Acute Aortic Dissection - Types, Causes, Symptoms, Diagnosis, and Treatment

Introduction

Acute aortic dissection (AAD) takes place when there is an injury in the inner layer of the most important artery of the heart- the aorta. Aorta is the biggest artery of the cardiovascular system that allows the free flow of blood in and out of the heart. During acute aortic dissection, the blood flow in the aorta seeps within the inner layers of the arteries leading it to fall apart. Sudden chest pain or sudden back pain has been linked to his condition. In some cases, acute aortic dissection can be fatal if not treated promptly. Acute aortic dissection is a rare disease but is observed more in male gender above 63 years. The first diagnosed case of acute aortic dissection that had a fatal outcome was of King George the Second of Great Britain in the year 1760.

What Are the Cardiovascular Changes That Take Place During Acute Aortic Dissection?

The aorta is composed of three layers- the innermost layer is called the intima, the middle layer is called the media, and the outermost layer is called the adventitia. During acute aortic dissection, the intima is penetrated by the blood that additionally goes into the media, splitting the two layers apart and propagating either in the forward or the backward direction. The initial split is approximately near to the aortic valve by a distance of 100 mm (millimeters). Due to this split or tear, the blood gushes in, increasing the blood pressure and thus leading to a long tear.

What Are the Causes of Acute Aortic Dissection?

Acute aortic dissection has been repeatedly linked with high blood pressure or hypertension, as well as several connective tissue malfunctioning. Inflammation of the artery, known as vasculitis, has rarely been reported to cause acute aortic dissection. Mentioned below are the causes behind the development and the occurrence of acute aortic dissection after several studies and established reports.

• Hypertension.

• Vasculitis.

• Trauma to the chest.

• Use of cocaine.

• Illicit use of Methamphetamine.

• Smoking.

• Presence of bicuspid aortic valve.

• Congenital heart disease.

• Valvular stenosis.

• Hematoma.

• Marfan syndrome.

• Ehlers-Danlos syndrome.

• Loeys-Dietz syndrome.

• Malfunctioning of connective tissues.

• Vasculitides.

• Takayasu’s arteritis.

• Giant cell arteritis.

• Polyarteritis nodosa.

• Behcet's disease.

• Turner syndrome.

• Aortic root dilatation.

• Car accidents.

• Cardiac catheterization.

• Intra-aortic balloon pump.

• Heart surgery.

• Iatrogenic causes.

• Aortic valve replacement surgery.

• Aortic regurgitation.

• Syphilis.

What Are the Signs and Symptoms of Acute Aortic Dissection?

Approximately 95 percent of individuals who suffer from acute aortic dissection present a sudden onset of pain. The pain is distinctive, with a tearing or sharp stab sensation in the back, abdomen, or chest. The pain due to the dissection can also migrate to other parts of the body. Thus the location of the pain is not exact in each and every case of acute aortic dissection. Mentioned below are the clinical features and the signs and symptoms of acute aortic dissection.

• Chest pain.

• Back pain.

• Sweating.

• Lightheadedness.

• Vomiting.

• Stroke.

• High blood pressure.

• Inter-scapular ache.

• Anterior chest discomfort.

• Pain around the pleural region.

• Acute pericarditis.

• Bleeding within the cardiac sac.

• Acute pericardial tamponade.

• Fainting.

• Congestive heart failure.

• Ischemic peripheral neuropathy.

• Paraplegia.

• Cardiac arrest.

• Paralysis.

• Ischemic of the intestine.

• Compromised renal arteries.

• Hypotension.

• Cystic medial degeneration of the cardiac walls.

• Aortic insufficiency.

• Pseudo-hypotension.

• Diastolic heart murmur.

• Dilation of the aortic annulus.

• No coaptation of the aortic leaflet.

• Intimal intussusception.

• Improper valve closure.

• Myocardial infarction.

• Pleural effusion.

• Tracheal deviation.

• Paratracheal stripe loss.

• Depression of the left bronchus.

• Obliteration of the aortic knob.

What Are the Diagnostic Tools to Determine the Presence of Acute Aortic Dissection?

Acute aortic dissection has a difficult route in order to establish diagnosis because of the several symptoms that the patient may present. The patients who are known to be hypotensive, neurologically unstable, and have abnormal pulse rates are the ones that require prompt diagnostic plans. A deep medical history, drug history, and family history are vital diagnostic factors, along with physical examination. Diagnostic imaging has proved to be of crucial importance in the diagnosis of acute aortic dissection or any other cardiovascular disease.

Mentioned below are a few of the diagnostic measures to determine the presence of acute aortic dissection depending on several factors, such as the stability of the patient and the sensitivity of the test.

• Computerized tomography of the chest.

• Iodinated contrast scan.

• Transesophageal echocardiogram.

• High-frequency ultrasound.

• Aortogram.

• Magnetic resonance imaging of the aorta.

• D-dimer blood evaluation.

• X-ray of the chest.

• Calcium sign in the aortic margin.

• Magnetic resonance angiography.

What Are the Types of Aortic Dissection?

Acute aortic dissection is classified into three categories based on the DeBakey method of classification that depends on the chronicity of the disease- ascending and descending dissection, ascending dissection, and descending dissection. This classification can be understood as DeBakey I, which includes 60 percent of dissection; DeBakey II, which includes anywhere between 10 to 15 percent of dissection, and DeBakey III, which includes approximately 25 to 30 percent of the dissection. Debakey I and DeBakey II generally occur in the proximal area of the aorta, whereas DeBakey III occurs in the distal portion of the aorta.

What Are the Treatment Options for Acute Aortic Dissection?

During a case of acute aortic dissection, the options for treatment are many, but they highly depend on the location and the classification of the dissection. Medical management is the go-to option before ending up in surgical management. Nevertheless, surgical intervention becomes crucial if the condition of the patient gets complicated even after the initiation of medical therapy. The risk of fatality is at its peak during the first few hours of dissection. Thus, acute aortic dissection is considered a medical emergency and the prime motive is to drastically cut down the force of ejection of blood from the tear and eventually from the left ventricle of the heart.

Conclusion

Acute aortic dissection is one of the most sporadic emergencies of the cardiovascular system that is characterized by shear stress over the aorta due to a tear within its inner lining. Aortogram is the gold standard to diagnose acute aortic dissection, while management of the patients must be done to decrease the blood pressure and the heart rate of the patient. The target heart rate for a positive prognosis of acute aortic dissection is 65 beats per minute with a mean arterial blood pressure of 65 mmHg (millimeters of mercury) to 75 mmHg.