Single pass lead and method of use

#The present invention relates generally to implantable electrical leads and more particularly implantable single pass cardiac pacing leads.

#It has long been a goal to provide a single cardiac lead which will reliably sense and pace both the atrium and ventricles of a human heart. The simplest approach to providing such lead is simply to add one or more electrodes to the body of a ventricular pacing lead spaced from the distal end of the lead a distance appropriate to locate the added electrodes in the atrium. Such leads are disclosed in U.S. Pat. No. 3,903,897 issued to Woollons and U.S. Pat. No. 3,825,015 issued to Berkovits. While such leads have been proven to sense reliably in the atrium and are currently used in conjunction with VDD pacemakers, their ability to reliably pace the atria is less than might be desired.

#Over the years, numerous designs have been proposed and tested which attempted to provide for reliable positioning of the atrial electrodes on a single pass lead adjacent the tissue of the atria in order to allow for reliable cardiac pacing. These approaches have included the provision of active fixation electrodes for use in the atrium as disclosed in U.S. Pat. No. 4,402,329 issued to Williams and U.S. Pat. No. 4,497,326 issued to Curry and the provision of expandable or extendable arms as in U.S. Pat. No. 3,865,118 issued to Bures and U.S. Pat. No. 4,386,615 issued to Sowton.

#FIG. 1 is a plan view of a first embodiment of a lead according to the present invention.

#FIG. 2 is a cross-section through the body of a lead illustrated in FIG. 1.

#FIG. 3 is an illustration of the lead of FIGS. 1 and 2 as implanted in a human heart, and coupled to an implantable pulse generator.

#FIG. 1 is a plan view of a lead according to a first embodiment of the present invention. The lead is provided with an elongated lead body 10 which may be fabricated of an insulative biocompatible plastic such as polyurethane or silicone rubber. At the distal end of the lead is a ventricular pacing electrode 12, provided with associated pliant tines 14 for assisting in maintaining the electrode in a desired location in the right ventricle in the human heart. The lead body is provided with three curved sections, A, B, and C. Curved section B is provided with a series of sigmoidal or sinusoidal fixation curves extending laterally when in a relaxed condition for a distance greater than the diameter of the superior vena cava into which the lead is intended to be implanted The fixation curves should be at least 2 cm. in lateral width, preferably 2-4 cm. Along section B of the lead are located two atrial pacing electrodes 16 and 18, electrode 16 being located on the outermost portion of one of the defined fixation curves, so that it will bear against the internal surface of the superior vena cava when deployed. Proximal and distal to curved section B are curved sections A and C, each of which are provided with a series of sigmoidal or sinusoidal stretch curves extending laterally to a lesser extent than the fixation curves associated with section B. As described above, the purpose of the stretch curves along A and C is to allow the stretching of the lead in response to the application of tensile force proximal to or distal to section B, allowing the lead to lengthen slightly rather than displacing electrodes 16 and 18 when deployed. The lead body is sized such that when the fixation curves are displayed as illustrated, the distance between the electrode 12 and the electrode 16 is greater than the typical distance from the right ventricular apex to the superior vena cava of a human heart. This distance between electrodes 12 and 16 is preferably greater than 12 cm and more preferably between 12 and 20 cm.

#Curved sections A, B and C may be defined by means of heat treating one or more of the conductors within the lead body and/or by heat treating or molding the plastic of which the lead body 10 is formed to correspondingly form the desired curvature. Mechanisms appropriate for defining curves along the length of the lead body are disclosed in U.S. Pat. No. 3,729,008 issued to Berkovits, U.S. Pat. No. 4,394,866 issued to Hughes, U.S. Pat. No. 5,628,778 issued to Kruse et al. and U.S. Pat. No. 4,402,330 issued to Lindemans, all incorporated herein by reference in their entireties. In one preferred embodiment, the body of the lead 10 is fabricated of silicone rubber or polyurethane and the illustrated curvature is provided by means of a coiled conductor extending from connector pin 28 to electrode 12, which conductor has been heat treated to display the curvature illustrated.

#The proximal end of the lead carries a connector portion 20 which includes two connector assemblies 22 and 24, each of which may be IS-1 type connector assemblies of the type typically employed in conjunction with implantable cardiac pacemakers and defibrillators. Connector assembly 22 is provided with a connector pin 28 which is coupled to electrode 12 at the distal end of the lead and with a metal ring 26 which in this embodiment is not coupled to any electrodes, but which in alternate embodiments would be coupled to an additional electrode such as a ventricular ring electrode or a defibrillation electrode. Connector assembly 24 is provided with a connector pin 32 coupled to electrode 16 and a connector ring 30 coupled to electrode 18.