The daily educational pearl – Mitral stenosis

For those sitting exams soon. And for those who haven’t opened Talley & O’Connor’s for a while.

Mitral stenosis

Normal surface: 4 – 6 cm2; patients become symptomatic when surface < 2 cm2 and life expectancy (without surgical treatment) is 2 – 5 years after onset of symptoms

Causes:

– rheumatic fever – onset ~ 2 yrs after the acute episode

– congenital – parachute valve

Symptoms:

– dyspnoea / orthopnoea / paroxysmal nocturnal dyspnoea

– haemoptysis; fatigue (pulmonary hypertension)

– dysphonia / dysphagia if grossly enlarged left atrium compressing the left recurrent laryngeal nerve or oesophagus

Once right ventricular failure occurs – ascites, peripheral oedema.

10 – 15 % of patients have chest pain due to acute right ventricular pressure overload or due to emboli from the left atrium into the coronary circulation.

Signs:

tachypnoea

atrial fibrillation

mitral facies / peripheral cyanosis in severe cases

tapping apex beat; right ventricular heave

prominent a wave (JVP) if pulmonary hypertension is present (but lost if patient is in atrial fibrillation)

loud S1; loud P2 (if pulmonary hypertension present)

low-pitched rumbling diastolic murmur (best auscultated over the apex with the bell and the patient in left lateral decubitus; louder after exercise)

ECG findings:

P mitrale

– right axis deviation in severe disease

Severe mitral stenosis:

– symptoms / signs of pulmonary hypertension

– early opening snap

– long diastolic murmur

– decreased pulse pressure

– valve area < 1 cm2 on echo

– presence of pulmonary or tricuspid regurgitation

 

Management precautions:

– increased cardiac output or heart rate will increase the flow across the valve and the transvalvular pressure gradients – AVOID tachycardia and both hypovolaemia and fluid overload

– avoid ketamine

– cautious use of nitrous oxide  (Entonox) as it can increase the pulmonary vascular resistance

 

 

 

 

 

 

 

 

 

 

 

 

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