Echocardiographic Assessment of Atrial Function: From Basic Mechanics to Specific Cardiac Diseases

Figures

• 

  Figure 1. Left atrial pressure–volume loop curve. (A) Normal left atrial pressure–volume loop consisting of A- and V-loops. The A-loop is produced by LA contraction (booster pump function) and relaxation (early reservoir function), while the V-loop is produced by LA dilatation (late reservoir function) and emptying (conduit function). LA pressure includes the x-trough and v-wave pressures, and the slope connecting the two pressure points (dotted line) on the loop is defined as the LA stiffness index. (B) During afterload increase. When systolic blood pressure increases from 120 to 180 mmHg for instance, left ventricular (LV) systolic and diastolic function worsen due to afterload increase. The A-loop area immediately enlarges to pressure-overloaded LV dysfunction, resulting in the maintenance of stroke volume without a critical elevation in LA pressure. (C) Atrial fibrillation occurrence. Atrial fibrillation promotes atrial myopathy, resulting in LA dilatation, functional impairment and perhaps elevated mean LA pressure. The A-loop disappears during atrial fibrillation, and it mainly depends on ventricular function to maintain cardiac performance. (D) Left atrial stiffening. The…

• 

  Figure 2. Calculation of left atrial strain. LA strain can be analyzed from a non-foreshortened apical four-chamber view. The zero-strain reference is set at end-diastole according to the recommendation by Badano et al. [17], enabling one to obtain LA strain value even in patients with atrial fibrillation. LA reservoir strain (LASr) is calculated as difference between end-diastole and onset of early LV filling, while LA pump strain (LASp) as difference between onset of atrial contraction and onset of late LV filling. LA, left atrial, LV, left ventricular.

• 

  Figure 3. Calculation of left atrial dispersion. LA dispersion is defined as the standard deviation of the time to peak positive strain corrected by the R-R interval (%). White arrows indicate contraction durations defined as the time from the R wave on the electrocardiogram to the maximal time of positive deformation in each LA segment. LA, left atrial.

• 

  Figure 4. Visual assessment (grading) of left atrial reservoir function. (A) A case of hypertrophic cardiomyopathy. (B,C) Two cases of cardiac amyloidosis. The upper panel in each case is a frame when the LA size is minimized, while the lower panel is a frame when the LA size is maximized. In a patient with hypertrophic cardiomyopathy, the LA dilatation grade (Inoue grade) was preserved (A). In contrast, two patients with cardiac amyloidosis showed abnormal (B) and restricted (C) LA dilatation, indicating LA stiffening. LA, left atrial.

• 

  Figure 5. Atrial function in atrial septal defect and Fontan palliation. (A) TEE showing a right-to-left (R-L) shunt from a residual leak after ASD device closure with RA dysfunction. (B) Four-chamber views of end-systole (RAA max) and end-diastole (RAA min). The decreased RA fractional area change (FAC) suggests RA dysfunction. (C) Illustration of the Fontan circulation and the process of impairment of systemic ventricular relaxation after Fontan palliation. (D) Transmitral Doppler early diastolic (E-wave) and late diastolic (A-wave) velocities in a control subject, and the SV peak E-wave and A-wave inflow velocities in a patient with Fontan palliation (EC-TCPC). (E) Representative atrial strain curves in a patient with Fontan palliation (EC-TCPC) and a control subject. Peak negative (red arrow) and positive (white arrow) atrial strain are noted. TEE, transesophageal echocardiography; ASD, atrial septal defect; RA, right atrial; RAA, right atrial area; EC-TCPC, extracardiac total cavopulmonary connection.