Mitral Stenosis: Anesthesia and Care Guide

Mitral Stenosis: Anesthesia and Care Guide

Mitral stenosis is a condition where the mitral valve narrows, obstructing blood flow from the left atrium to the left ventricle. This article provides information on mitral stenosis, including severity, pathophysiology, risks, anesthesia priorities, and essential considerations.

# Mitral Stenosis Classification

• Normal valve area: 4-6 cm2.

• Area > 2.5cm2: patients are often asymptomatic.

Classification based on valve area on echocardiogram:

• Mild stenosis: 1.5-2.5 cm2.

• Moderate stenosis: 1-1.5 cm2.

• Severe stenosis: < 1 cm2.

Classification based on pressure gradient across the mitral valve:

• Mild stenosis: < 5 mmHg.

• Moderate stenosis: 5-12 mmHg.

• Severe stenosis: > 12 mmHg.

# Pathophysiology

Upstream:

• Left atrial dilatation: leading to atrial fibrillation, thrombus formation.

• Pulmonary artery hypertension (PAH): due to blood stagnation in the lungs.

• Pulmonary congestion: reduced lung elasticity, leading to increased respiratory effort.

• Pulmonary hypertension (PH): leading to right heart failure, tricuspid regurgitation.

Downstream:

• Reduced stroke volume: due to reduced blood flow through the stenosis, atrial fibrillation, right ventricular dilatation.

• Prolonged diastole: to ensure adequate ventricular filling.

# Risks Related to Anesthesia

• Arrhythmias.

• Pulmonary artery hypertension (PAH).

• Right ventricular ischemia.

• Reduced cardiac output.

# Anesthesia Priorities

• Maintain sinus rhythm.

• Stabilize heart rate: avoid tachycardia, which reduces diastole, impairing left ventricular filling.

• Maintain adequate blood pressure.

• Avoid increasing PH: such as acidosis, hypoxia, hypothermia.

• Adequate fluid resuscitation: but be cautious to avoid increasing PH, right heart failure, and PAH.

• If systolic blood pressure <= PH: risk of right ventricular ischemia.

# Anesthesia Choice

• General anesthesia (GA): indicated, considering the following:

• Medications:

• Digoxin: use until the day of surgery to maintain sinus rhythm and avoid tachycardia.

• Diuretics: use until the day of surgery to prevent PAH.

• Contraindications: atropine, ketamine, pavulon (induce tachycardia).

• Treatment for sinus tachycardia: Esmolol (caution in patients with left ventricular failure).

• Treatment for rapid arrhythmias: Cedilanide (small doses).

• Electrical shock: ineffective in chronic atrial fibrillation (1J/Kg).

• Hypotension:

• Fluid resuscitation: cautious of PAH.

• Ephedrine: acceptable due to minimal tachycardia induction.

• Inotropes: often ineffective.

• Anesthetics:

• Succinylcholine: contraindicated in patients taking Digoxin.

• Thiopental, morphine, rocuronium, atracurium, vecuronium: safe.

• Awakening phase: risk of tachycardia, changes in blood volume.

• Positioning: avoid positions increasing venous return, avoid pulmonary overload.

• Spinal anesthesia (SA): rarely indicated for patients with severe stenosis due to the risk of reducing ventricular filling.

• Peripheral nerve block: no contraindications.

• Local anesthetics containing Adrenaline: may induce tachycardia, reduce ventricular filling.

# Considerations for General Anesthesia

• Digoxin: use until the day of surgery to maintain sinus rhythm and prevent tachycardia.

• Diuretics: use until the day of surgery to prevent PAH.

• Contraindicated drugs inducing tachycardia: atropine, ketamine, pavulon.

• In case of sinus tachycardia: manage with Esmolol (short-acting, cautious in patients with left ventricular failure).

• In case of hemodynamically significant rapid arrhythmias: treat with Cedilanide (small doses).

• Electrical shock: less effective in patients with chronic atrial fibrillation (1J/Kg).

• If hypotension occurs during surgery:

• Adequate fluid resuscitation: cautious of PAH.

• Ephedrine is acceptable due to minimal tachycardia induction.

• Inotropes are often ineffective.

• Using Succinylcholine in patients on Digoxin: may cause arrhythmias.

• Thiopental, morphine, rocuronium, atracurium, vecuronium: safe.

• Awakening phase: high risk due to tachycardia, changes in blood volume.

• Avoid positions increasing venous return: prevent pulmonary overload.

# Conclusion

Anesthesia for patients with mitral stenosis requires careful management and close monitoring. Always pay attention to heart rate, blood pressure, PH, and ventricular filling status to ensure patient safety throughout the surgical procedure.