An epicardially placed accelerometer can assess changes in preload in real-time

A miniaturized accelerometer can be incorporated in temporary pacemaker leads which are routinely attached to the epicardium during cardiac surgery and provide continuous monitoring of cardiac motion during and following surgery. We tested if such a sensor could be used to assess volume status, which is essential in hemodynamically unstable patients. This novel method can facilitate continuous monitoring of the volemic status in open-heart surgery patients and help guiding fluid resuscitation.

Temporary pace leads are routinely placed on the heart during open heart surgery. Miniaturized accelerometers can be combined with temporary pace leads providing a possibility to extract more valuable clinical information of hemodynamic status of the patient without any added surgical procedure. Such information can include heart wall motion and thus ventricular function. We have previously demonstrated this concept of monitoring cardiac function in real time, including automatic detection of myocardial ischemia and evaluation of inotropic state.

In cardiac surgery, assessments of intravascular volume state and preload are essential as volume expansion usually is the first line of therapy in a bleeding patient postoperatively. An accelerometer, incorporated in the temporary pace leads, may potentially also be used for such assessment and for guiding fluid therapy during hemodynamic instability. Such a device could entail a temporary pace wire with accelerometer incorporated connected to a bedside monitor that continuously estimates the left ventricular volume.