Hi there,
Specific kennel cough is caused by an infection - usually by an organism called bordetella, and does not generally cause long term heart disease as it is an infection of the upper respiratiry tract rather then the heart or lungs. Heart conditions are due to the dysfunction of the heart because of the shape of the valces or problems with the heart muscle or electrical cimmunications within the heart - very occasionally, infections can cause damage to the heart valves - but I really would not expect this of kennel cough.
Often, dogs with mild heart disease and heart murmurs do not show any signs in their day-to-day life and so there is no real sign that a problem is present. A cough can be a sign of heart disease starting to deteriorate, and sometimes this cough can sound like kennel cough, although they can generally be told apart on exam and by listening with a stethoscope. Alternatively, if you have take your dog to the vet with kennel cough, they may have picked up a previously non-diagnosed heart problem whilst listening to the chest.
I hope this helps,
Let me know if you have any more questions,
Jen
