The study will compare standard ultrasound images to high frame rate ultrasound images in patients with heart disease or with a low risk of heart disease to see if a higher frame rate of ultrasound adds to the information obtained from standard ultrasound.

Following informed consent, patients recruited for the study will have an IV cannula inserted and will undergo imaging using 2 ultrasound systems. Standard clinical system (Philips IE33) will be used for 2D and CE imaging, followed by imaging using the Verasonics VantageTM research system (Verasonics Inc., Redmond, WA), using both conventional 2D and HFR modes.

Baseline unenhanced 2D and Doppler images would initially be acquired using Philips IE33 system and Verasonics VatangeTM unenhanced conventional 2D and HFR mode .

Ultrasound contrast agent (Sonovue) will be then injected via the intravenous (iv) cannula and 3 sets rest contrast images will be acquired - using the Phillips IE33, Verasonics and Verasonics VantageTM platform (conventional CE and HFR CE). Both systems will be optimised separately on each patient before and during infusion of contrast agent. When the optimal imaging and destruction parameters are set, there are not modified along the acquisition.

This is followed by dipyridamole infusion and the scans being repeated during stress - 3 sets contrast images will be acquired - using the Philips IE33 and Verasonics VantageTM platform (conventional CE and HFR CE).

Inclusion criteria Either

• Ability to give informed consent
• age ≥18years and
• confirmed inducible wall motion / perfusion abnormality on previous stress echocardiogram
• known coronary artery disease - defined by presence of flow-limiting coronary stenosis(>70% diameter stenosis) on coronary angiography.

OR

• patient who has been assessed as at low risk of having coronary heart disease

Exclusion Criteria:

• Inability to undertake pharmacological stress, ie previously known intolerance to dipyridamole;
• Moderate or Severe aortic or mitral regurgitation or severe mitral stenosis;
• Significant pulmonary disease like severe COPD or pulmonary fibrosis;
• Atrial fibrillation;
• Inability to provide informed consent;
• Pregnancy and lactation;
• Known allergy to Sonovue
• Patients with second and third degree heart block, unless they have a pacemaker fitted
• Systolic BP < 90
• Known Myasthenia Gravis
• Bronchial asthma

25 patients will be recruited over 12 months. 5 of these patients will be at low high of having coronary artery disease and 20 at high risk of coronary artery disease. patients will be recruited from those referred for clinical stress stress echocardiography.

Individual data will not be shared