FIELD OF THE INVENTION
[0002] This invention relates to methods and apparatus for electrically assisting the normal contraction of the heart.
BACKGROUND
[0003] Congestive heart failure is characterized by the gradual inability of the heart to maintain optimal circulation to the body and its representative organs. Common symptoms of congestive heart failure include difficulty in breathing, chest discomfort, profound fatigue, and swelling of the ankles.
[0004] Congestive heart failure typically develops in an insidious pattern. In initiation of this maldevelopment, the heart cell, known as a cardiomyocyte, begins to lose its ability to contract and reset itself in a linear pattern. The subsequent inability of the cardiomyocyte to respond to physiologic demand sets in motion a deleterious cascade of compensatory physiologic phenomena.
[0005] Current clinical treatements include drug therapy, surgery, restraint devices, and electrical stimulation. Current drug therapy includes aspirin, beta blockers, dihydropyridine and mixed calcium channel blockers, thiazide and loop diuretics, digitalis, angiotensin converting enzyme inhibitors, nitrates, angiotensin two converting enzyme receptor blockers, human B-type natriuretic peptide infusion, aldosterone antagonists, and others. By its inherent nature, pharmacologic interventions will continue to advance safely but slow. Drug therapy has made little, if any, headway in the overall incidence and prevalence of congestive heart failure.
[0006] Surgical methods for addressing advanced failure related states and postinfarction phenomena include ventriculectomy procedures. These procedures involve surgical reduction of nonviable and/or marginally viable myocardium, rendering the heart physically and functionally smaller. The Batista operation specifically attempts immediate geometric remodeling of the failing myocardium with mixed results.
[0007] Another treatment modality for congestive heart failure involves the use of restraint devices. These devices restrain further mechanical degradation of the cardiomyocyte in established failure states but do not address autonomic insufficiency (electrical degradation).
[0008] Heart transplantation will likely remain superior to this approach but is limited by a continued disparity in donated hearts, insurance coverage, and rejection issues.
[0009] Left Ventricular Assist Devices are a highly promising emerging field which are very expensive and necessarily plagued with a multitude of moving parts. Lifelong permanent anticoaglation with warfarin will be necessary for many of these patients.
[0010] Electrical pacing of the heart has now reached a worldwide industry standard. Pacing began as an isolated single electrical stimulus designed to overdrive fatal bradycardia, a dangerously low heart rate. Understanding of the deterioration of the QRS interval in failure states has led to further innovation in addressing electromechanical failure. Current biventricular pacing modalities seek to correct this delay.
[0011] What is clearly needed, therefore, is improved methods and apparatus to more completely augment the cardiac functioning of patients suffering from congestive heart failure.
SUMMARY
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