Chest Pain and Blood Pressure

• Myocardial infarction presents as crushing, substernal pain that may radiate to the left arm or jaw.
• Pericarditis is characterized by chest pain that is relieved when sitting up and leaning forward.
• Aortic dissection involves a sudden, tearing pain radiating to the back.
• Pulmonary embolism presents with sudden pleuritic chest pain and shortness of breath, often in patients with risk factors for deep vein thrombosis.
• Pneumothorax involves sudden, sharp chest pain, accompanied by decreased breath sounds on one side.

Cardiac Risk Factors

• Changeable risk factors:
  • Hypertension
  • Diabetes
  • Hyperlipidemia
  • Smoking
• Non-Changeable risk factors:
  • Family history of heart disease
  • Age
  • Gender

Factors Influencing Blood Pressure

• Blood pressure is directly influenced by:
  • Cardiac output
  • Blood vessel diameter
  • Blood volume

Paramedic Interventions and Blood Pressure Effects

• Normal saline or lactated Ringer’s bolus provides intravascular volume expansion, increasing blood pressure.
• Epinephrine increases vascular resistance and heart rate, leading to a rise in blood pressure.
• Nitroglycerin causes vasodilation, potentially reducing preload and lowering blood pressure.
• Fentanyl, due to vasodilation and reduced pain response, may cause mild hypotension.
• TCP (Transcutaneous Pacing) increases cardiac output, which subsequently raises blood pressure.
• CPAP (Continuous Positive Airway Pressure) can improve oxygenation but might reduce blood pressure by decreasing preload.

Electrical Conduction Sequence in the Heart

• The correct sequence of electrical conduction is: SA node → AV node → Bundle of His → Right and left bundle branches → Purkinje fibers.

Cardiac Terms and Definitions

• Inotropy is the force or strength of myocardial contraction.
• Chronotropy is the rate at which the heart beats.
• Dromotropy is the speed at which electrical impulses travel through the conduction system.
• Automaticity is the ability of a cell to depolarize and generate an action potential without external stimulation.
• All-or-Nothing Response refers to the principle that cardiac muscle fibers either fully contract or not at all once a threshold is reached.