Passive cardiac assistance device

Abstract

Artificial implantable active and passive girdles include a heart assist system with an artificial myocardium employing a number of flexible, non-distensible tubes with the walls along their long axes connected in series to form a cuff and a passive girdle is wrapped around a heart muscle which has dilatation of a ventricle to conform to the size and shape of the heart and to constrain the dilatation during diastole. The passive girdle is formed of a material and structure that does not expand away from the heart but may, over an extended period of time be decreased in size as dilatation decreases.

1 . A method for treatment of a patient, whose heart is characterized by ventricular dilatation comprising the steps of, 
 wrapping a girdle around at least the ventricle of said patient's heart; and    maintaining said girdle in a passive state for an extended period of time, said girdle being formed such that it can adjust in size and shape to conform to the outer shape of said ventricle and to not expand its dimension in a direction away from said natural heart.    
     
     
         2 . A method in accordance with  claim 1  wherein said girdle is formed of a sheet of material prestressed in the plane of said sheet to a value below the elastic limit of said material, said sheet having a tension which limits extension away from said heart, while providing compression forces radially inward toward said heart.  
     
     
         3 . A method in accordance with  claim 1  wherein said girdle is formed of a vertically oriented series of sealed, independent, generally horizontally extended cylindrical segments, said vertical orientation being parallel with an axis of the heart running to its apex, including the further step of, 
 introducing fluid into said cylindrical segments to decrease the inner perimeter of said girdle so that its size conforms generally to the size of said patient's ventricle.  
 
     
     
         4 . A method in accordance with  claim 3  and further including means for increasing the volume of fluid within said sealed volume in a controlled fashion to decrease the dimensions of the inner lining when said ventricle decreases in size over an extended period.  
     
     
         5 . A method in accordance with  claim 1  wherein said girdle is formed of a net of interlocking loops, unattached to one another.  
     
     
         6 . A method in accordance with  claim 5 , wherein and said interlocked loops are further interconnected by strings extending in at least a first dimension and including the further step of pulling on said strings to decrease the dimension of said girdle in position around said patient's heart.  
     
     
         7 . A method in accordance with  claim 3  and further including the step of, 
 placing an inner lining between said cylindrical segments and the outer surface of said patient's heart and, placing a tension measuring sensor at the interface between the outer surface of said patient's heart and the inner lining of said girdle, said sensor providing an output signal indicative of the tension of said lining adjacent to said sensor, and, providing said output signal to means for adjusting the amount of fluid within said cylindrical segments until the tension at said lining is at a predetermined value.  
 
     
     
         8 . Apparatus for providing passive support to a natural heart characterized by ventricular dilatation comprising, 
 a girdle for wrapping around said heart, said girdle being formed of a sheet of material prestressed in the plane of said sheet to a value below the elastic limit of said material, such that said sheet has a tension which limits extension away from said heart, while providing compression forces radially inward toward said heart.    
     
     
         9 . Apparatus for providing passive support to a natural heart characterized by ventricular dilatation comprising, 
 a girdle for wrapping around said heart, said girdle comprising a net of interlocked plastic loops, not attached to one another.    
     
     
         10 . Apparatus for providing support to a heart characterized by dilatation of a ventricle comprising, 
 a girdle formed of a vertically oriented series of sealed, independent, generally horizontally oriented cylindrical segments, said vertical orientation being parallel with an axis of the heart running to its apex,    means for providing a fluid to said segments to control the dimensions of said girdle, and    means for changing the volume of fluid provided to said sealed volume only after an extended period of time.    
     
     
         11 . Apparatus in accordance with  claim 10  and further including a distensible lining formed between said cylindrical segments and said natural heart.  
     
     
         12 . Apparatus in accordance with  claim 10  and further including means for providing as an interface between said inner lining and the outer surface of said heart, a cellular wall constructed of myocardial cells harvested from said heart and mounted on a scaffold to generate said cellular wall.  
     
     
         13 . Apparatus for providing support to a heart characterized by dilatation of a ventricle, comprising 
 a girdle formed with open ends, the wall of said girdle being formed of an interconnected vertically oriented series of closed, horizontally oriented, tubes constructed of a flexible, nondistensable material, forming a fluidically sealed volume, said vertical orientation being aligned with an axis of the heart running to its apex,    means for controllably filling said tubes with a fluid, such that when completely filled, each of said tubes assumes a tubular cylindrical shape with a circular cross section, and when emptied of said fluid, each of said tubes assumes a collapsed shape, and    means for providing a selected amount of filling to said tubes with said fluid, and changing said amount only in response to decrease of said dilatation after an extended period of time.    
     
     
         14 . A method of generating the interface between the interior of an external girdle for a natural heart and the myocardium of said natural heart comprising the step of, 
 providing a scaffold of biologically inert material between the lining of said girdle and the exterior myocardial surface of said heart and generating a wall on said scaffold by application of myocardial cells to said scaffold, said myocardial cells being harvested from said heart.