A team of specialists from King's College London, St Thomas' Hospital, and Siemens Healthineers have recently published details of a novel approach to lead placement during image guided cardiac resynchronization therapy (also known as CRT).
What is cardiac resynchronization therapy?
Cardiac resynchronization therapy is a common procedure offered to patients who suffer from heart failure for which drug management alone is not effective. The condition prevents the heart from beating normally due to uncoordinated electrical activity. This means the organ struggles to circulate blood and oxygen around the body, resulting in patients straining with simple, everyday tasks.
The aim of the therapy is to resynchronize the contractions of the heart ventricles by implanting a device in the patient which can deliver electrical signals to the heart muscle. In order to do so, three pacing leads must be placed into the right atrium, the right ventricle, and the left ventricle of the patient's heart.
The lead placement in the left ventricle specifically has a critical influence on the procedure, and sub-optimal placement can cause poor outcomes in around 40% of cases. However, the optimal location is highly patient specific and can be affected by both anatomy and disease factors such as the presence of scar tissue.
How can software be used for patient benefit?
The researchers have developed an integrated guidance system which fuses pre-operative imaging data in real time during the insertion of the leads, typically performed using a catheter under X-Ray fluoroscopy guidance
The software creates a patient specific left ventricle model using MRI scan data which takes into account critical metrics such as the presence of scar tissue and the latest point of mechanical activity. Automatic segmentation of the scar tissue has also been incorporated into the software through machine learning techniques.
This allows surgeons to quickly and easily calculate the optimal position for the lead placement and use this as guidance during therapy by fusing the information with the fluoroscopic images.
The system has been developed and tested using an XMR facility, a suite which combines both an MRI scanner and a catheter lab in adjoining rooms. Patients are scanned in the MRI directly before their procedure and the software is able to process the pre-operative data by the time it takes to transfer the patient to the catheter lab, demonstrating the significant time-saving possibilities of this system.
Clinical lead, Prof Aldo Rinaldi, comments: "CRT results in significant improvement in patient's quality of life and can prolong survival. Unfortunately, approximately one third of patients do not respond to treatment and this is especially the case in patients with scar within their hearts. Using a guidance system which can avoid areas of scarring within the heart has the potential to dramatically increase the benefit of this therapy and improve patient outcomes."
A new image guided system
During this project the researchers were able to demonstrate proof of concept for 20 patients. Whilst exciting, wider scale trials are required to fully demonstrate the feasibility and efficacy of this integrated guidance platform. However, as the system has been designed to fit within the current clinical workflow any further translation of this research should be widely suitable for other teams and treatment centers to use. With cardiovascular disease being a global condition, the potential for creating impact and improving quality of life for those with heart failure is vast.
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