Vital heart research receives funding boost

The Prince Charles Hospital’s (TPCH) Critical Care Research Group (CCRG) and Heart Lung Institute (HLI) will forge ahead with vital cardiac research following the receipt of two prestigious national grants awarded by the National Heart Foundation late last month.

The grants, which total just under $200,000, investigate vital issues relating to neurological injury associated with Transcatheter Aortic Valve Implantation (TAVI).

TAVI is a novel procedure where catheters and wires are used to deliver a prosthetic valve to the heart to function in place of the stenosed aortic valves and thus avoiding heart bypass, open heart surgery and a prolonged recovery in hospital. Most patients are home feeling well within three to four days.

Chief investigator, Dr Jonathon Fanning said that although TAVI has substantially expanded the therapeutic options available to high-risk and inoperable patients suffering from severe aortic stenosis, it is associated with a high incidence of neurological injury, including strokes.

“Thankfully, clinically apparent stroke is seen in less than 5 per cent of TAVI patients. However, it appears that subclinical stroke, that is, stroke without physical symptoms, occurs in over 50 per cent. These subclinical strokes represent cerebrovascular injury and are therefore a useful surrogate marker for clinically apparent stroke. They may also have clinical significance in their own right with some studies showing correlation with rapid cognitive decline, psychiatric illness, subsequent clinically apparent stroke and other adverse health outcomes.”

“In both studies we will use magnetic resonance imaging of the patient’s brain in conjunction with serial clinical assessments to determine the occurrence of new stroke, as well as changes in cognition.

The first study, titled SANITY aims to characterize the incidence of neurological injury and identify the patient and procedural risk factors for their occurrence.

“By scanning patients’ brains before and after the procedure we are able to detect new subclinical strokes. In conjunction with our rigorous patient and procedure profiling it is hoped we will be able to identify risk factors for neurological injury. We can then use this information to modify the procedure and patient selection processes so as to reduce the occurrence of neurological injury and better inform patients of their risk.”

The second grant will support a research study that will test novel strategies that could potentially prevent the occurrence of this devastating neurological injury.

This study, titled Neuro-PROTECT will assess the feasibility of remote ischemic preconditioning and induced hypothermia, strategies never tested in an interventional cardiology setting before.

Remote ischemic preconditioning is a protective phenomenon whereby an ischemic insult to one part of the body can reduce tissue injury on subsequent ischemic insults to other organs. For example, a blood pressure cuff on an arm or leg can be used to safely cut off the blood flow to that limb for short periods. This is thought to trigger changes that may protect the heart and the brain during the subsequent ischaemic insult that occurs during the TAVI procedure.

Dr Fanning, who is leading the studies through the CCRG as part of his PhD said: “This process has shown huge promise in cell and animal studies, but translation from the laboratory to clinical practice remains a largely unmet medical need.

A second strategy, induced hypothermia, will also be trialled. It is established that reduction in body temperature reduces the metabolic requirement of the brain and therefore, the oxygen and nutrient and blood requirements of the brain. This reduced demand for blood may allow the brain to cope better when there is reduced supply, as can occur during surgeries.

“While this technique has been used in cardiac arrest and cardiac surgical settings, to our knowledge it has not been applied to an interventional cardiology setting.

“By applying these two strategies to patients undergoing TAVI, we hope to be able to show there are some active preventative measures that can be taken to reduce the level of stroke in patients perioperatively. If successful, the application of these strategies may be broad and extend into many other interventions and surgeries.

“The goal of our research is to make TAVI safer for patients and ultimately improve the overall outcomes of patients undergoing transaortic valve implantation.”

Professor Fraser said: “The success of these studies highlights the benefits of a silo-free approach to research.

“The idea driven from the CCRG can only work through the clinical excellence demonstrated by our radiology and HLI teams.

“This research will then translate to improved outcomes for our patients – through the collaboration of many different clinical and research teams all pursuing the same goal.”