Chest Pain: Causes

• Inotropy refers to the strength of cardiac muscle contraction.
• Chronotropy refers to heart rate.
• Dromotropy refers to the rate of nervous impulse conduction.
• The heart uniquely generates its own electrical impulses.
• Individual heart cells can depolarize spontaneously, termed self-excitation.
• The cell with the fastest discharge rate, or automaticity, serves as the heart’s pacemaker.

Cardiovascular Causes of Chest Pain

• Cardiac ischemia
• Pericarditis (viral or autoimmune)
• Aortic dissection

Respiratory Causes of Chest Pain

• Pulmonary embolism
• Pneumothorax
• Pneumonia
• Pleurisy (pleural irritation)

Gastrointestinal Causes of Chest Pain

• Cholecystitis
• Pancreatitis
• Hiatal hernia
• Esophageal disease
• Gastroesophageal reflux disease (GERD)
• Peptic ulcer disease
• Dyspepsia

Musculoskeletal Causes of Chest Pain

• Chest wall syndrome
• Costochondritis
• Acromioclavicular disease
• Herpes zoster (shingles)
• Chest wall trauma
• Chest wall tumors

General Signs/Symptoms

• Discomfort, dyspnea, cough, syncope, palpitation, ALOC (altered level of consciousness), diaphoresis, restlessness and anxiety, feeling of impending doom, nausea/vomiting, fatigue, edema, headache, anguished facial expression, activity limitations, and trauma.
• Diabetic patients with myocardial injury might not experience chest pain.

Factors Increasing Risk of Cardiac Issues

• Smoking and cocaine use, older age, family history of cardiac disease, hypertension, hypercholesterolemia, carbohydrate intolerance, male gender, lack of exercise, diet, obesity, oral contraceptives, Type A personalities, and psychosocial tensions (stress).

Out-of-Hospital Treatment Modalities

• Point of care testing (POC), IV and fluids, medications (aspirin, nitro, fentanyl, O2)
• Medications for accompanying heart rates and rhythms (adenosine, lidocaine)
• Other therapies include prescribed medications, and lifestyle changes

Electrical Conduction System of the Heart

• The sinoatrial (SA) node is the heart's primary pacemaker.
• The SA node's intrinsic rate is 60-100 bpm.
• The interatrial pathway from the SA node allows left atrium contraction.
• The internodal pathway connects electrical junctions.
• The atrioventricular (AV) junction delays signals, allowing full atrial depolarization and contraction.
• The AV junction serves as a backup pacemaker with an intrinsic rate of 40-60 bpm.
• Signals travel from the AV junction to the Bundle of His, splitting into left and right bundle branches, ending at the Purkinje fibers.
• Purkinje fibers contract the ventricles and act as a last backup pacemaker with an intrinsic rate of 20-40 bpm.
• Irritability occurs when a lower site takes over as pacemaker.
• The escape mechanism engages when a lower pacemaker site takes over due to the failure of the normal pacemaker.

Pericarditis

• Pericarditis is the inflammation of the pericardium, resulting in swelling and irritation.
• It's normally caused when the linings of the walls rub against each other, causing a sharp or stabbing pain.
• Heart attacks or heart surgeries can be causes.

Overview of cardiovascular, respiratory, gastrointestinal, and musculoskeletal causes of chest pain. Also, the heart generates its own electrical impulses. Cardiac ischemia is a common cause.