Lecture on Hemodynamics

Introduction

• Heart Efficiency: The heart is an efficient, never-stopping pump from utero until death.
• Functionality: Capable of working continuously, beating 70 times per minute.

Heart Anatomy and Function

• Watering Can Analogy: Heart compared to a watering can:
  • Mitral Valve: Entry point of blood.
  • LVOT: Left Ventricular Outflow Tract, represented by the spout.
  • Myocardial Fibers: Twisting motion facilitates heart contraction (clockwise at base, counter-clockwise at apex).

Mitral Valve and Annulus

• Dynamic Structure: The mitral valve and annulus move to accommodate blood flow.
• Annulus Movement: Expands when mitral valve opens, contracts during ventricle contraction.

Blood Flow Patterns

• Flow Imaging: CMR imaging shows blood path through the heart.
• Vortex Patterns: Blood flow creates vortices to minimize contact with chamber walls.

Left Atrium and Ventricle Interaction

• Blood Flow: Blood goes to LV apex, forming small and large vortices.
• Valve Dynamics: Mitral valve acts like a keystone in a Roman arch; opens and closes by blood force.

Vector Flow Mapping

• Color Doppler Imaging: Shows blood flow direction and velocity.
• Mitral and Aortic Valve Dynamics: Blood flow observed before and after valve actions.

EKG and Hemodynamics

• R Wave: Signals start of isovolemic contraction.
• Cardiac Cycles: Involves atrial and ventricular actions, valve states.

Pressure and Doppler Measurements

• Pressure Reflections: Pulmonary artery occlusion and central venous pressures reflect atrial activity.
• Tissue Doppler: Measures annular movement and cardiac events timing.

Blood Flow Dynamics

• Pulmonary Venous Flow: Continuous except during atrial contraction.
• Mitral and Aortic Inflow Patterns: Fast rush of blood compared to steady atrial flow.

Simplified Bernoulli Equation

• Velocity Calculations: Estimation of pressure gradients in heart via Doppler shift.
• Flow Velocity: Standard is 1 meter per second; abnormalities indicate issues like aortic stenosis.

Importance of Vortices

• Efficiency: Vortices are crucial for heart efficiency and forward stroke volume.
• Factors Affecting Efficiency: Timing, diastolic formation, and contraction quality.

Conclusion

• Heart's Role: Optimal function relies on timing, formation, and contraction.
• Abnormalities: Such as arrhythmia or mitral stenosis affect efficiency.
• Adaptation: Body maintains homeostasis but reacts to sudden changes like arrhythmia quickly.

Segue

• Transition to Dr. Jamie Ramsey's presentation on cardiopulmonary bypass physiology.