Carcinoid syndrome symptoms include Flushing Diarrhea Bronchospasm Chronic sequelae of carcinoid syndrome include Telangiectasias Right-sided valvular heart disease Retroperitoneal fibrosis A left-sided heart murmur (mitral stenosis or regurgitation) due to serotonin - induced valvular damage occurs rarely with bronchial carcinoids (as opposed to the right-sided valvular lesions of gastrointestinal carcinoids).