PIMR and Pulmonary Vascular Disease
December 3, 2024 updated by: Rushi V. Parikh, University of California, Los Angeles
The Pulmonary Index of Microcirculatory Resistance: a Novel Hemodynamic Index for Invasively Assessing the Pulmonary Vasculature
The findings from this innovative, first-in-man, prospective pilot study will elucidate the role of PIMR and RV-IMR in pre-capillary PH.
The study cohort will consist of patients with pulmonary pressures ranging from normal (advanced lung disease patients undergoing lung transplant evaluation) to severe PH (PAH and CTEPH patients), and thus will allow for identification of a PIMR cutoff.
Participants will include: 1) advanced lung disease patients undergoing bilateral heart catheterization as part of their pre-lung transplant work-up, and 2) newly referred patients to PAH and CTEPH clinics undergoing bilateral heart catheterization as part of standard of care work-up.
All participants will undergo PIMR testing, and those with pre-capillary PH will also undergo pulmonary OCT and measurement of RV-IMR.
The study seeks to define the relationship between PIMR and PH and to establish the PIMR threshold that identifies pulmonary microvascular dysfunction as well as to evaluate the association of PIMR and pulmonary vascular remodeling on OCT in patients with pre-capillary PH.
In addition, the study will assess the relationship between RV-IMR and RV pressure overload among patients with pre-capillary PH.
Study Overview
Status
Completed
Conditions
Study Type
Observational
Enrollment (Actual)
30
Contacts and Locations
This section provides the contact details for those conducting the study, and information on where this study is being conducted.
Study Locations
-
-
California
-
Los Angeles, California, United States, 90095
- Ronald Reagan UCLA Medical Center
-
-
Participation Criteria
Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.
Eligibility Criteria
Ages Eligible for Study
- Adult
- Older Adult
Accepts Healthy Volunteers
No
Sampling Method
Non-Probability Sample
Study Population
Patients scheduled to undergo standard-of-care right and left heart catheterization either for evaluation of suspected or known pulmonary hypertension (PAH or CTEPH) or for lung transplant evaluation in the setting of advanced lung disease
Description
Inclusion Criteria:
- ≥18 years old
- Able to provide informed written consent.
- Patients with 1) advanced lung disease requiring standard-of-care bilateral heart catheterization as part of lung transplant evaluation in whom mPAP < 20 mmHg on RHC, or 2) PAH/CTEPH (i.e. pre-capillary PH) undergoing standard-of-care bilateral heart catheterization as part of their work-up/treatment
Exclusion Criteria:
- Contraindicated to undergo fluoroscopy and/or coronary angiography (e.g. pregnancy)
- Chronic kidney disease (serum creatinine ≥ 2.0 mg/dL)
Study Plan
This section provides details of the study plan, including how the study is designed and what the study is measuring.
How is the study designed?
Design Details
Cohorts and Interventions
Group / Cohort |
Intervention / Treatment |
|---|---|
|
Controls
10 patients without pulmonary hypertension (mean PA pressure less than 20 mmHg on RHC)
|
PIMR measurement involves placing a coronary pressure wire in the pulmonary arteries and making pressure/time measurements during maximal flow down the artery.
PIMR of the right and left pulmonary arteries will be obtained.
Other Names:
|
|
PAH
10 patients with PAH
|
RV-IMR measurement involves placing a coronary pressure wire in the acute marginal branch of the right coronary artery and making pressure/time measurements during maximal flow down the artery.
Other Names:
PIMR measurement involves placing a coronary pressure wire in the pulmonary arteries and making pressure/time measurements during maximal flow down the artery.
PIMR of the right and left pulmonary arteries will be obtained.
Other Names:
OCT of the pulmonary artery involves advancing an OCT catheter over the pressure wire to image the pulmonary artery.
OCT of the right and left pulmonary arteries will be performed.
|
|
CTEPH
10 patients with CTEPH
|
RV-IMR measurement involves placing a coronary pressure wire in the acute marginal branch of the right coronary artery and making pressure/time measurements during maximal flow down the artery.
Other Names:
PIMR measurement involves placing a coronary pressure wire in the pulmonary arteries and making pressure/time measurements during maximal flow down the artery.
PIMR of the right and left pulmonary arteries will be obtained.
Other Names:
OCT of the pulmonary artery involves advancing an OCT catheter over the pressure wire to image the pulmonary artery.
OCT of the right and left pulmonary arteries will be performed.
|
What is the study measuring?
Primary Outcome Measures
Outcome Measure |
Measure Description |
Time Frame |
|---|---|---|
|
Pulmonary Index of Microcirculatory Resistance (PIMR)
Time Frame: Baseline
|
PressureWire advanced to distal third of segmental pulmonary artery (PA) for measurement of pulmonary hemodynamics.
The derivation of IMR involves the application of Ohm's law (V=IR) to the coronary microcirculatory circuit, where the relationship between resistance (R) = IMR, voltage (V) = pressure (P), and current (I) = flow (Q) can be expressed as follows: IMR = ∆P/Q.
∆P = the change in pressure across the microvasculature (mean distal coronary artery pressure [Pd] - coronary venous pressure (Pv); Pv is typically disregarded because it is negligible relative to Pd.
Based on the principles of thermodilution, flow is inversely proportion to mean transit time (Q ~ 1/Tmn).
Lastly, the minimal achievable resistance occurs during maximal hyperemic flow when all available microvessels have theoretically been recruited.
Hence, the calculation of IMR simplifies to the following formula: IMR = Pd (pulmonary artery) x TmnHyp.
|
Baseline
|
|
Right Ventricle Index of Microcirculatory Resistance (RV-IMR)
Time Frame: Baseline
|
PressureWire advanced to distal third of acute marginal branch of the right coronary artery (RCA) for measurement of pulmonary hemodynamics.
The derivation of IMR involves the application of Ohm's law (V=IR) to the coronary microcirculatory circuit, where the relationship between resistance (R) = IMR, voltage (V) = pressure (P), and current (I) = flow (Q) can be expressed as follows: IMR = ∆P/Q.
∆P = the change in pressure across the microvasculature (mean distal coronary artery pressure [Pd] - coronary venous pressure (Pv); Pv is typically disregarded because it is negligible relative to Pd.
Based on the principles of thermodilution, flow is inversely proportion to mean transit time (Q ~ 1/Tmn).
Lastly, the minimal achievable resistance occurs during maximal hyperemic flow when all available microvessels have theoretically been recruited.
Hence, the calculation of IMR simplifies to the following formula: IMR = Pd (RCA marginal branch) x TmnHyp.
|
Baseline
|
|
OCT-derived pulmonary artery wall thickness
Time Frame: Baseline
|
A Dragonfly Optis OCT catheter (Abbott) will be advanced over the PressureWireX to the distal left lower lobe segmental pulmonary artery (luminal diameter < 5 mm and minimal length of 50 mm).
OCT images of the pulmonary artery will be recorded via automatic pullback and analyzed offline in a blinded manner.
|
Baseline
|
|
OCT-derived thickness-diameter ratio
Time Frame: Baseline
|
A Dragonfly Optis OCT catheter (Abbott) will be advanced over the PressureWireX to the distal left lower lobe segmental pulmonary artery (luminal diameter < 5 mm and minimal length of 50 mm).
OCT images of the pulmonary artery will be recorded via automatic pullback and analyzed offline in a blinded manner.
|
Baseline
|
|
OCT-derived wall-area ratio
Time Frame: Baseline
|
Baseline
|
Collaborators and Investigators
This is where you will find people and organizations involved with this study.
Collaborators
Investigators
- Principal Investigator: Rushi Parikh, MD, University of California, Los Angeles
Study record dates
These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.
Study Major Dates
Study Start (Actual)
January 10, 2023
Primary Completion (Actual)
July 31, 2024
Study Completion (Actual)
July 31, 2024
Study Registration Dates
First Submitted
April 24, 2023
First Submitted That Met QC Criteria
April 24, 2023
First Posted (Actual)
May 6, 2023
Study Record Updates
Last Update Posted (Estimated)
December 5, 2024
Last Update Submitted That Met QC Criteria
December 3, 2024
Last Verified
December 1, 2024
More Information
Terms related to this study
Keywords
Additional Relevant MeSH Terms
Other Study ID Numbers
- IRB#22-001643
Plan for Individual participant data (IPD)
Plan to Share Individual Participant Data (IPD)?
NO
Drug and device information, study documents
Studies a U.S. FDA-regulated drug product
No
Studies a U.S. FDA-regulated device product
No
product manufactured in and exported from the U.S.
No
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