Doppler tissue imaging in assessment of pulmonary hypertension-induced right ventricle dysfunction

Abstract

-We aimed to assess the accuracy of Doppler tissue imaging (DTI) in detecting right ventricle (RV) dysfunction and electromechanical coupling alteration following pulmonary hypertension (PHT) in rat. PHT was induced by chronic hypoxia exposure (hypoxic PHT) or monocrotaline treatment (monocrotaline PHT). In both PHT models, we observed transparietal RV pressure increase and remodeling, including hypertrophy and dilation. Conventional echocardiography provided evidence for pulmonary outflow impairment with midsystolic notch and acceleration time decrease in PHT groups (21.7 Ϯ 1.6 and 13.2 Ϯ 2.9 ms in hypoxic and monocrotaline PHT groups vs. 28.1 Ϯ 1.0 ms in control). RV shortening fraction was decreased in the monocrotaline PHT group compared with the hypoxic PHT and control groups. Combining conventional Doppler and DTI was more helpful to detect RV diastolic dysfunction in the monocrotaline PHT group (E/Ea ratio ϭ 17.0 Ϯ 1.4) compared with the hypoxic PHT and control groups (11.5 Ϯ 0.7 and 10.2 Ϯ 0.4, respectively). Tei index measured using DTI highlighted global RV dysfunction in the monocrotaline PHT group (1.36 Ϯ 0.24 vs. 0.92 Ϯ 0.05 and 0.86 Ϯ 0.05 in the hypoxic PHT and control groups, respectively). Q-S m time measured from the onset of Q wave to the onset of DTI S m wave was increased in both PHT groups. PHT-induced electromechanical coupling alteration was confirmed by in vitro activation-contraction delay measurements on isolated RV papillary muscle, and both Q-S m time and activation-contraction delay were correlated with PHT severity. We demonstrated that Q-Sm time measured in DTI was an easily and convenient index to detect early RV electromechanical coupling alteration in both moderate and severe PHT. echocardiography; hypertrophy; right ventricular remodeling CHRONIC ALVEOLAR HYPOXIA, which often occurs in patients suffering from chronic obstructive pulmonary diseases, secondarily induces a sustained increase in pulmonary artery resistance. The subsequent pulmonary artery hypertension (PHT) leads to right ventricle (RV) pressure overload and hypertrophy (22).Conventional transthoracic echocardiography is widely used to detect PHT in humans and animal models (14, 18). The standard parameters are the RV free wall thickening recorded in time-motion (TM) mode, the presence of mild-systolic notch, and the acceleration time decrease in the pulmonary outflow spectrum recorded in pulsed-Doppler mode. Nevertheless, a more extensive assessment of PHT-induced RV dysfunction remains difficult using conventional echocardiography. Indeed, accuracy of RV systolic and diastolic functions assessment is limited by complex anatomy and geometry of the ventricle.The Tei index, which combines both systolic and diastolic parameters, was suggested to determine global myocardial performance (27). It has been used in the assessment of RV dysfunction, especially in PHT (26). In conventional pulsed Doppler, the Tei index derives from both isovolumic contraction and relaxation times (IVCT and IVRT) as well as ejection time of...

Diagnostic Value of Echo-Doppler and Tissue Doppler Imaging in Dogs with Pulmonary Arterial Hypertension

“…16 Tissue Doppler imaging (TDI) is an ultrasound technique that allows quantitative assessment of segmental myocardial motion. 17,18 Quantitative TDI assessment of regional RV myocardial velocities has already been performed in the awake dog, and TDI has been shown to be a repeatable and reproducible method for evaluating basal RV function in this species. 19 A strong correlation has been demonstrated between PAPand several TDI-derived variables in humans.…”

“…19 A strong correlation has been demonstrated between PAPand several TDI-derived variables in humans. 17,[20][21][22][23] However, to our knowledge, the diagnostic value of right TDI variables has never been assessed in the context of spontaneous canine Doppler-derived evidence of PAH.…”

Alterations in Pharmacological Action of the Right Ventricle of Monocrotaline-Induced Pulmonary Hypertensive Rats

“…8 that reported by others. 17,18) The Masson's trichrome staining of the 6w-MCT rats showed a marked interstitial fibrosis in the right ventricle, which was responsible for the increase in the RVSP along with time after MCT administration. It is apparent that cardiac hypertrophy and fibrosis in the myocardium is a possible cause for cardiac dysfunction.…”

Alterations in Dystrophin-Related Glycoproteins in Development of Right Ventricular Failure in Rats

“…The alterations in the RVW and the ratios related to them suggest the genesis of right ventricular hypertrophy in this model. Since the ratio of right ventricular weight / (left ventricular weight + septum weight) is considered to be a marker of right ventricular hypertrophy (17,20,31), augmentation of this ratio for the MCT rats clearly represents the genesis of right ventricular hypertrophy.…”