Palpitations Case File

Palpitations Case File

Eugene C. Toy MD, Donald Briscoe, MD, FA  AFP, Bruce Britton, MD, Joel J. Heidelbaugh, MD, FA  AFP, FACG

Case 42

A 35-year-old woman presents to your office complaining of skipped or "irregular heartbeats" for the past few weeks. She paid little attention to her symptoms because she had been under job-related stress and she thought these symptoms would disappear. Instead, her occasional skipped beats increased in frequency to twice a day, lasting up to 2 minutes per episode. Her father, who suffered from heart disease, urged her to see a doctor. She denied chest pain, shortness of breath, or dizziness. She consumes about two cups of caffeinated coffee per day. She recently tried some over-the-counter (OTC) diet pills to lose weight, but stopped taking them when her symptoms became more frequent. On examination, she has a normal body mass index (BMI), her blood pressure is 130/85 mm Hg, heart rate is 92 beats/min, and temperature is 98.6°F (37°C). Head, ears, eyes, nose, and throat (HEENT) examination is normal. No conjunctiva! pallor or injection is noted. Neck examination is without thyromegaly, nodule, or mass and without jugular venous distension or bruit. Lung examination is bilaterally clear to auscultation. Cardiac examination reveals regular rate and rhythm with normal S1 and S2 and without midsystolic click or murmur. Abdominal examination is unremarkable. Examination of the extremities reveals palpable symmetric distal pulses in all four extremities. Neurologic examination reveals no resting tremor. Reflexes are normal.

⯈ What is your most likely diagnosis?

⯈ What is your next diagnostic step?

⯈ What is the next step in therapy?

ANSWER TO CASE 42

Palpitations

Summary: A 35-year-old woman presents to your office with palpitations for 2 weeks that have increased in frequency. Her symptoms are not associated with chest pain, syncope, dyspnea, or dizziness. She has no pertinent past medical history. She has the potential triggers of caffeine consumption, diet pill use, and stress. Family history of heart disease is also noted. Her examination is normal.

• Most likely diagnosis: Cardiac dysrhythmia, benign.
• Next diagnostic step: Obtain 12-lead ECG.
• Next step in therapy: Restrict caffeine and alcohol; eliminate any amphetamine based stimulants and/or diuretics; keep a diary of symptoms or possible triggers; follow-up with patient in 2 weeks. If symptoms persist, additional workup may be required.

ANALYSIS

Objectives

1. Define palpitations.
2. Identify benign rhythm disturbances and those associated with sudden cardiac death.
3. Identify the most common structural heart diseases associated with sudden cardiac death.
4. Develop a rational approach that takes into account cardiac and noncardiac causes for palpitations.

Considerations

This 35-year-old woman gives a history of frequent palpitations and otherwise appears healthy (normal physical examination) without a history of associated dizziness or syncope. Because she is also younger than the age of 50 (thus at low risk for coronary artery disease), she is most likely to have a nonthreatening cause for her symptoms and can be worked up on an outpatient basis.

This history is the most important part of the workup in this patient. We are given clues to noncardiac factors that may contribute to palpitations, including caffeine consumption, use of diet pills, job-related stress, and possibly stress surrounding her father's own health problems. However, stress should not be assumed to be the only cause of her symptoms. Anemia should be considered if there is a history of fatigue, light-headedness, gastrointestinal (GI) blood loss, or menorrhagia.

Family history can be very important because some dysrhythmias, such as familial prolonged QT syndrome, can run in families. A family history of premature cardiac death (or unexplained sudden death) should be sought, as hypertrophic cardiomyopathy is an autosomal dominant disorder and may not always demonstrate a heart murmur when the patient is examined.

If this woman were to have a midsystolic click associated with or without a late systolic murmur, the physician should consider the presence of mitral valve prolapse (MVP) syndrome. Usually asymptomatic, it is the most common valvular heart defect in the United States, occurring in 3% to 6% of the population. Because MVP is common, the presence of palpitations may or may not be comorbid with this condition. Nonetheless, patients may present with palpitations, fatigue, chest discomfort (not typical of angina), and dyspnea with this valvular finding. This symptom complex is defined as mitral valve prolapse syndrome. These patients may also present with panic attacks or manic-depressive syndromes. Two percent of patients with MVP will have complications resulting in progression to mitral regurgitation with subsequent left-sided two-chamber enlargement, atrial fibrillation (if the left atrium becomes enlarged), left ventricular dysfunction leading to heart failure, pulmonary hypertension, and infective endocarditis. For these reasons, a surface echocardiogram is recommended at baseline when suspicion for MVP is identified.

Approach To:

Palpitations

DEFINITIONS

PALPITATIONS: A subjective sensation of unduly strong, slow, rapid, or irregular heartbeats that may be related to cardiac arrhythmias. The sensation may last seconds, minutes, hours, or days and is often intermittent. They are common, usually not dangerous, and may be the result of a change in the heart's electrical system.

CLINICAL APPROACH

Etiologies

Approximately 40% of patients complaining of palpitations have an underlying primary rhythm disturbance. An underlying mental health problem (anxiety or panic disorder) is the cause in 31 % of symptomatic patients. Drugs (prescription, recreational, or over-the-counter) cause 6% of palpitations; intrinsic structural problems with the heart are the cause of 3%; 4% have noncardiac causes; and the remaining 16% have no identifiable cause.

The largest group has some type of primary rhythm disorder:

• Premature atrial contractions (PAC)-most common etiology of palpitations
• Premature ventricular contractions (PVC)
• Sinus tachycardia
• Sinus bradycardia
• Wolff-Parkinson-White (WPW) syndrome
• Sick sinus syndrome
• Supraventricular tachycardias (SVT)
• Ventricular tachycardia (VT)

These rhythm disturbances can be seen throughout childhood and adulthood. Supraventricular tachycardia refers to any tachycardia that is not ventricular in origin. This definition includes physiologic sinus tachycardia which can be a normal reaction to stress and a variety of noncardiac conditions such as fever and hyperthyroidism. In the clinical setting however, it is used practically as a synonym for paroxysmal supraventricular tachycardia (PSVT). This term refers to those SVTs that have a sudden, almost immediate onset and regular rhythm. A person experiencing PSVT may feel their heart rate go from 60 to 200 beats/min instantaneously, often in response to a quick movement such as picking something up from the floor. Because physiologic sinus tachycardia has a gradual onset and atrial fibrillation (AF) and multifocal atrial tachycardia (MAT) are irregular rhythms, they are excluded from the PSVT category.

PSVTs are most commonly atrioventricular (AV) nodal reentrant tachycardias or part of WPW syndrome, which may be"concealed" (ie, not evident on the resting ECG). WPW syndrome is caused by an accessory track between the atria and ventricles that conducts electrical impulses in addition to the AV node. The classic ECG finding is a slurring on the upstroke of the QRS complex known as a delta wave. WPW can cause dangerous arrhythmias and lead to sudden cardiac death.

Brugada syndrome is an ion channel disorder that is most common in Asian males. Characteristic findings on an ECG include a right bundle branch block pattern and an elevation at the J point that is greater than 2 mm, with a slowly descending ST segment in conjunction with flat or negative T waves in the right precordial leads V1, V2, or V3. It can cause dangerous arrhythmias that results in sudden death.

Sick sinus syndrome usually involves a dysfunction of the sinoatrial (SA) node that leads to bradycardia and can cause fatigue and syncope. Patients, however, can also have a tachycardia-bradycardia variety of sick sinus syndrome in which they also experience supraventricular tachycardia with its associated symptoms of palpitations and angina pectoris.

Patients with long QT interval syndrome are at increased risk for ventricular arrhythmias and sudden cardiac death (SCD). Long QT syndrome is caused by mutations in multiple genes and can have an autosomal dominant pattern. It is seen more commonly in females. Patients with this syndrome will present with either palpitations and/ or syncope and have a family history of syncope or sudden death. Prolonged QT interval is defined as QTc1 470 ms in men or greater than 480 ms in women. Any patient with a QT interval greater than 500 ms is at increased risk for dangerous dysrhythmias. Prolonged QT intervals may also be the result of the use of certain medications such as quinidine, procainamide, sotalol, amiodarone, and tricyclic antidepressants.

QTc1 is defined as measured QT interval corrected for heart rate:

Benign rhythm disturbances include premature atrial contractions, sinus tachycardia, and sinus bradycardia appropriate for activity/stress level, sinus pauses less than 3 seconds, and isolated unifocal PVCs. However, PVCs in the presence of known cardiac disease, metabolic disease, or the presence of worrisome symptoms (such as near syncope, syncope, or seizures) require aggressive workup because of the risk of ventricular tachycardia or fibrillation. PVCs occurring at rest and disappearing with exercise are usually benign, commonly seen in athletes, and require no investigation.

Psychiatric causes of palpitations are always considered in the differential diagnosis for palpitations and may be missed if not screened for in the initial history. Panic disorder is seen more often in women of childbearing age. Patients with panic attacks commonly present to emergency departments with complaints of chest pain, shortness of breath, and palpitations. They will report brief episodes of overwhelming panic or sense of impending doom associated with tachycardia, dyspnea, or dizziness. Still, these complaints may be identical to primary rhythm disturbances and deserve formal workup and cardiac risk stratification.

Cardiac or structural causes of palpitations include cardiomyopathy, atrial or ventricular septa! defects, congenital heart disease, mitral valve prolapse, pericarditis, valvular heart disease (eg, aortic stenosis, aortic insufficiency), and congestive heart failure. The presence of restrictive, hypertrophic, or dilated cardiomyopathies may lead to sudden cardiac death.

Hypertrophic obstructive cardiomyopathy (HOCM) is the most common cause of sudden cardiac death in adolescents in the United States and is often not detected on routine physical examination. These patients may present with chest pain, syncope, and palpitations, but are commonly asymptomatic. Hypertrophic cardiomyopathy may be passed down as an autosomal dominant trait. A heart murmur, if present, will usually be systolic and will be accentuated by Valsalva maneuver. Echocardiography demonstrating a thickened intraventricular septum with ventricular obliteration remains the gold standard for diagnosis. There is no evidence to suggest routine echocardiography screening in athletes to detect HOCM, and such a practice has been shown not to be cost-effective.

Marfan syndrome should be suspected in patients who are tall and have scoliosis, pectus excavatum, long, thin digits (arachnodactyly), high-arched palate, and an arm span exceeding their height. Mitral valve prolapse may be seen in patients with Marfan syndrome. These patients often have aortic root dilations and are at risk for aortic arch aneurysm rupture. The diagnosis can be confirmed by echocardiography.

Noncardiac causes of palpitations may be suggested by the history and examination. Noncardiac etiologies include anemia, electrolyte disturbances, hyperthyroidism, hypothyroidism, hypoglycemia, hypovolemia, fever, pheochromocytoma, pulmonary disease, and vasovagal syncope. Laboratory screening includes a complete blood count (CBC), comprehensive metabolic panel, and thyroid-stimulating hormone (TSH). If a pheochromocytoma is suspected, a 24-hour urine collection for catecholamines and metanephrines is indicated.

Numerous medications and substances may contribute to palpitations including alcohol, caffeine (especially energy drinks), illicit drugs (cocaine), tobacco, decongestants (eg, pseudoephedrine, often found in OTC and herbal weight loss drugs), diuretics (causing electrolyte disturbances), digoxin, β agonists ( eg, albuterol), theophylline, and phenothiazine. Patients should be questioned about their use of OTC medications, herbs, and supplements, as they often will not provide this information unless specifically asked. It is always reasonable to ask the patient to bring the herbal preparations and supplements that they are taking to the clinic so that the physician can review the ingredients.

CLINICAL PRESENTATION

Evaluation of a patient presenting with palpitations should take into account numerous factors. The patient's age at symptom onset is important, as an age older than 50 years should always lead to the consideration of coronary artery disease. However, notwithstanding a patient's age, cardiac risk assessment should occur with every patient. Possible triggers should be pursued, such as medication use, exercise, and psychosocial stress. Physicians should pay particular attention to palpitations associated with syncope, as these are usually pathologic and hospitalization with cardiac monitoring and cardiology evaluation should be considered.

The clinical examination should focus on vital signs (blood pressure and heart rate), including orthostatic readings if suggested by history. The thyroid gland should be examined for abnormalities such as goiter, nodule, or bruit. The presence of resting tremor or brisk reflexes should also lead the physician to consider hyperthyroidism.

The cardiac examination should be thorough. The point of maximum impulse should be palpated, as displacement may suggest cardiomegaly. The rate and rhythm, along with any irregularities, should be noted, and an ECG should be obtained. For example, an irregularly irregular rhythm is suggestive of atrial fibrillation whereas an occasional extra beat may be PACs or PVCs. Extra sounds, such as the midsystolic click of mitral valve prolapse or any murmurs consistent with valvular pathology, should also be documented and an echocardiogram should be obtained.

A 12-lead electrocardiogram is appropriate in all patients with palpitations, even if they are symptom free during the physician encounter. The presence of left ventricular hypertrophy, atrial enlargement, atrioventricular block, old myocardial infarction, and delta waves (as seen in WPW syndrome) should trigger additional testing. Prolonged QT intervals increase the risk for dangerous rhythm disturbances and require a thorough review of medications that can cause this, as well as consultation with a cardiologist or cardiac electrophysiologist.

Other cardiac testing may be appropriate based on the history, examination, and results of the initial evaluation. Ambulatory electrocardiographic rhythm monitoring can be accomplished for periods of 24 to 72 hours using a Holter monitor. A cardiac event monitor can be worn by a patient for up to 30 days and might be useful when the palpitations do not occur daily. The monitor is worn continuously and activated by the patient when palpitations are felt.

An echocardiogram can be useful in identifying patients with suspected structural abnormalities of their heart chambers or heart valves, which could trigger heart rhythm disturbances. These findings could be missed on physical examination. A transesophageal echocardiogram should be performed to look for a thrombus prior to cardioversion. Exercise stress testing in age- and risk-appropriate patients may be important for identifying dysrhythmias triggered by exercise. This test may be of particular importance in patients with suspected coronary artery disease. Anyone with suspected structural problems should be evaluated by a surface echocardiogram prior to undergoing stress testing. Patients with suspected hypertrophic cardiomyopathy or severe aortic stenosis should avoid exercise stress testing, as they may develop heart rhythm disturbances which may be nonrecoverable. Finally, electrophysiology studies may be needed to recreate rhythm disturbances and identify hyperactive foci and accessory tracts such seen in WPW syndrome. These areas can subsequently be electrically ablated.

TREATMENT

The treatment of a given patient's symptoms is dependent on the etiology. If palpitations are medication related, the offending agent should be weaned or stopped. Anxiety may be treated by a combination of pharmacologic and nonpharmacologic interventions. If the problem is structural cardiac disease, referral to a cardiologist is usually indicated.

β-Blockers or calcium channel blockers are often used as first-line therapy for primary supraventricular rhythm disturbances. If symptoms are short-lived or episodic, short-acting negative chronotropics, such as short-acting β-blockers, can be used on an as-needed basis.

Symptomatic PSVT can often be self-treated by patients with recurrent episodes by several vagal stimulation techniques. Carotid sinus massage, Valsalva maneuver, and cold applications to the face (diver's reflex) can trigger vagus nerve stimulation, which may break an episode of SVT. When these are unsuccessful, IV adenosine is often administered. If the adenosine terminates the SVT, then the arrhythmia is most likely a reentry SVT. If it does not, then the rate may be slowed down with β-blockers or calcium channel blockers. At that point, consultation with a cardiologist should be sought.

Chronic atrial fibrillation should be treated with medication to keep the ventricular rate below 100 beats/min; these agents for rate control are often β-blockers or calcium channel blockers. A return to normal sinus rhythm may be attempted with electrical cardioversion or antiarrhythmic drugs, such as amiodarone, sotalol, or with class lC drugs such as flecainide and propafenone. Class lC drugs should not be used in the presence of structural cardiac disease or cardiac hypertrophy. A transesophageal echocardiogram (TEE) should be done prior to cardioversion in order to rule out the presence of a thrombus that might dislodge with the cardioversion. Rhythm control and rate control have similar rates of stroke and mortality. Rate control is often the preferred strategy for many patients. Most patients with atrial fibrillation will also require anticoagulation, as they are at an increased risk of embolic stroke from blood clots that form in the cardiac atrium, in accordance with the CHADS2-VASC risk calculation.

Ventricular arrhythmias can be extremely dangerous and usually require prompt treatment. Ventricular fibrillation is not compatible with life and needs to be treated immediately with electrical defibrillation. Patients with ventricular tachycardia, who are unstable, need to be electrically cardioverted. Amiodarone should be given to a patient with stable ventricular tachycardia and in patients who were converted back into a sinus rhythm through cardioversion. Lidocaine should be used in place of amiodarone in patients who are allergic to iodine. The most common cause of ventricular arrhythmias is ischemia.

An automatic implantable cardioverter-defibrillator (AICD) is indicated in patients with conditions that commonly result in ventricular fibrillation or tachycardia leading to sudden death. Some of these conditions are advanced dilated cardiomyopathy, long QT syndrome, hypertrophic cardiomyopathy, and Brugada syndrome.

CASE CORRELATION

• See also Case 20 (Chest Pain).

COMPREHENSION QUESTIONS

42.1 A 35-year-old man who has never had a physical examination comes to clinic. He recently moved to the area and needs to establish with a new physician. He has had no previous medical problems to date and no pertinent family history. He denies any changes in bowel or bladder habits and does not smoke or drink alcohol. When prompted he says that he has noticed a "fluttering" in his chest for past 3 months that spontaneously resolves. He has had increased stress at work and has been drinking six cups of caffeinated coffee a day to complete his workload. He has not had time to exercise and his diet consists of what he can find in the office cafeteria. He denies any history of anxiety. Which of the following is the most common underlying etiology of his palpitations?

A. Medication

B. Structural heart disease

C. Coronary artery disease

D. Primary rhythm disturbance

E. Idiopathic

42.2 A 42-year-old asymptomatic woman is noted to have an abnormal finding on ECG. Which of the following is an indication for referral to a cardiologist or cardiac electrophysiologist?

A. PVCs on a resting ECG that resolve with exercise

B. Delta waves on an ECG

C. Isolated unifocal PVCs found on ECG

D. Sinus arrhythmia

42.3 Which of the following patients should undergo an exercise stress test for evaluation of his palpitations?

A. A 60-year-old man with symptomatic PVCs but without syncope

B. A 35-year-old man with hypertrophic cardiomyopathy seen on an echocardiogram

C. A 32-year-old, tall, slender man with pectus excavatum and a midsystolic click on examination

D. A 68-year-old man with suspected aortic stenosis

42.4 A 16-year-old adolescent boy comes to your office for a sports physical. He is planning to try out for his high school football team but first needs medical clearance. He has no cardiovascular complaints and his history is unremarkable, except for a family history which includes an uncle dying suddenly while jogging at age 25. His physical examination is unremarkable except for a harsh systolic murmur loudest over his left lower sternal border which increases with the Valsalva maneuver. You obtain an ECG which shows left ventricular hypertrophy. Which of the following is the most appropriate next step in management?

A. An exercise stress test

B. An echocardiogram

C. A chest x-ray

D. A coronary catheterization

E. Reassurance that he is cleared to play football

42.5 You are called to the bedside of a patient who was complaining of chest pain. When you get there you find the patient confused and not answering questions. The nurse informs you that the patient was speaking coherently only several minutes ago. The patient's pulse is 180 beats/min, his systolic blood pressure is 60 mm Hg, and his diastolic blood pressure cannot be measured. Telemetry reveals supraventricular tachycardia. Which of the following is the most appropriate next step in the management of this patient?

A. Adenosine

B. Cardiology consultation

C. Emergent electrical cardioversion

D. Negative chronotropic agent

E. 12-lead ECG

ANSWERS

42.1 D. Primary rhythm disturbances are the most common cause of palpitations, making up approximately 40% of cases. Other common causes include psychiatric etiologies (eg, anxiety, panic disorder), medications, metabolic (eg, electrolytes, thyroid hormone imbalance), and structural heart disease. Many cases of palpitations remain undiagnosed in spite of appropriate evaluation.

42.2 B. The presence of delta waves indicates WPW syndrome and the presence of an accessory tract that can be ablated by an electrophysiologist.

42.3 A. A 60-year-old with PVCs, especially if they are of new onset, may be showing the initial presentation of coronary artery disease and should undergo stress testing. All of the other conditions listed are contraindications to stress testing.

42.4 B. This young man has signs suggestive of hypertrophic cardiomyopathy. The confirmatory test for it is an echocardiogram. Coronary catheterization and stress testing are tests for coronary artery disease and not recommended for this patient. A β-blocker or calcium channel blocker would worsen the patient's hemodynamic status. Adenosine is indicated for supraventricular tachycardia with a narrow QRS complex and not ventricular tachycardia.

42.5 C. This patient has ventricular tachycardia with clinical deterioration and hemodynamic instability. He needs immediate electrical cardioversion. If the patient was in a stable ventricular tachycardia, then medical cardioversion could be conducted using intravenous amiodarone.

CLINICAL PEARLS

⯈ Patients with palpitations require an in-depth evaluation into potential cardiac etiologies, as psychosocial stress cannot be assumed as the sole etiology.

⯈ Consider Marfan syndrome in a tall patient with long arms, long fingers, and wears glasses.

⯈ A 24- to 72-hour Holter monitor is appropriate in a patient with frequent (eg, daily) palpitations; a 30-day event monitor is a better test in someone with infrequent episodes.

⯈ Hypertrophic cardiomyopathy is the most common cause of sudden cardiac death in adolescents. An adolescent with a systolic heart murmur that increases in intensity with Valsalva maneuver should have his/her activity restricted until a diagnostic echocardiogram can be performed.

⯈ Unexplained prolonged QT interval syndrome requires further evaluation.

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