Sunday, April 4, 2021

Chest Pain, Undifferentiated Case File

Posted By: Medical Group - 4/04/2021 Post Author : Medical Group Post Date : Sunday, April 4, 2021 Post Time : 4/04/2021
Chest Pain, Undifferentiated Case File
Eugene C. Toy, Md, Michael d . Faulx, Md

Case 21
A 68-year-old obese man is brought in by ambulance to the emergency room com plaining of abrupt onset of chest discomfort for the past hour. He describes “severe aching” under the distal aspect of his sternum with radiation into the inferior left side of his chest. His symptoms started at rest, have been constant, and worsen when he takes a deep breath. He has a history of acid reflux disease, alcoholism, hyperlipidemia, hypertension, prostate cancer, and a strong family history of early myocardial infarction. On examination, the patient appears restless and in modest distress. Vital signs are temperature 98.4°F, heart rate 112 bpm, blood pressure 82/54 mmHg in the left arm and 84/57 mmHg in the right arm, respirations 26 breaths/min, and oxygen saturation 90% on room air. The patient’s breathing is labored, with normal breath sounds. He has a tachycardic, regular rhythm with out murmurs, rubs, or gallops. The epigastrium is mildly tender to palpation, and his stool is guiac-negative.
  • What are the priority diagnosis to evaluate?
  • What are your next diagnostic steps?

Answer to Case 21:
Chest Pain, Undifferentiated

Summary: This 68-year-old man presents with vague substernal and left-sided chest pain for 1 hour. His pain is associated with dyspnea, tachypnea, and unstable vital signs, including hypotension, tachycardia, and relative hypoxia. He is currently in respiratory distress, and triage should focus on differentiating between possible life threatening etiologies of his symptoms that require urgent attention.
  • Priority differential diagnosis: “Can’t miss” diagnoses include pulmonary embolism (PE), acute coronary syndrome (ACS), aortic dissection, and tension pneumothorax, since these are potentially fatal conditions.
  • Next diagnostic steps: Stat ECG, CXR, labs (including cardiac biomarkers and ABG), and consider contrast enhanced CT of the chest.

ANALYSIS

Objectives
  1. Understand the differential diagnosis and triage of chest pain, and be able to rule out life-threatening emergent causes (acute myocardial infarction, pulmonary embolism, pneumothorax, and aortic dissection).
  2. Be able to distinguish angina from other types of chest pain.
  3. Identify the treatment options available for common causes of chest pain.
Considerations
Undifferentiated chest pain in the emergency medical setting is an extremely common presentation. In all patients with undifferentiated chest pain, the initial priority should be ruling out life-threatening causes, as prompt intervention may prove life-saving. Subtle changes in vital signs (such as tachycardia and mild hypoxia) should be noted; although nonspecific, this may be the first clue of a serious underlying etiology. This patient has risk factors for thromboembolic disease (obesity and malignancy), cardiovascular disease (obesity, age, gender, hypertension, hyperlipidemia, and a strong family history), as well as peptic ulcer disease (acid reflux and alcoholism). As such, the differential should initially be kept broad, and narrowed once life- threatening causes are ruled out.

Approach To:
Chest Pain

DEFINITIONS

ACUTE CORONARY SYNDROME (ACS): Consisting of unstable angina, non-ST elevation MI (NSTEMI), and ST elevation MI.

AORTIC DISSECTION: Intimal tear of the aorta with blood tracking within the media of the ascending (type A) or descending (type B) aorta, creating a false lumen.

PERCUTANEOUS CORONARY INTERVENTION (PCI): Catheter-based therapy by blood flow is returned to an occluded coronary artery by balloon angioplasty or stenting.

PNEUMOTHORAX: Occupation of the pleural space by air, often due to trauma, rupture of a pleural bleb, or iatrogenesis. May be simple (uncomplicated), or tension, with shifting of the mediastinum, respiratory distress, and hemodynamic compromise.

THROMBOLYSIS: Restoration of blood flow to the coronary or pulmonary vasculature by administration of thrombolytic agents, which activate plasmin, promoting fibrinolysis.

Differential Diagnosis
The differential diagnosis of chest pain is extensive, and although it is usually due to benign causes, some causes of chest pain may be life-threatening. As such, for each patient presenting with chest pain, serious causes should be ruled out before less dangerous conditions are considered. Common etiologies of chest pain grouped by system are summarized in Table 21-1.

The differential diagnosis should be tailored to individual patients according to their presentation, specific risk factor profile, and setting in which they are evaluated. Nonemergent chest pain evaluated in the primary care office is most often due to musculoskeletal pain followed by gastrointestinal issues and is less commonly due to cardiac causes (most of which are stable angina). However, even in the primary care office, patients with risk factors for coronary artery disease are much more likely to have cardiac pain, and in patients older than 40, up to 50% of cases of acute chest pain may be due to a cardiac cause. Further, in the emergency department (ED), the likelihood of a life-threatening cause of chest pain is much greater, and as such the index of suspicion for such causes should be higher in patients seen in the ED.

History
Several important clues to be gained from the patient history can help rule in or out potentially fatal causes of chest pain. The duration of the chest pain is of specific

common causes of chest pain by organ system

Abbreviations: ACS, acute coronary syndrome; d ES, diffuse esophageal spasm; g Er d , gastroesophageal reflux disease; MSK, musculoskeletal; NSTEMI, non-ST elevation MI; PUd , peptic ulcer disease; STEMI, ST elevation MI.
*Indicates potentially life-threatening diagnosis.

importance, as MI, pneumothorax, PE, and aortic dissection typically have an abrupt onset and may last for hours, but are rarely present for days on end. Further, it is crucial to determine whether the pain is exertional, occurs at rest, is pleuritic, is positional, or is similar to pain in any prior episodes. Additionally, the quality of the pain, location, and radiation are important. Although myocardial ischemia classically localizes to the midchest or left chest and often radiates to the left jaw and down the left arm, presentations may be atypical in the elderly, women, and diabetics. Up to one-third of these patients may not experience classic ischemic chest pain with myocardial infarction (MI). Further, the pain of an aortic dissection is typically severe and “tearing,” radiating from the chest through to the back. Pulmonary embolus classically causes pleuritic pain (which worsens on deep inhalation), and is more common in patients with malignancy, on oral contraceptive pills, in hypercoagulable states (Factor V Leiden, oral contraceptive pills, etc), and following recent travel (eg, a long plane flight or car ride). Spontaneous pneumothorax classically occurs in tall patients, those with cystic fibrosis, α1-antitrypsin deficiency, following trauma to the chest, or iatrogenically.

Certain characteristics increase the likelihood of chest pain that is attributable to myocardial ischemia, including pain that radiates to either arm or shoulder, exertional pain, pain associated with diaphoresis, and pain similar to or worse than pain during a prior MI. Findings that decrease the likelihood that the chest pain is due to a myocardial ischemia include pain that is pleuritic, positional, sharp, focal, or reproducible with palpation.

Less urgent causes of chest pain that may mimic MI include the following (see also Table 21-1): pericarditis (pain is typically better when leaning forward, and may be pleuritic), myocarditis (may be preceded by a recent flulike illness), pneumonia (may be associated with fevers, chills, cough, and leukocytosis), peptic ulcer (pain is more epigastric, is reproducible, and may be associated with peritoneal signs if perforated), pancreatitis, cholecystitis, and musculoskeletal pain (always a diagnosis of exclusion).

Physical Exam
Assessment of the vital signs is essential in the early evaluation of chest pain. Tachycardia and tachypnea may be early signs of a pulmonary embolism, even if the patient is not hypoxic. Additionally, while not very sensitive, a blood pressure differential of >20 mmHg between the arms is suggestive of an aortic dissection.

The physical examination may otherwise be completely normal in a patient with life-threatening chest pain. As such, a normal exam may be falsely assuring, and diagnostic testing should be pursued. However, patients with an MI may develop a 4th heart sound, and may have an audible murmur of ischemic mitral regurgitation or signs of heart failure on examination. Patients with a pneumothorax may exhibit decreased breath sounds or hemodynamic instability, an important clue to this diagnosis.

Diagnostic Testing
An ECG should be obtained within 10 minutes of arrival to the ED to rule out acute MI. Evidence of right-heart strain may be apparent on ECG in patients presenting with PE, but this is not a uniform finding. A portable CXR should be obtained as soon as able if pneumothorax is suspected; this will also help rule out respiratory causes of chest pain, such as pneumonia. Labs, including cardiac biomarkers
[troponin, creatine kinase myocardial band (CK-MB)], creatinine, platelet count, coagulation factors (prothrombin and activated thromboplastin time), and blood type should be obtained in case anticoagulation is needed. Further, a d -dimer may be ordered for patients at low to intermediate risk of PE, and a CT angiogram should be considered in patients for whom PE or aortic dissection is suspected. d -dimer has outstanding negative predictive value in the assessment of patients with suspected PE or aortic dissection; a completely normal d -dimer virtually excludes these diagnoses from the differential. Additional diagnostic testing should be individualized to each patient’s needs (liver function tests, amylase/lipase, etc).

Findings on ECG suggestive of an acute MI include ST segment depression and T wave inversion in the setting of an NSTEMI, and ST segment elevation or new left bundle branch block due to a STEMI. If ECG is equivocal or the diagnosis is in question and the patient is stable, a bedside transthoracic echocardiogram should be performed to rule out regional wall motion abnormalities due to cardiac ischemia.

Emergent Therapy
Emergent therapy for patients for chest pain may be lifesaving and should be directed at the underlying cause. Patients with an acute MI should be given a full-dose aspirin (325 mg), and started on IV unfractionated heparin, and administration of a potent platelet inhibitor (such as clopidogrel, prasugrel, or ticagrelor) should be considered in patients without contraindications. Patients with STEMI should immediately proceed to PCI, and patients with STEMI who cannot receive PCI within 120 minutes should be considered for thrombolysis (with an agent such as alteplase, reteplace, or tenekteplase), whereas lytic agents are contraindicated in NSTEMI. For NSTEMI, if not high-risk, PCI can be delayed for up to 72 hours, and patients with high-risk NSTEMI (persistent chest pain, heart failure, or electrical instability) should proceed immediately to PCI. Efforts should also be made to control pain (with IV nitroglycerin or morphine if refractory), and myocardial oxygen demand (with IV nitroglycerine, beta-blocker, ACE inhibitor, or other therapy). See Cases 1 and 2 for additional information regarding the management of patients with acute coronary syndromes. It is essential to determine whether the chest pain may be due to aortic dissection or MI, as antiplatelet and anticoagulant agents are contraindicated in patients with aortic dissection but standard of care with MI. Patients with aortic dissection are typically emergently treated with IV beta-blockers (which decrease heart rate, blood pressure, and shear force of blood along the arterial wall) and afterload reduction with nitroprusside. Type A dissections (involving the ascending aorta to the left subclavian artery) are typically managed with immediate surgery, whereas type B dissections (involving the descending aorta distal to the left subclavian artery) may be initially managed medically with surgery reserved for patients with refractory pain or evidence of end-organ hypoperfusion.

In the case of simple, uncomplicated pneumothorax, patients are typically monitored closely with serial CXR, and 100% oxygen may be empirically administered to increase the rate of absorption. Patients with tension pneumothorax are often unstable on presentation, and require a needle thoracotomy to the 2nd intercostal space, midclavicular line. This immediately relieves the pressure, and a chest tube may be placed surgically immediately thereafter.

CASE CORRELATION
  • See also Case 1 (acute coronary syndrome/STEMI), Case 2 (acute coronary syndrome/NSTEMI), Case 4 (chronic coronary artery disease), Case 8 (hypertrophic obstructive cardiomyopathy), and Case 10 (valvular stenosis).

COMPREHENSION QUESTIONS

21.1 A 68-year-old man with no medical history presents to a rural emergency department with chest pain for the past 30 minutes. The ECG shows ST elevation in V3–V6 and I, and aVL. The hospital is not equipped for PCI, and the closest hospital that performs PCI is 3 hours away. Vital signs are HR 110 bpm, BP 150/84 mmHg, RR 18 per minute, and O2 saturation 98% on room air (RA). In addition to aspirin and IV heparin, what is the most appropriate next step?
A. Administration of full-dose thrombolysis, and transfer to the nearest PCI capable hospital for angiography
B. Administration of full-dose thrombolysis, and subsequent transfer only if patient is unstable
C. Administration of half-dose thrombolysis, and transfer to the nearest PCI capable hospital for immediate PCI
D. Medical management with the addition of clopidogrel

21.2 A 70-year-old woman with a history of hypertension, coronary artery disease, and smoking presents with tearing chest pain across the chest that radiates to the back for the past 1 hour. Vitals are HR 100 bpm , BP 190/110 mmHg, RR 18 per minute, and O2 saturation 97% on RA. A chest CT with contrast shows an aortic dissection extending 1 cm distal to the left subclavian artery to 2 cm superior to the renal arteries. What is the most appropriate management strategy?
A. Immediate surgery
B. Administration of IV labetalol, nitroglycerine, and surgery when stable
C. Administration of IV heparin, IV metoprolol, and continued monitoring
D. Administration of IV heparin, IV nitroprusside, IV metoprolol, and continued monitoring
E. Administration of IV metoprolol, IV nitroprusside, and continued monitoring

21.3 An 18-year-old man presents with chest pain and dyspnea with deep breathing for the past 1 hour. Vitals are stable. CXR shows a small pneumothorax involving 10% of area of the left lung. What is the most appropriate management strategy?
A. Needle thoracotomy of the L 2nd intercostal space, midclavicular line
B. Placement of a chest tube
C. 100% oxygen and serial CXR over the next 24 hours
D. Albuterol inhaler, 100% oxygen, and chest physical therapy

21.4 A 45-year-old man with a history of hypertension and lung cancer presents with pleuritic chest pain, and left calf swelling after a 4-hour plane flight. He is tachycardic, hypoxic, but otherwise stable. What is the most appropriate next step in management?
A. Obtain a left lower extremity venous ultrasound
B. Obtain a chest CT scan with contrast
C. Obtain a bedside transthoracic echocardiogram
D. Check a d -dimer
E. Empiric administration of IV unfractionated heparin


ANSWERS

21.1 A. Patients who present to a hospital not equipped for PCI who are more than 120 minutes from the nearest PCI-capable hospital should be given thrombolysis unless contraindicated. Angiography can then be performed, and PCI carried out if reperfusion is not complete. Trials of half-dose lytic and immediate PCI (called “facilitated PCI”) have not shown favorable results, and this strategy is not advocated.

21.2 E. This patient has a type B aortic dissection, which may be managed medically with IV metoprolol and IV nitroprusside. Intravenous labetalol does not reduce shear force of blood along the arterial wall as well as metoprolol, and nitroglycerine is generally considered inferior to nitroprusside for afterload reduction. Surgery is not required unless the aneurysm continues to extend or there are complications, and IV heparin is contraindicated.

21.3 C. This young man has a simple, uncomplicated pneumothorax, which may be monitored with serial CXR for stability. No urgent intervention is required, and 100% oxygen may help it resorb. Needle thoracotomy and chest tube are therapies reserved for tension pneumothorax.

21.4 B. This patient likely has a pulmonary embolism, caused by a left lower extremity deep-vein thrombosis (DVT). The next best step is to obtain a chest CT with contrast to confirm the diagnosis. In patients with renal insufficiency, a venous ultrasound to confirm a DVT may be sufficient to infer a diagnosis, but is less ideal. A bedside echocardiogram is typically unnecessary unless the right heart needs to be assessed in a patient with signs of hemodynamic instability. A d-dimer is reasonable to rule out a PE in a patient with low to intermediate probability for PE; however, this may be falsely elevated in this patient with lung cancer. IV heparin should not be administered without a diagnosis if this can be avoided.


CLINICAL PEARLS
  • The evaluation of chest pain should be tailored to individual patients, considering their history and the setting in which they are evaluated.
  • "Can’t miss" potentially life-threatening diagnoses include acute myocardial infarction, aortic dissection, tension pneumothorax, and pulmonary embolism.
  • An ECG should be done within 10 minutes of arrival to the Ed to rule out an acute MI.
  • A blood pressure differential of>20 mmHg in both arms is suggestive of an aortic dissection, and a CT angiogram should be urgently ordered to exclude this diagnosis.
  • The treatment for STEMI is immediate revascularization with PCI or thrombolysis. NSTEMI may be managed with a delayed invasive strategy of PCI within 72 hours and should not be given thrombolytics.
References

Hagan PG, Nienaber CA, Isselbacher EM, et al. The International Registry of Acute Aortic Dissection (IRAD): new insights into an old disease. JAMA. 2000;283:897–903. 

Klinkman MS, Stevens D, Gorenflo DW. Episodes of care for chest pain: a preliminary report from MIRNET. Michigan Research Network. J Fam Pract. 1994;38:345. 

Panju AA, Hemmelgarn BR, Guyatt GH, et al. The rational clinical examination. Is this patient having a myocardial infarction? JAMA. 1998;280:1256–1263. 

Sahn SA, Heffner JE. Spontaneous pneumothorax. N Engl J Med. 2000:342:868–874. 

Swap CJ, Nagurney JT. Value and limitations of chest pain history in the evaluation of patients with suspected acute coronary syndromes. JAMA. 2005;294:2623–2629.

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