Cardiac Output & Cardiac Cycle

Front 1

With atrial flutter, atrial fibrillation, or junctional rhythms a portion of left ventricular filling is lost; what percent of left-ventricular end-diastolic volume is normally contri­buted by atrial contraction ("kick" or "prim­ing")?

Back 1

Passive diastolic filling usually accounts for 75% of left-ventricular filling, with atrial contraction causing an additional 25% filling of ventricles. Stoelting states: "During the latter portion of diastole, the atria contract to deliver about 30% of the blood that normally enters the ventricle during each cardiac cycle." [Guyton, TMP. lle. 2006 pp107-108; Stoelting, PPAP. 4e. 2006 pp751]

Front 2

What is the normal range for stroke volume in ml in a 70 kg male? Write the formula for stroke index (SI). What is the normal range for stroke volume index?

Back 2

The normal range for stroke volume is 60-90 ml. Stroke index 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. [Barash, Clinical Anes. 5e. 2006 pp8611

Front 3

Define ejection fraction, and state its normal range.

Back 3

Ejection fraction (EF) is the ratio of stroke volume (end-diastolic volume minus end-systolic volume) to end-diastolic volume. EF = SV/EDV = (EDV-ESV)/EDV. The normal range is O.6-O.8, or 60-80%. [Barash, Clin­ical Anes. 5e. 2006 pp861t]

Front 4

What are the two determinants of cardiac output? If stroke volume is 70 ml and heart rate is 70 beats/min what is the cardiac out­put?

Back 4

Stroke volume and heart rate are the two determinants of cardiac output. 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 70 mi/beat x 70 beats/min = 4,900 ml/min = 4.9 liters/min. [Authors; Barash, Clinical Anes. 5e. 2006 pp861t; Morgan, et al., Gin. Anesth. 4e. 2006 pp42OJ

Front 5

What is cardiac index? What is the normal range for cardiac index?

Back 5

Cardiac index (CI) is cardiac output (C0) divided by body surface area (BSA) in meters squared. CI=CO/BSA. Normal cardiac index ranges from 2.5-4.O 1/min/m2. [Barash, Clinical Anes. 5e. 2006 pp861t; Guyton, TMP. lle. 2006 pp232]

Front 6

Starling's law of the heart relates ventricular filling during diastole to what?

Back 6

Starling's law of the heart relates ventricular filling during diastole to the amount of blood ejected during systole. The greater the ventricular filling during diastole (i.e., the greater the preload), the greater the quantity of blood pumped into the aorta during systole. [Guyton, TMP. l le. 2006 pp112]

Front 7

Describe the process that causes ventricular myocyte relaxation (lusitropy).

Back 7

Ventricular myocyte contraction requires increased intracellular calcium. Thus, for the ventricular myocyte to relax, intracellular calcium must be reduced back to resting levels. Calcium is sequestered in the sarcoplasmic reticulum (SR) through energy-dependent processes. [Guyton and Hall, TMP, 2000, pp98-99; Duke, Secrets, 2000, p194; Authors]-02 [Guyton, TMP. lle. 2006 pp106]

Front 8

Name the organs in the vessel rich group (VRG). What percent of cardiac output goes to each of these organs?

Back 8

The brain, kidney, liver, lungs, heart. digestive tract, and endocrine tis­sues are organs of the vessel rich group (VRG). These are the well- perfused organs. 25% of the cardiac output goes to the liver; 4-5% (225 ml/min) to the heart; 15% to the brain; 20% to the kidneys; and 100% to the lungs. [Guyton, TMP. lle. 2006 pp196t; Stoelting, PPAP. 4e. 2006 pp31; Morgan, et al., Clin. Anesth. 4e. 2006 pp158]

Front 9

What percent of the right heart's cardiac output traverses the pulmonary circulation? Bronchial circulation?

Back 9

0ne-hindered percent (100%) of the blood pumped by the right heart traverses the pulmonary circulation and 0% traverses the bronchial circu­lation. [Guyton, TMP. lle. 2006 pp485; Stoelting, PPAP. 4e. 2006 pp741]

Front 10

What percent of the left heart's output traverses the bronchial circulation? Vessels delivering blood to the bronchial circulation arise from what arteries?

Back 10

1-2% of the left heart's output traverses the bronchial circulation. The bronchial circulation arises from the thoracic aorta and intercostal arteries. [Stoelting, PPAP. 4e. 2006 pp741; Guyton, TMP. lle. 2006 pp483]

Front 11

®In words, describe where isovolumetric relaxation occurs on the left ventricular pressure-volume loop.

Back 11

Isovolumetric relaxation occurs from closure of the aortic valve to opening of the mitral valve on the left ventricular pressure-volume loop. [Nagel­hout & Zaglaniczny, NA. 3e. 2005 pp436]

Front 12

®In words, describe where isovolumetric contraction occurs on the left ventricular pressure-volume loop.

Back 12

Isovolumetric contraction occurs from closure of the mitral valve to open­ing of the aortic valve on the left ventricular pressure-volume loop. [Na­gelhout & Zaglaniczny, NA. 3e. 2005 pp436]