Assessment of the pulmonary volume pulse in idiopathic pulmonary arterial hypertension by means of electrical impedance tomography.
BACKGROUND
Electrical impedance tomography (EIT) is a non-invasive imaging technique which can be used to measure the blood volume changes in the pulmonary vascular bed during the cardiac cycle.


OBJECTIVE
This study was performed to evaluate the differences in the EIT signal of the pulmonary vascular bed between healthy subjects and patients with idiopathic pulmonary arterial hypertension (IPAH), who are known to have a remodelled pulmonary vascular bed.


METHODS
Twenty-one patients (17 females, 4 males) with IPAH and 30 healthy controls (5 females, 25 males) were measured. EIT measurements were performed in duplicate, on the same day as right heart catheterization to obtain haemodynamic data. The maximal impedance change during systole (Delta Z(sys)) was used as a measure of the pulmonary volume pulse and expressed in arbitrary units (AU). Total lung capacity, spirometric values and diffusion capacity for carbon monoxide were measured as well.


RESULTS
Mean Delta Z(sys) was 215 +/- 58 x 10(-2) AU (95% CI 193 x 10(-2) to 236 x 10(-2)) in the healthy subjects and 78 +/- 27 x 10(-2) AU (95% CI 66 x 10(-2) to 91 x 10(-2)) in the IPAH patient group (p < 0.0001). No significant correlation was found between Delta Z(sys) and any of the haemodynamic or lung function data.


CONCLUSIONS
The impedance pulsation of the pulmonary vascular bed is reduced in IPAH in comparison with controls, indicating a reduced volume pulse. This might represent the reduced cross section area, as well as the reduced compliance and number of the pulmonary vessels in these patients.
Smit
Henk J
HJ
Department of Pulmonary Diseases, VU Medical Center, Amsterdam, The Netherlands. smit@henkjan.speedlinq.nl
Vonk-Noordegraaf
Anton
A
Boonstra
Anco
A
de Vries
Peter M
PM
Postmus
Pieter E
PE
D000293:Adolescent; D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D017097:Electric Impedance; D005260:Female; D006801:Humans; D006976:Hypertension, Pulmonary / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D011651:Pulmonary Artery / Q000503:physiopathology*; D011652:Pulmonary Circulation; D011674:Pulse; D012129:Respiratory Function Tests; D014054:Tomography