Carcinoid Syndrome

Question 1

What are the cardiac manifestations of carcinoid

syndrome?

Answer 1

Cardiac problems associated with carcinoid syndrome are usually due to fibrosis of the endocardium. Pulmonic stenosis and tricuspid regurgitation are often present.

Question 2

How can carcinoid syndrome mimic an allergic

reaction?

Answer 2

Some carcinoid tumors can release histamine and kallikrein which can result in bronchospasm, tachycardia, and hypotension.

Question 3

What medications relieve the diarrhea associated

with carcinoid syndrome?

Answer 3

Serotonin antagonists such 5-HT3 antagonists relieve the diarrhea in most patients with carcinoid syndrome.

Question 4

What anesthesia related events should be avoided in

the patient with carcinoid syndrome?

Answer 4

Sympathomimetics such as ephedrine and histamine-releasing drugs such as morphine, succinylcholine, thiopental, and atracurium should be avoided if possible as they can trigger the
release of hormones from the tumor as well. Hypotension should also be avoided in patients with carcinoid tumors as it can be a trigger for the release of hormones from the tumor.

Question 5

What is carcinoid syndrome and what are its most

common symptoms?

Answer 5

About 1 in 5 patients with a carcinoid tumor will experience carcinoid syndrome which results from the massive release of hormones such as serotonin. The two most common symptoms
are flushing and diarrhea.

Question 6

What are the three most common locations for a

carcinoid tumor?

Answer 6

The bronchus, jejuno-ileum, and the colon.

Question 7

What types of substances can be released by a

carcinoid tumor?

Answer 7

Carcinoid tumors most notably release serotonin and prostaglandins, but also release a wide range of peptides including gastrin, insulin, substance P, glucagon, growth hormone, and corticotropin.

Question 8

What diagnostic test is usually indicative of carcinoid syndrome?

Answer 8

Carcinoid syndrome can be confirmed by detection of urinary 5-hydroindoleacetic acid.

Question 9

Not all patients with a carcinoid tumor experience
side effects from the hormones released from the
tumor. Why not?

Answer 9

Usually, hepatic first-pass metabolism eliminates the hormones from the circulatory system before they can exert any deleterious effects.

Question 10

Carcinoid syndrome often causes right-sided cardiac lesions, but typically spares the left-side unless an intracardiac shunt is present. What accounts for this?

Answer 10

Elevated serotonin levels can result in right-sided heart failure. The lungs metabolize serotonin, thus sparing the left side of the heart. The presence of a right-to-left shunt, however, would expose the left side of the heart to the serotonin and cause leftsided heart symptoms.

Question 11

In which tissues does serotonin act as a vasodilator?

Answer 11

Serotonin acts as a vasoconstrictor in all tissues except the heart and skeletal muscle, where it acts as a vasodilator. The renal and pulmonary systems are the most sensitive to the vasoconstrictive effects of serotonin.