Pulmonary hypertension is defined as a mean arterial pressure of ≥25 mmHg as confirmed on right heart catheterisation. Traditionally, the pulmonary arterial systolic pressure has been estimated on echo by utilising the simplified Bernoulli equation from the peak tricuspid regurgitant velocity and adding this to an estimate of right atrial pressure. Previous studies have demonstrated a correlation between this estimate of pulmonary arterial systolic pressure and that obtained from invasive measurement across a cohort of patients. However, for an individual patient significant overestimation and underestimation can occur and the levels of agreement between the two is poor. Recent guidance has suggested that echocardiographic assessment of pulmonary hypertension should be limited to determining the probability of pulmonary hypertension being present rather than estimating the pulmonary artery pressure. In those patients in whom the presence of pulmonary hypertension requires confirmation, this should be done with right heart catheterisation when indicated. This guideline protocol from the British Society of Echocardiography aims to outline a practical approach to assessing the probability of pulmonary hypertension using echocardiography and should be used in conjunction with the previously published minimum dataset for a standard transthoracic echocardiogram.
The structure and function of the right side of the heart is influenced by a wide range of physiological and pathological conditions. Quantification of right heart parameters is important in a variety of clinical scenarios including diagnosis, prognostication, and monitoring response to therapy. Although echocardiography remains the first-line imaging investigation for right heart assessment, published guidance is relatively sparse in comparison to that for the left ventricle. This guideline document from the British Society of Echocardiography describes the principles and practical aspects of right heart assessment by echocardiography, including quantification of chamber dimensions and function, as well as assessment of valvular function. While cut-off values for normality are included, a disease-oriented approach is advocated due to the considerable heterogeneity of structural and functional changes seen across the spectrum of diseases affecting the right heart. The complex anatomy of the right ventricle requires special considerations and echocardiographic techniques, which are set out in this document. The clinical relevance of right ventricular diastolic function is introduced, with practical guidance for its assessment. Finally, the relatively novel techniques of three-dimensional right ventricular echocardiography and right ventricular speckle tracking imaging are described. Despite these techniques holding considerable promise, issues relating to reproducibility and inter-vendor variation have limited their clinical utility to date.
Since cardiac ultrasound was introduced into medical practice around the middle twentieth century, transthoracic echocardiography has developed to become a highly sophisticated and widely performed cardiac imaging modality in the diagnosis of heart disease1. This evolution from an emerging technique with limited application, into a complex modality capable of detailed cardiac assessment has been driven by technological innovations that have both refined ‘standard’ two dimensional and Doppler imaging and led to the development of new diagnostic techniques. Accordingly, the adult transthoracic echocardiogram has evolved to become a comprehensive assessment of complex cardiac anatomy, function and haemodynamics. This guideline protocol from the British Society of Echocardiography aims to outline the minimum dataset required to confirm normal cardiac structure and function when performing a comprehensive standard adult echocardiogram and is structured according to the recommended sequence of acquisition. It is recommended that this structured approach to image acquisition and measurement protocol forms the basis of every standard adult transthoracic echocardiogram. However, when pathology is detected and further analysis becomes necessary, views and measurements in addition to the minimum dataset are required and should be taken with reference to the appropriate British Society of Echocardiography imaging protocol. It is anticipated that the recommendations made within this guideline will help standardise the local, regional and national practice of echocardiography, in addition to minimising the inter and intra-observer variation associated with echocardiographic measurement and interpretation.
The purpose of this study was twofold: 1) to investigate the feasibility and usefulness of cardiac microdialysis for the simultaneous estimation of regional cardiac interstitial fluid (ISF) adenosine (ADO) concentration and coronary blood flow (CBF); and 2) to determine the changes in the ISF levels of ADO and CBF during cardiac stimulation or regional myocardial ischemia. Cardiac microdialysis probes were implanted in the left ventricular myocardium of chloralose-urethan-anesthetized dogs and perfused with Krebs-Henseleit buffer. The concentration of ADO in the effluent dialysate was used as an index of intramyocardial ISF ADO concentration while local CBF was measured by H2 clearance via a platinum wire within the dialysis fiber. Dialysate ADO was elevated immediately after insertion of the microdialysis probe, declined rapidly in the first 20 min, stabilized by 60 min, and remained constant for 2 h. Based on the relationship in vitro and in vivo between microdialysis probe perfusion rate and dialysate ADO concentration, ISF ADO concentration within the left ventricular myocardium was estimated to be 0.9-1.3 microM. Dobutamine (10 micrograms.kg-1.min-1) infusion resulted in a 36% increase in CBF and a 2.5-fold increase in dialysate ADO (n = 9; P less than 0.05). Regional myocardial ischemia, induced by occlusion of the left anterior descending artery (LAD), caused a 13-fold increase in dialysate ADO in the LAD perfused myocardium (n = 9; P less than 0.05). These results are consistent with the ADO hypothesis and suggest that cardiac microdialysis provides a reliable technique for the sampling of regional intramyocardial ISF.
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