Painless Ascending Aortic Dissection Presenting as Hypothermia, Shock and Atrial Fibrillation Mimicking Sepsis
Ashmi Thomas *1, Abubaker Mohammed 1, Rajesh Kumar 1
*Correspondence to: Ashmi Thomas, Emergency medicine, Darlington Memorial Hospital,
Darlington, GBR.
© 2026 Ashmi Thomas. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Received: 27 July 2026
Published: 01 August 2026
DOI: https://doi.org/10.5281/zenodo.21802023
Abstract
Acute aortic dissection is a life-threatening cardiovascular emergency that typically presents with sudden, severe chest or back pain. However, atypical painless presentations can delay diagnosis and increase mortality. We report the case of a 66-year-old woman who presented with profound hypothermia, refractory shock, atrial fibrillation with rapid ventricular response, and severe metabolic acidosis, leading to an initial diagnosis of septic shock. Despite aggressive resuscitative measures, her haemodynamic status continued to deteriorate. Urgent CT angiography subsequently demonstrated a catastrophic ascending thoracic aortic dissection with rupture, haemopericardium, and cardiac tamponade. The patient suffered pulseless electrical activity arrest and died despite resuscitative efforts. This case highlights the importance of maintaining a high index of suspicion for acute aortic syndromes in patients with unexplained haemodynamic instability, persistent lactic acidosis, or failure to respond to standard sepsis management, even in the absence of chest pain. Early recognition and prompt definitive imaging remain essential to improve outcomes in this rapidly fatal condition.
Categories: Emergency Medicine, Internal Medicine, Cardiac/Thoracic/Vascular Surgery
Keywords: asymptomatic aortic dissection, atrial fibrillation (af), cardiac tamponade, haemopericardium, serum lactate.
Introduction
Acute aortic dissection is a life-threatening vascular emergency with highly variable clinical presentations. Although severe chest or back pain is classically described, painless dissections may occur and contribute to delayed diagnosis and increased mortality. We describe the case of a 66-year-old woman presenting with hypothermia, refractory shock and atrial fibrillation, initially treated as presumed sepsis. CT angiography later demonstrated catastrophic ascending thoracic aortic rupture with haemopericardium and cardiac tamponade secondary to acute aortic dissection. The patient deteriorated rapidly and died despite resuscitative efforts. This case highlights the importance of considering acute aortic syndromes in patients with unexplained haemodynamic instability and rising lactate despite treatment
Case Presentation
A 66-year-old Chinese woman with a history of previous thoracic endovascular aortic stent graft placement for aortic dissection was brought to the emergency department by ambulance on 15 April 2026 after becoming acutely unwell while travelling by train. According to relatives, she had felt generally unwell since the morning. During the journey she became clammy, weak, and increasingly unwell, prompting fellow passengers to call the emergency services.
On arrival, she denied chest pain, back pain, abdominal pain, shortness of breath, cough, or vomiting. Language barriers limited history taking initially, as collateral information was obtained later from her niece.
Initial examination demonstrated an alert but clammy patient. Her temperature was 35.6°C, heart rate 156 beats/min, blood pressure 90/50 mmHg, respiratory rate 16 breaths/min, and oxygen saturation was maintained on room air. Cardiovascular examination revealed atrial fibrillation with rapid ventricular response. Trachea was central, chest auscultation demonstrated good bilateral air entry without focal crepitations, and abdominal examination was soft and non-tender.
Initial venous blood gas analysis demonstrated pH 7.33, pCO? 4.6 kPa, bicarbonate 18.9 mmol/L, base excess -6.7, and lactate 6.0 mmol/L, consistent with metabolic acidosis. Initial investigations included routine blood tests, ECG, chest radiography, and venous blood gas analysis. The ECG demonstrated fast atrial fibrillation, which subsequently reverted spontaneously to sinus rhythm.
Given the combination of hypotension, elevated lactate, hypothermia, and raised inflammatory markers, septic shock was considered the leading diagnosis. The patient received intravenous crystalloid fluids, broad-spectrum intravenous antibiotics, continuous monitoring, and supportive management while awaiting investigation results.
Despite treatment, the patient’s condition progressively deteriorated. Repeat venous blood gas analysis approximately four hours later demonstrated worsening metabolic acidosis with pH 7.14, bicarbonate 11.0 mmol/L, base excess -15.3, and lactate 13.8 mmol/L, despite ongoing fluid resuscitation. Persistent hypotension and rapidly rising lactate prompted intensive care review.
Following collateral history revealing previous thoracic aortic intervention, urgent CT angiography of the aorta was requested. To expedite diagnosis, the patient was transferred directly from the resuscitation area to CT under continuous monitoring. CT angiography demonstrated a catastrophic ascending thoracic aortic rupture with large-volume haemopericardium, cardiac tamponade, and active contrast extravasation from the mid tubular ascending thoracic aorta secondary to subintimal dissection with wall rupture. A previously placed thoracic endovascular stent graft was noted in the descending thoracic aorta without evidence of endoleak or graft-related complication (Figures 1-4).
Immediately following CT imaging, the patient developed worsening haemodynamic instability with bradycardia before progressing to pulseless electrical activity cardiac arrest. Advanced life support was initiated immediately. The patient briefly achieved return of spontaneous circulation but experienced recurrent cardiac arrests despite ongoing resuscitative efforts, including adrenaline administration, advanced airway management, arterial line placement, and continued cardiopulmonary resuscitation.
Subsequent arterial blood gas analysis demonstrated profound metabolic acidosis (pH 6.81, lactate 15.9 mmol/L, bicarbonate 6.3 mmol/L), consistent with catastrophic circulatory failure. Following multidisciplinary discussion, the extensive ascending aortic rupture with cardiac tamponade was considered non-survivable. Resuscitation was therefore discontinued, and the patient was pronounced deceased. The final radiology report confirmed acute ascending thoracic aortic rupture with haemopericardium, cardiac tamponade, active haemorrhage, and retroperitoneal haematoma secondary to acute aortic dissection.
Discussion
Acute aortic dissection is a rare but life-threatening cardiovascular emergency with mortality increasing by approximately 1-2% per hour if left untreated. Prompt diagnosis and early surgical intervention are essential to improve survival. Although the classical presentation includes sudden, severe tearing chest or back pain, the clinical spectrum is broad, making diagnosis challenging in atypical cases. [1-3]
Painless acute aortic dissection is uncommon, accounting for approximately 6-17% of cases in published series. Patients without pain are more likely to experience delayed diagnosis and higher mortality because the condition mimics other medical emergencies. Delayed recognition has consistently been associated with worse clinical outcomes, highlighting the importance of maintaining a high index of suspicion even in atypical presentations. Previous reports have described presentations with syncope, stroke, heart failure, myocardial infarction, cardiac arrest, or isolated shock rather than chest pain. [4-8]
Our patient presented with profound hypothermia, refractory shock, atrial fibrillation, metabolic acidosis, and elevated inflammatory markers, leading to an initial diagnosis of septic shock. Similar cases of painless aortic dissection associated with atrial fibrillation have been described, but the combination of hypothermia, shock, and previous thoracic aortic intervention is particularly unusual and illustrates the potential for diagnostic anchoring. [9-10]
Clinicians should maintain a high index of suspicion for acute aortic syndromes in patients with unexplained haemodynamic instability, persistent lactic acidosis despite resuscitation, or evidence of cardiac tamponade, even in the absence of chest pain. Early CT angiography remains the diagnostic investigation of choice when the diagnosis is uncertain, and prompt diagnosis is essential to improve survival. [11-13]
Conclusions
This case highlights the diagnostic complexity of painless acute ascending aortic dissection, a rare but frequently fatal presentation that may mimic more common conditions such as septic shock. In this patient, profound hypothermia, refractory hypotension, atrial fibrillation and worsening lactic acidosis led initially to a diagnosis of sepsis, delaying recognition of the underlying acute aortic catastrophe. The subsequent identification of ascending aortic rupture with haemopericardium and cardiac tamponade underscores the devastating consequences of missed or delayed diagnosis.
Clinicians should maintain a high index of suspicion for acute aortic syndromes in patients with unexplained haemodynamic instability, persistent shock despite appropriate treatment, and rising lactate levels, particularly when risk factors such as previous aortic intervention are present. Early consideration of alternative diagnoses and prompt definitive imaging remain crucial to improving outcomes in this time-critical condition.
Additional Information
Author Contributions
All authors have reviewed the final version to be published and agreed to be accountable for all aspects of the work.
Concept and design: Ashmi Thomas, Abubaker Mohammed, Rajesh Kumar
Acquisition, analysis, or interpretation of data: Ashmi Thomas, Abubaker Mohammed
Drafting of the manuscript: Ashmi Thomas
Critical review of the manuscript for important intellectual content: Ashmi Thomas, Abubaker Mohammed, Rajesh Kumar
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