Electrical connectors – With coupling movement-actuating means or retaining means in... – Retaining means
Reexamination Certificate
2001-06-22
2002-05-21
Bradley, P. Austin (Department: 2833)
Electrical connectors
With coupling movement-actuating means or retaining means in...
Retaining means
C439S904000, C439S349000, C607S037000
Reexamination Certificate
active
06390843
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to an electrical connector system for use with an implantable medical device such as a pacemaker for connecting an implantable electrical lead to the electrical circuits contained within a hermetically sealed housing of the medical device.
BACKGROUND OF THE INVENTION
While the present invention will be described in a specific manner as being applicable to a pacemaker, it will be understood that the invention is applicable to any other type of implantable medical device intended to stimulate body tissue.
Modem pacemakers monitor the activity of a heart and provide a stimulation pulse in the absence of normal heart activity. Advantageously, such devices are relatively small, light-weight and implantable. In order to sense and stimulate the heart, however, such pacemakers must be used with a pacemaker lead, an electrical conductor that carries electrical signals between the heart and the pacemaker. Advantageously, the pacemaker lead can be inserted into the heart transvenously through a relatively simple and well-known surgical procedure. Disadvantageously, one end of the lead (designated herein as the “connecting end”) must be electrically and mechanically secured to the pacemaker in a way that provides for a long-term safe and secure, yet detachable connection. Those skilled in the pacemaker art have long sought for a simple, yet reliable and safe, technique for making this detachable electrical and mechanical connection between the pacemaker device and the connecting end of the pacemaker lead.
In order to appreciate the advantages of the present invention, it will help first to have a basic understanding of the manner in which the mechanical and electrical connection functions are carried out in known pacemakers. The main components associated with the connection function of such known pacemakers are shown diagrammatically in
FIG. 1. A
pacemaker
10
electrically includes a battery
14
that powers electrical circuits
12
. The pacemaker electrical circuits
12
and battery
14
are mechanically enclosed and hermetically sealed in a suitable housing
16
. Typically, this housing or case
16
is shaped to include a flat side or platform
20
to which a suitable epoxy connector
22
can be bonded. At least one feedthrough terminal,
18
, in electrical contact with the electrical circuits
12
, passes through the case or housing
16
and protrudes beyond the platform
20
. This feedthrough terminal
18
is electrically isolated from the case
16
. A platinum wire
24
, or other suitable conductive element, connects the terminal
18
to a conductive connector block
26
that is fitted within the connector
22
. A pacemaker lead
28
, having a proximal electrode
30
, connects to the pacemaker electrical circuits by inserting the proximal electrode
30
into a receiving channel
31
of the connector
22
until the electrode
30
is in contact with the connector block
26
. A set screw
32
is then securely tightened using a torque wrench
34
to firmly hold the electrode
30
in both mechanical and electrical connection with the connector block
26
. A septum, not shown but having the construction generally described in commonly assigned U.S. Pat. No. 5,509,928 issued Apr. 23, 1996 to Acken, is typically placed over the set screw
32
in order to prevent body fluids from seeping through the set screw hole. Further, sealing ribs or ridges
36
on the connecting end of the pacemaker lead are designed to tightly engage the inside edges of the receiving channel
31
in order to prevent any body fluids from entering into the receiving channel
31
once the connecting end of the lead has been inserted into the connector
22
.
While the descriptions presented in the prior art vary greatly relative to, for example, different types of locking mechanisms for performing the mechanical connection function, or different types of arrangements for performing the electrical feedthrough function, including the use of bipolar or multiple pacemaker leads, all such systems include the use of a premolded or cast connector
22
that is bonded to a sealed pacemaker housing
16
in which the electrical circuits are located.
Typically, prior art connectors
22
are cast in place from epoxy to the platform or header
20
of the pacemaker, or a premolded connector is bonded to the platform
20
using a suitable sealing and bonding agent. Further, once the electrical connection is made from the terminal post
18
to the connector block
26
, and the connector is attached to the housing, all remaining voids within the connector
22
, not including the receiving channel
31
into which the proximal end of the pacemaker lead
28
is to be inserted, must be filled with a suitable filler material, such as a two-component epoxy or silicone rubber.
As is evident from the above description, placing a connector on a pacemaker housing is a very labor-intensive process involving many components. What is needed is a similar manner of lead attachment that provides the requisite mechanical and electrical connection functions using fewer components and less labor yet providing higher reliability. The present invention addresses these and other needs.
In a subsequent development, as disclosed in U.S. Pat. No. 5,951,595 issued Sep. 14, 1999 to Moberg et al., an active lock but passive release connector assembly includes an entrance block leading to lead receiving channels of an implantable medical device provided with two seals which, when compressed by the entrance block, lock onto the body of each lead. As one drawback of the Moberg et al. device, it periodically occurs that when the leads need to be extracted and the mechanism is released, causing the plunger to move back away from the seals, it sometimes occurs that the seals remain tightly locked onto the leads after the plunger is released from the seals. This requires a higher extraction force than should normally be necessary. In the present invention, in contrast, when the mechanism is loosened, the clamp is actively released from the lead body, enabling the lead to then be easily extracted from the device.
It was with knowledge of the foregoing state of the technology that the present invention has been conceived and is now reduced to practice.
SUMMARY OF THE INVENTION
A connector system for use with a sealed implantable medical device includes an entrance block attached to the medical device with an inlet bore for receiving an electrical lead such that, when attached to the medical device, the inlet bore is coaxial with the lead receiving channel of the medical device. A clamp assembly within the entrance block includes a mounting member, a cylindrically shaped loop clamp unitary with the mounting member having an adjustable diameter, the loop clamp being coaxial with the inlet bore and movable between a first position disengaged from the electrical lead and freely permitting withdrawal of the electrical lead from the inlet bore and a second position firmly engaged with the electrical lead received in the inlet bore so as to prevent its withdrawal from the inlet bore, and an actuator mechanism for shifting the loop clamp between the first and second positions.
In a preferred design the connector system is intended for use with an implantable medical device having a pair of lead receiving channels while incorporating all of the features of the single lead receiving channel design.
It is a feature of the present invention to provide an electrical connector system for use with an implantable medical device such as a pacemaker for connecting an implantable electrical lead to the electrical circuits contained within a hermetically sealed housing of the medical device.
It is a further feature of the present invention to provide such an electrical connector system which enables the electrical leads to be readily selectively firmly attached to the medical device in one instance and just as readily detached in another instance.
Still a further feature of the present invention is to provide such an electrical
Bradley P. Austin
Gushi Ross
Pacesetter Inc.
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