Abstract: A conformable catheter comprising a catheter handle, an elongated catheter tube, and a distal tip portion of the catheter tube, capable of assuming a desired pre-programmed shape. A wire member is disposed within the core of the catheter's tip portion and is formed of a material, such as, for example, a shape-memory binary nickel-titanium alloy, that will assume a pre-programmed shape after pre-shaping, heat treatment, cooling and subsequent heating. To pre-program the shape of the wire member, prior to assembly of the catheter, the wire member is wound around a shaped, heat resistant fixture, heated until the temperature of the wire member exceeds the temperature at which the shape of the wire member on the fixture becomes programmed into the wire member, and cooled.

Abstract: An implantable system for the defibrillation of the atria of a patient's heart includes a pair of atrial defibrillation electrodes configured for delivering a first atrial defibrillation pulse in the heart, and a pulse generator operatively associated with the first pair of atrial defibrillation electrodes for delivering the first atrial defibrillation pulse. The pulse generator delivers a second second atrial defibrillation pulse after the first defibrillation pulse without intervening monitoring thereof to reduce the voltage necessary for the shock, and the pain associated therewith.

Abstract: An implantable system for the defibrillation or cardioversion of the heart of a patient in need of such treatment comprises a plurality of primary electrodes, a power supply, and a control circuit. Preferably, at least one auxiliary electrode is also included. The plurality of primary electrodes are configured for delivering a defibrillation pulse along a predetermined current pathway in a first portion of the heart, the current pathway defining a weak field area in a second portion of the heart. The at least one auxiliary electrode is configured for delivering an auxiliary pulse to the a portion of the heart where the primary shock field intensity is at or near a minimum.

Abstract: An implantable system for the defibrillation or cardioversion of the atria and the ventricles of a patient's heart comprises: a first catheter configured for positioning in the right ventricle of the heart; a second catheter configured for positioning through the coronary sinus ostium and in the coronary sinus of the heart, with the first and second catheters together carrying at least three defibrillation electrodes; a power supply; anda control circuit operatively associated with the power supply and the electrodes. The control circuit is configured for delivering an atrial defibrillation pulse through at least two of the electrodes, or a ventricular defibrillation pulse through at least two of the electrodes.

Abstract: A device is disclosed for reducing the likelihood of cardiac arrhythmia or halting the arrhythmia after it begins without having to give a large shock which can be painful or may damage the heart. The device includes an elongated primary strip having a plurality of electrodes positioned at spaced intervals along its length. The strip is dimensioned so that, upon insertion into a patient, the electrodes on the strip electrically contact the heart tissue, either directly or through an intermediate high resistance conductive layer. The electrodes are then energized with an electrical energy sufficient to hyperpolarize heart tissue adjacent to each of the electrodes. Furthermore, the electrodes are spaced along the strip sufficiently close to each other so that, upon energization of the electrodes, a line of heart tissue is hyperpolarized to thereby prevent cardiac electrical conductance across that line. Optionally, secondary electrode strip(s) extend alongside, or encircle, the primary strip.

Abstract: An electrode catheter is disclosed for creating a linear lesion in heart tissue of a heart chamber in order to correct cardiac arrhythmia. The catheter is elongated in dimension such that, upon insertion of the catheter in the patient, the catheter substantially continuously contacts either the endocardial or epicardial heart tissue. The catheter includes a plurality of electrodes and the electrodes are positioned at spaced intervals along the catheter. The electrodes are then sequentially energized with a radio frequency in conjunction with a back plate attached to the patient such that the electrodes form a continuous lesion conforming in shape to the shape of the catheter on the heart tissue. This lesion, furthermore, is of sufficient depth such that the lesion interrupts electrical nodal conduction across the lesion.

Abstract: The present invention provides apparatus and methods for delivering an optimum electrical shock in treating cardiac arrhythmias. The invention comprises apparatus for producing an electrical waveform signal at least at two electrodes. The voltage or current of the signal is then detected to determine the signal time constant. The signal time constant is then used in conjunction with a model time constant to determine when the peak amplitude is reached. The waveform is then interrupted when the peak amplitude is reached. Also provided are methods of selecting a cardiac defibrillator by measuring the impedance of implanted electrodes and then selecting a defibrillator having a capacitor which provides an RC time constant equal to that of a model time constant.

Abstract: Arrhythmia is prevented by detecting a high risk of arrhythmia and then stimulating afferent nerves to prevent the arrhythmia. By monitoring the sympathetic and parasympathetic nerve activity of a patient the risk of arrhythmia may be assessed. An apparatus for monitoring of parasympathetic and sympathetic nerve activity and stimulating the afferent nerves may be implanted in a patient. Furthermore, the apparatus and method for the prevention of arrhythmia may be combined with apparatus for the treatment of arrhythmia through electric shock to facilitate treatment and prevent reoccurrence of arrhythmia.

Abstract: An implantable defibrillator/cardioverter which generates a biphasic defibrillation/cardioversion waveform including a pulse generator comprising two capacitors and a pair of switches for connecting the capacitors in parallel during a first phase and in series during a second phase. The first phase has a small "tilt" between the leading edge voltage and the trailing edge voltage. The second phase has a leading edge voltage which is approximately twice the trailing edge voltage of the first phase.

Abstract: A cardiac pacing apparatus and method. A cardiac pacing apparatus (24) provides a cardiac pacing signal to a plurality of electrode pairs (20, 22), each comprising a positive electrode (20a, 22a) and a negative electrode (20b, 22b). A plurality of isolated current sources (30, 32) supply the electrode pairs with separate electric pacing currents, each small enough in magnitude so as to avoid patient discomfort or burning. The plurality of pacing currents delivered to the electrode pairs add to produce a total cardiac pacing current of sufficient magnitude to cause contraction of a heart muscle through which the pacing currents flow.

Abstract: A closed-heart method for treating ventricular tachycardia in a myocardial infarct patient afflicted with ventricular tachycardia is disclosed. The method comprises, first, defining a thin layer of spared myocardial tissue positioned between the myocardial infarct scar tissue and the inner surface of the myocardium (the endocardium) of the patient, and then ablating the thin layer of spared myocardial tissue by a closed-heart procedure with an ablation catheter. Apparatus for carrying out the method is also disclosed,Also disclosed is a method for prognosing the likelihood of ventricular tachycardia occuring in a myocardial infarct patient not previously diagnosed as afflicted with ventricular tachycardia. The method comprises detecting a thin layer of spared myocardial tissue positioned between the myocardial infarct scar tissue and the inner surface of the myocardium (the endocardium) in the patient.

Abstract: A method and apparatus for delivering a waveform, including a predetermined series of electrical pulses, to the heart by electrodes positioned adjacent the heart. In a first embodiment of the invention, a series of four electrical pulses are delivered from an electrical pulse generator including a charged storage capacitor through two pairs of electrodes and define a waveform comprising two interleaved biphasic signals. The series of electrical pulses have a low defibrillation threshold and require a relatively small amount of energy.In a second embodiment of the invention, a triphasic waveform is applied to the heart through four electrodes. One of the pulses in the triphasic waveform is generated by all four electrodes and in a polarity opposite that of the other two pulses. The pulse generated by all four electrodes may be applied first, second, or third in the series of electrical pulses.

Abstract: A closed-heart method for treating ventricular tachycardia in a myocardial infarct patient afflicted with ventricular tachycardia is disclosed. The method comprises, first, defining a thin layer of spared myocardial tissue positioned between the myocardial infarct scar tissue and the inner surface of the myocardium (the endocardium) of the patient, and then ablating the thin layer of spared myocardial tissue by a closed-heart procedure with an ablation catheter. Apparatus for carrying out the method is also disclosed.Also disclosed is a method for prognosing the likelihood of ventricular tachycardia occuring in a myocardial infarct patient not previously diagnosed as afflicted with ventricular tachycardia. The method comprises detecting a thin layer of spared myocardial tissue positioned between the myocardial infarct scar tissue and the inner surface of the myocardium (the endocardium) in the patient.

Abstract: A cardioversion/defibrillation system employing a dual biphasic and multi-electrode discharge technique for effectively defibrillating the heart by creating a voltage gradient throughout substantially all of the heart which is above a critical voltage gradient while delivering a minimum energy shock. Effective cardioversion/defibrillation is accomplished by delivering two shocks to the heart. The first shock is at an energy level lower than that typically necessary to cardiovert/defibrillate the heart alone, and is applied between a first pair of cardioversion/defibrillation electrodes. The second shock is at an energy less than the first shock and is applied between a second pair of electrodes to shock the area of the myocardium provided with an inadequate voltage gradient from the first shock. The voltage gradient in the low gradient areas is boosted above the minimum gradient necessary to defibrillate.

Abstract: A system for determining the defibrillation threshold energy of a defibrillation lead arrangement by shocking the heart during the T wave of the ECG at decreasing energy levels until the heart is placed in fibrillation. The lowest energy level tested which fails to place the heart in fibrillation correlates to the defibrillation threshold energy of the lead arrangement.

Abstract: A pair of defibrillation patch electrodes is adapted for close fitting placement over the ventricles of the heart, either epicardially or pericardially. One of the patches is contoured to fit over the right ventricle, and the other is contoured to fit over the left ventricle in spaced relationship to the first patch to form a substantially uniform gap between confronting borders of the two. The gap is sufficiently wide to avoid the shunting of current between edges of the patches upon delivery of defibrillation shocks, as well as to accommodate the ventricular septum and the major coronary arteries therein. The size and shape of the patches is such that they encompass most of the ventricular myocardium within and between their borders, to establish a nearly uniform potential gradient field throughout the entire ventricular mass when a defibrillation shock is delivered to the electrodes. Flat versions of the two electrodes provide ease of manufacture.

Abstract: In a method and apparatus for defibrillating a heart in fibrillation, the onset of fibrillation of the heart is detected, and a biphasic waveform having only a first phase and a second phase is applied to the fibrillating heart. Each phase of the waveform is characterized by a predetermined time duration and by a predetermined polarity and magnitude of voltage, the duration of the first phase being greater than the duration of the second phase, and the initial voltage magnitude of the first phase being greater than that of the second phase. The biphasic waveform is applied by delivering it to a pair of patch electrodes affixed over and contoured to conform substantially to the surface of the right and left ventricles, respectively. The patch electrodes are affixed to either the epicardium or the pericardium. The left ventricular patch electrode is used as the cathode for the first phase of the applied biphasic waveform, and as the anode for the second phase.