Laboratory Tests

High Blood Pressure

Blood pressure ( BP) is recorded as two numbers, with a ratio like this: 120/80 mmHg. The top number, called systolic blood pressure, measures the pressure in the arteries when the heart beats. The lower number, called diastolic blood pressure, measures the pressure in the arteries between heartbeats. High blood pressure is defined as over 140/90 on at least two separate occasions on separate days. Blood pressure should be measured at each doctor’s office visit starting at age 18 years, but at least every 2 years. Target blood pressure is 120/80 mmHg or less, regardless of age. Many people have high blood pressure ( HBP) for years. If left untreated, it can lead to coronary heart disease, heart attack or stroke. A higher percentage of men than women have HBP until age 45. From ages 45–64, the percentage of men and women is similar. After that, a much higher percentage of women have HBP than men.

For persons over age 50, systolic blood pressure is more important than diastolic blood pressure as a cardiovascular disease risk factor. Starting at 115/75 mmHg, cardiovascular disease risk doubles with each increment of 20/10 mmHg throughout the BP range. Those with systolic BP of 130–139 mmHg or diastolic BP of 80–89 mmHg should be considered prehypertensive and require health-promoting lifestyle modifications to prevent cardiovascular disease.

High LDL cholesterol
LDL (low density lipoprotein), the so-called “bad” cholesterol, contributes to the artery blockages (plaques). Most people should aim at an LDL cholesterol level of 100 mg/dL or lower. If you are at very high risk of developing cardiovascular disease, or if you have already had a heart attack, you may need to aim at an LDL level below 70 md/dL.

Low HDL cholesterol
HDL (high density lipoprotein) the so-called “good” cholesterol is a reverse-transport protein: it removes cholesterol from the arteries and takes it to the liver where it can be passed out of the body. High levels of HDL cholesterol lower your risk of developing cardiovascular disease. An HDL level of 60 mg/dL and over is considered excellent, providing you optimal protection.

High Triglyceride level
Triglyceride is the most common type of fat in the body. Many people who have heart disease or diabetes have high triglyceride levels. Normal triglyceride level is less than 150 mg/dL.

High Total cholesterol is a measure of LDL cholesterol, HDL cholesterol and other lipids. The desirable level of total cholesterol is less than 200mg/dL.

Diabetes or pre-diabetes
Diabetes mellitus is defined as a fasting blood glucose of greater than 125 mg/dL or more. Diabetes (elevated blood sugar) increases your risk for developing cardiovascular disease. There are two main types of diabetes. Type 1 diabetes is usually first diagnosed in children and young adults. Type 2 diabetes is the most common form and can develop at any age. If you have diabetes, no matter which type, it means that you have too much glucose in your blood, and it can lead to serious health issues. Diabetes and heart disease share similar risk factors (high cholesterol level, high blood pressure, obesity).

People with a fasting blood glucose level between 100 mg/dL and 125 mg/dL have an increased risk for developing Type 2 diabetes. If they do not make lifestyle modifications, they will likely develop diabetes within the next 10 years. Pre-diabetes is reversible. If the affected person loses weight, maintains a healthy diet and increases his or her physical activity, he or she may be able to prevent progression to diabetes.

Obesity
Achieving and maintaining a healthy weight is one of the best things you can do for your heart. Weight gain is linked to increased blood cholesterol, blood pressure, and risk for diabetes. Overweight or obese individuals, especially if they have risk factors for heart disease such as high cholesterol, high blood pressure, or high blood glucose, will benefit from even a small amount of weight loss. Prevention of more weight gain is an important place to start.

Metabolic syndrome
Metabolic syndrome is a cluster of abnormalities that occur together, increasing your risk of developing heart disease, stroke, and diabetes. The group of metabolic risk factors includes the following syndromes:

• Abdominal obesity (excessive fat tissue in and around the abdomen), waist circumference of greater than 40 inches for men and 35 inches for women
• Fasting blood triglycerides greater than 150 mg/dL
• Blood HDL cholesterol less than 40 mg/dL for men and less than 50 mg/dL for women
• Fasting blood glucose ( blood sugar) greater than 100 mg/dL
• Elevated blood pressure (130/85 mmHg or higher)

Metabolic syndrome is identified if you have three or more of these factors present.

Arrhythmia
An abnormal heart rhythm is a change in either the speed or the pattern of the heartbeat — the heart may beat too slowly, too rapidly or irregularly. A heart which beats too fast or too slow can cause:

• Lightheadedness or dizziness
• Palpitations (skipping, fluttering or pounding in the chest)
• Fatigue
• Chest pressure or pain
• Shortness of breath
• Fainting spells

Sometimes there are no symptoms at all. Left untreated, certain abnormal heart rhythms can cause death. On the other hand, some arrhythmias are common and not associated with any untoward conditions, so called benign arrhythmias.

Coronary Artery Disease
The most common cause of heart disease is narrowing of the coronary arteries, the blood vessels that supply oxygen-rich blood to the heart. This is called coronary artery disease and it is a major reason for heart attacks. When the coronary arteries are blocked, oxygen cannot get to the affected area of the heart and if the blockage lasts for more than a few minutes, permanent damage can occur. Reduced coronary blood flow from a partial blockage can cause angina (chest pain), shortness of breath and other symptoms. When a complete blockage occurs, it can cause a heart attack.

Heart Attack
Heart Attack happens when the coronary artery, the blood vessel that supplies oxygen-rich blood to the heart, is completely blocked and oxygen cannot get to the affected area of the heart. Heart attack warning signs include:

• Tightness or a feeling of pressure in the chest
• Pain or heaviness radiating down the left arm, or up to the neck or jaw
• Pain that goes through the chest to the back, between the shoulder blades
• Breaking into a cold sweat
• Heartburn
• Shortness of breath with exertion

Women are less likely than men to believe they’re having a heart attack and more likely to delay seeking emergency treatment. Women also tend to be about 10 years older than men when they have a heart attack. While women may have the classic symptom of chest pain when experiencing a heart attack, they are also more likely to present with atypical symptoms.

Congenital heart defects
Congenital heart defects are heart problems that develop before birth. They can occur in the heart’s chambers, valves or blood vessels. Advances in surgery and medication mean that more and more children born with heart defects are surviving. In addition, minor congenital heart defects that don’t cause symptoms may not be diagnosed until a person is an adult or reaches middle age.

Heart failure
Heart failure develops when the heart doesn’t function properly. The names “heart failure” and “congestive heart failure (CHF)” don’t mean that the heart has actually “failed” or stopped but mean one or more chambers of the heart “fail” to keep up with the volume of blood flowing through them, with resultant back-up into the lungs and legs. Heart failure can be brought on by a variety of underlying diseases and health problems.

Peripheral Artery Disease
Peripheral arterial disease (PAD) is an increasingly recognized medical problem that results from narrowing of the arteries throughout the body. The arteries in the neck (carotid and vertebral arteries), arms (subclavian artery), kidneys and legs (femoral arteries) can all be affected by the process of cholesterol accumulation and vessel narrowing. Depending on the arteries that are narrowed, this process increases the risk of stroke, transient ischemic attacks, arm pains, chest pains, erectile dysfunction and leg pain/claudication symptoms.

In addition, patients can present with very-difficult-to-treat high blood pressure despite many medications which could be a sign of arterial narrowing in the kidney arteries.

One of the most common presentations for PAD is pain in the legs, especially in the calves, with walking. This is otherwise known as claudication and results from narrowing of the arterial vessels in the legs. This process can lead to eventual severe narrowing and lack of blood supply to the distal legs and feet and lead to non-healing ulcers and wounds. This is called critical limb ischemia. This is the number one cause of amputations and should be diagnosed and treated promptly.

Non-Invasive Tests

Electrocardiogram
An electrocardiogram (EKG or ECG) is a graphic measure of the electrical activity in your heart. There are specific patterns on the EKG that the physician looks for to determine whether there are abnormalities such as atrial fibrillation (an abnormal rhythm), new or old heart attack, etc.
During the test, you will lie on an exam table while an electrocardiograph machine records the information. You will be attached to the electrocardiograph by stickers on your chest that are connected to wires leading to the machine. The test takes less than 5 minutes.

Echocardiogram
An echocardiogram (“echo”) is an ultrasound of the heart. A small probe like a microphone, called a transducer, is placed on the chest in various places. The ultrasound waves sent by the transducer bounce off the various parts of the heart. A computer in the machine determines the time it takes for the sound wave to return to the transducer and generates a picture with the data.

During the test, you will lie on your back or left side on a stretcher for about 45 minutes while the pictures are being recorded. The echocardiographer will review the pictures before sending you home to be sure all the necessary information has been obtained.

Stress EKG or echocardiogram
Stress tests are performed to see how the heart performs under physical stress. The heart can be stressed with exercise on a treadmill or in a few instances, a bicycle. If a person cannot exercise on a treadmill or bicycle, medications can be used to cause the heart rate to increase, simulating normal reactions of the heart to exercise. During the stress test, you will wear EKG leads and wires while exercising so that the electrical signals of your heart can be recorded at the same time. Your blood pressure is monitored throughout the test. The stress test can be performed together with the echocardiogram, described above.

Nuclear Stress test

Nuclear stress tests have two components to them: a treadmill (or chemical) stress test and scanning of the heart after injection of a radionuclide material. The material has been used in this manner safely for many years to determine the amount of blood the heart muscle is getting under various conditions (rest and stress). The scanning is done with a nuclear camera.

Carotid ultrasound
Carotid ultrasound is done to evaluate your risk of stroke. The sonographer presses the transducer gently against the sides of your neck, which sends images of your arteries to a computer screen for the technician to see. The technician monitors your blood flow through the carotid arteries on both sides of your neck to check for stenosis. During the exam, you lie on your back on an examination table and a small amount of warm gel is applied to your skin. The test usually takes about 15- 30 minutes.

Abdominal ultrasound
Your doctor may also want you to have an abdominal ultrasound to screen for potential abdominal aortic aneurysm. The sonographer presses the transducer against your skin over your abdomen, moving from one area to another. The transducer sends images to a computer screen that the technician monitors. The technician monitors blood flow through your abdominal aorta to check for an aneurysm. During the exam, you lie on your back on an examination table and a small amount of warm gel is applied to your abdomen. The test usually takes form 20 minutes to an hour.

Holter Monitor
A Holter monitor is a small portable machine that you wear for 24-48 hours, it enables continuous recording of your EKG as you go about your daily activities. You will be asked to keep a diary log of your activities and symptoms. This monitor can detect arrhythmias that might not show up on a resting EKG which only records for a few seconds.

Event Recorder
An event recorder (loop recorder) is a small portable transtelephonic monitor that may be worn for several weeks. This type of recorder is good for patients whose symptoms are infrequent. The monitor ‘loops’ a 2-5 minute recording into its memory which is continually overwritten, when you experience symptoms you press the record button on the monitor which stores a correlating strip of EKG. The recordings are telephoned through to a 24 hour monitoring station and faxed directly to the requesting physician.

Invasive Tests

Cardiac catheterization and coronary angiography
Cardiac catheterization is a common procedure that can help your doctor diagnose a heart problem. In some cases, catheterization can be used to treat heart disease as well, by opening blocked arteries with balloon angioplasty and stent placement.

A cardiac catheterization can show:
• If the blood vessels in your heart have narrowed
• If your heart is pumping normally and blood is flowing correctly
• If the valves in your heart are functioning normally
• If you were born with any heart abnormalities
• If the pressures in the heart and lung are normal or abnormal; and if abnormal, to further
  assess what the etiology of the problem might be

The cardiologist inserts a long flexible tube called a catheter into a blood vessel (either thru the wrist artery (radial artery) or the groin artery (femoral artery) and gently guides it towards your heart under X-ray guidance. Once the catheter is in place, x-rays and other tests are done to help him evaluate whether your coronary arteries are blocked and how well your heart is working. At times, it might also be necessary to insert a small catheter into a vein to allow measurement of specific pressures in the heart and the lung. This procedure can be done either thru a neck vein, arm vein or femoral (groin) vein.

Electrophysiology study
An Electrophysiology study (EP) is a recording of the electrical activity of the heart. This test is used to help the doctor find out the cause of the patient’s rhythm disturbance (arrhythmia) and the best treatment. During the test, the doctor may safely reproduce the arrhythmia, and then give the medications to see which one controls it best.

An EP study is performed in the Electrophysiology Laboratory of a hospital, where the patient is placed on an x-ray table. As with a cardiac catheterization, the doctor inserts a long, flexible tube, an electrode catheter, into a blood vessel (usually the femoral vein, in the patient’s groin).

There are potentially three parts to the EP study:

1. Recording the heart’s electrical signals to assess electrical function;
2. Pacing the heart to bring on certain abnormal rhythms for observation under controlled conditions.
3. In some cases, an ablation procedure is performed at the same time, to destroy abnormal tissue which may be causing the patient’s arrhythmia.