INTRODUCTION Chest pain is the most usual symptom at presentation in patients with acute myocardial infarction (AMI), even if it ishighly subjective, and the pain characteristics, severity and emotional consequences may vary widely.1, 2 An asymptomatic AMI is not necessarily less severe than a symptomatic event. Diabetic and elderly subjects are those who generally present with a lower severity of chest pain and at the same time represent the subgroups of AMI patients withworse outcome.3 Chest pain characteristics over time may also change in relation to the presence and severity of myocardial ischemia whichdepends on several factors influencing the relationship between myocardium at risk oxygen supply and demand. Oxygen supply during the acute …show more content…
At least three receptor subtypes (i.e., μ, κ, and δ) are primarily responsible for the pharmacological effects. The majority of morphine clinical effect has been attributed to the interaction with the μ receptor- which are mainly located in the brain and in the gastro-intestinal tract. The activation of the μ receptors in the brain is responsible for analgesia, sedation, respiratory depression and euphoria. Hypoventilation my favorite ipoxiemia that is definitely an unwanted event in AMI patients. On the other hand, the activation of the opioid receptors widely represented in the myenteric plexus and the intestines may affect the gastro-intestinal tract physiological functions. In particular, morphine delays the transit time from the stomach to the intestine and reduces intestinal and pancreatic secretions. Due to these actions morphine present frequent and relevant gastro-intestinal side effects including constipation, ileus, and occasionally abdominal pain. Moreover, nausea and vomiting are also common side effects of morphine. The vomit mechanism is not well and completely understood; however, the interaction with μ receptors in the chemoreceptor trigger zone and the vomiting center in …show more content…
Thus, the use of morphine could be reserved for patients with pulmonary oedema or persistent severe chest pain after the administration of drugs that favorably alter myocardial oxygen supply and demand while waiting for timely reperfusion. Prospective, randomized, clinical trials are needed to determine whether and how morphine should be administered to patients with chest pain and