Reversibility by Sildenafil of Exercise-Induced Abnormal Right Ventricular Pressure Response in ASD and VSD-Operated Patients
NCT00772135
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- Exercise right ventricular systolic pressure of 45 mm Hg or above.
- Operated for atrial septal defect or ventricular septal defect or minimal defect not operated or minimal residual defect.
- Acute infectious/febrile illness,
- Significant mental or physical disability preventing reliable exercise testing
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Descriptive Information | |||
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Brief Title ICMJE | Reversibility by Sildenafil of Exercise-Induced Abnormal Right Ventricular Pressure Response in ASD and VSD-Operated Patients | ||
Official Title ICMJE | Pulmonary Hypertension in Adolescents and Adults With Congenital Heart Disease | ||
Brief Summary | The purpose of this study is to determine whether oral sildenafil citrate reduces the abnormal right ventricular pressure response during exercise in adolescent and adult patients with specific types of congenital heart defects. | ||
Detailed Description | 13.3 Study design and protocol 13.3.1 Design: double-blind case-control cross-over study 13.3.2 Patients inclusion / exclusion criteria: The study consists of 12-16 patients from the main study (see main protocol) who are selected by following criteria
13.3.3 Examination protocol The patients will be examined similarly twice with at least 12 hours and one night sleep between these activities to ensure drug washout. One hour before each study part, a pharmacy produced capsule (envelope coded and drawn in a random manner from a box) containing either sildenafil citrate 50 mg or placebo will be administered. In this manner each patient will be tested once with placebo use and once with sildenafil use respectively. The participant is taken to a clinical exercise physiology laboratory for testing separated by a night's sleep and at least 12 hours. Monitoring equipment is mounted during the period of drug absorbtion and distribution.
Difffusion capacity monitoring There are two ways of measuring diffusion capacity using SensorMedics V-max analyzing system (Yorba Linda, CA, USA) - intra breath and single breath. Measurements of forced vital capacity (FVC), forced expiratory volume (FEV1), FEV1 ratio (FEV1/FVC), peak expiratory flow (PEF), total lung capacity (TLC or VA), diffusion capacity for carbon monoxide (TLCO), adjusted diffusing capacity (TLCO/VA), residual volume (RV), capillary blood volume (Vc) and membrane conductance (Dm) are included in the analysis and will be performed according to European Respiratory Society standards. Single breath The diffusion capacity is used to estimate the amount of gas travelling from lungs to the bloodstream across the membrane. In the process methane (CH4) is used in the concentration of 0.3 %, 0.3 % carbon monoxide (CO), 21 % oxygen (O2) and nitrogen (N2). In the estimation of TLCO several measurements are included; 1) the area of gas transportation between alveoli and the capillaries (A), 2) the wall thickness (membrane) between the alveoli and the erythrocytes (T), 3) the amount of haemoglobin available (Hb) and 4) the reaction rate of CO too Hb (?) are determinants for the amount of CO that manage to diffuse across to the blood57. In the process CH4 is used as a marker, as it does not diffuse across to the blood but become diluted. CH4 mixes with the residual volume in the lungs, and the degree of dilution is used to calculate alveoli volume. CO diffuses across to the blood in addition to become diluted. By measuring the amount of CO and CH4 in the expiration air compared to the inhaled gas, after a hold of breath in 8-10 seconds, we get an expression for the diffusion capacity in the lungs. Figure 1: The single-breath method for TLCO Intra breath Intra breath reefers to the continuous real-time measurement of carbon monoxide uptake by the pulmonary capillary blood during a single breath maneuver. Intra breath maneuver may be performed during exercise. The calibration procedure samples to set the span points to 0.3 % CO and 0.3 % CH4 (methane). The patient starts with normal breathing and is then instructed to exhale as much as possible - then inhale completely. After total inhalation the patient should exhale at a slow even flow until the computer end the test. The test window shows gas concentration versus time and volume versus time tracing in real time during the maneuver. The flow versus time curve is shown simultaneously. The collection interval used in the calculation of the TLCO is extending from 20 - 80 % of the exhaled volume (marked area in figure 2). Figure 2. The intra breath method for TLCO The patients need to practice this maneuver at rest before using it during exercise. The exhalation time is reduced during exercise, but the patients must try to exhale as slowly as they can in order for the analysis to be correct. Cardiopulmonary monitoring and analysis When analysing changes in vascular resistances during exercise a measurement of pressure is only a part of the hemodynamic picture. According to Ohms law, blood flow measurement is necessary to conclude about the vascular resistances. For this purpose, a non-invasive cardiac stroke volume analyser based on thoracic impedance technique, will be used.(Task Force Monitor, CNS systems, product description enclosed) This equipment is validated for cardiac output monitoring as compared with thermodilution as gold standard. Combined with a beat to beat finger cuff system for measurement of blood pressure, this machine produces core circulatory parameters continuously. Autonomic nervous function (BP variation, HR variation) and baroreflex sensitivity is also analysed. Continuous measurement of peripheral oxygen saturation is registered with Masimo SET pulse oximeters. 13.4 Statistics Responses with and without sildenafil will be compared within same individual. For parameters affected by calibration differences in machinery from test 1 to 2 delta values will be compared. Power analysis: Data from the main study allow estimations of anticipated results and statistical power. If the average of maximal RVSP during exercise in our group is 50 mmHg and sildenafil causes a 20% decrease in average to 40 mmHg (SD 10.0) a sample size of 13 patients leads to statistical power of 81.7% with 5% confidence level (calculation: DSS research 10.7.2008, http://www.dssresearch.com/toolkit/spcalc/power_a2.asp | ||
Study Type ICMJE | Interventional | ||
Study Phase ICMJE | Not Applicable | ||
Study Design ICMJE | Allocation: Randomized Intervention Model: Crossover Assignment Masking: Triple (Participant, Care Provider, Investigator) Primary Purpose: Basic Science | ||
Condition ICMJE | Congenital Heart Disease | ||
Intervention ICMJE | Drug: sildenafil citrate
capsule of 50 mg , 90 minutes before exercise study | ||
Study Arms ICMJE | Not Provided | ||
Publications * | Not Provided | ||
* Includes publications given by the data provider as well as publications identified by ClinicalTrials.gov Identifier (NCT Number) in Medline. | |||
Recruitment Information | |||
Recruitment Status ICMJE | Unknown status | ||
Estimated Enrollment ICMJE | 15 | ||
Original Estimated Enrollment ICMJE | Same as current | ||
Estimated Study Completion Date ICMJE | April 2009 | ||
Estimated Primary Completion Date | February 2009 (Final data collection date for primary outcome measure) | ||
Eligibility Criteria ICMJE | Inclusion Criteria:
Exclusion Criteria:
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Sex/Gender ICMJE |
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Ages ICMJE | 16 Years to 25 Years (Child, Adult) | ||
Accepts Healthy Volunteers ICMJE | No | ||
Contacts ICMJE | Contact information is only displayed when the study is recruiting subjects | ||
Listed Location Countries ICMJE | Norway | ||
Removed Location Countries | |||
Administrative Information | |||
NCT Number ICMJE | NCT00772135 | ||
Other Study ID Numbers ICMJE | RH 2008 HR 2006 / 2 / 0012 TM 2006 / 2 / 0012 | ||
Has Data Monitoring Committee | No | ||
U.S. FDA-regulated Product | Not Provided | ||
IPD Sharing Statement ICMJE | Not Provided | ||
Responsible Party | Steinar Johansen, Foreningen for Hjertesyke Barn | ||
Study Sponsor ICMJE | Oslo University Hospital | ||
Collaborators ICMJE |
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Investigators ICMJE | Not Provided | ||
PRS Account | Oslo University Hospital | ||
Verification Date | October 2008 | ||
ICMJE Data element required by the International Committee of Medical Journal Editors and the World Health Organization ICTRP |