Kenji Shiino

Intervendor consistency and reproducibility of left ventricular 2D global and regional strain with two different high-end ultrasound systems

Aims We aimed to assess intervendor agreement of global (GLS) and regional longitudinal strain by vendor-specific software after EACVI/ASE Industry Task Force Standardization Initiatives for Deformation Imaging. Methods and results Fifty-five patients underwent prospective dataset acquisitions on the same day by the same operator using two commercially available cardiac ultrasound systems (GE Vivid E9 and Philips iE33). GLS and regional peak longitudinal strain were analyzed offline using corresponding vendor-specific software (EchoPAC BT13 and QLAB version 10.3). Absolute mean GLS measurements were similar between the two vendors (GE −17.5 ± 5.2% vs. Philips −18.9 ± 5.1%, P = 0.15). There was excellent intervendor correlation of GLS by the same observer [r = 0.94, P < 0.0001; bias −1.3%, 95% CI limits of agreement (LOA) −4.8 to 2.2%). Intervendor comparison for regional longitudinal strain by coronary artery territories distribution were: LAD: r = 0.85, P < 0.0001; bias 0.5%, LOA −5.3 to 6.4%; RCA: r = 0.88, P < 0.0001; bias −2.4%, LOA −8.6 to 3.7%; LCX: r = 0.76, P < 0.0001; bias −5.3%, LOA −10.6 to 2.0%. Intervendor comparison for regional longitudinal strain by LV levels were: basal: r = 0.86, P < 0.0001; bias −3.6%, LOA −9.9 to 2.0%; mid: r = 0.90, P < 0.0001; bias −2.6%, LOA −7.8 to 2.6%; apical: r = 0.74; P < 0.0001; bias −1.3%, LOA −9.4 to 6.8%. Conclusions Intervendor agreement in GLS and regional strain measurements have significantly improved after the EACVI/ASE Task Force Strain Standardization Initiatives. However, significant wide LOA still exist, especially for regional strain measurements, which remains relevant when considering vendor-specific software for serial measurements.

Left Ventricular Global Strain Analysis by Two-Dimensional Speckle-Tracking Echocardiography: The Learning Curve

Background The application of left ventricular (LV) global strain by speckle‐tracking is becoming more widespread, with the potential for incorporation into routine clinical echocardiography in selected patients. There are no guidelines or recommendations for the training requirements to achieve competency. The aim of this study was to determine the learning curve for global strain analysis and determine the number of studies that are required for independent reporting. Methods Three groups of novice observers (cardiology fellows, cardiac sonographers, medical students) received the same standardized training module prior to undertaking retrospective global strain analysis on 100 patients over a period of 3 months. To assess the effect of learning, quartiles of 25 patients were read successively by each blinded observer, and the results were compared to expert for correlation. Results Global longitudinal strain (GLS) had uniform learning curves and was the easiest to learn, requiring a minimum of 50 patients to achieve expert competency (intraclass correlation coefficient > 0.9) in all three groups over a period of 3 months. Prior background knowledge in echocardiography is an influential factor affecting the learning for interobserver reproducibility and time efficiency. Short‐axis strain analysis using global circumferential stain and global radial strain did not yield a comprehensive learning curve, and expert level was not achieved by the end of the study. Conclusions There is a significant learning curve associated with LV strain analysis. We recommend a minimum of 50 studies for training to achieve competency in GLS analysis. HighlightsThere are no current guidelines on training and competency for strain analysis.There is a learning curve for global longitudinal strain analysis.Minimum requirement of 50 studies recommended to achieve competency.Background in echocardiography influences interobserver reproducibility and time efficiency.

Thermoeffector Responses at a Fixed Rate of Heat Production in Heart Failure Patients

PurposeHeart failure (HF) patients seem to exhibit altered thermoregulatory responses during exercise in the heat. However, the extent to which these responses are altered due to physiological impairments independently of biophysical factors associated with differences in metabolic heat production (Hprod), evaporative heat balance requirements (Ereq), and/or body size is presently unclear. Therefore, we examined thermoregulatory responses in 10 HF patients and 10 age-matched controls (CON) similar in body size during exercise at a fixed rate of Hprod and therefore Ereq in a 30°C environment. MethodsRectal temperature, local sweat rate, and cutaneous vascular conductance were measured throughout 60 min of cycle ergometry. Whole-body sweat rate was estimated from pre–post nude body weight corrected for fluid intake. ResultsDespite exercising at the same rate of Hprod (HF, 338 ± 43 W; CON, 323 ± 31 W; P = 0.25), the rise in rectal temperature was greater (P < 0.01) in HF (0.81°C ± 0.16°C) than in CON (0.49°C ± 0.27°C). In keeping with a similar Ereq (HF, 285 ± 40 W; CON, 274 ± 28 W; P = 0.35), no differences in whole-body sweat rate (HF, 0.45 ± 0.11 L·h−1; CON, 0.41 ± 0.07 L·h−1; P = 0.38) or local sweat rate (HF, 0.96 ± 0.17 mg·cm−2·min−1; CON, 0.79 ± 0.15 mg·cm−2·min−1; P = 0.50) were observed between groups. However, the rise in cutaneous vascular conductance was lower in HF than in CON (HF, 0.83 ± 0.42 au·mm Hg−1; CON, 2.10 ± 0.79 au·mm Hg−1; P < 0.01). In addition, the cumulative body heat storage estimated from partitional calorimetry was similar between groups (HF, 154 ± 106 kJ; CON, 196 ± 174 kJ; P = 0.44). ConclusionsCollectively, these findings demonstrate that HF patients exhibit a blunted skin blood flow response, but no differences in sweating. Given that HF patients had similar body heat storage to that of CON at the same Hprod, their greater rise in core temperature can be attributed to a less uniform internal distribution of heat between the body core and periphery.

Impact of high-intensity endurance exercise on regional left and right ventricular myocardial mechanics.

Aims Strenuous endurance exercise acutely increases myocardial wall stress and evokes transient functional cardiac perturbations. However, it is unclear whether exercise-induced functional cardiac disturbances are ubiquitous throughout the myocardium or are segment specific. The aim of this study was to examine the influence of high-intensity endurance exercise on global and segmental left (LV) and right (RV) ventricular tissue deformation (strain). Methods and results Echocardiography was used to measure strain in 23 active men (age: 28 ± 2 years; VO2 peak: 4.5 ± 0.7 L min−1) at rest and during a standardized low-intensity exercise challenge, before and after a 90-min high-intensity endurance cycling intervention. Following the cycling intervention, LV and RV global strain decreased at rest (LV: −18.4 ± 0.4% vs. −17.7 ± 0.4%, P < 0.05; RV: −27.6 ± 0.7% vs. −26.4 ± 0.6%, P < 0.05) and by a greater extent during the low-intensity exercise challenge (LV: −21.3 ± 0.4% vs. −19.2 ± 0.5%, P < 0.01; RV: −28.4 ± 0.8% vs. −23.5 ± 0.9%, P < 0.01). Reductions in LV strain were unique to regions of RV attachment (e.g. LV septum: −24.4 ± 0.5% vs. −21.4 ± 0.6%, P < 0.01) with lateral (−18.9 ± 0.4% vs. −18.4 ± 0.5%) and posterior segments (−19.5 ± 0.4% vs. −18.8 ± 0.7%) unaffected. Similarly, augmentation of strain from rest to exercise was abolished in the RV free wall (−1.1 ± 1.0% vs. 2.9 ± 1.2%, P < 0.01), reduced in the septum (−4.6 ± 0.4% vs. −2.4 ± 0.5%, P < 0.01), and unchanged in the lateral (−1.2 ± 0.6% vs. −0.9 ± 0.6%) and posterior walls (−1.7 ± 0.6% vs. −1.3 ± 0.7%). Conclusion Changes in ventricular strain following high-intensity exercise are more profound in the right ventricle than in the left ventricle. Reductions in LV strain were unique to the septal myocardium and may reflect ventricular interactions secondary to exercise-induced RV dysfunction.

Reproducibility of global left atrial strain and strain rate between novice and expert using multi-vendor analysis software

Left atrial (LA) strain is an emerging technique with potential applications including arrhythmia prediction in atrial fibrillation and early identification of atrial dysfunction. The aim of this study was to evaluate reproducibility of LA strain and strain rate (SR) using multi-vendor analysis software between novice and expert. For LA strain to be a reliable tool, the technique must be reproducible by observers with variable experience. Use of multi-vendor analysis software allows serial strain assessment when echocardiographic images are acquired using different vendors. Fifty subjects underwent 2D-Speckle tracking echocardiographic (STE) derived LA strain and SR analysis measured from apical four and two-chamber views. Three strain parameters of LA function were assessed: reservoir (S-LAs, SR-LAs), contractile (S-LAa, SR-LAa) and conduit (S-LAs–S-LAa, SR-LAe). Strain analyses were performed by 2 independent, blinded novice and expert observers using multi-vendor analysis software. Intraobserver and interobserver analyses were performed using intra class correlation coefficients (ICC) and Bland–Altman analysis. LA strain and SR measured by novice observer demonstrated excellent intraobserver reproducibility (ICC for all strain and SR values > 0.88). There was good interobserver agreement of LA strain values between novice and expert (S-LAs:ICC 0.81, S-LAe:ICC 0.82, S-LAa:ICC 0.74). SR values also demonstrated good interobserver agreement (SR-LAs:ICC 0.83, SR-LAe:ICC 0.79, SR-LAa:ICC 0.86). Of all parameters, SR-LAa had the best interobserver and intraobserver agreement (ICC 0.86, 0.96). Global LA strain and SR values were highly reproducible by novice strain reader using multi-vendor analysis software. Interobserver reproducibility between novice and experts were good and acceptable within limits of agreement.

A new approach to assess myocardial work by non-invasive left ventricular pressure–strain relations in hypertension and dilated cardiomyopathy

Aims Non-invasive left ventricular (LV) pressure-strain loop (PSL) provides a novel method of quantifying myocardial work (MW) with potential advantages over conventional global longitudinal strain (GLS) by incorporating measurements of myocardial deformation and LV pressure. We investigated different patterns of LV PSL and global MW index (GWI) in patients with hypertension (HTN) and dilated cardiomyopathy (CMP). Methods and results Seventy-four patients underwent transthoracic echocardiography and strain analysis before coronary angiography. Patients were divided into three groups: control, HTN, and CMP. GWI was calculated as the area of the LV PSL as a product of strain × systolic blood pressure. MW efficiency (GWE) is derived from the percentage ratio of constructive work (GCW) to sum of constructive work (GCW) and wasted work (GWW). Influences of HTN and LV function on its relationship with MW were evaluated. GLS and LV ejection fraction were preserved in the HTN group with no difference from controls. GWI was significantly higher in moderate to severe HTN patients (P = 0.004) as a compensatory mechanism to preserve LV contractility and function against an increase in afterload. GWE was preserved in HTN patients due to the proportional increase in GCW and GWW. GLS, GWI, and GWE were significantly reduced in CMP (P < 0.05), with a trend in rightward shift and reduction in the LV PSL. Conclusion GWI is a potential new technique that allows better understanding of the relationship between LV remodelling and increased wall stress under different loading conditions.

Extracorporeal Shock Wave Therapy for Coronary Artery Disease: Relationship of Symptom Amelioration and Ischemia Improvement

Objective(s): The current management of coronary artery disease (CAD) relies on three major therapeutic options, namely medication, percutaneous coronary intervention (PCI), and coronary artery bypass grafting (CABG). However, severe CAD that is not indicated for PCI or CABG still bears a poor prognosis due to the lack of effective treatments. In 2006, extracorporeal cardiac shock wave (SW) therapy reported on human for the first time. This treatment resulted in better myocardial perfusion as evaluated by dipyridamole stress thallium scintigraphy, angina symptoms, and exercise tolerance. The aim of the present study was to investigate: myocardial perfusion images and evaluate the relationship between the ischemia improvement and symptom amelioration by SW therapy. Methods: We treated ten patients (i.e., nine males and one female) with cardiac SW therapy who had CAD but not indicated for PCI or CABG and aged 63–89 years old. After the SW therapy, all patients were followed up for three months to evaluate any amelioration of the myocardial ischemia based on symptoms, adenosine stress thallium scintigraphy, transthoracic echocardiography, and blood biochemical examinations. Results: The changes in various parameters were evaluated before and after cardiac SW therapy. The cardiac SW therapy resulted in a significant improvement in the symptoms as evaluated by the Canadian Cardiovascular Society [CCS] class score (P=0.016) and a tendency to improve in summed stress score (SSS) (P=0.068). However, no significant improvement was observed in the summed rest score (SRS), summed difference score (SDS), left ventricular wall motion score index (LVWMSI), N-terminal pro-brain natriuretic, and troponin I. The difference of CCS class score (ΔCCS) was significantly correlated with those of SSS (ΔSSS) and SDS (ΔSDS) (r=0.69, P=0.028 and r=0.70, P=0.025, respectively). There was no significant correlation between ΔCCS and other parameters. Furthermore, no significant difference was observed between the CCS improved and non-improved groups in terms of the baseline characteristics. Conclusion: The current study demonstrated the potential efficacy and safety of Cardiac SW therapy in CAD patients. As the findings indicated, symptom amelioration was associated with ischemia improvement by extracorporeal shock wave therapy for the CAD patients.

Folic acid supplementation improves vascular endothelial function, yet not skin blood flow during exercise in the heat, in patients with heart failure

Heart failure (HF) patients are susceptible to heat strain during exercise, secondary to blunted skin blood flow (SkBF) responses, which may be explained by impaired nitric oxide (NO)-dependent vasodilation. Folic acid improves vascular endothelial function and SkBF through NO-dependent mechanisms in healthy older individuals and patients with cardiovascular disease. We examined the effect of folic acid supplementation (5 mg/day for 6 wk) on vascular function [brachial artery flow-mediated dilation (FMD)] and SkBF responses [cutaneous vascular conductance (CVC)] during 60 min of exercise at a fixed metabolic heat production (300 ẆHprod) in a 30°C environment in 10 patients with HF (New York Heart Association Class I-II) and 10 healthy controls (CON). Serum folic acid concentration increased in HF [preintervention (pre): 1.4 ± 0.2; postintervention (post): 8.9 ± 6.7 ng/ml, P = 0.01] and CON (pre: 1.3 ± 0.6; post: 5.2 ± 4.9 ng/ml, P = 0.03). FMD improved by 2.1 ± 1.3% in HF ( P < 0.01), but no change was observed in CON postintervention ( P = 0.20). During exercise, the external workload performed on the cycle ergometer to attain the fixed level of heat production for exercise was similar between groups (HF: 60 ± 13; CON: 65 ± 20 external workload, P = 0.52). Increases in CVC during exercise were similar in HF (pre: 0.89 ± 0.43; post: 0.83 ± 0.45 au/mmHg, P = 0.80) and CON (pre: 2.01 ± 0.79; post: 2.03 ± 0.72 au/mmHg, P = 0.73), although the values were consistently lower in HF for both pre- and postintervention measurement intervals ( P < 0.05). These findings demonstrate that folic acid improves vascular endothelial function in patients with HF but does not enhance SkBF during exercise at a fixed metabolic heat production in a warm environment.