A Rare Case of Left Ventricular Outflow Tract Obstruction 18 Years after a Mechanical Mitral Valve Replacement

Background: Left ventricular outflow tract (LVOT) obstruction is a serious complication that can occur after various mitral-valves, surgical or percutaneous, interventions. It was rarely described in mechanical mitral valve replacements. Aim: to describe a rare case of late LVOT obstruction after a mitral valve replacement by a low-profile mechanical prosthesis. Case Presentation: A 48-year woman, with a history of rheumatic mitral valve disease and mechanical mitral replacement by a hemi-disc valve 18 years ago, presented for a recent dyspnea. Echocardiography showed a narrowing of the LVOT, with anterior position of the mitral prosthesis, aorto-mitral annular angulation, septal thickening and remnant native sub-valvular tissue attached to the septum in the LVOT region. This resulted in LVOT obstruction with a peak gradient of 75 mmHg. The heart team opted for a redo surgery, but the surgical decision was refused by the patient. Discussion: This is a rare case of late LVOT obstruction after mitral valve replacement by mechanical low-profile prosthesis. Preserved native mitral valve tissue, which is the main described cause of LVOT obstruction after mechanical mitral valve replacements was not the unique cause of obstruction in this patient who had also a septal thickening and anterior prosthetic position. Aorto-mitral annular angulation that was identified as a risk factor of LVOT obstruction after trans-catheter mitral valve replacements, should be, probably, also took into account and assessed pre-operatively in patients undergoing surgical mitral replacements. Conclusion: LVOT obstruction can occur after mechanical mitral replacements event with low profile prosthesis. In patients with identified risk factors of LVOT obstruction, preservation mitral anterior leaflet should be avoided, and preservation of other native mitral tissue should be discussed.

[Contrast-induced nephropathy after cardiac catheterization: a prospective study of 180 patients]

Contrast-induced nephropathy [CIN] is associated with an increased cardiovascular morbi-mortality. Little is known about the incidence and risk factors of CIN after cardiac catheterization in Tunisian patients. To determine the incidence of CIN and its predictors after coronary angiography as well as its prognostic and therapeutic repercussions in a Tunisian patients' cohort. In this prospective single center study, 180 consecutive patients who underwent cardiac catheterization were enrolled; all patients were followed-up for 3 months. The incidence of CIN defined as an absolute increase in serum creatinine >/= 5 mg/l [44micromol/l] and/or a relative increase in serum creatinine >/= 25%, was 17.2%. In multivariate logistic regression, independent predictors of CIN were: diabetes mellitus [Odds Ratio [OR]=2.26 ; 95% confidence interval [95%CI]: 1.29-3.98, p=0.005], creatinine clearance < 80ml/mn [OR=2.87 ; 95%CI: 1.59-5.19, p<0.001], left ventricular ejection fraction [LVEF] < 45% [OR=2.03 ; 95%CI: 1.22-3.39, p=0.007] and use of a volume of contrast media > 90ml [1.72 ; 95%CI: 0.99-2.99, p=0.05]. Perprocedural hypotension was the strongest independent predictor of CIN in our study [OR=3.99; 95% CI: 1.65-9.66, p=0.002]. CIN was totally regressive within one month in 27 patients [86.7%] while 3 patients [10%] had a residual renal dysfunction at the end of the follow-up period [3 months]. More than one angiocoronarography on 6 resulted in CIN in our population. CIN affects cardiovascular prognosis even if renal function normalization is usually obtained within one month after the investigation. Besides identifying risk factors of CIN in order to apply preventive measures in risky patients, we stress the necessity of insuring a good hemodynamic status while achieving the procedure

[Stress echocardiography and mitral stenosis: what interest?]

The stress echocardiography is used extensively as a diagnostic and prognostic tool and the assessment of ischemic cardiopathies. Its use in valvulopathies is more limited, but is increasing with time. The discrepancies between the functional symptoms and hemodynamics at rest is frequently met in patients with mitral stenosis. By assessing changes of pressures, gradients and surface stress echocardiography helps to identify the real hemodynamic conditions permitting to recommend a more aggressive approach in certain situations

[Introduction of the myocardal dopler tissue imaging]

Introduced in 1989, the myocardial doppler tissue imaging has now many clinical applications. The doppler tissue imaging explores the proper systolic and diastolic regional function of myocardial fibers. We can measure myocardial velocities by recording signals of low v‚locitiy and high magnitude, the strain and the strain rate are then derived from velocities. Specific softwares are therefore necessary. There are many ways of recording and representing myocardial doppler tissue parameters. Diagnostic and prognostic value of myocardial doppler tissue imaging is now proved and this method has many applications in ischemic cardiopathy and in cardiomyopathies. The development of powerful softwares is promising for the applications of the strain in the future