Surgery: light – thermal – and electrical application – Light – thermal – and electrical application – Electrical energy applicator
Reexamination Certificate
1998-12-03
2001-08-21
Layno, Carl H. (Department: 3737)
Surgery: light, thermal, and electrical application
Light, thermal, and electrical application
Electrical energy applicator
C607S123000
Reexamination Certificate
active
06278897
ABSTRACT:
FIELD OF THE INVENTION
This invention lies in the area of medical electrical stimulation, and, more particularly, a medical electrical lead and introducer system.
BACKGROUND OF THE INVENTION
In many cardiac pacing, defibrillation and cardioversion applications, it has been found useful to employ an atrial “tine” on the lead, to improve positioning and fixation of the lead electrode against or in close proximity to the atrial wall. For a DDD type pacing lead, for example, where a single lead is used to pace and sense in the ventricle and the atrium, there is no distal end of the lead within the atrium which can be simply guided into a position where it can efficiently pace and sense. Rather, it is necessary to include some design feature to ensure that the lead portion carrying the atrial electrode or electrodes is held close enough to the atrial wall to provide reliable operation. It has been found that incorporation of an atrial tine, which in this context is a relatively small arm, or extension from the main lead body, can provide a marked improvement in terms of holding the atrial electrode or electrodes in good position. Examples of leads which use such atrial tines are shown in the patent art, e.g., U.S. application, Kruse et al., Ser. No. 08/794,402, filed Feb. 3, 1997. It is to be understood that the atrial tine carries one or more electrodes at its distal end, and a coil conductor or conductors for electrically connecting to such electrode(s).
Conventionally, the lead is inserted into the heart through an introducer, which is a hollow tube having in inner lumen of greater diameter than the lead body diameter. The introducer is first inserted into a vein and then down into the heart, in a well known manner. Following this, the lead is guided through the introducer into the heart, and positioned for optimum pacing and sensing. Generally, re-positioning is required, as often the first attempt does not produce the best possible position for stimulation threshold. The re-positioning involves withdrawing the lead back through the introducer, and then reinserting it, e.g., so that the far distal end is positioned in the right ventricular apex. A problem arises in such re-positioning, where the lead carries an atrial tine. When the lead is withdrawn, the atrial tine is often caused to kink within the introducer. Extending the tine longitudinally is not a problem, but transverse kinking often occurs, which produces high stresses in the electrode coil (conductor). Such kinking can be caused several times, depending on how many times the physician needs to re-position the lead. Tests have shown that this can lead to coil breakage, which would destroy the atrial function of the lead. Coil breakage in a lead is, of course, disastrous for the patient, and any condition which could accelerate such a result must be avoided.
Another problem that bothers many physicians during lead introduction is that of blood leakage through the introducer. The introducer inner diameter is necessarily larger than the lead body diameter, in order to permit easy passage through the introducer, and to accommodate, e.g., fixation type tines as may be positioned at the distal end of the lead, and which extend laterally from the lead body. For example, for a 14 French introducer and an 8 French body diameter lead, a lot of blood leakage occurs between the lead body and the introducer while the physician maneuvers the lead through the introducer and into position.
It is to be noted that generally it is not a solution to withdraw the introducer before repositioning the lead. If this is done, it is necessary to squeeze the vein around the lead body in order to reduce blood leakage. Such a procedure becomes even more difficult, if not impossible for one physician, when a stylet has to be inserted for the repositioning. In any event, if the repositioning takes a long time, there is such significant blood leakage that this is unacceptable to most physicians. Further, if the introducer is not in place during repositioning, the atrial tine may enter a vein junction or other unintended area, and thus the introducer is kept in place to protect against such a possibility.
In view of the above, it is seen that there exist several problems with the current method and apparatus for introducing leads into a patient's heart for cardiac treatment. It is desirable to provide an improvement to reliably safeguard against atrial tine transverse kinking, and also to reduce the blood leakage through the introducer at time of lead implantation. It is an object of this invention to provide a simple but effective way to both prevent transverse tine kinking and to substantially eliminate the undesirable blood leakage through the introducer.
SUMMARY OF THE INVENTION
A medical electrical lead and introducer system. The lead is a single pass, dual chamber lead, which features in one embodiment an atrial tine. The introducer system is particularly designed for introduction of single pass, dual chamber lead which has an atrial tine. The introducer system facilitates the introduction of a such lead into a patient's heart while safeguarding the tine from damage due to kinking during lead positioning. The lead generally features several lengths each having differing stiffness as well as a pre-formed bend. The lead also features a atrial tine having an electrode at the tip. Due to the relatively fragile as well as difficult to maneuver lead, an introducer system is also disclosed. The introducer system feature a removable tubing split element surrounds the atrial tine area of the lead while it is disposed through the introducer sheath, the split element both blocks the tine from lateral movement and fills up the space between the lead body and the introducer, thereby preventing blood leakage through the introducer. The element also has a longitudinal split for receiving the atrial tine while holding it against transverse movement when the lead is being repositioned. After optimal positioning of the lead, the tubing split element is withdrawn, and then the introducer is withdrawn. The tubing split element is a generally cylindrical piece of TEFLON, here called a tube split element, or just a “tube split”, is positioned around the lead body in the atrial tine area. The tube split element has a thickness which substantially fills the radial gap between the smaller diameter lead body and the introducer inner cylindrical wall, and has a longitudinal separation, or split, which accommodates the atrial tine, thereby permitting the tine to extend longitudinally but not transversely. The tubing split element is preferably mounted on the lead at the time of lead assembly. It has a length sufficient to extend proximally out of the introducer so that it can be withdrawn, and has a longitudinal tear line whereby the element can be separated and removed from the lead after final positioning of the lead.
In practice, the physician first inserts the introducer so that it extends into the patient's heart. Then, the lead, with the tubing split element in place around it, is passed through the introducer and into the heart. For a DDD type lead, the distal end is positioned in the right ventricular apex. It is then withdrawn and re-positioned as many times as necessary, to find the best location for optimum threshold. During these re-portioning steps, the tubing element prevents transverse kinking of the atrial tine, or tines, and minimizes blood leakage through the introducer. After this, the physician first withdraws the tubing split element proximally to clear the end of the introducer, separates it and removes it from the lead. Then the introducer is withdrawn and likewise removed from the lead. After this, of course, the proximal end of the lead is attached to the stimulus device, e.g., pacemaker, defibrillator, etc.
REFERENCES:
patent: 4057067 (1977-11-01), Lajos
patent: 4553961 (1985-11-01), Pohndorf et al.
patent: 4585013 (1986-04-01), Harris
patent: 5129405 (1992-07-01), Milijasevic et al.
patent: 5312360 (1994-05-01), Behl
patent: 544
Lokhoff Nicolaas
Rutten Jean J. G.
Smits Karel
van Venrooij Paulus
Jaro Michael J.
Layno Carl H.
Medtronic Inc
Pattom Harold
Woods Thomas F.
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