Apparatus and methods for treating venous compression/obstruction syndromes

Abstract

Apparatus and methods are provided for treating patients exhibiting symptoms of hypertension, isolated systolic hypertension, heart failure with preserved ejection fraction, May-Thuner Syndrome or dyspnea by diagnosing and reducing narrowing of a patient's iliac vein caused by extrinsic localized compression using a stent having circumferential differential radial stiffness and delivery catheter for aligning and deploying such stents.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application is a continuation of U.S. patent application Ser. No. 16 / 865,154, filed May 1, 2020, now U.S. Pat. No. 10,881,541, the entire contents of which are incorporated herein by reference.TECHNICAL FIELD[0002]This application relates generally to devices and methods for reducing venous compression / obstruction arising from localized extrinsic loads, and thereby, to provide relief from a number of cardiovascular ailments hypothesized to arise therefrom.BACKGROUND[0003]Hypertension is a disease that affects more than 77.9 million adults in the United States and approximately one billion individuals worldwide. In 2008, elevated blood pressure (BP) affected approximately 40% of adults 25 years of age or greater globally. According to a 2014 report from the American Heart Association (AHA), based on NHANES / NCHS data through 2010, one in three adults has high BP, and 74.9% of these subjects are undergoing treatment for hypertension. The...

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Benefits of technology

[0014]It is the inventor's insight that many illnesses, including MTS, HFpEF and the resulting dyspnea, have as a root cause localized narrowing of the iliac veins caused by compression or obstruction. In particular, it is hypothesized that the foregoing syndromes result or may be exacerbated by extrinsic localized venous compression / obstruction arising from several sources. Such sources of compression / obstruction may be intermittent or continuous, asymmetric, and may include an artery overlying a patient's iliac vein that has age-related reduction in arterial compliance. Such compression also may arise due to exercise or an overriding ligament or bone, or an acquired complication such as uterine fibroids that may cause compression of the patient's iliac veins. It is further hypothesized that venous compression / obstruction reduces blood return to the heart, which in turn may reduce oxygenation in the lungs, and further result in the left heart working harder to maintain sufficient blood pressure. Moreover, the increased venous pressure in the extremities resulting from the venous compression also is believed to increases the arterial pressure, resulting in increased systolic pressure, hypertension and HFpEF.

[0015]In accordance with the principles of the present invention, apparatus and methods are provided for reducing venous compression and obstruction, which expected to improve venous return flow in the lower extremities and reduce the cardiac work required to maintain adequate blood flow. In one preferred embodiment, stents configured for stenting the iliac veins are provided, wherein the stents have variable circumferential stiffness. In particular, such stents include a circumferential portion, suitable for alignment with an overriding artery, ligament or bone that counteracts an extrinsic compressive force. Such circumferential variability in stiffness may be achieved by varying strut thicknesses, geometries, lengths and / or widths around the stent circumference to address the asymmetric nature of applied loads. For example, the stent may have differential radial stiffness disposed over a range of between one-half and one-quarter of the stent circumference. The stent may be formed of a laser-cut metal or metal alloy tube and feature an open cell or closed cell geometry, and may be either self-expanding or balloon expandable. As a further alternative, the inventive stent may comprise a woven or braided material. In addition, the radial stiffness of the inventive stents may vary along a longitudinal direction of the stent. Advantageously, employing variable circumferential stiffness is expected to provide increased longitudinal flexibility to facilitate stent placement, to enhance fracture resistance, and to reduce the risk of potential stenosis.

[0016]In accordance with another aspect of the invention, delivery catheters are provided that facilitate delivery and deployment of the inventive stents. In particular, the delivery catheters include features that enable the stent orientation relative to the overriding compressive artery, ligament or bone to be accurately determined prior to stent deployment. For example, the catheter may include a marker band system, arrayed circumferentially, that allows directional deployment of the stent under fluoroscopic guidance, to align a preferred portion of the differential radial strength and hoop strength against anatomical feature inducing the venous compression. Delivery catheters suitable for use with the stents of the present invention preferably are sufficiently flexible to negotiate tortuous venous anatomy. In addition, preferred delivery catheters also are sufficiently rigid to permit torque applied at the catheter handle to be transmitted to the distal region of the catheter, thereby to orient the directional features of the stent with the anatomical feature inducing the venous compression.

Problems solved by technology

It is further hypothesized that venous compression / obstruction reduces blood return to the heart, which in turn may reduce oxygenation in the lungs, and further result in the left heart working harder to maintain sufficient blood pressure.

Moreover, the increased venous pressure in the extremities resulting from the venous compression also is believed to increases the arterial pressure, resulting in increased systolic pressure, hypertension and HFpEF.

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