Here, we highlight two important clinical findings. First, cardiac herniation was visualized using TEE images showing the pronounced movement of the left ventricular apex during the cardiac cycle in the right mini-thoracotomy MICS, which included robotic-assisted mitral valve surgery. Second, the cardiac herniation was effectively repaired by deflating the left lung and hyperinflating the right lung separately using a double-lumen tube without re-thoracotomy.
However, only a few previous studies have reported the rare complications of cardiac herniation after right mini-thoracotomy MICS [3,4,5]. In this technique, the right side of the pericardium is always incised for cardiac exposure. In our TERMVR procedures, the pericardium is not sutured closed because the autologous pericardium is harvested intraoperatively for suture reinforcement and hemostasis in all cases, and in a few cases, for mitral valve augmentation. At our institute, 796 cases of robotic-assisted mitral valve repairs were performed between May 2014 and May 2022. We did not experience any complications after keeping the right pericardial open [7]. This procedure is standard practice in our institute and was the first case where cardiac herniation occurred through a right pericardial opening at our institute.
The cause of cardiac herniation in our case was unknown. Since we failed to directly observe cardiac herniation through endoscopy, perhaps cardiac herniation occurred because of the left lung over-expansion before the two-lung ventilation was restarted. However, we always used PCV settings during OLV. Here, maximal airway pressure did not exceed 15 cmH2O during OLV, and we presume that this airway pressure did not induce overinflation of the left lung.
Previous reports on cardiac herniation in MICS include only one case of hemodynamic deterioration [3,4,5]. Here, ventricular extrasystoles and hypotension were also recognized. The hypotension after weaning from CPB may have been caused by hemorrhage, cardiac tamponade, or sudden cardiac dysfunction. TEE is a useful tool for diagnosing hemodynamic deterioration during cardiac surgery. However, the typical TEE findings of cardiac herniation are unknown. The pathophysiology of cardiac herniation is a deviation of the left ventricular apex toward the right thoracic cavity.
It has been reported that TEE cannot acquire standard mid-esophageal views and cannot visualize the heart through a transgastric view [5]. Here, the TEE findings on a four-chamber mid-esophageal view showed pronounced left ventricular apex movement, which is stationary in normal conditions, during the cardiac cycle (Fig. 1). The TEE findings on a transgastric short-axis view also showed a swing of the left ventricle caused by left ventricular apical deviation, as observed in acute cardiac tamponade. Furthermore, the TEE images captured in our case are the first to be reported, which could contribute to future diagnosis of cardiac herniation in cases showing pronounced left ventricular apical motion and left ventricular swing.
It has been reported that in patients with trauma, emergency open surgery to repair the cardiac deviation and close the pericardium is the treatment for cardiac herniation [1]. In cardiac herniation after pneumonectomy, the resected pericardium is repaired with an expanded polytetrafluoroethylene sheet [2]. Here, cardiac herniation repair was initiated using a double-lumen tube, routinely used in MICS, to deflate and hyperinflate the left and right lungs, respectively. MICS is frequently performed using a double-lumen endobronchial tube for general anesthesia to facilitate lung isolation. We speculate that although the pericardium is exposed in MICS, no space is created as in pneumonectomy; therefore, cardiac herniation does not recur despite an open pericardium. Therefore, cardiac herniation after mini-thoracotomy MICS can be effectively repaired without re-thoracotomy.
This was a very unusual case of cardiac herniation during TERMVR, visualized using TEE images. Moreover, the cardiac herniation was successfully repaired using a double-lumen tube without re-thoracotomy.