Improved methods and apparatuses for heart valve repair in a beating heart of a patient utilize an exchangeable heart valve repair system. Heart valve repair system can include a port adapted to be seated in the heart wall and a catheter slidable within the port. The catheter can be selectively locked relative to the port for insertion into the heart and unlocked once the port is seated to allow the catheter to move distally towards target tissue. System elements can be selectively removed from and replaced within port to deploy repair devices while port maintains a seal while elements are and are not inserted.