stress increases the heart's output and contractility. Heart rate, contractility, stroke volume, and cardiac output all rise in response to emotional arousal due to increased sympathetic activation and the release of epinephrine and norepinephrine.