Basic hemodynamic principles viewed through pressure volume relations

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The goal of this webinar is to provide an overview of the fundamental principles of preload, afterload, contractility and lusitropy (diastolic properties), how these are quantified on the pressure-volume diagram, and how they are affected in heart failure. Links are made to underlying properties of cardiac muscle and ventricular structure. After establishing basic concepts, it will be demonstrated how pressure-volume analysis can lead to a quantitative understanding of how heart and vasculature interact to determine stroke volume, cardiac output and blood pressure. The implications for understanding therapeutic effects will also be discussed.

Key Topics:

- Preload, Afterload, Contractility and Lusitropy

- Cardiac Muscle and Ventricular Structure

- Understanding Heart-Vasculature Interactions

- PV Loops in Heart Failure

- Understanding Therapies and Their Effects on Cardiac Pump Performance

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Basic hemodynamic principles viewed through pressure volume relations

  1. 1. InsideScientific is an online educational environment designed for life science researchers. Our goal is to aid in the sharing and distribution of scientific information regarding innovative technologies, protocols, research tools and laboratory services.
  2. 2. Cardiovascular Physiology and Hemodynamics Daniel Burkhoff MD PhD Adjunct Associate Professor Columbia University
  3. 3. 4 If your research involves studying the effects of altered genes, cells, extracellular matrix, drugs, etc, on cardiovascular properties, there are several key concepts, indexes and measurement techniques you should be aware of: PRELOAD AFTERLOAD CONTRACTILITY LUSITROPY
  4. 4. 5 Resources Harvi Interactive, simulation-based textbook for the iPad iPad 2, 3 and mini (iOS 7)
  5. 5. 6 Foundations in Cellular Physiology
  6. 6. 7 The Sarcomere
  7. 7. 8 Sarcomere F-L Relation
  8. 8. 9 Muscle Heart Force - Length Pressure - Volume
  9. 9. 10 Integrated Cardiovascular Physiology Ventricular-Vascular Interactions Cardiac Output Arterial Blood Pressures Venous Blood Pressures
  10. 10. 11 Physiology of the Intact Heart
  11. 11. The Cardiac Cycle: The Classic “Wiggers” Diagram 12
  12. 12. 0 25 50 75 100 125 150 0 25 50 75 100 125 150 LV Volume (ml) LVPressure(mmHg) MV Closes AoV Opens AoV Closes MV Opens Isovolumic Contraction Isovolumic Relaxation Filling Ejection The Cardiac Cycle Pressures-Volumes Loop 13
  13. 13. LV Volume (ml) LVPressure(mmHg) SV Stroke Volume End Diastolic Volume End Systolic Volume SV = ESV-EDV EF = SV/EDV CO=SV.HR Volumes Retrievable from the PV Loop ESV EDV 14
  14. 14. 0 75 150 0 75 150 LV Volume (ml) LVPressure(mmHg) DBP SBP Pes EDP LAP Systolic Blood Pressure End Systolic Pressure Diastolic Blood Pressure End Diastolic Pressure Left Atrial Pressure 15 Pressures Retrievable from the PV Loop
  15. 15. 16 Pressure-Volume Relations The Basics
  16. 16. 0 25 50 75 100 125 150 0 25 50 75 100 125 150 LV Volume (ml) LVPressure(mmHg) 17 Pressure-Volume Loops and Relationships
  17. 17. 0 75 150 0 LV Volume (ml) LVPressure (mmHg) 10 20 30 End-Diastolic Pressure-Volume Relationship 18 Vo P = β(eα(V-Vo)-1)
  18. 18. 0 25 50 75 100 125 150 0 25 50 75 100 125 150 LV Volume (ml) LVPressure(mmHg) Vo Ees End-Systolic Pressure-Volume Relationship (ESPVR) Pes = Ees(Ves-Vo) 19 End-Systolic Pressure-Volume Relationship
  19. 19. 20 EDPVR and ESPVR define the boundaries within which the PV Loop sits, independent of “preload” and “afterload”
  20. 20. 21 Preload
  21. 21. 22 Sarcomere Isometric F-L Relation
  22. 22. 0 50 100 150 0 50 100 150 LV Volume (ml) LVPressure(mmHg) Preload: The load imposed on the ventricle at the end of diastole. The most common measures of preload include end-diastolic volume (EDV) and end-diastolic pressure (EDP). 23 Preload: Ventricular Level EDV, EDP
  23. 23. 0 50 100 150 0 50 100 150 LVPressure(mmHg) Increased Preload Preload: The load imposed on the ventricle at the end of diastole. The most common measures of preload include end-diastolic volume (EDV) and end-diastolic pressure (EDP). 24 Preload: Ventricular Level LV Volume (ml)
  24. 24. 0 50 100 150 0 50 100 150 LVPressure(mmHg) Decreased Preload Preload: The load imposed on the ventricle at the end of diastole. The most common measures of preload include end-diastolic volume (EDV) and end-diastolic pressure (EDP). 25 Preload: Ventricular Level LV Volume (ml)
  25. 25. 0 50 100 150 0 50 100 150 LVPressure(mmHg) Decreased Preload Increased Preload The different loops are obtained with different preloads, but constant contractility and afterload. 26 Preload: Ventricular Level LV Volume (ml)
  26. 26. 27 Afterload
  27. 27. 28 Afterload: Intact Ventricle • There are several different indexes of ventricular afterload, each with its own merits and drawbacks: • Myocardial wall stress • Arterial Pressure • Arterial Resistance • Arterial Impedance
  28. 28. 29 Afterload: Total Peripheral Resistance • Conceptually, for the intact LV, a measure of afterload should provide a quantitative index that uniquely characterizes the arterial system independent of preload and contractility • Such an index can be derived from the relationship between pressure and flow through the system • One index, total peripheral resistance (TPR), is based on Ohms law and is simply the ratio between mean pressure across the system and mean flow: TPR = (MAP-CVP)/CO MAP CVP Flow
  29. 29. 0 50 100 150 0 50 100 150 LV Volume (ml) LVPressure(mmHg) Afterload: The mechanical load on the ventricle during ejection. Under normal physiological conditions, this is determined by the arterial system. The most common index of afterload is total peripheral resis-tance (TPR): TPR = (MAP-CVP)/CO 30 Afterload: Impact on LV Performance
  30. 30. 0 50 100 150 0 50 100 150 LV Volume (ml) LVPressure(mmHg) Increased TPR 31 Afterload: Impact on LV Performance Despite constant preload and contractility: Increased TPR • Increased pressure • Decreased SV
  31. 31. 0 50 100 150 0 50 100 150 LV Volume (ml) LVPressure(mmHg) Decreased TPR 32 Afterload: Impact on LV Performance Despite constant preload and contractility: Increased TPR • Increased pressure • Decreased SV Decreased TPR • Decreased SV • Increased pressure
  32. 32. 0 50 100 150 0 50 100 150 LV Volume (ml) LVPressure(mmHg) Decreased TPR Increased TPR 33 Afterload: Impact on LV Performance Despite constant preload and contractility: The pressure-volume loop falls within the boundaries established by the ESPVR and EDPVR
  33. 33. 34 Contractility
  34. 34. 35 Contractility: The concept applied to Isolated Muscle
  35. 35. 36 Contractility: The concept applied to the Left Ventricle
  36. 36. 0 50 100 150 0 25 50 75 100 125 150 LV Volume (ml) LVPressure(mmHg) Ees Ees 37 Contractility
  37. 37. 38 Lusitropy Diastole
  38. 38. The EDPVR is nonlinear and defines the boundary for the position of the end-diastolic pressure-volume point of the PV loop: Ped= β(eα(Ved-Vo)-1) 39 Lusitropy: Passive Diastolic Properties
  39. 39. 40 Lusitropy: Passive Diastolic Properties
  40. 40. 41 Lusitropy: Passive Diastolic Properties
  41. 41. 42 Lusitropy: Passive Diastolic Properties The EDPVR shifts leftward: • Hypertrophic cardiomyopathies • Infiltrative diseases (amyloid, sarcoid) • Restrictive cardiomyopathy
  42. 42. 43 Lusitropy: The Rate of Relaxation The decay of pressure during the isovolumic relaxation phase of diastole follows a roughly exponential time course. P = e-t/τ Active relaxation can therefore be characterized by τ, the time constant of relaxation. Isovolumic Relaxation LVP
  43. 43. 44 Lusitropy: The Rate of Relaxation Isovolumic Relaxation τLVP The decay of pressure during the isovolumic relaxation phase of diastole follows a roughly exponential time course. P = e-t/τ Active relaxation can therefore be characterized by τ, the time constant of relaxation.
  44. 44. 45 τ is influenced by: • Contractile element isoforms • Heart Rate • τ decreases significantly as heart rate increases • Energy Supply • τ increases significantly during myocardial ischemia • β Stimulation • τ decreases significantly with β-adrenergic stimulation or any drugs that increase ATP Lusitropy: The Rate of Relaxation
  45. 45. 46 Lusitropy • Passive diastolic properties: the extent of relaxation • Characterized by the EDPVR • Compliance • Stiffness • Capacitance • Active relaxation: the rate of relaxation • Indexed by τ • Impact on cardiac performance highly dependent on heart rate • Concept of “incomplete relaxation”
  46. 46. 47 Cardiac Performance cardiac output, blood pressure, etc Determined by the interaction between the heart and vascular systems
  47. 47. 48 SUMMARY PRELOAD AFTERLOAD CONTRACTILITY LUSITROPY
  48. 48. 49 Harvi Interactive, simulation-based textbook for the iPad iPad 2, 3 and mini (iOS 7)
  49. 49. Thank you for taking part in this event.We encourage all attendees to register at www.insidescientific.com for notifications about future webinars. Hemodynamic Assessment Series– Part 1: PV Loop Case Study by Transonic Improve PV Loop Results by Heating & Monitoring During Surgery by Indus Instruments Understanding the Translational Value of PV Loops from Mouse to Man by Millar COMING SOON…

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