It is possible to have an enlarged heart due to hiatal hernia. It seems the etiology would be to reduce lung capacity, and that may contribute to asthema and heart disorder. The reduced respiration ability can cause the heart to beat faster, and the additional stress on the heart can cause an enlargement of the left ventrical to compensate. Also, there can be a crowding out effect where the hernia can push against the bottom of the heart that would also stress the anatomy of the heart.
Thanks for sharing, and take care.