Heart Anatomy and Cardiac Function Review

Overview of Heart Function

• The heart operates as a pump, requiring both mechanical movement and electrical signals.
• Key structures in heart function include the SA node, AV node, bundle of His, and Purkinje fibers.

Electrical Conductivity of the Heart

• SA Node: Located at the top of the right atrium; initiates electrical impulses and starts the heartbeat.
• AV Node: Receives electrical signals from the SA node and relays them to the ventricles.
• Bundle of His and Purkinje Fibers: Conduct electrical signals to the ventricles, causing them to contract.
• The heart's rhythm can be monitored using an ECG (electrocardiogram).

Conditions Observed in Cardiac Monitoring

• Atrial Fibrillation (A-Fib): Irregular and rapid heart rate caused by intermittent firing of electrical impulses. Patients often require blood thinner medications due to clot risk.
• Ventricular Fibrillation (V-Fib): Chaotic electrical activity leading to inefficient heart pumping; requires immediate defibrillation.
• Tachycardia and Bradycardia: Defined as heart rates greater than 100 bpm and less than 60 bpm, respectively.

Heart Murmurs and Blockages

• Murmurs: Abnormal heart sounds; may indicate structural heart issues.
• Bundle Branch Blocks: Blockage in the heart's electrical conduction system categorized into right and left blocks, with left blocks often indicating significant heart issues.

Cardiac Output and Stroke Volume

• Cardiac Output: Defined as the amount of blood the heart pumps in a minute.
  • Formula: $ext{Cardiac Output} = ext{Stroke Volume} imes ext{Heart Rate}$
  • Average stroke volume is approximately 70-100 mL per heartbeat.
• Blood pressure and heart rate are essential indicators of cardiovascular health.

Coronary Arteries

• The left coronary artery (often referred to as the "widowmaker") supplies the majority of blood to the heart.
• The right coronary artery supplies lesser portions and is involved in supplying the right side of the heart.

Risk Factors for Myocardial Infarction (Heart Attack)

• Controllable Factors: High blood pressure, smoking, high cholesterol, diabetes, lack of exercise, obesity.
• Uncontrollable Factors: Age, family history, previous heart issues.

Angina and Heart Attack

• Stable Angina: Predictable, triggered by exertion, relieves with rest.
• Unstable Angina: Occurs unexpectedly, lasts longer, and may not respond to treatment, indicating a high risk for a heart attack.

Symptoms of Heart Attack

• Common symptoms include:
  • Chest pain or discomfort
  • Pain radiating to the back, shoulders, arms, or stomach
  • Shortness of breath
  • Dizziness or light-headedness
  • Sweating and nausea

Treatment Protocols for Cardiac Events

• Immediate treatment priorities include administering aspirin and oxygen, monitoring vitals, and preparing for potential defibrillation.
• In cases of severe ischemia, thrombolytic therapy may be utilized to dissolve clots.

Cardiac Dysrhythmias

• Ventricular Tachycardia (VTAC): Fast heart rhythm originating from the ventricles; can be life-threatening.
• Asystole: No electrical activity in the heart, indicating a critical situation requiring immediate CPR.

Emergency Response for Cardiac Arrest

• Importance of timely defibrillation in cases of V-Fib and PEA (pulseless electrical activity).
• Survival rates significantly decline for every minute without defibrillation; thus early initiation of CPR and use of an AED is vital.

Pulmonary Issues Related to Cardiac Events

• Pulmonary Edema: Caused by fluid backing up due to poor heart function, may present with crackling lung sounds.

Prevalence of Conditions Due to Lifestyle Choices

• Increased risk in certain demographics, including those with sedentary lifestyles, poor diets, and chronic health issues such as diabetes or hypertension.

Conclusion

• Continuous education about heart health, monitoring vital signs, and understanding symptoms of cardiac distress are crucial for effective emergency response and patient safety.