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Dr. Nitish parmar

AORTIC STENOSIS & REGURGITATION Pathophysiology & Anaesthetic consideration for non-cardiac surgery. Dr. Nitish parmar. University College of Medical Sciences & GTB Hospital, Delhi. Objectives. Definition Etiology Pathophysiology Preoperative evaluation Anaesthetic management.

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Dr. Nitish parmar

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  1. AORTIC STENOSIS & REGURGITATIONPathophysiology & Anaesthetic consideration for non-cardiac surgery Dr. Nitishparmar University College of Medical Sciences & GTB Hospital, Delhi

  2. Objectives Definition Etiology Pathophysiology Preoperative evaluation Anaesthetic management AS/AR

  3. Normal P-V loop esv edv

  4. Preload reserve and afterload mismatch

  5. Laplace law Wall tension = P x R / 2h P= pressure R = radius h= wall thickness Increase wall tension stimulates concentric hypertrophy of LV

  6. Aortic stenosis (AS) • Aortic stenosis refers to obstruction of flow at the level of the aortic valve  • Restricted systolic opening of the valve, with a mean transvalvular pressure gradient of at least 10 mm Hg. • Normal aortic valve area is 2.5-3.5cm² • Haemodynamically significant obstruction occurs at valve area of < 1 cm2

  7. Etiology

  8. Etiology

  9. Pathophysiology Chronic pressure overload Peak systolic wall stress Parallel sarcomere replication Concentric hypertrophy ( no increase in the LV size )

  10. Pathophysiology

  11. AORTIC STENOSIS LV outflow obst. ↑LV systolic P ↑ LVET ↑ LV diastolic P ↓ AoP ↑ LV mass ↑ Myocardial O2 consumption ↓ Diastolic time Myocardial ischemia LV Dysfunction LV Failure

  12. Contd… • Increased diastolic stiffness magnifies the importance of atrial systole to ventricular filling • Hypertrophied ventricle is highly sensitive to ischemia • Increase myocardial oxygen demand • Decreased coronary perfusion gradient • Circulatory abnormalities in myocardium • Decreased capillary density • Abnormal thickening of coronary arterioles

  13. Preoperative evaluation angina dysopnea syncope

  14. Angina Myocardial O2 mismatch • ↑Demand •  due ventricular hypertrophy • ↓Supply • ↑ LVEDP • Hypotension • Abnormal coronary circulation • ↓capillary density • Thickened arterioles

  15. Dyspnea Systolic and diastolic dysfunction of left ventricle  pulm capillary hydrostatic pressure transudation of fluid into interstitial space  lung compliance  WOB dyspnea

  16. Syncope • fall in CO d/t arrythmia fixed CO state • Other symptoms • Symptoms of LVF occur only in the advanced stages of the disease • When AS and MS coexist   volume produced by MS   gradient across the AV  masking of clinical findings by AS

  17. signs • Pulse: small volume, pulsusparvus et tardus • BP – normal or low • PP – low, due to fall in SBP when SV  in late stages

  18. Signs • Cardiac apex – heaving • S1 – normal / soft • S2 – paradoxical split in late stages • Palpable S4 • Aortic ejection click • Ejection mid systolic murmur

  19. Ecg LVH LV- strain pattern

  20. CXRProminent ascending aortarounding of left ventricular apexcalcified valves

  21. Echo Asessment of severity However when cardiac output is low severe stenosis may be present with lower transvalvular pressure gardient and lower jet velocity

  22. Non cardiac surgery elective emergency Proceed with medical optimization and high risk severe Mild to moderate GA/spinal /epidural

  23. SEVERE asymptomatic symptomatic Risk of surgery Risk for AVR Low/mod High Low High Risk for AVR High Low Consider valvuloplasty High risk stratification Proceed AVR Consider valvuloplasty High risk stratification

  24. Hemodynamic goals

  25. Monitoring • Standard non-invasive • ECG : 5 lead including lead II & V5 • HR • NIBP • Pulse-oxymetry • Capnograph • Temperature • Apply defibrillator pads beforehand

  26. Monitoring • Invasive monitoring • IBP • CVP/PAC ?? • Echocardiography (TEE)

  27. Premedication Aim • To decrease anxiety & any associated likelihood of adversecirculatory responses produced by tachycardia

  28. Intraoperative management

  29. Opioids

  30. Intra-operative management

  31. Non-opioid induction agents

  32. Muscle Relaxants

  33. Inhalational agents

  34. Post-operative management Majority of the cardiac events in non cardiac surgery occur in postoperative period Monitoring Oxygen Pain relief: multimodal including neuroaxialopioids Intravenous fluids

  35. Regional anesthesia • Technique should be applied cautiously • Mild to moderate aortic stenosis: can be used • Severe : contraindicated • Epidural anesthesia is preferable to spinal anesthesia • Spinal with opioid • Caution with anticoagulants

  36. Prosthetic valves Prosthetic valves • Mechanical • Greater durability • Needs life long anticoagulation • More complications • Preferred in younger patients (<65) • Bioprosthetic • Less durable • No need for anticoagulation • Lesser complications • Preferred in older patients who donot need anticoagulation

  37. Complications • Valve thrombosis • Systemic embolization • Structural failure • Hemolysis • Paravalvular leak • Endocarditis

  38. Endocarditis prophylaxis • Dental procedures • Procedures involving incision of respiratory mucosa (adenoidectomy, tonsillectomy) • Incision on infected skin, musculoskeletal tissue • Cystoscopy if results of urine culture not known

  39. Antibiotics

  40. Anticoagulation Discontinue warfarin at least 5 day before Sx Bridge with SC LMWH or IV unfractionated heparin (36 hrs later) Asses INR 1-2 days before Sx If >1.5 1-2 mg oral vit K

  41. Anticoagulation Patient receiving SC LMWH-stop 24 hrs prior Patient receiving UF heparin-stop 4 hrs prior Post operative Emergent procedure: treat with 2.5-5.0 mg IV vitamin K For faster reversal: FFP • Major Sx • Minor Sx • Begin after 48-72 hrs • Begin after 24 hrs

  42. Anticoagulation Start the patient back on oral warfarin Monitor PTT and aPTT on daily basis Attain INR of 2.5-3.0 for 2-3 days Stop heparin and continue warfarin

  43. Neuraxial anesthesia • Neuraxial block should be delayed for 12 hrs (prophylactic) and 24 hrs (therapeutic) after last dose of LMWH • Removal of epidural catheter should take place 12 hrs after last dose • Subsequent dosing delayed for 2 hrs

  44. Preoperative • Echo • Ejection fraction • Normal functioning of valve • Paravalvular leaks • Vegetations • Clots • In a patients with prosthetic valves rest of the anesthetic concerns are similar to a regular non VHD patient

  45. Aortic regurgitation incompetence of the aortic valve, in which a portion of the left ventricular forward stroke volume returns to the chamber during diastole. 

  46. Etiology In approximately two third of the patients with valvular AR, the disease is rheumatic in origin • Acute • IE • Trauma • Aortic dissection • Chronic • Abnormalities of • AV (congenital bicuspid valve) • Aortic root – syphilis, cystic medial necrosis • Marfan’s syndrome • Rheumatic arthritis

  47. Pathophysiology LV cannot dilate sufficiently  Effective SV   Sudden  in LVEDP  Transmitted to pulm circ.  Acute pulm congestion

  48. Contd.. Chronic overload ↑LVEDV ↓ Series replication of sarcomere ↓ Chamber enlargement ↓ Eccentric hypertrophy ↑ wall stress ↓ Concentric hypertrophy cardiomegaly (mild)

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