In patients with end-stage HF, left atrial pressure exceeds right atrial pressure, and echocardiographic identification of left to right shunting is performed with colored Doppler after adjusting velocity range to 30–40 cm/s using bicaval view (midesophageal, rotation 90°, ◘ Fig. 17.2). Contrast echocardiography is obsolete in this indication. Because of the profound hemodynamic changes following LVAD implantation with right atrial pressure now exceeding left atrial pressure, determination of shunting volume at this time does not support decision making. Postoperative risks in patients with PFO include right to left shunting with consequent decrease of arterial oxygen saturation and, in the long term, systemic embolization via PFO. In VAD surgery, direct closure (in case of bicaval cannulation) or interventional closure with an occluder (in case of VAD implantation via minimal approach without CPB) has to be considered.

In the case of aortic regurgitation (AR) following LVAD implantation, efficiency of mechanical support decreases, LV unloading is inadequate, and patients clinically present with limited exercise tolerance due to increased pulmonary pressures and subsequent right ventricular failure.

Careful quantification of AR is important. Due to increased left ventricular diastolic pressure in patients with end-stage HF, assessment by color Doppler may underestimate the degree of regurgitation. Therefore, quantification of AR has to be repeated while on cardiopulmonary bypass when hemodynamics are similar to the situation after LVAD implantation. Thus, it is possible to estimate the degree of AR following LVAD implantation.

Using the long axis aortic view (midesophageal, 120°) in color Doppler modus, the width of the regurgitant jet (1 cm below its origin) relative to the width of the left ventricular outflow tract is calculated, and a value above 25% identifies moderate to severe regurgitation (◘ Fig. 17.3).

It is generally accepted that AR of moderate or higher degree presents an indication for concomitant aortic valve surgery [2].

Following LVAD implantation, the right ventricle (RV) receives systemic venous blood and generates transpulmonary flow and adequate loading of the left ventricle and consequently of the LVAD. Right ventricular failure (RVF) is a well-known and frequent complication during the early post-procedural period. In high-volume centers, incidence of RVF decreases below 10%, probably due to exact pre- procedural risk stratification and therapy adjustment [3, 4].

TEE provides valuable information about RV morphology and function. To assess RV inflow tract and apex, acquisition of the midesophageal 4-chamber view (ME 4C) is necessary. Turning the probe to the right until the tricuspid valve comes into the center of the display and adjustment of probe depth to visualize the RV apex help to optimize image acquisition. To quantify RV geometry, annular (RVEDD 1), midcavity (RVEDD 2), and maximal (RVEDD max) short axis diameters at end-diastole are measured (◘ Fig. 17.4a). For assessment of RV function, the RV fractional area change using end-diastolic and end-systolic areas measured in the ME 4C view is calculated. Additional assessment of the RV systolic function includes measurement of tricuspid annular systolic plane excursion (TAPSE) from the ME 4C view using anatomical M-mode (◘ Fig. 17.4b). In patients scheduled for VAD implantations, critical values for these echocardiographic parameters are RVEDD >40 mm, RV FAC <20%, and TAPSE <10 mm [5].