To determine the presence of significant coronary artery disease (blockages in the arteries supplying the heart itself), stress testing is routinely performed. Electrodes are applied to the chest wall, and EKG leads are connected. The patient is then instructed to walk on a treadmill using a standardized protocol. If the patient has a significant blockage inside one or more arteries, he or she may experience chest discomfort. There may also be a change in the EKG during the test. Besides determining the presence or absence of coronary artery disease, stress testing is also used to assess a patient’s exercise capacity and to evaluate for exercise-induced arrhythmia.
In addition to exercise stress testing, nuclear stress testing can be used to evaluate a patient for the presence of coronary artery disease. Generally, nuclear stress testing is more accurate than regular exercise stress testing. In addition to walking on a treadmill, isotopes such as thallium, Cardiolite or Myoview are given to the patient intravenously. These agents are taken up by the heart muscle through its own dedicated arteries, enabling imaging of blood supply to the heart tissue. After the isotope is given, a blood-flow picture of the heart is obtained before the heart is stressed. Another isotope is injected while the heart is stressed and a second blood-flow picture is obtained. If there is a significant blockage in an artery, the territory of heart muscle supplied by that vessel will show reduced uptake of the isotope. This difference in blood flow allows the cardiologist to determine the presence and severity of coronary artery disease.
For patients who are unable to exercise, a chemical stress test is performed. Agents such as adenosine, persantine, and dobutamine are used to chemically stress the heart. Patients are instructed not to eat or drink anything for several hours prior to the test. They are also instructed to avoid caffeine products for at least 24 hours prior to the test to improve accuracy. Similar to exercise nuclear stress testing, isotopes are injected and images are obtained at rest and with stress. Comparisons are made between the two sets of images to determine to presence and degree of coronary artery disease. These tests are very safe and serious complications are very rare. Pregnant patients cannot receive nuclear stress testing. The entire procedure takes 2 to 3 hours to allow for adequate heart imaging.
An echocardiogram is an ultrasound examination of the heart. Using an ultrasound source on the chest, a real-time image of the heart is obtained. In addition, Doppler echo and a single-dimension image known as M-mode echo can help obtain further information about the heart. Electrodes are applied for EKG recording and gel is applied on the chest to improve image quality. An echocardiographer will obtain images of the heart and store them for the cardiologist to review. The test typically takes about 30 minutes and there is no preparation involved. An echocardiogram is a very powerful diagnostic tool and can give very accurate information regarding heart size, structure, and function.
This is another testing modality used to diagnose the presence and extent of coronary artery disease using ultrasound technology. The patient is stressed either physically with exercise or chemically with dobutamine. Ultrasound pictures of the heart are obtained prior to and at the peak of the exercise. Patients with significant coronary artery disease show worsening of the heart’s ability to pump with exercise. Often, part of the heart wall reveals abnormal contraction compared to the rest of the heart wall. This test is useful for patients who cannot tolerate a nuclear stress test.
Cardiac monitoring devices are available to evaluate patients for hidden heart rhythm disturbances which may manifest as palpitations, a “pounding” or “racing” sensation, dizziness, fainting, shortness of breath, fatigue, or with no symptoms at all. These devices consist of a small “box” unit which is linked to several electrode leads attached to the chest. They are small, worn underneath one’s clothing, and can be carried or attached to a belt or waistband. A Holter Monitor is worn by the patient for 24 to 48 hours, and allows continuous monitoring of the patient’s heart rhythm. It is useful for detecting unsuspected abnormal heart rhythms in patients lacking symptoms, or in patients who have symptoms frequently throughout the day. An event recorder is worn for 30 days, but only records when it is triggered by the patient (i.e. a button is pressed to trigger the device to record). It is most useful in identifying the cause of symptoms in patients that only experience them infrequently.
Vascular ultrasonography refers to a variety of diagnostic ultrasound examinations performed on blood vessels more distant from the heart. These include carotid duplex ultrasonography, peripheral arterial duplex ultrasonography, and lower extremity venous duplex ultrasonography. Vascular ultrasound is a noninvasive way to detect and assess the severity of circulatory problems. Ultrasonography of the carotid arteries is used locate areas of obstructed blood flow in the major arteries leading to the brain, which could eventually lead to a stroke. Arterial duplex ultrasound is used to assess blood flow in the legs, especially in patients with known circulatory problems or with prior vascular surgery. Venous duplex ultrasonography is used in patients with pain and swelling in the lower limb to exclude the presence of a venous blood clot.
This is a simple test used to screen for the presence of peripheral arterial disease (PAD) or impaired arterial circulation. This test uses four blood pressure cuffs to compare the pressures in the arms and legs. A lower blood pressure in either leg compared to those in the arms may suggest the presence of PAD. Patients with PAD often have pain, burning, or cramping in the calf, thighs, or buttocks that limits their ability to walk or exercise. The presence of PAD is an important predictor of an increased risk for heart attack and stroke. Therefore, the ABI test is a fast, noninvasive way to screen for cardiovascular disease, especially in patients who experience leg pain during increased activity.
Patients with implanted permanent pacemakers or defibrillators require a test of their device at least twice a year to assess battery life, to ensure that the device is functioning properly, and to make any appropriate adjustments to the settings. Newer devices also have heart monitoring capabilities, and the information recorded can be retrieved during the interrogation. Device testing and analysis is simple, and involves placing an interrogator “wand” over the site of the implanted pacemaker or defibrillator. A full computerized report is then obtained, and any necessary adjustments are made under the supervision of the cardiologist.
Coumadin (generically called warfarin) is a blood thinner that is used for the treatment and prevention of blood clots. Monitoring at regular intervals is required to ensure that the blood is kept adequately thin for effective treatment, but does not become too thin. A blood test, reported as an INR (International Normalized Ratio), is obtained in our office through a simple fingerstick. The Coumadin clinic is staffed by technicians trained in Coumadin management, and results are available almost immediately. Depending on the INR levels, the Coumadin dose may require adjustment. INR levels should be checked every 1-4 weeks once a therapeutic dose is achieved.
Occasionally a very detailed picture of the heart is difficult to obtain using a standard echocardiogram study. This occurs because ultrasound is often scattered through bone, muscle, and lung tissue. TEE is a test in which an ultrasound probe is gently inserted into a patient’s esophagus and stomach to obtain a detailed picture of the heart from behind it. Because the ultrasound beam doesn’t have to pass through the chest wall, extremely accurate details of the heart structures are seen. TEE is especially useful for locating heart valve infections and for identifying the presence of a clot inside the chambers of the heart.
Patients receiving a transesophageal echocardiogram are instructed not to eat or drink anything for eight hours prior to the test. Prior to insertion of the ultrasound probe, a numbing spray is given to the back of the throat to minimize the gag reflex. Then mild to moderate sedation with intravenous medications is given for patient comfort. The test generally takes about 30 minutes. Although this procedure is very safe, there is a small risk of minor throat irritation, breathing difficulties, and heart rate slowing. Perforation or tear of the esophagus is extremely rare.
A tilt table test is used to diagnose vasovagal or neurally-mediated syncope (passing out or loss of consciousness). There are many causes of syncope, and identifying neurally-mediated syncope is important, as there are specific treatments available for this type. The patient is kept in a standing position for between 1/2 and 1 whole hour. During this time, the heart rate and blood pressure are monitored. Patients with neurally-mediated syncope often display exaggerated heart rate slowing and blood pressure decrease during the test. To prepare for the test, patients should withhold medications and not eat or drink after midnight on the day of the exam.
This is an invasive test, but it is considered the gold standard to evaluate for coronary artery disease. After being brought to the catheterization room, the patient is given a mild sedative for comfort. Then, the groin (or occasionally the arm) is prepared for the procedure in a sterile manner. The catheterization site is then numbed using a local anesthetic introduced with a small needle syringe containing lidocaine. After local anesthesia, a plastic sheath is inserted into the artery.
Through this sheath, a long plastic tube, the size of a spaghetti noodle is inserted. Using special X-ray equipment, the tube is directed through the artery and into selected areas in the heart and the arteries supplying it with blood. Dye is injected to determine the location and severity of blockages in the coronary arteries. If a severe blockage is noted, recommendations for corrective procedures such as angioplasty (opening the blockage using a balloon), stent placement (inserting a metal tube to prop open the site of blockage), or bypass surgery are made. In addition, cardiac catheterization allows measurement of heart function, and of the pressures inside the heart chambers and lungs. This is useful to determine the presence of congestive heart failure, valvular heart disease, and lung disease.
To prepare for the procedure, the patient is instructed not to not eat or drink anything after midnight on the day of the procedure. Occasionally, IV fluid is given for hydration. For patients with kidney problems, a special medication is given the day before to protect kidney function. Patients are instructed to withhold certain medications both before and after the catheterization.
The procedure generally takes about an hour. After completion, the tube and sheath are removed. A plugging device may be used to reduce bed rest duration after the catheterization. Routine bed rest for a few hours is required to minimize bleeding and to avoid injury to the catheterization site. Because of the sedation, the patient cannot drive until the next day. Mild discomfort and discoloration may be noted in the catheterization site after the procedure.
Peripheral angiography is similar to cardiac catheterization in that similar X-ray equipment and dye are used. However, this test is used to determine the presence of blockages in arteries in other parts of the body, such as in the neck, legs or aorta. If a significant blockage in the peripheral arteries is found, one can consider angioplasty (opening the blockage using a balloon), stenting (inserting a metal tube in the site of blockage) or bypass surgery.
Occasionally, patients may become very sick and require treatment in an intensive care unit. They may have low urine output and low blood pressure, and have trouble with oxygenation. At times, it becomes difficult to assess their volume status (whether they have too much or too little fluid in the body). Invasive monitoring with a Swan-Ganz Catheter may be useful for obtaining further information. Typically, a sheath is inserted in a patient’s central vein. Using this sheath, a long, balloon tipped catheter is inserted and “floated” through the heart to allow accurate pressure measurements in the heart. Complications may include irregular heart rhythms, bleeding and infection.
Patients who have a condition called atrial flutter (or atrial fibrillation), characterized by an irregular heartbeat, can undergo a procedure called a cardioversion to restore their normal cardiac rhythm. Patients who have been on adequate doses of a blood thinner (Coumadin/warfarin) for at least 3-4 weeks can safely undergo this procedure, which consists of moderate sedation under the supervision of a cardiologist and/or anesthesiologist, after which a brief electrical shock is delivered to the heart through electrical pads placed on the chest. This process can “jolt” the heart back to a normal rhythm. Patients are observed for a brief period and usually go home on the same day of the procedure.
Patients may experience dizziness, shortness of breath, weakness, or syncope (passing out) due to either a very slow heart rate or a heart block ( an inability of the electrical system of the heart to conduct properly). For patients with these symptoms, insertion of a pacemaker is advised. A pacemaker consists of a battery pack and electrode wires. The battery pack is approximately the size of a silver dollar and is placed under the skin on the left upper chest.
Patients are instructed not to eat or drink after midnight on the day of the procedure. During the procedure, patients are given intravenous sedation for comfort. After adequate local anesthesia, a small incision is made in the left upper chest. Through the incision, the subclavian vein (a large vein that travels to heart) is located. Using X-ray guidance, the tip of a wire is inserted and attached to the heart muscle, while the other end is attached to the battery pack. Once the wires are attached, the incision is closed. The risks of the procedure are generally low under experienced hands. Risks usually include problems with sedation, bleeding, and infection. Very rarely, the lung may be punctured, requiring either close observation or re-expansion with a chest tube. Patients are kept overnight for observation.
Patients with mainly ventricular arrhythmias can be good candidates for stabilization via ICD, a permanent safeguard against sudden arrhythmia. Similar to pacemakers, ICDs are implanted beneath the skin, and may require electrodes to be wired through the subclavian vein to the heart tissue. After adequate sedation, local anesthesia is administered, and a small pocket is made under the skin to house the device. Then, the necessary electrical connections to the heart are established. ICDs have clear life-saving capability, and most patients with an ICD experience increased quality of life with minimal restrictions on activity.
An Implantable Loop Recorder (ILR) is a cardiac monitoring device placed under the skin that allows the activity of the heart to be recorded before, during, and after abnormal heart rhythm. Electrical activity from the heart can be continuously recorded in a loop, but is replaced with later recordings unless triggered for storage by the patient or by heart activity outside of parameters determined by a physician. Patients may be asked to press a button when they feel symptoms of arrhythmia, such as palpitations, a “racing” heart, dizziness, fatigue, or shortness of breath. This triggers the device to save the recording for the time period around the event, which can be later retrieved.
These monitors are similar to Holter monitors and event recorders, but their placement within the body makes them more appropriate for longer-term and continuous care. After adequate sedation, a local anesthetic is applied and a small incision made below the patient’s left collarbone. An area of skin is teased up to form a pocket holding the ILR, and electrical leads are placed to monitor the heart. Implantation is generally an outpatient procedure with minimal restrictions on activity. Patients will be instructed on how to use the recorder by their physician, and will schedule appointments to have its data retrieved for interpretation.
In patients with poorly controlled heart disease, percutaneous coronary intervention (PCI) provides a less invasive alternative to bypass surgery. It allows an interventional cardiologist or radiologist to treat coronary artery disease by directly opening narrowed or obstructed arteries via a long tube (catheter) inserted into the arterial system. After being brought to the catheterization room, the patient is given a mild sedative for comfort. The site of insertion (the groin or occasionally arm) is prepared in a sterile manner, and then numbed using a local anesthetic. An incision is made, and a plastic sheath is inserted into the artery.
A special catheter is introduced through this sheath and directed to the heart using X-ray equipment. Dye may be injected to confirm the severity of blockages in the coronary arteries. Various corrective procedures may then be performed, most often angioplasty (opening the blockage using a balloon) and stent placement (inserting a metal tube to prop open the site of blockage.) PCI immediately increases blood flow to heart tissue, and is of greatest benefit to patients with unstable heart disease. Precautions similar to those for cardiac catheterization are taken, and the risk of complications is similarly low.
This detailed examination of the electrical signaling within the heart allows for the precise stimulation of heart regions, as well as offering intervention to deactivate faulty electrical conduction pathways. EPS is recommended for those patients with faulty cardiac electrical conduction that does not respond to medication, especially that leading to ventricular fibrillation. Complete evaluation by EPS with ablation may take several hours, and patients are directed to refrain from eating and drinking beforehand, or driving afterwards.
Similar in setup to other minimally invasive cardiac catheterization procedures, patients are sedated and anesthetized as a flexible tube is inserted through a sterilized area in the groin or wrist. Then, the catheter is directed through the veins to the heart, where the electrophysiologist will use X-rays to observe as he or she uses large magnets to guide electrodes at the tip of the device. Electrical activity can be sensitively measured in all chambers of the heart, current can be applied to probe function, and suspected arrhythmia can be localized and confirmed with proarrhythmic drugs and/or electrical stress.
Once a dysfunctional group of cells is identified, a separate tool in the catheter can be employed to ablate (destroy) only the misfiring tissue using powerfully directed radio waves. Ablation by this method has an extremely high success rate in treating most arrhythmias. Patients may be asked to remain overnight for rest and observation, with some activity generally permitted within 24 hours, and more vigorous activity allowed under the advice of a physician.