-What is the typical cardiac axis deviation (in degrees and direction) for a nor
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Question
-What is the typical cardiac axis deviation (in degrees and direction) for a normal healthy heart? What does this mean anatomically and/or physiologically?
-What are the Korotkoff sounds? How does the demonstration of blood flow match up with Korotkoff sounds. (i.e what descriptions of fluid flow match up with these sounds?) How do the Korotkoff sounds match up with determination of systolic and diastolic blood pressure?
-How is mean arterial blood pressure determined? Why is it not just the average between the systolic and diastolic blood pressures?
Explanation / Answer
1.Mean cardiac axis (QRS vector) in normal conditions is about +59°.
it varies between -30°- 110°.
Mean direction of flow of electrical potential at one instance is known as instaneous mean vector.
Degree and directions:
lead I: right to left in horizontal plane. O°
lead II: above downward slightly towards left. 60°
lead III : above downwards, slightly towards right. 120°
aVR: towards upper heart and slightly towards right.210°
aVF: above downward .90°
aVL: from below toward upper heart slightly towards left. -30°- 330°
cardiac vector or axos is the direction at which electrical potential generated in heart travels at an instant.
3. Mean arterial blood pressure = Diastolic pressure +1/3rd of pulse pressure. [ systolic pressure- diastolic pressure]
its just not average because diastolic period of cardiac cycle is longer (0.53s) than the systolic period (0.27s)
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