German to English Medical Medical: Cardiology

Chest X-ray.
It reveals no abnormal findings ( no blunting of costophrenic angles, no signs of pulmonary congestion); nevertheless the last sntence reads:

"Der Herzschatten ist mangelhaft gegliedert und grenzwertig groß."

I have "obscured cardiac silhouette" or cardiac silhouette without sharp contours", but I am not sure whether that's really the exact meaning.

Help anyone?

Thanks!