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

Three-Tesla Magnetic Resonance Imaging Characteristics of Hypertrophic Cardiomyopathy: A Comparison with Several Echocardiography Parameters

Background

Hypertrophic cardiomyopathy (HCM) is a primary cardiac disorder characterized by myocardial hypertrophy without increased afterload. This study set out to describe the cardiac magnetic resonance (CMR) imaging characteristics of HCM and to evaluate correlations of selected CMR parameters with echocardiography.

Methods

This cross-sectional study enrolled 46 patients diagnosed at the Vietnam Heart Institute with HCM and underwent CMR at the Radiology Center, Bach Mai Hospital, from July 2021 to September 2022.

Results

A left ventricular outflow tract (LVOT)/aortic valve (AO) diameter ratio of ≥0.38 on CMR was consistent with an LVOT pressure gradient (PG) of <30 mmHg on echocardiography. The LVOT diameter and the LVOT/AO diameter ratio differed significantly between obstructive and non-obstructive HCM. The predominant phenotypes were diffuse asymmetric HCM (32.6%) and septal HCM (37%), followed by apical HCM (6.5%). Most late gadolinium enhancement (LGE) lesions were observed in the mid-wall of the hypertrophic segments. The mean LGE mass was significantly higher in the obstructive group than in the non-obstructive HCM group (p < 0.05). A strong negative correlation (r = -0.66) was found between the LVOT/AO diameter ratio on the CMR and the LVOT PG via echocardiography. Moreover, echocardiography detected morphologic risk factors for sudden cardiac death (SCD) in 80.4% of patients, whereas the corresponding proportion detected by CMR was 91.3%. Patients with systolic anterior motion (SAM) had a risk for a LVOT/AO diameter ratio <0.38, which was 5.7 times the risk observed in their counterparts without SAM.

Conclusions

The LVOT/AO diameter ratio detected by CMR is a precise index for classifying hemodynamic HCM groups. CMR was better than echocardiography for SCD risk stratification.

Preintervention imaging and intraoperative management care of the hypertrophic obstructive cardiomyopathy patient

With an estimated overall mortality of less than 1 percent per year, hypertrophic cardiomyopathy, is the most common genetic cardiomyopathy. Intraoperative transesophageal echocardiography is the standard of care for assessing patients with hypertrophic obstructive cardiomyopathy undergoing surgical septal myectomy, allowing surgical planning, intraoperative hemodynamic monitoring, and postprocedural assessment of the repair, including detection of immediate complications. At various phases during surgical septal myectomy, the changing hemodynamic conditions may lead to worsening or improvement in left ventricle outflow tract obstruction by change in preload or afterload, systolic anterior motion of the mitral valve, or sympathetic stimulation. These characteristics represent unique challenges in the management of these patients, requiring a comprehensive understanding of the management of all the conditions required to decrease the left ventricle outflow tract gradient avoiding obstruction, which include the maintenance of sinus rhythm, adequate rate avoiding tachycardia and bradycardia, and avoidance of systemic hypotension preserving preload and afterload, with adequate vasoactive agents. The aim of this review is to summarize the perioperative assessment and management of patients undergoing hypertrophic obstructive myopathy surgery.

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.

Alcohol Septal Ablation to Prevent Left Ventricular Outflow Tract Obstruction During Transcatheter Mitral Valve Replacement: First-in-Man Study

OBJECTIVES

This study evaluates outcomes of pre-emptive alcohol septal ablation (ASA) to prevent iatrogenic left ventricular outflow tract (LVOT) obstruction after transcatheter mitral valve replacement (TMVR).

BACKGROUND

LVOT obstruction is a life-threatening complication of TMVR. Bail-out ASA has been described as a therapeutic option for patients with outflow obstruction during TMVR, but little is known about pre-emptive ASA.

METHODS

Multicenter registry of patients with severe mitral valve disease who underwent pre-emptive ASA to mitigate LVOT obstruction risk after TMVR. High risk of LVOT obstruction was predicted in all patients by pre-procedural computed tomographic imaging.

RESULTS

Thirty patients (age 76.1 ± 7.7 years; women 76.7%) with severe mitral valve disease underwent pre-emptive ASA to mitigate TMVR-induced LVOT obstruction risk. Twenty patients underwent mitral valve replacement (14 transseptal, 3 transatrial, 1 transapical, 1 transseptal with percutaneous laceration of anterior mitral leaflet, 1 treated with surgical mitral valve replacement). Eight patients experienced clinical improvement post-ASA. Two patients died before TMVR. Median increase in neo-LVOT surface area post-ASA was 111.2 mm² (interquartile range: 71.4 to 193.1 mm²). Five patients (16.7%) required pacemaker implantation post-ASA. In-hospital and 30-day mortality post-ASA was 6.7% (2/30 patients). After ASA, TMVR was performed successfully in 100% of attempted cases. In-hospital and 30-day mortality post-TMVR was 5.3% (1/19). Mortality of entire cohort was 10% (3/30 patients: 2 post-ASA before TMVR, 1 died 30 days post-TMVR).

CONCLUSIONS

Pre-emptive ASA is associated with a significant increase in predicted neo-LVOT area before TMVR and may enable safe TMVR in patients usually excluded secondary to prohibitive risk of LVOT obstruction.

The Mitral Coaptation to Ventricular Septal Space: Two- and Three-Dimensional Transesophageal Echocardiographic Assessment

OBJECTIVES

To assess the dimensions and changes in the CSEPT (space between the ventricular septum and mitral coaptation point) before and after cardiopulmonary bypass (CPB) and to compare patients with and without aortic valve stenosis (AS) undergoing cardiac surgery.

DESIGN

Retrospective review of intraoperative transesophageal echocardiographic examinations.

SETTING

Single academic medical center.

PARTICIPANTS

The study comprised 91 elective cardiac surgical patients-30 with AS scheduled for aortic valve replacement and 61 without AS (non-AS).

INTERVENTIONS

Two- and 3-dimensional (2D and 3D) analysis of the CSEPT before and after CPB.

MEASUREMENTS AND MAIN RESULTS

Assessment of the CSEPT distances and areas was performed using 2D and 3D imaging before and after CPB. Two-dimensional measures of CSEPT distances were performed using midesophageal 5-chamber and long-axis windows. Three-dimensional measures were performed offline using multiplanar reconstruction. The CSEPT space was smaller after CPB (p < 0.01). Before and after CPB, the midesophageal 5-chamber and long-axis windows were similar to each other, and both were larger than the pre-CPB 3D CSEPT distance. Patients with AS had smaller before and after CPB distances and areas compared with non-AS patients (p < 0.05). The change in CSEPT area in AS patients was 24%.

CONCLUSIONS

The CSEPT space is smaller after CPB and more so for patients with AS undergoing aortic valve replacement. Two-dimensional CEPT distances vary compared with 3D CSEPT distances. Additional study using Doppler analysis will elucidate the added value of 3D assessment of the CSEPT space.

Transcatheter Mitral Valve Repair and Replacement: Current Evidence for Intervention and the Role of CT in Preprocedural Planning-A Review for Radiologists and Cardiologists Alike

The mitral valve is a complex structure with a three-dimensional saddle shape annulus. Mitral regurgitation occurs from leaflet coaptation failure that is either primary (a problem with the leaflets) or secondary (chamber dilatation in the setting of cardiomyopathy). There has been an increase in focus on transcatheter mitral valve interventions, for both mitral repair and replacement. These technologies have rapidly developed to provide treatment for a substantial number of patients with severe symptomatic mitral regurgitation who are at too high of a risk to undergo open heart surgery. CT assessment of the mitral valve has developed with equal rapidity, with regard to preprocedural planning for transcatheter therapies. This review will provide an overview of mitral valve anatomy, an update on the current transcatheter repair and replacement therapies, as well as a focused overview of the role of multislice CT in mitral assessment prior to intervention. © RSNA, 2020.

Surgical management of left ventricular outflow obstruction in hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy is the single most common form of inherited heart disease. Left ventricular outflow tract obstruction (LVOTO) is a recognised feature of this condition which arises when blood leaving the outflow tract is impeded by systolic anterior motion of the mitral valve. In an important minority of patients, breathlessness, chest pain and syncope may result and persist despite the use of medications. In suitable candidates, surgery may relieve obstruction and its associated symptoms, and normalise life expectancy. Refinements in surgical techniques have marked improvements in the understanding of mechanisms underlying LVOTO. In this review, we hope to provide the reader with an understanding of how contemporary surgical practice has developed, which patients should be considered for surgery, and what results are anticipated. The role echocardiography plays in this area is highlighted throughout.

Three-Dimensional Echocardiographic Evaluation of Mitral Apparatus during Preload Manipulation in Patients with Hypertrophic Cardiomyopathy

BACKGROUND

The three-dimensional (3D) dynamic change of mitral geometry during preload manipulation has not been fully investigated. We investigated how preload manipulation affected the mitral apparatus geometry in hypertrophic cardiomyopathy (HCM) patients using 3D echocardiography.

METHODS AND RESULTS

Twenty five HCM patients, thirteen with obstructive HCM (HOCM) and twelve with nonobstructive HCM (HNCM), and six healthy controls were studied. Subjects underwent 3D echocardiography during rest, leg raising, the Valsalva maneuver, and the Valsalva maneuver after nitroglycerin intake (NTG-Valsalva). Left ventricular outflow tract (LVOT) pressure gradients, mitral annular area, annular circumference, and the tenting volume of the mitral leaflets were measured. Standardized annular area significantly decreased during the NTG-Valsalva maneuver in all 3 groups (▵2.23 mm(2) /m(2) in control, P = 0.031; ▵0.46 mm(2) /m(2) in HNCM, P = 0.012; ▵1.3 mm(2) /m(2) in HOCM, P = 0.013). Standardized annular area decrease during the Valsalva maneuver alone was more prominent in HNCM patients (▵0.57 mm(2) /m(2) , P = 0.009) than HOCM patients (▵0.3 mm(2) /m(2) , P = 0.094). Standardized mitral tenting volume during the NTG-Valsalva maneuver significantly decreased only in HOCM patients (▵1.18 mm(3) /m(2) , P = 0.046).

CONCLUSION

Decreased mitral annular area and changes in leaflets tenting volume during preload reduction might affect the development of LVOT obstruction. Our data suggest the importance of preserving the saddle-shaped of the mitral annulus in management of HCM with LVOT obstruction.

The influence of aortoseptal angulation on provocable left ventricular outflow tract obstruction in hypertrophic cardiomyopathy

Objectives

Aortoseptal angulation (AoSA) can predict provocable left ventricular outflow tract obstruction (LVOTO) in patients with symptomatic hypertrophic cardiomyopathy (HCM). Lack of a standardised measurement technique in HCM without the need for complex three-dimensional (3D) imaging limits its usefulness in routine clinical practice. This study aimed to validate a simple measurement of AoSA using 2D echocardiography and cardiac MR (CMR) imaging as a predictor of LVOTO.

Methods

We retrospectively assessed 160 patients with non-obstructive HCM, referred for exercise stress echocardiography. AoSA was measured using resting 2D echocardiography in all patients, and CMR in 29. Twenty-five controls with normal echocardiograms were used for comparison.

Results

Patients with HCM had a reduced AoSA compared with controls (113°±12 vs 126°±6), p<0.0001. Sixty (38%) patients had provocable LVOTO, with smaller angles than non-obstructive patients (108°±12 vs 116°±12, p<0.0001). AoSA, degree of mitral valvular regurgitation and incomplete systolic anterior motion (SAM) were associated with peak left ventricular outflow tract gradient (r=0.508, p<0.0001). An angle ≤100° had 27% sensitivity, 91% specificity and 59% positive predictive value for predicting provocable LVOTO. When combined with SAM, specificity was 99% and positive predictive value 88%. Intraclass correlation coefficient of AoSA measured by two observers was 0.901 (p<0.0001). Bland-Altman analysis of echocardiographic AoSA showed good agreement with the CMR-derived angle.

Conclusions

Measurement of AoSA using echocardiography in HCM is easy, reproducible and comparable to CMR. Patients with provocable LVOTO have reduced angles compared with non-obstructive patients. AoSA is highly specific for provocable LVOTO and should prompt further evaluation in symptomatic patients without resting obstruction.

[Severe left ventricular outflow tract obstruction as a complication of mitral valve repair: case report]

Systolic anterior motion (SAM) is a postoperative complication of mitral valve repair, with an incidence of 5 to 10%. Early recognition of the signs and symptoms of SAM is essential for the management of these patients. This article focuses on the pathophysiology and dynamics of SAM and the treatment strategies described in the literature. The authors present a case study and echocardiographic images illustrating the clinical relevance of the mechanism involved, in order to clarify whether surgical reintervention is necessary.

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.

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.

Effect of Obstruction on Longitudinal Left Ventricular Shortening in Hypertrophic Cardiomyopathy

OBJECTIVES

We investigated the cause of the midsystolic drop (MSD) in left ventricular (LV) ejection velocities that are observed with hypertrophic cardiomyopathy (HCM) and severe obstruction.

BACKGROUND

Dynamic obstruction is an important determinant of symptoms and adverse outcome. The MSD in velocity and flow occurs in patients with gradients >60 mm Hg. The nadir velocity in the LV occurs simultaneously with peak gradient.

METHODS

We studied 36 patients with obstructive HCM and an MSD and compared them with 15 patients with HCM and no obstruction and with 25 age-matched normal control subjects. We measured LV ejection velocity proximal and distal to LV obstruction as well as tissue Doppler velocities and time intervals.

RESULTS

The duration of contraction of both the septum and lateral wall is shorter in obstructed patients with the MSD than in nonobstructed HCM patients: septal contraction 203 +/- 68 ms vs. 271 +/- 41 ms (p < 0.001). Parallel reduction in the length of shortening was noted: 1.2 +/- 0.6 cm vs. 1.9 +/- 0.4 cm (p < 0.001). The ejection velocity nadir follows the septal and lateral peak velocities by 100 ms and 60 ms, respectively. The velocity nadir occurs as both walls rapidly decelerate to their premature termination: septal deceleration 79 +/- 35 cm/s2 vs. 48 +/- 21 cm/s2 (p < 0.001). With medical abolition of obstruction the MSD disappears and the duration and length of contraction normalizes.

CONCLUSIONS

These data indicate that the MSD is caused by premature termination of LV segmental shortening and is a manifestation of systolic dysfunction.

[Three-dimensional echography: cardiovascular applications]

Real-time three-dimensional echocardiography is currently used in a standard echocardiographic examination. Volume-rendered images better identify and locate anatomic structures and improve our comprehensive approach to various heart diseases. The assessment of mitral valve disease and congenital cardiopathies and the measurement of left ventricular mass, volume, and ejection fraction are the three main applications of three-dimensional echocardiography. Three-dimensional vascular imaging is an emerging and promising application of three-dimensional echography. The near future of three-dimensional echography requires the integration of all modalities of conventional echography in three dimensional probes, a higher image resolution compared to the current situation, as well as the development of real-time three-dimensional probes dedicated to transesophageal cardiac or vascular examination.

Asymmetry of Systolic Anterior Motion of the Mitral Valve in Patients with Hypertrophic Obstructive Cardiomyopathy: A Real-time Three-dimensional Echocardiographic Study

By geometric analysis of real-time 3-dimensional echocardiography performed in 39 patients with hypertrophic obstructive cardiomyopathy and definite systolic anterior motion of the mitral valve, we found that the angle between the mitral annular plane and basal portion of the anterior mitral valve leaflet, and the angle between the basal portion of the anterior leaflet and its tip portion measured in the medial and central anteroposterior planes, were significantly smaller than those in the lateral plane. The distance between the interventricular septum and the anterior mitral valve tip in the medial and central plane was also significantly smaller than that in the lateral plane. The lateral distance between the interventricular septum and the anterior mitral valve tip was the only independent determinant of left ventricular outflow tract pressure gradient by multiple stepwise regression analysis. In conclusion, systolic anterior motion of the mitral valve develops predominantly in the medial side, resulting in laterally located narrow left ventricular outflow tract opening in patients with hypertrophic obstructive cardiomyopathy.

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.

Volume measurements in nuclear medicine gated SPECT and 4D echocardiography: validation using a dynamic cardiac phantom

PURPOSE

A dynamic cardiac phantom was used as a reference to compare volumes measured with gated SPECT and 4D echocardiography.

MATERIAL AND METHODS

Gated SPECT data were acquired with a standard single-head gamma camera, and the volume reconstructions were carried out using the Mirage software by Segami. 4D echocardiography used a new prototype of rotating scan head to acquire ultrasound images during a cardiac cycle, used to reconstruct the volume deformations as a function of time. End-diastolic volume, end-systolic volume, and ejection fraction were measured using both gated SPECT and 4D echocardiography.

RESULTS

The results obtained showed a good correlation between volumes measured with the two modalities, but a slight overestimation of volumes with gated SPECT. The influence of filtering and pixel size parameters on the measured volumes was quantified for gated SPECT, in order to correct the overestimation.

CONCLUSION

The agreement between gated SPECT (after correction) and 4D echocardiography confirmed the relevance of the comparisons. This study was an initial step before conducting clinical trials to compare exhaustively left ventricular volumes obtained with the two modalities.

Visualization of coronary arteries using intravenous contrast agent and real-time 3-dimensional echocardiography in a patient with hypertrophic cardiomyopathy

Real-time 3-dimensional echocardiography is a recently developed imaging technique that provides unique information on spatial geometry in real time. We described an asymptomatic patient with hypertrophic obstructive cardiomyopathy for whom 3-dimensional echocardiography was performed after intravenous injection of perfluorocarbon-filled microbubbles. It resulted in enhancement of the left ventricular endocardial border delineation and myocardial perfusion in the hypertrophic septum. A clear visualization of the entire course of the left anterior descending coronary artery and its septal perforator branches was obtained. This case illustrates the potential of real-time 3-dimensional echocardiography to improve the anatomic evaluation of coronary arteries, especially when combined with contrast agents.

Usefulness of real-time three-dimensional echocardiography for evaluation of myectomy in patients with hypertrophic cardiomyopathy

Real-time 3-dimensional echocardiography was performed in 10 patients with obstructive hypertrophic cardiomyopathy (HC) before and after myectomy and in 6 controls. The exact location of systolic anterior motion of the mitral leaflet was shown in all patients with HC with a predominant involvement of the medial portion in 4 patients and the middle portion in 6 patients. The smallest area of the left ventricular outflow tract was significantly smaller in patients with HC than in controls (1.4 +/- 0.7 vs 5.1 +/- 1.2 cm(2), p <0.01), significantly increased after myectomy (4.8 +/- 1.8 cm2, p <0.01) and was associated with a reduction of the pressure gradient at rest from 63 +/- 41 to 15 +/- 5 mm Hg (p <0.01).

Biphasic left ventricular outflow and its mechanism in hypertrophic obstructive cardiomyopathy

BACKGROUND

Biphasic systolic velocity in the left ventricular (LV) outflow tract (LVOT) occurs in hypertrophic obstructive cardiomyopathy (HOCM). The cause and importance of this observation remain poorly understood.

METHODS

A total of 25 patients with HOCM were matched to 30 control subjects. A function derived from the relation of flow in the proximal descending aorta to that in the LVOT was used to estimate the LVOT systolic flow rate in HOCM. Patients with HOCM were grouped by absence (group I) or presence (group II) of biphasic LVOT velocity.

RESULTS

Biphasic LVOT velocity was associated with biphasic estimated LVOT outflow (P =.002). The LVOT pressure gradient was inversely related to LV outflow rate at the time of the peak gradient (r = -.64, P <.001). Dobutamine increased the gradient and reduced LVOT outflow at the time of the peak gradient. In group II, mitral-septal separation occurred despite a LVOT gradient (36 mm Hg).

CONCLUSION

Biphasic LVOT flow in HOCM occurs and may be caused by "afterload mismatch." The late systolic increase in flow is related to mitral-septal separation. Resolution of systolic anterior motion occurs despite a persistent LVOT pressure gradient, implying a role for forces other than pressure differences.

SAM-systolic anterior motion of the anterior mitral valve leaflet post-surgical mitral valve repair

Systolic anterior motion (SAM) is a postoperative complication experienced by patients undergoing mitral valve repair. The incidence of SAM after mitral valve repair ranges from 5 to 10%. Early recognition of the signs and symptoms of SAM is imperative to the management of these patients. This article presents the pathophysiology of mitral valve dysfunction to give the practitioner a clear understanding of the dynamics of SAM. This article's main focus is the detection and management of SAM and the most current treatment modalities. A case study is used to illustrate the complex management necessary for the patient with SAM.

Validation of a volumic reconstruction in 4-d echocardiography and gated SPECT using a dynamic cardiac phantom

A dynamic cardiac phantom was used as a reference to compare the volumes reconstructed with 4-D echocardiography and gated single-photon emission computed tomography (SPECT). 4-D echocardiography used a new prototype of rotating scan head to acquire ultrasound (US) images during a cardiac cycle, associated with a new protocol (left ventricular 4-D or LV 4-D) to reconstruct the volume deformations of the heart as a function of time. Gated SPECT data were acquired with a standard single-head gamma camera, and the reconstructions were carried out using the Mirage software released by Segami. The influences of different LV 4-D parameters were tested and analyzed. End-diastolic volume, end-systolic volume, and ejection fraction were measured using both LV 4-D and gated SPECT. Results obtained showed a straight correlation between the two examinations. The agreement confirmed the relevance of the comparisons. This study is an initial step before conducting clinical trials to exhaustively compare the two modalities.