Cardiac Output and Cardiac Cycle Flashcards
What percent of left-ventricular end-diastolic volume is normally contributed by atrial contraction?
Atrial contraction contributes an additional 25% of left-ventricular filling.
Passive diastolic filling usually accounts for 75% of left-ventricular filling. [Guyton, TMP, 14e. p119]
What is the normal range for stroke volume in ml in a 70 kg male?
The normal range for stroke volume is 70–90 ml.
Stroke index (SI) is stroke volume (SV) divided by body surface area (BSA) in meters squared: SI = (SV)/(BSA). The normal range for stroke volume index is 40–60 ml/beat/m2. [Stoelting, PPAP, 6e. p400]
Define ejection fraction and state its normal range.
Ejection fraction (EF) is the ratio of stroke volume to end-diastolic volume. The normal range is 0.67–0.8, or 67–80%.
EF = SV/EDV = (EDV–ESV)/EDV. [Morgan, et al., Clin. Anes., 6e. p420]
What are the two determinants of cardiac output?
The two determinants of cardiac output are stroke volume and heart rate.
Cardiac output = stroke volume x heart rate. With a stroke volume of 70 ml and a heart rate of 70 beats/min, cardiac output is 4,900 ml/min or 4.9 liters/min. [Authors; Morgan, et al., Clin. Anes., 6e. p353]
What is cardiac index?
Cardiac index (CI) is cardiac output divided by body surface area (BSA) in meters squared.
Normal cardiac index ranges from 2.5–4.0 L/min/m2. [Morgan, et al., Clin. Anes., 6e. p353]
Whose law relates ventricular filling during diastole to the amount of blood ejected during systole?
Starling’s (or Frank-Starling’s) law of the heart.
The greater the ventricular filling during diastole, the greater the quantity of blood pumped into the aorta during systole. [Hall, Guyton and Hall’s TMP, 14e. p245]
What does Starling’s law of the heart relate to?
Starling’s law of the heart relates ventricular filling during diastole to the amount of blood ejected during systole.
The greater the preload, the greater the quantity of blood pumped into the aorta during systole. [Guyton, TMP, 14e. p.245]
Describe the process that causes ventricular myocyte relaxation.
Ventricular myocyte relaxation requires a reduction of intracellular calcium back to resting levels.
Calcium is sequestered in the sarcoplasmic reticulum (SR) through energy-dependent processes. [Guyton, TMP, 14e. p123]
Name the organs in the vessel rich group (VRG).
The organs in the vessel rich group (VRG) include the brain, kidney, liver, lungs, heart, digestive tract, and endocrine tissues.
24% of cardiac output goes to the liver; 4–5% (225 ml/min) to the heart; 14% to the brain; 22% to the kidneys; and 100% to the lungs. [Guyton, TMP, 14e. p206]
What percent of the right heart’s cardiac output traverses the pulmonary circulation?
One-hundred percent (100%) of the blood pumped by the right heart traverses the pulmonary circulation.
0% traverses the bronchial circulation. [Stoelting, PPAP, 6e. p380]
What percent of the left heart’s output traverses the bronchial circulation?
1–2% of the left heart’s output traverses the bronchial circulation.
The bronchial circulation arises from the thoracic aorta and intercostal arteries.
Where does isovolumetric relaxation occur on the left ventricular pressure-volume loop?
Isovolumetric relaxation occurs from closure of the aortic valve to opening of the mitral valve on the left ventricular pressure-volume loop.
[Guyton, TMP, 14e. p122]
Where does isovolumetric contraction occur on the left ventricular pressure-volume loop?
Isovolumetric contraction occurs from closure of the mitral valve to opening of the aortic valve on the left ventricular pressure-volume loop.
[Guyton, TMP, 14e. p122]
