Tomasz Kukulski

Can natural strain and strain rate quantify regional myocardial deformation? A study in healthy subjects

Strain rate (SR) and strain (epsilon) have been proposed as new ultrasound (US) indices for quantifying regional wall deformation, and can be measured from color Doppler myocardial data by determining the local spatial velocity gradient. The aim of this study was to define normal regional SR/epsilon values for both radial and longitudinal myocardial deformation. SR/epsilon profiles were obtained from 40 healthy volunteers. For radial deformation, posterior left ventricular (LV) wall SR/epsilon were calculated. For longitudinal, they were determined for basal, mid- and apical segments of the 1. septum; 2. lateral, 3. posterior and 4. anterior LV walls and for the 5. right ventricular (RV) lateral wall. SR/epsilon values describing radial deformation were higher than the corresponding SR/epsilon values obtained for longitudinal deformation. Longitudinal SR/epsilon were homogeneous throughout the septum and all LV walls. This was in contrast to the normal base-apex velocity gradient. The RV segmental SR/epsilon values were higher than those obtained from the corresponding LV wall and inhomogeneous (higher in the apical segments). SR/epsilon imaging appears to be a robust technique for quantifying regional myocardial deformation.

Identification of acutely ischemic myocardium using ultrasonic strain measurements. A clinical study in patients undergoing coronary angioplasty.

OBJECTIVESnThe goal of this study was to investigate whether the changes in myocardial deformation measured with ultrasonic strain could accurately identify acutely ischemic myocardium during coronary angioplasty.nnnBACKGROUNDnEarly identification of acute myocardial ischemia has important clinical implications. The accuracy of ultrasonic strain for the detection of acute myocardial ischemia has been validated in animal experiments but has not been investigated in the clinical setting.nnnMETHODSnIn 73 patients (64 +/- 12 years), either radial or longitudinal strain values were monitored in the at-risk segments before, during, and early after right, circumflex, and left anterior descending coronary angioplasty. Based on the visual wall motion assessed before the angioplasty, segments were divided into normokinetic (group I) and hypo/akinetic (group II). Strain data in the at-risk segments were compared with values derived from the adjacent nonischemic segments and normal values in 20 controls.nnnRESULTSnCoronary occlusion induced a marked reduction in the systolic strain both in the radial (from 49 +/- 6.9% to 23 +/- 4.6% in group I and from 21.9 +/- 11% to 11.3 +/- 8.4% in group II, p < 0.001) and longitudinal directions. Concomitantly, postsystolic strain increased (from 3.8 +/- 3.1% to 14.6 +/- 9.5% in group I, and from 4.4 +/- 3.7% to 11.3 +/- 7.8% in group II in radial direction, p < 0.001). Upon reperfusion, all deformation parameters returned to near preocclusion values. In comparison with control, baseline, and reperfusion data, the systolic and postsystolic strain parameters measured during total coronary occlusion identified acutely ischemic myocardium with a sensitivity of 86% to 95% and a specificity of 83% to 89%.nnnCONCLUSIONSnIn this model of acute ischemia, ultrasonic strain indexes differentiate acutely ischemic segments from both normal and dysfunctional myocardium. This should be a promising new approach to the bedside monitoring of acute ischemic changes in regional myocardial function.

Abnormal Postsystolic Thickening in Acutely Ischemic Myocardium During Coronary Angioplasty: A Velocity, Strain, and Strain Rate Doppler Myocardial Imaging Study

We report a case in which the combination of gray scale imaging of wall thickness changes allied to color DMI regional velocity, strain, and strain rate data identified the development and regression of diastolic thickening in the acute ischemic segment during a right coronary artery percutaneous transluminal coronary angioplasty (PTCA). We also discuss the possible mechanisms and potential clinical implications of this finding.

A Comparison of Regional Myocardial Velocity Information Derived by Pulsed and Color Doppler Techniques: An In Vitro and In Vivo Study

The objective was to compare velocity information derived from either a tissue mimicking phantom or normal contracting myocardium by both pulsed wave and color Doppler myocardial imaging (PWDMI and CDMI). Both CDMI and PWDMI allow quantitative assessment of regional myocardial contraction and relaxation velocities, but their potential clinical applications have not yet been investigated. Moreover, no information is available as to whether they can be used interchangeably for regional velocity assessment. For the in vitro study, a rotating, circular‐shaped, tissue‐mimicking sponge driven by a motor at speeds of 15, 30, 60, 90 rpm was used to derive velocity data from the same eight points of interest by using PWDMI or CDMI techniques. For the in vivo study, 25 normal subjects were examined at rest using parasternal and apical approaches. Velocity profiles were derived from the same 26 areas of interest (18 left ventricular segments, 3 right ventricular segments, and 5 measurement points for the tricuspid and mitral annuli) for each technique. Peak maximal velocities were detected by PWDMI and peak mean velocities were measured using CDMI. The results of the in vitro study phantom showed excellent correlation (r = 0.99, P < 0.001) and satisfactory agreement (0.04 cm/sec; 3.3 cm/sec) between both Doppler techniques. PWDMI velocities were higher than CDMI velocities by up to 20% and overestimated the real velocity value (0.37 ± 0.29 cm/sec) while CDMI underestimated predicted velocity by 1.35 ± 0.36 cm/sec. Good correlation (r = 0.87, P < 0.001), but poor agreement (−2.1 cm/sec; 5.4 cm/sec) was shown in vivo for all segments with regard to peak systolic and diastolic velocities. Both Doppler techniques cannot be used interchangeably for comparing peak velocities in the clinical situation. However, with adequate temporal resolution, they can be used interchangeably for velocity profile recording and for timing of events.

Relationship of visually assessed apical rocking and septal flash to response and long-term survival following cardiac resynchronization therapy (PREDICT-CRT)

AIMSnApical rocking (ApRock) and septal flash (SF) are often observed phenomena in asynchronously contracting ventricles. We investigated the relationship of visually assessed ApRock and SF, reverse remodelling, and long-term survival in cardiac resynchronization therapy (CRT) candidates.nnnMETHODS AND RESULTSnA total of 1060 patients eligible for CRT underwent echocardiographic examinations before and 12 ± 6 months after device implantation. Three blinded physicians were asked to visually assess the presence of ApRock and SF before device implantation and also their correction by CRT 12 ± 6 months post-implantation. Patients with a left ventricular (LV) end-systolic volume decrease of ≥15% during the first year of follow-up were regarded as responders. Patients were followed for a median period of 46 months (interquartile range: 27-65 months) for the occurrence of death of any cause. If corrected by CRT, visually assessed ApRock and SF were associated with reverse remodelling with a sensitivity of 84 and 79%, specificity of 79 and 74%, and accuracy of 82 and 77%, respectively. ApRock (hazard ratio [HR] 0.40, 95% confidence interval [CI] 0.30-0.53, P < 0.0001) and SF (HR 0.45 [CI 0.34-0.61], P < 0.001) were independently associated with lower all-cause mortality after CRT and had an incremental value over clinical variables and QRS width for identifying CRT responders. Both the absence of ApRock/SF and unsuccessful correction of ApRock/SF despite CRT were associated with a high risk for non-response and an unfavourable long-term survival.nnnCONCLUSIONnA specific LV mechanical dyssynchrony pattern, characterized by ApRock and SF, is associated with a more favourable long-term survival after CRT. Both parameters are also indicators of an effective therapy.

Mid-term outcomes of triple-site vs. conventional cardiac resynchronization therapy: a preliminary study.

BACKGROUNDnThe primary objectives of this study were to compare the implantation course of triple-site (double left-single right) and conventional cardiac resynchronization devices. The secondary target was to assess mid-term outcomes of both types of cardiac resynchronization therapy (CRT).nnnMETHODSnFifty-four patients with NYHA classes III-IV, left ventricular EF<or=35% and QRS>or=120 ms were included; 27 received triple-site pacemakers (TRIV group), 27 conventional CRT devices (BIV group). Procedural course, clinical data, QRS duration, echocardiographic parameters, peak oxygen consumption (VO2max) and 6-minute walking distance (6MWD) were screened for inter-group differences.nnnRESULTSnProcedure duration was higher in TRIV than in BIV group (197.6 vs. 137.6 min, P<0.001), fluoroscopy exposure and complication-rates were similar. After 3 months of CRT, triple-site pacing was associated with a more significant (P<0.05) NYHA class reduction (by 1.4 vs. 1.0 class, respectively), increase in VO(2) max (2.9 vs. 1.1 mL/kg/min) and 6MWD (98.7 vs. 51.6 m) than conventional CRT. A higher EF and more improved intraventricular synchrony were observed in the TRIV than in the BIV group. The response rate in the TRIV group was 96.3% vs. 62.9% in the conventional group (P=0.002). Triple-site stimulation was an independent predictor of response to CRT (adjusted odds ratio 26.4, P=0.01).nnnCONCLUSIONSnTriple-site resynchronization appears to be more beneficial than conventional CRT. Upgrade to triple-site CRT may be considered in non-responders to standard resynchronization.

Quantitation of left-ventricular asynergy by cardiac ultrasound

The clinical evaluation of regional delays in myocardial motion (myocardial asynchrony) has proved problematic, yet it remains an important functional parameter to evaluate. Prior attempts to quantify regional asynergy have met with limited success, often thwarted by the low temporal resolution of imaging-system data acquisition. If a delay in onset of motion of 30-40 msec is clinically important to measure, then data acquisition at frame rates of 50-100 per second is required. This is out of the current temporal resolution of angiographic, nuclear, or magnetic resonance studies. Only cardiac ultrasound can currently achieve the necessary frame rates. Furthermore, quantitative studies into the accuracy with which a trained observer can identify computed regional myocardial asynchrony in a left-ventricular 2-dimensional (2-D) image have shown that regional delays of < 80 msec are not normally recognized in a moving image. This may be improved to 60 msec when either training is undertaken or comparative image review is used. However, this is still out of the temporal resolution required in clinical practice. Thus, visual interpretation of asynchrony is not sufficiently accurate. Two ultrasound data sets based on either integrated backscatter or Doppler myocardial imaging data may provide the solution. Doppler myocardial imaging is a new ultrasound technique which, in either its pulsed or color Doppler format, can achieve the required temporal resolution (with temporal resolutions of 8 msec and 16 msec, respectively). In contrast, color Doppler myocardial imaging, in its curved M-mode format, can display the timing of events during the cardiac cycle for all in-plane myocardial segments. This should allow the quantitation of regional delay for all systolic and diastolic events. Potentially, asynchrony due to regional ischemia, bundle branch block, ventricular premature beats, and ventricular preexcitation could all be identified and the degree of delay quantified. This overview will aim to establish the potential role of these new ultrasound methodologies in the recognition and quantitation of left-ventricular asynergy and how they might best be introduced into clinical practice.

Tissue Doppler Echocardiography: Future Developments

The use of color‐coded tissue Doppler echocardiography has resulted in rapid technological advances in the evaluation of cardiac function. This article describes some of these exciting new advances, including curved M‐mode analysis and strain rate imaging. Data from studies in animals and humans are presented to demonstrate the potential clinical use of this new echocardiographic diagnostic tool.

Many response criteria are poor predictors of outcomes after cardiac resynchronization therapy: validation using data from the randomized trial

AIMSnThe aim of the study was to assess the predictive value for outcomes of various response criteria currently used in patients undergoing cardiac resynchronization therapy (CRT).nnnMETHODS AND RESULTSnData from TRUST CRT randomized trial in patients with New York Heart Association (NYHA) III-IV class, QRS ≥ 120 ms, ejection fraction ≤ 35%, and mechanical dyssynchrony was analysed. Ninety-seven subjects who survived 6 months after implantation of CRT-defibrillator were classified as responders or non-responders depending on 15 criteria used in most of the previous trials. Blindly adjudicated data on major adverse cardiac events (MACEs) within 1 year after classification were used to calculate the predictive value of response criteria. After adjustment for baseline confounding variables only eight criteria were significantly predictive for future MACEs. Sensitivity and specificity ranged substantially for clinical (32-94% and 26-63%) and echocardiographic criteria (40-93% and 22-70%, respectively). The most powerful clinical predictor was >a NYHA class reduction ≥ 1 [adjusted relative risk (RR) 4.41 for non-responders; 95% confidence interval (CI) 1.75-11.04, P = 0.002], while the strongest echocardiographic predictor was a reduction in the left ventricular end-systolic index by > 15% (RR 3.49; 95% CI 1.59-7.64, P = 0.002). A combination of these two criteria did not improve the predictive value of a single parameter. Both criteria showed multiple significant interactions with baseline patients characteristics.nnnCONCLUSIONnOnly some of the commonly used response criteria predict outcome in patients undergoing CRT. The predictive value varies substantially across different criteria, with a higher sensitivity observed for the clinical parameters and a higher specificity observed for echocardiographic parameters. Combining various criteria adds little to their prognostic value. The predictive accuracy of various criteria can be different in various subgroups due to multiple interactions with baseline characteristics. CLINICALTRIALS. GOV IDENTIFIER: NCT00814840.

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.