Noninvasive evaluation of systolic pressures of pulmonary artery and right ventricle using contrast-enhanced doppler echocardiography: Comparative study using sonicated albumin or glucose solution

Abstract

Evaluation of pulmonary arterial pressure is essential for the diagnosis and management of patients with congenital heart disease; it is usually done by cardiac catheterization. An alternative, noninvasive method may be clinically more useful. The purpose of this study was to assess the usefulness of the noninvasive determination of systolic pressure of the pulmonary artery and right ventricle by contrast-enhanced Doppler echocardiography. We selected 30 pediatric patients (28 with trivial or nonsignificant tricuspid regurgitant Doppler signals and 2 with significant tricuspid regurgitant Doppler signals) aged 2 months to 21 years. The flow velocity of tricuspid regurgitation was measured with continuous-wave Doppler of the right ventricular inflow view or left parasternal or apical four-chamber view before and after injection of two types of contrast medium (hand-agitated 5% glucose or sonicated albumin). The systolic pressure of the pulmonary artery was assessed as the estimated right ventricular systolic pressure (albumin method) minus the peak pressure gradient across the pulmonary valve (nonenhanced Doppler method). After injection of hand-agitated 5% glucose and sonicated albumin, trivial tricuspid regurgitation signals were enhanced in 25 of 28 patients (89%). In two patients, spectral envelopes were well defined enough to obtain the peak systolic velocity of the tricuspid regurgitation jet without contrast medium injection. Peak velocity was not altered by injection of contrast medium in these patients. There was significant correlation between the estimation by contrast-enhanced Doppler using hand-agitated 5% glucose and the cardiac catheterization measurement of the transtricuspid pressure gradient (r = 0.88). The transtricuspid pressure gradients obtained by continuous-wave Doppler during sonicated albumin enhancement corresponded closely to those measured by cardiac catheterization (r = 0.95). Pulmonary arterial and right ventricular systolic pressures measured by Doppler using sonicated albumin and those obtained by cardiac catheterization were highly correlated (right ventricle, r = 0.96; pulmonary artery, r = 0.95). In conclusion, this technique may be a valuable noninvasive method for determining accurate right ventricular and pulmonary arterial systolic pressures.

Contrast microsphere enhancement of the tricuspid regurgitant spectral Doppler signal - Is it still necessary with contemporary scanners?

“…One of the limitations of this technique is that the backscatter generated by this technique is a relatively course, heterogeneous and unstable reflector of ultrasound. Limitations of agitated saline, most likely due to the relatively large size, low number, short term and unstable nature of the bubble [24] , [25] include over-estimation of the velocity in patients with trivial tricuspid regurgitation and not having as good correlation with catheter derived RVSP compared to an air-blood-saline contrast mixture [22] , [26] , [27] , [28] . As such, it is not uncommon for agitated saline to produce course, incomplete spectral Doppler envelopes.…”

“…Echocardiographic contrast microspheres have been used in routine clinical practice since the mid 1990's [7] , [30] , [31] . As a strong backscatterer of ultrasound, these agents can also be used to optimise a spectral Doppler signal, either on the left or right side of the heart [28] , [29] , [32] , [33] , [34] , [35] . However, all these studies have used a first generation contrast agent such as sonicated albumin or Levovist © (Bayer, Germany).…”

Effects of hydralazine on the pulmonary vasculature and respiratory control in humans

“…However, there is now a lot of experimental evidence: (1) to support the accuracy of this technique as an index of peak pulmonary systolic pressure in both euoxia (Yock et al 1986) and hypoxia (Allemann et al 2000); and (2) to show that peak systolic pressure is tightly related to the mean pulmonary arterial pressure (Yock et al 1986;Chan et al 1987;Ishii et al 1996).…”

Assessment of Right Ventricular Function

“…Characterization of tricuspid valve regurgitation flow with Doppler can be valuable in the noninvasive estimation of RV and PA systolic pressure when the peak regurgitation velocity is combined with estimates of RA pressure. 43 Furthermore, determining the severity of tricuspid regurgitation can help ascertain clinical utility of thermodilution ejection fraction measurements. Pulmonary arterial images in cross-section and Doppler flow characteristics can be used to assess RV afterload from PA distensibility, contractility from flow acceleration, and cardiac output from the product of PA area and velocity.38,44 Some investigators have reported that Doppler characterization of hepatic venous flow patterns also provides valuable indirect information regarding right heart function.…”