Impact of valve calcification on systolic and diastolic valvular function--an in vitro model

AIM

Despite continuous development of anticalcification treatment for bioprosthetic valves, calcification remains one major cause of structural failure. The aim of this study is to investigate changes in hemodynamic performance and leaflet kinematics in progressively calcified pericardial and porcine aortic valve prostheses.

METHODS

Five pericardial (Edwards Perimount Magna) and 5 porcine (Medtronic Mosaic Ultra) aortic valve prostheses (Ø23 mm) were exposed to a high concentration Calcium-phosphate fluid in an in vitro pulse duplicator (300 cycles/minute) for 6 weeks. The prostheses were removed weekly and tested in an artificial circulation system (70 beats/min, Cardiac Output 5 l/min). All prostheses underwent X-ray, computed tomography (CT)-Scan and photographic examination for evaluation of progressive calcification. Leaflet kinematics were visualized with a high-speed camera.

RESULTS

Pericardial valves demonstrated faster degeneration with significantly larger radiographic areas of leaflet calcification (16.5+/-4.3% versus 5.6%+/-2.0%) and also significantly higher Ca-uptake (170+/-71 microg/mg versus 103+/-49 microg/mg) after 6 weeks. Despite degeneration systolic function remained superior for pericardial valves (mean effective orifice area [EOA] 1.52+/-0.05 versus 1.28+/-0.11 cm2, P<0.01), but leaflet kinematics showed longer closing times (135+/-11 msec versus 85+/-9 msec after 6 weeks) accompanied by higher regurgitant flow (7.8+/-1.12 mL versus 1.2+/-0.28 mL, P<0.001).

CONCLUSION

In vitro pericardial valves calcified faster and more severe than porcine valves leading to impaired diastolic function with prolongation of closing times and higher closing volume. Systolic function remained almost undisturbed by the calcification process. As a consequence in clinical settings, follow-up examinations for structural valve deterioration in porcine valves should focus on systolic performance, in pericardial valves on diastolic function.

Artificial chordae for mitral valve repair: mid-term clinical and echocardiographic results

BACKGROUND

This paper reports on the mid-term clinical and echocardiographic results of mitral valve repair with chordal replacement.

METHODS

Sixty-nine patients (mean age 61 +/- 14 years) underwent mitral valve repair with chordal replacement. The etiology was degenerative in 53 (77 %), rheumatic in 7 (10 %), ischemic in 6 (9 %) and infective in 3 (4 %). Mean ejection fraction was 58 +/- 14. In 35 patients (51 %), a minimally invasive approach was used. Mean follow-up time was 45 +/- 27 months.

RESULTS

Anterior leaflet chordae were replaced in 58 (84 %) patients. There were 3 operative deaths. Freedom from non-trivial recurrent mitral regurgitation (MR) was 81.3 +/- 8.7 % at 97 months. Follow-up echocardiographic controls showed mild recurrent MR in 5 (8 %) patients and moderate in 2 (3.2 %). These two patients required reoperation due to mitral annulus redilation after suture annuloplasty. Competent neochordae were found at reoperation. Freedom from reoperation at 97 months was 96.6 +/- 2.4 %. Four patients died during follow-up resulting in an actuarial survival of 87 +/- 6.2 %.

CONCLUSION

The replacement of chordae tendineae with ePTFE sutures during mitral valve repair has shown good mid-term results. The implantation of the neochordae can be also performed safely using minimally invasive procedures.

Novel SDHD germ-line mutations in pheochromocytoma patients

BACKGROUND

SDHD germ-line mutations predispose to pheochromocytoma (PCC) and paraganglioma (PGL).

MATERIAL AND METHODS

The incidence and types of SDHD germ-line mutations are determined in 70 patients with apparently sporadic adrenal and extra-adrenal PCC.

RESULTS

SDHD sequence variants were identified in the germ line of five patients. Two of three novel mutations were in exon 1 and one in exon 3. One patient had a codon 1 missense mutation (M1K) and a concurrent 3-bp deletion in intron 1. Three of 10 family members had only the exon 1 mutation, whereas one had only the intron 1 mutation. The other exon 1 mutation resulted from a deletion of nucleotides 28-33 with a 12-bp in-frame insertion (c.28_33 del ins TAGGAGGCCCTA). This mutation generated a premature stop codon after codon 9 and was also present in the brother who had a bilateral PCC. The third patient with a carotid body tumour, with an abdominal and a thoracic PGL had a 12-bp deletion in exon 3 (codons 91-94, c.271_282 del). Her father carried the same mutation and had bilateral carotid body tumours. Two further patients, one with six PGL, carried a previously described H50R polymorphism, whose disease-specific relevance is currently unclear. The three patients with bona fide SDHD mutations were younger than those without germ-line mutations.

CONCLUSION

SDHD germ-line mutations are rare in patients with PCC, but their identification is an important prerequisite for the clinical care and appropriate management of affected individuals and their families.