Study Population

A total of 70 consecutive patients with PH (22 men; mean age, 41 ± 15 years) were enrolled in this study. Patients were admitted to the Division of Cardiology or the Division of Cardiac Surgery at Zhongshan Hospital of Fudan University from December 2010 to April 2011. Forty-seven patients were diagnosed with pulmonary arterial hypertension (six idiopathic, 27 with atrial septal defects, eight with ventricular septal defects, and six with patent ductus arteriosus), and 23 patients were diagnosed with PH with left-sided valvular heart disease. The diagnosis of PH was made according to the American College of Cardiology and American Heart Association 2009 expert consensus document on PH. Exclusion criteria for patient selection were age < 18 or > 60 years, atrial fibrillation, and inadequate transthoracic echocardiographic window. Twenty-six healthy subjects were included as a control group.

Conventional echocardiography and RT3DE were performed in all patients and controls. According to pulmonary artery systolic pressure (PASP) measured by echocardiography, patients with PH were classified into groups with mild PH (PASP, 40–49 mm Hg), moderate PH (PASP, 50–69 mm Hg), and severe PH (PASP ≥ 70 mm Hg). Seventeen of the 70 patients (24%) underwent right heart catheterization (RHC) <24 hours after echocardiographic image acquisition. RHC-derived hemodynamic parameters including PASP and pulmonary vascular resistance (PVR) were recorded. This study was approved by the ethics committee of Zhongshan Hospital, affiliated to Fudan University.

Conventional Echocardiography

Conventional echocardiographic images of all subjects were obtained using an iE33 ultrasound machine with an S5-1 transducer (Philips Medical Systems, Andover, MA). Heart rate was recorded and left ventricular ejection fraction (EF) was calculated using the biplane method. RV end-diastolic longitudinal and midcavity diameters were measured from a right ventricle–focused apical four-chamber view. RV end-diastolic and end-systolic areas were measured to calculate RV fractional area change (FAC). PASP was estimated from the peak continuous-wave Doppler velocity of the tricuspid regurgitation (TRV) plus right atrial pressure according to the modified Bernoulli equation, PASP (mm Hg) = 4 × TRV ² + right atrial pressure, where right atrial pressure was assessed by inferior vena cava diameter and collapsibility. The time-velocity integral was determined from pulsed-wave Doppler in the RV outflow tract. Estimated PVR was calculated using the equation PVR (Wood units) = TRV/time-velocity integral × 10 + 0.16, as suggested by Abbas et al. With the pulsed-wave Doppler sample volume positioned at the lateral margin of the tricuspid annulus in the apical four-chamber view, the peak tissue Doppler systolic velocity of the tricuspid annulus was measured and the RV myocardial performance index (MPI) was calculated as the ratio of isovolumic time divided by ejection time of the right ventricle.

RT3DE

RT3DE was performed in all subjects after the two-dimensional examination using an iE33 ultrasound machine with an X3-1 matrix-array transducer (Philips Medical Systems). RV 3D images were acquired in a full-volume set in the apical four-chamber view. The acquisition of RV 3D images was conducted twice, with a time interval of within 5 min, and the acquired images were stored on a compact disc.

Postprocessing of real-time 3D echocardiographic images was performed using a TomTec workstation with four-dimensional analysis software (EchoView, TomTec Imaging Systems GmbH, Munich, Germany). The software analyzed real-time 3D echocardiographic images in a semiautomatic way. With the observer manually tracing end-diastolic and end-systolic frames in the sagittal, four-chamber, and coronal views obtained from real-time 3D images, the software automatically traced the RV inner border during one heart cycle, recording RV chamber volume changes, calculating RV global end-diastolic volume (EDV), end-systolic volume, stroke volume, and EF, and developing an immediate report. At the same time, the 3D chamber of the right ventricle was divided into three parts, the inflow, body, and outflow compartments, on the basis of the RV surface landmarks by the software automatically ( Figure 1 ). These landmarks were defined at 50% of the distance between the point of the tricuspid annular border, the apical point, and the point of the pulmonary annular border. We converted the digital record of RV regional volumes over one heart cycle into a spreadsheet to form a volume-time curve ( Figure 2 ). The maximum and minimum values of regional volumes were detected as regional EDV and end-systolic volume. Regional stroke volume and EF were then calculated as the difference and the percentage change of EDV and end-systolic volume, respectively. Furthermore, we detected RV regional time to minimum systolic volume (Tmsv) and Tmsv corrected by heart rate (Tmsv%) by reading the digital record of RV regional volumes over one heart cycle to calculate RV systolic dyssynchrony indices, including the standard deviations of Tmsv and Tmsv% in three RV segments.

Postprocessing of real-time 3D echocardiographic image of the right ventricle. ( Top left ) Original real-time 3D echocardiographic image. ( Top right ) Semiautomatic tracing of the RV inner border. ( Bottom left ) Three-dimensional model of RV chamber generated by real-time 3D echocardiographic analysis software. ( Bottom right ) Segmentation of the three regions of the right ventricle.

Regional volume-time curve of the right ventricle according to real-time 3D echocardiographic data. The three compartments of the right ventricle reach the minimum regional systolic volume more simultaneously in a normal controls ( left ) than in a patient with severe PH ( right ).

Measurement Variability

Using the methods described above, 20 randomly chosen real-time 3D echocardiographic images were analyzed by two observers and by one observer with a minimum time interval of 2 weeks for the measurement of regional EF and dyssynchrony indices. The measurements were performed on the same cardiac cycle of the same image. All readers were blinded to previous measurements. Interobserver and intraobserver variability was assessed using the coefficient of variation (the absolute difference between repeated measurements as a percentage of their mean value) and Bland-Altman analysis.

Statistical Analysis

Statistical analysis was performed using SPSS version 16.0 (SPSS, Inc., Chicago, IL). Categorical data, presented as numbers, were compared using χ ² tests. Continuous variables are expressed as mean ± SD. Conventional and real-time 3D echocardiographic parameters of RV dimensions and systolic function were compared between groups using Student’s unpaired t tests. Differences among three or more groups were assessed using one-way analysis of variance. Correlations between two variables were evaluated using Pearson’s rank correlation coefficient. All tests were two sided, and P values <.05 were considered statistically significant.

Clinical and Conventional Echocardiographic Characteristics

Conventional echocardiographic images were successfully obtained and analyzed in all subjects. Clinical and conventional echocardiographic characteristics of the study population are summarized in Table 1 . There were no significant differences in age, gender, peak tissue Doppler systolic velocity of the tricuspid annulus, and left ventricular EF between the PH groups and the control group. Heart rates in the moderate and severe PH groups were higher than in the control group. RV end-diastolic midcavity diameter and RV end-systolic area were higher in all PH groups than in the control group. RV end-diastolic longitudinal diameter and RV end-diastolic area were higher in the severe PH group than in the control group. FAC was lower in all PH groups than in the control group and was the lowest in the severe PH group. MPI was prolonged in all the PH groups compared with the control group and changed most significantly in the severe PH group. TRV/time-velocity integral and PVR were higher in all PH groups than in the control group and were highest in the severe PH group.

Real-Time 3D Echocardiographic Measurements

Real-time 3D echocardiographic images of the right ventricle were successfully analyzed in 68 of the 70 patients (97%) and 25 of the 26 controls (96%). Image quality was inadequate to be analyzed in two patients and one control because of unsatisfactory echocardiographic windows. The mean times for image acquisition and analysis were 3 ± 1 min and 6 ± 2 min, respectively. RV global and regional EFs measured by RT3DE were correlated with FAC, peak tissue Doppler systolic velocity of the tricuspid annulus, and MPI in all subjects ( r = 0.24–0.58, P < .05).

Real-time 3D echocardiographic parameters regarding RV regional systolic function and dyssynchrony are summarized in Table 2 . Compared with controls, inflow EF and global EF were lower in all PH groups ( P < .05), while body EF was decreased in the moderate and severe PH groups ( P < .05) and outflow EF was changed in the severe PH group ( P < .001). Regional and global EFs in the severe PH group were lowest among the three PH groups. Regional and global EDVs in the PH groups were larger than in the controls. The standard deviations of Tmsv% in the mild and moderate PH groups were similar to that in the control group and significantly prolonged in the severe PH group ( P < .05). Figure 2 shows that the three RV compartments reached the minimum regional systolic volume more simultaneously in a normal control than in a patient with severe PH. Differences of other real-time 3D echocardiographic parameters between the patients and control groups were not significant.

Table 2

Regional systolic function and Tmsv of the right ventricle measured by RT3DE

	Control	Mild PH	Moderate PH	Severe PH
Variable	( n = 25)	( n = 12)	( n = 23)	( n = 33)
Body EF (%)	52.9 ± 8.2	47.6 ± 8.7	42.4 ± 5.3 ∗	27.8 ± 9.6 ∗ † ‡
Body EDV (mL)	21.7 ± 7.0	54.3 ± 27.8 ∗	52.0 ± 41.7 ∗	57.5 ± 29.4 ∗
Outflow EF (%)	55.7 ± 11.1	53.3 ± 8.9	50.55 ± 12.8	39.4 ± 13.9 ∗ † ‡
Outflow EDV (mL)	18.4 ± 5.3	33.7 ± 17.3 ∗	38.2 ± 26.0 ∗	34.8 ± 15.6 ∗
Inflow EF (%)	66.4 ± 6.8	59.6 ± 7.6 ∗	58.3 ± 8.1 ∗	41.3 ± 11.4 ∗ † ‡
Inflow EDV (mL)	38.8 ± 9.8	65.5 ± 33.8 ∗	82.0 ± 41.9 ∗	76.5 ± 27.0 ∗
Global EF (%)	60.5 ± 6.4	54.8 ± 6.0 ∗	53.4 ± 7.0 ∗	36.4 ± 9.4 ∗ † ‡
Global EDV (mL)	79.1 ± 18.8	153.3 ± 59.5 ∗	178.3 ± 101.6 ∗	168.6 ± 67.9 ∗
Standard deviation of Tmsv (msec)	6.3 ± 4.5	8.7 ± 8.4	12.1 ± 12.4	13.6 ± 13.6
Standard deviation of Tmsv% (%)	0.7 ± 0.5	1.2 ± 0.9	1.47 ± 1.58	2.0 ± 2.1 ∗

Only gold members can continue reading. Log In or Register to continue

Share this:

• Click to share on Twitter (Opens in new window)
• Click to share on Facebook (Opens in new window)

Related

Related posts:

1. Left Ventricular False Tendons: Anatomic, Echocardiographic, and Pathophysiologic Insights
2. Comprehensive Analysis of Left Ventricular Geometry and Function by Three-Dimensional Echocardiography in Healthy Adults
3. Assessment of Intraventricular Time Differences in Healthy Children Using Two-Dimensional Speckle-Tracking Echocardiography
4. Two Years in Review

Stay updated, free articles. Join our Telegram channel

Join