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TELECONFRENCES
2004
The Changing Left Ventricle

2003
Aortic Valve Disease: New Dimensions in Evaluation and Management

2002
Heart Failure: Echo's Role in and Emerging Health Crisis

2001
Chest Pain in Children & Adults: The Role of Echo

2000
Mitral Regurgitation: New Concept

1998
The Falling Left Ventricle: Diastolic & Systolic Function

1997
Changing the Outcome of Coronary Artery Disease
ECHO GRAND ROUNDS
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Chest Pain in Children and Adults

Mitral Regurgitation: New Concepts

Diastolic and Systolic Function

Changing the Outcome of CAD

BROADCAST SUPPLEMENTS
2000 MV
2001 Chest Pain
2002 Heart Failure


The Doppler Principle and the Study of Cardiac Flows
Blood Flow Patterns
Fig.1.2

Blood flow through the heart and great vessels has certain characteristics that can be measured using Doppler instruments designed for medical use. For the purpose of understanding flow patterns in the heart, it is important to recognize the difference between laminar flow and turbulent (or disturbed) flow. Laminar flow is flow that occurs along smooth parallel lines in a vessel so that all the red cells in an area are moving at approximately the same speed and in the same direction (Fig. 1.2). Due to friction, flow is always slightly slower near the walls of a vessel. With the pulsations of the heart, the red cells generally accelerate and decelerate at approximately the same speed. Flow in most of the cardiovascular system, including the heart and great vessels, is normally laminar and rarely exceeds the maximum velocity of 1.5 m/sec.

In contrast, turbulent or disturbed flow is present when there is some obstruction that results in a disruption of the normal laminar pattern. This causes the orderly movement of red blood cells to become disorganized and produces various whirls and eddies of differing velocities and directions. Obstruction to flow usually also results in some increase in velocity. Thus, turbulent flow is characterized by disordered directions of flow in combination with many different red cell velocities. If the obstruction is significant, some of the red blood cells may be moving at higher velocities than normal and may reach speeds of 7 m/sec. Turbulent flow is usually an abnormal finding and is considered indicative of some underlying cardiovascular pathology.

Fig.1.3

Abnormal flows are therefore generally characterized by turbulence and any increase in velocity. As an example, consider blood flow in the ascending aorta during systole. If the aorta and aortic valve are normal, then this flow is laminar. However, the presence of a valvular stenosis will induce a turbulent flow pattern. Figure 1.3 shows that a narrowed aortic valve orifice interrupts the parallel lines of normal laminar flow and produces turbulent flow. The resulting jet of blood creates a short segment within the proximal aorta with complex flow and velocity characteristics.

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