About the Condition
Valve hemolysis occurs when red blood cells (RBCs) are mechanically fragmented when they pass through a prosthetic heart valve with a paravalvular leak or far less commonly through a stenotic native valve.
Hemolytic anemia is anemia caused by premature destruction of red blood cells as defined by:
- Otherwise unexplained anemia.
- Signs of accelerated RBC production in the bone marrow (e.g., high reticulocyte count).
- Signs of RBC destruction (e.g., elevated unconjugated bilirubin, lactate dehydrogenase [LDH], low haptoglobin).
Sub-clinical hemolysis is used to describe patients who meet the last two criteria but do not have anemia. In these patients, the bone marrow adequately compensates for the hemolysis, maintaining a normal hemoglobin.
The incidence of hemolysis in patients with cardiac prostheses varies widely according to the device type and its indwelling time.
|Valve||Subclinical hemolysis||Hemolytic anemia||Comments|
|Native valve||Rare||Rare||Stenotic aortic > mitral valve|
|Old generation mechanical valves, e.g., caged-ball prostheses||23-92%||up to 15%||Mitral valve > aortic valve; Diagnosis several years after implantation|
|Modern mechanical valve designs.||18% to 51%||<1%||Hemolytic anemia is an infrequent finding in absence of prosthesis malfunction|
|Tissue valves||5% to 10%||<1%||Less common than with prosthetic valves|
|Transcatheter valve replacement|
|TAVR||15%-30%||Rare||Occurs within months of implantation; degree of|
|TMVR||Scant data||Scant data|
|Valve repair||Rare||Rare||Most patients present with signs of hemolysis within 3 months from the operation|
Mechanical damage to the RBCs due to increased shear stress as the cells pass through an abnormal channel created by:
- Structural deterioration of valve, for example severe native aortic stenosis.
- Paravalvular leak (most common cause)
- Turbulent flow through the valve or between the sewing ring and the native ring (incomplete apposition of the prosthetic sewing ring and the native annulus).
- May result from suture dehiscence due to:
- Heavy annular calcifications
- Suboptimal surgical technique
- Tissue friability
|Native valve||High blood flow velocity|
through a stenotic valve (especially aortic)
|Surgical valve||PVL (most common), SVD, PPM, endocarditis, leaflet thrombosis|
|TAVR||PVL, PPM, increased red cell shear stress in the sinuses due to residual native valve fissuring and balloon‐induced endothelial denudation|
|TMVR||PVL due to incomplete sealing, device undersizing, or progressive left ventricular remodeling|
|Valve repair||Ring dehiscence, residual eccentric or para‐ring regurgitation, protrusion of suture material, free‐floating chordae in hyperdynamic left ventricle|
Note: Hemolytic anemia causes an increase in cardiac output, which, in turn, worsens the rate of hemolysis, thus creating a vicious circle.
Consider the diagnosis of valve hemolysis in a patient with:
- Cardiac prosthesis and unexplained anemia.
- Positive screen for hemolysis:
- Decreased serum haptoglobin
- Presence of schistocytes on peripheral smear.
- Symptoms of congestive heart failure (also caused by prosthetic valve dysfunction).
- Confirmation may be challenging because there is no specific test for valve hemolysis.
- Demonstration of paravalvular leak using either one of the following:
- Transthoracic echocardiography (TTE) – often identifies the site and mechanism of prosthesis dysfunction
- Transesophageal echocardiography (TEE)
- Usually necessary
- Mandatory if peri-mitral leak is suspected
- Degree of hemolysis is not necessarily proportional to the amount of regurgitation; other factors include:
- Irregularity of the leaking site
- Colliding angle
- Mean cell volume may be increased owing to presence of increased reticulocytes.
- Red cell distribution width (RDW) may be increased owing to presence of increased reticulocytes.
- Plasma free hemoglobin concentration may be increased.
- Urine may show hemoglobinuria and/or hemosidinuria.
Management depends on the nature and location of the leak, the clinical condition of the patient, and the available expertise of the heart team responsible for the patient.
- Mild, compensated, hemolysis can often be managed by observation
- Blood transfusion as needed; risks include:
- Transfusion reactions
- Antibody formation
- Iron overload
- Folic acid – prophylactic oral folic acid supplementation is recommended to avoid substantial folate deficiency.
- Iron supplementation – if necessary (iron is lost in the urine).
- Beta blocker – can reduce shear forces in patients with PVL‐related hemolysis reducing blood pressure and heart rate.
- Pentoxifylline – improves blood viscosity and erythrocyte deformability.
- Has been studied in several small series.
- Shown to be effective in reducing blood transfusion rate, especially if there is concomitant renal dysfunction.
- For patients with severe symptomatic hemolysis despite maximal medical therapy.
- Paravalvular leak repair:
- Transcatheter PVL repair
- Open surgical PVL correction:
- Has been shown to be a more effective method in treating severe hemolysis than percutaneous repair
- Recommended by clinical practice guidelines for operable patients with mechanical prosthetic heart valve and intractable hemolysis or heart failure due to severe prosthetic or paraprosthetic regurgitation