Valvular Heart Disease Student Notes PDF

VALVULAR HEART DISEASE NRAN 80413 SPRING 2024 RON ANDERSON, M.D. 1 VALVULAR HEART DISEASE Growing practice – Despite marked decrease in rheumatic heart disease – Aging population – Innovations being made in surgical intervention Variable physiologic and hemodynamic aberrations influenced by anesthet...

VALVULAR HEART DISEASE NRAN 80413 SPRING 2024 RON ANDERSON, M.D. 1 VALVULAR HEART DISEASE Growing practice – Despite marked decrease in rheumatic heart disease – Aging population – Innovations being made in surgical intervention Variable physiologic and hemodynamic aberrations influenced by anesthetic intervention Natural history of disease is important to determine: – Timing of intervention – Anesthetic management Maintenance of heart rate/ pacing Inotrope usage Vasodilators/vasoconstrictors 2 PRESSURE-VOLUME LOOPS 3 KAPLAN AFTERLOAD MISMATCH AFTERLOAD STRESS PRELOAD RESERVE 4 KAPLAN VENTRICULAR COMPLIANCE Acute increases in volume (e.g. acute AI) produce marked increases in LVEDP Chronic change tends to shift the curve to the right such that higher volumes are tolerated In chronic pressure overload there is: – An inverse linear relationship between hypertrophy and compliance – Impaired ventricular relaxation 5 KAPLAN MEASURES OF CONTRACTILITY Contractility = ability to generate force at a given preload Isovolumetric Indices (Vmax, dP/dT) – Relatively insensitive to loading conditions – Poor reflection of basal contractility Ejection Phase Indices – Directly proportional to preload – Vary inversely with afterload – Unreliable in most valvular disease End Systolic Pressure Volume Relationship (ESPVR) – More precise estimate of contractility – Independent of preload 6 MEASURES OF CONTRACTILITY 7 END SYSTOLIC PRESSURE VOLUME RELATIONSHIP GROUP EF A >0.6 B 0.41-0.59 C 10 1.6 – 2.0 1.0 – 1.5 < 1.0 Approximately 1/3 of patients with severe disease develop atrial fibrillation LA distention and A Fib increase risk of thromboembolic events 45 MITRAL STENOSIS 46 Preload reserve is decreased LVEDV and LVEDP are reduced Stroke volume is reduced MILLER PROCEDURES AND TIMING Patients with severe symptoms or stenosis, or significant pulmonary HTN are operated early Mild stenosis with few or no symptoms can be managed conservatively Procedures – Percutaneous mitral commissurotomy (PMC) aka Percutaneous balloon valvotomy – Open commissurotomy – Valve repair or replacement 47 ANESTHETIC MANAGEMENT OF MITRAL STENOSIS PRIMARY GOALS Control ventricular rate Normal to increased preload Normal afterload Monitoring PAC – Trends may be useful, but won’t accurately reflect LV volume TEE Avoid: – Tachycardia – Pulmonary vasoconstriction 48 MITRAL STENOSIS Sedation – Valuable for avoiding tachycardia, but avoid oversedation leading to hypoventilation Induction – Most are acceptable with the exception of ketamine – Opiod induction if needed Maintenance – Balanced technique usually with narcotic and low-dose volatile – + Nitrous oxide – concerns with pulmonary HTN 49 MITRAL VALVE PROLAPSE Affects 1-2.5% of population More commonly in young women Etiology May be related to: – – – – – Thyrotoxicosis Marfan syndrome SLE Myocarditis Rheumatic disease 50 MITRAL VALVE PROLAPSE Definition Valve leaflet prolapse > 2mm above annulus Things which worsen prolapse Increased contractility Decreased SVR Upright posture – Head up or sitting position for surgery Anesthetic Management Similar to mitral regurgitation Maintain adequate intravascular volume 51 HEART MURMURS Systolic Aortic Stenosis Mitral Regurgitation Diastolic Aortic Regurgitation Mitral Stenosis Aortic Best heard at right 2nd intercostal space Radiation to neck Mitral Best heard at apex Regurg radiation to axilla Stenosis – little radiation 52 ANTICOAGULATION WITH A PROSTHETIC VALVE General guidelines for patient with a mechanical valve Typically managed with low-dose ASA and a vitamin K antagonist. Desired INR varies but typically >2 – Discontinuing anticoagulation also varies considerably, but “generally”: Discontinue vitamin K antagonist 3-5 days preop Initiate heparin or LMWH when INR falls to subtherapeutic Discontinue heparin day of or day prior to surgery 53 SOURCES Anesthesia and Coexisting Disease. Hines, Marschall. 8th Edition. 2022 Kaplan’s Cardiac Anesthesia. Kaplan. 7th Edition. 2016 54