Mitral stenosis

Overview

🎯

The exam signal here tests ADPKD's cardiac association - mitral valve prolapse - not classical mitral stenosis management. Keep both in mind.

Presentation

•Dyspnoea - exertional initially, progressing to orthopnoea/PND

•Palpitations - often first presentation of AF

•Haemoptysis - dilated pulmonary veins or pulmonary oedema

•Systemic emboli - stroke/peripheral ischaemia from LA thrombus (especially in AF)

•Loud S1 - thickened leaflets snap shut forcefully

•Opening snap - early diastole after S2; shorter S2-OS interval = more severe stenosis (higher LA pressure)

•Mid-diastolic rumbling murmur - low-pitched, bell at apex, left lateral decubitus; presystolic accentuation in sinus rhythm

•Tapping apex beat - palpable non-displaced S1

•Malar flush - bilateral cheek erythema from low cardiac output

•Irregularly irregular pulse - AF from LA dilatation

💡

Shorter S2-opening snap interval = more severe stenosis. This is the inverse of what students expect.

Investigations

🥇 First-line

•transthoracic echocardiography (TTE) - measures mitral valve area (MVA), mean pressure gradient, pulmonary artery pressure; Wilkins score for PMC suitability

🏆 Gold standard

•transoesophageal echocardiography (TOE) - LA appendage thrombus; mandatory before PMC and after embolic episode

•ECG: P-mitrale (broad bifid P wave in II), AF, RV hypertrophy

•CXR: double shadow at right heart border, Kerley B lines, upper lobe diversion, carina splaying

Management

•Pulmonary congestion: furosemide - reduces symptoms

•Rate control in AF: bisoprolol or verapamil - slows HR, prolongs diastole, improves LV filling

•Anticoagulation in AF: warfarin - for all patients with mitral stenosis + AF, prior embolism, or LA thrombus

⚠️

Warfarin (NOT DOACs) is the anticoagulant of choice in rheumatic mitral stenosis with AF. DOACs are not recommended in this setting - a key distinction from non-valvular AF.

Complications

•AF - up to 40% of patients; acutely worsens haemodynamics by reducing diastolic filling time

•Systemic thromboembolism - stroke most feared; LA appendage is usual thrombus site

•Pulmonary hypertension - reactive (reversible) then obliterative (irreversible)

•RV failure - peripheral oedema, ascites, hepatomegaly

•Recurrent pulmonary oedema - precipitated by tachycardia (pregnancy, sepsis, exercise) shortening diastole

ADPKD and Mitral Valve Disease

•Mitral valve prolapse - the key cardiac association with autosomal dominant polycystic kidney disease (ADPKD)

•Other cardiovascular associations: mitral/tricuspid incompetence, aortic root dilation, aortic dissection

•ADPKD is associated with hypertension (not hypotension) - mediated by RAAS over-activation from growing cysts

•ADPKD is associated with haematuria (not proteinuria) - from rupture of a cyst into the collecting system

⚠️

ADPKD is NOT associated with aortic stenosis, bicuspid aortic valve, dilated cardiomyopathy, or HOCM - common distractors in exam questions.

Mitral Stenosis - Key Background

•Dominant cause: rheumatic heart disease (Group A streptococcal pharyngitis → immune-mediated leaflet thickening, commissural fusion)

•Pathophysiology chain: narrowed orifice → ↑ LA pressure → LA dilatation → pulmonary venous congestion → pulmonary hypertension → RV failure

•LA dilatation → AF → loss of atrial kick → ↑ thrombus risk in LA appendage → systemic embolism