John P. Cunha, DO, is a U.S. board-certified Emergency Medicine Physician. Dr. Cunha's educational background includes a BS in Biology from Rutgers, the State University of New Jersey, and a DO from the Kansas City University of Medicine and Biosciences in Kansas City, MO. He completed residency training in Emergency Medicine at Newark Beth Israel Medical Center in Newark, New Jersey.
Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.
Arrhythmias are pattern and/or speed changes from the normal heart rhythm. Some patients are totally unaware of their arrhythmias. Others may report symptoms including palpitations, skipping or fluttering sensations, dizziness, fainting,
shortness of breath, or
chest pain.
In both tachycardias and bradycardias, lack of blood flow to the brain,
the coronary arteries, or the rest of the body can occur. Lack of blood
flow to the brain can cause dizziness or loss of consciousness (syncope).
Lack of blood supply to the coronary arteries can cause chest pain or
pressure (angina). Inadequate blood supply to the rest of the body can
cause weakness and shortness of breath.
What are the causes of arrhythmias?
In some patients, arrhythmias are caused by diseases of the heart
muscle, valves or coronary arteries. In others, arrhythmias can reflect
disease of the electrical system of the heart only, while the rest of the
heart is healthy. Other causes of arrhythmias include medications, alcohol
excess, excessive levels of thyroid hormone, low blood oxygen levels,
stress, and
smoking.
Atrial tachycardias
Examples of atrial tachycardias include atrial fibrillation, atrial
flutter, and paroxysmal atrial tachycardia (PAT). These arrhythmias occur
because of electrical disturbances in the atria and/or the AV node,
leading to fast heart beats.
Atrial fibrillation is a common atrial tachycardia. In atrial fibrillation, multiple, rapid, and chaotic electrical signals fire rapidly from different areas in the atria, rather than from one single area pacemaker at the SA node. These signals in turn cause rapid irregular contractions of the ventricles. Causes of atrial fibrillation include heart attack, high blood pressure,
heart failure, mitral valve diseases (such as mitral valve prolapse), overactive thyroid, blood clots in the lung (pulmonary embolism),
alcohol excess,
emphysema, and inflammation of heart lining (pericarditis). For further information, please refer the
Atrial Fibrillation article.
Atrial flutter is a more regular (less chaotic) version of atrial fibrillation as the electrical signal initiates in the atria..
Conditions that cause atrial fibrillation can also cause atrial flutter.
Treatment of atrial flutter and atrial fibrillation are also similar (see
below).
Paroxysmal atrial tachycardia (PAT) represent bouts of rapid, regular
heart beating originating in the atrium. Patients with PAT are believed to
have abnormalities in the AV node "relay station" that lead to
rapid firing of the electrical impulses from the atrium which bypass the
AV node under certain conditions. These conditions include alcohol excess,
stress, caffeine, overactive thyroid or excessive thyroid hormone intake,
and certain drugs. PAT is an example of an arrhythmia where the
abnormality is in the electrical system of the heart, while the heart
muscle and valves may be normal.
Ventricular Arrhythmias
Ventricular arrhythmias are rapid arrhythmias that originate in the lower chambers of the heart (the ventricles). Ventricular arrhythmias include ventricular tachycardia and ventricular fibrillation. Ventricular tachycardia is a rapid regular arrythmia which originates from an area of the ventricle. Ventricular fibrillation is an irregular arrhythmia that is a result of multiple rapid and chaotic electrical signals firing from many different areas in the ventricles.
Ventricular tachycardias and fibrillation are life threatening arrhythmias most commonly associated with heart attacks or scarring of the heart muscle from previous heart attack. For further information, please read the
Heart Attack article. Less
common causes of ventricular arrhythmias include severe heart muscle
failure (cardiomyopathy), medication toxicity
[such as digoxin (Lanoxin) toxicity],
medication side effects, and
blood electrolyte disturbances (such as low
potassium level). Ironically, some medications used in treating heart
arrhythmias can cause ventricular tachycardias (see the treatment section
below).
Bradycardias
Diseases of the SA node, the AV node, and the conduction system in the
ventricles can lead to slow arrhythmias (bradycardias).
Calcium channel
blockers, such as verapamil (Calan),
beta-blockers, such as
propanolol (Inderal), and digoxin (Lanoxin) can cause bradycardias. These
medications can also seriously aggravate bradycardias in patients with
existing diseases of the SA node, AV node and other parts of the conduction
system. Even though
some patients experience no ill effects from bradycardias, serious
bradycardias can lead to low blood pressure (shock), and passing out
(syncope).
Premature Contractions
Early heartbeats that don't originate from the SA node pacemaker are called premature contractions. Premature atrial contractions (PACs) and premature ventricular contractions (PVCs) can be caused by stress, caffeine,
cigarette smoking, and excessive alcohol intake. Generally, PACs and PVCs, when they are infrequent and isolated, are not associated with significant heart disease.
Panic attacks are sudden feelings of terror that strike without warning. These episodes can occur at any time, even during sleep. A person experiencing a panic attack may believe that he or she is having a heart attack or that death is imminent. The fear and terror that a person experiences during a panic attack are not in proportion to the true situation and may be unrelated to what is happening around them. Most people with panic attacks experience several of the following symptoms: racing heartbeat, faintness, dizzyness, numbness or tingling in the hands and fingers, chills, chest pains, difficulty breathing, and a feeling of loss or control. There are several treatments for panic attacks.
An arrhythmia is an abnormal heart rhythm. With an arrhythmia, the heartbeats may be irregular or too slow (bradycardia), to rapid (tachycardia), or too early. When a single heartbeat occurs earlier than normal, it is called a prmature contraction.
Angina is chest pain that is due to an inadequate supply of oxygen to the heart muscle.
Angina can be caused by coronary artery disease or spasm of the coronary
arteries. EKG, exercise treadmill, stress echocardiography, stress thallium, and cardiac
catheterization are important tests used in the diagnosis of angina.
Heart attack happens when a blood clot completely obstructs a coronary
artery supplying blood to the heart muscle. A heart attack can cause chest pain, heart failure, and electrical
instability of the heart.
Hypoglycemia is a syndrome caused by low blood sugar. Symptoms of hypoglycemia include palpitations, trembling, intense hunger, sweating, nervousness, and weakness. Consuming lifesavers, table sugar, soda, and juice are good treatment options for hypoglycemia.
Mitral valve prolapse (MVP) is also also known as "click murmur syndrome" and "Barlow's syndrome." Mitral valve prolapse is the most common heart valve abnormality. Signs and symptoms of mitral valve prolapse include: fatigue, palpitations, chest pain, anxiety, and migraine headaches. Echocardiography is the most useful test for mitral valve prolapse. Most patients do not need any treatment, however, patients with severe prolapse may need treatment.
Potassium is an essential electrolyte necessary for cell function. Low potassium (hypokalemia) may be caused by diarrhea, vomiting, ileostomy, colon polyps, laxative use, diuretics, elevated corticosteroid levels, renal artery stenosis, and renal tubular acidosis, or other medications. Symptoms of low potassium include weakness, aches, and cramps of the muscles. Treatment is dependant upon the cause of the low potassium (hypokalemia).
Premature ventricular contractions (PVCs) are premature heartbeats originating from the ventricles of the heart. PVCs are premature because they occur before the regular heartbeat. There are many causes of premature ventricular contractions to include: heart attack, high blood pressure, congestive heart failure, mitral valve prolapse, hypokalemia, hypoxia, medications, excess caffeine, drug abuse, and myocarditis.
Marfan syndrome is hereditary condition affecting connective tissue. A person with Marfan syndrome may exhibit the following symptoms and characteristics: dislocation of one or both lenses of the eye; a protruding or indented breastbone; scoliosis; flat feet; aortic dilatation; dural ectasia; stretch marks; hernia; and lung collapse. Though there is no cure for Marfan syndrome, there are treatments that can minimize and sometimes prevent some complications.
Heart rhythm disorders vary from minor palpitations, premature atrial contractions (PACs), premature ventricular contractions (PVCs), sinus tachycardia, and sinus brachycardia, to abnormal heart rhythms such as tachycardia, ventricular fibrillation, ventricular flutter, atrial fibrillation, atrial flutter, paroxysmal supraventricular tachycardia (PSVT), Wolf-White-Parkinson syndrome, brachycardia, or heart blocks. Treatment is dependant upon the type of heart rhythm disorder.
Aortic valve stenosis is an abnormal narrowing of the aortic valve of the heart. The causes of aortic stenosis are wear and tear of the valve in the elderly, congenital, or scarring or scarring of the aortic valve from rheumatic fever. Symptoms include angina, fainting, and shortness of breath. Treatment is dependant upon the severity of the condition.
Heart valve disease occurs when the heart valves do not work the way they should. Symptoms of valve disease include shortness of breath, weakness or dizziness, discomfort in your chest, palpitations, swelling of your ankles, feet or abdomen, and rapid weight gain.
A heart murmur is the sound generated when blood flow within the heart is not smooth. Causes of heart murmurs can be functional, congenital, or caused heart valve conditions. Symptoms of a heart murmur may be none, or may include chest pain, shortness of breath, and arm, leg, and ankle swelling. Treatment of a heart murmur depends on the cause.
Wolff-Parkinson-White syndrome is a condition in which abnormal electrical pathways in the heart cause arrhythmias. Symptoms of Wolff-Parkinson-White syndrome include tachycardia, dizziness, palpitations, fainting, and shortness of breath. Wolff-Parkinson-White syndrome is a common cause of paroxysmal supraventricular tachycardia. Wolff-Parkinson-White syndrome is caused by mutations in the PRKAG2 gene.
Ticks are known transmitters of disease to humans and animals. Tick-borne diseases include Lyme disease, Rocky Mountain spotted fever, Q fever, tularemia, babesiosis, and Southern tick-associated rash illness. Infected ticks spread disease once they've bitten a host, allowing the pathogens in their saliva and mouth get into the host's skin and blood. Tick bites are typically painless, but the site of the bite may later itch, burn, turn red, and feel painful. Individuals allergic to tick bites may develop a rash, swelling, shortness of breath, numbness, or paralysis. Tick bite treatment involves cleaning and applying antibiotic cream.
Paroxysmal supraventricular tachycardia (PSVT) is an abnormal conduction of electricity in particular areas of the heart. PSVT was referred to at one time as paroxysmal atrial tachycardia or PAT, however, the term PAT is reserved for as specific heart condition. Symptoms of PSVT include weakness, shortness of breath, chest pressure, lightheadedness, and palpitations. PSVT is treated with medications or procedures that return the heart to its normal electrical pattern.
Heart failure is caused by many conditions including coronary artery disease, heart attack, cardiomyopathy, and conditions that overwork the heart. Symptoms of heart failure include congested lungs, fluid and water retention, dizziness, fatigue and weakness, and rapid or irregular heartbeats.
Chagas disease is an infection caused by the T. cruzi parasite. Symptoms of Chagas disease include rash, swollen lymph nodes, fever, fatigue, nausea, vomiting, and the Romaña sign. An ELISA test is used to diagnose Chagas disease. Treatment depends upon the phase of the disease and the patient's age.
Schistosomiasis (snail fever), a disease caused by parasites, causes a variety of symptoms and signs, such as cough, rash and bloody diarrhea. Praziquantel is used in the treatment of schistosomiasis.
Dilated Cardiomyopathy is a condition where the heart's ability to pump blood is decreased because the heart's main pumping chamber is enlarged and weakened. Symptoms of dilated cardiomyopathy include chest pain, heart failure, swelling of the lower extremities, fatigue, weight gain, fainting, palpitations, dizziness and blood clots.
Hypertrophic cardiomyopathy (HCM) affects many people today. Many people with HCM have no symptoms or only minor symptoms, and live a normal life. Other people develop symptoms, which progress and worsen as heart function worsens.
Restrictive cardiomyopathy, the rarest form of cardiomyopathy, is a condition in which the walls of the lower chambers of the heart (the ventricles) are abnormally rigid and lack the flexibility to expand as the ventricles fill with blood.
The pumping or systolic function of the ventricle may be normal but the diastolic function (the ability of the heart to fill with blood) is abnormal. Therefore, it is harder for the ventricles to fill with blood, and with time, the heart loses the ability to pump blood properly, leading to heart failure.
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