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Anesthetic-Considerations-Aortic-Stenosis

Anesthetic Considerations: Hemodynamic Goals (“CRRAP Goals”) for Patients with Aortic Stenosis Undergoing Non-Cardiac Surgery CRRAP Goals: Contractility, Rate, Rhythm, Afterload, Preload Pathophysiology Driving Anesthetic Management Hemodynamic Anesthetic Intervention (CRRAP) Goals Author: Ryan Brenneis Reviewers: Stephen Chrusch Hannah Yaphe Yan Yu* Karl Darcus* * MD at time of publication Aortic stenosis = Narrow aortic valve opening Notes: -Cardiac Output = Heart Rate x Stroke Volume -Stroke volume has 3 determinates: 1. Contractility 2. Afterload 3. Preload If the patient’s heart cannot ↑ contractility to maintain cardiac output... ↑ resistance to forward blood flow àheart must ↑ its contractility (↑ the forcefulness of its contractions) to overcome this resistance Applying ↑ force over time causes left ventricle to undergo concentric hypertrophy Contractility deteriorates over time Heart rate must compensate for maintaining cardiac output Coronary Perfusion Pressure = Diastolic BP (DBP) – Left Ventricular End Diastolic Pressure (LVEDP) ↑ cardiac muscle massà↑ myocardial metabolism and oxygen demand ↑ left ventricular wall stiffnessà↓ LV filling while relaxed (diastolic dysfunction) Intraoperative ↓ in contractility compromises cardiac output Bradycardia ↓ cardiac output Tachycardia ↓ filling time of left ventricle (↓ preload) Coronary perfusion occurs during diastole Coronaries require a high DBP to maintain perfusion Tachycardia ↓ perfusion time Hypotension ↓ coronary perfusion pressure Possible myocardial ischemiaà ↓ blood pumped into vessels 40% of LV preload supplied from atrial kick Loss of atrial kick with arrhythmias à↓ cardiac output Note: Aortic stenosis severity (see slide on aortic stenosis) and the type/risk of surgery guide the hemodynamic consequences and need for intervention Adequate intravascular volume required to passively fill stiff ventricle Contractility ↓ use of negative inotropic Maintain drugs, e.g. calcium channel contractility blockers (“Inotrope”: drug that alters heart’s contractility) Rate Keep heart rate above 60 bpm Keep heart rate below 80 bpm Consider transcutaneous pacing, anticholinergics, & sympathetic agonists ↑ anesthetic depth, consider beta blocker (e.g. Esmolol) Afterload Maintain a Mean Arterial Pressure >70mmHg Consider sympathomimetic drugs to treat hypotension Monitor blood pressure closely via arterial line Consider increasing anesthetic depth for severe hypertension Rhythm Maintain Sinus Rhythm Consider presurgical placement of defibrillator pads & crash cart Amiodarone ready & available during operation, to terminate any arrhythmias Preload Maintain Euvolemia Possible use of transesophageal echo to monitor preload Ensure adequate venous access- consider central venous catheter and large bore IV’s Legend: Pathophysiology Mechanism Goal Anesthetic Intervention Published October 25, 2020 on www.thecalgaryguide.com