Minimally invasive mitral valve (MV) surgery has presumed advantages over that performed through median sternotomy. Smaller incisions are associated with reduced pain, reduced blood loss and transfusions, faster recovery, shorter hospital length of stay, and increased patient satisfaction. However, this approach is also associated with longer cardiopulmonary bypass (CPB) and cross-clamp times and complications unique to femoral cannulation and femoro-femoral bypass.1
Cardiac herniation is an extremely rare complication initially reported by Bettman and Tannenbaum in 1948.2 It usually follows blunt chest trauma3 or pneumonectomy,4 but can potentially occur after any minimally invasive surgery involving a pericardial incision. In this case report, we present 2 cases of cardiac herniation occurring after minimally invasive MV surgery; the 2 cases had different surgical exposures and clinical presentations. Early diagnosis is crucial for a timely lifesaving definitive management.
Waiver of patient consent was obtained from IRB because both patients could not be reached.
CASE DESCRIPTION 1
A 44-year-old man with asymptomatic severe degenerative MV disease and severe mitral regurgitation underwent mitral valvuloplasty through a 4-cm right minithoracotomy. After induction of general anesthesia, a double-lumen tube was placed to facilitate left-sided 1-lung ventilation. The right internal jugular vein was percutaneously cannulated by both 7.5-Fr triple-lumen, and 16-gauge single-lumen catheters. Femoro-femoral CPB was started after femoral arterial and venous cannulation. The pericardium was opened, and a coronary sinus catheter was placed by the surgeon. MV prolapse was repaired, and a Duran ring was placed. Successful repair was confirmed by easily acquired standard transesophageal echocardiography (TEE) views (Fig. 1A; Video 1, see Supplemental Digital Content 1, http://links.lww.com/AACR/A2.
While being moved from the operating room table to the intensive care unit (ICU) bed at the end of surgery, the patient became hypotensive but responded to fluids and intermittent boluses of vasopressors. A TEE probe was replaced for further evaluation of the etiology of hypotension, but we were unable to adequately image the heart with standard midesophageal views (Fig. 1B; Video 2, see Supplemental Digital Content 2, http://links.lww.com/AACR/A3), and completely unable to visualize the heart with transgastric views. The descending aorta was visualized, and no dissection was noted. The chest was reexplored because of continued need for vasopressor support and inability to image the heart adequately. On surgical exposure, the right lung was found to be incompletely inflated and the heart had herniated through the pericardial defect and was twisted over its primary axis into the right hemithorax. After simple manual repositioning of the heart, stable hemodynamics and standard TEE views were restored (Fig. 1C; Video 3, see Supplemental Digital Content 3, http://links.lww.com/AACR/A4); findings were unchanged from the TEE examination done immediately after MV repair. The pericardium was closed with 3 interrupted sutures, and the right lung was reinflated under direct visualization. The patient was transported to the ICU in stable condition; he was later transferred to the floor on the first postoperative day (POD) and was discharged on the fourth POD after an uneventful hospital course.
CASE DESCRIPTION 2
A 49-year-old man with asymptomatic severe degenerative MV disease and severe mitral regurgitation underwent robotically assisted minimally invasive mitral valvuloplasty through multiple small ports in the right chest. Anesthetic and surgical management was similar to that of the first case with the exception that a coronary sinus catheter was not placed, and only antegrade cardioplegia was delivered. MV repair was successful as confirmed by TEE examination done after CPB; the patient was transported to the ICU after an uneventful intraoperative course.
Routine chest radiograph performed on ICU admission revealed herniation of the heart into the right hemithorax (Fig. 2A). The patient was completely asymptomatic, chest radiograph was repeated after leaning the patient toward his left side, but it was unchanged. The patient was transferred back to the operating room, the heart was manually repositioned to its anatomical position, and the pericardial defect was closed with a synthetic patch. A chest radiograph on arrival to the ICU confirmed that cardiac herniation was corrected (Fig. 2B). The patient was transferred to the floor on the first POD and was discharged on the sixth POD after an uneventful hospital course.
Cardiac herniation is a very rare and dangerous complication with a mortality rate approaching 50%.5 The few recent reports of cardiac herniation after minimally invasive cardiac surgery6–8 all had different clinical presentations. Symptoms depend on the side of cardiac herniation; only right-sided herniation is possible with minimally invasive MV surgery as the pericardium is incised on the right side. Right-sided herniation has a wide spectrum of presentations from asymptomatic to severe hypotension, tachycardia, and superior vena cava syndrome; the presentation usually depends on the degree of impediment of superior and inferior vena caval inflow.9 One of our patients was completely asymptomatic, while the other exhibited mild hemodynamic instability that was controlled with fluids and vasopressors. Nonspecific symptoms make the diagnosis of cardiac herniation more difficult. However, timely diagnosis is critical because if the patient’s condition deteriorates and cardiopulmonary resuscitation is initiated, chest compressions are useless because the heart is not in its anatomical position.
Factors triggering cardiac herniation include a marked increase in intrathoracic pressure, which is usually associated with excessive ventilation of the contralateral lung (e.g., strong positive pressure ventilation when coming off CPB), coughing on extubation, excessive suction from ipsilateral chest tubes, or positioning the side of surgery more dependently.10 In our first case, turning the patient to his right side to place the roller underneath him or the acceleration–deceleration associated with patient movement to the ICU bed likely facilitated herniation of the heart through the open pericardium into the right chest cavity. However, in our second case, the event triggering the herniation is uncertain given that it was asymptomatic and unrecognized until ICU admission. It is important to avoid triggering factors within the first 24 hours after surgery; the vast majority of cardiac herniations have been reported during that time frame. Adhesions tend to form between the pericardium and the heart very quickly, decreasing the incidence of late cardiac herniation.11
Diagnosis of cardiac herniation may be confirmed by chest radiograph revealing a “snow cone” shape of the right border of the heart if herniation is partial or impending,12 or as in our second case, it may reveal a complete herniation with shifting of the cardiac shadow from the left to the right hemithorax. Chest radiograph can also reveal reversal of a pulmonary artery catheter loop and rotation in a clockwise fashion.13 Computed tomography scan,7 magnetic resonance imaging,3 transthoracic echocardiography,11 TEE, and video-assisted thoracoscopy8 have been used in different capacities to diagnose cardiac herniation as well. While hypotension after cardiac surgery is not uncommon, and in our first case initially responded to fluids and vasopressors, it was the inability to image the heart adequately from standard TEE views that alerted our team to the possibility of cardiac herniation, particularly recognizing that standard views were easily acquired a few minutes earlier.
Definitive management of cardiac herniation includes surgical exploration to reposition the heart back to its anatomical position and closing the pericardial defect primarily or using synthetic mesh or bovine pericardium. Additional treatment measures include positioning the nonsurgical side more dependently and avoiding hyperinflation of the contralateral lung.9 It is prudent to routinely close any pericardial defect after minimally invasive cardiac surgery irrespective of how small it is. However, cardiac herniation should always be considered even if the pericardium was repaired; herniation has been reported to happen when the pericardial repair broke in the early postoperative period.14
In this case report, we present 2 patients in whom right-sided cardiac herniation followed minimally invasive mitral valvuloplasty. The 2 examples of herniation had different clinical presentations, which made the diagnosis more difficult. Cardiac herniation is an extremely rare and potentially fatal complication requiring early detection and timely definitive management.
1. Modi P, Hassan A, Chitwood WR Jr. Minimally invasive mitral valve surgery: a systematic review and meta-analysis. Eur J Cardiothorac Surg. 2008;34:943–52
2. Bettman RB, Tannenbaum WJ. Herniation of the heart: through a pericardial incision. Ann Surg. 1948;128:1012–4
3. Sohn JH, Song JW, Seo JB, Do KH, Lee JS, Kim DK, Song KS, Lim TH. Case report: pericardial rupture and cardiac herniation after blunt trauma: a case diagnosed using cardiac MRI. Br J Radiol. 2005;78:447–9
4. Mehanna MJ, Israel GM, Katigbak M, Rubinowitz AN. Cardiac herniation after right pneumonectomy: case report and review of the literature. J Thorac Imaging. 2007;22:280–2
5. Self RJ, Vaughan RS. Acute cardiac herniation after radical pleuropneumonectomy. Anaesthesia. 1999;54:564–6
6. Wasir H, Malhotra R, Vats M, Sharma KK, Mehta Y, Trehan N. Cardiac herniation following atrial septal defect closure using port access surgery. Indian Heart J. 2006;58:260–2
7. Speggiorin S, Padalino MA, Vida VL, Bonato R, Stellin G. Cardiac herniation after minimally invasive cardiac surgery: an unusual potentially lethal complication. Circulation. 2009;120:2509–10
8. Yamaguchi S, Ishikawa N, Watanabe G. Cardiac herniation during robot-assisted cardiac operation. J Thorac Cardiovasc Surg. 2012;143:e10–1
9. Cassorla L, Katz JA. Management of cardiac herniation after intrapericardial pneumonectomy. Anesthesiology. 1984;60:362–4
10. Shimizu J, Ishida Y, Hirano Y, Tatsuzawa Y, Kawaura Y, Nozawa A, Yamada K, Oda M. Cardiac herniation following intrapericardial pneumonectomy with partial pericardiectomy for advanced lung cancer. Ann Thorac Cardiovasc Surg. 2003;9:68–72
11. Nanda S, Pamula J, Bhatt SP, Turki MA, Myers E, Dale T. Cardiac herniation and volvulus with acquired dextrocardia: echocardiographic diagnosis. Echocardiography. 2007;24:870–4
12. Gurney JW, Arnold S, Goodman LR. Impending cardiac herniation: the snow cone sign. Radiology. 1986;161:653–5
13. Brogdon BG, Georgy BA. An unusual twist. Br J Radiol. 1998;71:691–2
14. Veronesi G, Spaggiari L, Solli PG, Pastorino U. Cardiac dislocation after extended pneumonectomy with pericardioplasty. Eur J Cardiothorac Surg. 2001;19:89–91