Right Ventricular Outflow Tract Reintervention in the Transcatheter Era: Outcomes and Cost Analysis.

Surgical pulmonary valve insertion (SPVI) for re-entry right ventricular outflow tract intervention (RVOTI) remains an established and reproducible approach. Fast-track in patients undergoing RVOTI of the comprehensive valve program targets early ICU and hospital discharge (Hd). Feasibility study for outcome and cost analysis was undertaken. Between January 2015 and December 2016, 34 patients underwent re-entry RVOTI. Seventeen had SPVI and 17 transcatheter PVI (TPVI). Surgical perioperative fast-track protocol was used. Echocardiographic evaluation preoperatively (TTE-1), after RVOTI (TTE-2), at hospital discharge (TTE-3), and follow-up (TTE-4) were obtained. Cost Analysis included procedural and hospital costs. Mean follow-up period was 11.3 ± 6.9 months. All patients were extubated prior to ICU arrival. Mean age was 8.5 ± 7.8 for SPVI [vs 28.5 ± 8.6 years for TPVI] (p < 0.05). There was no hospital mortality or 30-day readmission for SPVI (versus 1 for TPVI).Mean hospital length of stay (LOS) was 4.1 ± 1.1 days for SPVI [vs 1.1 ± 0.7 days for TPVI] (p < 0.05). Number of prior sternal re-entry had no influence on outcome. RV systolic pressure referenced to LVSP (rRVSP, %) and diastolic dimension (RVEDDi, z score) showed sustainable improvement (TTE-2, TTE-3, TTE-4) in both groups compared to TTE-1 (p < 0.05). Mean total hospital cost was $5475.86 ± 2503.91 lower after SPVI (p = 0.09), 21.7% procedural cost reduction. Patients undergoing RVOTI can be safely stratified, based on a customized concept, towards SPVI or TPVI. Standardized strategy can advocate a fast-track path. SPVI is associated with comparable mid-term outcomes to TPVI although SPVI is delivered in younger patients. Despite longer LOS SPVI is associated with reduced hospital cost. Multisite studies might help determine suitability for each strategy on cost containment/quality of life basis.

Novel Multiphase Assessment for Predicting Left Ventricular Outflow Tract Obstruction Before Transcatheter Mitral Valve Replacement.

OBJECTIVES: This study proposes a physiologic assessment of left ventricular outflow tract obstruction (LVOTO) that accommodates changes in systolic flow and accounts for the dynamic neo-left ventricular outflow tract (LVOT). BACKGROUND: Patients considered for transcatheter mitral valve replacement trials often screen-fail because of the perceived risk of LVOTO. In the Intrepid Global Pilot Study, assumed risk of LVOTO was based on computed tomography estimates of the neo-LVOT area computed at end-systole. However, this may overestimate actual risk. METHODS: Retrospective analyses were performed for screen-failed patients for potential LVOTO (n = 33) and treated patients (n = 29) with available dynamic computed tomography. A multiphase assessment of the neo-LVOT area was performed and represented as: 1) multiphase average; and 2) early systolic value. Prospective evaluation was performed in 9 patients approved for enrollment with multiphase and early systole methods that would have previously screen-failed with the end-systolic approach. RESULTS: Of 166 patients screened for possible inclusion; 32 were screen-failed for nonanatomical reasons. Screen failure for assumed LVOTO risk occurred in 37 of 134 (27.6%) patients. Retrospective analysis indicated a potential enrollment increase of 11 of 33 (33.3%) and 18 of 33 (54.5%) patients using multiphase and early systolic assessment methods. In the prospective cohort, there were no clinical observations of LVOTO 30 days post-procedure, despite assumed risk based on end-systolic estimates. CONCLUSIONS: Multiphase, and specifically early systolic, assessment of the neo-LVOT may better determine risk of LVOTO with transcatheter mitral valve replacement compared with end-systolic estimates. This novel approach has the potential to significantly increase patient eligibility, with over one-half of patients previously screen-failed now eligible for treatment.

Assessment of left ventricular outflow tract and aortic root: comparison of 2D and 3D transthoracic echocardiography with multidetector computed tomography.

AIMS: Accurate echocardiographic assessment of left ventricular outflow tract (LVOT) and the aortic root is necessary for risk stratification and choice of appropriate treatment in patients with pathologies of the aortic valve and aortic root. Conventional 2D transthoracic echocardiographic (TTE) assessment is based on the assumption of a circular shaped LVOT and aortic root, although previous studies have indicated a more ellipsoid shape. 3D TTE and multidetector computed tomography (MDCT) applies planimetry and are not dependent on geometrical assumptions. The aim was to test accuracy, feasibility, and reproducibility of 3D TTE compared to 2D TTE assessment of LVOT and aortic root areas, with MDCT as reference. METHODS AND RESULTS: We examined 51 patients with 2D/3D TTE and MDCT at the same day. All patients were re-examined with 2D/3D TTE on a different day to evaluate 2D and 3D re-test variability. Areas of LVOT, aortic annulus, and sinus were assessed using 2D, 3D TTE, and MDCT. Both 2D/3D TTE underestimated the areas compared to MDCT; however, 3D TTE areas were significantly closer to MDCT-areas. 2D vs. 3D mean MDCT-differences: LVOT 1.61 vs. 1.15 cm2, P = 0.019; aortic annulus 1.96 vs. 1.06 cm2, P < 0.001; aortic sinus 1.66 vs. 1.08 cm2, P = 0.015. Feasibility was 3D 76-79% and 2D 88-90%. LVOT and aortic annulus areas by 3D TTE had lowest variabilities; intraobserver coefficient of variation (CV) 9%, re-test variation CV 18-20%. CONCLUSION: Estimation of LVOT and aortic root areas using 3D TTE is feasible, more precise and more accurate than 2D TTE.

Percutaneous Versus Surgical Pulmonic Valve Implantation for Right Ventricular Outflow Tract Dysfunction.

BACKGROUND/PURPOSE: Percutaneous pulmonic valve implantation (PPVI) is an alternative treatment strategy to surgical pulmonic valve implantation (SPVI) for right ventricular outflow tract (RVOT) dysfunction. This study sought to compare outcomes of both treatment strategies. METHODS: The study population was extracted from the 2014 Nationwide Readmissions Database (NRD) using International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes for PPVI and SPVI. Study outcomes included all-cause in-hospital mortality, length of index hospital stay (LOS), post-procedural bleeding, mechanical complications of heart valve prosthesis, vascular complications (VC), infective endocarditis (IE), total hospitalization charges, and 30-day readmission rates. RESULTS: A total of 975 patient discharges (176 in PPVI and 799 in SPVI group) were identified (average age 25.7 years; 57.5% male). PPVI was associated with significantly shorter median LOS (1 versus 5 days, p < 0.01), lower risk of bleeding (4.6% versus 26.4%, p < 0.01), and lower total hospitalization charges ($169,551.7 versus $210,681.8, p = 0.02). There was no significant difference between both groups in terms of all-cause in-hospital mortality (0% versus 1.4%, p = 0.12), mechanical complications of heart valve prosthesis (1.7% versus 2.0%, p = 0.78), VC (2.3% versus 2.0%, p = 0.82), IE (1.7% versus 3.1%, p = 0.31), or 30-day readmission rates (4.4% versus 7.6%, p = 0.16). CONCLUSION: Compared with SPVI, PPVI was associated with shorter LOS, lower bleeding, and lower total charges. There was no significant difference between the two strategies in terms of all-cause in-hospital mortality, mechanical complications of heart valve prosthesis, VC, IE, or 30-day readmission rates.

Toward the integration of global longitudinal strain analysis in the assessment of neonatal aortic coarctation? A preliminary study.

BACKGROUND: Coarctation of the aorta (CoA) is still challenging to diagnose in neonates with patent ductus arteriosus (PDA). Speckle tracking echocardiography allows reliable analysis of myocardial deformation in newborns and seems to provide important insides into regional changes in patients with left ventricular (LV) outflow tract obstruction. AIMS: To assess the interest of LV global longitudinal strain (GLS) measurement for predicting CoA in neonates with PDA and prenatal suspicion. METHODS: Prospective single-center study. Twenty-two newborns with prenatal suspicion of CoA were included. All newborns were evaluated in the first 12 hours of life. To assess the feasibility and the reproducibility of GLS, 14 healthy full-term newborns with PDA (group 3) were screened. CoA was diagnosed when DA closed, according to usual echocardiographic criteria. RESULTS: Six neonates developed CoA after DA closure (group 1) whereas 16 did not (group 2). Mean gestational age and birth weight were not different between the groups. GLS measurements were possible in 100%. Intra- and inter-observer variability of strain measurements was acceptable. GLS values were significantly lower in neonates who developed CoA (P=0.015). To predict CoA, cut-off value of -17.42% gave the best compromise for sensitivity (83%) and specificity (72%). Aortic arch dimensions were modestly correlated with strain values. The presence of a bicuspid aortic valve was not associated with significant lower GLS values. CONCLUSION: LV GLS analysis is a feasible and reproducible echocardiographic technique in newborns with PDA. Newborns who will develop CoA seem to have lower values of GLS than healthy neonates. Further studies are needed to confirm these preliminary results.

Reliability of Peak Exercise Stroke Volume Assessment by Impedance Cardiography in Patients with Residual Right Outflow Tract Lesions After Congenital Heart Disease Repair.

Global ventricular response to exercise may be useful in follow-up of patients with residual right outflow tract lesions after congenital heart disease repair. In this context, impedance cardiography is considered accurate for stroke volume (SV) measurement during exercise testing, however, to date, only partial assessment of its reliability has been reported. We retrospectively evaluated relative and absolute reliability of peak SV by impedance cardiography during exercise using intraclass correlation (ICC) and standard error of measurement (SEM) in this population. Peak SV was measured in 30 young patients (mean age 14.4 years ± 2.1) with right ventricular outflow tract reconstruction who underwent two cardiopulmonary exercise tests at a mean one-year interval. SV was measured using a signal morphology impedance cardiography analysis device (PhysioFlow®) and was indexed to body surface area. ICC of peak indexed SV measurement was 0.80 and SEM was 10.5%. High heterogeneity was seen when comparing patients according to peak indexed SV; in patients with peak SV < 50 ml/m2 (15 patients), ICC rose to 0.95 and SEM dropped to 2.7%, while in patients with a peak SV > 50 ml/m2 relative and absolute reliability decreased (ICC = 0.45, SEM = 12.2%). Peak exercise SV assessment by a PhysioFlow® device represents a highly reliable method in patients with residual right outflow tract lesions after congenital heart disease repair, especially in patients with peak SV < 50 ml/m2. In this latter group, a peak SV decrease > 7.3% (corresponding to the minimum "true" difference) should be considered a clinically-relevant decrease in global ventricular performance and taken into account when deciding whether to perform residual lesion removal.

Assessment of transposition of the great arteries associated with multiple malformations using dual-source computed tomography.

PURPOSE: To determine the value of dual-source computed tomography (DSCT) in depicting the morphological characteristics and diagnosing the associated malformations for patients with transposition of the great arteries (TGA) before surgery. MATERIALS AND METHODS: Twenty-five patients with TGA who underwent DSCT and transthoracic echocardiography (TTE) examination were retrospectively reviewed. The morphological types of TGA, the spatial relationship between the pulmonary artery and the aorta, as well as coronary artery-associated abnormalities were assessed by DSCT. In contrast to TTE, the diagnostic accuracy of associated malformations on DSCT were analyzed and calculated with reference to surgical or digital subtraction angiography (DSA) findings. Effective doses (EDs) were also calculated. RESULTS: Among the 25 patients, 12 (48%) had ventricular septal defects and left ventricular outflow tract stenosis. Sixteen patients (16/25, 64%) had great arteries with an oblique spatial relationship on DSCT. In addition, we found seven patients (7/25, 28%) with coronary artery malformation, including five with an abnormal coronary origin and two with signs of a myocardial bridge. According to DSA or surgical findings, DSCT was superior to TTE in demonstrating extracardiac anomalies (sensitivity, anomalies of great vessels: 100% vs. 93.33%, other anomalies: 100% vs. 46.15%). The mean estimated ED for those aged <10 years was <2 mSv (1.59 ± 0.95 mSv). CONCLUSIONS: DSCT can achieve an overall assessment of patients with TGA, including any associated malformations as well as the identification of the spatial relationship of the great arteries. DSCT can therefore be considered as an alternative imaging modality for surgical decision making.

Dissecting functional impairment in hypertrophic cardiomyopathy by dynamic assessment of diastolic reserve and outflow obstruction: A combined cardiopulmonary-echocardiographic study.

BACKGROUND: Exercise limitation in hypertrophic cardiomyopathy (HCM) patients is often attributed to left ventricular outflow tract (LVOT) obstruction and diastolic impairment. However, these features assessed at rest fail to predict performance. To evaluate their variations and interplay during effort in HCM, we performed echocardiographic assessment of diastolic function and outflow obstruction during cardiopulmonary test (CPX). METHODS: We included 197 HCM patients (mean age 45±15years, 129 males), undergoing CPX. Diastolic dysfunction (DD) grade was measured at baseline and at peak exercise. Oxygen consumption (VO2 max) values <75% of maximum predicted were considered abnormal. RESULTS: One hundred-seven patients (54%) had DD grade II-III at rest (Rest DD), 40 (20%) showed preserved diastolic function (grade 0/I) both at rest and on effort (No DD). The remaining 50 patients (25%) had a grade 0/I pattern at rest but exhibited impaired diastolic reserve on exercise (Latent DD). Latent DD was associated with higher prevalence of patients with VO2<75% in both the non-obstructive and the latent-obstructive group: at multivariate regression analysis, left atrium volume index, LV obstruction at rest and rest or latent DD were significantly associated with lower peak VO2. Excluding rest-obstructive patients from the analysis, rest- or latent DD were the only determinants of exercise impairment (latent-obstructive, OR 8.9; 95% CI 1.5-18.8; p=0.012; non-obstructive, OR 2.2; 95% CI 1.0-5.8; p=0.03). CONCLUSION: Latent DD is a major determinant of exercise intolerance in HCM. Comprehensive assessment of outflow obstruction and diastolic reserve during cardiopulmonary test represents an important adjunct to clinical management.

Prevalence, associated factors and management implications of left ventricular outflow tract obstruction in takotsubo cardiomyopathy: a two-year, two-center experience.

BACKGROUND: Some patients with Takotsubo cardiomyopathy (TTC) develop cardiogenic shock due to left ventricular outflow tract (LVOT) obstruction - there is, however, a paucity of data regarding this condition. METHODS: Prevalence, associated factors and management implications of LVOT obstruction in TTC was explored, based on two-year data from two Belgian heart centres. RESULTS: A total of 32 patients with TTC were identified out of 3,272 patients presenting with troponin-positive acute coronary syndrome. In six patients diagnosed with TTC (19%), a significant LVOT obstruction was detected by transthoracic echocardiography. Patients with LVOT obstruction were older and had more often septal bulging, and presented more frequently in cardiogenic shock as compared to those without LVOT obstruction (P < 0.05). Moreover, all patients with LVOT obstruction showed systolic anterior motion (SAM) of the anterior mitral valve leaflet, which was associated with a higher grade of mitral regurgitation (2.2±0.7 vs. 1.0±0.6, P<0.001). Adequate therapeutic management including fluid resuscitation, cessation of inotropic therapy, intravenous ß-blocker, and the use of intra-aortic balloon pump resulted in non-inferior survival in TTC patients with LVOT obstruction as compared to those without LVOT obstruction. CONCLUSIONS: TTC is complicated by LVOT obstruction in approximately 20% of cases. Older age, septal bulging, SAM-induced mitral regurgitation and hemodynamic instability are associated with this condition. Timely and accurate diagnosis of LVOT obstruction by echocardiography is key to successful management of these TTC patients with LVOT obstruction and results in a non-inferior outcome as compared to those patients without LVOT obstruction.

Angioplasty of obstructed homograft conduits in the right ventricular outflow tract with ultra-noncompliant balloons: assessment of therapeutic efficacy and conduit tears.

BACKGROUND: Angioplasty and stent placement in right ventricle-to-pulmonary artery (RV-PA) conduits have been shown to prolong the functional lifespan of a conduit. Safety and efficacy of angioplasty of obstructed RV-PA homografts using ultra-noncompliant (UNC) or ultrahigh-pressure balloons are unknown. METHODS AND RESULTS: From 2004 to 2012, 70 patients underwent 76 procedures for angioplasty of RV-PA homografts with UNC Atlas balloons. The UNC group was compared with a partially contemporaneous control cohort of 81 patients who underwent 84 angioplasty procedures with conventional balloons. Acute hemodynamic changes after angioplasty of homografts with UNC balloons included significantly reduced RV:Ao pressure ratio (P=0.02) and right ventricular outflow tract gradients (P≤0.001). Balloon waist resolution was more frequently achieved with UNC balloons (P=0.04), and balloon rupture occurred less often (P<0.001). Conduit tears of any severity occurred in 22% of patients overall and were more common in the UNC group (P=0.001). Patients with any conduit tear had significantly greater reduction in their RV:Ao pressure ratio (P<0.001) and right ventricular outflow tract gradient (P=0.004) than those with no tear. There were 4 unconfined tears, all in the UNC group, with no acute decompensations or deaths and only 1 patient who required surgical management. CONCLUSIONS: RV-PA conduit tears are common in patients undergoing angioplasty, but clinically important tears, which only occurred during UNC angioplasty in this series, were uncommon. UNC balloons can be used to good effect with significant reduction in right ventricular outflow tract gradient and the RV:Ao ratio when compared with conventional balloons.

Bedside assessment of central venous pressure by sonographic measurement of right ventricular outflow-tract fractional shortening.

OBJECTIVES: We aimed to assess the suitability of right ventricular outflow tract (RVOT) fractional shortening for estimating low central venous pressure (CVP). To the best of our knowledge, there have been no similar studies in the English language literature. METHODS: In this cross-sectional study, the emergency physicians measured the RVOT fractional shortening on parasternal short-axis view. A receiver operating characteristic curve analysis was conducted to identify the threshold that maximized the sensitivity and specificity for discriminating normal and low CVPs by the RVOT fractional shortening value. The sensitivity, specificity, and the positive and the negative likelihood ratios of RVOT fractional shortening to truly estimate CVP were calculated. RESULTS: Fifty-eight consecutive patients had invasive CVP monitoring. Nine patients with high CVP and eight for other reasons were excluded. Forty-one patients were enrolled in the study, of whom 21 were in low CVP group and 20 were in normal CVP group. RVOT diastolic diameters, RVOT systolic diameters, and RVOT fractional shortening were lower in low CVP group and this difference was statistically significant (P<0.001). The cutoff value for RVOT fractional shortening to differentiate the low and normal CVPs using the highest sensitivity and specificity was 26.44%. Area under the receiver operating characteristic curve was 0.933 (0.810-0.987) with a P value of less than 0.001. The sensitivity and specificity of RVOT fractional shortening to truly estimate CVP were 95 (75-99) and 80% (58-94), respectively. CONCLUSION: In the hands of emergency physicians, a RVOT fractional shortening measurement is a good predictor of low CVP.

Exercise stress echocardiographic assessment of outflow tract and ventricular function in patients with an obstructed right ventricular-to-pulmonary artery conduit after repair of conotruncal heart defects.

This study assessed right ventricular (RV) and RV outflow tract (RVOT) function and pressure in response to exercise in patients with an obstructed RV-pulmonary artery (PA) conduit using exercise stress echocardiography (ESE) to evaluate these parameters. RV-PA conduits inevitably develop stenosis and/or regurgitation over time. Assessment of conduit obstruction only at rest may not reveal the extent of physiologic perturbation related to RV pressure loading. Patients with a stenotic RV-PA conduit who were being considered for transcatheter pulmonary valve placement were approached prospectively. ESE was performed and ventricular images were obtained at rest and at peak exercise. Forty patients (median age 17 years) were enrolled. Most patients had tetralogy of Fallot (63%) and were in New York Heart Association class II (59%). Exercise stress echocardiographic images were adequate in 38 patients (95%). With exercise there was a significant increase in maximum instantaneous RVOT gradient from rest (59 vs 96 mm Hg, p <0.001); exercise-induced change in RVOT gradient correlated with global RV strain at rest (r = -0.3, p = 0.05). Compared to measurements at rest there were significant increases in median peak longitudinal strain of the left ventricular free wall, interventricular septum, and global left ventricular strain at peak exercise. There were no significant changes in median RV strain at peak exercise (RV free wall -14.3 [-26, -8] at rest vs -15.2 [-27, -3] at peak exercise, p = 0.87; global RV strain -13.9 [-32, -9] vs -15.1 [-23, -6], p = 0.11). In conclusion, using ESE it was possible to evaluate abnormal ventricular function and conduit dysfunction at peak exercise in patients with an obstructed RV-PA conduit.

Assessment of left ventricular outflow gradient: hypertrophic cardiomyopathy versus aortic valvular stenosis.

OBJECTIVES: This study examined the relationship between peak-to-peak (common invasive measurement), peak instantaneous (common Doppler measurement), and mean pressure gradients in patients with hypertrophic cardiomyopathy (HCM) and aortic stenosis (AS). BACKGROUND: In patients with AS, the peak-to-peak gradient and peak instantaneous gradient are discrepant, and the mean gradient best represents obstruction severity. The pathophysiology of outflow obstruction differs in HCM, with the maximum gradient occurring in late systole, thus the optimal method for quantifying gradient severity in HCM remains undefined. METHODS: Fifty patients with HCM and 50 patients with AS underwent gradient characterization at cardiac catheterization (age 55 ± 15 years vs. 72 ± 9 years; 48% vs. 42% male, respectively). All HCM patients were studied with high-fidelity, micromanometer-tip catheters and transseptal measurement of left ventricular inflow and central aortic pressures. In AS, simultaneous left ventricular and central aortic pressures were recorded. RESULTS: The peak instantaneous gradient was linearly correlated with peak-to-peak gradient in HCM (R(2) = 0.98, p < 0.0001), with the relationship close to the line of identity. In AS, more scatter and further deviation from the line of identity occurred when comparing the peak instantaneous gradient to the peak-to-peak gradient (R(2) = 0.70, p < 0.0001). Both peak-to-peak and peak instantaneous gradients were consistently higher than the mean gradient in HCM, with wide 95% confidence limits of agreement (26.7 ± 46.5 mm Hg and 16.4 ± 47.2 mm Hg, respectively). CONCLUSIONS: In HCM, peak instantaneous and peak-to-peak gradient demonstrate excellent correlation. Consequently, both peak instantaneous and peak-to-peak gradients can be used to classify obstruction severity in HCM. By contrast, the mean gradient should direct clinical management in AS.

European Association of Echocardiography recommendations for the assessment of valvular regurgitation. Part 1: aortic and pulmonary regurgitation (native valve disease).

Valvular regurgitation represents an important cause of cardiovascular morbidity and mortality. Echocardiography has become the primary non-invasive imaging method for the evaluation of valvular regurgitation. The echocardiographic assessment of valvular regurgitation should integrate quantification of the regurgitation, assessment of the valve anatomy, and function as well as the consequences of valvular disease on cardiac chambers. In clinical practice, the management of patients with valvular regurgitation thus largely integrates the results of echocardiography. It is crucial to provide standards that aim at establishing a baseline list of measurements to be performed when assessing regurgitation.

Direct measurement of left ventricular outflow tract by transthoracic real-time 3D-echocardiography increases accuracy in assessment of aortic valve stenosis.

BACKGROUND: Evaluation of aortic valve stenosis is a major clinical application of echocardiography. The widely employed continuity equation requires determination of the left ventricular outflow tract (LVOT) area. We aimed at testing whether direct area measurement in a volume data set is superior to conventional calculation from the LVOT diameter. METHODS: We performed LVOT measurement in 20 normal subjects and 83 patients with moderate to severe aortic stenosis with a transthoracic real-time three-dimensional echocardiography (3D-TTE) technique in two systolic frames. The off-line 3D-evaluation allows full choice of section planes within the acquired volume data set. The aortic valve area was calculated from systolic LVOT areas. These results were compared to area values obtained by M-mode LVOT-diameters (area=pi(*)(d/2)(2)). In addition, the calculated aortic valve orifices were compared to invasive measurements or direct planimetry in the transthoracic or transesophageal examination. RESULTS: Two independent observers found a reduction in LVOT area during systole (p<0.001). Often a more ellipsoid-like shaped LVOT resulted at end-systole which was shown by a reduction (p<0.001) of the LVOT longitudinal to oblique axis ratio. 3D-TTE determination of aortic valve orifice areas (mean difference: -0.04+/-0.09 cm(2)) showed a lesser deviation from the invasively or planimetrically measured areas than conventionally calculated LVOT areas (mean difference: -0.1+/-0.1 cm(2)) using the continuity equation (p<0.001). CONCLUSIONS: The tested transthoracic 3D-echocardiography technique offers non-invasive measurement of the LVOT and aortic valve area based on the continuity equation during systole and thus improves accuracy and, additionally, agreement of aortic valvular area determination with invasive and direct measurements.

Canine dynamic left ventricular outflow tract obstruction: assessment of myocardial function and clinical outcome.

OBJECTIVE: The aims of this study were (i) to evaluate echocardiographic findings and myocardial function including pulsed wave tissue Doppler imaging in dogs with naturally occurring dynamic left ventricular outflow tract obstruction and (ii) to investigate the clinical outcome and response to therapy in these dogs. METHODS: Two cases were retrospectively reviewed and three cases were prospectively evaluated including clinical findings, diagnostic test results (including standard Doppler echocardiography and pulsed wave tissue Doppler imaging), response to treatment and outcome. The two retrospective cases received no treatment. Other cases were treated with a beta-blocker. RESULTS: All dogs had a variable intensity left apical systolic murmur. Concentric left ventricular hypertrophy, systolic anterior motion of the mitral valve and scimitar-shaped left ventricular outflow tract Doppler flow profile were present in all cases. Pulsed wave tissue Doppler imaging interrogation of the interventricular septum revealed E'/A' reversal in all but one patient. Regression of left ventricular hypertrophy and total resolution of the dynamic left ventricular outflow tract obstruction were observed in all cases. CLINICAL SIGNIFICANCE: Young dogs are affected with a possible terrier breed predisposition. Dynamic left ventricular outflow tract obstruction may be distinguished from canine hypertrophic cardiomyopathy as progressive resolution of echocardiographic abnormalities was documented. Pulsed wave tissue Doppler imaging abnormalities provide further evidence for significant diastolic dysfunction associated with the hypertrophy.

Transoesophageal echocardiographic assessment of obstruction to the pulmonary venous pathway in children with Mustard or Senning repair.

The morphology and mechanism of obstruction to the pulmonary venous pathway in patients following either Mustard or Senning repair of complete transposition was assessed using transoesophageal echocardiography. Seven patients underwent catheterization and complete transoesophageal study in both transverse and longitudinal planes, followed by balloon dilation of the obstructed venous pathway in five of seven under transoesophageal echocardiography guidance. A complete scan of both systemic and venous pathway was obtained in all patients. Four patients with a Mustard repair were found to have a 'tubular' baffle, with stenosis resulting from a discrete wedge of tissue arising from the atrial free wall in association with fibrous adhesions to the baffle. In the three patients with a Senning repair the intra-atrial baffle showed a characteristic 'peaked' appearance, with stenosis of the venous pathway stenosis related directly to contracture of the patch used to augment the atrial free wall. The mechanism of obstruction appears to be inherent to the different surgical techniques. Indwelling transoesophageal echocardiography provided immediate haemodynamic and morphologic assessment of the efficacy of dilation of the obstructed venous pathway.

The assessment of intramural stress alignment on the beating heart in situ using micro-ergometry: functional implications.

The main local stress transmission pathways in the left ventricular base, midportion and apex in up to seven layers have been assessed in normal dog and porcine hearts, in hypertrophied dog hearts, and in three pig hearts having undergone a temporary left ventricular outflow stricture. The rotational sensitivity of needle force probes was used to determine the focal surface-parallel direction of the myocardial tension vector. In all places investigated the orientation of the force transmission pathways differs slightly from the morphologically determined fibre alignment. Vector rotation upon an axis normal to the epicardial surface is definitely tempered as compared to fibre rotation. Alterations in the force transmission pathways assessed in hypertrophied dog hearts by micro-ergometry qualitatively confirm structural remodelling in so far as an irregularity in the transmural rotation of the main stress vector was found. The measured disparities between the alignment of the myocardial fibre weave and the direction of stress transmission both in the normal and the diseased heart is widely individual, and hence, scattering of the data is marked. However, it must also be called into consideration that the measured orientation of force vectors is that at the moment of highest developed force, only. Further investigations will elucidate if discrepancies between that force vector and morphology are less pronounced when the vector is averaged over the entire heart cycle.