Recent advances in stress echocardiography

Donor heart selection: Evidence-based guidelines for providers

The proposed donor heart selection guidelines provide evidence-based and expert-consensus recommendations for the selection of donor hearts following brain death. These recommendations were compiled by an international panel of experts based on an extensive literature review.

Cardiopulmonary Capacity in Children During Exercise Testing: The Differences Between Treadmill and Upright and Supine Cycle Ergometry

Background/Hypothesis: Cardiopulmonary exercise testing (CPET) is used in the assessment of function and prognosis of cardiopulmonary health in children with cardiac and pulmonary diseases. Techniques, such as cardiac MRi, and PET-scan, can be performed simultaneously with exercise testing. Thus, it is desirable to have a broader knowledge about children’s normal cardiopulmonary function in different body postures and exercise modalities. The aim of this study was to investigate the effect of different body positions on cardiopulmonary function in healthy subjects performing CPETs.

Materials and Methods: Thirty-one healthy children aged 9, 12, and 15 years did four CPETs: one treadmill test with a modified Bruce protocol and three different bicycle tests with different body postures, sitting, tilted 45°, and lying flat (0°). For the bicycle tests, a 20-watt ramp protocol with a pedal frequency of 60 ± 5 rotations per minute was used. Continous ECG and breath-by-breath V.O2 measurements was done throughout the tests. Cardiac structure and function including aortic diameter were evaluated by transthoracic echocardiography prior to the tests. Doppler measurements of the blood velocity in the ascending aorta were measured prior to and during the test. Prior to every test, the participants performed pulmonary function tests with maximum voluntary ventilation test.

Results: There is a significantly (p < 0.05) lower peak V.O2 in all bicycle tests compared with the treadmill test. There is lower corrected peak V.O2 (ml kg^−0.67 min⁻¹), but not relative peak V.O2 (ml kg⁻¹ min⁻¹), in the supine compared with the upright bicycle test. There are no differences in peak stroke volume or cardiac output between the bicycle modalities when calculated from aortic blood flow. Peak heart rate decreases from both treadmill to upright bicycle and from upright bicycle to the supine test (0°).

Conclusion: There are no differences in peak cardiac output between the upright bicycle test and supine bicycle tests. Heart rate and corrected peak V.O2 are lower in the supine test (0°) than the upright bicycle test. In the treadmill test, it is a higher absolute and relative peak V.O2. Despite the latter differences, we are convinced that both upright and supine bicycle tests are apt in the clinical setting when needed.

Four-dimensional echocardiography area strain combined with exercise stress echocardiography to evaluate left ventricular regional systolic function in patients with mild single vessel coronary artery stenosis

BACKGROUND

The aim of this prospective study was to assess the diagnosis value of four-dimensional echocardiography area strain (AS) combined with exercise stress echocardiography to evaluate left ventricular regional systolic function in patients with mild single vessel coronary artery stenosis.

METHODS

Based on treadmill exercise load status, two-dimensional conventional echocardiography and four-dimensional echocardiography area strain were performed on patients suspected coronary artery disease before coronary angiogram. Thirty patients (case group) with mild left anterior descending coronary artery stenosis (stenosis <50%) and thirty gender- and age-matched patients (control group) without coronary artery stenosis according to the coronary angiogram results were prospectively enrolled.

RESULTS

All the patients had no left ventricular regional wall motion abnormality in two-dimensional echocardiography at rest and exercise stress. There was no significant difference in the 16 segmental systolic peak AS at rest between two groups. After exercise stress, the peak systolic AS_rest-stress at mid anterior wall (-7.00%±10.90% vs 2.80%±23.69%) and mid anterolateral wall (-4.40%±18.81% vs 8.80%±19.16%) were decreased, while increased at basal inferolateral wall (14.00%±19.27% vs -5.60%±15.94%) in case group compared with control group (P<.05).

CONCLUSIONS

In patients with mild single vessel coronary artery stenosis, the area strain was decreased at involved segments, while compensatory increased at noninvolved segments after exercise stress. Four-dimensional echocardiography area strain combined with exercise stress echocardiography could sensitively find left ventricular regional systolic function abnormality in patients with mild single vessel coronary artery stenosis, and locate stenosis coronary artery accordingly.

Global Deformation Parameters Response to Exercise in Adolescents with Repaired Tetralogy of Fallot

Exercise stress echocardiography is rarely used in the follow-up of children with congenital heart disease following surgical repair. There are no data on global longitudinal strain (GLS) and global circumferential strain (GCS) during exercise in adolescents with repaired tetralogy of Fallot (TOF). The purpose of this prospective study was to investigate GLS and GCS using speckle tracking two-dimensional echocardiography (2D-STE) at rest and during exercise in adolescents with repaired TOF. Twenty patients with repaired TOF and 20 controls were included. The subjects exercised on a semi-supine cycle ergometer using a two-staged 3-min step protocol of 20-40 W at 60-75 rpm. Exercise images with 2D-STE measurements were available for all 40 subjects. In the study group, the GLS values changed significantly between the baseline and third and sixth minute of exercise (-18.10 ± 2.20, -16.23 ± 4.47, -14.22 ± 2.63, respectively, p < 001). GCS did not vary significantly from baseline to end of the exercise testing (-17.49 ± 5.14, -17.15 ± 9.20, -15.66 ± 3.59, respectively, p > 0.05). There was a statistically significant difference between the Stage I longitudinal strain values of the study and control groups (-14.26 ± 9.13 and -20.22 ± 2.88, respectively, p = 0.02) but no significant difference between the Stage II values of these groups (-14.22 ± 2.63 and -15.11 ± 2.45, respectively, p > 0.05). The results revealed significant changes in GLS during exercise in patients with repaired TOF. Data gathered from deformation analysis of 2D-STE during exercise testing can enhance the ability to detect subtle ventricular dysfunction in the follow-up of children with repaired TOF.

Coronary calcification with no flow limiting lesions: A potential cause for ischaemic dysfunction in syndrome X patients

Aim

Exertional angina in patients with no coronary flow limiting lesions remains a clinical puzzle. We aimed to assess the extent of coronary artery calcification (CAC) and its relationship to ventricular wall motion function using stress echocardiography in a group of patients limited by exertional angina, but no obstructive lesions.

Methods

We compared CT coronary calcium score (CACS) and dobutamine stress echocardiography in 55 patients (age 64.7 ± 7.7 years), divided into Group 1 (CACS ≤ 100) and Group 2 (CACS > 100). No patient had LV ejection fraction-EF < 55%, pulmonary hypertension, arrhythmia, renal failure or parathyroid disease. Multiple linear regression analysis was used to test the association between gender-standardized continuous echocardiographic parameters and patient groups adjusted for age, body surface area, osteoporosis and CV risk factors and CACS.

Results

At rest, LV long axis ‘subendocardial’ function was reduced (amplitude: β − 1.11 SD, p < 0.05, R² 0.6 and systolic velocity: β − 1.08 SD, p < 0.05, R² 0.44), left atrial (LA) indexed volume was raised (β 1.06 SD, p < 0.05, R² 0.37) and its systolic velocity decreased (β − 1.05 SD, p < 0.05, R² 0.35) in Group 2. With stress, wall motion score index increased (p < 0.05) and long axis disturbances worsened only in the same group. Multivariate analysis demonstrated clear relationship between ischaemic LV disturbances, reduced long axis amplitude, global longitudinal systolic strain and early diastolic strain rate. Resting and stress RV lengthening velocity also correlated with CAC score.

Conclusion

In symptomatic patients with no obstructive coronary lesions and with more than mild CAC, long axis disturbances and wall motion score index rise occur with stress, at the time of symptom development and correlate with severity of arterial calcification. These findings suggest CAC as a potential mechanism for coronary wall stiffness and consequently exertional ischaemic changes as a result of limited flow reserve.

Stress-echocardiography is underused in clinical practice: a nationwide survey in Austria

BACKGROUND

The wide area of application, including coronary artery disease, valvular heart disease, or pulmonary hypertension makes stress echocardiography (SE) a powerful, cost-effective imaging modality in cardiology. The role of this technique in clinical practice in Austria is unknown.

METHODS

A nationwide survey included all departments for cardiology and/or internal medicine in the years 2008 and 2013. By electronic questionnaire demographics, indication for the test, the numbers of examined cases per year, operators, and various applied techniques of SE were interrogated and completed by telephone interviews.

RESULTS

Data could be obtained from all 117 departments. In the year 2007 in 58 (50%) and in 2012 57 (49%) departments SE was available in Austrian hospitals. More than 100 SEs per year were performed by only four (7%) units in the year 2007 and by five (8%) in 2012. Physical exercise, dobutamine, and dipyridamole SE were available in 27 (46%), 52 (90%), and six (10%) units in 2007, and in 15 (27%), 52 (91%), and five (9%) units in 2012, respectively. In 2007 41 (71%) and in 2012 26 (46%) echo-labs administered contrast agents during SE. Transesophageal SE and 3D-echo was performed in one (2%) and three (5%) units in 2007, and in six (10%) and four (7%) echo-labs in 2012.

CONCLUSIONS

This representative survey demonstrates the underuse of SE in clinical practice in Austria. Even in established application fields performance is low, examination frequencies as recommended by the cardiology societies are fulfilled only by a minority of institutions.

Semi-supine exercise stress echocardiography in children and adolescents: feasibility and safety

Although exercise stress echocardiography (ESE) is a well-validated technique in adult population, its use in children is quite limited. We aimed to assess the feasibility, the safety and the reproducibility of ESE, using on-line scanning in semi-supine cyclo-ergometer protocol in a large pediatric population. Between July 2008 and January 2013, 42 patients (mean age 14 ± 3) were evaluated with a bicycle ESE performing 50 studies. ESE was successfully performed and well tolerated by all patients. None of the patients presented with adverse effects of stress-induced ischemia. HR was 82 ± 13 at rest, and 153 ± 19.1 during peak exercise. Among 544 views analyzed for grading of image quality, the visualization was optimal in 473 (87 %), suboptimal in 39, and inadequate in 32 (6 %). 37 tests were performed in patients with congenital or acquired coronary abnormality. Regional wall motion abnormalities (RWMA) were revealed in nine cases (24 %). The agreement between the two different observers showed a K index of 0.7276 (95 % CI 0.6497-0.8055) for the image quality and a K index of 0.5125 (95 % CI 0.4782-0.5468) for the RWMA analysis. Among ten patients with hypertrophic cardiomyopathy, we were able to demonstrate the new comparison of significant left ventricular outflow tract gradient (≥30 mmHg) during exercise in three patients (30 %). Bicycle stress echocardiography performed by on-line scanning during exercise is a feasible, safe, and reproducible modality in children. Further data to assess its diagnostic accuracy are, however, needed. Stress echocardiography provides a dynamic assessment of the myocardial structure and function under conditions of physiologic or pharmacologic stress.

Medium-term outcome of recipients of marginal donor hearts selected with new stress-echocardiographic techniques over standard criteria

BACKGROUND

Heart transplantation is limited by severe donor organ shortage. Regardless of the changes made in the acceptance of marginal donors, any such mechanism cannot be considered successful unless recipient graft survival rates remain acceptable. A stress echo-driven selection of donors has proven successful in older donors with normal left ventricular resting function and in standard donors with reversible resting left ventricular dysfunction acutely improving during stress, or slowly improving (over hours) during intensive hormonal treatment. Aim of this study is to assess the medium-term outcome of recipients of marginal donor hearts selected with new echocardiographic techniques over standard criteria.

METHODS AND RESULTS

We enrolled 43 recipients of marginal donor hearts: age > 55 years, or < 55 years but with concomitant risk factors, n = 32; acutely improving during stress, n = 3; or slowly improving during hormonal treatment, n = 8. At follow-up (median, 30 months; interquartile range, 21-52 months), 37 of the recipients were still alive. One-year survival was 93%.

CONCLUSION

The strict use of new stress-echocardiographic techniques over standard criteria of marginal donor management, together with comprehensive monitoring of the donor, has the potential to substantially increase the number of donor hearts without adverse effects on recipient medium-term outcome.

Transplant of stunned donor hearts rescued by pharmacological stress echocardiography: a "proof of concept" report

Background

Due to the shortage of donor hearts, the criteria for acceptance have been considerably expanded. Hearts with regional or global left ventricular dysfunction are excluded from donation, but stress echo might be useful to identify patients with reversible wall motion abnormalities, potentially eligible for donation.

Methods

Six marginal candidate donors (mean age, 40 ± 13 years; three men) were enrolled. Resting echocardiography showed in all subjects a LV ejection fraction ≥ 45% (mean 51 ± 5%), but multiple risk factors were present. All donors had either global or discrete wall motion abnormalities: Wall Motion Score Index (WMSI) rest = 1.33 ± 0.25. Stress echocardiography was performed with the dipyridamole high dose of 0.84 mg/kg given over 6 min.

Results

The stress echo results were abnormal in three donors (WMSI rest = 1.51 ± 0.19 vs peak = 1.41 ± 0.30). These hearts were excluded from donation and cardiac pathology verification was available in two cases of confirmed LV myocardial fibrosis and/or severe coronary stenosis. The remaining three hearts improved during stress (WMSI rest = 1.15 ± 0.13 vs peak = 1.04 ± 0.06) and were transplanted uneventfully. Recipients (three males, mean age 53 ± 4 years) underwent post-TX coronary angiography, IVUS and endomyocardial biopsies. No recipient had primary graft failure, and all showed normal coronary angiography and normal LV function (EF = 57 ± 6%; WMSI = 1 ± 0) at 1-month post-TX. The recipients were alive at 12-month median follow-up.

Conclusions

Dipyridamole stress echo performed in brain-dead potential donors with LV resting global or discrete wall motion abnormalities identifies hearts with severe morphologic abnormalities excluded from donation (with fixed response during stress echo) from hearts eligible for donation, showing improvement in regional wall motion during stress (viability response) and normal function and coronary anatomy following transplantation.

New concept of myocardial longitudinal strain reserve assessed by a dipyridamole infusion using 2D-strain echocardiography: the impact of diabetes and age, and the prognostic value

AIMS

Although dipyridamole is a widely used pharmacological stress agent, the direct effects on myocardium are not entirely known. Diabetic cardiomyopathy can be investigated by 2D-strain echocardiography. The aim of this study was to assess myocardial functional reserve after dipyridamole infusion using speckle-tracking echocardiography.

METHODS

Seventy-five patients referred for dipyridamole stress myocardial perfusion gated SPECT (MPGS) were examined by echocardiography to assess a new concept of longitudinal strain reserve (LSR) and longitudinal strain rate reserve (LSRR) respectively defined by the differences of global longitudinal strain (GLS) and longitudinal strain rate between peak stress after dipyridamole and rest. Twelve patients with myocardial ischemia were excluded on the basis of MPGS as gold standard.

RESULTS

Mean LSR was -2.28±2.19% and was more important in the 28 (44%) diabetic patients (-3.27±1.93%; p=0.001). After multivariate analyses, only diabetes improved LSR (p=0.011) after dipyridamole infusion and was not associated with glycaemic control (p=0.21), insulin therapy (p=0.46) or duration of the disease (p=0.80). Conversely, age (p=0.002) remained associated with a decrease in LSR. LSSR was also correlated to age (p=0.005). Patients with a LSR<0% have a better survival after 15 months (log-rank p=0.0012).

CONCLUSION

LSR explored by 2D speckle-tracking echocardiography after dipyridamole infusion is a simple and new concept that provides new insights into the impact of diabetes and age on the myocardium with a potential prognostic value.