Each year in the United States, thousands of adults and children are diagnosed with a disease of the heart called cardiomyopathy. This is a condition in which the heart muscle, called myocardium, becomes progressively weakened. Cardiomyopathies encompass a broad collection of heart diseases, with a multitude of causes and treatments.
Annually, the diagnosis of cardiomyopathy is made in roughly one in every 100,000 children younger than 18 years. While in the adult population, cardiomyopathy is the cause of death in 10,000 Americans each year, and is responsible for nearly 50,000 hospitalizations. Additionally, it is the leading indication for heart transplantation.
The presenting feature and underlying cause for cardiomyopathies vary somewhat, and are broadly classified into four groups including; dilated cardiomyopathy, hypertrophic cardiomyopathy, restrictive cardiomyopathy, and miscellaneous cardiomyopathy.
Dilated cardiomyopathy (DCM) is the most common cardiomyopathy. These patients have weakened heart muscle with impaired squeezing function, and the hearts are characteristically stretched and enlarged (dilated). They develop symptoms of fatigue, shortness of breath, inability to sleep flat, weight gain, and leg and abdomen swelling. The causes of DCM are prior heart attacks, viral infections, genetic disorders of the heart muscle, pregnancy related, alcohol and drug abuse, long standing hypertension and obstructive sleep apnea. However, the most common cause of all DCMs is never clearly determined. These DCMs are referred to as idiopathic DCMs.
The second type of cardiomyopathy is hypertrophic cardiomyopathy (HCM). HCM is a genetic disease of the heart muscle, in which the heart muscle enlarges in an unnatural fashion, called hypertrophy. These hypertrophied hearts become so enlarged that they become incapable of contracting appropriately. In a rare version of HCM, called hypertrophic obstructive cardiomyopathy, there is localized enlargement of the heart muscle that obstructs the heart#,s forward blood flow. This obstruction puts people at high risk of passing out and lethal heart arrhythmias.
The age of onset of HCM is usually adolescence and is a common cause of sudden death in young athletes. Interestingly, patients with HCM tend to have mild or no symptoms. They are either sporadically detected with routine screening, or present after sudden cardiac arrest. As patients with HCM age, some begin to show mild symptoms of their weakened heart muscle, including difficulty breathing, easy fatigue, racing heart beats, or passing out.
The prognosis of HCM is quite poor. Most succumb to a life threatening arrhythmia, stroke, or congestive heart failure. The young seem to be at highest risk of sudden cardiac death, while death due to stroke or heart failure is seen more commonly in middle to older aged patients. Overall, patients with HCM have a death rate of 12 percent over a seven-year period from the time of diagnosis.
A third type is restrictive cardiomyopathy (RCM). Unlike DCM and HCM, patients with RCM actually have normal sized hearts with normal squeezing function, yet the heart muscle is stiff and is unable to relax. These stiff hearts are unable to appropriately fill with blood and are therefore unable to pump sufficient blood to the body.
The causes of RCM include; radiation exposure, chemotherapy, genetic heart muscle diseases, and rarely sarcoidosis and amyloidosis. Unlike the other causes of cardiomyopathy, RCM tends to have an older age of onset, and a female preponderance. The symptoms of RCM are similar to those of other types of cardiomyopathy, including fatigue, weakness, difficulty breathing and weight gain. Unique to RCM is leg and abdominal swelling.
The prognosis of RCM is equally poor, with advanced age and signs of congestive heart failure being the mortality highest risks. The overall survival ten years from diagnosis is only 37 percent. Like other cardiomyopathies, the cause of death is usually heart failure, stroke or life-threatening arrhythmias.
The final group, miscellaneous cardiomyopathy, is a collection of quite rare and diverse conditions. These include long-standing fast heart rates (tachycardia-mediated cardiomyopathy) and ARVD in which the heart muscle develops lethal patches of fatty tissue deposits. Another very rare condition is Takotsubo's cardiomyopathy, in which a sudden emotionally traumatizing event leads to a localized region of muscle weakness. This condition is more commonly seen in Asian populations and has appropriately been termed “broken heart syndrome.”
The treatment of all cardiomyopathies is largely the same, being optimal medical therapy. The goal of medical therapy is to reduce the heart's overall work load. This is accomplished with several classes of medications including: heart rate medications (beat blockers, calcium channel blockers and digoxin), blood pressure medications (diuretics, ACE-inhibitors, ARBs), and medications that regulate blood volume (diuretics). In some patients, their weakened heart muscle significantly increases the risk of developing fatal blood clots. Therefore, many require long- term blood thinners.
In some instances, surgical procedures like implantation of a pacemaker may be necessary to regulate heart rate and optimize cardiac function. In patients with the obstructive version of HCM, surgical resection of the obstructive portion of the hypertrophied heart muscle may reduce the obstruction to forward blood flow and significantly improve symptoms. More recently, this surgical procedure has been replaced by a catheter based procedure in which concentrated ethanol is injected directly into this obstructive muscle. Soon after the injection, the muscle dies and significantly shrinks, ultimately correcting the obstruction.
Lastly, one of the most common causes of death in cardiomyopathy patients is life threatening arrhythmias. In addition to the above medications, the best therapy for these arrhythmias is an implantable cardiac defibrillator (ICD). These are permanent devices which can detect and shock a life threatening arrhythmia in less than 10 seconds.
In advanced cardiomyopathy, selected patients are referred for cardiac transplantation. The overall prognosis of patients with successful heart transplantation is markedly improved over those patients with medical therapy alone. The usual limitation is the long transplant list, most commonly due to a paucity of available donors.
Long-term care includes strict medical therapy and close follow-up with a cardiologist. Additionally, some cardiomyopathies are genetic, which therefore require screening of immediate family members. The follow-up diagnostic tests usually include EKG#s and sonograms of the heart (echocardiograms) to assess for significant changes.
Although cardiomyopathies are somewhat uncommon in the Unites States, they are critically important diseases with high long-term morbidity and mortality. When suspected, patients and their family members will need to work closely with their cardiologist to battle this disease.
Dr. David M. Donaldson is an Auburn native and currently a
cardiologist at Massachusetts
General Hospital in Boston
The presenting feature and underlying cause for cardiomyopathies vary somewhat, and are broadly classified into four groups including; dilated cardiomyopathy, hypertrophic cardiomyopathy, restrictive cardiomyopathy, and miscellaneous cardiomyopathy.
Dilated cardiomyopathy (DCM) is the most common cardiomyopathy. These patients have weakened heart muscle with impaired squeezing function, and the hearts are characteristically stretched and enlarged (dilated). They develop symptoms of fatigue, shortness of breath, inability to sleep flat, weight gain, and leg and abdomen swelling. The causes of DCM are prior heart attacks, viral infections, genetic disorders of the heart muscle, pregnancy related, alcohol and drug abuse, long standing hypertension and obstructive sleep apnea. However, the most common cause of all DCMs is never clearly determined. These DCMs are referred to as idiopathic DCMs.
The second type of cardiomyopathy is hypertrophic cardiomyopathy (HCM). HCM is a genetic disease of the heart muscle, in which the heart muscle enlarges in an unnatural fashion, called hypertrophy. These hypertrophied hearts become so enlarged that they become incapable of contracting appropriately. In a rare version of HCM, called hypertrophic obstructive cardiomyopathy, there is localized enlargement of the heart muscle that obstructs the heart#,s forward blood flow. This obstruction puts people at high risk of passing out and lethal heart arrhythmias.
The age of onset of HCM is usually adolescence and is a common cause of sudden death in young athletes. Interestingly, patients with HCM tend to have mild or no symptoms. They are either sporadically detected with routine screening, or present after sudden cardiac arrest. As patients with HCM age, some begin to show mild symptoms of their weakened heart muscle, including difficulty breathing, easy fatigue, racing heart beats, or passing out.
The prognosis of HCM is quite poor. Most succumb to a life threatening arrhythmia, stroke, or congestive heart failure. The young seem to be at highest risk of sudden cardiac death, while death due to stroke or heart failure is seen more commonly in middle to older aged patients. Overall, patients with HCM have a death rate of 12 percent over a seven-year period from the time of diagnosis.
A third type is restrictive cardiomyopathy (RCM). Unlike DCM and HCM, patients with RCM actually have normal sized hearts with normal squeezing function, yet the heart muscle is stiff and is unable to relax. These stiff hearts are unable to appropriately fill with blood and are therefore unable to pump sufficient blood to the body.
The causes of RCM include; radiation exposure, chemotherapy, genetic heart muscle diseases, and rarely sarcoidosis and amyloidosis. Unlike the other causes of cardiomyopathy, RCM tends to have an older age of onset, and a female preponderance. The symptoms of RCM are similar to those of other types of cardiomyopathy, including fatigue, weakness, difficulty breathing and weight gain. Unique to RCM is leg and abdominal swelling.
The prognosis of RCM is equally poor, with advanced age and signs of congestive heart failure being the mortality highest risks. The overall survival ten years from diagnosis is only 37 percent. Like other cardiomyopathies, the cause of death is usually heart failure, stroke or life-threatening arrhythmias.
The final group, miscellaneous cardiomyopathy, is a collection of quite rare and diverse conditions. These include long-standing fast heart rates (tachycardia-mediated cardiomyopathy) and ARVD in which the heart muscle develops lethal patches of fatty tissue deposits. Another very rare condition is Takotsubo's cardiomyopathy, in which a sudden emotionally traumatizing event leads to a localized region of muscle weakness. This condition is more commonly seen in Asian populations and has appropriately been termed “broken heart syndrome.”
The treatment of all cardiomyopathies is largely the same, being optimal medical therapy. The goal of medical therapy is to reduce the heart's overall work load. This is accomplished with several classes of medications including: heart rate medications (beat blockers, calcium channel blockers and digoxin), blood pressure medications (diuretics, ACE-inhibitors, ARBs), and medications that regulate blood volume (diuretics). In some patients, their weakened heart muscle significantly increases the risk of developing fatal blood clots. Therefore, many require long- term blood thinners.
In some instances, surgical procedures like implantation of a pacemaker may be necessary to regulate heart rate and optimize cardiac function. In patients with the obstructive version of HCM, surgical resection of the obstructive portion of the hypertrophied heart muscle may reduce the obstruction to forward blood flow and significantly improve symptoms. More recently, this surgical procedure has been replaced by a catheter based procedure in which concentrated ethanol is injected directly into this obstructive muscle. Soon after the injection, the muscle dies and significantly shrinks, ultimately correcting the obstruction.
Lastly, one of the most common causes of death in cardiomyopathy patients is life threatening arrhythmias. In addition to the above medications, the best therapy for these arrhythmias is an implantable cardiac defibrillator (ICD). These are permanent devices which can detect and shock a life threatening arrhythmia in less than 10 seconds.
In advanced cardiomyopathy, selected patients are referred for cardiac transplantation. The overall prognosis of patients with successful heart transplantation is markedly improved over those patients with medical therapy alone. The usual limitation is the long transplant list, most commonly due to a paucity of available donors.
Long-term care includes strict medical therapy and close follow-up with a cardiologist. Additionally, some cardiomyopathies are genetic, which therefore require screening of immediate family members. The follow-up diagnostic tests usually include EKG#s and sonograms of the heart (echocardiograms) to assess for significant changes.
Although cardiomyopathies are somewhat uncommon in the Unites States, they are critically important diseases with high long-term morbidity and mortality. When suspected, patients and their family members will need to work closely with their cardiologist to battle this disease.
Dr. David M. Donaldson is an Auburn native and currently a
cardiologist at Massachusetts
General Hospital in Boston
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