A simulation study of left ventricular decompression using a double lumen arterial cannula prototype during a veno-arterial extracorporeal membrane oxygenation

Abstract

Background: Veno-arterial extracorporeal membrane oxygenation can be vital to support patients in severe or rapidly progressing cardiogenic shock. In cases of left ventricular distension, left ventricular decompression during veno-arterial extracorporeal membrane oxygenation may be a crucial factor influencing the patient outcome. Application of a double lumen arterial cannula for a left ventricular unloading is an alternative, straightforward method for left ventricular decompression during extracorporeal membrane oxygenation in a veno-arterial configuration.

Objectives: The purpose of this article is to use a mathematical model of the human adult cardiovascular system to analyze the left ventricular function of a patient in cardiogenic shock supported by veno-arterial extracorporeal membrane oxygenation with and without the application of left ventricular unloading using a novel double lumen arterial cannula.

Methods: A lumped model of cardiovascular system hydraulics has been coupled with models of non-pulsatile veno-arterial extracorporeal membrane oxygenation, a standard venous cannula, and a drainage lumen of a double lumen arterial cannula. Cardiogenic shock has been induced by decreasing left ventricular contractility to 10% of baseline normal value.

Results: The simulation results indicate that applying double lumen arterial cannula during veno-arterial extracorporeal membrane oxygenation is associated with reduction of left ventricular end-systolic volume, end-diastolic volume, end-systolic pressure, and end-diastolic pressure.

Conclusions: A double lumen arterial cannula is a viable alternative less invasive method for left ventricular decompression during veno-arterial extracorporeal membrane oxygenation. However, to allow for satisfactory extracorporeal membrane oxygenation flow, the cannula design has to be revisited.

Keywords: Extracorporeal membrane oxygenation; cannula; circulation; double lumen cannula; model; modelica.

Figure 1:

Schematics showing LV unloading using the DLAC during VA ECMO and a detail of the DLAC prototype

Figure 2:

Pressure drop as a function of flow for a standard venous cannula (blue) and a left ventricle drain through the 10 Fr drainage lumen of a DLAC (red, striped), rescaled to the length required to reach into the ventricle. The fit is based on data measured on water reported by the manufacturer. Infusion lumen of the DLAC has been fitted to data measured with blood (green) and compared to the data provided by the manufacturer (green, striped).

Figure 3.

The model of a cardiovascular system (A), the model of a cardiovascular system with VA ECMO and standard cannulas (B), and the model of a cardiovascular system with VA ECMO and a DLAC application (C), where the drainage lumens are modeled as an exponential resistances.

Figure 4.

A) Simulation results of LV PV loops of a patient with cardiogenic shock under VA ECMO. ECMO flow is from 0.1 to 7 l/min. The aortic valve remain closed, even during systole, when ECMO flow reaches 6 l/min and 7 l/min. B) Simulation results of LV PV loop of a patient with cardiogenic shock under the ECMO with DLAC application. ECMO flow is from 0.1 l/min to 7 l/min. The aortic valve remain closed, even during systole, when ECMO flow reaches 5 l/min, 6 and 7 l/min and the LV is sufficiently unloaded by DLAC.

Figure 5.

Simulation results of PV loop of a healthy person (green), a patient with cardiogenic shock (red), a patient with the cardiogenic shock during VA ECMO therapy (black), and a patient with the cardiogenic shock under the ECMO with DLAC application (blue). The ECMO flow was set to 3 l/min for all cases.

Figure 6.

Simulation results of LV volume during the cardiac cycle. A patient with cardiogenic shock without ECMO application (magenta); a patient with cardiogenic shock with 5 l/min ECMO (blue); a patient with cardiogenic shock with 5 l/min ECMO with DLAC application (red), a - aortic valve opens, b - aortic valve closes, c - mitral valve opens, d - mitral valve closes. Note, that the aortic valve might not open at all in some cases.