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A method for detecting chaos in canine myocardial microcirculatory red cell flux
K D Barclay1, G A Klassen, C Young
1School of Health and Human Performance, Dalhousie University, Halifax, Nova Scotia, Canada.
Insights
Red blood cell movement in heart capillaries is chaotic, indicating complex control of oxygen delivery within the microcirculation. This nonlinear dynamics suggests a primary role for the microcirculation in regulating cardiac oxygen supply.
Area of Science:
- Cardiovascular Physiology
- Nonlinear Dynamics
- Microcirculation Research
Background:
- Understanding blood flow dynamics is crucial for cardiac health.
- The microcirculation's role in oxygen delivery is complex and not fully understood.
Purpose of the Study:
- To investigate the chaotic nature of red blood cell movement in the heart's capillary network.
- To analyze the complexity of red blood cell flux using nonlinear methods.
Main Methods:
- Laser Doppler velocimetry was used to measure in situ red blood cell flux in canine hearts.
- Lyapunov exponents and correlation dimension were employed to assess for chaos.
- Simultaneous measurements of epicardial arterial flow and left ventricular pressure were recorded.
Main Results:
- Capillary red blood cell flux exhibited strongly positive Lyapunov exponents, indicating chaotic behavior at most sites.
- Coronary arterial flow and left ventricular pressure showed less evidence of chaos compared to capillary flux.
- Correlation dimension was less effective in distinguishing chaos in capillary flux and arterial flow.
Conclusions:
- Capillary red blood cell flux is nonlinear and chaotic, highlighting the complexity of the microcirculation.
- The primary control for oxygen delivery to cardiac myocytes by red blood cells appears to be within the microcirculation.
- The bifractal nature of capillary red blood cell flux suggests an underlying order in its control mechanisms.
Objective:
To determine whether red cell movement, as measured by laser Doppler velocimetry, in the capillary net of the beating heart is chaotic.
Methods:
Using two dog hearts, in situ red blood cell flux was measured at many sites. Simultaneously, epicardial arterial flow and left ventricular pressure were recorded via transit-time flowmeter and catheter manometer, respectively. The presence or absence of chaos was tested by two methods: Lyapunov exponents and correlation dimension.
Results:
For capillary red cell flux, the Lyapunov was strongly positive at most sites. It was less so for coronary arterial flow and least for left ventricular pressure. Correlation dimension calculation was less able to distinguish the presence or absence of chaos in capillary red cell tissue flux, coronary arterial flow, and left ventricular pressure.
Conclusions:
Capillary red cell flux (movement of red cells in capillaries) is nonlinear, (i.e., chaotic). This complexity suggests that the primary control for oxygen delivery to cardiac myocytes by red blood cells resides in the microcirculation. Also, capillary red cell flux is bifractal, suggesting an ordering of control.