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A unifying explanation of the aortic pulse waveform in humans

A unifying explanation of the aortic pulse waveform in humans. Dr Justin Davies International Centre for Circulatory Health Imperial College & St Mary’s Hospital. A unifying explanation of the aortic pulse waveform in humans. Dr Justin Davies International Centre for Circulatory Health

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A unifying explanation of the aortic pulse waveform in humans

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  1. A unifying explanation of the aortic pulse waveform in humans Dr Justin Davies International Centre for Circulatory Health Imperial College & St Mary’s Hospital

  2. A unifying explanation of the aortic pulse waveform in humans Dr Justin Davies International Centre for Circulatory Health Imperial College & St Mary’s Hospital No conflicts of interest to declare

  3. What accounts for the change in shape of the pressure wave form? Adolescent Middle-aged Elderly McDonald’s Blood Flow in Arteries, 4th Edition (1998), Arnold.

  4. Morphological features of the arterial pressure wave Inflection point Elastic recoil of the aortic windkessel 2 3 Systolic upstroke 1

  5. Arterial Windkessel Systole

  6. Arterial Windkessel Systole Diastole

  7. Morphological features of the arterial pressure wave Inflection point Elastic recoil of the aortic windkessel 2 3 Systolic upstroke 1

  8. Simple separation of pressure waveform Apparent backward pressure Apparent forward pressure

  9. Simple separation of pressure waveform Apparent backward pressure Apparent forward pressure

  10. Aortic valve closure When the aortic valve is closed…. Where does forward pressure come from in diastole? Apparent backward pressure Apparent forward pressure

  11. Artefacts of simple separation of pressure waveform Apparent backward pressure Total pressure = Forwards originating + Reflected pressure Apparent forward pressure

  12. Study Aims

  13. Study Aims • Use the combined windkessel-separation technique to explain the arterial pressure waveform

  14. Study Aims • Use the combined windkessel-separation technique to explain the arterial pressure waveform • Assess the relative contributions forward and backward pressure and the arterial windkessel make to augmentation pressure

  15. Study Aims • Use the combined windkessel-separation technique to explain the arterial pressure waveform • Assess the relative contributions forward and backward pressure and the arterial windkessel make to augmentation pressure • Assess how the arterial windkessel relates to pulse wave velocity

  16. Study Design

  17. Study Design Subjects undergoing diagnostic coronary angiography

  18. Study Design Subjects undergoing diagnostic coronary angiography Simultaneous haemodynamic measurements were made at aortic root Doppler Flow wire (Flowire, Volcano Therapeutics) Pressure wire (Wavewire, Volcano Therapeutics)

  19. Patient demographics • 19 subjects • 54 ±13 years old • 9 Female • 145/80 mmHg

  20. Pressure separation following windkessel subtraction Simple wave separation Pressure above diastolic (mm Hg) Time (ms)

  21. Pressure separation following windkessel subtraction Simple wave separation Pressure above diastolic (mm Hg) Time (ms)

  22. Effects of windkessel subtraction to pressure separation Pressure above diastolic (mmHg) Time (ms)

  23. Effects of windkessel subtraction to pressure separation Pressure above diastolic (mmHg) Time (ms)

  24. Effects of windkessel subtraction to pressure separation dPwk (t) = dPwk x dVwk(t) = flowin(t) – flowout(t) dt dVwk(t) dt C Pressure above diastolic (mmHg) Time (ms)

  25. Effects of windkessel subtraction to pressure separation dPwk (t) = dPwk x dVwk(t) = flowin(t) – flowout(t) dt dVwk(t) dt C Pressure above diastolic (mmHg) Time (ms)

  26. Effects of windkessel subtraction to pressure separation dPwk (t) = dPwk x dVwk(t) = flowin(t) – flowout(t) dt dVwk(t) dt C Pressure above diastolic (mmHg) Time (ms)

  27. Effects of windkessel subtraction to pressure separation dPwk (t) = dPwk x dVwk(t) = flowin(t) – flowout(t) dt dVwk(t) dt C Pressure above diastolic (mmHg) Time (ms)

  28. Effects of windkessel subtraction to pressure separation Excess Pressure Pressure above diastolic (mmHg) Windkessel Pressure Time (ms)

  29. Pressure separation following windkessel subtraction Simple wave separation Separation after windkessel subtraction Pressure above diastolic (mm Hg) Time (ms)

  30. Pressure separation following windkessel subtraction Simple wave separation Separation after windkessel subtraction Pressure above diastolic (mm Hg) Pressure above diastolic (mm Hg) Time (ms) Time (ms)

  31. Contributors to augmentation pressure

  32. Contributors to augmentation pressure Augmentation pressure

  33. Contributors to augmentation pressure Augmentation pressure Forward pressure wave

  34. Contributors to augmentation pressure Augmentation pressure Reflected pressure wave + Forward pressure wave

  35. Contributors to augmentation pressure Windkessel pressure Augmentation pressure + Reflected pressure wave + Forward pressure wave

  36. Contributors to augmentation pressure reflected pressure 3% forward pressure 15% Augmentation pressure windkessel 82%

  37. Contributors to augmentation pressure reflected pressure 3% forward pressure 15% Augmentation pressure windkessel 82%

  38. Windkessel: a major determinate of the augmentation pressure

  39. Windkessel increases with gold standard of arterial compliance

  40. Windkessel increases with gold standard of arterial compliance r=0.7 p<0.001 Peak windkessel Pressure (mmHg) Wave speed (m/s)

  41. What accounts for the change in shape of the pressure wave form? Adolescent Middle-aged Elderly

  42. What accounts for the change in shape of the pressure wave form? Adolescent Middle-aged Elderly

  43. What accounts for the change in shape of the pressure wave form? Adolescent Middle-aged Elderly • Explains shape of pressure wave

  44. What accounts for the change in shape of the pressure wave form? Adolescent Middle-aged Elderly • Explains shape of pressure wave • Biological plausibility

  45. What accounts for the change in shape of the pressure wave form? Adolescent Middle-aged Elderly r=0.7 p<0.001 Peak windkessel Pressure (mmHg) Close correlation between windkessel and pulse wave velocity Wave speed (m/s)

  46. What accounts for the change in shape of the pressure wave form? Adolescent Middle-aged Elderly

  47. Key Findings • Waves and windkessel make up pressure waveform • Windkessel greatest contributor to augmentation pressure • Windkessel highly correlated with PWV Dr Jamil Mayet Prof Alun Hughes Dr Darrel Francis Prof Kim Parker Coronary Flow Trust

  48. Can the result of the Café study be explained by the arterial windkessel?

  49. Can the result of the Café study be explained by the arterial windkessel?

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