Tricuspid cleft or tetracuspid valve? Usefulness of three-dimensional echocardiogram in the assessment of isolated tricuspid regurgitation in pediatrics.

Tricuspid regurgitation (TR) in children may be secondary to congenital anomalies of the tricuspid valve complex which is composed by annulus, leaflets, commissures, chordae tendineae, and papillary muscles. The most common congenital cause is Ebstein's anomaly; however, there are less frequent causes such as abnormal number of tricuspid leaflets, tricuspid cleft, leaflet prolapse, double orifice tricuspid valve, and congenital tricuspid valve dysplasia. Identifying the precise cause is important to plan an appropriate repair surgery. In this article, the case of a 4-year-old patient with a tetracuspid valve with significant tricuspid regurgitation is presented and the morphological analysis was made by two-dimensional (2D) and three-dimensional (3D) transthoracic echocardiography. The morphological differences between a tetracuspid valve and a cleft of the anterior leaflet tricuspid valve are exposed. 3D echocardiographic evaluation of the tricuspid valve allowed a better understanding of the tricuspid valve anatomy, which includes evaluation of the tricuspid annulus, leaflets, commissures, and subvalvular apparatus. Recognizing the accurate cause of isolated tricuspid regurgitation allows better planning of the surgical technique.

Risk assessment in PAH using quantitative CMR tricuspid regurgitation: relation to heart catheterization.

AIMS: Improved risk stratification is of value for decision making in pulmonary arterial hypertension (PAH). Right heart catheterization combined with quantitative tricuspid regurgitation (TR) by cardiovascular magnetic resonance (CMR) may provide this. The aims were to study: (i) to what extent quantitative TR is associated with event-free survival; (ii) how quantitative TR is related to known prognostic markers in PAH; and (iii) to what extent quantitative TR and right atrial pressure determine right atrial dilation. METHODS AND RESULTS: Fifty patients (63 ± 17 years) with PAH referred for CMR were included. Volumes and pulmonary artery flow by CMR and pressure and vascular resistance by right heart catheterization were obtained. Composite outcome was lung transplantation or death. Four transplantations and 27 deaths occurred over a median of 2.7 years. A trend towards higher hazard ratio was shown for TR volume (TRV; 2.1, 95% CI 1.0-4.4) and TR fraction (TR%; 1.6, 95% CI 0.8-3.3) above median. TRV and TR% correlated with right ventricular (RV) end-diastolic (TRV r = 0.50; TR% r = 0.39) and end-systolic (TRV r = 0.35; TR% r = 0.30) volumes, pulmonary vascular resistance (TRV r = 0.28; TR% r = 0.43), N terminal pro brain natriuretic peptide (TRV r = 0.65; TR% r = 0.68), cardiac index (TRV r = -0.32; TR% r = -0.54), pulmonary artery stroke volume (TRV r = -0.32; TR% r = -0.58) and effective RV ejection fraction by pulmonary artery quantitative flow (TRV r = -0.56; TR% r = -0.69), but not RVEF. Both TR% and right atrial pressure determined right atrial volumes (r2  = 0.38; r2  = 0.48). CONCLUSIONS: A clear trend towards worse outcome with larger TRV or TR% was shown; however, the number of events was insufficient for significant outcome differences. Prognostic value of quantitative TR should be investigated in a larger multicentre cohort. Effective RV ejection fraction may be considered an improved measure of RV function in PAH.

Acute In Vivo Functional Assessment of a Biodegradable Stentless Elastomeric Tricuspid Valve.

Degradable heart valves based on in situ tissue regeneration have been proposed as potentially durable and non-thrombogenic prosthetic alternatives. We evaluated the acute in vivo function, microstructure, mechanics, and thromboresistance of a stentless biodegradable tissue-engineered heart valve (TEHV) in the tricuspid position. Biomimetic stentless tricuspid valves were fabricated with poly(carbonate urethane)urea (PCUU) by double-component deposition (DCD) processing to mimic native valve mechanics and geometry. Five swine then underwent 24-h TEHV implantation in the tricuspid position. Echocardiography demonstrated good leaflet motion and no prolapse and trace to mild regurgitation in all but one animal. Histology revealed patches of proteinaceous deposits with no cellular uptake. SEM demonstrated retained scaffold microarchitecture with proteinaceous deposits but no platelet aggregation or thrombosis. Explanted PCUU leaflet thickness and mechanical anisotropy were comparable with native tricuspid leaflets. Bioinspired, elastomeric, stentless TEHVs fabricated by DCD were readily implantable and demonstrated good acute function in the tricuspid position.

Multimodality Imaging of the Tricuspid Valve for Assessment and Guidance of Transcatheter Repair.

The tricuspid valve is a highly complex structure, with variability in the number of leaflets and scallops. The mechanism of regurgitation is multifactorial in etiology, a mix of functional and degenerative tricuspid regurgitation. Iatrogenic tricuspid regurgitation is becoming more common secondary to pacemaker wire impingement of leaflet function and coaptation. Echocardiographic imaging of the tricuspid valve is particularly challenging given its anatomic location and other interfering structures, including pacemaker wires. Preprocedural planning and intraprocedural guidance for transcatheter intervention relies on a comprehensive understanding of tricuspid anatomy and the use of 3-dimensional transesophageal echocardiography. The incorporation of computed tomography and cardiac magnetic resonance imaging likely will provide increasing accuracy and optimization of procedural success.

Significant Drop in Right Atrial Pressure Does Not Influence Fractional Flow Reserve Coronary Assessment.

The effect of a highly elevated level of right atrial filling pressure on fractional flow reserve (FFR) measurement remains unclear. Transcatheter tricuspid valve intervention, a recently introduced option for inoperable or high-risk patients, represents a unique model of in-vivo physiology to investigate the eventual influence of central venous pressure on coronary FFR measurements. The case is reported of a patient with a degenerated tricuspid surgical bioprosthesis who underwent transcatheter tricuspid valve-in-valve replacement and concomitant coronary functional assessment with FFR. In an experimental model, the significant fall in right atrial pressure did not influence FFR measurements in the presence of angiographically proven mild coronary artery disease.

Decreased tricuspid regurgitation following percutaneous closure of congenital perimembranous ventricular septal defect: immediate and 6-month echocardiographic assessment.

As a common concomitant performance and the most frequent complications of transcatheter perimembranous ventricular septal defect (VSD) closure, tricuspid regurgitation (TR) has rarely been concerned. From January 2008 to December 2012, a total of 70 patients (men: 33, women: 37; mean age: 30.0 ± 17.1 years) with at least mild TR before VSD closure were examined in 508 consecutive congenital perimembranous VSD patients to investigate the outcomes of TR. After VSD closure, the jet area decreased from 3.4 ± 2.5 to 1.2 ± 2.5 cm(2) (p < 0.001); however, no significant decrease was found in 3 patients (mean age 59.7 ± 2.5 years) with severe TR (12.0 ± 1.2 versus 11.2 ± 3.2 cm(2), p = 0.668). Compared to the early outcome after VSD closure, the jet area detected by TTE at 6-month follow-up had further decreased (1.2 ± 2.5 versus 0.9 ± 2.2 cm(2), p < 0.001). In 6 patients, a slight residual shunt was detected immediately after VSD closure and diminished in 3 patients at 6-month follow-up. The hemolysis occurred in one of these six patients and recovered after 3 days. In conclusion, functional TR was ameliorated after percutaneous VSD closure, although persistent abundant TR was common in patients with severe TR before procedure.

Non-invasive assessment of cardiac function and pulmonary vascular resistance in an canine model of acute thromboembolic pulmonary hypertension using 4D flow cardiovascular magnetic resonance.

BACKGROUND: The purpose of this study was to quantify right (RV) and left (LV) ventricular function, pulmonary artery flow (QP), tricuspid valve regurgitation velocity (TRV), and aorta flow (QS) from a single 4D flow cardiovascular magnetic resonance (CMR) (time-resolved three-directionally motion encoded CMR) sequence in a canine model of acute thromboembolic pulmonary hypertension (PH). METHODS: Acute PH was induced in six female beagles by microbead injection into the right atrium. Pulmonary arterial (PAP) and pulmonary capillary wedge (PCWP) pressures and cardiac output (CO) were measured by right heart catheterization (RHC) at baseline and following induction of acute PH. Pulmonary vascular resistance (PVRRHC) was calculated from RHC values of PAP, PCWP and CO (PVRRHC = (PAP-PCWP)/CO). Cardiac magnetic resonance (CMR) was performed on a 3 T scanner at baseline and following induction of acute PH. RV and LV end-diastolic (EDV) and end-systolic (ESV) volumes were determined from both CINE balanced steady-state free precession (bSSFP) and 4D flow CMR magnitude images. QP, TRV, and QS were determined from manually placed cutplanes in the 4D flow CMR flow-sensitive images in the main (MPA), right (RPA), and left (LPA) pulmonary arteries, the tricuspid valve (TRV), and aorta respectively. MPA, RPA, and LPA flow was also measured using two-dimensional flow-sensitive (2D flow) CMR. RESULTS: Biases between 4D flow CMR and bSSFP were 0.8 mL and 1.6 mL for RV EDV and RV ESV, respectively, and 0.8 mL and 4 mL for LV EDV and LV ESV, respectively. Flow in the MPA, RPA, and LPA did not change after induction of acute PAH (p = 0.42-0.81). MPA, RPA, and LPA flow determined with 4D flow CMR was significantly lower than with 2D flow (p < 0.05). The correlation between QP/TRV and PVRRHC was 0.95. The average QP/QS was 0.96 ± 0.11. CONCLUSIONS: Using both magnitude and flow-sensitive data from a single 4D flow CMR acquisition permits simultaneous quantification of cardiac function and cardiopulmonary hemodynamic parameters important in the assessment of PH.

Assessment of functional tricuspid regurgitation using 320-detector-row multislice computed tomography: risk factor analysis for recurrent regurgitation after tricuspid annuloplasty.

OBJECTIVE: Functional tricuspid regurgitation (TR) often develops secondary to left heart disease. Tricuspid annuloplasty (TAP) is usually the treatment of choice for significant TRs, but recurrence of TR after surgery can occur. Previous studies have not clearly demonstrated the cause of the recurrent TR after TAP. By using an electrocardiogram-gated 320-detector-row multislice computed tomography (CT), we sought to delineate the morphologic cause of the incompetent tricuspid valve and identify the risk factors for recurrent TR. METHODS: From August 2010 to September 2011, 35 patients underwent preoperative CT of the tricuspid valve. The distance between each commissure, the tethering angle of each leaflet, and the tethering height were measured. TAP using a rigid annuloplasty ring was performed in 22 patients. Risk factors for recurrent TR were determined by multivariate analyses. RESULTS: End-diastolic and end-systolic tricuspid valve annular diameters (TVAD) correlated significantly with preoperative TR severity (R(2), 0.2734-0.4287; P < .05). However, compared with TVAD, tethering angles and height showed stronger correlation with preoperative TR severity (R(2): tethering angles, 0.5769-0.6810; tethering height, 0.6854). Multivariate analysis revealed that tethering height was an independent risk factor of postoperative recurrent TR (P = .0069). CONCLUSIONS: TVAD, tethering angles, and tethering height correlated significantly with preoperative TR severity. The tethering height of the tricuspid valve showed significant correlation with recurrent TR.

Assessment of functional tricuspid regurgitation.

Functional tricuspid regurgitation (FTR) is characterized by structurally normal leaflets and is due to the deformation of the valvulo-ventricular complex. While mild FTR is frequent and usually benign, patients with severe FTR may develop progressive ventricular dysfunction and incur increased mortality. Therefore, FTR should not be ignored, should be appropriately diagnosed and quantified by Doppler echocardiography, and should be evaluated for corrective surgical procedures. At present, referral for surgical correction of FTR is often delayed until patients develop intractable heart failure. However, this strategy frequently translates in poor clinical outcome characterized by notable operative mortality and reduced long-term survival. Appropriate patient selection and proper timing for tricuspid valve (TV) repair or replacement are crucial for optimal outcome, but objective criteria for clinical decison-making remain poorly defined. In the present paper, we review the anatomy of the normal TV, the pathophysiology of FTR, the assessment of its severity and functional significance, and propose an algorithm for selecting patients for surgical treatment.

Understanding right ventricular dysfunction and functional tricuspid regurgitation accompanying mitral valve disease.

OBJECTIVES: The study objective was to correlate the degree of tricuspid regurgitation with clinical indicators of right-sided heart failure and both qualitative and quantitative measures of right-sided heart morphology and function in patients with degenerative mitral valve disease. METHODS: From 2001 to 2007, 1833 patients with degenerative mitral valve disease, structurally normal tricuspid valve, and no coronary artery disease underwent surgery. Right-sided heart morphology (right ventricular base-to-apex length, tethering distance and area, and right atrial systolic area) and right ventricular function (tricuspid annular plane systolic excursion, myocardial performance index, and tricuspid valve annular shortening) were measured on preoperative transthoracic echocardiograms for 100 randomly selected patients from each of tricuspid regurgitation grades 0, 1+, and 2+, and for all 93 patients with tricuspid regurgitation grade 3+/4+. Multivariable regression was used to evaluate the association of left- and right-sided heart morphology and function with tricuspid regurgitation. RESULTS: Increasing tricuspid regurgitation grade was associated with higher right ventricular pressure (P < .0001), increased tethering distance (P = .008), larger right atrial size (P = .0002), and worsening right ventricular function, particularly when 3+/4+ tricuspid regurgitation was present. When tricuspid regurgitation was 3+/4+, both tricuspid annular plane systolic excursion and myocardial performance index were almost certainly abnormal. Changes in right-sided heart morphology and right ventricular dysfunction were synergistic in relation to severity of tricuspid regurgitation. CONCLUSIONS: Functional tricuspid regurgitation accompanying mitral valve disease is associated with proportional changes in right-sided heart morphology; however, severe tricuspid regurgitation is nearly always associated with right ventricular dysfunction, suggesting a synergistic relationship. Right ventricular dysfunction is likely as important as tricuspid regurgitation because it offers an explanation for the negative prognostic impact of tricuspid regurgitation and has implications for the clinical management of patients.

Review of the role of cardiovascular magnetic resonance in congenital heart disease, with a focus on right ventricle assessment.

Adult patients with congenital heart disease (ACHD) represent a growing population due to progress in management. Surgical procedures generally fall short of restoring entirely normal anatomical and functional relations. Further procedures can be needed and lifelong follow-up is required. The right ventricle (RV) plays an important role in congenital heart disease and cardiac magnetic resonance (CMR) imaging has become the imaging method of choice for its assessment. CMR can provide relatively accurate measurements of RV volume and function, and arterial flow, with additional anatomical information provided by three-dimensional contrast angiography and late gadolinium imaging of fibrosis. Here we focus our review on three categories of ACHD in which evaluation of the RV is important: repaired tetralogy of Fallot, the systemic RV and Ebstein anomaly. We demonstrate how CMR contributes to decision-making regarding the types and timings of interventions. A dedicated CMR service should be regarded as a necessary facility of a centre specializing in the care of ACHD patients.

Live/real time three-dimensional transthoracic echocardiographic assessment of the involvement of cardiac valves and chambers in carcinoid disease.

We present an adult with metastatic carcinoid disease affecting the heart, in whom live/real time three-dimensional transthoracic echocardiography (3DTTE) provided incremental value over two-dimensional transthoracic echocardiography (2DTTE). Initial 2DTTE was able to demonstrate severe pulmonic and tricuspid regurgitation, but was unable to visualize the posterior leaflet of the tricuspid valve or the right (right anterior) leaflet of the pulmonic valve. Further analysis with 3DTTE demonstrated thickening, restricted mobility, and noncoaptation of all three leaflets of both the tricuspid and the pulmonary valves. En face viewing of tricuspid and pulmonary regurgitation vena contractas permitted more reliable quantification of regurgitation severity. In addition, localized, linear, echogenic areas consistent with carcinoid deposits were noted along the inner walls of the right atrium, atrial septum, and inferior vena cava. To the best of our knowledge, endocardial carcinoid deposits have never been reported by 2D or 3D echocardiography. En face viewing of these deposits by 3DTTE enabled measurement of their dimensions and areas. Subcostal examination also identified large circumscribed hepatic lesions consistent with metastatic disease. Neither the carcinoid deposits nor the metastatic lesions were detected by 2DTTE. This case demonstrates the usefulness of 3DTTE as a supplement to 2DTTE in more comprehensively assessing carcinoid involvement of the heart.

Echocardiographic assessment and clinical management of tricuspid regurgitation.

The evaluation and management of tricuspid regurgitation (TR) are often challenging. Significant TR is an independent predictor of reduced event-free and overall survival. Therefore, an evidence-based approach to the diagnosis and treatment of TR is of critical importance. TR can be classified into two basic categories: primary and secondary TR. The former refers to conditions in which the primary pathophysiologic process affects the valve itself, whereas the latter is much more common and occurs due to tricuspid annular dilatation, right heart failure, and/or pulmonary hypertension. Two- and three-dimensional echocardiography allow for a comprehensive assessment of TR severity and mechanisms. In patients with fixed pulmonary hypertension and right ventricular dysfunction, medical management of TR is generally preferable. In patients undergoing mitral valve surgery, tricuspid annular dilatation should trigger prophylactic tricuspid valve repair, regardless of the degree of TR. Future efforts in TR management will include development of percutaneous repair procedures.

European Association of Echocardiography recommendations for the assessment of valvular regurgitation. Part 2: mitral and tricuspid regurgitation (native valve disease).

Mitral and tricuspid are increasingly prevalent. Doppler echocardiography not only detects the presence of regurgitation but also permits to understand mechanisms of regurgitation, quantification of its severity and repercussions. The present document aims to provide standards for the assessment of mitral and tricuspid regurgitation.

Usefulness of NT-proBNP in assessment of right ventricular function in children after tetralogy of Fallot correction - a preliminary study.

BACKGROUND: Although surgical treatment for tetralogy of Fallot (TOF) has been used with considerable success, right ventricular function may remain altered after repair. The NT-proBNP assessment has been shown to be a reliable parameter for the heart failure assessment. AIM: To determine NT-proBNP values in assessment of right ventricular function in children after TOF correction. METHODS: In 20 patients after TOF correction aged from 10 to 17 years (follow-up period ranged from 7 to 16 years) NT-proBNP level at rest and after exertion, treadmill test and echocardiography were performed. In the control healthy children NT-proBNP level at rest was assessed. RESULTS: The mean values of NT-proBNP level in the TOF patients were significantly higher than in controls (11.0 +/- 12.0 fmol/l and 5.4 +/- 7.5 fmol/l, p < 0.05). In patients repaired with a transannular patch the mean value of NT-proBNP level was higher than in children operated on without a transannular patch (18.3 +/- 16.5 vs. 6.8 +/- 7.9 fmol/l, p < 0.05). In children in whom physiological shortening of QRS complex during treadmill test was observed, NT-proBNP level was lower (mean values at rest 5.0 +/- 4.8 fmol/l and after exertion 7.3 +/- 6.3 fmol/l) compared to patients with prolongation of QRS duration (mean values at rest 17.7 +/- 15.6 fmol/l and after exertion 20.3 +/- 17.8 fmol/l) (p < 0.05). Significant differences in NT-proBNP levels between children with severe pulmonary regurgitation and mild/moderate pulmonary regurgitation were detected (mean values at rest 18.6 +/- 15.0 vs. 4.2 +/- 3.9 fmol/l and after exertion 20.0 +/- 18.6 vs. 5.7 +/- 4.6 fmol/l) (p < 0.05). The NT-proBNP levels were also higher in children with severe tricuspid valve insufficiency compared to children with mild/moderate tricuspid valve regurgitation (mean values at rest 19.5 +/- 15.0 vs. 4.9 +/- 3.7 fmol/l and after exertion 22.5 +/- 17.1 vs. 7.0 +/- 4.6 fmol/l). CONCLUSIONS: The NT-proBNP level in patients after TOF correction is higher than in healthy children. The NT-proBNP level is higher and exertion tolerance is lower in children repaired with rather than without transannular patch. In patients with severe pulmonary regurgitation and/or severe tricuspid valve insufficiency NT-proBNP level is higher than in patients without right ventricular volume overload. The measurement of NT-proBNP level might be helpful in order to separate those patients after TOF correction who are at increased risk of heart failure and arrhythmia.

Tricuspid regurgitation in mitral valve disease incidence, prognostic implications, mechanism, and management.

Tricuspid regurgitation (TR) in patients with mitral valve (MV) disease is associated with poor outcome and predicts poor survival, heart failure, and reduced functional capacity. It is common if left untreated after MV replacement mainly in rheumatic patients, but it is also common in patients with ischemic mitral regurgitation. It is less common, however, in those with degenerative mitral regurgitation. It might appear many years after surgery and might not resolve after correcting the MV lesion. Late TR might be caused by prosthetic valve dysfunction, left heart disease, right ventricular (RV) dysfunction and dilation, persistent pulmonary hypertension, chronic atrial fibrillation, or by organic (mainly rheumatic) tricuspid valve disease. Most commonly, late TR is functional and isolated, secondary to tricuspid annular dilation. Outcome of isolated tricuspid valve surgery is poor, because RV dysfunction has already occurred at that point in many patients. MV surgery or balloon valvotomy should be performed before RV dysfunction, severe TR, or advanced heart failure has occurred. Tricuspid annuloplasty with a ring should be performed at the initial MV surgery, and the tricuspid annulus diameter (>or=3.5 cm) is the best criterion for performing the annuloplasty. In this article we will review the current data available for understanding the prognostic implications, mechanism, and management of TR in patients with MV disease.

Virtual reality 3D echocardiography in the assessment of tricuspid valve function after surgical closure of ventricular septal defect.

BACKGROUND: This study was done to investigate the potential additional role of virtual reality, using three-dimensional (3D) echocardiographic holograms, in the postoperative assessment of tricuspid valve function after surgical closure of ventricular septal defect (VSD). METHODS: 12 data sets from intraoperative epicardial echocardiographic studies in 5 operations (patient age at operation 3 weeks to 4 years and bodyweight at operation 3.8 to 17.2 kg) after surgical closure of VSD were included in the study. The data sets were analysed as two-dimensional (2D) images on the screen of the ultrasound system as well as holograms in an I-space virtual reality (VR) system. The 2D images were assessed for tricuspid valve function. In the I-Space, a 6 degrees-of-freedom controller was used to create the necessary projectory positions and cutting planes in the hologram. The holograms were used for additional assessment of tricuspid valve leaflet mobility. RESULTS: All data sets could be used for 2D as well as holographic analysis. In all data sets the area of interest could be identified. The 2D analysis showed no tricuspid valve stenosis or regurgitation. Leaflet mobility was considered normal. In the virtual reality of the I-Space, all data sets allowed to assess the tricuspid leaflet level in a single holographic representation. In 3 holograms the septal leaflet showed restricted mobility that was not appreciated in the 2D echocardiogram. In 4 data sets the posterior leaflet and the tricuspid papillary apparatus were not completely included. CONCLUSION: This report shows that dynamic holographic imaging of intraoperative postoperative echocardiographic data regarding tricuspid valve function after VSD closure is feasible. Holographic analysis allows for additional tricuspid valve leaflet mobility analysis. The large size of the probe, in relation to small size of the patient, may preclude a complete data set. At the moment the requirement of an I-Space VR system limits the applicability in virtual reality 3D echocardiography in clinical practice.

Live three-dimensional transthoracic echocardiographic assessment of anomalous origin of left coronary artery from the pulmonary artery.

We describe live three-dimensional transthoracic echocardiographic (3DTTE) findings in a 52-year-old female who had previously undergone an aortopulmonary tunnel operation for anomalous origin of the left coronary artery (ACA) from the pulmonary artery. Three-dimensional transthoracic echocardiography clearly delineated the origin of the ACA from the posterolateral aspect of the main pulmonary artery just above the pulmonary valve, the surgically created tunnel, as well as a small defect in the tunnel near the aortic end communicating with the pulmonary artery.

Serial noninvasive assessment of progressive pulmonary hypertension in a rat model.

Current methods used to investigate pulmonary hypertension in rat models of the disease allow for only one to two measurements of pulmonary artery (PA) pressure in the life of a rat. We investigated whether transthoracic echocardiography can be used to assess the progression of pulmonary hypertension in rats at multiple time points. Serial echocardiographic measurements were performed over a 6-wk period on rats injected with monocrotaline (MCT) or placebo. Development of a midsystolic notch in the PA waveform, a decrease in the PA flow acceleration time (PAAT), an increase in right ventricular (RV) free-wall thickness, and the development of tricuspid regurgitation (TR) were observed as pulmonary hypertension developed. Changes in the PA waveform and PAAT began in week 3 of disease development as the PA systolic pressure (PASP) reached 25-30 mmHg according to right heart catheterization. The RV free-wall thickness increased significantly by week 5 (PASPs 40-50 mmHg). Development of quantifiable TR occurred in week 6 or at PASPs > 65 mmHg. A linear correlation was found between the PAAT and PASP in the range of 30-65 mmHg and between the RV-right atrial pressure gradient (derived from TR velocity) and PASP at pressures >65 mmHg, which enabled a noninvasive estimate of the PASP over a wide range of pressures based on these parameters. These data indicate that transthoracic echocardiography can be used for monitoring the progress of pulmonary hypertension in a rat model.