Acute Aortic Syndrome – Recognition in Primary Care and Treatments

By Dr Sivaraj Pillai Govindasamy, Consultant, SingHealth Duke-NUS Vascular Centre; Department of Cardiothoracic Surgery, National Heart Centre Singapore

1/18/2022 5:52:00 PM | Defining Med

The article is contributed/written by SingHealth Duke-NUS Vascular Centre

Acute aortic syndrome covers a spectrum of potentially life-threatening aortic diseases and often requires immediate medical attention. This article outlines their clinical presentations, diagnosis and available treatments – including thoracic endovascular aortic repair (TEVAR), an emerging alternative to conventional open surgery.

INTRODUCTION

Acute aortic syndrome describes a myriad of life-threatening aortic diseases. Their presentations can be similar and clinical features are generally comparable in terms of symptoms, signs as well as epidemiological and imaging features.

The conditions include aortic dissection, aortic intramural haematoma, leaking aortic aneurysms and penetrating atherosclerotic ulcers.

Aortic dissection

Aortic dissection occurs when an injury to the innermost layer of the aorta allows blood to flow between the layers of aortic wall, forcing the layers apart. In this disease process, there is reduced or absent blood supply to the various vital organs at times.

Intramural haematoma

Intramural haematoma is defined as blood within the aortic media without the presence of an intimal tear. Its causes range from the rupture of vasa vasorum of the media or haemorrhage within an atherosclerotic plaque, to progression from a penetrating aortic ulcer. It may progress and increase in size, and is at a greater risk of rupture than dissection.

Penetrating aortic ulcers

Penetrating aortic ulcers are defined as focal intimal defects occurring at the site of atherosclerotic plaques. Progressive intimal erosion eventually results in pulsatile blood entering the media. This can lead to intramural haematomas, dissections and ruptures, as well as pseudoaneurysm and aneurysm formation.

Acute aortic syndrome - SingHealth Duke-NUS Vascular Centre

Figure 1 Acute aortic syndrome

EPIDEMIOLOGY

Aortovascular diseases have been increasing in incidence over the years. This can be attributed to the ageing population and use of surveillance scans.

These patients are usually elderly, smokers and male with a past medical history of hypertension. A lot of them are non-compliant to medications and in some cases, undiagnosed.

Rare cases that general practitioners (GPs) may encounter in the community include:

Connective tissue disorders (mainly Marfan syndrome and Ehlers-Danlos syndrome)
Bicuspid aortic valve
Annuloaortic ectasia

CLINICAL PRESENTATION AND DIAGNOSIS

Symptoms

A classical symptom is an acute tearing chest pain radiating to the back.

The location of the pain correlates with the location of pathology. Pain located anteriorly in the chest or in the neck and jaw typically denotes ascending aortic involvement. In contrast, pain in the back and abdomen suggests descending aortic pathology.

Patients are usually severely hypertensive. If a patient is hypotensive, this is a bad sign and the risk of death can be imminent.

Radiographic features

Chest X-ray usually shows widened mediastinum. Computed tomography (CT) imaging is readily available in most centres, and has high sensitivity and specificity. Most importantly, it is a quick scan.

Alternatives include magnetic resonance imaging (MRI) and transoesophageal echocardiography; however, these may not be readily available.

In many emergency departments, transthoracic echocardiography is readily available which can give a clue to the diagnosis.

CT angiography with dissection of aortic arch - SingHealth Duke-NUS Vascular Centre

Figure 2 CT angiography obtained in a patient with dissection of the aortic arch is clearly demonstrated on axial imaging (left panel). Involvement of the brachiocephalic (B) and left subclavian (S) ostia is apparent on a more cranial axial image (middle panel), whereas the origin of the left common carotid artery (C) is spared.

A multiplanar image reformatted in an oblique sagittal plane (right panel) nicely renders false lumen in the brachiocephalic (long arrow) and left subclavian (short arrow) arteries.

TREATMENT OPTIONS

The diagnosis of the aortic pathology determines its management.

Not all conditions require immediate or early interventions. In mild cases, patients are serially monitored with the use of scans.

Blood pressure control helps slow the disease process, and stopping smoking further helps the patient’s cause.

For acute aortic syndrome involving the ascending aorta

Aortic pathology involving the ascending aorta is treated with emergency high-risk open surgery.

Emergency surgery includes the replacement of the ascending aorta under deep hypothermic circulatory arrest.

Deep hypothermic circulatory arrest is a surgical technique that induces deep medical hypothermia. It involves cooling the body to temperatures between 16-25°C and stopping blood circulation and brain function for 45-60 minutes.

During this time, the ascending aorta is excised, and synthetic graft is sutured to the proximal aortic arch. After which, circulation is resumed and rest of the surgery continues.

At the normal body temperature of 37°C, only several minutes of stopped blood circulation causes changes within the brain leading to permanent damage. Lowering the body temperature extends the time interval in which such stoppage can be survived.

At a brain temperature of 16-18°C, blood circulation can be safely stopped for 45-60 minutes. There is an increased incidence of brain injury at time intervals longer than 45-60 minutes.

For acute aortic syndrome sparing the ascending aorta

More distal disease sparing the ascending aorta is treated with medical therapy.

Patients with acute aortic syndrome sparing the ascending aorta were usually offered high-risk conventional open surgeries in the past. Today, a selected group of patients are suitable for thoracic endovascular aortic repair (TEVAR).

TEVAR – AN ALTERNATIVE TO CONVENTIONAL OPEN SURGERY
Benefits of TEVAR TEVAR has emerged as an alternative to conventional open surgery. Many of the patients who suffer from aortovascular conditions are elderly, frail and have a number of medical conditions – including patients who previously would not have qualified for any intervention. TEVAR thus increases the population of patients who can be treated. The TEVAR procedure Patients are typically under general anaesthesia, and the TEVAR procedure is performed in a hybrid operating theatre under X-ray guidance. During the procedure, a tube or catheter is inserted into the femoral artery in the groin. A wire is guided through the artery into the aorta. A stent graft is delivered in a collapsed state through the catheter, positioned accurately using X-ray guidance. The stent graft is then expanded to span and cover the site of aortic injury. As a result, the stent graft lines and reinforces the torn aortic wall to ensure continuity of blood flow and prevent further bleeding. This procedure usually takes about one to three hours. Post-procedure recovery and care Patients typically stay in the hospital for three to four days and can resume all regular activities within a month. Complex cases may require a longer procedure time and hospital stay. Follow-up is lifelong with serial scans. TEVAR vs open surgery The main procedural risks of TEVAR include catastrophic paraplegia which can be mitigated with spinal drain insertion and permissive hypertension. Other risks include bleeding, infection and stroke. Overall, despite these risks, it provides the advantage of being less invasive than open surgery and requiring a shorter recovery time. It also gives hope to patients who are at high or prohibitive surgical risk. Continued enhancements In the past, the femoral artery in the groin was accessed using a surgical incision and subsequently repaired post-procedure. However, in recent times, percutaneous closure devices have had success in furthering the procedure. Today, the painful surgical incision in the groin has been replaced by percutaneous closure devices. The TEVAR procedure is evolving into a truly minimally invasive surgery. In the last few years, TEVAR technology has had further enhancements. Stents can be custom-built for each patient’s vascular anatomy. However, the time needed to build each customised stent is about four to six weeks.

TEVAR – AN ALTERNATIVE TO CONVENTIONAL OPEN SURGERY

Benefits of TEVAR TEVAR procedure - SingHealth Duke-NUS Vascular Centre

TEVAR has emerged as an alternative to conventional open surgery.

Many of the patients who suffer from aortovascular conditions are elderly, frail and have a number of medical conditions – including patients who previously would not have qualified for any intervention. TEVAR thus increases the population of patients who can be treated.

The TEVAR procedure

Patients are typically under general anaesthesia, and the TEVAR procedure is performed in a hybrid operating theatre under X-ray guidance.

During the procedure, a tube or catheter is inserted into the femoral artery in the groin. A wire is guided through the artery into the aorta. A stent graft is delivered in a collapsed state through the catheter, positioned accurately using X-ray guidance.

The stent graft is then expanded to span and cover the site of aortic injury. As a result, the stent graft lines and reinforces the torn aortic wall to ensure continuity of blood flow and prevent further bleeding.

This procedure usually takes about one to three hours.

Post-procedure recovery and care

Patients typically stay in the hospital for three to four days and can resume all regular activities within a month. Complex cases may require a longer procedure time and hospital stay. Follow-up is lifelong with serial scans.

TEVAR vs open surgery

The main procedural risks of TEVAR include catastrophic paraplegia which can be mitigated with spinal drain insertion and permissive hypertension. Other risks include bleeding, infection and stroke.

Overall, despite these risks, it provides the advantage of being less invasive than open surgery and requiring a shorter recovery time. It also gives hope to patients who are at high or prohibitive surgical risk.

Continued enhancements

In the past, the femoral artery in the groin was accessed using a surgical incision and subsequently repaired post-procedure. However, in recent times, percutaneous closure devices have had success in furthering the procedure.

Today, the painful surgical incision in the groin has been replaced by percutaneous closure devices. The TEVAR procedure is evolving into a truly minimally invasive surgery.

In the last few years, TEVAR technology has had further enhancements. Stents can be custom-built for each patient’s vascular anatomy. However, the time needed to build each customised stent is about four to six weeks.

PROGNOSIS

Up to 30% of these acute aortic syndrome cases may have serious complications at the time of presentation.

These can include:

Aortic rupture leading to immediate death
Haemopericardium with tamponade features
Acute severe aortic valve dysfunction
Coronary artery dissection and/or occlusion

In the case of left main occlusion, there is almost always instant death
In the case of right coronary occlusion/dissection, the patient presents with massive inferior myocardial infarction with bradycardia

Aortic branch dissection and/or occlusion that can lead to strokes
End-organ ischaemia or infarction – these can present as acute renal failure and bowel/limb ischaemia

The National Heart Centre Singapore cardiovascular team evaluates and follows up with these patients to determine the timing and type of intervention. Those with extensive aortic disease may require a combination of both open and endovascular surgery.

REFERENCES

A.C. Braverman, R.W. Thompson, L.A. Sanchez. Braunwald’s Heart Disease: A Textbook of Cardiovascular Medicine. Elsevier, Philadelphia, PA (1961), pp. 1309-1337
The role of imaging in aortic dissection and related syndromes. Baliga RR, Nienaber CA, Bossone E, Oh JK, Isselbacher EM, Sechtem U, Fattori R, Raman SV, Eagle KA. JACC Cardiovasc Imaging. 2014 Apr;7(4):406-24. doi: 10.1016/j.jcmg.2013.10.015.
Acute aortic syndromes: diagnosis and management, an update. Bossone E, LaBounty TM, Eagle KA. Eur Heart J. 2018 Mar 1;39(9):739-749d. doi: 10.1093/eurheartj/ehx319.

Dr Sivaraj Pillai Govindasamy is a Consultant at the Department of Cardiothoracic Surgery, National Heart Centre Singapore. His interests include coronary artery bypass grafting surgery, extracorporeal membrane oxygenator implantation, valvular heart disease and aortic diseases.

GPs can call the SingHealth Duke-NUS Vascular Centre for appointments at the following hotlines:

Singapore General Hospital: 6326 6060
Changi General Hospital: 6788 3003
Sengkang General Hospital: 6930 6000
KK Women’s and Children’s Hospital: 6294 4050
National Heart Centre Singapore: 6704 2222