Page 45 - Libro 2

2 — Arterial Physiology
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SUMMARY
The hemodynamics of the arterial system includes unique relationships between pressure, resistance, and flow. Blood flow follows the same rules that govern the movement of other fluids. Understanding the factors that influence the movement of blood flow in the arterial system will make it easier to understand the velocities and waveforms encountered during ultrasound examinations.
Critical Thinking Questions
1. You are examining a patient with a lower extremity bypass graft from the common femoral artery to the popliteal artery. The flow is constant through- out the graft but, at one point, you detect a velocity increase on spectral analysis. What must be happening in this area?
2. Would increasing the viscosity of blood or increasing length of a conduit have a greater effect on decreasing blood flow?
3. You examine a popliteal artery that displays continuous forward (antegrade) flow throughout the entire cardiac cycle. In the absence of any disease or pathology, what is the most likely explanation of these findings?
SUGGESTED READINGS
1. Carter SA. Hemodynamic considerations in peripheral vascular and cerebrovascular disease. In: Zwiebel WJ, Pellerito JS, eds. Introduction to Vascular Ultrasonography. 5th ed. Philadel- phia, PA: Elsevier Saunders; 2005:3–17.
2. Guyton AC, Hall JE. Textbook of Medical Physiology. 11th ed. Philadelphia, PA: Saunders; 2005.
3. Koeppen BM, Stanton BA. Berne & Levy Physiology. 6th ed. Philadelphia, PA: Mosby; 2009.
4. Mohrman DE, Heller LJ. Cardiovascular Physiology. New York, NY: McGraw-Hill; 1997.
5. Oates C, ed. Cardiovascular Haemodynamics and Doppler Waveforms Explained. Cam-
bridge, MA: Cambridge University Press; 2001.
6. Zierler RE. Hemodynamics of normal and abnormal arteries. In: Zierler RE, ed. Strandness’s
Duplex Scanning in Vascular Disorders. 4th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2010:47–55.