Paravalvular Leak

Paravalvular leak is abnormal regurgitant flow through a defect between the sewing ring or frame of a prosthetic valve and the native annulus, as distinct from flow through the valve itself. It occurs after surgical and transcatheter valve replacement.

Small, mild leaks are detected on echocardiography in a considerable minority of surgical valves, and clinically significant leaks occur in about 1 to 5%, more often in the mitral than the aortic position.

After transcatheter aortic valve implantation, moderate or severe leak is less common with newer devices (about 1 to 5%), while mild leak is frequent.

Causes are suture dehiscence or tissue fragility from annular calcification, endocarditis with annular abscess, a rigid or heavily calcified annulus, valve malposition or undersizing, and early surgical technique. Late causes are infection, tissue degeneration and progressive dehiscence.

Pathophysiology. Regurgitation through the gap causes chronic volume overload of the ventricle and congestion. A small defect with a high velocity jet damages red cells by shear stress, causing mechanical haemolysis with fragmented cells (schistocytes), anaemia, and iron or folate loss.

The leak can enlarge over time and raises the risk of endocarditis.

• Mild leaks are silent.
• Heart failure: dyspnoea, orthopnoea, oedema, fatigue.
• Haemolytic anaemia: fatigue, pallor, jaundice, dark urine, and the need for repeated transfusion.
• A new or changed regurgitant murmur: diastolic at the left sternal edge in the aortic position, apical systolic in the mitral position. Mechanical click may be preserved.
• Fever and embolic phenomena when infection is present.

Red flags.

• Fever, positive blood cultures, or new regurgitation (endocarditis, abscess)
• Rapid worsening heart failure or pulmonary oedema
• Haemolysis with transfusion dependence or falling haemoglobin
• Rocking valve (motion of more than 15 degrees) on echocardiography
• Severe leak with ventricular dilatation or falling ejection fraction
• Embolic events

• Transthoracic echocardiography. Colour Doppler jet outside the sewing ring, new ventricular dilatation, rising ventricular volumes, and high flow through the prosthesis (raised gradient). Severity by the circumferential extent of the leak: under 10% of the sewing ring is mild, 10 to 29% is moderate, and 30% or more is severe. Also use vena contracta (aortic: over 6 mm is severe; mitral: 6 mm or more), regurgitant volume of 60 mL or more, effective regurgitant orifice area (aortic: 0.3 cm2 or more; mitral: 0.4 cm2 or more), holodiastolic flow reversal in the descending aorta (aortic), and pulmonary vein systolic flow reversal (mitral).
• Transoesophageal echocardiography with three dimensional imaging. Essential for locating, sizing and shaping the defect and for planning closure. It also looks for vegetation or abscess.
• Cardiac CT or MRI for complex anatomy and quantification of regurgitation.
• Blood tests for haemolysis. Haemoglobin, reticulocytes, LDH, haptoglobin, bilirubin, blood film (schistocytes), direct antiglobulin test (negative), ferritin, B12 and folate.
• Blood cultures (3 sets) with any fever or raised inflammatory markers.

Differential diagnosis.

• Transvalvular regurgitation, including the small physiological closing and leakage jets of mechanical valves
• Prosthetic valve thrombosis, pannus, or bioprosthetic degeneration
• Endocarditis with annular abscess
• Other haemolytic anaemias (autoimmune, hereditary)
• Anaemia from iron deficiency, blood loss or nutritional deficiency
• Heart failure from left ventricular dysfunction
• Regurgitation of another valve

• Mild leak without symptoms or haemolysis: observation. Endocarditis prophylaxis for dental procedures: amoxicillin 2 g orally as a single dose 30 to 60 minutes before. For penicillin allergy, azithromycin 500 mg or doxycycline 100 mg orally as a single dose.
• Heart failure: furosemide 40 mg orally once daily in the morning, increased to 80 to 120 mg daily as needed (higher doses in renal impairment under specialist care), with sodium, potassium and creatinine monitoring. Treat blood pressure and atrial fibrillation.
• Haemolysis:
  • Ferrous sulphate 200 mg (65 mg elemental iron) orally once daily or on alternate days (reduce frequency if gastrointestinal intolerance), once iron deficiency is shown. Avoid if ferritin is high.
  • Folic acid 5 mg orally once daily while haemolysis continues.
  • Transfuse for symptomatic anaemia, haemoglobin under 70 g/L (under 80 g/L with cardiac disease).
• Indications for closure: NYHA class II to IV from moderate or severe leak, haemolysis needing transfusion or causing symptoms or iron loss, or severe leak with ventricular dilatation or falling ejection fraction. Exclude endocarditis first. Active endocarditis with abscess needs surgery.
• Percutaneous closure. Vascular plugs or occluders delivered through transseptal, transapical or retrograde aortic routes, in a centre with structural expertise. Check that the device does not impede mechanical leaflet motion. Technical success is about 80 to 90%, and complete elimination of the leak is less frequent. Risks are residual leak, device embolisation, worsening haemolysis, stroke, vascular injury and tamponade. After closure continue the existing anticoagulation for a mechanical valve and add aspirin 75 to 100 mg orally once daily for 3 to 6 months (practice varies).
• Surgical redo with repair or replacement of the valve when percutaneous closure is unsuitable or fails. Reoperation risk is higher than the primary operation.
• Endocarditis: give prolonged intravenous antibiotics after blood cultures, starting with vancomycin 15 to 20 mg/kg every 8 to 12 hours (maximum 2 g for each dose, trough 15 to 20 mg/L, longer interval in renal impairment) until the organism is known and then directed by sensitivities for 4 to 6 weeks, with early surgery for abscess, dehiscence or heart failure.

Special groups. Pregnancy with a significant leak and a mechanical valve is high risk. Plan with the heart team before conception. Women who need warfarin or heparin follow the specialist plan for mechanical valves in pregnancy.

Monitoring. Haemoglobin, reticulocytes, LDH and ferritin every 1 to 3 months while haemolysis continues. Echocardiography at 1, 6 and 12 months after closure, then yearly. Echocardiography every 6 to 12 months for moderate leaks managed conservatively.

Referral and escalation. Refer to a heart team with structural intervention expertise. Urgent for fever, acute decompensation or refractory haemolysis.