Using the Wiggers Diagram below calculate the following A) Heart Rate B) Stroke

Question

Using the Wiggers Diagram below calculate the following

A) Heart Rate

B) Stroke Volume

C) Cardiac Output

D) Mean Arterial Pressure

This diagram tollows left heart and aortic preesures, left ventricular volume, and the ECG through one cardiac cycle. The boxed letters rofer to Concept Checks 28-30. Time (msec) 100 200 500 700 800 ORS complex complax Electro- Dicrotic notch Aorta Preesure (mm Hg) Left venticular proesure Left atrial sounds 135--- Lett volume (mL) 65 Atrial systole Atrial Ventricular diastole Atrial systole Isovolumic Ventricular systcle Early ventricular Late ventricular Atrial systcle

Explanation / Answer

(A) For Heart Rate just select two points on the Left Ventricular Pressure graph on each cycle where time is easy to observe on the x-axis.

First,

t1 = 0 msec for first beginning of Atrial Systole

t2 = 800 msec or 0.8 sec for second beginning of Atrial Systole

Now,

Heart rate = 60/(t2 - t1) = 60/(0.8 - 0) = 75 beats per minute

(B)

Stroke Volume = EDV - ESV

EDV is End Diastolic Volume which the amount of blood in the ventricle right before ventricular systole

ESV is End Systolic Volume which is amount of blood left in theVentricle after Ventricular Systole.

EDV on the graph is point E so EDV = 135 mL

ESV on the graph is point F so ESV = 65 mL

So, Stroke Volume = 135-65 = 70mL

(C) Cardiact Output = Heart Rate * Stroke Volume = 75 * 70 / 1000 = 5.25 L/min or 5250 mL/min

(D)

Mean Arterial Pressure = (2 * Diastolic Pressure + Systolic Pressure ) / 3

Diastolic Pressure = (2 * 60 + 90 ) / 3 = 70 mmHg

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