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Pulmonary Hypertension | Does Oral Sildenafil (Viagra) Decrease Mean Pulmonary Artery Pressure After Cardiac Surgery?

Pulmonary Hypertension research study

What is the primary objective of this study?

Post-operative pulmonary hypertension is a risk factor for right ventricular failure and an increasing cause of morbidity and mortality in patients undergoing high-risk cardiac surgery. Several treatments have been used to treat and reduce post operative pulmonary hypertension. Unfortunately none of these treatments are approved for use in this condition and only one (inhaled nitric oxide) is specific enough to pulmonary hypertension to not cause dangerous low blood pressure in the rest of the body. Sadly, inhaled nitric oxide is difficult and expensive to use, and can cause lung damage. Sildenafil citrate is quite specific to the lung vessels, is easy to administer and does not easily cause low blood pressure in other areas of the body. We hypothesize that oral sildenafil 12.5mg will decrease the baseline (pre-dose) mPAP by at least 20% compared with a placebo.

Who is eligible to participate?

Inclusion Criteria: - 18 years of age or older - Scheduled for or has recently undergone a primary or re-do cardiac surgical procedure including coronary artery bypass graft surgery (CABG), heart valve replacement or repair, ascending aortic replacement or repair or any combinations of these procedures with CPB - No documented allergy to sildenafil citrate - No clinical or laboratory evidence on routine blood work of significant renal disease or failure. (requires dialysis or a creatinine >/= 200umol/L) - No clinical or documented laboratory evidence on routine blood work of hepatic disease or failure. (ALT or AST 5x upper limit of normal (ULN) or jaundice) - The patient if female and of child bearing age is not known to be pregnant. - No documented history of severe chronic respiratory disease defined as an FEV/VC1< 50% predicted. - Not currently enrolled as an active participant in another clinical trial of a medical therapy or device. - No documented stroke or transient ischemic attack within 6 months of study participation - No documented critical carotid artery stenosis (>70%) - No retinitis pigmentosa. - The patient has authorized his/her consent to participate in this trial pre-operatively OR consent to participation is granted on the patient's behalf by a substitute decision maker pre or post operatively. POST-OPERATIVELY - A pulmonary arterial catheter (swan-ganz catheter) is insitu. - The patient has a mPAP measurement of >/= 25mmHg for at least 1 hour. - The patient has a mean arterial pressure (MAP) of >/= 65mmHg. - The patient has a heart rate of greater than 40 and less than 130 beats/minute. - The patient is intubated and mechanically ventilated as per standard ventilation protocol at St. Michael's Hospital. - The patient has not received intravenous nitroglycerin or nitroprusside within 1 hour before treatment with study medication. Exclusion Criteria: POST-OPERATIVELY - The patient requires nitroglycerin based medications continuously (topical/oral/intravenous) - The patient has an arterial pH of < 7.30 or ≥ 7.47 - The patient has clinical and or documented laboratory evidence from routine blood work of renal dysfunction or failure. (Doubling of pre-operative creatinine or requiring dialysis is indicative of renal dysfunction.) - The patient has clinical and or documented laboratory evidence from routine blood work of significant hepatic disease or failure. (ALT or AST 5 times ULN or obvious jaundice will be indicative of liver dysfunction) - The patient's current medical condition in the opinion of the investigator and/or the patient's attending ICU physician makes him/her inappropriate for participation in this study. - The patient is currently a participant in a clinical trial of an investigational therapy including a drug or medical device. - The patient has clinical indications of sepsis defined as 2 of the following five criteria: i) leukocytosis (or) leukopenia: wbc >12 x 109/L (or) <4x109/L (>10% bands also, ii) fever (or) hypothermia (temp >38.5C or <36C), iii) tachycardia, hr > 90 beats/minute, iv) tachypnea, respiratory rate (RR) >18 breaths/minute, v) hypotension, SBP <90 mmHg

Which medical condition, disease, disorder, syndrome, illness, or injury is researched?

Pulmonary Hypertension

Study Interventions

Interventions can include giving participants drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available or noninvasive approaches such as surveys, education, and interviews.

Drug:Sildenafil12.5 mg Sildenafil once with optional second dose

Drug:Sildenafil12.5 mg orally once with optional second dose

Drug:PlaceboOral Placebo in 5 mls distilled water

Study Arms

Research studies and clinical trials typically have two or more research arms. An arm is a group of people who receive the same treatment in the study.

1Oral Sildenafil 12.5 mg

2Placebo in 5 mls distilled water

Study Status

Completed

Start Date: March 2005

Completed Date: May 2009

Phase: Phase 2

Type: Interventional

Design:

Primary Outcome: To determine the efficacy of 12.5mg oral sildenafil to decrease the mPAP in patients presenting with a mPAP >/= 25mmHg after cardiopulmonary bypass.

Secondary Outcome: To determine the efficacy of a second dose of oral sildenafil 12.5mg to decrease the mPAP in those patients who do not respond with a 20% decrease in mPAP after the initial administration of study medication.

Study sponsors, principal investigator, and references

Principal Investigator: David Mazer, MD

Lead Sponsor: St. Michael's Hospital, Toronto

Collaborator: University of Toronto

More information:https://clinicaltrials.gov/show/NCT00334490

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