Cardiac Medicine Certification (CMC) Practice Exam

What is a symptom of syncope often associated with third-degree heart block?

1. Nausea and vomiting

2. Increased heart rate

3. Dizziness and confusion

4. Increased respiratory rate

The correct answer is: Dizziness and confusion

Syncope, or fainting, is a temporary loss of consciousness often related to insufficient blood flow to the brain. In the case of third-degree heart block, which is a complete block of electrical signals in the heart, the heart's ability to effectively pump blood is greatly compromised. This can lead to intermittent periods of low blood pressure and reduced cerebral perfusion. Dizziness and confusion are common symptoms associated with syncope because they result from transient hypoperfusion of the brain. When the heart fails to maintain an adequate heart rate, blood may not adequately reach the brain, leading to symptoms of lightheadedness or altered mental status before a syncopal episode occurs. Nausea and vomiting, increased heart rate, and increased respiratory rate can occur in various conditions but are not directly indicative of syncope related to third-degree heart block. These symptoms might arise in response to stress or other physiological reactions but do not specifically relate to the mechanisms at play in third-degree heart block and syncope. Therefore, the presence of dizziness and confusion makes it the most relevant symptom associated with this type of heart block.