Preload vs. Afterload Heart Nursing Quiz (RegisteredNurseRN)

Which statement below best describes the term cardiac preload? A. The pressure the ventricles stretch at the end of systole. B. The amount the ventricles stretch at the end of diastole. C. The pressure the ventricles must work against to pump blood out of the heart. D. The strength of the myocardial cells to shorten with each beat.

The answer is B. Cardiac preload is the amount the ventricles stretch at the end of diastole (the filling or relaxation phase of the heart).

Stroke volume plays an important part in cardiac output. Select all the factors below that influence stroke volume: A. Heart rate B. Preload C. Contractility D. Afterload E. Blood pressure

The answers are B, C, and D. Preload, afterload, and contractility all have a role with influencing stroke volume.

A patient with hypovolemic shock is given IV fluids. IV fluids will help _________ cardiac output by: A. decrease; decreasing preload B. increase, increasing preload C. increase, decreasing afterload D. decrease, increasing contractility

The answer is B. IV fluids will increase venous return to the heart. This will increase the amount of fluid that will fill the ventricles at the end of diastole...hence increasing preload and increasing cardiac output.

A patient has a blood pressure of 220/140. The physician prescribes a vasodilator. This medication will? A. Decrease the patient's blood pressure and increase cardiac afterload B. Decrease the patient's blood pressure and decrease cardiac afterload C. Decrease the patient's blood pressure and increase cardiac preload D. Increase the patient's blood pressure but decrease cardiac output.

The answer is B. The patient has a high systemic vascular resistance...as evidence by the patient's blood blood....there is vasoconstriction and this is resulting in the high blood pressure. Therefore, right now, the cardiac afterload is high because the ventricle must overcome this high pressure in order to pump blood out of the heart. If a vasodilator is given, it will decrease the blood pressure (hence the systemic vascular resistance) and this will decrease the cardiac afterload. The amount of the pressure the ventricle must pump against will decrease (cardiac afterload decrease) because the blood pressure will go down (hence the systemic vascular resistance).

___________ is the amount of blood pumped by the left ventricle with each beat. A. Cardiac output B. Preload C. Afterload D. Stroke volume

The answer is D. Stroke volume is the amount of blood pumped by the left ventricle with each beat.

Select the statement below that best describes cardiac afterload: A. It's the volume amount that fills the ventricles at the end of diastole. B. It's the volume the ventricles must work against to pump blood out of the body. C. It's the amount of blood the left ventricle pumps per beat. D. It's the pressure the ventricles must work against to open the semilunar valves so blood can be pumped out of the heart.

The answer is D. Cardiac afterload is the pressure the ventricles must work against to pump blood out of the heart by opening up through the semilunar valves. So, it's the pressure the ventricles must overcome to open the semilunar valves to push blood out of the heart.

True or False: Pulmonary and systemic vascular resistance both play a role with influencing cardiac afterload.

The answer is True. If pulmonary vascular resistance or systemic vascular resistance is high, it will create an increased cardiac afterload. If pulmonary vascular resistance or systemic vascular resistance is low, it will create a decreased cardiac afterload.

What two factors are used to calculate cardiac output? Select all that apply: A. Heart rate B. Blood pressure C. Stroke volume D. Mean arterial pressure

The answers are A and C. Cardiac output is calculated by taking the heart rate and multiplying it by stroke volume. CO = HR x SV

What conditions below can result in an increased cardiac afterload? Select all that apply: A. Vasoconstriction B. Aortic stenosis C. Vasodilation D. Dehydration E. Pulmonary Hypertension

The answers are A, B, and E. Vasoconstriction increases systemic vascular resistance which will increase cardiac afterload. It will increase the pressure the ventricle must pump against to open the semilunar valves to get blood out of the heart. Aortic stenosis creates an outflow of blood obstruction for the ventricle (specifically the left ventricle) and this will increase the pressure the ventricle must pump against to get blood out through the aortic valve. Pulmonary hypertension increases pulmonary vascular resistance which will increase the pressure the right ventricle must overcome to open the pulmonic valve to get blood out of the heart....all of this increase cardiac afterload.

Which treatments below would decrease cardiac preload? Select all that apply: A. IV fluid bolus B. Norepinephrine C. Nitroglycerin D. Furosemide

The answers are C and D. Nitroglycerin is a vasodilator that will dilate vessels, which will decrease venous return to the heart and this will decrease preload. Furosemide is a diuretic which will remove extra fluid from the body via the kidneys. This will decrease venous return to the heart and decrease preload. An IV fluid bolus and Norepinephrine (a vasoconstrictor) will increase venous return to the heart and increase preload.