Exercise Testing and Stress Imaging in Valvular Heart Disease

Mitral regurgitation assessment by cardiovascular magnetic resonance imaging during continuous in-scanner exercise: a feasibility study

PURPOSE

Exercise imaging using current modalities can be challenging. This was patient focused study to establish the feasibility and reproducibility of exercise-cardiovascular magnetic resonance imaging (EX-CMR) acquired during continuous in-scanner exercise in asymptomatic patients with primary mitral regurgitation (MR).

METHODS

This was a prospective, feasibility study. Biventricular volumes/function, aortic flow volume, MR volume (MR-Rvol) and regurgitant fraction (MR-RF) were assessed at rest and during low- (Low-EX) and moderate-intensity exercise (Mod-EX) in asymptomatic patients with primary MR.

RESULTS

Twenty-five patients completed EX-CMR without complications. Whilst there were no significant changes in the left ventricular (LV) volumes, there was a significant increase in the LVEF (rest 63 ± 5% vs. Mod-EX 68 ± 6%;p = 0.01). There was a significant reduction in the right ventricular (RV) end-systolic volume (rest 68 ml(60-75) vs. Mod-EX 46 ml(39-59);p < 0.001) and a significant increase in the RV ejection fraction (rest 55 ± 5% vs. Mod-EX 65 ± 8%;p < 0.001). Whilst overall, there were no significant group changes in the MR-Rvol and MR-RF, individual responses were variable, with MR-Rvol increasing by ≥ 15 ml in 4(16%) patients and decreasing by ≥ 15 ml in 9(36%) of patients. The intra- and inter-observer reproducibility of LV volumes and aortic flow measurements were excellent, including at Mod-EX.

CONCLUSION

EX-CMR is feasible and reproducible in patients with primary MR. During exercise, there is an increase in the LV and RV ejection fraction, reduction in the RV end-systolic volume and a variable response of MR-Rvol and MR-RF. Understanding the individual variability in MR-Rvol and MR-RF during physiological exercise may be clinically important.

[Stress testing: a relevant examination in rhythmology]

In recent years, imaging techniques have improved enormously. This leads to a decrease in stress testing indication for diagnosis and management of coronary artery diseases. However, stress testing remains an indispensable diagnostic tool for assessing patients' physical activity and their circulatory behavior during exercise. Using stress testing helps to assess patients' heart rate behavior or even to detect or trigger cardiac arrhythmias, for example, assessment of chronotropic competency, tachycardia-triggering or detection of a sudden heart rate drop with relevant bradycardia. The present review focuses on the assessment of stress testing in rhythmology. Since abnormal findings, which may indicate the presence of coronary heart disease, may occur during exercise testing, relevant ischemic criteria are also briefly addressed.

ANMCO position paper: 2022 focused update of appropriate use criteria for multimodality imaging: aortic valve disease

This document addresses the evaluation of the Appropriate Use Criteria (AUC) of multimodality imaging in the diagnosis and management of aortic valve disease. The goal of this AUC document is to provide a comprehensive resource for multimodality imaging in the context of aortic valve disease, encompassing multiple imaging modalities. Clinical scenarios are developed in a simple way to illustrate patient presentations encountered in everyday practice.

The effect of treatment with pimobendan in dogs with preclinical mitral valve disease - a placebo-controlled double-blinded crossover study

Background

Pimobendan is a widely used medication for the treatment of dogs with congestive heart failure (CHF) and preclinical degenerative mitral valve disease (DMVD) with cardiomegaly. The benefit of a treatment in dogs with preclinical DMVD but without cardiomegaly has not yet been elucidated. Some positive effects concerning life quality and a decrease in cardiac biomarkers could be verified. This study aimed to further investigate these results using a placebo-controlled double-blinded crossover design. Out of a total of 15 dogs, eight were allocated to sequence-group AB, in which dogs received pimobendan (A) during the first treatment period and placebo (B) during the second period. Accordingly, sequence-group BA was treated first with placebo followed by pimobendan. Each treatment period lasted six months and included a baseline investigation and follow-ups after 90 and 180 days. The investigations included a questionnaire completed by the owners, echocardiographic examination, and measurements of NT-proBNP, cTnI and lactate before and after a standardised submaximal exercise test.

Results

NT-proBNP values decreased significantly during the treatment period with pimobendan, and the post-exercise increase was attenuated at day 180. No significant treatment effects could be verified for cTnI and lactate, neither pre- nor post-exercise. Left ventricular size decreased under treatment, whereas no significant changes in left atrial size were detected. The owners described their dogs under treatment with pimobendan as being more active at day 90 (11/15) and day 180 (12/15). Those animals treated with placebo were described as being more active at day 90 (2/15) and day 180 (5/15).

Conclusions

Pimobendan had reducing effects on the concentrations of pre- and post-exercise cardiac biomarkers and the size of the left ventricle in dogs with DMVD ACVIM B1. Exercise testing in addition to an assessment of cardiac biomarkers might improve the decision when to initiate pimobendan treatment in dogs with DMVD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-021-03014-5.

Updated knowledge and practical implementations of stress echocardiography in ischemic and non-ischemic cardiac diseases: an expert consensus of the Working Group of Echocardiography of the Hellenic Society of Cardiology

Stress echocardiography (SE) is a well-established and valid technique, widely-used for the diagnostic evaluation of patients with ischemic and non-ischemic cardiac diseases. This statement of the Echocardiography Working Group of the Hellenic Society of Cardiology summarizes the consensus of the writing group regarding the applications of SE, based on the expertise of their members and on a critical review of current medical literature. The main objectives of the consensus document include a comprehensive review of SE methodology and training, focusing on the preparation, the protocols used and the analysis of the SE images and an updated, evidence-based knowledge about SE applications on ischemic and non-ischemic heart diseases, such as in cardiomyopathies, heart failure and valvular heart disease.

Athletes with valvular heart disease and competitive sports: a position statement of the Sport Cardiology Section of the European Association of Preventive Cardiology

This article provides an overview of the recommendations from the Sports Cardiology section of the European Association of Preventive Cardiology on sports participation in individuals with valvular heart disease (VHD). The aim of these recommendations is to encourage regular physical activity including sports participation, with reasonable precaution to ensure a high level of safety for all affected individuals. Valvular heart disease is usually an age-related degenerative process, predominantly affecting individuals in their fifth decade and onwards. However, there is an increasing group of younger individuals with valvular defects. The diagnosis of cardiac disorders during routine cardiac examination often raises questions about on-going participation in competitive sport with a high dynamic or static component and the level of permissible physical effort during recreational exercise. Although the natural history of several valvular diseases has been reported in the general population, little is known about the potential influence of chronic intensive physical activity on valve function, left ventricular remodelling pulmonary artery pressure, and risk of arrhythmia. Due to the sparsity of data on the effects of exercise on VHD, the present document is largely based on clinical experience and expert opinion.

Assessment of exercise-induced changes in von Willebrand factor as a marker of severity of aortic stenosis

Background

Loss of high-molecular-weight multimers (HMWMs) of von Willebrand factor (vWF) occurs due to high shear stress in patients with aortic stenosis. As symptoms of aortic stenosis occur during exercise, measurement of vWF during exercise might identify patients with aortic stenosis of clinical importance. The aim of this pilot study is to evaluate whether vWF changes over time as a result of exercise in patients with asymptomatic moderate or severe aortic stenosis.

Methods

Ten subjects were analysed for changes in vWF by measuring HMWMs and closure time with adenosine diphosphate (CT-ADP). All subjects underwent a full stress test on a bicycle ergometer. At rest and at peak exercise, a transthoracic echocardiogram was performed. HMWMs and CT-ADP were assessed at baseline, during and after exercise.

Results

HMWMs and CT-ADP did not change significantly during exercise, p=0.45 and p=0.65, respectively. HMWMs and CT-ADP correlated well, Spearman's rho -0.621, p<0.001. HMWMs during peak exercise did not correlate with maximal velocity measured, p=0.21. CT-ADP during exercise correlated well with the maximal echocardiographic velocity over the aortic valve (AV), rho 0.82, p=0.04.

Conclusions

In a cohort of 10 patients with moderate or severe aortic stenosis, we observed no significant change in vWF biomarkers during exercise. Peak CT-ADP during exercise showed a good correlation with peak AV velocity measured with echo. Although CT-ADP is an easy test to perform and could be an alternative for peak AV velocity measured during exercise, our results suggest that it can only detect large changes in shear stress.

Multiscale simulation of the effects of atrioventricular block and valve diseases on heart performance

A new mathematical model of the cardiovascular system is proposed. The left ventricle is described by an axisymmetric multiscale model where myocardium is treated as an incompressible transversely isotropic medium with a realistic distribution of fibre orientation. Active tension and its regulation by Ca²⁺ ions are described by our recent kinetic model. A lumped parameter model is used for the simulation of blood circulation, in which the left and right atria and the right ventricle are described by a system of ordinary differential equations for active pressure-volume relationships. The stress and strain of the left ventricle myocardium were calculated by the finite element method implemented by the authors. The changes in the haemodynamics upon changes in preload of a healthy heart, upon physical exercise, and in case of atrioventricular block with different types of arrhythmias were simulated. To simulate the effect of stenosis or regurgitation of the aortic or mitral valves, the hydraulic and inertial flow resistances of the heart valves were set as functions of their orifice areas. The model reproduced a number of phenomena observed in clinical practice, including the classification of the severity of valve disease.

Hemodynamic Changes During Physiological and Pharmacological Stress Testing in Healthy Subjects, Aortic Stenosis and Aortic Coarctation Patients-A Systematic Review and Meta-Analysis

Introduction: Exercise testing has become a diagnostic standard in the evaluation and management of heart disease. While different methods of exercise and pharmacological stress testing exist, only little is known about their comparability. We aimed to assess hemodynamic changes during dynamic exercise, isometric exercise, and dobutamine stress testing at different stress intensities in healthy subjects and patients with aortic stenosis (AS) and aortic coarctation (CoA).

Methods: A systematic literature search (PROSPERO 2017:CRD42017078608) in MEDLINE of interventional trials was conducted to identify eligible studies providing evidence of changes in hemodynamic parameters under different stress conditions acquired by MRI or echocardiography. A random effects model was used to estimate pooled mean changes in hemodynamics.

Results: One hundred and twenty-eight study arms with a total of 3,139 stress-examinations were included. In healthy subjects/(where available) in AS, pooled mean changes (95% CIs) during light dynamic stress were 31.78 (27.82–35.74) bpm in heart rate (HR) and 6.59 (2.58–10.61) ml in stroke volume (SV). Changes during light pharmacological stress were 13.71 (7.87–19.56)/14.0 (9.82–18.18) bpm in HR, and 5.47 (0.3–10.63)/8.0 (3.82–12.18) ml in SV. Changes during light isometric stress were 18.44 (10.74–26.14)/5.0 (−1.17–11.17) bpm in HR and −4.17 (−14.37–6.03)/−4.0 (−16.43–8.43) ml in SV. Changes during moderate dynamic stress were 49.57 (40.03–59.1)/46.45 (42.63–50.27) bpm in HR and 11.64 (5.87–17.42) ml in SV. During moderate pharmacological stress, changes in HR were 42.83 (36.94–48.72)/18.66 (2.38–34.93) bpm and in SV 6.29 (−2.0–14.58)/13.11 (7.99–18.23) ml. During high intensity dynamic stress changes in HR were 89.31 (81.46–97.17)/55.32 (47.31–63.33) bpm and in SV 21.31 (13.42–29.21)/−0.96 (−5.27–3.35) ml. During high pharmacological stress, changes in HR were 53.58 (36.53–70.64)/42.52 (32.77–52.28) bpm, and in SV 0.98 (−9.32–11.27)/14.06 (−1.62–29.74) ml. HR increase and age were inversely correlated at high stress intensities. In CoA, evidence was limited to single studies.

Conclusion: This systematic review and meta-analysis presents pooled hemodynamic changes under light, moderate and high intensity exercise and pharmacological stress, while considering the potential influence of age. Despite limited availability of comparative studies, the reference values presented in this review allow estimation of the expected individual range of a circulatory response in healthy individuals and patients with AS and may contribute to future study planning and patient-specific models even when stress testing is contraindicated.

Exercise cardiac magnetic resonance imaging: a feasibility study and meta-analysis

Cardiac stress testing improves detection and risk assessment of heart disease. Magnetic resonance imaging (MRI) is the clinical gold-standard for assessing cardiac morphology and function at rest; however, exercise MRI has not been widely adapted for cardiac assessment because of imaging and device limitations. Commercially available magnetic resonance ergometers, together with improved imaging sequences, have overcome many previous limitations, making cardiac stress MRI more feasible. Here, we aimed to demonstrate clinical feasibility and establish the normative, healthy response to supine exercise MRI. Eight young, healthy subjects underwent rest and exercise cinematic imaging to measure left ventricular volumes and ejection fraction. To establish the normative, healthy response to exercise MRI we performed a comprehensive literature review and meta-analysis of existing exercise cardiac MRI studies. Results were pooled using a random effects model to define the left ventricular ejection fraction, end-diastolic, end-systolic, and stroke volume responses. Our proof-of-concept data showed a marked increase in cardiac index with exercise, secondary to an increase in both heart rate and stroke volume. The change in stroke volume was driven by a reduction in end-systolic volume, with no change in end-diastolic volume. These findings were entirely consistent with 17 previous exercise MRI studies (226 individual records), despite differences in imaging approach, ergometer, or exercise type. Taken together, the data herein demonstrate that exercise cardiac MRI is clinically feasible, using commercially available exercise equipment and vendor-provided product sequences and establish the normative, healthy response to exercise MRI.

Clinical use of submaximal treadmill exercise testing and assessments of cardiac biomarkers NT-proBNP and cTnI in dogs with presymptomatic mitral regurgitation

Exercise intolerance is the first symptom of heart disease. Yet an objective and standardised method in canine cardiology to assess exercise capacity in a clinical setting is lacking. In contrast, exercise testing is a powerful diagnostic tool in humans, providing valuable information on prognosis and impact of therapeutic intervention. To investigate whether an exercise test reveals differences between dogs with early stage mitral regurgitation (MR) and dogs without cardiac disease, 12 healthy beagles (healthy group, HG) and 12 dogs with presymptomatic MR (CHIEF B1 / B2, patient group, PG) underwent a six-stage submaximal exercise test (ET) on a motorised treadmill. They trotted in their individual comfort speed for three minutes per stage, first without incline, afterwards increasing it by 4% for every subsequent stage. Blood samples were taken at rest and during two 3-minute breaks in the course of the test. Further samples were taken after the completion of the exercise test and again after a 3-hour recovery period. Measured parameters included heart rate, lactate and the cardiac biomarkers N-terminal pro-B-Type natriuretic peptide and cardiac Troponin I. The test was performed again under the same conditions in the same dogs three weeks after the first trial to evaluate individual repeatability. Cardiac biomarkers increased significantly in both HG and PG in the course of the test. The increase was more pronounced in CHIEF B1 / B2 dogs than in the HG. N-terminal pro-B-Type natriuretic peptide increased from 435 ± 195 to 523 ± 239 pmol/L (HG) and from 690 to 815 pmol/L (PG). cTnI increased from 0.020 to 0.024 ng/mL (HG) and from 0.06 to 0.08 ng/ml (PG). The present study provides a method to assess exercise-induced changes in cardiac biomarkers under clinical conditions. The increase of NT-proBNP and cTnI is more pronounced in dogs with early-stage MR than in healthy dogs. Results indicate that measuring the parameters before and after exercise is adequate and taking blood samples between the different stages of the ET does not provide additional information. Also, stress echocardiography was inconclusive. It can be concluded that exercise testing, especially in combination with measuring cardiac biomarkers, could be a helpful diagnostic tool in canine cardiology.

Postnatal undernutrition in mice causes cardiac arrhythmogenesis which is exacerbated when pharmacologically stressed

Growth restriction caused by postnatal undernutrition increases risk for cardiovascular disease in adulthood with the potential to induce arrhythmogenesis. Thus, the purpose was to determine if undernutrition during development produced arrhythmias at rest and when stressed with dobutamine in adulthood. Mouse dams were fed (CON: 20% protein), or low-protein (LP: 8%) diet before mating. A cross-fostering model was used where pups nursed by dams fed LP diet in early [EUN; postnatal day (PN) 1–10], late (LUN; PN11–21) and whole (PUN; 1–21) phases of postnatal life. Weaned pups were switched to CON diets for the remainder of the study (PN80). At PN80, body composition (magnetic resonance imaging), and quantitative electrocardiogram (ECG) measurements were obtained under 1% isoflurane anesthesia. After baseline ECG, an IP injection (1.5 µg/g body weight) of dobutamine was administered and ECG repeated. Undernutrition significantly (P<0.05) reduced body weight in LUN (22.68±0.88 g) and PUN (19.96±0.32 g) but not in CON (25.05±0.96 g) and EUN (25.28±0.9207 g). Fat mass decreased in all groups compared with controls (CON: 8.00±1.2 g, EUN: 6.32±0.65 g, LUN: 5.11±1.1 g, PUN: 3.90±0.25 g). Lean mass was only significantly reduced in PUN (CON: 17.99±0.26 g, EUN: 17.78±0.39 g, LUN: 17.34±0.33 g, PUN: 15.85±0.28 g). Absolute heart weights were significantly less from CON, with PUN having the smallest. ECG showed LUN had occurrences of atrial fibrillation; EUN had increases of 1st degree atrioventricular block upon stimulation, and PUN had increased risk for ventricular depolarization arrhythmias. CON did not display arrhythmias. Undernutrition in early life resulted in ventricular arrhythmias under stressed conditions, but undernutrition occurring in later postnatal life there is an increased incidence of atrial arrhythmias.

Decreases in left atrial compliance during early-stage exercise are related to exercise intolerance in asymptomatic significant mitral stenosis

BACKGROUND

Doppler-driven net atrioventricular compliance (C_n ), which represents left atrial (LA) compliance, is an important determinant of pulmonary hypertension in mitral stenosis (MS).

HYPOTHESIS

We hypothesized that decreases in C_n during early-stage exercise underlie exercise intolerance in patients with MS.

METHODS

Thirty-three asymptomatic patients with significant MS (valve area 1.24 ± 0.16 cm² ) underwent resting and bicycle exercise echocardiography. LA compliance and conventional parameters were assessed at each workload. The patients were classified into two groups based on whether they developed dyspnea during exercise: an exercise-intolerance group (n = 22) and an exercise-tolerance group (n = 11). Moreover, "50 W" was defined as an early exercise stage.

RESULTS

Although the groups had similar resting characteristics, there were striking differences in their echocardiographic parameters from the early stages of exercise. The relative C_n decrease at 50 W (expressed as a percentage of the resting C_n ) was significantly greater in the exercise-intolerance group (70.3 ± 15.4% vs 49.7 ± 9.7%, P < .001). The overall decrease in relative C_n was significantly greater in the exercise-intolerance group (P = .0005). Furthermore, differences in the trends in this parameter were observed between the two groups (P < .0001 for interaction). Multivariate analysis revealed that the relative C_n decrease at 50 W was an independent predictor of exercise intolerance (adjusted OR 1.105, 95% CI 1.030-1.184) after adjustment for other conventional parameters.

CONCLUSIONS

Decreases in C_n during early-stage exercise are an important mechanism underlying exercise intolerance in MS.

Self-reported health status, treatment decision and survival in asymptomatic and symptomatic patients with aortic stenosis in a Western Norway population undergoing conservative treatment: a cross-sectional study with 18 months follow-up

OBJECTIVES

To investigate symptoms and self-reported health of patients conservatively treated for aortic stenosis (AS) and to identify factors associated with treatment decision and patient outcomes.

DESIGN

A cross-sectional survey with an 18-month follow-up.

SETTING

One tertiary university hospital in Western Norway.

PARTICIPANTS

In all, 1436 patients were diagnosed with AS between 2000 and 2012, and those 245 still under conservative treatment in 2013 were included in this study.

PRIMARY AND SECONDARY OUTCOME MEASURES

Primary outcome measures were symptoms and self-reported health status. Secondary outcomes were treatment decision and patient survival after 18 months.

RESULTS

A total of 136 patients with mean (SD) age 79 (12) years, 52% men responded. Among conservatively treated patients 77% were symptomatic. The symptom most frequently experienced was dyspnoea. Symptomatic patients reported worse physical and mental health compared with asymptomatic patients (effect size 1.24 and 0.74, respectively). In addition, symptomatic patients reported significantly higher levels of anxiety and depression compared with asymptomatic patients. However, symptom status did not correlate with haemodynamic severity of AS. After 18 months, 117 (86%) were still alive, 20% had undergone surgical aortic valve replacement (AVR) and 7% transcatheter aortic valve implantation (TAVI). When adjusting for age, gender, symptomatic status, severity of AS and European system for cardiac operative risk evaluation (EuroSCORE), patients with severe AS had more than sixfold chance of being scheduled for AVR or TAVI compared with those with moderate AS (HR 6.3, 95% CI 1.9 to 21.2, p=0.003). Patients with EuroSCORE ≥11 had less chance for undergoing AVR or TAVI compared with those with EuroSCORE ≤5 (HR 0.06, 95% CI 0.01 to 0.46, p=0.007).

CONCLUSIONS

Symptoms affected both physical and mental health in conservatively treated patients with AS. Many patients with symptomatic severe AS are not scheduled for surgery, despite the recommendations in current guidelines. The referral practice for AVR is a path for further investigation.

The Role of Stress Echocardiography in Valvular Heart Disease: A Current Appraisal

Stress echocardiography is a widely available, safe, low-cost, versatile imaging modality which is becoming increasingly recognized as a valuable tool in the assessment of patients with native and prosthetic left-sided valvular heart disease. It provides a quantitative assessment to help guide clinical decision-making when discordance exists between symptoms and severity of valve disease. Exercise (treadmill or bicycle) remains the preferred stress modality, but pharmacological augmentation with dobutamine can be used if needed. Low-dose dobutamine stress echocardiography is specifically valuable in patients with low-flow, low-gradient aortic stenosis when attempting to differentiate true severe aortic stenosis from pseudo-severe aortic stenosis. Stress echocardiography not only identifies high-risk features that indicate need for earlier surgery, it also provides useful information for the peri- and postoperative period, including long-term outcome, risk stratification to guide monitoring frequency, and offers guidance for eligibility in competitive sports participation. As research continues to expand the utility of stress echocardiography in the management of patients with valvular heart disease, future research should focus on the recognition of newer parameters identifying high-risk features including subsequent validation in a large population.

Interrupted commissural band annuloplasty prevents mitral stenosis

BACKGROUND

Mitral annuloplasty is an important component of the treatment of degenerative mitral valve disease. However, postoperative echocardiography reveals elevated mitral gradients in some patients. We developed a technique that we termed interrupted commissural band annuloplasty (iCBA), which does not shorten either the anterior or posterior annulus and is not associated with the development of a mitral gradient. We compared the echocardiographic characteristics of patients treated using this method versus Cosgrove ring (COS) placement, both at rest and during exercise.

METHODS

ICBA features placement of three sutures in the commissures using two bands and shortens the commissural annular length by 60 %. We used this method to treat 63 patients and placed Cosgrove bands in 58. Of all patients, 48 who underwent iCBA and 34 with COSs passed the exercise echocardiographic test.

RESULTS

The maximal transmitral pressures at rest in the iCBA and Cosgrove groups were 8.04 ± 0.74 and 11.30 ± 0.88 mmHg (P = 0.0029), respectively, and the mean transmitral pressures at rest were 2.46 ± 0.74 and 3.61 ± 0.32 mmHg (P = 0.0037), respectively. The maximal transmitral pressures during exercise were 11.79 ± 0.97 and 18.37 ± 1.16 mmHg (P < 0.0001), and the mean transmitral pressures during exercise were 4.95 ± 0.45 and 7.76 ± 0.53 mmHg (P < 0.0001).

CONCLUSIONS

ICBA prevents postoperative mitral stenosis both at rest and importantly during exercise.

2016 Focused Update: Clinical Recommendations for Cardiopulmonary Exercise Testing Data Assessment in Specific Patient Populations

In the past several decades, cardiopulmonary exercise testing (CPX) has seen an exponential increase in its evidence base. The growing volume of evidence in support of CPX has precipitated the release of numerous scientific statements by societies and associations. In 2012, the European Association for Cardiovascular Prevention & Rehabilitation and the American Heart Association developed a joint document with the primary intent of redefining CPX analysis and reporting in a way that would streamline test interpretation and increase clinical application. Specifically, the 2012 joint scientific statement on CPX conceptualized an easy-to-use, clinically meaningful analysis based on evidence-vetted variables in color-coded algorithms; single-page algorithms were successfully developed for each proposed test indication. Because of an abundance of new CPX research in recent years and a reassessment of the current algorithms in light of the body of evidence, a focused update to the 2012 scientific statement is now warranted. The purposes of this update are to confirm algorithms included in the initial scientific statement not requiring revision, to propose revisions to algorithms included in the initial scientific statement, to propose new algorithms based on emerging scientific evidence, to further clarify the application of oxygen consumption at ventilatory threshold, to describe CPX variables with an emerging scientific evidence base, to describe the synergistic value of combining CPX with other assessments, to discuss personnel considerations for CPX laboratories, and to provide recommendations for future CPX research.

Principles of transthoracic echocardiographic evaluation

Transthoracic echocardiography is the most widely used imaging test in cardiology. Although completely noninvasive, transthoracic echocardiography has a well-established role in the diagnosis of numerous cardiovascular diseases, and also provides critical qualitative and quantitative information on their prognosis and pathophysiological processes. The aim of this Review is to outline the broad principles of transthoracic echocardiography, including the traditional techniques of two-dimensional, colour, and spectral Doppler echocardiography, and newly developed advances including tissue Doppler, myocardial deformation imaging, torsion, stress echocardiography, contrast and three-dimensional echocardiography. The advantages and disadvantages, clinical application, prognostic value, and salient research findings of each modality are described. Advances in complex imaging techniques are expected to continue unabated, and this Review highlights technical improvements that will influence the diagnosis and improve our understanding of cardiovascular function and disease.