Why was the myocardial infarction in my postop patient silent?

Myocardial infarction (MI) in postop patients is in fact usually silent (1,2) but what is less clear is how myocardial ischemia can occur without any symptoms.

Although use of analgesics and narcotics postop may dampen or mask chest pain or other symptoms associated with MI, other factors are also likely to play an important role, such as decreased sensitivity to painful stimuli, autonomic neuropathy (eg, in diabetes mellitus), and higher pain threshold among some patients (3).

Additional factors associated with silent MIs include cerebral cortical dysfunction since frontal cortical activation appears to be necessary to experience cardiac pain. Mental stress is also a frequent trigger for asymptomatic myocardial ischemia, infarction and sudden cardiac death (4).  High levels of beta-endorphin, an endogenous opiate, may also play a role (5).

 
Perhaps the most intriguing explanation for lack of symptoms is the observation that the levels of anti-inflammatory cytokines (interleukin-4 and -10)—which block pain transmission pathways and increase the threshold for nerve activation—seem to be increased in patients with silent myocardial ischemia (6).  Even more relevant to our postop patient is the finding that interleukin-10 production increases during and after major abdominal surgery and correlates with the amount of intraoperative blood loss (7). 

No wonder MIs in postop patients are often silent!

References
1. Devereaux PJ, Xavier D, Pogue J, et al. Characteristics nd short-term prognosis of perioperative myocardial infarction in patients undergoing noncardiac surgery: a cohort study. Ann Intern Med 2011;154:523-8. https://annals.org/aim/article-abstract/746934/characteristics-short-term-prognosis-perioperative-myocardial-infarction-patients-undergoing-noncardiac 
2. Badner NH, Knill RL, Brown JE, et al. Myocardial infarction after noncardiac surgery. Anesthesiology 1998;88:572-78. http://anesthesiology.pubs.asahq.org/article.aspx?articleid=1948483
3. Ahmed AH, Shankar KJ, Eftekhari H, et al. Silent myocardial ischemia:current perspectives and future directions. Exp Clin Cardiol 2007;12:189-96. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2359606/ 
4. Gullette EC, Blumenthal JA, Babyak M, et al. Effects of mental stress on myocardial ischemia during daily life. JAMA 1997;277:1521-6. https://jama.jamanetwork.com/journals/jama/articlepdf/416233/jama_277_19_029.pdf
5. Hikita H, Kurita A, Takase B, et al. Re-examination of the roles of beta-endorphin and cardiac autonomic function in exercise-induced silent myocardial ischemia. Ann Noninvasive Electrocardiol 1997;2:319-25. https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1542-474X.1997.tb00195.x
6. Mazzone A, Cusa C, Mazzucchelli I, et al. Increased production of inflammatory cytokines in patients with silent myocardial ischemia. J Am Coll Cardiol 2001;38:1895-901. https://www.ncbi.nlm.nih.gov/pubmed/11738291
7. Kato M, Honda I, Suzuki H, et al. Interleukin-10 production during and after upper abdominal surgery. J Clin Anesth 1998;10:184-8. https://www.ncbi.nlm.nih.gov/pubmed/9603586 

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Why was the myocardial infarction in my postop patient silent?

My patient with angina symptoms also complains of neck pain with left arm numbness. Could they be related?

Short answer, yes! Anterior chest pain associated with cervical intervertebral disk disease, ossified posterior longitudinal ligament or other spinal disorders is sometimes referred to as “cervical angina” (CA) or “pseudoangina” and is an often overlooked source of non-cardiac chest pain. 1-5

Although its exact prevalence is unknown, 1.4% to 16% of patients undergoing cervical disk surgery may have symptoms of CA. 1 Conversely, 1 study reported 5% of patients with angina pectoris having cervical nerve root pathology.5 Many patients describe their chest pain as “pressure” or crushing in quality mimicking typical cardiac ischemia chest pain, often resulting in extensive cardiac workup.  To add to the confusion, some patients even respond to nitroglycerin! One-half of patients also experience autonomic symptoms such as dyspnea, vertigo, nausea, diaphoresis, pallor, fatigue, and diploplia.1

Certain clues in the patient’s presentation should help us seriously consider the possibility of CA: 1-3

  • History of cervical radiculopathy eg, subjective upper extremity weakness or sensory changes, occipital headache or neck pain
  • Pain induced by cervical range of motion or movement of upper extremity
  • History of cervical injury or recent manual labor (eg, lifting, pulling or pushing)
  • Pain lasting greater than 30 min or less than 5 seconds and not relieved by rest
  • Positive Spurling maneuver ie, reproduction of symptoms by rotating the cervical spine toward the symptomatic side while providing a downward compression through the patient’s head

CA is often attributed to cervical nerve root compression, likely mediated by compression of C4-C8 nerve roots which also supply the sensory and motor innervation of the anterior chest wall.

Bonus Pearl: Did you know that experimental stimulation of spinothalamic tract cells in the upper thoracic and lower cervical segments have been shown to reproduce angina pain? 6

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References

  1. Susman WI, Makovitch SA, Merchant SHI, et al. Cervical angina: an overlooked source of noncardiac chest pain. The Neurohospitalist 2015;5:22-27. https://www.ncbi.nlm.nih.gov/pubmed/25553225
  2. Jacobs B. Cervical angina. NY State J Med 1990;90:8-11. https://www.ncbi.nlm.nih.gov/pubmed/2296405
  3. Sheps DS, Creed F, Clouse RE. Chest pain in patients with cardiac and noncardiac disease. Psychosomatic Medicine 66:861-67. https://www.ncbi.nlm.nih.gov/pubmed/15564350
  4. Wells P. Cervical angina. Am Fam Physician 1997;55:2262-4. https://www.ncbi.nlm.nih.gov/pubmed/9149653
  5. Nakajima H, Uchida K, Kobayashi S, et al. Cervical angina: a seemingly still neglected symptom of cervical spine disorder. Spinal Cord 2006;44:509-513. https://www.ncbi.nlm.nih.gov/pubmed/16331305
  6.  Cheshire WP. Spinal cord infarction mimicking angina pectoris. Mayo Clin Proc 2000;75:1197-99. https://www.ncbi.nlm.nih.gov/pubmed/11075751

 

My patient with angina symptoms also complains of neck pain with left arm numbness. Could they be related?