Hemolysis occurs in the majority of patients with mechanical prosthetic valvular replacement. On the contrary, hemolysis following MVR and annular ring placement is uncommon because there are no moving mechanical parts or prosthetic leaflets.6 Mechanisms of hemolysis following MVR that have been suggested include the ‘whiplash motion’ of the residual free-floating chordae tendineae, collision of the regurgitant jet into the prosthetic ring, central jets colliding with the atrial wall, fragmentation of the regurgitant jet by a dehisced annuloplasty ring, nonendothelialization of annuloplasty ring, and rapid acceleration of a jet through a small para-ring channel.2, 3, 7–9 This case is a unique case. The major cause of the mechanical hemolysis was mild mitral regurgitation which originated from the centre of the valve and striking the annuloplasty ring. And we suspect that non-endothelialization of artificial chordae tendinae may another cause.
Although intravascular hemolysis is common after placement of a prosthetic valve or valve repair, there have been only few reported cases of severe acute RF in the literature.4, 6 This case was an uncommon case. It developed shortly to severe acute RF. Plasmapheresis and blood transfusion were not effective. Pharmacological approaches with the use of antioxidants or agents directed at increasing red blood cell flexibility or decreasing hydrodynamic shear forces were also invalid. Hemodialysis was required finally. Hence, acute RF from hemolysis after MVR is a rare, but serious, complication that should be recognized because chronic kidney disease may ensue.6
Expanded polytetrafluoroethylene is a linear, nonabsorbent monofilament polymer that has been used in cardiovascular surgery patches and sutures for many years and has many documented advantages over other suture materials.10, 11 MVR surgery with implantation of expanded polytetrafluoroethylene chordae tendinae has been offered as a safe and effective surgical alternative for mitral valve. However, it has been reported that expanded polytetrafluoroethylene suture was calcified and ruptured and that no connective tissue or calcium deposits was found in the suture material.10–12 We report a unique case of completely non-endothelialized expanded polytetrafluoroethylene. We suspect that non-endothelialization of the expanded polytetrafluoroethylene might play a role in the genesis of mechanical hemolysis. But it is difficult to identify whether it is primary or secondary.
Residual mitral regurgitation was the major cause to mechanical hemolysis. High velocity mitral regurgitant jet could denude the endothelium, expose the expanded polytetrafluoroethylene surface, prevent complete endothelialization of expanded polytetrafluoroethylene and increase the risk of hemolysis.2 In the case presented here, the velocity of the regurgitant jet as assessed by Doppler analysis was 2.3 m/s. Such a high-speed jet could cause turbulence and increased trauma. Although many reported cases had high grade mitral regurgitation, echocardiography only showed mild mitral regurgitation and no other structural findings in this case.1 Therefore, though rarely, the clinician should have an index of suspicion for mechanical hemolysis even if the mitral regurgitation is mild or trivial.