Cardiac bypass catheter system and method of use

Details Cardiac bypass catheter system and method of use Cardiac bypass catheter system and method of use

1999-07-21

2003-06-24

Sykes, Angela D. (Department: 3762)

Surgery

Devices transferring fluids from within one area of body to...

C604S096010, C604S101010, C604S101050, C604S919000

Reexamination Certificate

active

06582388

ABSTRACT:

TECHNICAL FIELD
The present invention is a surgical device assembly. More particularly, it is a catheter system which is adapted to provide artificial systemic blood circulation while temporarily arresting the heart and substantially isolating the heart from the systemic circulation in order to perform surgical procedures on the heart.
BACKGROUND
Various abnormalities of the heart are generally treated by temporarily arresting the heart from beating, isolating the heart from systemic blood circulation, supporting the systemic blood circulation via an external cardiopulmonary bypass pump, and performing surgical operations directly on the stopped heart. This general method is herein referred to as a “cardiac bypass procedure”. Examples of such cardiac bypass procedures include, without limitation: coronary artery bypass graft surgery (“CABG”); valve replacement surgery; cardiac transplantation surgery; and a procedure known as the “maze” procedure wherein conduction blocks are surgically formed in the wall of one or both of the atria in order to prevent atrial fibrillation.
Conventional techniques in performing such “cardiac bypass procedures” generally include cutting through the sternum in the chest cavity using well known “sternotomy” techniques, spreading open the rib cage, retracting the lungs from the region of the heart, and directly exposing the heart to the surgeon. One of various known cardioplegia agents may be used to temporarily arrest the heart from beating. Further to the bypass procedure, an external cross clamp is generally used to occlude the aorta in the region of the arch between the aortic root and the carotid arteries. With the cross-clamp in this position, both the left heart chambers and the coronary arteries into the heart are isolated from the systemic arterial circulation while the carotid arteries are fed with the blood flow from the bypass pump. In addition, flow from the superior and inferior vena cava is also temporarily diverted from the heart to the pump, usually by externally tying the vena caval walls onto venous pump cannulae.
Minimally Invasive Cardiac Bypass Catheter Systems
Recent advances have been made in the field of “cardiac bypass procedures” which include the use of novel catheter assemblies which are adapted to temporarily arrest and bypass the heart without the need for direct cross-clamping or externally tying the vena cavae. Such assemblies are generally herein referred to by the terms “minimally invasive catheter bypass systems,” or derivatives of these terms, and generally include an arterial catheter, which isolates the left heart chambers from systemic arterial circulation beyond the aortic root, and a venous catheter, which isolates the right heart chambers from venous circulation from the vena cavae. Further to the intended meaning, such minimally invasive catheter bypass systems may be used during procedures which otherwise still require a sternotomy in an otherwise “open chest” or “open heart” procedure which directly exposes the heart, as well as during procedures which otherwise alleviate the need for such sternotomies, such as for example procedures known as “port access” procedures.
One particular example of a previously known “minimally invasive cardiac bypass system” uses an arterial catheter which occludes the aorta from systemic arterial circulation with an inflatable balloon located on the outside surface of the catheter's distal end portion which is positioned within the aorta. The arterial catheter further includes a cannula with lumens and distal ports which provide for cardioplegia agent delivery and venting of the left ventricle, respectively, while the heart is isolated from systemic circulation with the inflated balloon on the outer surface of the arterial catheter. Further to this known system, a venous catheter is further provided and uses a balloon in each of the superior and inferior vena cava. The venous catheter balloons inflate to occlude these great veins and thereby isolate the right heart chambers from systemic venous blood flow. Moreover, the venous and arterial catheters which combine to form minimally invasive cardiac bypass catheter systems engage to inlet and outlet ports, respectively of a cardiopulmonary bypass pump, which pump may be further considered a part of the overall system. One such known pump which is believed to be particularly usefull in cardiac bypass procedures, including minimally invasive bypass procedures, is known as the “BioPump”, Model Number “BP80”, which is available from Medtronic, Inc.
Further to the description for the minimally invasive cardiac bypass system example just provided above, the terms “proximal” and “distal” are herein used throughout this disclosure as relative terms. In the context of describing a device or catheter used in such a system, the term “proximal,” such as in the phrase “proximal end”, is herein intended to mean toward or closer to a user such as a physician, whereas the term “distal,” such as in the phrase “distal end” is herein intended to mean away from or further away from the user. However, if and where the terms “proximal” and “distal” are herein used in the context of describing anatomical structures of the cardiovascular system or physiological blood flow, the term “proximal” is herein intended to mean toward or closer to the heart, whereas the term “distal” is herein intended to mean away from or further from the heart. Furthermore, the terms “upstream” and “downstream” are also relative terms which may be herein used interchangeably with “proximal” or “distal”, respectively, in the anatomical or physiological context just described.
According to the method of using known minimally invasive cardiac bypass catheter systems such as the example summarized above, the heart is usually put on “partial bypass” prior to “complete bypass”. The terms “partial bypass” are herein intended to mean a condition wherein the heart is beating and pumping blood throughout the body's circulation prior to inflating the balloons on the arterial and venous catheters, and wherein some blood is also aspirated from the vena cavae through the venous catheter, sent through the cardiopulmonary bypass pump, and infused into the arterial circulation through the flow ports along the arterial catheter. The terms “complete bypass” or “full bypass” or derivatives thereof are therefore herein intended to mean a condition wherein the heart is substantially isolated from systemic venous and arterial circulation by means provided by the venous and arterial catheters, respectively, such as for example by inflating balloons on the exterior surfaces of such venous and arterial catheters to thereby totally occlude the vena cavae and aorta, also respectively, as described above.
According to these definitions for partial and full bypass just provided, a patient is therefore put on partial bypass by first positioning the venous and arterial catheters at respectively predetermined locations along the vena cavae and aorta, respectively, such that the respective flow ports may provide for the respective aspiration or infusion of blood and such that balloons on the catheter outer surfaces may be thereafter inflated to isolate the right and left heart chambers, also respectively, during fill bypass. The procedure for subsequently weaning a patient from partial bypass to full bypass according to the known minimally invasive cardiac bypass system example described above generally proceeds as follows.
Cardioplegia agent is delivered during partial bypass in order to begin reducing the cardiac function ultimately toward the temporarily arrested state. The external balloons are inflated to occlude the vena cavae and isolate the right heart from systemic venous circulation prior to inflating the arterial catheter's balloon to isolate the left heart from systemic arterial lo circulation. During this “weaning” period, the bypass pump circulates the blood aspirated from the vena cavae while the heart continues to pump a declining volume of residual blood from the coronary

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