Relationship of left atrial appendage function to left ventricular function

BACKGROUND: The study was conducted to evaluate the relationship of left atrial appendage function to left ventricular function and to analyze, if left ventricular dysfunction predisposed to left atrial appendage thrombus formation even in the presence of sinus rhythm. METHODS AND RESULTS: The study was conducted in 78 patients with a mean age of 53+/-8.5 years, all of whom were in sinus rhythm. Transesophageal echocardiography was performed to record the left atrial appendage emptying and filling velocity and to look for the presence of spontaneous echo contrast and thrombus. Patients with severe left ventricular dysfunction (Group I--left ventricular ejection fraction < 35%) and patients with moderate left ventricular dysfunction (Group II--left ventricular ejection fraction 35-45%) had lower left atrial appendage emptying velocity (33.6+/-16 and 39.7+/-19.5 cm/s, respectively) and filling velocity (41+/-14.7 and 41+/-17 cm/s, respectively) when compared to patients with preserved systolic function (Group II--left ventricular ejection fraction >45%), who had emptying and filling velocity of 55+/-16 and 56+/-15 cm/s, respectively (p <0.05). Twelve out of 32 (38%) patients with severe left ventricular dysfunction (Group I) and 7 out of 25 (28%) patients with moderate left ventricular dysfunction (Group II) had presence of left atrial appendage thrombus as compared to none of the patients with preserved left ventricular ejection fraction (Group III) (p <0.001). CONCLUSIONS: Patients with left ventricular dysfunction also had left atrial appendage dysfunction as evidenced by lower emptying and filling velocities and had increased incidence of thrombus formation.     

Evaluation of left ventricular function using left ventricular twist and torsion parameters

The left ventricular (LV) twist/torsion, wringing motion of the heart is a key element for regulating LV systolic and diastolic mechanics. Until recently, the evaluation of LV twist was limited to the research arena because of the requirement of invasive techniques or low availability of tagged MRI. The recent development of two-dimensional speckle tracking echocardiography enables the noninvasive measurement of LV rotation in humans. This article constitutes a practical guide for the measurement and interpretation of LV twist parameters using two-dimensional speckle tracking echocardiography and discusses its clinical usefulness for the evaluation of LV function.     

Evaluation of left ventricular diastolic function

Doppler echocardiography can provide insight into the diastolic properties of the left ventricle. The hemodynamic origins of the diastolic mitral flow velocity profile are reviewed and Doppler information is compared to other measures of left ventricular diastolic function. Factors affecting the mitral diastolic flow velocity in both normal populations and pathologic conditions are discussed and the reported normal indexes of diastolic transmitral velocity are criticized.     

MRI of left ventricular function.

Cardiac magnetic resonance imaging (CMR) is widely recognized as the most accurate noninvasive imaging modality for the assessment of left ventricular (LV) function. By use of state-of-the-art magnetic resonance imaging (MRI) scanners, electrocardiography (ECG)-gated cine images depicting LV function with high contrast and excellent spatial and temporal resolution are readily acquired in breath-holds of 5 to 10 heartbeats. For patients in whom breath-holding and ECG gating are difficult, real-time cine imaging without ECG gating and breath-holding can be performed. LV function can be qualitatively assessed from cine images, or alternatively, parameters such as LV volumes, ejection fraction, and mass may be quantified via computer-based analysis software. In addition, techniques such as myocardial tagging and newer variants can be used to qualitatively or quantitatively assess regional intramyocardial strain, twist, and torsion. Many of the CMR methods have undergone clinical evaluation in the settings of high-dose dobutamine stress testing and determination of myocardial viability. These methods are also very accurate for prognosis in coronary heart disease patients and may be quite useful for the detection of contractile dyssynchrony. When used together with other CMR techniques such as first-pass perfusion imaging or late gadolinium enhancement, CMR of LV function provides a wealth of information in a single imaging study.