Predominant determinants for evaluation of right parasternal approach in transthoracic echocardiography in aortic stenosis: a study based on three-dimensional cardiac computed tomography analysis.

The maximum blood flow velocity through the aortic valve (AVmax) using Doppler transthoracic echocardiography (TTE) is important in assessing the severity of aortic stenosis (AS). The right parasternal (RP) approach has been reported to be more useful than the apical approach, but the anatomical rationale has not been studied. We aimed to clarify the influence of the angle formed by the ascending aorta and left ventricle on Doppler analysis by TTE (Sep-Ao angle) and three-dimensional multidetector computed tomography (3D-MDCT) in patients with AS. A total of 151 patients evaluated using the RP approach and 3D-MDCT were included in this study. The Sep-Ao angle determined using TTE was compared with that determined using 3D-MDCT analysis. In MDCT analysis, the left ventricular (LV) axis was measured in two ways and the calcification score was calculated simultaneously. The Sep-Ao angle on TTE was consistent with that measured using 3D-MDCT. In patients with an acute Sep-Ao angle, the Doppler angle in the apical approach was larger, potentially underestimating AVmax. Multivariate analysis revealed that an acute Sep-Ao angle, large Doppler angle in the apical approach, smaller Doppler angle in the RP approach, and low aortic valve calcification were independently associated with a higher AVmax in the RP approach than in the apical approach. The Sep-Ao angle measured using TTE reflected the 3D anatomical angle. In addition to measurements using the RP approach, technical adjustments to minimize the Doppler angle to avoid bulky calcification should always be noted for accurate assessment.

Isolated right ventricular hypoplasia associated with cyanotic atrial septal defect: a case report.

Background: Hypoxaemia in isolated right ventricular (RV) hypoplasia (IRVH) is primarily caused by a right-to-left shunt (RLS) at the atrial level, such as an atrial septal defect (ASD). When considering closure of the RLS, it should be closed only after ensuring that it will not cause right-sided heart failure (HF). Case summary: A 21-year-old woman had been experiencing shortness of breath during exertion since childhood. Transthoracic and transoesophageal echocardiography revealed an ASD with bidirectional shunting, and microbubble test revealed a marked RLS. Cardiac magnetic resonance imaging revealed a hypoplastic RV end-diastolic volume corrected for body surface area of 47 mL/m2 (70% of normal range). Right heart catheterization revealed a decreased Qp/Qs ratio of 0.89 and a pressure waveform with a clear increase in the 'A'-wave, although the mean right atrial pressure was not high (4 mmHg). Therefore, the patient was diagnosed with cyanotic ASD and IRVH. A temporary balloon occlusion test was performed to evaluate the right-sided heart response to capacitive loading prior to ASD closure. After treatment, the patient's improved markedly. The pre-operative brain natriuretic peptide (BNP) level was normal; however, 6 months after ASD closure, the BNP level was elevated, and the continuous-wave Doppler waveform of pulmonary regurgitation at the time of transthoracic echocardiography changed, suggesting an increase in diastolic RV pressure. Discussion: When ASD is complicated by hypoxaemia, the possibility of IRVH, although rare, should be considered. Another difficult point is determining whether the ASD can be closed, considering its immature RV compliance.