Imaging for guidance of interventions for cardiovascular disease
Interventional guidance provides new possibilities to further help in the treatment of patients with cardiac disease.
Our lab is part of the Imaging Research Centre for Cardiac Intervention (IRCCI). This organization brings together basic scientists and clinical researchers to improve the management of cardiac disease. Advances in X-ray, ultrasound, optical and MR-imaging and catheter-based sensors will be integrated to facilitate the following:
- Novel revascularization methods
- Gene and stem cell therapies
- Electrophysiological interventions
- Minimally invasive surgery
We also work to provide the early feedback on success critical to rapid outcome evaluation.
Our contribution to the collaboration will be in the areas of imaging intervention and electrophysiology intervention.
Imaging intervention
Revascularization
Chronic total occlusion (CTO ) of blood vessels typically requires treatment via bypass surgery. There has been substantial recent success in opening and keeping open narrowed vessels less invasively with angioplasty and drug-eluting stents. This motivates us to explore similar strategies for CTO.
To predict success in crossing and to provide roadmaps for intravascular interventions, the first step is to characterize the tissue properties in CTOs. CTOs will be created in the femoral artery using animal models and assessed over time using various imaging modalities that include magnetic resonance angiography, high frequency ultrasound, computer tomography, optical computer tomography and X-ray.
We will use this information to guide characterization of CTOs in the patient population.
Characterization of the occlusion will involve:
- Using gadolium (Gd), a magnetic resonance contrast agent, to determine whether Gd can be seen up- and downstream of the occlusion, which may indicate the presence of channels through the occlusion; this may then indicate the possibility of using a device to open the occlusion instead of by-pass surgery as treatment
- Measuring the oxygen level of blood or tissue up- and downstream of the occlusion using the relationship between steady-state free precession and oxygen (PDF, 40 KB)
- Characterising wall motion, perfusion
- Measuring flow (FIA)
- Quantitative T1 and T2 imaging
Regeneration
Excitement surrounds the use of stem cells, since these cells can potentially become functional cells of any given tissue. Stem cells implanted to a damaged area of the heart may be able to fully replace the damaged area in all the necessary aspects.
This project requires the ability to:
- Visualize the catheter needed to deliver the stem cells (Kevan Anderson)
- Image (in real-time) the progress of the catheter movement and maintain knowledge of its orientation (Dingrong Yi)
- Study the function in the neighbourhood of the cells
- Characterize the general functions of the tissue (Jay Detsky) such as wall motion recovery, perfusion, viability, proliferation and differentiation (Yuesong Yang)
This study is funded by a grant from the Heart and Stroke Foundation held by Alexander Dick.
Electrophysiology intervention
Arrhythmias associated with heart attacks can lead to open-heart surgery, which involves slicing up the heart muscle to eliminate the irregular heart contraction. To reduce the severity of intervention, we are studying muscle ablation via radio frequency (RF) heating.
This study involves the ability to observe the delivery of the RF heating to the desire place and imaging the ablation.
We need an electromechanical heart model to further understand the behaviour of the heart under normal and arrhythmic conditions and to try to predict the source of the arrhythmia (Mihaela Pop).
We will be collaborating with other groups working on more specific aspects of the heart model:
- INRIA
- University of Toronto - Michael Joy: electric current density imaging
- National Institutes of Health - John Hopkins: mechanical heart model