PV Loop and Pulmonary Hypertension

Study Overview
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Brief Summary
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The right ventricular (RV) systolic function is a key determinant of outcome in patients with pulmonary hypertension and elevated pulmonary vascular resistance. As the pulmonary artery pressure and vascular resistance increase (i.e. RV afterload) in these patients, so does the right ventricular contractility in an attempt to maintain cardiac output. This is response of a ventricle to its afterload is termed ventriculo-arterial (VA) coupling. However, there is a limit to this increase in contractility after which VA uncoupling occurs ultimately leading to decrease cardiac output and right ventricular failure. The accepted gold standard for measurement of VA coupling is the ratio of the end systolic ventricular elastance (Ees) to the end systolic arterial elastance (Ea) measured invasively via high fidelity conductance catheters during cardiac catheterization. In this study, the aim is to devise a non-invasive scoring system that can identify VA uncoupling in patients with elevated pulmonary vascular resistance using echocardiography, cardiac MRI, cardiopulmonary exercise testing and brain natriuretic peptide levels. The hypothesis is that a group of morphologic and functional variables obtained noninvasively can differentiate an RV with VA coupling from that with VA uncoupling.

Official Title
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Non-Invasive Evaluation of Right Ventricular - Pulmonary Arterial Coupling in Children With Elevated Pulmonary Vascular Resistance

Conditions
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Pulmonary Vascular Resistance Abnormality

Intervention / Treatment
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* Procedure: Measuring VA Coupling


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Children 1-21 years of age Patients referred for cardiac catheterization for hemodynamic evaluation due to concern for pulmonary hypertension Structurally normal heart Exclusion Criteria: Pulmonary hypertension secondary to pulmonary venous hypertension defined as pulmonary capillary wedge pressure of more than or equal to 15mmHg Pulmonary hypertension secondary to mixed pulmonary arterial and venous hypertension Patient will be excluded from performing an MRI if they have: claustrophobia, metal implants or allergy to contrast Patients will be excluded from performing a cardiopulmonary exercise test (CPET) if they are: 1) less than 8 years or 2) unable to follow instructions to run on a treadmill.

Ages Eligible for Study
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Minimum Age: 1 Year
Maximum Age: 21 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Observational Group<br>Subjects will undergo clinically indicated investigations and tests. The research part of the study is measuring the VA coupling using high fidelity catheters. That is expected to increase the duration of the cardiac catheterization for 30 minutes. | Procedure: Measuring VA Coupling<br>* Subjects will undergo clinically indicated investigations and tests. The research part of the study is measuring the VA coupling using high fidelity catheters. That is expected to increase the duration of the cardiac catheterization for 30 minutes.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Identify echocardiographic measurements of right ventricular systolic function and pulmonary blood flow and their cutoff values contemporaneous that can identify VA uncoupling | Yes/No result: Can echocardiographic measurements allow non-invasive identification of VA uncoupling (defined as Ees/Ea <0.805). Three ratios: tricuspid annular plane systolic excursion to the pulmonary artery acceleration time, right ventricular free wall strain to the pulmonary artery acceleration time and, right ventricular fractional area change to the pulmonary artery acceleration time. | within one week of measurement of ventriculo-arterial coupling ratio during cardiac catheterization | 
| Identify cMRI measurements of right ventricular systolic function and pulmonary blood flow and their cutoff values contemporaneous that can identify VA uncoupling. | Yes/No result: Can cMRI measurements allow non-invasive identification of VA uncoupling (defined as Ees/Ea <0.805). Two ratios: right ventricular ejection fraction to right ventricular end systolic volume and right ventricular ejection fraction to pulmonary artery acceleration time (by echocardiography). | within one week of measurement of ventriculo-arterial coupling ratio during cardiac catheterization | 
| Identify 6-minute walk distance cutoff that can identify VA uncoupling | Yes/No: Can 6-minute walk distance identify VA uncoupling (defined as Ees/Es<0.805) | within one week of measurement of ventriculo-arterial coupling ratio during cardiac catheterization | 
| Identify brain natriuretic peptide cutoff value that can identify VA uncoupling | Yes/No: Can brain natriuretic peptide identify VA uncoupling (defined as Ees/Es<0.805) | within one week of measurement of ventriculo-arterial coupling ratio during cardiac catheterization | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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pulmonary vascular resistance, pediatric, VA uncoupling