Mitral valve prosthesis rotator

A prosthetic heart valve rotator with an eccentric socket attached to a bendable shaft. The heart valve is manipulated by a rotator head which is attached to the socket in any of a plurality of selectable angular positions. The rotator head is held in the socket by a spring which circumscribes the socket, thereby reducing stress in the spring.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
Our invention pertains to apparatus for manipulating mechanical heart valve 
prostheses and in particular, for manipulating heart valve prostheses 
implanted at the site of the mitral valve. 
2. Description of Related Art 
Heart valve prostheses may be classified into two general categories: 
bioprosthetic heart valves and mechanical heart valves. By bioprosthetic 
heart valves we mean heart valves with generally flexible leaflets 
comprised of biological tissue. These include leaflets formed of treated 
human valve tissue (allografts), or of treated porcine or other non-human 
tissue (xenografts). By mechanical heart valves we mean heart valves made 
primarily from non-biologic materials, for example, metals, ceramics or 
polymers. These include ball valves and valves having one, two or more 
rigid leaflets. One popular valve design for a mechanical heart valve 
prosthesis includes an annular valve body in which a pair of opposed 
leaflet occluders are pivotally mounted. The occluders are movable between 
a closed, mated position, blocking blood flow in an upstream direction, 
and minimizing regurgitation, and an open position, allowing blood flow in 
a downstream direction. The annular valve body is surrounded by a sewing 
ring which permits the surgeon to suture the valve in place at the site of 
an excised valve. 
When a valve is placed within the heart, it must be accurately oriented to 
maximize its function. Particularly in mechanical heart valves, the 
orientation of the leaflets is critical since their opening and closing 
pathways may otherwise impinge on the surrounding cardiac walls, the walls 
of arteries within which the valve is placed, or the residual valvular 
structures including the tendeae chordae and papillary muscles. This 
difficulty becomes particularly acute in the placement of a heart valve in 
the position of the mitral valve in the heart. When replacing this valve, 
a surgeon will frequently expose the posterior side of the patient's heart 
and enter the heart through walls of the left atrium and sometimes through 
the right atrium. It is desirable to place the valve accurately within the 
cramped confines of the heart while leaving room for the surgeon to sew 
the valve in place. Moreover, accurate sizing of the prosthetic heart 
valve is very important for the long-term viability of the prosthesis. The 
size of the heart valve can frequently not be determined exactly until the 
site of the valve has been exposed. Thus, it is a frequent occurrence that 
a different sized valve may be selected by a surgeon interoperatively. 
In the past surgeons most often used a left thoracotomy surgical procedure 
to reach the heart which allows a straight line of access to the mitral 
valve. Common practice, however, has shifted away from the thoracotomy 
which involves resecting a rib and provides poor access to the aorta. Many 
surgeons today perform a median sternotomy, bisecting the rib cage by 
sawing the sternum in half. This approach provides clear access to the 
aorta and right atrium, allowing the surgeon to easily place the patient 
on by-pass, work on the aortic valve and either the pulmonary or tricuspid 
heart valve. Unfortunately, this approach does not provide easy access to 
the mitral valve, forcing the surgeon to reach behind the heart or through 
the right atrium into the left atrium. 
SUMMARY OF THE INVENTION 
To aid in the rotation of a heart valve within a sewing ring in the mitral 
position, we have invented a heart valve prosthesis rotator. The rotator 
of our invention has an annealed stainless steel shaft which can be bent 
by the surgeon interoperatively, but which will retain its shape 
sufficiently to allow the manipulation of a heart valve engaged by the 
rotator. The rotator has an eccentric socket attached to the stem which 
displaces the structure engaging the heart valve prosthesis from an axis 
of the stem. This allows additional clearance when the heart valve is in 
position so that the surgeon can approach the valve from any orientation, 
even in cases of extremely small atriums, with minimum damage to the 
atrial wall. A rotator head engages the prosthetic heart valve and is 
attached to the eccentric socket. The socket and head snap together with a 
hexagonal bore and hexagonal post respectively. Because of the hexagonal 
configuration of the post and bore, the rotator head can be oriented 
quickly and replicably attached with respect to the eccentric socket. 
Moreover, different size heads can be substituted onto the rotator by 
replacing the rotator head which engages the prosthesis on the eccentric 
socket. 
With the foregoing in mind, it is principal object of our invention to 
provide a heart valve prosthesis rotator with a deformable shaft. 
It is further object of our invention to provide a rotator with an 
eccentric socket and head which engage the prosthesis. 
It also an object of our invention to provide a rotator with replaceable 
rotator heads for different size rotator head and prosthesis combinations. 
Another object of our invention is to provide a socket and rotator head 
wherein rotator heads may be substituted on the socket at a desired 
angular orientation between the eccentric socket and rotator head. 
These and other objects and features of our invention will be apparent to 
those skilled in the art from the following detailed description, taken 
with reference to the accompanying drawings.

DETAILED DESCRIPTION OF OUR PREFERRED EMBODIMENT 
Referring now to the drawings, a heart valve prosthesis rotator, generally 
designated 10, is shown in perspective view in FIG. 1. The rotator 10 
comprises an annealed stainless steel shaft 12 with a plastic handle 14 at 
a distal end thereof. "Proximal" denotes a part of an apparatus which is 
relatively close to the heart when in use, as is customary in 
cardiovascular surgery. "Distal" denotes a part remote from the heart and, 
consequently near the physician. At a proximal end of the shaft 12 is a 
valve engaging means 15 comprising an eccentric socket 16 supporting a 
rotator head 18. 
Mechanical heart valves generally comprise an annular body containing one, 
two or more leaflets or occluders. Leaflets move from a closed position 
impeding the flow of blood to an open position permitting flow of blood. 
In our preferred embodiment, a rotator head for a bileaflet mechanical 
heart valve is described. Those skilled in the art, however, will 
recognize that rotator heads may be constructed for single leaflet valves 
as well as for trileaflet or a multiple leaflet valves without departing 
from the spirit or teachings of our invention. 
The rotator head is seen in through section in FIG. 5. It comprises a 
hexagonal post 20 which attaches to the eccentric socket as more fully 
described below. A lip 22 separates the post 20 from a crown 24. The crown 
24 carries the valve prosthesis. The crown is generally cylindrical in 
shape with a chamfer or curve 26 near a proximal end 28. The proximal end 
28 is formed by two obliquely intersecting planes 30, 32. The planes 30, 
32 support the inflow faces of two leaflets of a bileaflet heart valve 
(not shown) and hold the leaflets in closed position while the valve is 
being rotated within the heart. In the mitral position, the inflow faces 
of the heart valve will be adjacent the left atrium, while the outflow 
faces will be implanted adjacent the left ventricle. In our preferred 
embodiment, the rotator head is formed of thermo setting plastic to 
minimize the possibility of damage to the leaflets of the prosthesis. For 
ease of molding, a cavity 34 is provided within the rotator head. The 
cavity is shaped so that the walls of the rotator head are of relatively 
uniform thickness. This minimizes stresses and deformation during molding. 
A groove 36 encircles the post 20 for snapping the rotator head into the 
eccentric socket, as will be more fully described below. 
The eccentric socket 16 is also molded of plastic and is attached to a 
proximal end of the annealed shaft 12. The socket 16 comprises a body 38 
connected to the shaft with a lateral ledge 40 extending generally 
perpendicularly with respect to the shaft. An hexagonal through bore 42 
extends through the ledge 40 and receives the hexagonal post 20. When the 
head 18 and socket 16 are assembled, the post 20 protrudes above the ledge 
40, as shown in FIG. 2. Pressing on the post disengages the head 18 from 
the socket 16. A lateral slot 44 is formed in the ledge and extends around 
the ledge 40, forming an exposed lip 46 on the body 38 opposite the ledge 
40. A "D" shaped, split retaining ring or spring 48 inserted both into the 
slot 44 and on the exposed lip 46 captures the hexagonal post of the 
rotator head by engaging the groove 36 mentioned above. The slot and lip 
generally define a "D" shaped seat for the retaining ring 44, when viewed 
from the top as, for example, in FIG. 7. The center of this seat is so 
orientated that the segment of the "D" ring intersects the hexagonal 
through bore 42, as can be seen in FIG. 4. This permits the retaining ring 
48 to be exposed within the hexagonal through bore as seen in FIG. 7. When 
the rotator head is inserted into the eccentric socket, the retaining 
spring 48 will engage the groove 36, holding the head and socket together. 
Advantageously, this configuration produces a spring which deforms 
radially, so deflection is small with respect to the size of the spring 
and fatigue resistance is increased. 
The valve engaging means 15 comprising, in combination, the eccentric 
socket 16 and the rotator head 18, has an overall proximal-to-distal 
length (dimension L in FIG. 2) of 3 cm or less. This is particularly 
important where a patient's heart is small, especially in children. 
The preferred embodiment of our invention provides several advantages as a 
result of the features described above. Because the rotator head is 
detachable from the eccentric socket, multiple different valve sizes can 
be engaged with the same handle, stem and socket combination. The surgeon 
is able to bend the stem to obtain the best orientation for engagement of 
a valve. If the surgeon notes that a different size heart valve is 
required, the rotator head can be easily removed and a new rotator head 
for engaging a different size valve can be snapped into the eccentric 
socket. Because of the anti-rotation feature of the hexagonal post and 
hexagonal bore, the new rotator head can be placed in the correct 
orientation to engage the previously implanted valve. The stem will not 
need to be reshaped, but the valve can be rotated in position. 
Even in a large heart, cardiac surgery by median sternotomy makes the 
availability of a bendable handle important. In cases where the heart is 
small, such as with children, the reduced length of the component that 
contacts the valve becomes very important because the atrium can be as 
small as a few centimeters in length. 
Moreover, after the initial placement of the valve, the rotator head and 
can be incrementally rotated to engage the valve and to obtain the best 
overall orientation of the leaflets. This orientation can then be refined 
by bending the stem. 
The foregoing description of a preferred embodiment of our invention is 
intended in all respects to be illustrative, and not restrictive, and it 
is intended that our invention be defined by the scope of the appended 
claims. Any variations which fall within the meaning and scope of 
equivalence of the claims are intended to be included herein.