Intravascular Ultrasound Best to Identify Pulmonary Hypertension

Laurie Barclay, MD

March 26, 2003

March 26, 2003 — Intravascular ultrasound (IVUS) may be the procedure of choice to identify pulmonary hypertension, according to the results of a prospective observational study published in the March issue of Heart. Functional state determined by this method correlated with mortality.

"IVUS has been validated as a reliable method for describing pulmonary vessel wall morphology and pulmonary artery pulsatility," write Josep Rodés-Cabau, from Universitari Vall d'Hebron in Barcelona, Spain, and colleagues. "It is a unique form of exploration that can provide a simultaneous morphological and functional evaluation of the pulmonary vasculature."

Of 20 consecutive patients with primary pulmonary hypertension admitted to a tertiary referral hospital, 16 were women; mean age was 39 ± 14 years. Cardiac catheterization and simultaneous IVUS of pulmonary artery branches at baseline and after infusion of epoprostenol allowed imaging of 33 pulmonary arteries with a mean diameter of 3.91 ± 0.80 mm. IVUS did not provide adequate images for morphological evaluation in up to 25% of the pulmonary arteries evaluated, and two patients were excluded because of the poor quality of the images.

All 33 pulmonary arteries had thickened walls, with mean wall thickness of 0.37 ± 0.13 mm, and thickening was eccentric in 64%. Mean percentage wall area was 31.0% ± 9.3%, pulsatility was 14.6% ± 4.8%, and pulmonary/elastic strain index was 449 ± 174 mm Hg. There was no correlation between IVUS findings and hemodynamic variables. Regardless of hemodynamic changes, epoprostenol infusion increased pulsatility by 53% and decreased the pulmonary/elastic strain index by 41% ( P = .0001).

At mean follow-up of 18 months, nine patients had died. Reduced pulsatility and increased pulmonary/elastic strain index predicted increased mortality at follow-up. Pulsatility was 12.0% ± 4.4% in survivors and 16.4% ± 4.4% in those who subsequently died ( P = .03). Corresponding values for pulmonary/elastic strain index were 369 ± 67 vs. 546 ± 216 mm Hg, respectively ( P = .02).

"IVUS provides combined morphological and functional evaluation of the elastic pulmonary vessels of patients with primary pulmonary hypertension and allows direct assessment of the acute changes induced in the pulmonary vessel wall dynamics by epoprostenol. The exploration is safe, and can be undertaken at the same time as cardiac catheterization," the authors write. "There is an association between impaired pulmonary artery functional state as determined by IVUS and mortality at follow up. However, larger series are needed to determine the exact prognostic value of this technique in the setting of primary pulmonary hypertension."

Heart. 2003;89:311-316

Reviewed by Gary D. Vogin, MD