Heart Disease UK

By DrRich

Magnetic Resonance Imaging (MRI) has long been useful for diagnosing problems of the brain, spine and joints. Over the past decade, MRI has proven useful in diagnosing certain uncommon cardiovascular problems such as aortic dissection, cardiac tumors, and congenital heart disease. And MRI has proven a valuable research tool for studying more common cardiac disorders such as ischemia and cardiomyopathy. Until recently, however, it has been impractical to use MRI where it would be the most useful – in the routine evaluation and management of patients with coronary artery disease.
All that appears about to change. New techniques are becoming available that promise to deliver the holy grail of cardiology– a means to non-invasively image the coronary arteries – and to do it with far more precision than is achieved by today’s gold standard, coronary angiography.
In December, 2001, researchers at Harvard reported in the New England Journal of Medicine that they were able to use MRI scanning of the coronary arteries to detect disease in the major branches of the coronary arteries. They reported an overall accuracy of 72% with the MRI technique, and a much higher accuracy for disease of the left main coronary artery (which, while relatively uncommon, is the most dangerous place for a person to have coronary artery disease.)

What is MRI?
MRI is an imaging technique that takes advantage of the property of certain atomic nuclei (in this case, the single proton that forms the nucleus of a hydrogen atom) to vibrate – or “resonate” – when exposed to bursts of magnetic energy. When the hydrogen nuclei resonate in response to changes in a magnetic field, they emit radiofrequency energy. The MRI machine detects this emitted energy, and converts it to an image.
The MRI offers a potential means of detecting areas of cardiac tissue that have poor blood flow (as in coronary artery disease) or that has been damaged (as in a heart attack).
However, there are many technical problems in imaging moving structures like the heart with MRI. Movement of the heart during scanning significantly distorts the image (just as taking a photo of a moving object causes a blurring of the picture), and when the structures you are trying to see are small the movement problem becomes extremely difficult to overcome. Technology is progressing rapidly, however, and commercial MRI machines that can produce high-quality heart images are already being used in many research institutions.

How is cardiac MRI useful today?
While MRI machines abound in the United States, cardiac MRI, because of its complexity, has largely been limited to university hospitals where there is a strong research interest. Accordingly, much of the work with cardiac MRI has been done in the research setting.
Because of the difficulties in producing detailed MRI heart scans, only a few uses of cardiac MRI have become more-or-less routine. MRI has proven very useful in evaluating patients with aortic dissection prior to surgery. The detailed images offered by MRI tell the surgeon precisely where the “tear” in the wall of the aorta begins, and the full extent of the dissection. MRI can also locate and characterize the rare cardiac tumor. And in children with complex congenital heart disease, MRI can help to identify and “sort out” the various anomalies, and to plan potential surgical approaches to treatment.
While such applications of MRI are very helpful, these clinical situations are relatively rare. So cardiac MRI has yet to become a commonly used tool in clinical medicine.

What are some of the potential uses of cardiac MRI?
Once certain limitations are overcome – and that day seems to be rapidly approaching – the uses of cardiac MRI will explode.
MRI has the potential to diagnose heart attacks in patients presenting with chest pain. Not infrequently, a patient coming to the emergency room with chest pain will not have the typical ECG changes seen with myocardial infarctions, and the doctors end up waiting for an hour or two for the results of cardiac enzyme tests.
MRI can help distinguish between “stable” atherosclerotic plaques and “vulnerable” plaques. Vulnerable plaques are those that are prone to rupture, thus suddenly occluding a coronary artery and causing a myocardial infarction. If vulnerable plaques can be identified, those particular plaques can be targeted for intervention (angioplasty, stent, or bypass), while leaving the stable plaques alone.
MRI has already proven useful in the research setting for identifying restenosis after angioplasty. MRI might thus prove an accurate, noninvasive means of following patients after angioplasty.
MRI may replace the x-ray tube in both diagnostic and therapeutic situations. Research is already being done in animals using MRI to image the coronary arteries – instead of using fluoroscopy – for angioplasty procedures.

What about this week's report from Harvard on using MRI for diagnosing coronary artery disease?
Report in the New England Journal of Medicine constitutes another step forward, but MRI is still quite a ways from being ready to replace cardiac catheterization for most patients. While an accuracy of 72% is encouraging, it is certainly nowhere near the nearly 100% accuracy achieved with cardiac catheterization and coronary angiography. So, aside from the other disadvantages listed below, today the MRI is not accurate enough to substitute for coronary angiography when you really need to know the status of the coronary arteries. Indeed, while progress is ongoing, the MRI today is scarcely better in overall accuracy than the less inconvenient noninvasive tests that are used every day in cardiology.

Summary
MRI technology holds tremendous promise in the evaluation and treatment of heart disease. It is clearly technically feasible for MRI to replace – and significantly improve on – many of the sophisticated imaging techniques that are now routinely performed in cardiology. The potential for MRI to accurately diagnose and direct the treatment of coronary artery disease before it becomes clinically apparent is probably the most exciting prospect. Before this can happen, however, the amazing technology now being developed needs to be made accurate enough and inexpensive enough to achieve broad usage.

From Richard N. Fogoros, M.D.
A common congenital heart disorder
Hypertrophic cardiomyopathy (HCM), originally felt to be rare, is now known as a common congenital heart disease that causes several varieties of heart problems – not the least of which is sudden death.

What is HCM and what causes it?
HCM is a form of heart disease in which the muscular walls of the ventricles become abnormally thickened. The thickening of the heart muscle causes the muscle itself to function abnormally. The thickening can also cause the ventricles to become distorted, which can interfere with the function of the aortic valve and the mitral valve.
HCM is caused by a genetic abnormality that produces a striking disorder in the growth of the heart muscle fibers.
However, in almost half the patients with HCM, the genetic problem is not inherited at all, but occurs as a spontaneous mutation – in which case parents and siblings of the patient will not be at risk for this condition (but children of the patient can be.)

What problems does HCM cause?
There are four kinds of cardiac problems caused by HCM:
1) HCM can cause diastolic dysfunction. "Diastolic dysfunction" refers to the fact that thickened ventricles become stiff, making it more difficult for the ventricles to fill with blood. This stiffness causes the blood to "back up" into the lungs, causing shortness of breath – usually with exertion. The diastolic dysfunction also makes it more difficult for patients with HCM to tolerate arrhythmias, especially atrial fibrillation.
2) HCM can cause systolic dysfunction. "Systolic dysfunction" means that the heart's pumping action is not normal - that is, when the heart beats, an unsufficient volume of blood is ejected. In HCM, systolic dysfunction is usually caused by abnormal functioning of the mitral or aortic valves, which, in turn, is caused by distortion of the ventricles resulting from the abnormal thickening of muscle.
3) HCM can cause dilated cardiomyopathy. This condition leads to heart attack, and is caused by an eventual “burning out” of the thickened heart muscle. Dilated cardiomyopathy occurs late in the course of the disease.
4) Finally, HCM can cause sudden death. The sudden death in HCM is usually due to ventricular tachycardia or ventricular fibrillation. While many of these sudden deaths occur during vigorous exertion, it can also occur during minimal exertion or at rest, with no warning whatsoever. The risk of sudden death has been estimated being as high as 5% per year in patients in their teens and 20s, though it drops off somewhat after that.

How is HCM diagnosed?
In general, the echocardiogram is the best method of diagnosing HCM. The echocardiogram allows accurate measurement of the thickness of the ventricular walls, and can detect abnormal heart valve function as well. The electrocardiogram (ECG) also can give important clues as to the presence of HCM.
Both an ECG and echocardiogram should be performed in close relatives of a patient diagnosed with HCM, and an echocardiogram should be performed in any person in whom the ECG or the physical examination suggests ventricular hypertrophy.

How is HCM treated?
HCM cannot be cured, but it can be managed. Beta blockers and calcium blockers can help reduce the "stiffness" in the thickened heart muscle. In some patients - especially those who have significant heart valve dysfunction - surgery to remove portions of the thickened heart muscle is necessary. Atrial fibrillation, if it occurs, often causes severe symptoms and needs to be managed more aggressively in patients with HCM than in the general population.

How can sudden death be prevented?
Sudden death in HCM is often seen in younger patients – often before symptoms have occurred, or even before a diagnosis has been made. While sudden death is always a devastating problem, it is particularly so when it occurs in young people.
Many methods have been tried for reducing the risk of sudden death in patients with HCM - including avoiding exercise, using beta blockers and calcium blockers, and using antiarrhythmic drugs - these methods unfortunately met with mixed results. In recent years it has become apparent that in patients whose risk of sudden death appears high, an implantable defibrillator should be used. The implantable defibrillator is a pacemaker-like device that is implanted under the skin, monitors the heart rhythm continuously, and automatically delivers a shock to the heart to restore a normal rhythm should a dangerous ventricular arrhythmia occur. While it sometimes seems a drastic step, it is much less drastic than allowing a young individual to die suddenly.

By DrRich
EECP may help in heart failure
Enhanced External Counterpulsation (EECP) is a procedure that has proven beneficial in patients with angina. Some have long speculated that the cardiovascular effects induced by EECP might also be useful for patients with heart attack.

What is EECP?
EECP is a mechanical procedure in which long inflatable cuffs (like blood pressure cuffs) are wrapped around both of the patient’s legs. While the patient lies on a bed, the leg cuffs are inflated and deflated with each heartbeat. This is accomplished by means of a computer, which triggers off the patient’s ECG so that the cuffs deflate just as each heartbeat begins, and inflate just as each heartbeat ends. When the cuffs inflate they do so in a sequential fashion, so that the blood in the legs is “milked” upwards, toward the heart.

EECP has two potentially beneficial actions on the heart. First, the milking action of the leg cuffs increases the blood flow to the coronary arteries. (The coronary arteries, unlike other arteries in the body, receive their blood flow after each heartbeat instead of during each heartbeat. EECP, effectively, “pumps” blood into the coronary arteries.) Second, by its deflating action just as the heart begins to beat, EECP creates something like a sudden vacuum in the arteries, which reduces the work of the heart muscle in pumping blood into the arteries.

EECP in heart failure
In a study, 26 patients with stable congestive heart attack were enrolled to receive a standard, 35 session course of EECP. 19 patients completed the EECP sessions and were followed for 6 months afterward. These patients showed, on average, a significant improvement in their functional capacity and quality of life. The authors point out, as well, that the EECP was well-tolerated in these patients.
Since there were no control subjects in this small study, no firm conclusions can be drawn about how useful EECP might be in treating heart failure. But the study was impressive enough to launch a larger, randomized clinical trial that should provide more definitive data on how well EECP might benefit patients with heart failure. The PEECH trial has already begun.
Despite the fact that the potential benefits of EECP in heart failure are still being evaluated, the FDA was sufficiently convinced of these benefits that it cleared the makers of the EECP system (Vasomedical) to begin promoting EECP for heart failure.
Most cardiologists have not embraced the use of EECP for heart disease, quite justifiably citing the need for larger clinical trials. However, since cardiologists don't like EECP even when it is of proven benefit, patients with heart failure who are interested in this treatment option should watch for results of the PEECH trial, and if they prove positive, should take the initiative in bringing up the option of EECP to their doctors.

From Richard N. Fogoros, M.D.
Causes, symptoms, diagnosis, and prognosis

What is cardiomyopathy? What is heart failure?
Cardiomyopathy is disease of the heart muscle.
In most cases, cardiomyopathy causes the heart muscle to become weak. Various medical disorders cause various types of cardiomyopathy, but all types of cardiomyopathy ultimately do the same thing – they reduce the efficient functioning of the heart muscle, and diminish the ability of the heart to meet the needs of the body. When the heart can no longer pump enough blood to meet the needs of the body, heart failure is said to be present.

What are the types of cardiomyopathy?
There are three major types of cardiomyopathy – dilated cardiomyopathy, hypertrophic cardiomyopathy, and restrictive cardiomyopathy. The vast majority of patients who develop cardiomyopathy have the dilated form. So, after briefly describing hypertrophic and restrictive cardiomyopathies, we will concentrate on dilated cardiomyopathy for the remainder of this article.
Hypertrophic cardiomyopathy is a genetic disorder that causes a chaotic growth of heart muscle cells within the ventricles. The disordered, thickened heart muscle can lead to problems pumping sufficient blood to the body’s organs, and can cause potentially fatal cardiac arrhythmias. Restrictive cardiomyopathy is a very rare condition in which the heart muscle is infiltrated, and made stiff, by abnormal cells, protein, or scar tissue. The stiffening of the ventricles restricts the return of blood to the heart, causing the blood to “dam up” into the body’s organs. The most common cause of restrictive cardiomyopathy is amyloidosis, a disease in which protein-like substance is deposited within the body’s tissues. Other causes include sarcoidosis and hemochromatosis.
In dilated cardiomyopathy, previously normal heart muscle becomes damaged, leading to a generalized weakening of the walls of the cardiac chambers. To compensate for the weakening of their muscular walls, the cardiac chambers dilate. The weakening and the dilation of the heart muscle eventually lead to heart failure.
What causes dilated cardiomyopathy?
Because almost anything that damages cardiac muscle can lead to dilated cardiomyopathy, there are many causes.
The most common cause of cardiomyopathy in developed nations is coronary artery disease. Heart attacks cause death of heart muscle by obstruction of a coronary artery. While the damage is localized to the region of muscle supplied by that artery, within a few months the entire left ventricle dilates to compensate for the damage. With a small heart disease, the amount of ventricular dilation is minimal. But with a large heart attack or a series of smaller heart attacks, dilated cardiomyopathy becomes extensive, and heart failure ensues.
Another common cause of dilated cardiomyopathy is inflammation of the heart muscle, a condition called myocarditis. Myocarditis is most often caused by viral infections, but can also be caused by bacterial infections and by non-infectious causes such as lupus and other inflammatory diseases.
Alcohol is another cause of cardiomyopathy. In some patients (probably determined by genetic predisposition), alcohol acts as a powerful toxin to heart muscle, directly damaging cardiac cells. Alcoholic cardiomyopathy can be seen after as few of five years of excessive alcohol intake.

From Richard N. Fogoros, M.D.
Symptoms, diagnosis, and prognosis

Causes of dilated cardiomyopathy
Valvular heart disease, especially aortic regurgitation and mitral regurgitation, cause dilated cardiomyopathy. Indeed, the gradual enlargement of the cardiac chambers is an important sign that the time may be right for valve replacement or repair.
Nutritional abnormalities – especially a deficiency in vitamin B1 – can cause cardiomyopathy. Cardiomyopathy sometimes develops in women within a month of delivering a baby. This so-called peripartum cardiomyopathy is the result of a myocarditis that occurs for unknown reasons, associated with childbirth.. There are also genetic forms of dilated cardiomyopathy.
This is why some families are clearly affected by an extremely high incidence of dilated cardiomyopathy.
Cardiac “overwork” is another cause of dilated cardiomyopathy. Any condition that causes the heart muscle to work at high loads for prolonged periods of time (weeks or months) can eventually cause cardiac dilation and weakening of the heart muscle. Such conditions include prolonged severe anemia, abnormal sustained tachycardias, chronic hyperthyroidism, and the overwork produced by leaky heart valves.

What are the symptoms of dilated cardiomyopathy?
The symptoms of cardiomyopathy are those of heart disease. These include shortness of breath and/or fatigue with exertion or when lying down, waking up at night gasping for air, and swelling in the lower legs.

How is cardiomyopathy diagnosed?
Diagnosing dilated cardiomyopathy depends on demonstrating enlargement of the cardiac chambers, especially the ventricular chambers. Such enlargement can be seen on chest X-ray, but can be more accurately assessed using an echocardiogram or a MUGA scan.
Once dilated cardiomyopathy is found, every effort should be made to identify a potentially reversible cause. Coronary artery disease and valvular heart disease need to be ruled out. Anemia, abnormal tachycardias, nutritional deficiencies, alcoholism, and thyroid disease also need to be ruled out. Sometimes, a cardiac biopsy is performed to rule out active myocarditis.

What are the clinical pattern and prognosis of dilated cardiomyopathy?
Since it is generally causes no symptoms until actual heart failure sets in, by the time cardiomyopathy is diagnosed, heart disease is usually already fairly advanced. Classically the clinical pattern of a patient with dilated cardiomyopathy is characterized by episodes of severe heart failure that lead to hospitalization, followed by relatively long periods of “baseline” symptoms. During this baseline period, patients often have symptoms only with exertion. As time goes by, the episodes of severe coronary heart disease come more and more frequently, and the “baseline” periods are characterized by a gradually worsening level of symptoms. In the year or so prior to death, frequent hospitalizations are common, and it is usually apparent to both patient and doctor that a steady, unrelenting deterioration is under way.