Assessment of left ventricular function by three-dimensional echocardiography.

Accurate determination of LV volume, ejection fraction and segmental wall motion abnormalities is important for clinical decision-making and follow-up assessment. Currently, echocardiography is the most common used method to obtain this information. Three-dimensional echocardiography has shown to be an accurate and reproducible method for LV quantitation, mainly by avoiding the use of geometric assumptions. In this review, we describe various methods to acquire a 3D-dataset for LV volume and wall motion analysis, including their advantages and limitations. We provide an overview of studies comparing LV volume and function measurement by various gated and real-time methods of acquisition compared to magnetic resonance imaging. New technical improvements, such as automated endocardial border detection and contrast enhancement, will make accurate on-line assessment with little operator interaction possible in the near future

Strain analysis is superior to wall thickening in discriminating between infarcted myocardium with and without microvascular obstruction

Objectives: The aim of the present study was to evaluate the diagnostic performances of strain and wall thickening analysis in discriminating among three types of myocardium after acute myocardial infarction: non-infarcted myocardium, infarcted myocardium without microvascular obstruction (MVO) and infarcted myocardium with MVO. Methods: Seventy-one patients with a successfully treated ST-segment elevation myocardial infarction underwent cardiovascular magnetic resonance imaging at 2-6 days after reperfusion. The imaging protocol included conventional cine imaging, myocardial tissue tagging and late gadolinium enhancement. Regional circumferential and radial strain and associated strain rates were analyzed in a 16-segment model as were the absolute and relative wall thickening. Results: Hyperenhancement was detected in 418 (38%) of 1096 segments and was accompanied by MVO in 145 (35%) of hyperenhanced segments. Wall thickening, circumferential and radial strain were all significantly diminished in segments with hyperenhancement and decreased even further if MVO was also present (all p < 0.001). Peak circumferential strain (CS) surpassed all other strain and wall thickening parameters in its ability to discriminate between hyperenhanced and non-enhanced myocardium (all p < 0.05). Furthermore, CS was superior to both absolute and relative wall thickening in differentiating infarcted segments with MVO from infarcted segments without MVO (p = 0.02 and p = 0.001, respectively). Conclusions: Strain analysis is superior to wall thickening in differentiating between non-infarcted myocardium, infarcted myocardium without MVO and

Magnetic resonance imaging of the right ventricle in human pulmonary hypertension

Pulmonary Hypertension (PH) is a rare but devastating illness which results in progressive right ventricular (RV) failure and early death. RV function determines survival in all patients with PH but it is difficult to measure accurately using existing clinical techniques. The choice and design of the experiments in this thesis was driven by a desire to improve our understanding of the reasons for right, and left,ventricular dysfunction in this context. Cardiovascular magnetic resonance (CMR)imaging was utilized throughout as it allows the non-invasive, direct and accurate study of both ventricles; at rest and during stress. In Chapter 3, CMR imaging was used to identify an NT-proBNP threshold (1685 ng/l, sensitivity 100%, specificity 94%) for the non-invasive detection of RV systolic dysfunction in patients with PH. In Chapter 4, contrast-enhanced-CMR was utilized for the first time in PH patients and revealed previously unidentified areas of myocardial fibrosis within the RV insertion points and interventricular septum. The extent of these areas correlated inversely with RV ejection fraction (r = -0.762, p < 0.001). Septal contrast enhancement was particularly associated with bowing of the interventricular septum. Finally, in Chapter 5, dobutamine stress-CMR was used to determine the individual reasons for right and left ventricular stroke volume impairment during exercise in PH patients. ∆ RV stroke volume appeared limited by diminished contractile reserve as ∆ RVEF was lower in PH patients (27%) compared to controls (38%) and ∆ RVEF correlated with ∆ RV stroke volume (r = 0.94, p < 0.001). ∆ LV stroke volume appeared limited by impaired filling, probably due to reduced LV preload as RV stroke volume and LV end-diastolic volume remained closely related at rest (r = 0.821, p < 0.001) and stress (r = 0.693, p = 0.003)

Quantitative Three-dimensional Echocardiography

Echocardiography is the most important non-invasive diagnostic tool for the clinical management of cardiac patients1. Measurement of left ventricular volume and function are the most common clinical referral questions to the echocardiography laboratory because of its value in clinical decision-making, assessment of therapeutic effects and determination of prognosis. Therefore, an accurate, fast and easy measurement of left ventricular volume and function is important. Two-dimensional echocardiography remains the most widely used method, but the advantages of three-dimensional echocardiography over two-dimensional echocardiography are increasingl