Effective Diastolic Mechanical Support Using a New Implantable Cardiac Compression Device

Abstract

<h3>Purpose</h3> Diastolic mechanical cardiac assist has been difficult to provide. We examined the hemodynamic effects of a new, implantable cardiac assist system on ovine cardiac performance. The device is inserted via the apex of the pericardium. It encompasses and encircles both left and right ventricles. The device self-expands to encompass the heart without suturing; it is held in place by the pericardium. There are 2 concentric chambers. An internal chamber is saline-filled and conforms to the heart. An external chamber is air-filled and provides external compression followed by negative pressure to aid with relaxation. (See figure). Device compression and relaxation is EKG-triggered. <h3>Methods</h3> The device was implanted in 7 sheep with heart failure induced by microsphere embolization. Cardiac performance was assessed for 6-8 hours. Invasive monitoring with a Swan-Ganz catheter, LV catheter, and flow probes provided data on cardiac function. <h3>Results</h3> Initiation of cardiac assist resulted in increased cardiac output of up to 0.7 L/min (21% increase). Systolic BP increased by 15 mmHg (22% increase). Mean pulmonary artery pressure decreased by 3 mmHg (10% decrease). Filling pressures declined indicating ventricular and pulmonary artery unloading. Diastolic pulmonary pressure declined by 7mmHg on average (from 23mmHg to 16 mmHg; -30%). LVEDP declined from 17 mmHg to 13 mmHg. Increased -dP/dt was dramatic after device activation (see figure) <h3>Conclusion</h3> Diastolic, and systolic, cardiac assistance can be achieved with a new implantable device that encompasses the heart compressing and relaxing sequentially in an ovine model of heart failure.