Year : 2013  |  Volume : 16  |  Issue : 2  |  Page : 126--128

Aortic dissection: To be or not to be?


Kanwar Aditya Baloria1, Achal Dhir2, Biju Pillai3, Nandini Selot1,  
1 Department of Cardiac Anesthesia, Max Healthcare Institute, Delhi, India
2 London Health Sciences Centre, London, Ontario, Canada
3 Department of Cardiac Surgery, Max Healthcare Institute, Delhi, India

Correspondence Address:
Kanwar Aditya Baloria
Department of Cardiac Anesthesia, Max Healthcare Institute, 2, Press Enclave Road, Saket, New Delhi - 110 017
India

Abstract

Patients with acute aortic dissection present with such varied symptoms that diagnosis becomes difficult. Various imaging techniques like computed tomography angiography (CTA), magnetic resonance imaging and ultrasonography are used to diagnose this entity, but they too have their limitations. We present a case, which was falsely diagnosed as acute aortic dissection by CTA, which resulted in patient undergoing sternotomy.



How to cite this article:
Baloria KA, Dhir A, Pillai B, Selot N. Aortic dissection: To be or not to be?.Ann Card Anaesth 2013;16:126-128


How to cite this URL:
Baloria KA, Dhir A, Pillai B, Selot N. Aortic dissection: To be or not to be?. Ann Card Anaesth [serial online] 2013 [cited 2021 Oct 22 ];16:126-128
Available from: https://www.annals.in/text.asp?2013/16/2/126/109761


Full Text

 Introduction



Acute Aortic dissection has been reported to be one of the most undiagnosed medical emergencies. [1] About 30% of cases remain undiagnosed until postmortem examination. [2] A mortality rate of 1% per hour in patients with untreated acute aortic dissection mandates prompt and accurate diagnosis. [3],[4] Of equal importance is identification of those who do not have aortic dissection and avoid an unnecessary surgery. Improvements in imaging technology have resulted in highly sensitive and specific diagnostic tools; however, widespread usage of these diagnostic modalities does result in an increase in the number of false positive results. These limitations have to be factored into clinical decision-making and further confirmatory testing is warranted in the hemodynamically stable patients. We present a case, which was falsely diagnosed as acute aortic dissection by computed tomography angiography (CTA), which resulted in patient undergoing sternotomy.

 Case Report



A 60-year-old male patient with a diagnosis of acute aortic dissection was referred to our center for surgical intervention. Earlier, about 12 hours before, the patient had presented to a regional health center with complaints of chest pain and breathlessness and on subsequent investigation with transthoracic echocardiography (TTE) and CTA [Figure 1], the diagnosis of acute ascending aortic dissection and massive pericardial effusion was made. On examination the patient, was conscious, co-operative, well oriented, and hemodynamically stable. The plan was to take the patient to the cardiac operating room, further investigate by transesophageal echocardiography (TEE) under general anesthesia and manage accordingly. A Board certified cardiac anesthesiologist undertook TEE. On examination, the aortic root anatomy was intact; there was no aortic regurgitation, no flaps were noticed in the aortic lumen and there was a massive pericardial effusion noticed [Figure 2] and [Figure 3]. To confirm the finding a cardiologist consultation was sought. While waiting for the cardiologist, pericardiocentesis was done and 250 ml of serous fluid was aspirated. The cardiologist repeated the TEE exam. However, he was of the opinion that there was a dissection flap in the aorta in the mid-esophageal long axis view. This apparent lack of consensus prompted the surgeon to go ahead with the surgical procedure. Standard midline sternotomy was done which revealed an inflamed granular pericardium [Figure 4]. On inspection, the aortic root looked normal so an epiaortic scanning was done, which revealed normal aortic root and ascending aorta [Figure 5]. At this point, the surgeon decided to abandon the procedure in view of the strong investigative evidence of a normal aortic root anatomy coupled with the hemodynamically stable clinical status of the patient. After closure of the sternum the patient was subjected to a CTA (64 slice) that again revealed a normal aortic anatomy. The patient was extubated uneventfully after 2 h. The pericardial histopathology and cytology of the pericardiocentesis sample revealed an acute pericarditis. The patient was managed medically and discharged from the hospital after 3 days.{Figure 1}{Figure 2}{Figure 3}{Figure 4}{Figure 5}

 Discussion



Acute aortic dissection is a potentially fatal condition that requires rapid assessment and intervention. However, despite major advances in imaging modalities and non-invasive studies, correct diagnosis is not always the rule, with misdiagnosis occurring often. [5],[6] Patients with aortic dissection present to the emergency department with a wide variety of symptoms because of involvement of multiple organ systems. Often these patients have insignificant medical history. The international registry of aortic dissection (IRAD) lists CTA as the most frequent first diagnostic test in suspected aortic dissection (61%), followed by the echocardiography (TTE and TEE) (33%), magnetic resonance imaging (MRI) (2%), and angiography in 4%, reflecting the respective availability and accessibility of these modalities. [7] MRI is a non-invasive investigation, which provides excellent resolution of valvular and aortic pathologies and coronary involvement. Although it is the most accurate, sensitive, and specific among the four diagnostic modalities, [8] its use is limited in emergency situations, particularly, in hemodynamically unstable patients, and in patients with implantable devices, such as pacemakers. Somewhat longer examination times and the need for specialized monitoring equipment further restrict the utility of MRI in favor of CTA and echocardiography in emergencies. [7],[9] Though, high sensitivity of CTA in type A aortic dissection has been reported in several studies, it is also known to have a significant percentage of false negative and false positive results. [10],[11] False negative results are due to insufficient contrast enhancement of the aortic lumen, preventing visualization of intimal flap. False positive results are due to technical factors (like streak, ring, band, and bloom artifacts) and motion artifacts. In the case discussed, the ascending aorta was covered with granular inflammatory tissue. This could have resulted in a false positive interpretation of thrombus around the aorta.

According to the American Heart Association guidelines on management of thoracic aortic disease, acute aortic dissection can be categorized into high, intermediate, and low probability risk patient according to clinical presentation. [12],[13] Patients with high-risk or intermediate risk probability are fast tracked into undergoing aortic imaging, which if negative should be followed by another secondary investigation. Cardiac sonography is listed by IRAD as the most common secondary technique. [7] In our case, although the diagnosis of acute aortic dissection was made on CTA, the patient's clinical presentation was not in accordance to the diagnosis. Therefore, a decision was made to investigate the patient by TEE under general anesthesia to reconfirm the diagnosis before proceeding with surgery. Although the initial TEE finding was suggestive of normal aortic anatomy a second opinion was sought in view of a positive CTA, which in turn led to a diagnostic dilemma, as there was a variance in opinion regarding the TEE. It is important to notice at this point that the TEE is a highly operator dependent investigative tool. The relatively high rate of false-positive readings by TEE, [10] underlines the importance of an experienced ultra-sonographer. Therefore, a routine intraoperative pre-surgical TEE examination should be performed by a trained and highly experienced cardiac anesthesiologist or cardiologist in all patients with suspected acute type A dissection.

In conclusion, a hemodynamically stable patient with conflicting results from frontline investigative tools should be subjected to an escalated level of investigative rigor prior to being subjected to an operative intervention.

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