Mitral regurgitation

anesthetic goals in mitral regurgitation

1. Mitral regurgitation & anesthetic considerations

2. INTRODUCTION: Mitral regurgitation is defined as an abnormal reversal of blood flow from the left ventricle to the left atrium. It is caused by disruption in any part of the  mitral  valve apparatus

3. Etiology: Acute Endocarditis Papillary muscle rupture (post-MI) Trauma Chordal rupture leaflet flail (MVP) Chronic Myxomatous (MVP) Rheumatic fever Endocarditis (healed) Mitral annular calcification Congenital (cleft, AV canal) Ischemic (LV remodeling) Dilated cardiomyopathy

4. Pathopysiology : basic hemodynamic derangement decrease in forward left ventricular stroke volume & cardiac output. A portion of every stroke volume is regurgitated through the incompetent mitral valve back into the left atrium results in left atrial volume overload& pulmonary congestion. Patients with a regurgitant fraction of more than 0.6 (60%)are considered to have severe mitral regurgitation.

5. The fraction of left ventricular stroke volume that regurgitates into the left atrium depends on the size of the mitral valve orifice heart rate, which determines the duration of ventricular ejection pressure gradients across the mitral valve. Pharmacologic interventions that increase or decrease systemic vascular resistance have a major impact on the regurgitant fraction in patients with mitral regurgitation.

6. Clinical features: Symptoms Dyspnoea - pulmonary venous congestion Fatigue - low cardiac output Palpitation Oedema , ascites - right heart failure Signs Atrial fibrillation/flutter Cardiomegaly Apical pansystolic murmur ± thrill Soft S1, apical S3 Signs of pulmonary venous congestion- Crepitations , pulmonary oedema , effusions Signs of pulmonary hypertension and right heart failure

7. Severity of mr : Method MILD Moderate Severe Regurgitant volume 30-40 mL 40-60 mL >60 mL Regurgitant fraction 10%-30% 30%-50% >55% Regurgitant orifice area <0.2 cm 2 0.3-0.4 cm 2 >0.4 cm 2

8. Management: Medical Diuretics Vasodilators . ACE inhibitors Digoxin - AF Anticoagulants – AF Antibiotic prophylaxis - IE Surgical valvuloplasty with moderate to severe symptoms regurgitant volume 30-60%

9. Anesthetic goals: Primary goal - maintaining forward systemic flow & reduction regurgitant fraction HR - high-normal range -80 to 100 beats/min Avoid bradycardia - ↑ duration of systole prolongs regurgitation Rhythm- maintain sinus rhythm Preload - Maintain or slightly increase- elevated preload cause an ↑ regurgitant flow- low preload inadequate cardiac output Afterload - Decrease to improve forward cardiac output-avoid sudden increases in SVR Contractility - Maintain or increase to decrease left ventricular volume

10. LV PRELOAD HR RHYTHM CONTRACTILITY SVR PVR Maintain or higher rate Maintain orhigher rate Maintain sinus rhythm Maintain ↓ ↓

11. Induction of anesthesia: With an intravenous induction drug. Dosing adjusted to prevent ↑SVR & ↓ HR muscle relaxant - Pancuronium modest ↑ in heart rate Spinal & epidural anesthesia are well tolerated, provided bradycardia is avoided.

12. Maintenance of anesthesia: Volatile anesthetics- isoflurane , desflurane & sevoflurane - choices for maintenance of anesthesia. Severely compromised myocardium - opioid -based anesthetic is preferred - minimal myocardial depression. Mechanical ventilation - adjusted to maintain near-normal acid-base and respiratory parameters. The pattern of ventilation - provide sufficient time between breaths for venous return .