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diastolic dysfunction

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diastolic dysfunction

  1. 1. Diastolic function of the heart, Phases, Enddiastolic volume & pressure, Factors affecting
  2. 2. Diastole • time period during which the myocardium loses its ability to generate force and shorten and returns to an unstressed length and force • Begins with the closure of aortic/pulmonic valves • 2/3rd of cardiac cycle • Total duration : 0.53 sec at HR of 72/min • Active & passive components
  3. 3. Active Relaxation • occurs in a series of energy- consuming steps • Release of calcium from troponin C, • detachment of the actin-myosin cross-bridge, • phosphorylation of phospholamban, • Sarcoplasmic reticulum calcium ATPase–induced calcium sequestration into the sarcoplasmic reticulum, • sodium/calcium exchanger– induced extrusion of calcium from the cytoplasm, • extension of the sarcomere to its rest length P m t m . c s ( p b e S r u s g a r a e f t
  4. 4. Phases of diastole • Protodiastole • Isovolumic relaxation • Rapid filling • Diastasis • Atrial kick
  5. 5. • The isovolumic relaxation phase is energy dependent • does not contribute to ventricular filling • Auxotonic relaxation phases (phases 2 through 4), ventricular filling occurs against pressure gradient (passive) • Encompasses a period during which the myocardium is unable to generate force and filling of the ventricular chambers takes place
  6. 6. Protodiastole – Once the ventricular muscle is fully contracted, the already falling ventricular pressures drop more rapidly – 0.04sec – ends when the momentum of the ejected blood is overcome and the aortic and pulmonary valves close
  7. 7. Isovolumic relaxation – from closure of the aortic valve to opening of the mitral valve – 0.03-0.06sec – Energy dependent – Left ventricular volume constant (no filling) – left ventricular pressure decreases
  8. 8. Rapid filling stage – Starts with opening of mitral valve – transmitral pressure gradient drives LV filling – 70-80% of filling – Early filling correlates with the E-wave of transmitral flow doppler
  9. 9. Diastasis – period of low flow in mid-diastole – Lt.Atrial Pressure=Lt.Ventricular Pressure – Little oR NO flow <5% – correlates with the interval between E- and the A-wave of the transmitral Doppler signal
  10. 10. Atrial kick – Atrial contraction leads to late rapid filling – Contributes 15-25% of LVEDV – correlates with the A-wave of the mitral inflow signal – Becomes important in AF, high ventricular rate, stiff ventricle
  11. 11. Diastolic time
  12. 12. Factors affecting diastolic function • passive chamber stiffness (remodelling) • elastic recoil of the ventricle • the diastolic interaction between the two ventricular chambers • systolic volume load • atrial properties (rhythm,contractn) • Drugs (catecholamines)
  13. 13. Effects of beta stimulation • Increases both ionotropy and lusitropy (relaxation) • Ionotropic state regulated by Ca concentration in cytoplasm, increased by beta stimulation (cAMP mediated) • Lusitropy governed by phosphorylation of phospholamban and Troponin I, which is partially regulated by beta stimulation.
  14. 14. Invasive assessment • Done by measurement of LV pressure with a high-fidelity micromanometer catheter • Calculates the peak instantaneous rate of LV pressure decline, peak dP/dt, and the time constant
  15. 15. Non-invasive Assessment Via Doppler echocardiography Flow velocities are measured across the mitral valve during diastole
  16. 16. End-diastolic Volume & Pressure
  17. 17. End Diastolic Volume (EDV) Volume at the end of diastole (end of ventricular filling). In a healthy heart this is directly proportional to venous return End Systolic Volume (ESV) Volume at the end of systole end of ventricular contraction Stroke Volume (SV) = EDV - ESV Ejection Fraction (EF) = SV/EDV Left Ventricular Volumes - Definitions Left ventricular norm for EF at Rest: approximately 62% Left Ventricular norms for Max Exercise: approximately 80%
  18. 18. End-diastolic volume • Normally 110-120 ml can increase to 180 ml
  19. 19. Preload • The initial length of the cardiac muscle fibre before contraction begins • can be equated to the end-diastolic volume • Clinically equated to the CVP when studying the RV or the PAOP when studying the LV
  20. 20. Starlings Law of the Heart and Contractility SV (left ventricular performance) Preload (venous return or EDV) u Contractility Normal Contractility d Contractility (heart failure) Preload X SV at Preload X - u contractility SV at Preload X – Normal cont. SV at Preload X - d contractility Starling’s Law: The greater the EDV (blood going in the heart), the more blood comes out of the heart The State of Myocardial Contractility determines the amount of blood (SV) that comes out of the heart at a given preload
  21. 21. Factors affecting preload • Venous return • Blood volume • Posture • Intra-thoracic pressure • Pericardial pressure • Venous tone • Heart rate & rhythm
  22. 22. Left Ventricular Pressure (mmHg) Volume (ml) Aortic Valve Closes ESV ESP Mitral Valve Closes EDV EDP Mitral Valve Opens Ventricular Filling Begins Aortic Valve Opens 120 6 40 140 Left Ventricular Pressure Volume Loop Isovolumic contraction SV Slope of dashed line: ventricular contractility
  23. 23. Left Ventricular Pressure (mmHg) Volume (ml) 120 6 40 140 Effects of an Increase in Preload on Left Ventricular Pressure Volume Loop u EDV u EDP u Ejection Pressure u SV
  24. 24. Left Ventricular Pressure (mmHg) Volume (ml) 120 6 40 140 Effects of an Increase in Afterload on Left Ventricular Pressure Volume Loop u ESV u ESP d SV
  25. 25. Diastolic dysfunction
  26. 26. Diastolic heart failure • Heart failure accompanied by predominant or isolated abnormality in diastolic function, this clinical syndrome is called. • symptoms and signs of heart failure, a preserved ejection fraction (EF), and abnormal diastolic function
  27. 27. Diastolic failure • predominantly occurs in patients over the age of 65 and • for unclear reasons is more common in women • Hypertension the most common underlying etiology. Other risk factors include diabetes mellitus, obesity, and bilateral renal artery stenosis
  28. 28. • Diastolic failure may also appear in elderly patients without any known predisposing • factors, possibly as an exaggeration of the normal stiffening of the heart with age,
  29. 29. Diastolic failure criteria • European society of cardiology 1. Signs/symptoms of CHF 2. Normal ?EF 3. Evidence of abnormal LV relaxation,filling,distensibility or stiffness
  30. 30. Left ventricular hypertrophy with and without dilation, viewed in transverse heart sections. Compared with a normal heart (center), the pressure-hypertrophied hearts (left) have increased mass and a thick left ventricular wall, while the hypertrophied, dilated heart (right) has increased mass and a normal wall thickness normal pressure-hypertrophied Volume hypertrophied,dilated
  31. 31. • Textbook of physiology Guyton & Hall • Ganong’s review of med. Physiology • Miller’s anesthesia 7th edn • Clinical anesthesiology Morgan & mikhail • http://123sonography.com/node/939 • http://circ.ahajournals.org/content/105/11/1387 .full • http://www.aafp.org/afp/2006/0301/p841.html