Guarding Against Syncope

 

Changing of the guard ceremonies take place in many countries, including the United States (Arlington Cemetery), the United Kingdom (Buckingham Palace), China (Tiananmen Square), Greece (Syntagma Square), Canada (Parliament Hill), India (palace of the President) and Monaco (the Prince’s Palace). Typically, these ceremonies involve military personnel with one group switching place with another and taking over the protection of a significant national monument. The guard changes are elaborate, precisely choreographed and viewed by tourists. Many times, the soldiers stand motionless for hours in the hot sun. Sometimes, they pass out. Passing out, fainting, blacking out or losing consciousness is called syncope. What causes syncope and how can it be diagnosed efficiently?

 

Syncope is an abrupt and transient loss of consciousness due to lack of blood flow to the brain followed by a quick recovery. Syncope must be distinguished from seizure, low blood sugar, drug or alcohol intoxication or psychiatric conditions all of which may cause a person to pass out but are not due to lack of brain blood flow. Syncope is extremely common, accounting for 3% to 6% of all emergency room visits. In people over 45 years of age, 25% have reported an event. The incidence of syncope has three peaks, ages 20, 60 and 80. Women are more likely than men to pass out. 

 

The causes of syncope can be divided into nonlife-threatening processes and severe, potentially life-limiting diseases. Benign causes include the following. 

Vasovagal syncope: passing out due to an unpleasant stimulus (pain, sight of blood, stress, medical procedure)

Situational syncope: passing out after coughing, sneezing, swallowing, urinating

Orthostatic hypotension: passing out after standing, blood pressure falls on standing

Dehydration

Even though these causes usually are not life-threatening, there is significant morbidity such as falls and fractures.

Potentially life-threatening etiologies include:

Bradyarrhythmias: slow heart rate (heart rate less than 40 beats per minute or no heart beat for 3 or more seconds) or heart block (electric pathway between upper and lower chambers disrupted).

Tachyarrhythmias: ventricular tachycardia (irregular heart rhythm from the lower chambers)

Heart attack

Blood clot in the lungs

Structural heart disease, obstruction to the blood flow from the lower chamber: thickened heart muscle or blockage in the aortic valve  

The prognosis in cardiac related syncope is much worse than the other types. With vasovagal syncope, the prognosis is the same as the general population. In both groups, 60% are alive 15 years after the event. In patients with a cardiac cause, only 20% are alive at 15 years. Therefore, it is important to determine whether the cause of syncope is due to a heart related issue.

 

Syncope is a symptom and finding an accurate diagnosis is imperative. However, trying to determine the cause of a syncopal episode is notoriously difficult. Even in the best of circumstances a diagnosis can be attributed in only about 50% of cases. There are many diagnostic tests that can be ordered including, CT scan, MRI, ambulatory external monitor (one to three days or one to four weeks), implantable cardiac monitor, stress test, catheterization, ultrasound of the neck arteries, electrophysiology study, tilt table test. One or more of these tests may be appropriate in the right situation, but not every patient with syncope needs multiple tests.  The items with the greatest diagnostic yield are the history, the physical exam, an electrocardiogram (EKG) and an echocardiogram (ultrasound of the heart). These should be done on all patients and further tests can be ordered as needed.  The history, the circumstances surrounding the event, is the key.

If the syncope occurs:

With an unpleasant stimulus (for example, a needle stick), think vasovagal.

With coughing, swallowing, urinating, defecating, think situational.

In any position (especially while sitting or lying down), think cardiac.

With standing up, think orthostatic hypotension.

With nausea, sweating or flushing, think vasovagal.

With palpitations or chest pain, think cardiac.

With history of heart disease or male or older age, think cardiac.

With blood pressure drop on standing, think orthostatic hypotension.

With associated head or facial trauma, think cardiac.

With normal physical exam, EKG and echocardiogram (structural heart disease less likely), think noncardiac cause.

After evaluating these four items, a risk assessment can be made, further testing ordered tailored to the situation and appropriate treatment begun.

 

So, if you find yourself watching a changing of the guard in the hot mid-day sun and you pass out, take it seriously. Head to the nearest emergency room immediately, even if you are low risk and even if you feel perfectly normal after recovering.