Myocardial Dyssynchrony and Resynchronization
Section snippets
Myocardial dyssynchrony in heart failure
Heart failure is a common cardiovascular condition with more than 500,000 new cases each year and requiring close to 1 billion dollars in health care expenses [1]. During the last decade or so, several publications have noted the prevalence and unfavorable effects of conduction abnormalities in heart failure [2], [3], [4], [5]. Conduction delay, most often in the lateral wall, results in early activation and contraction of the septum at a time when the lateral wall is quiescent, and thus in
Response to cardiac resynchronization therapy
Despite strong evidence of clinical and morphologic improvement after CRT, there appear to be a number of eligible patients who do not respond to this invasive and expensive therapy [26]. Indeed, some patients may experience increased morbidity after CRT [27]. In an attempt to develop better strategies for identifying patients who are most likely to respond to CRT, various clinical, electrocardiographic, and imaging techniques have been, and continue to be, explored.
All the major clinical
Mechanical synchrony and cardiac resynchronization therapy response
The fundamental abnormality in heart failure patients corrected by CRT is delay in mechanical activation for territories within the LV chamber. It is probably important that early and late regions exist as territories (ie, lateral or posterior wall versus septum) rather than as microdispersed regions throughout the ventricle. Mechanical dyssynchrony can be visually evident by examining regional wall motion, but it is not obvious in most cases. Mechanical dyssynchrony was examined quantitatively
Conventional echocardiography
Conventional and novel echocardiographic techniques have been used to assess both inter- and intraventricular dyssynchrony. Interventricular dyssynchrony denotes mechanical delay in activation of the right and left ventricle. Normally, both ventricles are synchronized and activate almost simultaneously. In heart failure, delayed LV lateral wall activation results in a significant delay in LV ejection, compared with the right ventricle. This interventricular mechanical delay is assessed most
Tissue Doppler echocardiography
Tissue Doppler echocardiography (TDE) uses the Doppler principle to track tissue (myocardial motion) rather than blood flow [39], [40], [41], employing a pulsed Doppler sample volume or a sample volume within a two-dimensional Doppler sector. Tissue Doppler techniques are used commonly to assess myocardial function in cardiomyopathy and ischemia, and during diastole [42], [43], [44], [45], [46], [47], [48], [49]. This method yields the speed at which a particular portion of myocardium moves and
Strain echocardiography
Tissue velocity measures tissue motion (displacement) at a single point along the ultrasound beam and is therefore susceptible to cardiac translational motion and tethering artifacts. Measurement of strain, on the other hand, depicts regional deformation references typically to diastole, and is less susceptible to such artifacts. Initially, strain was determined noninvasively using MRI [56], [57], but now it can be assessed by TDE as well [58], [59], [60], [61]. Although one might expect strain
Contrast echocardiography
Kawaguchi and colleagues [64] explored the use of echocardiographic contrast to obtain information on regional dyssynchrony. This novel echocardiographic method used contrast variability imaging to quantify dyssynchrony. Thirty to fifty consecutive images of the heart, gated to the cardiac cycle, were obtained before and during contrast injection. At each phase and for each pixel, the temporal average and variance were determined from the total set of cycles. The final pixel intensity was set
Three-dimensional echocardiography
Real-time three-dimensional echocardiography (3DE) uses a matrix array transducer to obtain a real-time pyramidal volume scan of the heart. Because real-time scan volumes are relatively narrow, acquisition of real-time images of the entire heart is facilitated by widening the sector and acquiring images from every other cardiac cycle. This is called a full volume acquisition. For quantitative analysis of dyssynchrony using 3DE, the system defines a number of 2D slices through the voxel-based 3D
MRI
MRI allows detailed interrogation of cardiac structure and function with high spatial resolution and is relatively operator independent. Quantitative MRI-based strain techniques have been used to assess myocardial mechanics [56], [57]. The potential advantages of MRI-based techniques for dyssynchrony assessment include excellent reproducibility, high spatial resolution, and the ability to obtain three-dimensional information, including mechanics, in the circumferential orientation [67]. Recent
Strain-encoded MRI
Strain-encoded (SENC) MRI is a new method of measuring regional strain that requires less complex image processing [73]. As a result, it is faster than HARP analysis, which still requires some postprocessing. SENC imaging is derived from a standard myocardial tagging sequence in which the tissue at end-diastole is tagged with a sinusoidal pattern designed to modulate the longitudinal magnetization orthogonal to the imaging plane. Deformation of tissue during systole will change the local
Dyssynchrony indices by MRI
Given the more comprehensive strain data generally obtained by MRI methods, a number of approaches have been developed to assess 3-D dyssynchrony. The methods are not specific to this imaging approach, however, and can be employed as well using TDE-derived measurements.
The regional variance of strain is determined from the variance of strain magnitude obtained from 28 radially displaced segments for each short-axis section and averaged among slices for each time point. This approach is similar
Summary
Conduction abnormalities are noted in a number of patients with heart failure and are associated with altered ventricular mechanics (mechanical dyssynchrony), resulting in reduced and inefficient systolic function. Correction of mechanical dyssynchrony via biventricular pacing (cardiac resynchronization) is associated with substantial symptomatic benefits, reverse remodeling of the left ventricle, reduced hospitalizations for heart failure, and improved survival. However, approximately 30% of
References (75)
- et al.
Alteration of left ventricular performance by left bundle branch block simulated with atrioventricular sequential pacing
Am J Cardiol
(1984) - et al.
Natural history of abnormal conduction and its relation to prognosis in patients with dilated cardiomyopathy
Int J Cardiol
(1996) - et al.
Mapping of regional myocardial strain and work during ventricular pacing: experimental study using magnetic resonance imaging tagging
J Am Coll Cardiol
(1999) - et al.
Acute hemodynamic effects of biventricular DDD pacing in patients with end-stage heart failure
J Am Coll Cardiol
(1998) - et al.
Long-term clinical effect of hemodynamically optimized cardiac resynchronization therapy in patients with heart failure and ventricular conduction delay
J Am Coll Cardiol
(2002) - et al.
Heart failure management using implantable devices for ventricular resynchronization: Comparison of Medical Therapy, Pacing, and Defibrillation in Chronic Heart Failure (COMPANION) trial. COMPANION Steering Committee and COMPANION Clinical Investigators
J Card Fail
(2000) - et al.
Left ventricular dyssynchrony predicts response and prognosis after cardiac resynchronization therapy
J Am Coll Cardiol
(2004) - et al.
Electrocardiographic predictive factors of long-term clinical improvement with multisite biventricular pacing in advanced heart failure
Am J Cardiol
(1999) - et al.
Dual-chamber pacing with a short atrioventricular delay in congestive heart failure: a randomized study
J Am Coll Cardiol
(1995) - et al.
Tissue Doppler imaging predicts improved systolic performance and reversed left ventricular remodeling during long-term cardiac resynchronization therapy
J Am Coll Cardiol
(2002)
Cardiac resynchronization therapy tailored by echocardiographic evaluation of ventricular asynchrony
J Am Coll Cardiol
Predictors of left ventricular reverse remodeling after cardiac resynchronization therapy for heart failure secondary to idiopathic dilated or ischemic cardiomyopathy
Am J Cardiol
Ventricular asynchrony predicts a better outcome in patients with chronic heart failure receiving cardiac resynchronization therapy
J Am Coll Cardiol
A new Doppler method of assessing left ventricular ejection force in chronic congestive heart failure
Am J Cardiol
Assessment of colour Doppler tissue imaging using test-phantoms
Ultrasound Med Biol
Color Doppler myocardial imaging: a new technique for the assessment of myocardial function
J Am Soc Echocardiogr
Doppler echocardiographic measurement of low velocity motion of the left ventricular posterior wall
Am J Cardiol
Doppler tissue echocardiographic features of cardiac amyloidosis
J Am Soc Echocardiogr
Subendocardial motion in hypertrophic cardiomyopathy: assessment from long- and short-axis views by pulsed tissue Doppler imaging
J Am Soc Echocardiogr
Comparative usefulness of myocardial velocity gradient in detecting ischemic myocardium by a dobutamine challenge
J Am Coll Cardiol
Cardiac resynchronization therapy: Part 1–issues before device implantation
J Am Coll Cardiol
Usefulness of the peak velocity difference by tissue Doppler imaging technique as an effective predictor of response to cardiac resynchronization therapy
Am J Cardiol
Usefulness of echocardiographic tissue synchronization imaging to predict acute response to cardiac resynchronization therapy
Am J Cardiol
Utility of echocardiographic radial strain imaging to quantify left ventricular dyssynchrony and predict acute response to cardiac resynchronization therapy
Am J Cardiol
Two-dimensional strain-a novel software for real-time quantitative echocardiographic assessment of myocardial function
J Am Soc Echocardiogr
Quantitation of basal dyssynchrony and acute resynchronization from left or biventricular pacing by novel echo-contrast variability imaging
J Am Coll Cardiol
Assessment of the effect of cardiac resynchronization therapy on intraventricular mechanical synchronicity by regional volumetric changes
Am J Cardiol
Magnetic resonance imaging assessment of ventricular dyssynchrony: current and emerging concepts
J Am Coll Cardiol
Functional abnormalities in isolated left bundle branch block. The effect of interventricular asynchrony
Circulation
Effect of left bundle branch block on diastolic function in dilated cardiomyopathy
Br Heart J
Redistribution of myocardial fiber strain and blood flow by asynchronous activation
Am J Physiol
Mapping propagation of mechanical activation in the paced heart with MRI tagging
Am J Physiol
Mechanical dyssynchrony in dilated cardiomyopathy with intraventricular conduction delay as depicted by 3D tagged magnetic resonance imaging
Circulation
Regional alterations in protein expression in the dyssynchronous failing heart
Circulation
Abnormal conduction and repolarization in late-activated myocardium of dyssynchronously contracting hearts
Cardiovasc Res
Cited by (8)
Multispecialty approach: The need for heart failure disease management for refining cardiac resynchronization therapy
2012, Heart RhythmCitation Excerpt :Early attempts to identify objective criteria for “nonresponse” focused on detecting underlying mechanical (either intraventricular or interventricular) dyssynchrony. This appears to be a logical definition of the intended benefits of CRT because inadequate resynchronization (or an absence of underlying dyssynchrony) may lead directly to a lack of intended benefits following CRT.12 In a prospective series of HF patients who failed to show evidence of either clinical and/or echocardiographic responses after at least 3 months of follow-up post-CRT implantation, it was found that not only device-related factors but also substrate-related and logistic-related factors could be identified as contributing to CRT nonresponse (Table 1).13
Echocardiographic Tools for Cardiac Resynchronization Therapy
2011, Advanced Approaches in EchocardiographyModelling passive diastolic mechanics with quantitative MRI of cardiac structure and function
2009, Medical Image AnalysisIncreased myocardial dysfunction, dyssynchrony, and epicardial fat across the lifespan in healthy males
2014, BMC Cardiovascular Disorders