Can Tiny Bubbles Offer an Alternative to Catheters for Assessing Pressures Inside the Heart? Investigating Ultrasound Contrast Agents as Pressure Sensors Against Gold Standard Catheter Pressures in Cardiac Catheterisation Patients.

This study will record ultrasound contrast signals simultaneously with gold standard catheter pressure measurements inside the heart, to enable a direct comparison between the two methods. Complementary ultrasound data will be used to develop a personalised calibration solution to convert the contrast signal in dB to estimated pressure in mmHg. All study procedures will be completed on the same day as the participant's standard of care cardiac catheterisation and no additional study visits will be required.

Inclusion criteria

• Participant is willing and able to give informed consent to participate in the study
• Patients who require a cardiac catheterisation procedure as part of their standard medical care
• Good acoustic windows for echocardiography when lying flat on their back

Exclusion criteria

• Known previous allergy to SonoVue, used in ultrasound contrast scans
• Known allergy to any of the components of SonoVue microbubbles, for example, sulphur hexafluoride or polyethylene glycol (PEG), also known as macrogol, which is in bowel preparations used during colonoscopy and certain laxatives
• A hole in their heart that lets blood flow from the right side to the left, skipping the lungs
• Very high blood pressure in the arteries of the lungs (severe pulmonary hypertension)
• Uncontrolled high blood pressure (hypertension)
• Adult respiratory distress syndrome (ARDS; where severe lung inflammation prevents enough oxygen from reaching the body)
• Current use of the medicine dobutamine (used to treat heart failure), or have been advised not to take dobutamine
• Moderate to severe heart valve disease that could affect the catheter measurements
• Recent acute coronary syndrome or unstable ischaemic cardiac disease, where blood flow to the heart muscle is reduced
• Pregnant or may be pregnant
• Participation in a clinical trial of a medicine within the past four months, to avoid any possible interactions with SonoVue
• Participating in other research that would prolong their cardiac catheterisation procedure, to ensure that the overall process does not become too tiring or burdensome