Permanent ventricular assist device for treating heart failure

#The present invention relates generally to a ventricular assist device for treating congestive cardiac failure, and more particularly to a device that can be permanently implanted into the circulatory system of a patient.

#Congestive heart failure (CHF), also called congestive cardiac failure (CCF) or just heart failure, is the pathophysiologic state in which the heart, via an abnormality of cardiac function, fails to pump blood at a rate commensurate with the requirements of the metabolizing tissues. Heart failure may be caused by cardiomyopathy, heart valves damage, coronary heart disease, hypertension or in some cases diabetes. The heart compensates for the pumping insufficiency by dilating the ventricular chambers, thickening the walls (hypertrophy), and accelerating the pulsation rates.

#More than 11 million patients currently suffer from CHF worldwide with a annual increase of about 10% of cases. Approximately 1 million patients present severe CHF conditions, and 1% are admitted in terminal condition. Nowadays, CHF is considered as the fastest-growing clinical cardiac disease entity in the United States, affecting 2% of the population. Nearly 1 million hospital admissions for acute decompensated CHF occur in the United States yearly, almost double the number seen 15 years ago. The rehospitalization rates during the 6 months following discharge are as high as 50%. Nearly 2% of all hospital admissions in the United States are for decompensated CHF, and heart failure is the most frequent cause of hospitalization in patients older than 65 years. The average duration of hospitalization is about 6 days. An estimated $23 billion are spent on inpatient management of CHF every year, and another $40 billion are spent in the outpatient setting on patients with compensated or mildly decompensated heart failure every year. Despite aggressive therapies, hospital admissions for CHF continue to increase, reflecting the prevalence of this malady.

#The above and other characteristics and advantages of the invention will be more readily apparent through the following examples, and with reference to the appended drawings, wherein:

#FIG. 1 schematically shows a longitudinal cross-sectional view of the permanent ventricular device (PVAD) of the invention implanted in a blood vessel;

#FIG. 2 schematically shows a longitudinal cross-sectional view of the rotor (Pcore), attached to a chassis;

#The present invention is a permanent ventricular assist device (PVAD) used for treating congestive heart failure; thereby enabling a patient in need to lead a normal life. The invention achieves this goal by means of a magnetic blood pump which has its blood conveying part, or rotor, physically separated from the stator by the wall of the blood vessel in which it is implanted. The inventors have realized that major open heart surgery, generally used for implementing a magnetic blood pump in the circulatory system, can be wholly avoided if the rotor and the stator are physically separated and are implanted respectively inside and around the blood vessel at the location of interest. Despite the physical separation of the two major elements of the blood pump, the PVAD of the invention is fully functional and can be permanently implanted in the body of the patient without the necessity of cutting or puncturing the wall of the blood vessel to electrically connect the device to a power supply and controller.

#The principal components of the PVAD 9 of the invention are shown schematically in FIG. 1. The device is a magnetic pump, comprising: i) a passive core 2 (Pcore) fixed onto a chassis 3, either by means of a permanent connection or by a releasable connection using for example mechanical clips, and implanted inside a blood vessel 1; ii) a stator 4 surrounding the outside of said blood vessel 1; and iii) an implantable unit comprising a power supply 5 and a controller 7 electrically connected to stator 4 by electrical wires 16 (note that for simplicity only one wire is shown to represent the many wires that make up the electrical circuit).

#Pcore 2 is shown schematically in FIG. 2. The Pcore 2 comprises a cylindrically shaped hollow body 10, which is designed to be implanted in to the blood vessel with its longitudinal axis 19 aligned in the direction of the blood flow. Pcore 2 further comprises a rotor 11, which is a cylinder with an Archimedes screw created on its outer surface, suspended co-axially within the hollow body 10 by means of magnetic bearings (see FIG. 3) situated at each end. The rotor 11 contains a permanent magnet 14 (see FIG. 3) embedded in it or is made of a permanently magnetized material. The permanent magnets of the Pcore are arranged such that their magnetic fields will interact with a synchronized varying magnetic field field created by the stator in such a way that the resulting magnetic force will cause rotor 11 to rotate. As the rotor 11 turns, the Archimedes screw pushes on the blood flowing through the hollow body 10, thereby increasing the blood flow rate.