Bronchiectasis is the dilatation of bronchi or their branches, causing a risk of infection and continual coughing.
The second syllable is the primary accented syllable Bronchi 'ectasis. given to the fact that the word is formed by the greek bronkhia (denoting the branches of the main bronchi) + ektasis and given to the fact that what causes the problem is the "ektasis" of the "bronkhia", the stressed in intonation goes to it.