Hypertrophic Cardiomyopathy

Diagnosis

Several tests can determine hypertrophic cardiomyopathy.

History and Physical Exam

The physician will first ask many questions about the patient's history, including symptoms, prior tests and family history. This is very important so that the patient's functional status can be determined. A physical examination concentrating on the heart will then be performed to determine information on the heart's size and evidence of obstruction or valve leakage.

Blood Tests

These tests can be used to check for specific gene mutations. There is much research in molecular genetics underway at the Mayo Clinic. A special program is looking specifically at gene mutations which may occur in patients with hypertrophic cardiomyopathy.

Hundreds of mutations have been uncovered in several genes. There is a tremendous interest in how specific mutations may impact the course of the disease. Because research is rapidly advancing, blood will also be stored so that further analysis can be done as new discoveries are being made. This may have important implications for first-degree relatives in the future.

Chest X-rays

These X-rays allow the heart size and position to be viewed.

Echocardiograms ("ECHO")

This is a noninvasive sound wave imaging test that allows the physician to observe the heart as it is beating. It measures muscle thickness, degree of obstruction, chamber size, valve movement and blood flow. The test also determines pressures inside the heart chambers and major vessels. Medications that change the pressures inside the heart can be given during ECHO. This allows the physician to observe the change in the degree of obstruction when the heart is stressed.

Electrocardiograms (ECG) and Holter Monitor

These are graphic records of the electrical activity in the heart that generates a heart beat. A 12-lead electrocardiogram provides information about the heart rhythm (taken over 10 seconds) and indirectly about the size of the heart. A Holter monitor is worn for 24 to 72 hours and records the heart rhythm over this entire period of time. In hypertrophic cardiomyopathy it is not uncommon to have irregular heart rhythms called arrhythmias. Some specific arrhythmias may predict future events.

Exercise Test ("TMET")

Several exercise tests are available depending on the information the physician needs. An exercise test will help quantitate activity tolerance and screen for arrhythmias. The change in blood pressures during exercise also has implications for an individual's prognosis.

With an O₂ consumption test, the patient will be asked to exercise while breathing into a mask so that the amount of oxygen that the body uses can be measured.

With a thallium scan, a harmless radioactive solution is injected into a vein during exercise and a camera is used to look at blood flow to the heart muscle.

ECHO can be done immediately after exercise to get a better understanding of how severe the obstruction may be under stress.

Heart Catheterization ("Angio" or "Cath")

This invasive procedure is done in the hospital, but usually as an outpatient procedure. Thin flexible catheters are passed through a peripheral artery from the groin area into the chambers of the heart. The catheters are used to measure pressures inside the heart, deliver medications into the heart, and directly deliver dye into the heart chambers and vessels. The dye can be seen with X-ray imaging as it is moving through the heart and vessels and outlines any blockages in the arteries.

This test is also used to determine the heart's response to a temporary pacemaker. Surprisingly, there is very little pain involved — it is usually just due to the numbing medication given at the start of the procedure. The patient is required to lie flat for several hours after the procedure to prevent bleeding from the puncture site.