{"id":18505,"date":"2020-02-13T11:00:37","date_gmt":"2020-02-13T16:00:37","guid":{"rendered":"https:\/\/circulatingnow.nlm.nih.gov\/?p=18505"},"modified":"2024-10-21T10:58:51","modified_gmt":"2024-10-21T14:58:51","slug":"the-development-of-the-debakey-classification-of-aortic-dissection","status":"publish","type":"post","link":"https:\/\/circulatingnow.nlm.nih.gov\/2020\/02\/13\/the-development-of-the-debakey-classification-of-aortic-dissection\/","title":{"rendered":"The Development of the DeBakey Classification of Aortic Dissection"},"content":{"rendered":"

By Susan Green <\/em>~<\/p>\n

Aortic dissection<\/a> is a life-threatening catastrophic event. Essentially, the inner layer of the aorta splits and creates a false channel for blood flow. Without treatment, many persons experiencing this event will die within 48 hours. Before the 1950s, much like repair of aortic aneurysm, it was long thought impossible to correct aortic dissection surgically.<\/p>\n

\"A<\/a>
Figure in reprint of “Surgical considerations of dissecting aneurysm of the aorta<\/a>,” Annals of Surgery<\/em>, 1955
National Library of Medicine MSC 582, Box 11, FF 14<\/em><\/a><\/figcaption><\/figure>\n

Within a decade of arriving at Baylor College of Medicine, Michael E. DeBakey built a thriving surgical department. In 1955, DeBakey described his emerging experience in surgical repair of aortic dissection to the American Surgical Association and presented the results of repair in 6 patients, which were published soon thereafter as the first successful repairs of aortic dissection. DeBakey and colleagues described techniques to redirect blood back into the true channel. Notably, regardless of the anatomical location and extent of dissection, all repairs were performed on the descending thoracic aorta\u2014repair of the ascending aorta was more complicated and not yet possible. The article included a diagram classifying most of the 300 autopsy cases described in Shennan\u2019s 1934 review into 9 types of aortic dissection.<\/p>\n

\"A<\/a>
A sketch in Michael DeBakey’s European travel notebook, 1959
National Library of Medicine MSC 582, Box 2, FF 35<\/em><\/a><\/figcaption><\/figure>\n

Within the next 5 years, DeBakey and his team promoted this work through worldwide academic lectures and published more than a half dozen works on aortic dissection. By 1959, their surgical experience had grown to 45 repairs. In an article<\/a> for the American Heart Association\u2019s journal, Modern Concepts of Cardiovascular Disease<\/em>, DeBakey described two basic forms of aortic dissection, distinguished by whether the dissection is limited to the descending thoracic aorta or if it involves the ascending aorta. Because of DeBakey\u2019s many advancements in aortic surgery, repair of the ascending aorta was now possible, although it had not yet been attempted in the setting of aortic dissection. In DeBakey\u2019s hands, the majority of repairs involved dissection of the descending thoracic aorta, and he speculated that aortic dissection involving the ascending aorta is rapidly fatal, such that affected patients are unlikely to survive long enough to present for repair. For those patients with descending thoracic aortic dissection, repair is fairly straightforward; on a working tour of Europe, DeBakey participated in one such repair in which a portion of the descending thoracic aorta was replaced with a section of Dacron graft. DeBakey sketched this repair in a travel journal and noted that the patient recovered.<\/p>\n

\"sketches<\/a>
Figure in reprint of “Thoracic aorta and great vessels,” in Surgical Diseases of the Chest<\/em>, 1961
National Library of Medicine MSC 582, Box 12, FF 4-5<\/em><\/a><\/figcaption><\/figure>\n

By 1960, DeBakey had developed an early 5-type classification schema that was based on more than 50 repairs\u2014only a handful of these cases involved ascending aortic dissection. DeBakey described type II aortic dissection as being limited to the ascending aorta, whereas type I aortic dissection typically extends from the ascending aorta to the descending thoracic aorta, often continuing distally. His classification schema is from a surgeon\u2019s perspective, rather than a pathologist\u2019s. Type II aortic dissection could now be repaired by replacing the entire affected section of the ascending aorta; in contrast, repair of the far more extensive type I aortic dissection was largely to redirect blood flow into the true channel. Type III aortic dissection involved the distal aortic arch and descending thoracic aorta. Types IV and V aortic dissection involved the descending thoracic aorta, which was strictly limited in type V and extended distally to the abdominal aorta in type IV. In this era, nearly all patients with aortic dissection involving the ascending aorta would die before they could be referred for surgical repair. As a result, this early classification schema was heavily skewed toward aortic dissection involving the descending thoracic aorta, which DeBakey indicated to be roughly 90% of all dissections repaired.<\/p>\n

\"sketches<\/a>
Figure in “Surgical treatment of dissecting aneurysm of the aorta: analysis of seventy-two cases,” in Circulation<\/em>, 1961
National Library of Medicine MSC 582, Box 12, FF 4-5<\/em><\/a><\/figcaption><\/figure>\n

In late 1961, DeBakey and colleagues published data from 72 aortic dissection repairs, which represented a small portion (6%) of his team\u2019s aortic operations. Here, DeBakey discussed his early thoughts on an evolving classification model, now with 4 types, to be used to guide repair. Types I and II were as described previously, but the distinction of aortic dissection involving the distal arch and descending thoracic aorta was abandoned, causing the previously described types IV and V to move up. The classification schema pulled heavily from Shennan\u2019s 300 autopsy cases and from a review by Hirst and coauthors published in 1958, based on 505 cases from the literature (mostly autopsy cases) published from 1933 to 1954. Although only 6% of DeBakey and team\u2019s 72 repairs were for type II aortic dissection, this type of dissection constituted 29% of 723 combined cases reported by Shennan and Hirst. Likewise, DeBakey and team had only attempted repair in 9 patients with type I aortic dissection (6 of whom did not survive), but nearly 50% of the combined cases of Shennan and Hirst involved this form of extensive dissection. The lethality of types I and II aortic dissection limited DeBakey\u2019s surgical exposure to them. For those patients that survived the acute phase of a type II aortic dissection, repair was promoted in a widely available teaching film, Surgical Correction of Dissecting Aneurysm of Ascending Aorta with Aortic Valvular Insufficiency<\/em><\/a>. Notably in 1963, DeBakey and his trainees would report the first successful repair of an acute DeBakey type I aortic dissection\u2014repair of the ascending aorta was performed within 7 hours of onset and no doubt saved the young patient\u2019s life.<\/p>\n