TECHNICAL FIELD

The present invention relates to implantable Flow Streamliner and more particularly related to an implantable Flow Streamliner for passive control of blood flow in desired direction with reduced energy loss in a patient. The present application is based on, and claims priority from an Indian Application Number 3091/MUM/2015 filed on 14 Aug. 2015 the disclosure of which is hereby incorporated by reference.

BACKGROUND OF INVENTION

In most cases of congenital heart disease, it is essential to improve pulmonary circulation. It is particularly desirable to maintain normal blood circulation to the lungs of the patient.

FIG. 1is a schematic depicting a natural circulation of blood in a human body. Deoxygenated blood from the entire human body is received in the Right Atrium (RA) of a heart and supplied to the Right Ventricle (RV). The RV further pumps the blood into the lungs for oxygenation from where it is received in the Left Atrium (LA) of the heart. The oxygenated blood collected in the LA is then received in the Left Ventricle (LV) which further pumps it to the body thus completing the close circuit.

FIG. 2is a schematic representing the blood circulation in the human body having congenital heart defect (CHD) with a single ventricle. In case of the congenital heart defect, the RV is malformed and both atria are interconnected due to a hole. As a result, the LV alone has to pump the mixture of the oxygenated blood and the deoxygenated blood to the lungs and to the body both. Further, the blood from the lungs and the body returns to the LA and the RA respectively, to complete the circuit in two parallel close loops.

In normal cardiovascular circulation the blood flows in a single close loop. RV and LV are anatomically separated by intervening partition, called as inter-ventricular septum. In this close loop of cardiovascular flow, the ventricles are separated by pulmonary and systemic vascular tree. When one of the ventricles is underdeveloped, the functional ventricle has to pump the blood in both systemic and pulmonary vasculature. This results in two parallel loops.

The probability of children born with CHD having only one effective ventricle is about 2 per 1000 births. In children with such birth defect, the single ventricle has to pump the blood simultaneously to the body as well as to the lungs. In these cases, the single ventricle is pumping into the systemic (body) and pulmonary (lungs) vascular network. This parallel circulation (across pulmonary and systemic vascular network) causes cyanosis which is a result of mixing of the oxygenated and the deoxygenated blood in the single ventricle. It also creates ventricular volume overload. Due to these reasons, the children with one effective ventricle need to be treated to increase the life expectancy. For the palliation of this kind of severe congenital heart problem, a surgical procedure is performed, called as Fontan surgery.

The Fontan surgery procedure involves correcting the congenital heart defect, wherein the inter-atrial septal hole is closed and the right atrium is connected directly to the pulmonary artery bypassing the right ventricle completely from the blood circulation circuit. Thus, the Fontan surgery prevents mixing of the oxygenated blood with the deoxygenated blood and also renders the circulation circuit in a single close loop. However, in the absence of the RV the blood supply from the body to the lungs becomes a passive process and hence possesses less kinetic energy. The blood circulation in the human body after a Fontan surgery is schematically shown inFIG. 3.

Sectional anatomies of a normal human heart and that of suffering from CHD are shown inFIGS. 4aand 4b, respectively. As shown, septum divides the heart vertically into left heart and right heart and each of them is further horizontally divided into atrium and ventricle with a non-return valve between them. Thus a heart has four chambers—Left Atrium (LA), Left Ventricle (LV), Right Atrium (RA) and Right Ventricle (RV). Deoxygenated blood from upper body (head and arms) and lower body (torso and legs) is carried to heart through Superior Vena Cava (SVC) and Inferior Vena Cava (IVC), and is collected in Right Atrium. From RA this blood is supplied through Tricuspid Valve (TV) to RV which pumps it through Pulmonary Valve (PV) to Left Pulmonary Artery (LPA) and Right Pulmonary Artery (RPA) leading to left and right lungs. Oxygenated blood from lungs returns to heart through Pulmonary Veins and gets collected in LA which pushes it through Mitral Valve (MV) into LV. Contraction of LV pumps oxygenated blood through Aortic Valve (AV) to highly curved Aorta whose branches supply it to the upper body and the lower body, thus completing the circuit of blood circulation.FIG. 4bshows a typical congenital heart defect wherein the RV is malformed and inter-atrial septum between RA and LA has a hole allowing mixing of oxygenated blood with deoxygenated blood. In this situation LV alone pumps the mixed blood to the body and to the lungs as well thereby causing continual deterioration of child's health, warranting an early Fontan surgery.

The surgery termed as “Total Cavo-Pulmonary Connection” (TCPC) is currently the most promising modification of a Fontan surgical repair (i.e., Fontan surgery) for single ventricle congenital heart disease. The TCPC involves a surgical connection of the SVC and the IVC directly to the RPA, bypassing the right heart to create flow in series. The SVC and the IVC with a prosthetic tubular extension are always connected to the RPA owing to relatively shorter distance resulting in elongation of the LPA from the junction. Further, the pulmonary artery is severed along the dotted line (shown inFIG. 4b) from the T-joint between the RPA and the LPA, and both the open ends are then sutured to close. In the univentricular system, the ventricle experiences a workload which may be reduced by optimizing the cavae-to-pulmonary anastomosis. This palliative surgical procedure leads to a separation between the oxygenated and the deoxygenated blood, which is critical for effective oxygen transport to the human body. As a result of this modified blood circulation, the single ventricle experiences an increased workload, pumping the blood to both the systemic circulation and to the lungs.

The TCPC surgery is the most practiced Fontan operation which has two variants—Intracardiac TCPC and Extra cardiac TCPC as shown inFIGS. 5aand 5b, respectively. In TCPC surgery, a surgeon disconnects the SVC and the IVC from the RA of heart and joins them directly to the RPA to direct returning blood from the body to lungs. While the Intracardiac TCPC involves construction of a composite intra-atrial tunnel with the use of the posterior wall of the RA, the extracardiac TCPC involves extension of IVC using a prosthetic tube exterior to RA. Both the TCPC variants present a configuration in a simple form of a cross connection. As a result of this TCPC surgery, the blood streams flowing in opposite directions through the SVC and the IVC collide head on with each other and lose momentum thereby causing the loss of kinetic energy. In addition, an undesirable turbulence and unsteadiness are also created due to the collision between these blood streams as schematically represented inFIG. 6.

There exists a mechanism to minimize the impact of the collision of the SVC and the IVC blood streams, by providing an offset between the SVC and IVC axes as schematically shown inFIG. 7. As a result of the offset provided, a vortex is naturally formed due to shear between the opposite blood streams at the junction which facilitates smooth flow of blood to the lungs and a little energy is absorbed from the blood streams to sustain the rotation of the vortex. Further, due to the sharp corners at the joints of the SVC and the IVC with each of the pulmonary artery (i.e., RPA and LPA) cause blood flow separation which becomes additional source of energy loss. The overall energy loss due to vortex formation and blood flow separation is still less compared to the head on collision of the blood streams.

However, this surgical offset leads to lung developmental problems caused due to unequal IVC blood flow distribution. For example, depending on the extent of the offset, the blood streams choose their paths and create a bias for the IVC blood towards one of the lungs, thereby depriving the other lung of nutritive secretion that is provided by the liver to the IVC blood.

SUMMARY

The principal object of the embodiments herein is to provide an implantable Flow Streamliner for passively regulating blood streams in a subject for a TCPC surgery and also in a subject for corrective procedure for improving hemodynamics in old case of TCPC.

Another object of the embodiments herein is to provide the implantable Flow Streamliner for splitting a blood stream from an IVC and a blood stream from an SVC, without a collision between the blood streams.

Another object of the embodiments herein is to provide the implantable Flow Streamliner for distributing the blood stream from the IVC, containing hepatic nutrients, in appropriate proportion to the LPA and the RPA.

Another object of the embodiments herein is to provide the implantable Flow Streamliner for distributing the blood stream from the SVC in appropriate proportion to the LPA and the RPA.

Yet another object of the embodiments herein is to provide the implantable Flow Streamliner for facilitating natural growth of the blood vessels which is essential for the increasing blood supply of patients with their growing age.

Yet another object of the embodiments herein is to provide an implantable Flow Streamliner for appropriately guiding the flow of the IVC blood carrying hepatic contents to both the lungs depending on impedance offered by each pulmonary vascular tree.

Yet another object of the embodiments herein is to provide the implantable Flow Streamliner to enable confluence of streams of the SVC and the IVC blood with minimal shear between the streams based on accurate placement of the implantable Flow Streamliner in the pulmonary artery.

Yet another object of the embodiments herein is to provide the implantable Flow Streamliner for corrective procedure in an old case of the TCPC to suppress the vortex formation due to an offset between the SVC and the IVC.

Yet another object of the embodiments herein is to provide the implantable Flow Streamliner to smoothly guide the blood from the IVC carrying hepatic nutrients to both the lungs in an old case of TCPC with any offset between the SVC and the IVC.

Yet another object of the embodiments herein is to provide the implantable Flow Streamliner to smoothly guide the blood from the SVC to both the lungs in an old case of TCPC with any offset between the SVC and the IVC.

Accordingly the embodiments herein provide an implantable Flow Streamliner for passively regulating blood streams in a TCPC subject. The implantable Flow Streamliner is configured to split a blood stream from an IVC and a blood stream from a SVC, and enable their confluence without a collision between the blood streams. Further, the implantable Flow Streamliner is configured to distribute the blood stream from the IVC, containing hepatic nutrients, in proportion to a LPA and a RPA. Further, the implantable Flow Streamliner is configured to distribute the blood stream from the SVC in proportion to the LPA and the RPA.

In an embodiment, the implantable Flow Streamliner is a cardio-vascular Flow Streamliner.

In an embodiment, the blood stream from the IVC, containing the hepatic nutrients, is regulated in proportion to the LPA and the RPA without constraint.

In an embodiment, the blood stream from the SVC is regulated in proportion to the LPA and the RPA without constraint.

In an embodiment, the implantable Flow Streamliner is configured to enable confluence of the blood streams from the SVC and the IVC to the RPA and the LPA.

In an embodiment, the implantable Flow Streamliner is positioned horizontally at about the mid-plane of the junction facing towards the IVC and the SVC, wherein the SVC and the IVC are connected with the RPA facing each other.

In an embodiment, the implantable Flow Streamliner is positioned vertically facing towards the LPA and the RPA, wherein the SVC and the IVC are connected with the RPA facing each other and the implantable Flow Streamliner is connected with the SVC and the IVC along their axes.

In an embodiment, the position of the implantable Flow Streamliner equalizes the velocity of the blood flow from the IVC and the velocity of the blood flow from the SVC at the LPA while leaving the implantable Flow Streamliner.

In an embodiment, the position of the implantable Flow Streamliner equalize the velocity of the blood flow from the IVC and the velocity of the blood flow from the SVC at the RPA while leaving the implantable Flow Streamliner.

In an embodiment, the SVC is connected with the RPA in a flared shaped to enable the blood stream turn smoothly in the RPA and the LPA.

In an embodiment, the IVC is connected with the RPA in a flared shaped to enable the blood stream turn smoothly in the LPA and the RPA.

In an embodiment, the implantable Flow Streamliner is derived from at least a tissue-engineered material, a biocompatible polymers, a biocompatible material, an auto graft, a homograft, and a heterograft.

In an embodiment, the implantable Flow Streamliner is constructed out of a thin sheet at least from soft, hard, rigid, a thin membrane, a flexible material, and a rigid material.

In an embodiment, the implantable Flow Streamliner is constructed as an integral part of an IVC graft.

In an embodiment, the implantable Flow Streamliner is constructed as an integral part of an SVC graft.

In an embodiment, the implantable Flow Streamliner is in at least one of a flat shape, a curved shape in two dimensions (2D) and a curved shape in three dimensions (3D).

In an embodiment, the blood streams from the IVC and from the SVC are enabled to co-flow with a minimal shear at their interface based on the position of the implantable Flow Streamliner at the junction of the SVC, the IVC, the LPA and the RPA.

In an embodiment, the Flow Streamliner has a curvilinear shape adapting to the offset between the SVC and the IVC so as to split the blood streams from the SVC and the IVC into two blood streams and guide them to the RPA and the LPA.

In an embodiment, the implantable Flow Streamliner eliminates bias of the blood streams from the SVC and the IVC, and directs the flow of the blood streams in proportion to the LPA and the RPA.

In an embodiment, the implantable Flow Streamliner corrects irregularity in the TCPC configuration in the form of at least one of dilation and stenosis creating flow abnormalities.

In an embodiment, the implantable Flow Streamliner is implanted by one of a routine surgery, minimally invasive surgery and a catheter-based intervention for correcting the flow abnormalities in old TCPC subjects.

In an embodiment, the implantable Flow Streamliner allows natural growth of the blood vessels which is essential for the increasing blood supply to the lungs of TCPC patients with their growing age.

In an embodiment, the implantable Flow Streamliner is implanted to reduce the energy loss and improves the cardio-vascular hemodynamics in TCPC subjects.

In an embodiment, the implantable Flow Streamliner is an integral component of the graft, simplifies the TCPC surgical procedure.

These and other aspects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating preferred embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.

