Ventricular Mechanical Dyssynchrony Research Articles

Right Ventricular Apical Pacing Acutely Impairs Left Ventricular Function and Induces Mechanical Dyssynchrony in Patients with Sick Sinus Syndrome: A Real-time Three-dimensional Echocardiographic Study

Chronic right ventricular apical (RVA) pacing can lead to an increased risk of heart failure. However, assessment of left ventricular mechanical dyssynchrony in the whole left ventricle simultaneously with acute RVA pacing has never been investigated. This study included 35 patients with sick sinus syndrome and intact intrinsic atrioventricular conduction. All patients received dual-chamber pacemaker implants with atrial leads placed in the right atrial appendage and right ventricle leads positioned in the RVA. Transthoracic two-dimensional echocardiography, tissue Doppler echocardiography, and real-time three-dimensional echocardiography were performed to determine the chamber size, dyssynchronization index, myocardial performance index, and global left ventricular ejection fraction. The myocardial performance index was significantly higher with RVA pacing (with RVA 0.42 +/- 0.18 vs. without RVA 0.31 +/- 0.14; P = .004), and left ventricular ejection fraction derived by real-time three-dimensional echocardiography was significantly lower with RVA pacing (with RVA 54.4% +/- 7.7% vs. without RVA 56.7% +/- 7.9%; P = .013), indicating deteriorated left ventricular function with RVA pacing. In addition, there was significant difference in the intraventricular delays in favor of without RVA pacing when assessed by the septal-to-posterior wall motion delay on the midventricular level (with RVA 91.9 +/- 52.5 msec vs. without RVA 38.6 +/- 28.9 msec; P < .0001) and when assessed by real-time three-dimensional echocardiography-derived systolic dyssynchrony index (with RVA 7.00% +/- 2.54% vs. without RVA 5.36 +/- 2.17%; P = .0003). Acute RVA pacing can induce left ventricular mechanical dyssynchrony and impair left ventricular function in patients with sick sinus syndrome.

549 Left ventricular mechanical dyssynchrony assessed with 3D real time echocardiography and ejection fraction in patients with previous myocardial infarction, dilated cardiomyopathy and controls

549 Left ventricular mechanical dyssynchrony assessed with 3D real time echocardiography and ejection fraction in patients with previous myocardial infarction, dilated cardiomyopathy and controls

Evaluation of global left ventricular function and mechanical dyssynchrony in patients with an asymptomatic left bundle branch block: A real-time 3D echocardiography study

A left bundle branch block (LBBB) affects both global left ventricular (LV) function and mechanical dyssynchrony. The aim was to evaluate global LV function and mechanical dyssynchrony with real-time 3D echocardiography (RT3DE), in asymptomatic LBBB patients, healthy volunteers and patients with symptomatic heart failure (HF) and a LBBB. Furthermore, the relation between presence or absence of symptoms of HF and mechanical dyssynchrony was investigated. RT3DE was performed in 61 consecutive patients: 16 healthy volunteers, 22 patients with an asymptomatic LBBB and 23 patients with symptomatic HF and a LBBB. Global LV function and the systolic dyssynchrony index (SDI) were measured. In healthy volunteers, mean LV ejection fraction was 54 +/- 5%, in asymptomatic LBBB patients 50 +/- 9%, and in HF patients 29 +/- 9%. SDI was 5.6 +/- 3.6%, 7.3 +/- 3.2% and 12.8 +/- 4.8% for healthy volunteers, asymptomatic LBBB patients and HF patients respectively. SDI differed significantly between HF patients and both other groups. A cut-off value for SDI for presence of symptoms of HF was 10.8%. Asymptomatic LBBB patients have more depressed global LV function than healthy volunteers have; patients with symptoms of HF and a LBBB have severe global LV dysfunction. Asymptomatic LBBB patients have an intermediate mechanical dyssynchrony; HF patients with a LBBB have the most severe mechanical dyssynchrony. A substantial amount of mechanical dyssynchrony might be accompanied by the presence of symptoms of HF.

Evaluation of left ventricular mechanical dyssynchrony as determined by phase analysis of ECG-gated SPECT myocardial perfusion imaging in patients with left ventricular dysfunction and conduction disturbances

Cardiac resynchronization therapy (CRT) is approved for the treatment of patients with advanced systolic heart failure and evidence of dyssynchrony on electrocardiograms. However, a significant percentage of patients do not demonstrate improvement with CRT. Echocardiographic techniques have been used for more accurate determination of dyssynchrony. Single photon emission computed tomography (SPECT) myocardial perfusion imaging has not previously been used to evaluate cardiac dyssynchrony. The objective of this study is to evaluate mechanical dyssynchrony as described by phase analysis of gated SPECT images in patients with left ventricular dysfunction, conduction delays, and ventricular paced rhythms. A novel count-based method is used to extract regional systolic wall thickening amplitude and phase from gated SPECT images. Five indices describing the phase dispersion of the onset of mechanical contraction are determined: peak phase, phase SD, bandwidth, skewness, and kurtosis. These indices were determined in consecutive patients with left ventricular dysfunction (n = 120), left bundle branch block (n = 33), right bundle branch block (n = 19), and ventricular paced rhythms (n = 23) and were compared with normal control subjects (n = 157). Phase SD, bandwidth, skewness, and kurtosis were significantly different between patients with left ventricular dysfunction, left bundle branch block, right bundle branch block, and ventricular paced rhythms and normal control subjects (all P < .001) Peak phase was significantly different between patients with right ventricular paced rhythms and normal control subjects (P = .001). A novel SPECT technique for describing left ventricular mechanical dyssynchrony has been developed and may prove useful in the evaluation of patients for CRT.

Improvement of left ventricular mechanical dyssynchrony associated with restoration of left ventricular function in a patient with fulminant myocarditis and complete left bundle branch block

A 52-year-old woman with fulminant myocarditis had completed left bundle branch block (LBBB) and severely impaired left ventricular (LV) function. Marked mechanical dyssynchrony with septal-to-posterior delay of 389 ms was observed by echocardiographic speckle tracking radial strain imaging on admission, which was dramatically improved to 106 ms after total recovery from acute myocarditis with restoration of LV ejection fraction whereas her electrocardiogram still showed complete LBBB.

Triple site biventricular pacing in a patient with congestive heart failure and severe mechanical dyssynchrony

We report on a case of a 62-year-old patient with symptomatic heart failure and severe ventricular electrical and mechanical dyssynchrony, who was implanted percutaneously with a triple site (dual-left single-right) resynchronization device. At 3-months follow-up, the patient's functional status improved significantly as shown by subjective and objective tests. Furthermore, this mode of pacing has allowed nearly complete inter- and intraventricular mechanical resynchronization.

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Evidence of left ventricular dyssynchrony resulting from right ventricular pacing in patients with severely depressed left ventricular ejection fraction

Cardiac resynchronization therapy (CRT) has recently emerged as an effective treatment for patients with moderate-to-severe systolic heart failure and left bundle branch block (LBBB). Right ventricular pacing (RVP) leads to an LBBB-like pattern in the electrocardiogram. The aim of this study was to evaluate the frequency of ventricular mechanical dyssynchrony in patients induced by RVP. The study included 33 patients with a conventional single or dual chamber pacemaker, 18 with ejection fraction (EF) > 35% and 15 with EF < or = 35%. In all patients, an intrinsic rhythm without intraventricular conduction delay (QRS < or = 120 ms) was present without RVP. Two-dimensional and Doppler echocardiographic criteria for mechanical dyssynchrony [aortic pre-ejection delay (APE), interventricular mechanical delay (IVMD), delayed activation of the posterior left ventricular wall (PD), septal-to-posterior wall motion delay (SPWMD)] were evaluated in all patients with and without RVP. QRS duration showed no difference between the two EF-groups without RVP (93 +/- 10 vs. 96 +/- 9 ms), but was significantly longer in patients with low EF with RVP (152 +/- 18 vs. 181 +/- 18 ms; P < 0.001). In patients with EF > 35%, only APE was slightly prolonged by RVP (111 +/- 20 vs. 129 +/- 17 ms; P = 0.03), whereas in patients with EF < or = 35% marked pathological differences in APE (118 +/- 29 vs. 169 +/- 24 ms; P < 0.001), IVMD (22 +/- 17 vs. 58 +/- 14 ms; P < 0.001), SPWMD (103 +/- 28 vs. 125 +/- 29 ms; P = 0.004), and PD (-21 +/- 25 vs. - 39 +/- 25 ms; P = 0.005) were found. A significant correlation between QRS duration and mechanical ventricular dyssynchrony was only found for two echocardiographic parameters (IVMD, APE) with RVP. In patients with a conventional pacemaker, mechanical dyssynchrony with RVP was shown exceptionally in patients with preserved or moderately depressed systolic left ventricular (LV) function, but in nearly all patients with severely depressed systolic LV function. These patients might benefit from CRT when frequent RVP is required.

Acute decrease of left ventricular mechanical dyssynchrony and improvement of contractile state after left ventricular restoration

Objective: Surgical left ventricular restoration (SVR) by means of endoventricular patch aneurysmectomy in patients with post infarction aneurysm should result in acutely improved left ventricular performance. This study tests the capacity of geometric rebuilding by SVR to reconstitute a more synchronous and synergic contractile pattern.

906 Serial evaluation of global left ventricular function and mechanical dyssynchrony in patients with an isolated left bundle branch block using real-time 3D echocardiography

906 Serial evaluation of global left ventricular function and mechanical dyssynchrony in patients with an isolated left bundle branch block using real-time 3D echocardiography

Left ventricular resynchronization predicted by individual performance of right and left univentricular pacing: A study on the impact of sequential biventricular pacing on ventricular dyssynchrony

There is increasing evidence that improvement in left ventricular (LV) mechanical dyssynchrony is correlated with LV functional recovery in patients undergoing cardiac resynchronization therapy (CRT). Recent studies have suggested that sequential biventricular pacing may be important for further optimizing parameters of ventricular dyssynchrony. The purpose of this study was to evaluate the acute effect of varying sequential biventricular pacing settings on echocardiographic parameters of ventricular dyssynchrony and to identify predictors of the optimal setting. Twenty-nine patients referred for CRT were evaluated with standard echocardiography and tissue Doppler imaging before and after implantation. Indices of interventricular and intraventricular dyssynchrony were assessed for trends during simultaneous and sequential biventricular pacing. Twelve patients (41%) demonstrated linear trends of decreasing systolic dyssynchrony index with increasing LV preactivation. The mean additional decrease in dyssynchrony index at the optimized setting compared with simultaneous biventricular pacing was 26% (P <.04). Twenty-two patients (76%) demonstrated linear trends to decreasing interventricular dyssynchrony with increasing LV preactivation. The trends were strongly correlated with the magnitude of difference of the respective dyssynchrony measures in right ventricular only and LV only univentricular pacing. A significantly, superior capacity of LV only pacing for ventricular resynchronization was found in this subgroup of patients. In patients undergoing CRT, differences in the performance of univentricular pacing are associated with linear trends in ventricular dyssynchrony parameters in sequential biventricular pacing. Quantitative differences in LV univentricular pacing impact on the capacity of biventricular pacing to correct ventricular dyssynchrony.

Cardiac resynchronization therapy: Role of patient selection

Cardiac resynchronization therapy (CRT) is a well-accepted and effective therapy for treating patients with a wide QRS complex, significant left ventricular systolic dysfunction, and symptoms of advanced heart failure. However, approximately 25% to 30% of patients fail to respond to this therapy. Most large studies have used electrical dyssynchrony (wide QRS) as a main entrance criterion. Emerging data suggest that mechanical dyssynchrony may be a more important factor in selecting appropriate candidates for CRT. New echocardiographic (ECHO) imaging modalities such as tissue Doppler imaging, three-dimensional ECHO, and speckle tracking ECHO are able to quantify left ventricular mechanical dyssynchrony. These techniques are currently being used to assist in the selection of patients for CRT. Recently published and ongoing studies are addressing the use of CRT in patients who do not meet the standard criteria, such as patients with atrial fibrillation, mild to moderate heart failure, narrow QRS complex, and acute myocardial infarction.

Cardiac Motion Analysis to Improve Pacing Site Selection in CRT

The aim of the study is to build cardiac wall motion models to characterize mechanical dyssynchrony and predict pacing sites for the left ventricle of the heart in cardiac resynchronization therapy (CRT). Cardiac magnetic resonance imaging data from 20 patients are used, in which half have heart failure problems. We propose two spatio-temporal ventricular motion models to analyze the mechanical dyssynchrony of heart: radial motion series and wall motion series (a time series of radial length or wall thickness change). The hierarchical agglomerative clustering technique is applied to the motion series to find candidate pacing sites. All experiments are performed separately on each ventricular motion model to facilitate performance comparison among models. The experimental results demonstrate that the proposed methods perform as well as we expect. Our techniques not only effectively generate the candidate pacing sites list that can help guide CRT, but also derive clustering results that can distinguish the heart conditions between patients and normals perfectly to help medical diagnosis and prognosis. After comparing the results between two different ventricular motion models, the wall motion series model shows a better performance. In a traditional CRT device deployment, pacing sites are selected without efficient prediction, which runs the risk of suboptimal benefits. Our techniques can extract useful wall motion information from ventricular mechanical dyssynchrony and identify the candidate pacing sites with maximum contraction delay to assist pacemaker implantation in CRT.

Left-sided implantation of a biventricular implantable cardioverter-defibrillator in dextrocardia

A 63-year-old man with situs inversus had undergone aortic valve replacement and mitral valve repair in 1997. In April 2006, he received a transvenous DDD biventricular implantable cardioverter-defibrillator (ICD; Medtronic 7200 InSync Sentry with Medtronic leads: 5076 atrial, 6949 right ventricular, and 4194 bipolar left ventricular lead in a posterior coronary vein) for dilated nonischemic cardiomyopathy (left ventricular ejection fraction 25%), refractory congestive heart failure, left bundle branch block, and left ventricular (LV) mechanical dyssynchrony (80 ms septal to posterior wall by tissue Doppler imaging according to the method of Bax et al1).

Surgical ventricular restoration in patients with ischemic dilated cardiomyopathy: Evaluation of systolic and diastolic ventricular function, wall stress, dyssynchrony, and mechanical efficiency by pressure-volume loops

Surgical ventricular restoration aims at improving cardiac function by normalization of left ventricular shape and size. Recent studies indicate that surgical ventricular restoration is highly effective with an excellent 5-year outcome in patients with ischemic dilated cardiomyopathy. We used pressure-volume analysis to investigate acute changes in systolic and diastolic left ventricular function, mechanical dyssynchrony and efficiency, and wall stress. In 3 patient groups (total, n = 33), pressure-volume loops were measured by conductance catheter before and after surgery. The main study group consisted of 10 patients with ischemic dilated cardiomyopathy (New York Heart Association class III/IV, left ventricular ejection fraction <30%) who had surgical ventricular restoration and coronary artery bypass grafting. In this group, 7 patients had additional restrictive mitral annuloplasty. To assess potential confounding effects of restrictive mitral annuloplasty and cardiopulmonary bypass, we included a group of 10 patients (New York Heart Association class III/IV, left ventricular ejection fraction <30%) who had isolated restrictive mitral annuloplasty and a group of 13 patients with preserved left ventricular function who had isolated coronary artery bypass grafting. After surgical ventricular restoration, end-diastolic and end-systolic volumes were reduced from 211 +/- 54 to 169 +/- 34 mL (P = .03) and from 147 +/- 41 to 110 +/- 59 mL (P = .04), respectively. Left ventricular ejection fraction (from 27% +/- 7% to 37% +/- 13%, P = .04) and end-systolic elastance (from 1.12 +/- 0.71 to 1.57 +/- 0.63 mm Hg/mL, P = .03) improved. Peak wall stress (from 358 +/- 108 to 244 +/- 79 mm Hg, P < .01) and mechanical dyssynchrony (from 26% +/- 4% to 19% +/- 6%, P < .01) were reduced, whereas mechanical efficiency improved (from 0.34 +/- 13 to 0.49 +/- 0.14, P = .03). End-diastolic pressure increased (from 13 +/- 6 to 20 +/- 5 mm Hg, P < .01), whereas the diastolic chamber stiffness constant tended to be increased (from 0.021 +/- 0.009 to 0.037 +/- 0.021 mL(-1), NS). Surgical ventricular restoration achieves normalization of left ventricular volumes and improves systolic function and mechanical efficiency by reducing left ventricular wall stress and mechanical dyssynchrony.

Velocity Vector Imaging to Quantify Ventricular Dyssynchrony and Predict Response to Cardiac Resynchronization Therapy

Velocity vector imaging is a novel quantitative echocardiographic technique that was applied to routine grayscale echocardiographic images of 23 patients with heart failure who underwent cardiac resynchronization therapy. The hypothesis was tested that velocity vector imaging can quantify left ventricular mechanical dyssynchrony and predict response to resynchronization therapy. Tissue velocities were determined by the automated tracking of periodic B-mode image patterns on digital cine loops from standard apical 4-chamber, 2-chamber, and long-axis views, with the user tracing the mid left ventricular wall from a single frame. Dyssynchrony was determined as the greatest opposing wall peak longitudinal systolic velocity delay from the 3 views. Responders, defined as those with >or=15% increases in the ejection fraction, had greater baseline dyssynchrony than nonresponders (opposing wall velocity delays of 131 +/- 83 vs 52 +/- 60 ms, p <0.05), and >or=75 ms predicted response with 85% sensitivity and 80% specificity when followed 8 +/- 5 months after resynchronization therapy. Baseline electrocardiographic QRS duration was not predictive in the same patients. In conclusion, echocardiographic velocity vector imaging has potential for clinical utility.

Pathobiology of Left Ventricular Dyssynchrony and Resynchronization

Left ventricular mechanical dyssynchrony has recently been recognized as a significant contributor to increased morbidity and mortality in some patients with congestive heart failure. Ventricular dyssynchrony compromises global cardiac mechanical efficiency, induces changes in regional hypertrophy and blood flow, and results in local alterations in myocardial protein expression. Cardiac resynchronization therapy has both immediate and long-term beneficial effects on global cardiac function, and has been shown to reduce both morbidity and mortality in heart failure patients. The effects of resynchronization on the tissue-level and molecular consequences of dyssynchrony remain unknown.

A futuristic perspective on clinical studies of cardiac resynchronization therapy for heart failure patients

Heart failure is a major public health problem. Many heart failure patients have electrical and mechanical ventricular dyssynchrony, which are risk factors for death in heart failure patients. Cardiac resynchronization therapy, by stimulating both ventricles, is a strategy to improve ventricular dyssynchrony. This paper describes the historic development of this therapy; reviews the results of completed clinical cardiac resynchronization therapy studies, and discusses ongoing and future studies.

Quantification of left ventricular mechanical dyssynchrony by conductance catheter in the failing heart: Effect of biventricular pacing

Objectives: Mechanical dyssynchrony is important codeterminant of cardiac dysfunction in heart failure. We evaluated new indexes to quantify temporal and spatial aspects of mechanical dyssynchrony derived from on-line segmental conductance catheter signals.

Ventricular mechanical dyssynchrony and resynchronization therapy in heart failure: a new indication for Fourier analysis of gated blood-pool radionuclide ventriculography

In patients with decreased left ventricular ejection fraction and conduction disease, ventricular mechanical dyssynchrony has been demonstrated. To date, resynchronization by biventricular pacing is increasingly used since it improves ventricular function and exercise capacity in patients with heart failure. To optimize and evaluate the effect of resynchronization therapy and to identify patients who may benefit from biventricular pacing the assessment of left ventricular synchronicity is essential. Therefore, a non-invasive and reproducible technique to obtain information on ventricular synchrony is clinically valuable. In this review, the technical background and the role of phase analysis of gated blood-pool nuclear ventriculography in the assessment of ventricular mechanical synchrony, especially in heart failure patients subjected to biventricular pacing, will be discussed.