Reasons for nonadherence to guidelines for aortic valve replacement in patients with severe aortic stenosis and potential solutions

The official guidelines for the treatment of patients with valvular heart disease have given a class I indication for aortic valve replacement in patients with symptomatic, severe aortic stenosis (AS). However, many patients with symptomatic, severe AS do not undergo AVR. We sought to determine the proportion and characteristics of patients with severe AS who do not undergo AVR in a university hospital and to identify the reasons for the lack of surgical referrals, despite the class I guideline indications. We retrospectively studied consecutive patients from an academic hospital with severe AS, as determined by echocardiographic criteria. The records were reviewed for clinical presentation, co-morbidities, surgical intervention, and outcomes. Of the 106 patients with severe AS, 33 (31%) had undergone AVR and 73 (69%) had not. Of those patients without AVR, 31 (42%) were symptomatic. The most common reason the patients with symptomatic, severe AS did not undergo AVR was their symptoms were thought to be unrelated to AS. Of the 42 patients (58%) who were deemed asymptomatic, only 4% had undergone exercise stress testing. With an average follow-up of 15 months, 15 (14%) of the 73 patients who did not undergo AVR died. In patients with severe AS, physicians commonly underrecognize symptoms and overestimate the operative risk. The exercise stress tests were underused in determining which patients with severe AS were symptomatic. As a result, many patients with a class I indication for AVR, who would benefit from this life-saving intervention, do not receive it.

Registration of coronary venous anatomy to the site of the latest mechanical contraction

OBJECTIVE

Cardiac resynchronization therapy (CRT) provides a therapeutic option for patients with congestive heart failure (CHF). There is evidence that the optimal pacing site (OIS) is vicinal to the region of the latest contraction (RLC). However, the RLC is not identified routinely to guide lead implantation to the coronary venous system (CVS). The aim of this study was: (i) to develop a software over-imposing CVS-anatomy on parametric images of left ventricular dyssynchrony in a 3D-format obtained from computed tomography (CT) and cardiac magnetic resonance imaging (MRI); and (ii) to apply this 3D-software for analysing the possible correlation between functional/ clinical improvement and the distance between final implantation site (FIS) and RLC.

METHODS AND RESULTS

In 20 CHF-patients (11 men, 65.6 +/- 6.8 y, ejection fraction (EF): 27.5 +/- 6.1%) CRT-leads were implanted; follow-up included echocardiographic and exercise evaluation. The OIS and the FIS were noted on 3D-registrations and the distances OIS-RLC and FIS-RLC measured.The target vessel was reached in 14 cases. NYHA class and EF improved significantly with a low rate of non-responders of 3 (15%) (EF) and 4 (20%) (NYHA). Image registration was possible in all patients. Post-process 3D-analysis revealed no correlation between the distance FIS-RLC and functional or echocardiographic improvements.There was a trend towards a shorter distance FIS-RLC in patients classified as responders (EF). NYHA class improved significantly better in patients with target vessel implantation.

CONCLUSIONS

Registration of CT/MRI-images enables efforts to reach the RLC by preoperative identification of corresponding veins. Larger randomized trials must define the definite therapeutic benefit.

Quantitative evaluation of regional left ventricular function using three-dimensional speckle tracking echocardiography in patients with and without heart disease

Although 2-dimensional (2D) speckle tracking echocardiography has been shown to be useful in the assessment of regional left ventricular function, it is limited by the assumption that speckles can be tracked frame-to-frame within the imaging plane, even though the cardiac motion is 3-dimensional (3D). Our goal was to evaluate new 3D-speckle tracking echocardiographic (STE) software by (1) comparing the regional wall motion measurements against 2D-STE images, and (2) testing its ability to identify regional wall motion abnormalities. The 2D images and real-time 3D data sets (Toshiba) obtained from 32 subjects were analyzed to measure segmental radial and longitudinal displacements and rotation, as well as the radial, longitudinal, and circumferential strains. The intertechnique comparisons included regression and Bland-Altman analyses. Additionally, cardiac magnetic resonance images (Siemens 1.5 T) acquired the same day were reviewed by an expert who classified the segments as normal or abnormal. The values of each 3D-STE index were compared between the normal and abnormal segments. The 3D-STE and 2D-STE indexes did not correlate well (r = 0.16 to 0.76) and showed wide limits in intertechnique agreement (2 SD: 5 to 6 mm for displacements, 14 degrees rotation, 17% to 52% strains) despite only minimal biases, indicating that these 2 techniques are not interchangeable. In normal segments, 3D-STE showed greater displacements, reflecting the out-of-plane motion component; smaller SDs, indicating tighter normal ranges; and a gradual decrease in radial and longitudinal displacement and a reversal in rotation from the base to the apex. In the abnormal segments, all 3D-STE indexes were reduced, reaching significance for 5 of 6 indexes. In conclusion, this is the first study to evaluate the new 3D-STE technique for measurement of regional wall motion indexes. Our findings have demonstrated its superiority over 2D-STE.

Feasibility of regional and global left ventricular shape analysis from real-time 3d echocardiography

Combined assessment of left ventricular (LV) shape and function could provide new insights into the process of LV remodeling. Real-time 3D echocardiography (RT3DE) allows rapid and accurate semi-automated extraction of LV endocardial surfaces. Our aims were to quantify LV morphology both globally and regionally, using new ellipsoidal (E), spherical (S) and conical (C) shape indices, in a large population in order to define normal values. During systole the LV became less spherical and more conical, while E index remained unchanged. LV volume estimation was more affected by operator subjectivity than C and S indexes computation. These results constitute a reference for future comparisons with serial follow-up of patients during LV remodeling.

Feasibility of left ventricular shape analysis from transthoracic real-time 3-D echocardiographic images

Despite the potential ability of left ventricular (LV) shape analysis to provide independent information complementary to ventricular size and function, in clinical practice only ejection fraction (EF) is currently assessed while LV shape is not routinely quantified. Moreover, geometric assumptions in the computation of EF from multiple two-dimensional (2-D) cut-planes by disc summation or area-length methods, introduce inaccuracies in the estimates. Also, previous approaches for the quantification of LV shape were based on geometric modeling and, as a result, proved inaccurate. Our aims were (1) to develop and test a three-dimensional (3-D) technique for direct quantification of LV shape from real-time 3-D echocardiographic (RT3DE) images without the need for geometric modeling using a new class of LV shape indices; and (2) to study the relationship between these indices and ventricular size and function in normal and abnormal ventricles. Spherical (S), ellipsoidal (E) and conical (C) shape indices were calculated using custom software for analysis of transthoracic RT3DE images on both global and regional levels and initially tested on computer simulated objects of different shapes. The feasibility of using these indices to differentiate between normal and abnormal ventricles was tested in three groups of patients: normal volunteers (NL, n=9), dilated cardiomyopathy (DCM, n=9) and coronary artery disease with apical regional wall motion abnormalities (RWMA, n=9). Computer simulation demonstrated that these shape indices are size-independent and can correctly classify the simulated objects. In human ventricles, both S and C but not E correlated well with LV volumes and EF. Also, S and C changed throughout the cardiac cycle while E remained almost constant. In addition, both regional and global S and C were able to identify differences between NL and abnormal ventricles: normal ventricles were less spherical and more conical than those of patients with DCM at both end-systole and end-diastole (p<0.05) both globally and regionally. In contrast, in patients with RWMA, similar differences were noted only at end-systole, both on a global level and in the apical region. In this study, we demonstrated the feasibility of quantifying LV shape from transthoracic RT3DE images at both global and regional levels. Potentially, such 3-D shape analysis could be combined with conventional evaluation of LV volume and function to provide a more comprehensive assessment of left ventricular performance.

Use of real time three-dimensional transesophageal echocardiography in intracardiac catheter based interventions

BACKGROUND

Real-time three-dimensional (RT3D) echocardiography is a recently developed technique that is being increasingly used in echocardiography laboratories. Over the past several years, improvements in transducer technologies have allowed development of a full matrix-array transducer that allows acquisition of pyramidal-shaped data sets. These data sets can be processed online and offline to allow accurate evaluation of cardiac structures, volumes, and mass. More recently, a transesophageal transducer with RT3D capabilities has been developed. This allows acquisition of high-quality RT3D images on transesophageal echocardiography (TEE). Percutaneous catheter-based procedures have gained growing acceptance in the cardiac procedural armamentarium. Advances in technology and technical skills allow increasingly complex procedures to be performed using a catheter-based approach, thus obviating the need for open-heart surgery.

METHODS

The authors used RT3D TEE to guide 72 catheter-based cardiac interventions. The procedures included the occlusion of atrial septal defects or patent foramen ovales (n=25), percutaneous mitral valve repair (e-valve clipping; n=3), mitral balloon valvuloplasty for mitral stenosis (n=10), left atrial appendage obliteration (n=11), left atrial or pulmonary vein ablation for atrial fibrillation (n=5), percutaneous closures of prosthetic valve dehiscence (n=10), percutaneous aortic valve replacement (n=6), and percutaneous closures of ventricular septal defects (n=2). In this review, the authors describe their experience with this technique, the added value over multiplanar two-dimensional TEE, and the pitfalls that were encountered.

RESULTS

The main advantages found for the use RT3D TEE during catheter-based interventions were (1) the ability to visualize the entire lengths of intracardiac catheters, including the tips of all catheters and the balloons or devices they carry, along with a clear depiction of their positions in relation to other cardiac structures, and (2) the ability to ability to demonstrate certain structures in an "en face" view, which is not offered by any other currently available real-time imaging technique, enabling appreciation of the exact nature of the lesion that is undergoing intervention.

CONCLUSION

RT3D TEE is a powerful new imaging tool that may become the technique of choice and the standard of care for guidance of selected percutaneous catheter-based procedures.

Feasibility, safety, and efficacy of real-time three-dimensional transoesophageal echocardiography for guiding device closure of interatrial communications: initial clinical experience and impact on radiation exposure

AIMS

Our aim was to assess the feasibility and safety of real-time (RT) three-dimensional (3D) transoesophageal echocardiography (TEE) for guiding transcatheter closure of interatrial communications and to evaluate its additional benefit over conventional 2D TEE in reducing radiation exposure for the patient.

METHODS AND RESULTS

Twenty-five patients undergoing device closure of their interatrial defect had the procedure guided by fluoroscopy, 2D TEE, and RT 3D TEE. We retrospectively compared this group with a historical control group in which interventional guidance was performed using fluoroscopy and 2D TEE alone. The application of RT 3D TEE allowed safe device deployment in all patients without any complications, resulting in a reduction of mean fluoroscopy time (10 +/- 6 to 6 +/- 4 min, P < 0.01), mean dose area product (DAP) (964 +/- 628 to 535 +/- 464 cGy cm(2), P < 0.01), and mean DAP per individual body surface area (494 +/- 317 to 273 +/- 221 cGy cm(2)/m(2), P < 0.01).

CONCLUSION

RT 3D TEE as an adjunct to 2D TEE is a feasible and safe tool to guide transcatheter device closure of interatrial communications, resulting in a reduction of radiation exposure. These data indicate that RT 3D TEE can be used to safely monitor interatrial defect closure in clinical routine.

Role of echocardiography in selection of patients for biventricular pacing therapy

Cardiac resynchronization therapy (CRT) has demonstrated improved quality of life, New York Heart Association class, left ventricular ejection fraction, and survival in patients with moderate to severe heart failure, left ventricular ejection fraction less than or equal to 35%, and a prolonged QRS duration. QRS duration remains the primary surrogate for mechanical dyssynchrony, defining the pathophysiology of abnormal regional mechanical activation. Studies have demonstrated that 30% to 40% of patients who meet current criteria for CRT are nonresponders. Therefore, there is great interest in the relationship between electrical and mechanical dyssynchrony, and the ability of each alone or together to predict response remains unknown. Echocardiographic approaches have emerged to quantify mechanical dyssynchrony with greater specificity than QRS duration alone. Although these methods are complex, exciting, and highly accurate for predicting response to CRT in single-center studies, they lack widespread applicability and validation to replace current criteria for device implantation. Use of echocardiography to define dyssynchrony and the impact of promising imaging methods for future patient selection for CRT are discussed.

Volumetric quantification of myocardial perfusion using analysis of multi-detector computed tomography 3D datasets: comparison with nuclear perfusion imaging

BACKGROUND

Although the ability of multi-detector computed tomography (MDCT) to detect perfusion abnormalities associated with acute and chronic myocardial infarction (MI) has been demonstrated, this methodology is based on visual interpretation of selected 2D slices.

OBJECTIVES

We sought to develop a new technique for quantitative volumetric analysis of myocardial perfusion from 3D datasets and test it against resting nuclear myocardial perfusion imaging (NMPI) reference.

METHODS

We studied 44 patients undergoing CTCA: a control group of 15 patients and a study group of 29 patients. MDCT datasets acquired for CTCA were analyzed using custom software designed to: (1) generate bull's eye display of myocardial perfusion and (2) calculate a quantitative index of extent and severity of perfusion abnormality, Q(H), for 16 volumetric myocardial segments. Visual interpretation of MDCT-derived bull's eyes was compared with rest NMPI scores using kappa statistics of agreement on a coronary territory and patient basis. Quantitative MDCT perfusion data were correlated with rest NMPI summed scores and used for objective detection of perfusion defects.

RESULTS

Visual analysis of MDCT-derived bull's eyes accurately detected perfusion defects in agreement with NMPI (kappa = 0.70 by territory; 0.79 by patient). Quantitative data were in good agreement with NMPI, as reflected by: (1) correlation of 0.87 (territory) and 0.84 (patient) between summed Q(H) and NMPI scores, (2) area under ROC curve 0.87 with sensitivity of 0.79-0.92, specificity 0.83-0.91, and accuracy 0.83-0.89 for objective detection of abnormalities.

CONCLUSIONS

Our new technique for volumetric analysis of 3D MDCT images allows accurate objective detection of perfusion defects. This perfusion information can be obtained without additional radiation or contrast load, and may aid in elucidating the significance of coronary lesions.

Impaired exercise tolerance and skeletal muscle myopathy in sulfonylurea receptor-2 mutant mice

By sensing intracellular energy levels, ATP-sensitive potassium (K(ATP)) channels help regulate vascular tone, glucose metabolism, and cardioprotection. SUR2 mutant mice lack full-length K(ATP) channels in striated and smooth muscle and display a complex phenotype of hypertension and coronary vasospasm. SUR2 mutant mice also display baseline cardioprotection and can withstand acute sympathetic stress better than normal mice. We now studied response to a form of chronic stress, namely that induced by 4 wk of daily exercise on SUR2 mutant mice. Control mice increased exercise capacity by 400% over the training period, while SUR2 mutant mice showed little increase in exercise capacity. Unexercised SUR2 mutant showed necrotic and regenerating fibers in multiple muscle skeletal muscles, including quadriceps, tibialis anterior, and diaphragm muscles. Unlike exercised control animals, SUR2 mutant mice did not lose weight, presumably due to less overall exertion. Unexercised SUR2 mutant mice showed a trend of mildly reduced cardiac function, measured by fractional shortening, (46 +/- 4% vs. 57 +/- 7% for SUR2 mutant and control, respectively), and this decrease was not exacerbated by chronic exercise exposure. Despite an improved response to acute sympathetic stress and baseline cardioprotection, exercise intolerance results from lack of SUR2 K(ATP) channels in mice.

The use of intracardiac echocardiography and other intracardiac imaging tools to guide noncoronary cardiac interventions

The limitations of standard fluoroscopy have led to the development of improved imaging techniques to guide noncoronary cardiac interventions. Imaging tools that are used in the interventional laboratory can be categorized as invasive and noninvasive. Noninvasive cardiac imaging tools include ultrasound, computed tomography, and magnetic resonance imaging. These modalities can generate high-resolution images of the heart and are increasingly being used to guide cardiac interventions. Despite these advances, there remains a strong role for invasive imaging tools in the interventional laboratories. Such invasive imaging tools include transesophageal echocardiography, intracardiac echocardiography, intracardiac endoscopy, and electroanatomic mapping systems. Despite the risks inherent to the invasive nature of these tools, these modalities can provide excellent real-time, detailed images that can be invaluable in guiding certain cardiac interventions. This review will propose the features of an ideal intracardiac imaging tool, summarize the intracardiac imaging tools that are currently available or under development to guide noncoronary cardiac interventional procedures, and suggest opportunities for improvement. One opportunity in this field is to couple imaging systems directly with the interventional devices themselves. The use of intracardiac imaging to guide select cardiac procedures including transseptal catheterization, catheter ablation procedures for arrhythmias, and percutaneous placement of cardiac valves and closure devices will also be discussed. Most of this review will be devoted to intracardiac echocardiography, which currently has the broadest number of applications.