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Feasibility of Routine Pulmonary Arterial Impedance Measurements in Pulmonary Hypertension: Materials and Methods

There are only a few previous studies, on PVZ in PAH patients. This is to be explained by the technical difficulties of instantaneous pressure and flow measurements requiring high-fidelity, manometer-tipped catheters and flowmeters. It has been generally assumed that the frequency response of the fluid-filled thermodilution Swan-Ganz catheters that are used for routine right heart catheterizations would be insufficient for instantaneous pressure measurements but would be acceptable for mean pressure estimations. On the other hand, flow measured by thermodilution using these catheters necessarily covers several cardiac cycles, imposing the steady flow hemodynamic approach. However, the natural frequency of commercially available Swan-Ganz catheters is around 30 Hz, decreasing to only 18 to 20 Hz for the external manometer-tubing-pulmonary catheter system, which actually may be adequate for valid and clinically relevant pressure wave measurements. Instantaneous pulmonary artery flow velocities can be measured by transthoracic pulsed Doppler echocardiography. type two diabetes medications

Therefore, we evaluated the feasibility of performing instantaneous Ppa and flow measurements during a routine right heart catheterization that was combined with Doppler echocardiography in patients with PAH. We compared the obtained PVZ calculation to those values previously reported in PAH patients and evaluated its sensitivity to pharmacologic interventions,
Study Population
Twenty-two patients (5 men and 17 women; mean age, 46 years) with PAH gave informed consent to participate in this study, which was approved by the Institutional Review Board of the Erasme University Hospital. PAH was defined by an increase in Ppa values without identifiable cardiac or pulmonary cause, and possibly associated with conditions such as appetite-suppressant intake, connective tissue disease, liver cirrhosis, HIV infection, and congenital left-to-right shunts, as defined by a World Health Organization-sponsored expert consensus conference held in 1998 in Evian. PAH was primary (ie, with no identifiable associated conditions) in 14 patients, and was associated with the intake of appetite suppressants (fenfluramines) in 3 patients, with systemic-to-pulmonary congenital cardiac shunts in 4 patients, and with portal hypertension in 1 patient. The patients were in New York Heart Association (NYHA) functional class III, excepted for two patients who were in NYHA class IV and one patient who was in NYHA class II. The patients had been referred for diagnostic evaluation before the administration of prostacyclin or endothelin receptor blocker therapy. All but 3 patients were receiving conventional treatment, consisting of anticoagulants in 15 patients, diuretics in 13 patients, low-dose nifedipine in 4 patients, and digoxin in 1 patient.