Incidence

Most common after rheumatic fever with a latency period of 10–25 years in under-developed countries to 20–40 years in developed countries.

Prevalence

• Women: 1.6%
• Men: 0.4% (1) [B]

• Risk for congestive heart failure, atrial fibrillation, thromboembolism, stroke, pulmonary hypertension, right-sided heart failure, and pulmonary edema.
• Mitral stenosis with atrial fibrillation increases the risk of stroke 7–15% per year (2) [B].
• Mild to moderate MS may be asymptomatic except during exertion, while severe MS symptoms occur at rest.
• LV dysfunction may occur in 30% of MS patients.

2-year mortality for infants with severe congenital MS is 40% (3) [B].

History

Commonly diagnosed after symptomatic exercising, during work up for diastolic or systolic CHF, or new onset atrial fibrillation.

Signs/Physical Exam

• Mid-diastolic murmur with opening S2 snap.
• Congestive heart failure (jugular venous distention, pitting edema, shortness of breath) and increased sympathetic tone (cool extremities, hypertension, etc.).
• In infants: Cyanosis, poor growth, shortness of breath.

Labs/Studies

• Basic metabolic profile: Electrolytes and kidney function aid with perioperative management and risk stratification (renal failure carries an increased risk of mortality).
• Complete blood count: Preoperative infection, hematocrit, and platelet counts adequate for surgery.
• Basic coagulation studies
• Chest X-ray: Active congestive heart failure.
• Transesophageal echocardiogram: Diagnosis and classification of disease severity and ventricular function.
• Cardiac catheterization: Cardiac function and pulmonary pressure evaluation.

Benzodiazepines may be useful to prevent anxiety and tachycardia.

• Risk for intraoperative stroke, acute congestive heart failure, myocardial infarction, and death, if increased risk, should be discussed.
• Access and monitoring line placement, if needed.

• Depends on the procedure; sedation, general anesthesia (endotracheal tube or laryngeal mask airway (LMA), and regional techniques may be utilized.
• Neuraxial techniques can result in a sympathectomy and decreased systemic vascular resistance that can impair coronary perfusion and decrease venous return (preload). It may be considered in mild or moderate MS. Epidurals allow for slow bolusing and time for fluid loading and treatment of hypotension with vasopressors. Carefully confirm appropriate anticoagulation status and profile before proceeding.

• Standard ASA monitors
• 5 lead EKG: Arrhythmia, ischemia
• Arterial line: Beat-to-beat BP monitoring
• Invasive monitors may be chosen based on the severity of MS and the surgical procedure.

Smooth, controlled induction to maintain vital signs within normal limits (heart rate and systemic vascular resistance) and allow time for treatment.

• Volatile anesthetics, intravenous, or a combination may be utilized. The specific drug is less important than the overriding goal: maintain normal sinus rhythm, systemic vascular resistance, contractility, and preload. Anesthetic agents can decrease vascular resistance and need to be titrated appropriately, co-administered with phenylephrine, or co-administered with other adjunctive agents (e.g., opioids) to decrease the total dosage.
• Adequate preload is essential to maintaining a stable cardiac output. Left ventricular filling is impaired with right ventricular and left atrial dysfunction thus predisposing to pulmonary edema.
• Maintenance of normal sinus rhythm is achieved by minimizing cardiac stress and avoiding pro-arrhythmic drugs.
  • Caution should be exercised when administering powerful chronotropes or anticholinergics. Tachycardia increases myocardial oxygen consumption, decreases diastolic time, and decreases LV filling.
  • Hypotension and hypertension should be managed with rate and rhythm in mind. All inotropes and vasopressors may be used with caution.
  • Ischemia usually occurs with arrhythmia, tachycardia, or hypotension, and the treatment usually lies in the reversal of those conditions.
• Hyperoxia, hypocarbia and pulmonary vasodilators may improve pulmonary resistance.

• Avoid tachycardia and hypotension; consider having rapid onset and short-acting beta blockers and antihypertensives immediately available.
• Standard extubation criteria.