Response by Asrress et al to Letter Regarding Article, "Physiology of Angina and Its Alleviation With Nitroglycerin: Insights From Invasive Catheter Laboratory Measurements During Exercise". Issue 7 (13th February 2018) - Asrress, Kaleab N.; Williams, Rupert; Lockie, Timothy; Khawaja, Muhammed Z.; Patterson, Tiffany; Arri, Satpal; De Silva, Kalpa; Perera, Divaka; Marber, Michael S.; Redwood, Simon R.