Despite advances in pharmacologic and interventional therapy, development of functional ischemic mitral regurgitation (MR) after myocardial infarction remains a fundamental cause of morbidity and mortality, especially in western societies. In the United States approximately two million patients suffer from functional ischemic MR, and the annual number of deaths related to this clinical manifestation of ischemic heart disease is increasing. The underlying mechanism for this condition is primarily a dilatation of the left ventricular chamber, which leads to displacement of the papillary muscles. Displacement of these cardiac muscular prominences hamper correct closure of the mitral valve during the ventricular systole and therefore the valve becomes insufficient.
Standard surgical therapy for functional ischemic MR at the time of coronary revascularization (coronary bypass surgery) involves the implantation of a mitral annuloplasty ring, designed to restore coaptation by correcting the posterior annular dilatation common in these patients. Although this can be effective in some patients, results have been variable, and persistent or recurrent MR due to progressive ventricular dilatation and papillary muscle displacement has been reported in at least 20% of the patients.
In order to restore the original left ventricular configuration several attempts to restore left ventricular shape and function have been exhibited in form of “Coapsys” device, Dor procedure and Acorn device. However, these principles of treatment are fairly primitive or crude, and therefore do not match the complex anatomy, physiology and mechanics related to the functionality of the mitral valve. Also known in the art are a number of devices for altering the geometry of the heart, e.g. as disclosed in WO 2005/082278, describing a semi-circular papillary muscle and annulus bands for modifying the alignment of papillary muscles, a mitral valve annulus and/or a tricuspid valve annulus. Also disclosed are methods to effect the alignment and a sizing device that can be used for such alignment.
The set of devices disclosed in WO 2005/082278 allows the surgeon to alter, i.e. restore the geometry of the heart. However, all of the above mentioned procedures—including the one disclosed in WO 2005/082278—require that the heart is stopped during the insertion and adjustment of the devices. In this condition the geometry of the heart is very dissimilar to that of the functioning heart since it collapses upon evacuation of blood from its chambers. The adjustment of the functional constituents of the devices—the tension members—during heart arrest may therefore be inaccurate, and the geometry of the device and the heart cannot be altered once the heart is surgically closed, and cardiac function is resumed after the insertion of the device. Therefore, it is difficult to asses if the desired geometry is restored at this stage—before the heart function is resumed.
Consequently, the lengths of the devices must be very thoroughly assessed prior to the surgery procedure. Since the heart with its valves and subvalvular apparatus is a complex dynamic system, where the individual components move in an interdependent and coordinated manner, such an assessment may be extremely difficult. Alternatively, a certain margin of error must be accepted.
There is thus a need for a system and a method for altering the geometry of a heart that allows the altering or at least an adjustment of the geometry of the heart to take place when the heart is beating.
USPTO Backgrounds
USPTO Backgrounds