Some babies who have heart problems are very sleepy and don't automatically cry when they are hungry, so you may have to wake them for feeds. You can try changing them, rubbing or tickling their feet or perhaps bathing them, different things work for different babies. You may also need to keep them awake by stimulating them during the feed.
Babies will often fall asleep part way through feeding without taking a full feed which may then mean that their next feed is needed earlier and this combined with the length of time needed for each feed can mean that parents seem to spend virtually all their time feeding.
A little and often approach is much better than trying to force them to take a whole feed that they just can’t manage.
Don't feel bad by accepting any offers you get to help with the housework and washing, as much of your time will be taken up with feeding in the first few months.
Even if you don't have the network of family and friends to help, don't be worrying about the dust and dishes!! You'll soon catch up with the housework when life settles down.