Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Reexamination Certificate
2000-11-22
2004-02-10
Ruhl, Dennis W. (Department: 3737)
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
C600S437000, C604S096010, C606S001000, C606S192000
Reexamination Certificate
active
06689062
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to a minimally invasive approach to perform transesophageal cardiovascular and mediastinal procedures. More specifically, the invention relates to implementing the concept of transesophageal access to the heart, great vessels and related structures. The invention describes devices and methods to create a transesophageal access to the heart and surrounding structures to perform a body of surgical procedures within a beating heart and on other surrounding structures.
BACKGROUND OF THE INVENTION
The access to the human heart has always been a source of active research especially recently with the advancement in technology that has led to improved management of cardiovascular pathology. Heart disease is the leading cause of death connected to all age groups in the United States. The esophagus has a close proximity to the heart and posterior mediastinum, which has allowed the use of transesophageal fine needle aspiration and transesophageal biopsy techniques to be used extensively in recent years to obtain tissue samples. Most of the posterior mediastinal tissues are accessible for biopsy including the lungs and lymph nodes. The technique has proven to be safe and reproducible with minimal complications. The microbial flora of the human esophagus is similar to that in the pharynx, which results in no bacterimia with transesophageal puncture using needles up to 1 mm in diameter in many studies. The esophagus has never been used to access the human heart, but rather to perform procedures related to the heart due to the close anatomical proximity. A number of trials have been described as in U.S. Pat. No. 6,120,442 for transesophageal intracardiac pressure measurement, in U.S. Pat. No. 5,417,713 for using a transesophageal defibrillating system, and in U.S. Pat. No. 5,179,952 for the use of a transesophageal electrocardial stimulator. Some trials were made to use the trachea for monitoring the heart as in U.S. Pat. No. 5,080,107 that describes the use of an endotracheal sensor for cardiac monitoring.
Access to the heart has always been the main determinant of the form, degree and invasiveness of therapy, which determines the ultimate success of the treatment modality. The left side of the heart is more systemically important and much less accessible than the right side for its anatomic location and the high blood pressure it generates in the systemic circulation. The spectrum of disease states that can be assessed diagnostically or therapeutically are generally more reflected on the left side of the heart. This is evident clinically in a wide range of cardiovascular pathology e.g. congestive heart failure. There is no known non-invasive method that can directly measure the pressure in any chamber of the heart. All current methods either use speed of blood flow as a non-invasive reflection of chamber pressure or they measure the pressure invasively via a catheter inside or near the chamber. The most common technique to measure the left atrial pressure is the pulmonary catheter wedge pressure method. The left atrium is a low-pressure, left-sided structure that has a special importance with regard to its mechanical and electrical properties. Unfortunately, there is no simple non-invasive way of directly measuring the left atrial pressure. Even with invasive measurement as in pulmonary artery catheterization, the measured value reflects an indirect estimation of the left atrial pressure, and thus can be inaccurate in many instances. The left atrium is also important in terms of electrophysiological mapping and ablation. The current techniques access the left atrium using a catheter indirectly from the right atrium across the inter atrial septum or in a retrograde approach through the aorta. Both techniques have their inherent side effects and complications. Thus, access to the left atrium is a described objective in order to treat a large subset of patients, such as congestive heart failure patients.
A second subset of cardiac patients in which the access to the heart is the main determinant of interventions and management are patients with congenital cardiac defects like ASD, VSD and PDA. The main pathology in most congenital cardiac defects is the presence of an unnatural conduit that shunts the blood from the right to left heart or the reverse. This overloads the side with lower pressure and any tissue or vascular bed in the shunted circuit. The pulmonary vascular bed is commonly affected by blood overflow that may lead to reversible or late irreversible pulmonary vascular hypertension. The in vasiveness of the current techniques limits the early implementation of a shunt closure especially in children, which is a curative intervention if done before irreversible vascular changes. Other techniques use the catheter transvascular approach with limited success due to lack of control and torque at the end of a long flexible, narrow catheter used in the procedure.
In a third group of patients, cardiac arrhythmias are responsible for a high percentage of morbidity and mortality. Atrial fibrillation is a common and chronic disease with a prevalence of 2-3% in the United States. The disease is longstanding and mandates chronic anticoagulation as part of the treatment to prevent any embolic disease especially to the brain. Chronic anticoagulation in itself carries serious risk of internal bleeding added to the toxicity of chronic anti-arrhythmic medications used to stabilize atrial fibrillation. Recently, surgical curative techniques have been described in the literature to treat atrial fibrillation. Access to the heart has been a main determinant in the use of any of these techniques. The invasiveness of the open chest approach has limited the number of the Maze-like procedures used to radically prevent the fibrillation impulses from being conducted to the ventricles. Also, the catheter-based approach is inaccurate, tedious, time consuming (up to 12 hours) and not definitive in creating enough linear ablations to prevent impulse conduction. The thoracoscopic approach is easier than the catheter-based transvascular approach but the side access to the posterior heart limits the linearity of ablation especially around the entrance of the pulmonary veins, which results in incomplete Maze, and recurrence of the disease. The three known accesses to the heart namely, the open chest, the catheter-based transvascular, and the thoracoscopic approaches suffer from serious limitations and complications which, in turn, limit the therapeutic options for most of patients. The limitations of the current three known accesses to the human heart can be classified as follows:
1—The Open-chest Technique
Most cardiovascular procedures are performed by opening the chest wall either by gross sternotomy or by lateral thoracotomy. The sternotomy approach is more common than the lateral thoracotomy as it allows greater field for the surgeon to introduce surgical devices, to control target tissues and to clamp and catheterize the aorta for induction of cardioplegia and bypass. It involves opening the sternum using a saw to cut through the bony structure. It also involves arresting the heart by cardioplegic techniques. The circulation is switched to cardiopulmonary bypass for preserving tissue perfusion. The above advantages of the stemotomy approach are offset by serious disadvantages. First, the risk of stopping the circulation with the possibility of causing marked decrease in tissue perfusion or ischemic damage that may involve vital tissues like the brain, heart or kidneys. Second, the risk of embolization of dislodged tissues in the aorta due to aortic manipulation including clamping and catheterization. The dislodged emboli can cause acute brain or peripheral ischemia. Brain damage may be permanent after an embolic event during open sternotomy approach. Even without any embolic or gross brain injury, psychometric analysis shows definite changes and cognitive defects in young healthy individuals after open-heart surgery. Third, opening the chest wall by
Cesari and McKenna LLP
Jung William C.
Microaccess Medical Systems, Inc.
Ruhl Dennis W.
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