CO2 as a Stress Agent for Perfusion Imaging (CO2 STRESS)
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|ClinicalTrials.gov Identifier: NCT02043535|
Recruitment Status : Active, not recruiting
First Posted : January 23, 2014
Last Update Posted : April 24, 2017
Myocardial perfusion imaging (MPI) is a nuclear scan using a radioisotope to see blood flow to the muscles of the heart when the heart is at rest and when it is under stress. The stress test in MPI can be done using medications, such as adenosine, that dilate coronary arteries and increase blood flow. Similarly, elevated carbon dioxide (CO2) levels in the blood, or hypercapnia, also dilates arteries and increases blood flow. Thornhill Research Inc. has developed the RespirAct ™ Gen4 sequential gas delivery system used to control CO2 levels in the blood. The RespirAct ™ Gen4 can deliver precise amounts of CO2 through a mouthpiece for inhalation to increase CO2 levels in the blood and thereby increasing blood flow like during stress.
The objective of this study is to compare the differences in blood flow through the arteries of the heart during stress with hypercapnia and adenosine MPI. The imaging will be done using positron emission tomography (PET) with the radioisotope, or tracer, called Rubidium (Rb-82). The Rb-82 is given through a pump, or elution system.
The investigators hypothesize that hypercapnia will induce a stress-to-rest increase in myocardial blood flow by a factor of 2 or more in myocardial regions supplied by non-stenotic arteries in normal volunteers and participants with coronary artery disease.
|Condition or disease||Intervention/treatment||Phase|
|Coronary Artery Disease||Device: Delivery of precise levels of carbon dioxide with the RespirAct™ Gen4 sequential gas delivery system Device: Delivery of rubidium radioisotope (Rb-82) using the automated pump/elution system||Not Applicable|
|Study Type :||Interventional (Clinical Trial)|
|Estimated Enrollment :||60 participants|
|Intervention Model:||Single Group Assignment|
|Masking:||None (Open Label)|
|Official Title:||Effects of Controlled Hypercapnic Stimulation on Myocardial Blood Flow Measured With Positron Emission Tomography|
|Study Start Date :||March 2014|
|Estimated Primary Completion Date :||February 2018|
|Estimated Study Completion Date :||February 2018|
Myocardial blood flow quantification
RespirAct ™ Gen4 Sequential gas delivery breathing circuit: delivery of CO2 in increasing levels.
Rubidium Elution System: delivery of Rb-82 through an automated pump system for myocardial PET perfusion imaging.
Adenosine stress myocardial PET perfusion imaging: as a standard for comparison.
Device: Delivery of precise levels of carbon dioxide with the RespirAct™ Gen4 sequential gas delivery system
All participants will undergo a baseline rest Rb-82 positron emission tomography (PET) myocardial perfusion imaging scan (MPI) with low-dose computed tomography. Following this baseline study, serial Rb-82 PET MPI using three target levels of carbon dioxide (CO2) (50 mmHg, 55 mmHg, and 60 mmHg (± 3 mmHg)) as a stress agent will be performed. The 60 mmHg level will be repeated following a minimum 10 minute rest. A rest/stress Rb-82 PET MPI will be performed after return to normal CO2 levels (normocapnea) using adenosine as the stress agent.
Myocardial perfusion stress testing
Other Name: RespirAct™ Gen4Device: Delivery of rubidium radioisotope (Rb-82) using the automated pump/elution system
All participants will undergo a baseline rest Rb-82 positron emission tomography myocardial perfusion imaging scan (PET MPI) with low-dose CT. Following this baseline study, serial Rb-82 PET MPI using three target levels of pulmonary end-tidal carbon dioxide tension (PetCO2) (50 mmHg, 55 mmHg, and 60 mmHg (± 3 mmHg)) as a stress agent will be performed. The 60 mmHg level will be repeated following a minimum 10 minute rest. A second rest Rb-82 PET MPI will be performed after return to normocapnea, followed by a pharmacologic adenosine stress Rb-82 PET MPI.
Other Name: Ruby-Fill™
- Myocardial blood flow differences [ Time Frame: Difference between baseline rest scan blood flow and hypercapnia stress scan myocardial blood flow at 50 mmHg, 55 mmHg, 60 mmHg levels from baseline. Imaging and intervention analysis will be complete in 4 years. ]The myocardial blood flow (MBF) will be quantified with each Rb-82 PET scan done. Polar-maps representing MBF are generated for each rest and stress state using in-house FlowQuant©software. The rest scan will be the baseline. The myocardial blood flow in the four stress scans using hypercapnia as a stress agent will be compared to the rest baseline myocardial blood flow and the adenosine stress scan myocardial blood flow.
- Absolute myocardial blood flow differences between end-tidal CO2 scans [ Time Frame: Difference between baseline and 60 mmHg PetCO2. Imaging and intervention analysis will be complete in 4 years. ]The effect of increasing doses of pulmonary end-tidal carbon dioxide tension (PetCO2) will be measured and quantification of absolute myocardial blood flow using Rb-82 PET will be calculated. Polar-maps representing MBF are generated for each stress state using in-house FlowQuant©software. Five levels will be measured.
- Difference bewteen absolute myocardial blood flow with hypercapnia and with adenosine stress. [ Time Frame: Quantification and comparison of the differences in myocardial blood flow with adenosine stress and increasing levels of CO2 as a stress agent. Imaging and intervention analysis will be complete in 4 years. ]The effects of hypercapnia and adenosine on absolute myocardial blood flow using Rb-82 PET will be compared. Polar-maps representing MBF are generated for each stress state using in-house FlowQuant©software.
To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.
Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT02043535
|University Of Ottawa Heart Institute|
|Ottawa, Ontario, Canada, K1Y 4W7|
|Principal Investigator:||Terrence D Ruddy, MD||Ottawa Heart Institute Research Corporation|