Systems and methods for making encapsulated hourglass shaped stents

Abstract

Systems and methods for the manufacture of an hourglass shaped stent-graft assembly comprising an hourglass shaped stent, graft layers, and an assembly mandrel having an hourglass shaped mandrel portion. Hourglass shaped stent may have superelastic and self-expanding properties. Hourglass shaped stent may be encapsulated using hourglass shaped mandrel assembly coupled to a dilatation mandrel used for depositing graft layers upon hourglass shaped mandrel assembly. Hourglass shaped mandrel assembly may have removably coupled conical portions. The stent-graft assembly may be compressed and heated to form a monolithic layer of biocompatible material. Encapsulated hourglass shaped stents may be used to treat subjects suffering from heart failure by implanting the encapsulated stent securely in the atrial septum to allow blood flow from the left atrium to the right atrium when blood pressure in the left atrium exceeds that on the right atrium. The encapsulated stents may also be used to treat pulmonary hypertension.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims priority to U.S. Provisional Patent Application No. 62 / 343,658, filed May 31, 2016, the entire contents of which are incorporated herein by reference.FIELD OF THE INVENTION[0002]This application relates to systems and methods for the manufacture of hourglass or “diabolo” shaped encapsulated stents for treating congestive heart failure and other disorders treated with encapsulated hourglass shaped stents.BACKGROUND[0003]Heart failure is the physiological state in which cardiac output is insufficient to meet the needs of the body and the lungs. Congestive Heart Failure (CHF) occurs when cardiac output is relatively low due to reduced contractility or heart muscle thickening or stiffness. There are many possible underlying causes of CHF, including myocardial infarction, coronary artery disease, valvular disease, and myocarditis.[0004]CHF is associated with neurohormonal activation and alterations in autonomic control....

AI Technical Summary

Benefits of technology

[0024]In accordance with yet another aspect, a method for making an encapsulated stent-graft may involve providing a funnel having a large end and a small end, placing an asymmetric stent with a first end, a second end, an exterior surface and an interior surface within the large end of the funnel, placing a biocompatible tube over the small end of the funnel, the biocompatible tube having a stent receiving portion and a remaining portion, advancing the asymmetric stent through the funnel and out the small end of the funnel, thereby depositing the asymmetric stent into the biocompatible tube such that the stent is positioned within the stent receiving portion of the biocompatible tube, thereby engaging an exterior surface of the asymmetric stent with the biocompatible tube, pulling the remaining portion of the biocompatible tube through the first end of the asymmetric stent and out the second end, introducing a first mandrel having a shape similar to the first side of the asymmetric stent into the first side of asymmetric stent thereby engaging the interior surface of the first side of the asymmetric stent with a portion of the remaining portion of the biocompatible tube, and introducing a second mandrel having a shape similar to the second side of the asymmetric stent into the second side of the asymmetric stent thereby engaging the interior surface of the second side of the asymmetric stent with a portion of the remaining portion of the biocompatible tube.

[0025]In accordance with yet another aspect, an hourglass shaped mandrel assembly for making an encapsulated stent-graft may involve a first portion having at least a first conical region having a flared end with a first diameter and an apex end with a second diameter, a second portion having at least a second conical region having a flared end with third diameter and an apex end with a fourth diameter, and a tapered region coupled to the flared end of the first portion and extending away from the flared end of the first portion. The tapered region may have a flared end with a fifth diameter and a tapered end with a sixth diameter such that the fifth diameter is equal to the first diameter and the sixth diameter is smaller than the fifth diameter. The first conical region of the first portion and the second conical region of the second portion may be aligned so that apexes of the first portion and second portion are contacting one another. The hourglass shaped mandrel assembly may further include a neck region positioned between the apex end of the first portion and the apex end of the second portion such that the neck region is affixed to at least the first portion or the second portion. The first portion and the second portion may be removably coupled at the apex end of the first portion and the apex end of the second portion. The hourglass shaped mandrel may be configured to expand radially.

Problems solved by technology

Heart failure is the physiological state in which cardiac output is insufficient to meet the needs of the body and the lungs.

However, the larger volume of blood also stretches the heart muscle, enlarging the heart chambers, particularly the ventricles.

At a certain amount of stretching, the hearts contractions become weakened, and the heart failure worsens.

In low ejection fraction (EF) heart failure, high pressures in the heart result from the body's attempt to maintain the high pressures needed for adequate peripheral perfusion.

However, the heart weakens as a result of the high pressures, aggravating the disorder.

Pressure in the left atrium may exceed 25 mmHg, at which stage, fluids from the blood flowing through the pulmonary circulatory system flow out of the interstitial spaces and into the alveoli, causing pulmonary edema and lung congestion.

This stiffness may impede blood from filling the heart, and produce backup into the lungs, which may result in pulmonary venous hypertension and lung edema.

However, pharmacological approaches are not always successful, as some people may be resistant or experience significant side effects

Such mechanical devices enable propulsion of significant volumes of blood (liters / min), but are limited by a need for a power supply, relatively large pumps, and the risk of hemolysis, thrombus formation, and infection.

However these approaches are highly invasive and have the general risks associated with highly invasive surgical procedures.

However, Dobak states that a valved design may not be optimal due to a risk of blood stasis and thrombus formation on the valve, and that valves can also damage blood components due to turbulent flow effects.

Dobak does not provide any specific guidance on how to avoid such problems.

While Banas describes a method for encapsulating a cylindrical stent, the method in Banas does not describe encapsulation of an hourglass shaped stent intended for treatment of CHF.

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