Evaluation of Subclinical Right Ventricular Dysfunction in Obstructive Sleep Apnea Patients Using Velocity Vector Imaging

Abstract

bstructive sleep apnea (OSA) is common, underdiagnosed and associated with cardiovascular diseases such as heart failure, left ventricular (LV) and right ventricular (RV) dysfunction, myocardial infarction, arrhythmias, and systemic and pulmonary hypertension. 1 Previous studies have shown the adverse affects of OSA on both LV and RV functions. 2,3 However, many risk factors for OSA, such as excess weight, male sex and advanced age, are the same as the risk factors for cardiovascular diseases. Proving that OSA actually causes cardiac dysfunction independent of these confounding risk factors is difficult. Early recognition of RV dysfunction before pulmonary arterial (PA) hypertension develops is important for preventing further progression to heart failure and even death. 4 Thus, there is a need for a more detailed analysis of its pathophysiologic importance and for techniques that may supplement available technology in identifying early signs of RV impairment. Editorial p 250Recently, tissue Doppler imaging (TDI) and strain/strain rate (SR) imaging have been shown to be reliable and accurate novel techniques for evaluating global and regional ventricular function. 5 As TDI has the disadvantage of being preload and afterload dependent, a new TDI-derived index of isovolumic myocardial acceleration (IVA) has been validated to be a reliable and relatively load independent measure of cardiac systolic function. 6 Velocity vector imaging (VVI) is a novel method based on 2-dimensional B-mode images. The method involves tracking ultrasonic speckles permitting angle-independent measurement of tissue velocity and deformation. 7 It has been shown to be a reliable method for the quantification of regional contractile dysfunction with the ability to detect subclinical cardiac dysfunction. 8 In this study, VVI and TDI were used to evaluate regional subclinical RV dysfunction in newly diagnosed moderate-to-severe OSA The aims of this study were to evaluate subclinical regional right ventricular (RV) dysfunction in newly diagnosed obstructive sleep apnea (OSA) patients without systemic and pulmonary arterial (PA) hypertension, and to correlate OSA severity to RV dysfunction, using both velocity vector imaging (VVI)-derived strain imaging and tissue Doppler imaging (TDI).

Is Right Ventricular Dysfunction in Obstructive Sleep Apnea a Potential Screening Tool?

“…Interestingly, however, they also demon- strated that the correlations between the apnea hypopnea index and VVI/TDI-derived variables remained significant, even after adjustment for mean pulmonary artery pressure. 1 The mechanism of the impaired RV function, which was not associated with LV dysfunction in their study population, remains unknown. OSA has been increasingly implicated in the initiation and progression of cardiovascular diseases.…”

“…1 The difference in pulmonary artery pressure may mechanically affect RV function without compromising the RV myocardium. Interestingly, however, they also demon-…”

“…1 From theoretical considerations, when regional strain is generally reduced in the whole ventricle, the ejection fraction, which is the sum of the regional strains derived from the whole ventricle, should also be reduced, and hence the end-diastolic volume needs to be increased to compensate for normal output. A potential explanation for the discrepancy between the conventional and the VVI/TDI variables may include that the conventional LV and RV measurements are not accurate enough to detect the subtle differences between OSA and control subjects, whereas the TDI and VVI measurements are sensitive enough to differentiate between them.…”

“…1 The difference in pulmonary artery pressure may mechanically affect RV function without compromising the RV myocardium. Interestingly, however, they also demon- strated that the correlations between the apnea hypopnea index and VVI/TDI-derived variables remained significant, even after adjustment for mean pulmonary artery pressure.…”

Radionuclide Evaluation of Contractility of the Right Heart in Mitral Valve Stenosis

“…В то же время, данный метод не позволяет адекватно оце-нить объемы ПЖ, что связано, во-первых, с определен-ными математическими допущениями при использовании модели Симпсона [3] и, во-вторых, с загрудинным распо-ложением свободной стенки ПЖ, что зачастую определяет сложности ее ультразвуковой визуализации [4].…”