EMS 82 Week 1 quiz prep

• Inotropy refers to the strength of cardiac muscle contraction.
  • A positive inotropic agent strengthens cardiac contraction.
  • A negative inotropic agent weakens cardiac contraction.
• Chronotropy refers to heart rate.
  • A positive chronotropic agent increases heart rate.
  • A negative chronotropic agent decreases heart rate.
• Dromotropy refers to the rate of nervous impulse conduction.
  • A positive dromotropic agent speeds impulse conduction.
  • A negative dromotropic agent slows down conduction.
• The heart uniquely creates its own electrical impulse through self-excitation of individual cells.
• The cell with the fastest rate of discharge or automaticity in the cardiac system is the heart’s pacemaker, exhibiting the fastest rate of automaticity.

Cardiovascular Causes of Signs/Symptoms

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

Respiratory Causes of Signs/Symptoms

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

Gastrointestinal Causes of Signs/Symptoms

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

Musculoskeletal Causes of Signs/Symptoms

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

Common Signs and Symptoms

• Discomfort
• Dyspnea
• Cough
• Syncope
• Palpitation
• Altered Level of Consciousness (ALOC)
• Diaphoresis
• Restlessness and anxiety
• Feeling of impending doom
• Nausea/vomiting
• Fatigue
• Edema
• Headache
• Anguished facial expression
• Activity limitations
• Trauma
• Diabetic patients with myocardial injury may not experience chest pain

Risk Factors

• Smoking and cocaine use
• Older age
• Family history of cardiac disease
• Hypertension
• Hypercholesterolemia
• Carbohydrate intolerance
• Male gender
• Lack of exercise
• Diet
• Obesity
• Oral contraceptives (birth control)
• Type A personalities
• Psychosocial tensions (stress)

Out of Hospital Treatment

• Point of care testing (POC)
• IV and fluids
• Medications: aspirin, nitro, fentanyl, O2
• Medications for heart rate and rhythm: adenosine, lidocaine
• Other therapies: prescribed medications, lifestyle changes

Cardiac Electrical Conduction

SA Node

• The sinoatrial (SA) node is the primary pacemaker, initiating the electrical impulse.
• Two pathways originate from here, the interatrial pathway and the internodal pathway.
• The interatrial pathway leads to the left atrium, facilitating its contraction.
• The internodal pathway connects the electrical junctions.
• The SA node's intrinsic rate is 60-100 bpm

AV Junction

• Signals pass to the atrioventricular (AV) junction, delaying signal and allowing atria to fully depolarize and contract blood into ventricles.
• The AV junction serves as the secondary pacemaker and escape mechanism.
• The intrinsic rate of the AV junction is 40-60 bpm.

Bundle of His and Purkinje Fibers

• Signals travel to the Bundle of His, splitting into the left and right bundle branches, ending at the Purkinje fibers.
• These fibers contract the ventricles, acting as the last backup pacemaker.
• The intrinsic rate of the Purkinje fibers is 20-40 bpm.

Irritability and Escape Mechanism

• Irritability occurs when a lower site on the pathway takes over as the pacemaker.
• The escape mechanism activates when a lower pacemaker site takes over due to failure of the normal pacemaker.

Pericarditis

• Pericarditis is an inflammation of the pericardium, that results in swelling and irritation of the thin membranous sac that surrounds the heart.
• It is normally caused when the linings of the walls rub against each other, causing a sharp or stabbing pain.
• Heart attacks or heart surgeries can also cause this.

Inotropy changes contraction strength, chronotropy affects heart rate, and dromotropy impacts nerve impulse speed. The heart generates electrical impulses through self-excitation. Cardiovascular and respiratory issues can cause related signs/symptoms.