Assessment of left ventricular outflow in hypertrophic cardiomyopathy using anyplane and paraplane analysis of three-dimensional echocardiography

Association Between Three-Dimensional Left Ventricular Outflow Tract Area and Gradients After Myectomy in Hypertrophic Obstructive Cardiomyopathy

OBJECTIVE

Determine whether the intraoperative three-dimensional left ventricular outflow tract cross-sectional area may be inversely correlated with pressure gradients as a determinant of surgical success after septal myectomy in hypertrophic cardiomyopathy patients.

DESIGN

Perioperative data were obtained by retrospective review.

SETTING

Toronto General Hospital, University of Toronto, Toronto, Canada, a tertiary hospital.

PARTICIPANTS

The study comprised 67 patients with hypertrophic obstructive cardiomyopathy.

INTERVENTIONS

Transthoracic and intraoperative transesophageal echocardiographic assessment of pressure gradients. Transesophageal measurement of the three-dimensional left ventricular outflow tract cross-sectional area.

MEASUREMENTS AND MAIN RESULTS

The smallest left ventricular outflow tract area increased on average 1.883 cm² (98.3%) after septal myectomy. There was a significant correlation between the increase in the area and the transesophageal pressure gradients (r = -0.32; p = 0.01) after myectomy, but none with postoperative transthoracic gradients at rest (r = -0.10; p = 0.42). Postoperative transesophageal and transthoracic gradients were significantly correlated (r = 0.26; p = 0.04). The best risk factors to predict high residual gradients were preoperative transesophageal gradient >97 mmHg, postoperative transesophageal area <3.16 cm², and moderate or more residual transesophageal mitral regurgitation (specificity 89%, 81%, and 78%, respectively).

CONCLUSIONS

Three-dimensional left ventricular outflow tract area measurements with transesophageal echocardiography after myectomy correlated fairly well with postoperative transesophageal pressure gradients. Patients with residual transthoracic elevated gradients after surgery at follow-up had a smaller transesophageal area and higher transesophageal pressure gradients immediately after the procedure. However, transesophageal pressure gradients after myectomy correlated poorly with follow-up transthoracic gradients at rest.

In vivo measurement of mitral leaflet surface area and subvalvular geometry in patients with asymmetrical septal hypertrophy: insights into the mechanism of outflow tract obstruction

BACKGROUND

Analyzing the determinants of systolic anterior motion of the mitral valve and consequent left ventricular outflow tract (LVOT) obstruction in patients with asymmetrical septal hypertrophy requires a comprehensive 3-dimensional analysis of mitral leaflet (ML) area, papillary muscle (PM) geometry, and the distribution of left ventricular hypertrophy.

METHODS AND RESULTS

Real-time 3-dimensional echocardiography was performed in 47 patients with asymmetrical septal hypertrophy and 32 normal controls. Patients included 20 with resting LVOT obstruction (group I) and 27 without (group II). Customized software (Omni 4D) provided a validated measure of ML surface area, LVOT area, mitral annular area and nonplanarity, LVOT hypertrophy index by topography (percent area with wall thickness >16 mm), and 3-dimensional PM positions relative to annulus. ML area was more than twice as large in group I than normal and 1.4 times normal in group II (P<0.001). Group I patients were also characterized by higher LVOT hypertrophy index and medial and anterior displacements of both PMs, resulting in a shorter inter-PM distance. Independent determinants of LVOT obstruction were indexed total ML area (adjusted odds ratio, 5.651; 95% confidence interval, 1.573 to 20.304; P=0.008) and inter-PM distance (adjusted odds ratio, 0.416; 95% confidence interval, 0.203 to 0.854; P=0.0169). Minimal LVOT area during systole correlated well with peak LVOT pressure gradient (R(2)=0.83, P<0.001); its independent determinants were left ventricular end-systolic volume (P=0.0183), indexed total ML area (P=0.0108), inter-PM distance (P=0.0378), annular height (P=0.0047), and LVOT hypertrophy index (P=0.0098).

CONCLUSIONS

Myocardium is not the only tissue affected in patients with asymmetrical septal hypertrophy, and primary changes of the mitral apparatus, including ML area increase and PM displacement, are independent determinants of LVOT obstruction and provide a comprehensive mechanism that determines leaflet slack and anteriorly directed motion. Abnormal PM-mitral valve geometry assessed by real-time 3-dimensional echocardiography can provide reasonable new targets for individualized intervention.

Single photon emission computed tomography: an alternative imaging modality in left ventricular evaluation

Various diagnostic imaging modalities have been used for quantitative left ventricular (LV) parameters. Because of the suboptimal value of the most widely used technology, two-dimensional (2D) echocardiography, 3D ultrasonographic imaging has improved accuracy for LV volume and function. Single photon emission computed tomography (SPECT) is another diagnostic method where LV volumetric and functional parameters can be accurately provided by gated myocardial perfusion tomographic slices. First pass radionuclide venticulography is another imaging modality which has some practical limitations. Despite lower ejection fraction (EF) values compared with invasive approach, noninvasive techniques are accurate in determination of normal and depressed EF. Noninvasive techniques with 3D approach including gated SPECT are beneficial for not only global but also regional LV evaluation. It has been mentioned that the slight difference between echocardiography and SPECT could be caused by the diverse population studied. The results of diagnostic stress tests support that SPECT is feasible to use in evaluation of LV volume and functional analysis. Magnetic resonance imaging is an expensive modality to use routinely, but it preserves its importance in selected patients for providing precise LV geometric data.

Echocardiography in hypertrophic cardiomyopathy: the role of conventional and emerging technologies

Hypertrophic cardiomyopathy is a relatively common inherited cardiomyopathy that is occasionally challenging to differentiate from hypertensive heart disease and athlete hearts on the basis of morphologic or functional abnormalities alone. Echocardiography has traditionally played a preeminent role in the diagnosis, formulation of management strategies, and the prognostication of this complex disease. In this review, we briefly profile the utility and pitfalls of established echocardiographic modalities and discuss the evolving role of novel echocardiographic imaging modalities such as tissue Doppler, Doppler-based strain, 2-dimensional strain (speckle tracking imaging), and 3-dimensional imaging in the assessment of hypertrophic cardiomyopathy.

Real-time three-dimensional echocardiography: a pilot feasibility study in an Italian cardiologic center

BACKGROUND

The majority of studies demonstrating the diagnostic potential of three-dimensional (3-D) echocardiography have been conducted on selected series of patients in research laboratories.

AIM

To investigate the feasibility and usefulness of real-time 3-D transthoracic echocardiography in daily routine practice.

METHODS

Two hundred consecutive patients underwent standard two-dimensional (2-D) transthoracic echocardiography (TTE) and real-time (RT) 3-D TTE with a commercially available ultrasound system (Sonos 7500 LIVE 3D, Philips Medical Systems). The quality of 3-D acquisitions and post-processed images was graded as: bad, satisfactory, good and demo. In each case, the results of 3-D TTE were compared with 2-D images to disclose additional qualitative information provided by 3-D examination. An additional qualitative information score was given for each cardiac structure.

RESULTS

The mean time of the 3-D examination was 11+/-4 min. The mean time of 2-D transthoracic studies in our laboratory is 25 min and the total time in this series was therefore approximately 36 min. The mean number of acquisitions in our series was 11.5 per patient. The quality was evaluated as bad/insufficient in 7.0%, satisfactory/sufficient in 29.6%, good in 40.2% and demo in 23.2% of all datasets and reconstructions. The structures with greater additional qualitative information scores comprise the anterior and posterior mitralic leaflets, antero-lateral and postero-medial papillary muscles and leaflets of tricuspid valve. The intra- and interobserver reproducibility of quality grading was good and there are few interobserver discrepancies, which were resolved by two physicians, experienced in 3-D echocardiography, not involved in the study.

CONCLUSIONS

RT 3-D TTE may be used in clinical settings with high feasibility rate and may provide additional, clinically quite relevant qualitative information. This technique may expand the abilities of non-invasive cardiology and open new doors for the evaluation of cardiac disease.

Evaluation of left ventricular outflow tract area after septal reduction in obstructive hypertrophic cardiomyopathy: a real-time 3-dimensional echocardiographic study

BACKGROUND

The comparative impact of percutaneous alcohol septal reduction (ASR) and surgical myectomy on the left ventricular outflow tract (LVOT) area in patients with obstructive hypertrophic cardiomyopathy (HC) is not well defined. Real-time 3-dimensional echocardiography (RT3DE) provides accurate information about the LVOT geometry and shape. We aimed to analyze the change in LVOT area after septal reduction interventions in patients with obstructive HC using RT3DE.

METHODS

Thirty-one HC patients (mean age 53 +/- 17 years) undergoing ASR (n = 14) or myectomy (n = 17) were studied at baseline and during follow-up with RT3DE. LVOT area was measured after observing the LVOT in the 3D space as the smallest area during midsystole. LVOT pressure gradients were determined by conventional continuous wave Doppler.

RESULTS

Overall, LVOT area increased from 0.86 +/- 0.20 to 2.50 +/- 0.88 cm2 (P < .01), and the resting LVOT pressure gradient decreased from 64 +/- 41 to 16 +/- 10 mm Hg (P < .01) after a median follow-up of 3 months after intervention (range 1-24 months). A similar significant decrease in LVOT pressure gradients was seen in myectomy and ASR groups (from 62 +/- 39 to 12 +/- 5 mm Hg and from 67 +/- 43 to 21 +/- 14 mm Hg, respectively, P < .01 in between each group, and P = NS between both groups). However, the increase in LVOT area was greater in myectomy than in ASR group (from 0.81 +/- 0.22 to 2.90 +/- 0.64 cm2 and 0.93 +/- to 0.16 to 2.02 +/- 0.92 cm2, respectively, P < .01 between both groups).

CONCLUSION

RT3DE demonstrated an effective increase in LVOT area after both ASR and myectomy. This technique may be useful for assessing the results of septal reduction in patients with obstructive HC.

Impact of left ventricular outflow tract area on systolic outflow velocity in hypertrophic cardiomyopathy: a real-time three-dimensional echocardiographic study

OBJECTIVES

The aim of this study was to use real-time three-dimensional echocardiography (3DE) to investigate the quantitative relation between minimal left ventricular (LV) outflow tract area (A(LVOT)) and maximal LV outflow tract (LVOT) velocity in patients with hypertrophic obstructive cardiomyopathy (HCM).

BACKGROUND

In patients with HCM, LVOT velocity should change inversely with minimal A(LVOT) unless LVOT obstruction reduces the pumping capacity of the ventricle.

METHODS

A total of 25 patients with HCM with systolic anterior motion (SAM) of the mitral valve leaflets underwent real-time 3DE. The smallest A(LVOT) during systole was measured using anatomically oriented two-dimensional "C-planes" within the pyramidal 3DE volume. Maximal velocity across LVOT was evaluated by two-dimensional Doppler echocardiography (2DE). For comparison with 3DE A(LVOT), the SAM-septal distance was determined by 2DE.

RESULTS

Real-time 3DE provided unique information about the dynamic SAM-septal relation during systole, with A(LVOT) ranging from 0.6 to 5.2 cm(2) (mean: 2.2 +/- 1.4 cm(2)). Maximal velocity (v) correlated inversely with A(LVOT) (v = 496 A(LVOT)(-0.80), r = -0.95, p < 0.001), but the exponent (-0.80) was significantly different from -1.0 (95% confidence interval: -0.67 to -0.92), indicating a significant impact of small A(LVOT) on the peak LVOT flow rate. By comparison, the best correlation between velocity and 2DE SAM-septal distance was significantly (p < 0.01) poorer at -0.83, indicating the superiority of 3DE for assessing A(LVOT).

CONCLUSIONS

Three-dimensional echocardiography-measured A(LVOT) provides an assessment of HCM geometry that is superior to 2DE methods. These data indicate that the peak LVOT flow rate appears to be significantly decreased by reduced A(LVOT). Real-time 3DE is a potentially valuable clinical tool for assessing patients with HCM.

Three-Dimensional Echocardiography: The Gateway to Virtual Reality!

Virtual reality (VR) is one of the latest developments in cardiac three-dimensional (3-D) ultrasound. A VR heart model linked to 3-D echocardiographic image datasets provides the observers spatial information regarding a 3-D image dataset and prevents the "lost in space effect" in difficult and relevant coupled diseases when integrated into 3-D reconstruction software. Standardized echocardiographic views can be selected within the integrated developed VR heart model, and this is the first step to automatic 3-D computations with minimal operator interaction. VR heart models open exciting opportunities in the field of teaching echocardiographic cardiology, diagnosis, and examinable states.

Quantitative assessment of the operative results after extended myectomy and surgical reconstruction of the subvalvular mitral apparatus in hypertrophic obstructive cardiomyopathy using dynamic three-dimensional transesophageal echocardiography

OBJECTIVES

The aim of this study was to examine the value of dynamic three-dimensional (3D) transesophageal echocardiography (TEE) for the postoperative evaluation after extended myectomy and surgical reconstruction of the subvalvular mitral valve apparatus in patients with hypertrophic obstructive cardiomyopathy (HOCM).

BACKGROUND

Two-dimensional imaging techniques such as echocardiography, computed tomography and magnetic resonance imaging have not been able to precisely quantify the effects of surgical therapy on the morphology of the left ventricular outflow tract (LVOT).

METHODS

Multiplane TEE with 3D reconstruction was performed in 11 patients before and after the operation and in 16 normal control subjects for comparison. The preoperative maximal systolic pressure gradient in the LVOT was 69 +/- 59 mm Hg. The following variables were measured within the dynamic 3D data set: depth, width, length and cross-sectional area (CSA) gain caused by the myectomy trough, minimal CSA of the LVOT at each time point and its cyclic changes and maximal mitral leaflet deviation during systole.

RESULTS

Functional class improved from 3.0 +/- 0.2 before the operation to 1.5 +/- 0.6 after it. The maximal systolic pressure gradient in the outflow tract decreased to 26 +/- 21 mm Hg postoperatively (p < 0.001). Minimal CSA of the outflow tract increased from 1.1 +/- 1.2 to 3.8 +/- 1.9 cm2 postoperatively (p < 0.001), similar to the value of the control group (4.2 +/- 1.5 cm2, p = NS). The area gain due to the myectomy trough was 1.3 +/- 1.0 cm2, corresponding to 48 +/- 12% of the total operative area difference. Maximal systolic depth of the myectomy was 7 +/- 2 mm, maximal width was 20 +/- 8 mm and length was 28 +/- 7 mm. Maximal deviation of the mitral leaflets fell from 15 +/- 7 to 6 +/- 7 mm postoperatively (p < 0.01). In five patients mass measurements of the intracavitary portion of the papillary muscle (PM) revealed an increase from 7.3 +/- 1.0 to 12.1 +/- 2.5 g due to surgical mobilization of PMs (p < 0.01).

CONCLUSIONS

3D TEE quantifies the differences in outflow tract morphology before and after surgery for HOCM. This technique may have an impact on the planning of operative interventions and allow for the evaluation of its results.