Endovacular cardiac venting catheter and method

Details Endovacular cardiac venting catheter and method Endovacular cardiac venting catheter and method

1999-06-25

2003-06-17

Mendez, Manuel (Department: 3763)

Surgery

Means for introducing or removing material from body for...

Treating material introduced into or removed from body...

Reexamination Certificate

active

06579259

ABSTRACT:

FIELD OF THE INVENTION
This invention relates generally to devices and methods for performing cardiovascular, pulmonary and neurosurgical procedures wherein the patient is placed on cardiopulmonary bypass. More specifically, the invention relates to devices and methods for venting blood and other fluids from the heart while the heart is under cardioplegic arrest and the patient is on cardiopulmonary bypass.
BACKGROUND OF THE INVENTION
Various cardiovascular, neurosurgical, pulmonary and other interventional procedures, including repair or replacement of aortic, mitral and other heart valves, repair of septal defects, pulmonary thrombectomy, coronary artery bypass grafting, treatment of aneurysms, and neurovascular procedures, may require general anesthesia, cardiopulmonary bypass, and arrest of cardiac function. In order to arrest cardiac function, the heart and coronary blood vessels must be isolated from the remainder of the circulatory system. Using current techniques, isolation of the heart and coronary blood vessels is accomplished by placing a mechanical cross-clamp externally on the ascending aorta downstream of the ostia of the coronary arteries, but upstream of the brachiocephalic artery. A catheter is then inserted directly into the ascending aorta between the cross-clamp and the aortic valve, and cardioplegic fluid is infused through the catheter into the ascending aorta from which it flows into the coronary arteries to perfuse the myocardium. An additional catheter may be introduced into the coronary sinus for retrograde perfusion of the myocardium with cardioplegic fluid. In addition, the myocardium is usually cooled by irrigating with cold saline solution and/or application of ice or cold packs to the heart. Cardiac contractions will then cease.
While the heart is stopped, circulation is maintained throughout the body by a cardiopulmonary bypass system. A venous cannula is placed in a major vein such as the inferior vena cava in order to withdraw deoxygenated blood from the body. The deoxygenated blood is directed to a blood oxygenator which restores the blood with oxygen, and the oxygenated blood is pumped back into a major artery downstream of the aortic cross-clamp through an arterial return cannula.
Although the patient is on cardiopulmonary bypass, a certain amount of blood not withdrawn through the venous cannula returns through the venous system to the heart. In addition, cardioplegic fluid delivered into the coronary arteries drains back into the heart through the coronary sinus. Therefore, the heart must be vented to prevent an excessive quantity of blood and other fluids from pooling in the heart while it is not beating. To accomplish this, a venting cannula may be introduced through the aortic wall into the aorta upstream of the cross-clamp to withdraw fluid from the aortic root. Alternatively, a venting cannula may be introduced through a wall of the pulmonary artery near the point at which it connects to the right ventricle of the heart to allow blood to be withdrawn from the pulmonary artery. In procedures in which the heart itself is surgically opened, a venting cannula may be introduced directly into the heart through the incision in the heart wall.
Known techniques for performing major surgeries such as coronary artery bypass grafting and heart valve repair and replacement have generally required open access to the thoracic cavity through a large open wound, known as a thoracotomy. Typically, the sternum is cut longitudinally (a median sternotomy), providing access between opposing halves of the anterior portion of the rib cage to the heart and other thoracic vessels and organs. An alternate method of entering the chest is via a lateral thoracotomy, in which an incision, typically 10 cm to 20 cm in length, is made between two ribs. A portion of one or more ribs may be permanently removed to optimize access.
In procedures requiring a median sternotomy or other type of thoracotomy, the ascending aorta is readily accessible for placement of an external cross-clamp, and for introduction of a cardioplegic fluid delivery cannula and venting cannula through the aortic wall. The pulmonary artery is exposed as well to allow introduction of a venting catheter through the pulmonary arterial wall. However, such surgery often entails weeks of hospitalization and months of recuperation time, in addition to the pain and trauma suffered by the patient. Moreover, while the average mortality rate associated with this type of procedure is about two to fifteen per cent for first-time surgery, mortality and morbidity are significantly increased for reoperation. Further, significant complications may result from such procedures. For example, application of an external cross-clamp to a calcified or atheromatous aorta may cause the of release of emboli into the brachiocephalic, carotid or subclavian arteries with serious consequences such as strokes.
Methods and devices are therefore needed for isolating the heart and coronary arteries from the remainder of the arterial system, arresting cardiac function, venting the heart, and establishing cardiopulmonary bypass without the open-chest access provided by a median sternotomy or other type of thoracotomy. In particular, methods and devices are needed which facilitate venting the heart sufficiently to allow the heart to be placed under cardioplegic arrest with full cardiopulmonary bypass, without requiring open-chest access to the heart and without requiring an incision or puncture in the aorta, in the pulmonary artery, or in the heart wall.
The descriptive terms downstream and upstream, when used herein in relation to the patient's vasculature, refer to the direction of blood flow and the direction opposite that of blood flow, respectively. In the arterial system, downstream refers to the direction further from the heart, while upstream refers to the direction closer to the heart, with the opposite true in the venous system. The terms proximal and distal, when used herein in relation to instruments used in the procedure, refer to directions closer to and farther away from the operator performing the procedure.
SUMMARY OF THE INVENTION
The present invention is directed to an endovascular approach for preparing a patient's heart for cardiac procedures which does not require a grossly invasive thoracotomy. The invention facilitates venting fluids from a patient's heart while the heart is placed under cardioplegic arrest and circulation is maintained by a cardiopulmonary bypass system without necessitating a median sternotomy or other thoracic incision and without requiring punctures or incisions in the heart, aorta, pulmonary artery, or other vessels.
In a first aspect of the invention, a venting catheter is provided for withdrawing blood from a pulmonary artery connected to a right ventricle of a patient's heart. The venting catheter comprises a flexible elongate shaft having a distal end, a proximal end, and an inner lumen extending from the proximal end to an inlet port at the distal end. Usually, a plurality of inlet ports are provided at the distal end in communication with the inner lumen. The shaft has a length selected to allow the distal end to be positioned in the pulmonary artery with the proximal end extending transluminally to a peripheral vein and out of the patient through a puncture in the peripheral vein. Usually, the shaft is at least about 40 cm in length to allow the venting catheter to be introduced into the internal jugular vein in the neck and advanced into the pulmonary artery via the superior vena cava. The inner lumen is configured to allow blood to be withdrawn from the pulmonary artery at a rate of at least 50 ml/min. at a pressure no lower than −350 mmHg. In a specific embodiment, the inner lumen has cross-sectional area of at least 4.0 mm
2
.
In a preferred embodiment, the venting catheter may include an expandable member mounted to the shaft near the distal end. The expandable member may serve several purposes. The expandable member may be configured to be carried by

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