Avoiding an aortic catastropheJune 11, 2019
55-year-old Satish (name changed) suddenly started having chest pains and was rushed to a local hospital in Pallakad, Kerala. As an ex-army man, he had never experienced such pain and his family assumed he was having a heart attack. However, all initial tests that were run were negative and an echo cardiography was performed. The echo showed an aortic dissection and Satish was transferred to Amrita Hospital, Kochi, which has a dedicated Centre for Aortic Diseases and Marfan Syndrome. Here he was immediately rushed to the operation theatre without further ado by the medical team led by Dr Praveen Varma, Head of Cardiovascular and Thoracic Surgery.
An aortic dissection is a tear in the inner lining of the aorta, just above the aortic valve, and results due to increased stress within the walls of the aorta. Type A aortic dissection such as this one is a life-threatening medical emergency requiring immediate surgery, without which mortality can be almost 100%. Once the aorta dilates from the normal range of 2.5-3 cm to 4.5-5 cm, it is likely to dissect. Right before the team started operating on Satish, his aortic wall ruptured outside However, the procedure was already underway, and the medical team remained unfazed as they proceeded with the aortic root replacement surgery, which is a complex surgery often taking 8-10 hours.
This procedure involves multiple steps. The first step involves a surgical technique called total circulatory arrest in which the body is cooled to less than 18°C before cutting off blood circulation to the whole body. The cool temperatures allow the brain to survive the circulatory arrest, however, brain activity must be closely monitored to ensure that the cool temperatures keep the brain quiescent throughout the surgery. This is critical while performing delicate procedures on large blood vessels such as in this case. The patient is typically connected to a cardiopulmonary bypass, an external heart-lung machine, which drains the blood out of the body and cools it to less than 18 °C. Brain activity is monitored by monitoring blood flow to the brain by Near Infrared Spectroscopy. Once the brain function has stopped, the actual aortic root replacement surgery can commence. This was done following the Bentall procedure, in which the aortic valve, the aortic root and the ascending aorta are replaced with a composite graft, and the coronary arteries are then re-implanted into the new graft. Once the replacement surgery is completed, the blood is warmed again, and the patient is then returned to normal blood flow and brain activity.
Satish’s surgery went well, and he was kept in the ICU for 2 days and discharged 8 days post-surgery. Now he is on strong anti-hypertensive drugs, which will be his lifelong companions. He is also given a blood thinner to ensure the proper functioning of the new artificial mechanical valve.
While aortic dissection and rupture are relatively uncommon, major risk factors are uncontrolled high blood pressure, atherosclerosis, cocaine abuse, bicuspid aortic valve, or genetic diseases such as Turner’s syndrome or Marfan syndrome. Patients with Turner’s syndrome have a missing or structurally altered X-chromosome resulting in many abnormalities including aortic valve defects. Marfan syndrome is caused due to an autosomal dominant mutation in the FBN1 gene which encodes a protein called fibrillin 1. This protein is an extracellular matrix glycoprotein that provides structural support to connective tissue throughout the body. Patients with Marfan syndrome have typical visual clinical features of elongated limbs, fingers and toes, and scoliosis. Marfan syndrome may also affect other organs including eyes, bones, lungs, and heart. Marfan syndrome patients are at a high risk of aortic dilation, aortic aneurysm and mitral valve prolapse, and aortic dissection which may well be the most serious of all the complications associated with Marfan syndrome.
In 2016, a special Centre for Aortic Diseases and Marfan Syndrome was started at Amrita Hospital, Kochi. This is the only such center in India that is dedicated to patients with Marfan syndrome and other aortic diseases. It comprises of a multidisciplinary team including cardiologists, surgeons, ophthalmologists, geneticists, obstetricians as well as radiologists. These doctors together offer comprehensive care including genetic counselling and associated medical support as required. The cardiovascular surgeons are skilled to deal with the most serious complications like aortic ruptures. Today over 50 patients are registered with this clinic and undergo regular screenings every 6 months. In case clinical observations indicate that the aorta is dilating, elective aortic root replacement may also be offered.
According to Dr Varma, even though aortic diseases and acute aortic syndromes are more catastrophic and complicated, they are not given much importance in India and are often overlooked and misdiagnosed as heart attacks. Should an ECG rule out a heart attack, consider performing an echo to check for aortic dissection. Patients with aortic dissection should immediately be transferred to the nearest hospital with surgical expertise.