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

Intervention / Treatment

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

  • United States
    • 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)
Other: Pulmonary Index of Microcirculatory Resistance
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:
  • PIMR
PAH
10 patients with PAH
Other: Right Ventricle Index of Microcirculatory Resistance
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:
  • RV-IMR
Other: Pulmonary Index of Microcirculatory Resistance
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:
  • PIMR
Other: Pulmonary artery OCT
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
Other: Right Ventricle Index of Microcirculatory Resistance
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:
  • RV-IMR
Other: Pulmonary Index of Microcirculatory Resistance
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:
  • PIMR
Other: Pulmonary artery OCT
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.

Sponsor

University of California, Los Angeles

Collaborators

Abbott

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

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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