It categorizes the dissection based on where the original intimal tear is located and the extent of the dissection (localized to either the ascending aorta or descending aorta or involving both the ascending and descending aorta). Type I – originates in ascending aorta, and propagates at least to the aortic arch and often beyond it distally. It is most often seen in patients less than 65 years of age and is the most lethal form of the disease. Type II – originates in the ascending aorta and is confined to it. Type III – originates in the descending aorta and rarely extends proximally, but will extend distally. It most often occurs in elderly patients with atherosclerosis and hypertension. Stanford
The Stanford classification is divided into two groups, A and B, depending on whether the ascending aorta is involved. A – involves the ascending aorta and/or aortic arch, and possibly the descending aorta. The tear can originate in the ascending aorta, the aortic arch, or more rarely, in the descending aorta. It includes DeBakey types I and II. B – involves the descending aorta or the arch (distal to the left subclavian artery), without the involvement of the ascending aorta.
In 1915, during the Armenian genocide, Turks and Kurds, led by Jevdet Bey Pasha, massacred some 15,000 Armenians in Bitlis.In February 1916, as part of the Caucasus Campaign, Imperial Russian forces launched an offensive to capture Mush and Bitlis. Mush fell on February 16. At Bitlis, the Turkish positions were in a strong location on the outskirts of the town and could not be outflanked because of the narrowness of the valley. On the night of March 2–3, during a blizzard, the Russian 8th Caucasian Rifles advanced silently and, after several hours of hand-to-hand fighting, took the Turkish positions with 1,000 prisoners. The Turks then abandoned Bitlis, retreating towards Siirt. The Russian forces and intelligence officers found evidence of the massacres of Christians by the Kurdish and Turkish radicals in 1915. In August 1916 the Turkish Second Army started an offensive against the Russian front in eastern Turkey. On August 2, the Ottoman 16th Corps, together with strong Kurdish irregulars support, attacked Bitlis and Mush. Fearing encirclement General Nazarbekov, the Russian commander, abandoned Bitlis on August 5. When Mush also fell, he decided to abandon Tatvan and the whole Mush valley and retreat to Ahlat. Around 18 August, the Russians having been reinforced, were able to counter-attack. By September the Turkish offensive was stalled and then turned. Nazarbekov advanced as the Turkish forces withdrew from Tatvan and Mush, but he did not have the available forces to hold Bitlis as winter approached. The Russian February Revolution in the spring of 1917 prevented any further Russian gains.