The purpose of this article is to educate nurse practitioners about the diagnosis of actue chest pain. After reading this article, the nurse practitioner should be able to:
- List the most common differential diagnoses for chest pain;
- Identify the tools for diagnosing chest pain;
- Discuss at least five different symptoms of chest pain; and
- List three lab tests that assist with the diagnosis of MI.
Eight Steps to Definitive Diagnosis
Chest pain is one of the most difficult and complex symptoms to diagnose.1 It is a presenting symptom for multiple possible disease processes, including cardiovascular, pulmonary, gastrointestinal, musculoskeltal and psychiatric problems. Nurse practitioners must be able to quickly evaluate whether chest pain signals a life-threatening cardiac event or an episode of non-cardiac pain. Diagnosis is further complicated by the patient's perception of pain intensity, which may vary depending on age, gender, culture and the presence of diseases such as diabetes.
The American Heart Association has done an excellent job of educating the public that chest pain may be an early warning sign of a heart attack, and that prompt treatment can mean the difference between life and death. This awareness has encouraged more people not to procrastinate about seeking medical care. Studies show that chest pain is one of the most frequent reasons for a visit to the provider's office or emergency department.1
Of primary consideration is whether a patient's chest pain is being caused by acute myocardial infarction (AMI). Approximately 1.1 million AMIs occur annually, with 2% to 8% missed as a diagnosis. More malpractice dollars are awarded for missed myocardial infarction than for any other diagnosis.2 Several studies have concluded that between 2% and 5% of all patients with AMI are inadvertently sent home from the ED. Up to 30% of patients with chest pain suggestive of angina have normal coronary angiograms. In addition, many patients who do not have significant coronary artery disease continue to have chest pain and to seek emergency evaluation.3
Clinical Policy for Chest Pain
In recognition of the complexity of differential diagnosis for chest pain, the American College of Emergency Physicians published a clinical policy for the assessment and treatment of chest pain in 1990. With the recent focus on clinical research about heart disease, the college redefined its policy in 1995 to concentrate on diagnoses associated with high morbidity and mortality.1
Initial evaluation of chest pain should be immediate, with prompt therapeutic action. The consequences of delayed treatment are serious. Making the right diagnosis requires you to think much like a detective. Each piece of "evidence"-symptoms, history and physical, test results and clinical judgment-must be carefully evaluated in a focused work-up that systematically narrows the list of potential differential diagnoses (see table).
|Differential Diagnosis of Chest Pain: Possible Causes4
|Angina pectoria, variant angina, unstable angina|
|Aortic valve disease, aortic dissection, thoracic aortic aneurysm|
|Passive hepatic congestion|
|Splenic flexure syndrome|
|Thoracic outlet syndrome|
|Chest wall infection|
A step-by-step process of elimination is required to rule out each potential diagnosis. First evaluate the conditions that carry the greatest risk of morbidity and mortality, and then move on to conditions with less risk.
What carries the most risk? AMI, pulmonary embolism, thoracic aortic aneurysm or dissection, pericarditis or myocarditis, pneumothorax and pneumonia.
Gastroesophageal reflux, esophageal motility disorders, viral pleurisy, gallbladder disease, mitral valve prolapse and psychiatric disorders (such as anxiety or panic attacks) are also serious, but have much less severe implications for the patient's mortality and morbidity.
Eight Steps to a Definitive Diagnosis
Here are eight steps to making a definitive diagnosis in the case of a patient who presents with acute chest pain:
Step 1: Take a Detailed History
The history is the single most important piece of information in the evaluation of chest pain. Identify the patient's risk factors for heart disease, especially evidence of a strong family history. Risk factors for heart disease include: diabetes, hypertension, family history, cigarette use and cocaine use.
Patients at all levels of risk must be evaluated carefully. Even patients at low risk require evaluation for the likelihood of an unstable acute coronary syndrome. Research shows that 4% to 5% of patients with MI are inadvertently missed during the initial evaluation.4
A complete history should include identification of any pre-existing cardiac conditions, hyperlipidemia, medications, allergies, previous surgery, relevant diagnostic studies, recent immobilization, substance abuse and other previous diagnoses of chest pain.
Review the nursing assessment and previous records, including any pre-hospital care, previous medical records or electrocardiogram results.
Step 2: Perform a Physical Assessment
After taking the patient's vital signs-blood pressure, pulse, respirations, pulse oximetry and temperature-evaluate overall appearance, noting any signs of distress, color or moisture, and assessing the thorax, abdomen and extremities. Check for tenderness and the presence of any lesions in the thorax. Identify any distension, bruits, organomegaly, pulsatile masses or tenderness in the abdomen. Evaluate the extremities for color, edema, pulses, tenderness, temperature and signs of IV drug use.
The next steps in the physical include:
Conduct a cardiovascular exam: Evaluate jugular venous distention, pulses, bruits, rhythm, clicks, murmurs, gallops, point of maximum intensity, pericardial rub, hepatojugular reflex, and differential upper extremity blood pressures.
Conduct a pulmonary exam: Listen for rales, rhonchi, wheezing, breath sounds, percussion, quality and regularity of respirations and pleural rub.
Identify the character of the pain: Note the onset, severity, quality, location, radiation, frequency, duration, similarity to or differences from previous episodes, precipitating or migrating factors, relationship to exertion, stress, respiration or movement, jaw pain, and response to pain therapy.
Review any associated symptoms: Note the presence of shortness of breath, dyspnea on exertion, paroxysmal nocturnal dyspnea, orthopnea, nausea, vomiting, diaphoresis, cough, sputum production, hemoptsis, fever, chills, weight change, fatigue, dizziness, syncope, or palpitations.1
Step 3: Determine Whether Transfer to the ED is Necessary
If the patient presents at an office or clinic setting and has chest pain, first evaluate the ABCs (airway, breathing and compression), then begin an ECG. Depending on the results of the ECG, you may decide to transfer the patient to a local hospital emergency department. First copy the ECG, then call the ED to speak with the charge nurse or one of the NPs or physicians on duty. Last, call for an ambulance transport of the patient to the hospital.
At the ED, the assessment begins with taking the patient's vital signs, including pulse oximetry. Note whether there is a difference in upper extremity blood pressures. Order an IV line to administer pain medications and fluids, followed by an ECG. Remember that the ECG is an effective tool, but not a definitive test. Twenty percent of patients having an MI don't show changes on the ECG.5
Step 4: Order Lab Tests
Lab tests provide more evidence to make a better clinical judgment and to narrow the list of differential diagnoses. Several cardiac-specific tests should be ordered, including serial cardiac markers, chemistry 24, complete blood count (CBC) with differential, prothrombin time and partial thromboplastin time. The most frequently used test is the determination of total creatinine kinase and the cardiac isoenzyme CK-MB. These enzymes are released into the circulation after myocardial cell necrosis.5
Here are some general guidelines to follow for lab tests:
Measure total creatinine kinase and CK-MB every 8 hours for the first 24 hours.
LDH rises 24 to 48 hours after MI, peaks at 3 to 5 days, and returns to normal within 10 days.
Tropinin T elevates as early as 3 hours after an MI and peaks in 24 hours.
Myoglobin is among the earliest substance to appear in the bloodstream, usually 1 to 3 hours after MI, and peaks at 3 to 20 hours. This test is the most helpful in early diagnosis of MI.
A CBC can determine the presence of leukocytosis, which is a potential sign of pneumonia, pericarditis, acute chest syndrome, pulmonary embolism and anemia.5
D-dimer can be effective in identifying patients with pulmonary embolism.5
Step 5: Order a Chest X-Ray
A chest X-ray is an inexpensive, noninvasive diagnostic test. It is especially helpful for identifying tumors, aortic aneurysm, pneumothorax, pneumonia and pulmonary edema. The major limitation of a chest X-ray is a possible normal-appearing test when disease is present.
Step 6: Order Arterial Blood Gas Testing
Evaluation of arterial blood gas (ABG) is another diagnostic tool that is useful in ruling out pulmonary-related conditions. Do not order ABG testing for patients who have been given thrombolytic medications. In addition, evaluate for diminished breath sounds, localized dullness to percussion, pleural rub, rales, wheezing and previous evidence of pulmonary embolism.
Step 7: Order an Echocardiogram with Doppler
An echocardiogram with Doppler is a useful, noninvasive test. When ECG findings are nonspecific and you have a clinical suspicion of myocardial ischemia or MI, an echocardiogram is the best diagnostic tool. It is also helpful for evaluating valvular heart disease, pulmonary embolism (PE), pulmonary hypertension and acute chest syndromes.
Step 8: Order VQ Testing
Assess for signs of deep vein thrombosis (DVT) by noting symptoms of leg swelling, pain, tenderness, warmth to the touch or erythema. DVT can contribute to pulmonary embolism and occur without warning. Standard testing to rule out pulmonary embolism is the ventilation-perfusion ratio or ventilation-perfusion scan. In this test, a radiologic technologist takes a scan of the lungs after the patient breathes a radioactive gas to check for ventilation defects, and takes a second scan after an IV injection of radioactive marker to check uniformity of perfusion. A normal scan rules out PE and a high probability result means the patient should receive anticoagulants.4
If the scan shows a low to medium probability, but clinical evidence is high for PE, order a pulmonary angiogram for a definitive diagnosis. A pulmonary angiogram is the gold standard for diagnosing PE.
Acute Myocardial Infarction
A patient who presents with the classic symptoms of AMI will have the following:
Crushing, aching, tightness or viselike sensation of pain in the chest, often radiating to the neck, jaw or left arm
Cool, moist or cyanotic skin
Tachycardia or altered rhythm
Nausea and vomiting in inferior MI
Cardiogenic shock in anterior MI
Bradycardias and heart hiccups in posterior MI.
The ECG findings may show ischemia-T-wave inversion or ST-segment elevation.4
A patient with AMI requires immediate evaluation and identification to determine whether he is a candidate for thrombolytics or angioplasty. The rapidity of treatment for MI is directly related to the mortality of the patient. Thrombolytic therapy should be initiated within 30 minutes of arrival at the ED.
If the ECG results, history and physical are conclusive and you have made a diagnosis of AMI, begin advanced cardiac life support and treatment immediately. Start an IV, order oxygen, ECG, pain medication, lab work and a chest x-ray. Request pharmacologic support with preload and afterload, administration of warfarin (Heparin, Lovenox) to thin the blood, and GPIIa-IIIb thrombolytics (Retavase, Repro) and beta blockers (Lopressor) to slow heart arrhythmias.
If the ECG results show no diagnostic changes, order further lab testing of myoglobin, creatine kinase-MB, troponin I (cTnl) and tropnin T (cTnT).
A patient in whom you suspect an MI should be admitted to the cardiac care unit or stepdown for treatment and observation. Patients under low suspicion may be admitted to a clinical decision unit if the hospital has such an area.5
A pulmonary embolism occurs when a segment of a thrombus breaks away and is carried into the pulmonary circulation, narrowing or blocking an artery. Like MI, it is a challenge to diagnose pulmonary embolism, yet quick action is vital. Approximately 650,000 to 700,000 new cases of PE occur every year, with a mortality rate of 10%. Death frequently occurs within an hour of symptom onset.5
A pulmonary embolism can arise from anywhere in the body, but usually comes from a deep vein in the leg. Other common sites of origin are the pelvis, liver, kidneys and right heart. Between 80% and 95% of patients diagnosed with PE have deep vein thrombosis.5
A thorough history and physical are critical to accurate diagnosis. The classic symptoms of PE are sudden chest pain and sharp pleuritic pain that worsens with coughing, inspiration and movement. Dyspnea is the second most frequent complaint, followed by apprehension, cough, hemoptosis and sweating. The absence of any classic risk factor should not lower your suspicion about the presence of PE. If the pulmonary embolism is large enough, respiratory failure can occur, as can respiratory alkalosis.5
It also is critical to ask about risk factors. The risk factors for PE are:
Surgery lasting longer than 30 minutes within the last 3 months
History of DVT or previous PE
Pregnancy or recent pregnancy
History of pelvis or lower extremity trauma
Oral contraceptive use combined with cigarette smoking
Congestive heart failure
Chronic obstructive pulmonary disease
Acute Aortic Dissection
The next potential diagnosis to evaluate is acute aortic dissection. One of the major differences between MI and acute aortic dissection is the characteristics of the chest pain. MI has a crescendo type of pain, while acute aortic dissection has severe pain at the onset that is described as crushing, burning, tearing or ripping. The pain may radiate to the back, abdomen and flank areas and may affect one or both lower extremities. Typically the patient also presents with shortness of breath, diaphoresis, nausea and vomiting. Syncope occurs as a result of a sudden decrease in cerebral blood flow.
An acute aortic dissection is the disruption of the intima, which results in the shunting of blood through the medial layer of the aorta. Untreated acute aortic dissection is associated with a mortality rate of 90%. Atherosclerosis and cystic medial necrosis are the leading causes of vessel degeneration. In 65% of patients, tears are located in the ascending aorta, distal to the origins of the aortic valve and coronary artery.5
Pericarditis is an inflammation of the pericardium. It is often characterized by the fibrinous thickening of the pericardium. Effusive pericarditis is characterized by production of an exudate. The causes of pericarditis are infectious or noninfectious. The common infectious causes are viruses, tubercluosis and bacteria. Among the numerous noninfectious causes of pericarditis is MI; it occurs in 7% to 16% of all patients after MI. Other causes include lung and breast cancer, leukemia and cardiac surgery.5
When examining the patient, evaluate whether the chest pain is pericardial or retrosternal, sharp or pleuritic. Chest pain associated with pericarditis may worsen with cough or deep inspiration, increase with lying down and ease when sitting upright. The patient may also experience fever, malaise, dyspnea, cough, dizziness and palpitations.
The rupture of an alveolus system or bronchial wall, which displaces free air into the pleural space, causes a pneumothorax. Simple pneumothorax is a less than 25% collapse of the affected lung. The problem recurs in 30% to 50% of patients. It may also occur in patients with COPD, asthma, acroidosis, pneumocystis carnii pneumonia and adult respiratory syndrome. Other causes are related to central line placement, thoracentesis, closed lung biopsy or transbronchial lung disruption during biopsy. Symptoms of pneumothorax include sharp, cutting chest pain that surfaces suddenly over the affected area. Older patients often experience dyspnea. Other symptoms include breathlessness, anxiety and cyanosis.5
Pneumonia is an inflammation that affects the parenchyma of the lung, distal to the conducting airways. It involves the respiratory bronchioles and alveolar units. Pneumonia is classified in two categories: community-acquired nosocomial infection or community-acquired pathogen infection. Offending pathogens include Staphylococcus auereus, Klebsiella pneumononiae, Psuedomonas aeruginosa, Enterobacter and Escherichia coli.
The patient with pneumonia presents with chest pain that is usually pleuritic and increases in intensity with movement or cough. Also present are fever, cough, sputum production, dyspnea, dullness to percussion, increased tactile fremitus, late inspiratory crackles and coarse wheezing, bronchophony and egophony. Affected patients have an elevated total white blood count with a shift to the left and hypoxemia.5
Making the distinction between various differential diagnoses for chest pain is a challenge that requires good clinical judgment.6,7 More than half of patients seen in the ED for chest pain and admitted for probable cardiac ischemia turn out not to be affected by this problem. It is easy to confuse cardiac ischemia with other life-threatening illnesses, including pericarditis, aortic dissection and pulmonary embolism.4
The key to a more accurate differential diagnosis of chest pain is a thorough history and physical. Take into account family history and risk factors, as well as the presenting symptoms and physical signs. Test results give more definite answers to help rule out each potential diagnosis. Always begin with a potential diagnosis that carries the most life-threatening risk before proceeding to those with the least risk.
Roxanne Sams is an adult nurse practitioner who is director of emergency, trauma and bayflite services at Bayfront Medical Center in St. Petersburg, Fla. She is also the director of nursing education and event medicine at the hospital. She has master's degrees in nursing and health education.