The fixation tines of the Micra™ leadless pacemaker are atraumatic to the tricuspid valve.

BACKGROUND: Today, there is no manufacturer-supplied retrieval tool for the Micra™ pacemaker (Medtronic, Minneapolis, MN, USA); therefore, off-the-shelf catheters have been employed for retrievals. The proximal retrieval feature of the Micra™ can be snared and the device is then retracted from the myocardium, pulling the device through the tricuspid valve. This study characterizes the potential risks of Micra™ nitinol tine engagement with the tricuspid sub-valvular apparatus. METHODS: Fresh human hearts nonviable for transplant (n = 10) were obtained from our regional organ procurement agency (LifeSource, Minneapolis, MN, USA). Micra™ fixation tines were affixed to a linear force transducer. Tines were then engaged in tricuspid chordae tendineae to conduct a constant velocity tensile test. Each test was run until tines disengaged from the chordae tendineae or until they released from the valve apparatus. Subsequently, biomechanical failure properties of the valve apparatus and isolated chordae tendineae were determined using a series of uniaxial tensile tests. RESULTS: There were no chordal ruptures observed during our Micra™ tine extraction testing. Chordal failure required 15.0 times the force of extracting a single engaged tine, and 9.0 times the force of extracting two engaged tines. The uniaxial stresses required for isolated chordal failure averaged 17.4 N/mm2 ; failure strains exceeded 150% resting chordal length. CONCLUSIONS: The forces required to rupture tricuspid chordae tendineae significantly exceeded the forces potentially imposed on the chordae during Micra™ device retrievals. We conclude that the fixation tines of the Micra™ device are unlikely to damage the tricuspid apparatus during either implant or retrieval.

Acute mitral regurgitation due to ruptured ePTFE neo-chordae.

Chordal replacement with expanded polytetrafluoroethylene (ePTFE) sutures has proven to be a simple, versatile, and durable technique for the treatment of prolapsed cusps causing mitral valve regurgitation. ePTFE is known for its strong resistance to tension, and is judged to be unbreakable under physiological conditions. Herein are reported two cases of rupture of synthetic chordae tendineae; the possible causes of this extremely rare finding are analyzed.

Correction of traumatic tricuspid insufficiency using the double orifice technique.

Traumatic tricuspid insufficiency is an uncommon clinical condition and surgical procedures vary. In this paper we report our experience in treating traumatic tricuspid insufficiency using the double orifice technique. From January 2000 to September 2003, 10 patients with traumatic tricuspid regurgitation were admitted to our hospital, 5 of whom were corrected using the double orifice technique. There were 4 males and 1 female with ages ranging from 31 to 52 years. Preoperative transthoracic echocardiography (TTE) detected severe tricuspid regurgitation in 4 patients and moderate tricuspid regurgitation in 1 patient. At surgery, tear of the tricuspid anterior papillary muscle was found in 2 cases and anterior chordal rupture in 3 cases. The valves were successfully repaired using the double orifice technique in combination with ring annuloplasty. There was no repeat operation, no operative complications or deaths. Before discharge, TTE detected normal tricuspid valve function in 2 cases and tiny regurgitation in 3 cases. After a follow up of 8 to 36 months, TTE demonstrated normal valve function in 1 patient and tiny regurgitation in 4 patients. The double orifice technique appears to be a simple but effective method of repairing traumatic tricuspid incompetence. Satisfactory clinical outcomes can be produced in carefully selected patients.

Valve repair with chordal replacement for traumatic tricuspid regurgitation.

A 70-year-old woman who had fatiguability due to right heart failure seven years after receiving blunt chest trauma in a road traffic accident presented to our hospital. Preoperative echocardiography revealed severe tricuspid regurgitation resulting from prolapse of the anterior leaflet. The valve was repaired by chordal replacement with expanded polytetrafluoroethylene sutures and DeVega annuloplasty. At three months after surgery, the patient is in good clinical condition, and repeat echocardiography revealed only mild tricuspid regurgitation.

Mitral valve repair for severe mitral regurgitation caused by endomyocardial biopsy.

Mitral regurgitation (MR) following endomyocardial biopsy is a rare and severe complication. A 70-year-old man with severe MR due to chordal injury caused by left ventricular endomyocardial biopsy is described. In this patient, a few chordae tendineae of the posterior-median papillary muscle were injured by the biopsy forceps. Due to the chordal rupture, both anterior and posterior leaflets were prolapsed and severe MR developed. MR was successfully treated by artificial chordal replacement using extended polytetrafluoroethylene sutures and ring annuloplasty. This mitral valve repair with artificial chordal replacement was considered suitable to treat MR resulting from iatrogenic chordal injury as the leaflets were not involved in the degenerative process and papillary muscle function was preserved. To avoid MR, the transvenous approach should be used routinely for endomyocardial biopsies; biopsy from the left ventricle is not justified.

[A case report of mitral valve repair of broad posterior leaflet prolapse due to ruptured chordae tendinea by replacement of chordae tendineae with EPTFE sutured and Carpentier-Edwards ring techniques].

A 68-year-old woman with mitral valve regurgitation due to ruptured chordae tendineae of posterior leaflet underwent mitral valve repair by replacement of chordae tendineae with EPTFE sutures and Carpentier-Edwards ring techniques. Preoperative study showed massive mitral regurgitation and moderate tricuspid regurgitation with CTR 54% of chest X-ray. The postoperative course was not eventful. Postoperative study showed trivial mitral and trivial tricuspid regurgitation. Postoperative CTR was 45%. Mitral valve repair by these techniques could be modified and applicable to mitral valve regurgitation due to ruptured chordae tendineae of posterior leaflet. There was no complication during follow-up period of 8 months.