As this, and most deer vital diagrams clearly show, a heart shot is also a double lung shot, since the heart sits low in the chest, in between the lungs. You cannot hit the heart and not hit the lungs at most angles. Im also not sure why aiming at the center of the lungs would prevent a shoulder shot, if the hit was slightly forward, since your aiming right behind the shoulder, regardless of whether you aim for the center of the lungs, or lower for the heart.

Its really a no brainer, aim slightly low in the heart area, and you will hit the LUNGS AND HEART, if the deer does not duck down. if the deer does duck down, you still hit center of the lungs.