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Completed

NCT Number: NCT05843461

PIMR and Pulmonary Vascular Disease

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.

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Key information

Conditions

Pulmonary Hypertension Cardiovascular Diseases Hypertension Hypertension, Pulmonary Lung Diseases Pulmonary Arterial Hypertension Respiratory Tract Diseases Vascular Diseases

Age range

18 year and older

Sex eligibility

All sexes

Study type

Observational

Primary location

Ronald Reagan UCLA Medical Center

Los Angeles, California, 90095, United States

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

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)

Treatment and study plan

Pulmonary Index of Microcirculatory Resistance

Other

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

Right Ventricle Index of Microcirculatory Resistance

Other

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

Pulmonary artery OCT

Other

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.

Primary outcomes

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. OCT-derived wall-area ratio

    Time frame: Baseline

Sponsors and collaborators

Lead sponsor

University of California, Los Angeles

Other

Collaborators

  • Abbott

Registry information

Official study title

The Pulmonary Index of Microcirculatory Resistance: a Novel Hemodynamic Index for Invasively Assessing the Pulmonary Vasculature

Important dates

Study start
2023
Primary completion
2024
Study completion
2024
First posted
May 6, 2023
Registry last updated
Dec 5, 2024

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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