Chest
Volume 125, Issue 6, June 2004, Pages 2121-2128
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Clinical Investigations
Cardiology
Feasibility of Routine Pulmonary Arterial Impedance Measurements in Pulmonary Hypertension

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Objectives

Right ventricular (RV) afterload is best described by a pulmonary arterial impedance (PVZ) spectrum, which integrates pulmonary vascular resistance (PVR), elastance, and wave reflection. We evaluated the feasibility of PVZ determinations in patients with pulmonary arterial hypertension (PAH) during routine right heart catheterization and Doppler echocardiography.

Design

Prospective study.

Setting

Academic hospital. Patients: Twenty-two patients with PAH.

Interventions

Right heart catheterization with a fluid-filled Swan-Ganz catheter, Doppler echocardiography, and administration of inhaled nitric oxide (NO) [10 to 20 ppm; 17 patients], maximum tolerated dose of IV epoprostenol (average, 8.5 ng/kg/min; 5 patients), and IV dobutamine (8 μg/kg/min; 8 patients).

Measurements and results

PVZ was calculated from the spectral analysis of synchronized pulmonary artery pressure (Ppa) and flow waves. The mean (± SE) Ppa was 63 ± 3 mm Hg, and the mean PVR was 16 ± 2 Wood units. The PVZ spectrum was markedly shifted to higher than normal pressures and frequencies, with a mean 0-Hz impedance (Z0) of 1,506 ± 138 dyne · s · cm−5, and a mean characteristic impedance (Zc) of 124 ± 11 dyne · s · cm−5, which are in keeping with data from previous studies. Inhaled NO levels decreased Ppa, PVR, Z0, and Zc without a change in cardiac output. Epoprostenol administration did not affect Ppa, increased cardiac output, and decreased Z0 and Zc. Dobutamine administration increased cardiac output and Ppa, and decreased PVR and Z0, without changing Zc.

Conclusions

The determination of PVZ to quantify RV afterload is feasible during routine right heart catheterization and Doppler echocardiography. The measurement is sensitive to pharmacologic interventions.

Section snippets

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

Effects of Pulmonary Hypertension

As shown in Table 1, the patients had increased levels of Ppa, Pra, and PVR, a normal Ppao level, and decreased cardiac output, with a PVZ spectrum showing marked increases in Z0, Z1, and Zc, a shift of Fmin to higher frequencies, and a negative first harmonic phase angle, with Z0 cross-shifted to higher frequencies (Table 1). Representative PVZ spectra with source pressure and flow signals are shown in FIGURE 1, FIGURE 2, FIGURE 3.

Compared to previously reported primary pulmonary hypertension

DISCUSSION

The present results show that it is possible to analyze Ppa and flow waves obtained during routine right heart catheterization with thermodilution fluid-filled pulmonary artery catheters and concomitant transthoracic Doppler echocardiography. Derived PVZ spectra are realistic, as they were similar to those previously reported with sophisticated high-fidelity equipment, and were sensitive to pharmacologic interventions.

Right heart catheterization for the diagnosis and therapeutic follow-up of

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  • Cited by (0)

    This research was supported by grant No. 3.4516.02 from the Fonds de la Recherche Scientifique Médicale and by the Foundation for Cardiac Surgery, Belgium. Sandrine Huez is fellow of the Fonds National de la Recherche Scientifique, Belgium.

    Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (e-mail: [email protected]).

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