Surgery: light – thermal – and electrical application – Light – thermal – and electrical application – Electrical energy applicator
Reexamination Certificate
2000-03-03
2002-10-08
Jastrzab, Jeffrey R. (Department: 3762)
Surgery: light, thermal, and electrical application
Light, thermal, and electrical application
Electrical energy applicator
C600S374000
Reexamination Certificate
active
06463335
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the field of cardiac stimulation, and more specifically to the field of stimulating cardiac tissue using a medical electrical lead.
BACKGROUND OF THE INVENTION
Atrial arrhythmias and supra ventricular tachycardias, such as atrial fibrillation, atrial flutter and atrio-ventricular re-entry, are common post-operative complications among heart surgery patients. It is estimated that during the first seven to ten days after cardiac surgery post-operative supra ventricular tachycardia occurs in up to 63 percent of patients. Aranki et al. showed that patients with postoperative atrial fibrillation have a mean hospital stay of about fifteen days, whereas those patients without post-operative atrial fibrillation have a mean hospital stay of about ten days. Whether such extended hospitalization stays are primarily caused by arrhythmias is not known. See Cardiac Surg. Kirklin J W, Barrat-Boyes BC (Eds.): NY 1993, pg. 210, “The Importance of Age as a Predicator of Atrial Fibrillation and Flutter after Coronary Artery Bypass Grafting”, Leitch et al., J. Thorac. Cardiovasc. Surg., 1990:100:338-42; “Atrial Activity During Cardioplegia and Postoperative Arrhythmias”, Mullen et al., J. Thorac. Cardiovasc. Surg., 1987:94:558-65.
The presence of such arrhythmias, which in otherwise healthy patients may not be unduly serious, may be especially harmful to heart surgery patients. The surgery itself, the effects of prolonged anesthesia, or both have often already compromised the hemodynamic condition of such patients. Drugs that might be used to prevent post-operative atrial fibrillation are often only partially effective and may have negative effects on cardiac pump function.
Supra ventricular tachycardias may further cause a very irregular ventricular rate, which in turn can lead to hemodynamic conditions deteriorating even further. Such deterioration is especially serious for patients having a compromised left ventricular function. Such complications may also present a serious impediment to the recovery of the patient. See, for example, “Maintenance of Exercise Stroke Volume During Ventricular Versus Atrial Synchronous Pacing: Role of Contractility”, Ausubel et al., Circ., 1985:72(5):1037-43; “Basic Physiological Studies on Cardiac Pacing with Special Reference to the Optimal Mode and Rate After Cardiac Surgery”, Baller et al., Thorac. Cardiovasc. Surg., 1981:29:168-73.
If post-operative atrial fibrillation proves to have unacceptable hemodynamic consequences or causes serious symptoms, and if it does not stop spontaneously or antiarrhythmic drugs are ineffective in treating it, external cardioversion or atrial defibrillation may be required. But external atrial defibrillation, although generally effective as a treatment, may have profound side effects. First, and in contrast to ventricular defibrillation where conversion to normal sinus rhythm may occur after the first shock, atrial defibrillation may not be obtained until after several shocks have been delivered to the patient. This is because ventricular contraction continues during supra ventricular tachycardia. Due to the large amounts of energy, which must be delivered in external defibrillation (e.g., 40 to 360 Joules), the shocks are not tolerated well by conscious patients. External defibrillation is therefore preferably performed under general anesthesia or at least when the patient is sedated. The use of anesthesia gives rise to yet another patient risk factor.
External defibrillation requires relatively high energy because the electrical source is not positioned directly upon the cardiac tissue and instead must pass through the thorax, which tends to dissipate the energy. In contrast, internally applied atrial defibrillation, such as may occur during surgery through defibrillation paddles placed directly on the heart, requires considerably less energy because the defibrillation electrical energy is applied only to the tissue that needs to be defibrillated. In fact, direct atrial defibrillation may be accomplished with only one-Joule pulses in contrast to the 40 Joule and greater pulses required for external defibrillation. See, for example, Kean D., NASPE abs. 246, PACE, April 1992, pt. II, pg. 570.
Defibrillation success rates generally depend on the amount of energy delivered. The lower amount of energy delivered, the lower the defibrillation success rate and the greater the number of shocks that must be applied to obtain successful defibrillation. By way of contrast, in direct atrial defibrillation, where energy is applied directly to the heart, the energy level can be selected such that the patient may more easily tolerate both the amount of energy delivered as well as the number of shocks required.
Waldo et al. in “Use of Temporarily Place Epicardial Atrial Wire Electrodes For The Diagnosis and Treatment of Cardiac Arrhythmias Following Open-Heart Surgery,” J. Thorac. Cardiovasc. Surg., 1978, vol. 76, no. 4, pp. 558-65 disclose the use of a pair of temporary heart wires placed on the atrium to diagnose and treat arrhythmias through anti-tachycardia overdrive pacing. Temporary heart wires were sutured to the atrial walls at the time of the heart surgery. Once the patient was ready to be released from hospital, the wires were removed by traction or pulling upon the external end. See, for example, the temporary medical lead disclosed in U.S. Pat. No. 5,527,358 entitled “Temporary Medical Electrical Lead” to Mehmanesh et al.
Immobilization of mounting pads for electrical leads on the epicardium is currently accomplished by suturing the pad to the tissue, a potentially time-consuming process which can also cause damage to the patient's myocardial tissue. Moreover, when the electrode of a lead is removed, the sutures and mounting pad remain within the patient, or must be removed from the patient. When non-biodegradable pads or sutures are employed, a foreign body response is typically elicited from the patient's immune system. Such a response typically leads to scar tissue embedding the implanted electrode mounting pad or other components. The scar tissue may affect the performance of the patient's myocardial tissue. Thus, there exists a need to provide an improved temporary medical lead which may be attached to and removed from a patient's epicardium more quickly, which may be attached to and removed from the epicardium with less trauma occurring to a patient's cardiac tissue, and which provokes a less severe response form the human body.
Various devices, compositions and methods relating peripherally or directly to the present invention are described in the patents and technical papers listed in Tables 1 and 2 below.
TABLE 1
PATENTS
U.S. Pat. No.
Inventors
Issue Date
5,964,724
Rivera et al.
October 12, 1999
5,964,690
Wright et al.
October 12, 1999
5,961,484
Gusakov et al.
October 5, 1999
5,942,406
Burton et al.
August 24, 1999
5,936,035
Rhee et al.
August 10, 1999
5,928,142
Cartmell et al.
July 27, 1999
5,900,245
Sawhney et al.
May 4, 1999
5,883,078
Seelich et al.
March 16, 1999
5,824,230
Holm et al.
October 20, 1998
5,817,303
Stedronsky et al.
October 6, 1998
5,804,428
Edwardson et al.
September 8, 1998
5,785,040
Axelgaard
July 28, 1998
5,773,418
Edwardson et al.
June 30, 1998
5,770,194
Edwardson et al.
June 23, 1998
5,763,411
Edwardson et al.
June 9, 1998
5,763,410
Edwardson et al.
June 9, 1998
5,750,657
Edwardson et al.
May 12, 1998
5,739,288
Edwardson et al.
April 14, 1998
5,733,545
Hood, III
March 31, 1998
5,691,152
Burton et al.
November 25, 1997
5,643,596
Pruss et al.
July 1, 1997
5,605,541
Holm
February 25, 1997
5,552,452
Khadem et al.
September 3, 1996
5,549,904
Juergensen et al.
August 27, 1996
5,496,872
Constancis et al.
March 5, 1996
5,459,177
Miyakoshi et al.
October 17, 1995
5,412,076
Gagnieu
May 2, 1995
5,407,671
Heimburger et al.
April 18, 1995
5,405,366
Fox et al.
April 11, 1995
4,909,251
Seelich
March 20, 1990
4,900,554
Yanagibashi et al.
February 13, 1990
4,848,353
Engel
July 18, 1989
4,804,691
English et al.
February 14, 1989
4,600,5
Hendriks Marc
Münch Kuno
Verhoeven Michel
Berry Tom G.
Jastrzab Jeffrey R.
Medtronic Inc.
Oropeza Frances P.
Waldkoetter Eric R.
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