Support for Postinfarction Ventricular Septal Rupture: Keep it Simple, Swift, and Safe.

Abstract

To the Editor: I read with much interest the case series by Ruiz Duque et al.1 on four patients with surgical repair of postinfarction ventricular septal rupture (PIVSR) treated with Impella. The authors propose to use Impella in patients with Qp/Qs >2.5. They also raise possible concerns related to the strategy. Several issues repetitively emerge when discussing the use of Impella in PIVSR patients. First, PIVSR patients differ to much degree. We recently treated a 61 year old male patient with 16 mm inferobasal PIVSR, invasively measured Qp/Qs of 3.3, occluded distal right coronary artery and small segmental akinesia of inferior left ventricular wall. To much of our surprise, complete hemodynamic stabilization was achieved with intra-aortic balloon pump only. There was no need for mechanical ventilation, shock resolved within 1 h, lactate levels normalized, renal function recovered completely and minimal analgesia with no sedation was needed. Patient underwent successful surgical repair after 10 days of support with no need for postoperative mechanical circulatory support (MCS). Such shunt usually advocates MCS upgrade, however, in this case it was not required. It would be interesting to hear the authors explanation for the proposed Qp/Qs threshold. I wonder what other patient features would promote (or demote) upgrade in MCS treatment? Systolic function of both ventricles, stage of the shock, severity of multiorgan failure, further extension of PIVSR, are among potential candidates. Second, two issues frequently emerge when considering Impella usage for PIVSR. One is the possibility of necrotic debris systemic embolization. Given the current data, Impella is optimal MCS for reducing shunt fraction.2 By such action sheer forces delivered at the necrotic edges of PIVSR are minimized, thus lowering the risk of embolization. On the other hand, MCS or no MCS, the risk of embolization is still present. Implementing MCS strategies that increase shunting, such as veno-arterial extracorporeal membrane oxygenation, could even provoke such embolic events, although we can argue that due to higher left-to-right shunting these events would be pulmonic, not systemic. Direct severing of the debris by the impeller is highly unlikely. Nevertheless, the outcome would be either pump obstruction or debris fragmentation, resulting in reduced intensity of embolic event. The other issue is the possibility of producing right-to-left shunting.3 However, this should occur only in case of high Impella flow levels.4 Despite Impella, left ventricular pressure created by the systole should prevent or even reverse the shunt throughout a significant fraction of cardiac cycle. Indeed, Sato et al.5 reported conversion of the shunt to right-to-left direction only at flow level P6 and systemic deoxygenation at P8. By adjusting the flow under echocardiogram, the authors successfully prevented further deoxygenation. So, despite the likelihood of systemic deoxygenation, meticulous guiding of the level of the support should prevent this issue. The optimal MCS strategy for such hemodynamically fragile patients as PIVSR patients should be simple, swift, and safe. Impella is swift and simple. There is no extensive evidence it is not safe. It should be our first choice in PIVSR.