Animal models of mitral regurgitation induced by mitral valve chordae tendineae rupture.

BACKGROUND AND AIM OF THE STUDY: Mitral regurgitation (MR) is a common valvular disease throughout the world. Various diagnostic techniques have been developed to assess the causes and severity of MR, and the therapeutic approaches to this disease have been widely documented. However, treatments for chronic MR remain controversial, and various animal models of chronic MR (including chordae tendineae rupture, rapid pacing and ischemia) have been developed to study the pathophysiology and therapeutic approaches to this condition. The study aim was to review the animal MR models that have been developed using a mitral valve chordae tendineae rupture technique. METHODS AND RESULTS: Among the animals used for these investigations, dogs and sheep have been most commonly used as models of MR induced by mitral valve chordae tendineae rupture, mainly due to considerations of cardiac size. Chordae tendineae cutting is performed using either closed- or open-chest techniques. In the closed-chest model, long flexible grasping forceps are positioned percutaneously in order to tear the mitral valve chordae. In the open-chest model, cardiopulmonary bypass is performed, and either selected chordae are cut under direct visualization or a non-specified number of chordae are cut, using a metal device inserted through the left ventricular apex. Whichever model is used, MR has been found to become chronic at three to six months after the induction of MR by chordae rupture. The reported mortality and complication rates of these models are high. CONCLUSION: In the long term, the experimental evolution of chronic MR is similar to the evolution occurring naturally in patients suffering from the condition. Hence, these models could be useful in understanding the disease better, and in testing new therapeutic modalities. The present review summarizes the physiological effects of each of these techniques, and compares the advantages and disadvantages of each procedure.

Repeatability, variability and reference values of pulsed wave Doppler echocardiographic measurements in healthy Saanen goats.

BACKGROUND: Pulsed wave (PW) Doppler echocardiography has become a routine non invasive cardiac diagnostic tool in most species. However, evaluation of intracardiac blood flow requires reference values, which are poorly documented in goats. The aim of this study was to test the repeatability, the variability, and to establish the reference values of PW measurements in healthy adult Saanen goats. Using a standardised PW Doppler echocardiographic protocol, 10 healthy adult unsedated female Saanen goats were investigated three times at one day intervals by the same observer. Mitral, tricuspid, aortic and pulmonary flows were measured from a right parasternal view, and mitral and aortic flows were also measured from a left parasternal view. The difference between left and right side measurements and the intra-observer inter-day repeatability were tested and then the reference values of PW Doppler echocardiographic parameters in healthy adult female Saanen goats were established. RESULTS: As documented in other species, all caprine PW Doppler parameters demonstrated a poor inter-day repeatability and a moderate variability. Tricuspid and pulmonary flows were best evaluated on the right side whereas mitral and aortic flows were best obtained on the left side, and reference values are reported for healthy adult Saanen goats. CONCLUSIONS: PW Doppler echocardiography allows the measurement of intracardiac blood flow indices in goats. The reference values establishment will help interpreting these indices of cardiac function in clinical cardiac cases and developing animal models for human cardiology research.

Impact of global left ventricular afterload on left ventricular function in asymptomatic severe aortic stenosis: a two-dimensional speckle-tracking study.

AIMS: The present study sought to assess the effect of global left ventricular (LV) afterload on LV myocardial systolic function in patients with aortic stenosis (AS) and preserved LV ejection fraction. METHODS AND RESULTS: We prospectively examined the LV myocardial deformation (i.e. longitudinal, radial, and circumferential) by two-dimensional speckle tracking in 173 patients with asymptomatic severe AS. Thirty-eight patients (22%) had low flow as determined by a low stroke volume index (or=5 mmHg mL/m(2)). Systemic arterial compliance (P = 0.001), circumferential myocardial deformation (P = 0.024), and left atrial area index (P = 0.04) were independently associated with increased global LV load in multivariable analysis. Of note, LV ejection fraction was not identified as a determinant of low flow or increased afterload. CONCLUSION: In asymptomatic patients with severe AS, LV ejection fraction markedly underestimates the extent of myocardial systolic impairment. Intrinsic myocardial dysfunction is particularly common in patients with increased global LV afterload, and especially in the subset of patients with low-flow AS.

[New trends in treatment of hypertrophic cardiomyopathy]. / Actualités thérapeutiques dans la cardiomyopathie hypertrophique.

The management of patients with hypertrophic cardiomyopathy has largely evolved over the past two decades. One important finding is that medical treatment appears under used. Invasive procedure are reserved to patients with obstructive hypertrophic cardiomyopathy who remain symptomatic despite optimal medical treatment. Indications for implantable cardiac defibrillator are still debated. A global and multidisciplinary approach of the patient and of his family is mandatory.

The blue man: an unusual happy end of a spontaneous rupture of a coronary artery.

We report the case of spontaneous rupture of a coronary artery. It was that of a 56-year-old man admitted for dyspnoea and anterior thoracic pain. The most striking feature on physical examination was the marked cyanosis of his face, upper part of the thorax and the upper limb. The patient was haemodynamically unstable with tachycardia and hypotension. Cardiac tamponade was confirmed by echocardiography and computed tomography of the thorax. The patient was transferred for surgery. Emergency sternotomy revealed pericardial bloody effusion and a continuous bleeding around the posterior interventricular artery. No other perioperative findings could explain the haemopericardium. Haemostasis was obtained by a suture of the bleeding coronary artery.