Critical anatomic dimensions for intrathoracic circulatory assist devices

The design of totally implantable circulatory support devices must account for the anatomical constraints of the body cavity. To aid development of an implantable electrohydraulic ventricular assist device (EVAD), thoracic anatomical measurements and fit trials were performed. Various dimensions of the thoracic cavity were measured in 19 preserved and fresh cadavers. The mean left ventricle apex to chest wall distance was 2.7 +/- 0.2 cm. The mean sagittal radius of curvature at the fifth rib was 11.1 +/- 0.4 cm, and the transverse radius at the fifth rib was 9.4 +/- 0.3 cm. The mean sternal length was 18.9 +/- 1.2 cm. Using these measurements a model measuring 17.5 x 10.5 x 3.8 cm was designed. This model was placed in the chest of 11 patients undergoing open heart surgery. In one patient there was significant lung compression and in another hypotension suggesting great vessel compression. Finally, 1 of 11 patients had a short sternum and a small thorax, and the device did not fit. In conclusion, thoracic measurements may be used in the design of circulatory support devices. The model fit adequately in 73% of patient trials.