Optimal Albunex dosing for enhancement of Doppler tricuspid regurgitation spectra

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

BACKGROUND

Accurate evaluation of the tricuspid regurgitant (TR) spectral Doppler signal is important during transthoracic echocardiographic (TTE) evaluation for pulmonary hypertension (PHT). Contrast enhancement improves Doppler backscatter. However, its incremental benefit with contemporary scanners is less well established. The aim of this study was to assess whether the TR spectral Doppler signal using contemporary scanners was improved using a second generation contrast agent, Definity® (CE), compared to unenhanced TTE (UE).

METHODS

Analysis of patients who underwent UE then CE TR interrogation was performed. TR signal was evaluated by an experienced reader and graded 1 (clear-high level of confidence of interpretation and complete spectral Doppler envelope), 2 (suboptimal with medium-low level of confidence of interpretation and incomplete envelope), 3 (poor-absent and no measurable spectral Doppler signal). Maximal TR velocity (TRV) was defined as peak velocity that could be clearly identified. An inexperienced sonographer read 30 randomly selected studies.

RESULTS

176 TTE were performed in 173 patients (mean age 57 ± 14.8 years). Wilcoxon signed rank test demonstrated significant improvement (p < 0.0001) in TR spectral Doppler signal quality with CE TTE. Mean score CE TTE vs. TTE = 2.32 ± 0.85 vs. 2.56 ± 0.75 respectively (p < 0.0001). Mean maximal TRV CE TTE vs. UE TTE = 2.61 ± 0.44 m/s vs. 2.54 ± 0.49 m/s respectively (p < 0.0001). The inexperienced reader had a greater improvement in scoring CE TTE signals vs. UE TTE (p < 0.0001).

CONCLUSION

In the era of contemporary scanners, CE improved the ability to detect and measure TRV, except in those with clear unenhanced TR spectral Doppler signals or greater than mild tricuspid regurgitation.

Echocardiographic Assessment of Right Heart Hemodynamic Parameters

Echocardiography is currently the primary clinical method for the noninvasive measurement of right heart hemodynamic parameters and is an indispensable tool for the initial assessment, diagnosis, longitudinal follow-up, and prognostication of patients with abnormal right heart function. This review will discuss the echocardiographic methods used to estimate right heart hemodynamic parameters.

The usefulness of a 10% air-10% blood-80% saline mixture for contrast echocardiography: Doppler measurement of pulmonary artery systolic pressure

OBJECTIVES

We assessed an air-blood-saline mixture for Doppler measurement of pulmonary artery systolic pressure (PASP) and the mechanism of enhancement of the Doppler signal by this mixture.

BACKGROUND

Underestimation of PASP by Doppler echocardiography occurs with inadequate continuous wave (CW) signals of tricuspid regurgitation (TR).

METHODS

We assessed in vitro the diameter and concentration of microbubbles of agitated air-saline mixture, air-blood-saline mixture and 10% air-10% plasma-80% saline mixture immediately, 5, 10 and 20 s after agitation. In 20 patients, PASP was estimated by Swan-Ganz catheter and CW Doppler of TR: 1) without contrast injection; 2) with intravenous injection of 10% air-90% saline; and 3) 10% blood-10% air-80% saline mixture.

RESULTS

Compared to air-saline, addition of blood or plasma to the air-saline solution significantly increased the concentration of microbubbles (p < 0.001). The air-blood-saline (26.7 +/- 7.2 microm) and air-plasma-saline mixture (25.3 +/- 7.4 microm) had smaller microbubbles than air-saline mixture (31.6 +/- 8.2 microm) (p < 0.001). The correlation between Doppler- and catheter-measured PASP at baseline (r = 0.64) improved with agitated air-saline (r = 0.86). With the air-blood-saline mixture, the correlation further improved (r = 0.92) and the best limits of agreement were obtained.

CONCLUSIONS

The combination of the patient's own blood is a method of making a sterile solution of numerous small microbubbles for injection into the right-sided cardiac chambers. Clinically, the air-blood-saline mixture is easily prepared at bedside and is superior to the air-saline mixture in assessing PASP in patients with inadequate CW Doppler signals.

Echo contrast-enhanced diagnosis of atrial septal defect

Pulsed wave, continuous wave, and color flow Doppler imaging as well as intravenously administered agitated saline solution can detect intracardiac shunts during transthoracic echocardiography. Ultrasonographic contrast agents have greatly improved the visualization of left heart chambers and can enhance signals from blood flow within chambers and across valves, increasing the sensitivity of Doppler techniques. We describe a patient in whom the use of echo contrast media during transthoracic echocardiography allowed the detection of a previously unseen atrial septal defect. Combining such modalities may help to increase the sensitivity of transthoracic echocardiography and may eliminate the need for transesophageal echocardiography in selected patients.

Contrast Echocardiography in Clinical Practice

After FDA approval of the new-generation contrast agent Optison (Mallinckrodt Medical, St. Louis, MO) January 1998, the use of contrast in echocardiograhy has become an invaluable tool. A review of 100 patients revealed contrast to be useful for endocardial border definition and wall segment analysis, enhancement of pulsed Doppler, and chamber opacification for the detection of thrombi. Evaluation of wall segments by two observers before and after injection of the contrast agent revealed an increase in the number of wall segments visualized by 4.8. Postinjection readings were consistent between the two observers. Routine contrast echocardiography may provide a more diagnostic study.

Estimation of the systolic pulmonary arterial pressure using contrast-enhanced continuous-wave Doppler in patients with trivial tricuspid regurgitation

Noninvasive estimation of pulmonary arterial pressure is important for hemodynamic monitoring of patients with heart disease. In patients with tricuspid regurgitation (TR), the peak velocity of TR on continuous-wave (CW) Doppler can be used to estimate the systolic pulmonary arterial pressure (PAPs) using the simplified Bernoulli equation. We evaluated a new technique of contrast-enhanced CW Doppler for calculating PAPs in patients with trivial TR. Forty-one patients without visible TR detected by color Doppler, pulsed Doppler or CW Doppler were evaluated. Age ranged from 19 to 73 (55 +/- 12) years old. Tricuspid flow signals were recorded on CW Doppler after intravenous administration of indocyanin green (ICG) or Albunex. PAPs was calculated as; PAPs = 4 x VTR2 + 10 mmHg, where VTR is the peak velocity of TR. PAPs calculated using contrast-enhanced CW Doppler was compared with PAPs measured by the following cardiac catheterization. 1) TR signals were recorded using the contrast-enhanced CW Doppler technique in 39 of 41 patients (95%) after intravenous administration of contrast agents. 2) The error of estimate of PAPs using the contrast-enhanced CW Doppler technique was -2.4 +/- 7.5 mmHg, and the percent error was -10.7 +/- 32.4% in all patients. In 20 of 39 patients (51%), the error of estimate was within +/- 5 mmHg. 3) PAPs was overestimated by 12.2 +/- 6.1 mmHg in patients with good contrast enhancement of TR signals. The contrast-enhanced CW Doppler technique is useful for estimating PAPs noninvasively in patients with trivial TR. It is better to assume the right atrial pressure as 3-5 mmHg, not 10 mmHg, in patients with good enhancement of trivial TR. Physiological TR may be enhanced by contrast agents in these patients.

Tricuspid valve disease. Clinical evaluation, physiopathology, and management

The tricuspid and mitral valves are homologous whose function depends on coordination among components. Isolated tricuspid valve abnormalities are relatively uncommon. Rheumatic disease, chemicals, immunologic and degenerative disorders alter leaflet anatomy and may result in either stenosis, insufficiency or a combination. More often, tricuspid disorders present as a component of congenital syndromes or secondary to pulmonary vascular or let heart disease which alter geometry and function of nonleaflet components.

Contrast echocardiography: review and future directions

Recent developments and advances in contrast echocardiography have been made to improve the diagnosis and evaluation of cardiac structures and function. By coupling new developments in acoustic instrumentation with new contrast agents, information that was previously difficult or impossible to gather by standard 2-dimensional echocardiography can now be obtained. Numerous studies have been published confirming the advantages of using contrast during echocardiographic studies, particularly with stress testing and myocardial perfusion. This review aims to summarize (1) the various contrast agents that are available or being developed; (2) factors that have been found to affect the strength of enhanced signals; (3) the new developments in instrumentation that improve the ability of scanners to differentiate echo contrast from cardiac tissue; and (4) the documented and possible future uses of contrast echocardiography.