Ventricular septal defect

Disease Description (Causes and Symptoms)

• Definition and pathophysiology: Ventricular fibrillation (VF) is a condition in which the ventricles contract extremely rapidly (approximately 350–600 times per minute) and chaotically, resulting in the loss of effective cardiac output. The electrical activation of the ventricles becomes disorganized, preventing blood ejection and potentially progressing immediately to circulatory failure and pulseless electrical activity, resulting in death. It is common as a primary cause in the early phase of acute myocardial infarction, and the prognosis worsens rapidly if defibrillation is delayed early after onset.
• Main causes: Coronary artery disease (including acute myocardial infarction), cardiomyopathy, heart failure, cardiac surgery, pericarditis, thyrotoxicosis, hypertensive heart disease, rheumatic valvular disease, excessive alcohol consumption, and others. It can occur due to electrophysiological abnormalities even in the absence of structural heart disease.
• Symptoms: Sudden loss of consciousness (syncope), a pulseless state, shortness of breath or cessation of breathing, chest pain or palpitations (immediately before the episode). When VF occurs, the pulse cannot be palpated immediately.
• Diagnostic findings: The ECG shows coarse or fine, chaotic waveforms (unlike flutter, there is no regular periodicity). In the field, VF is suspected based on loss of consciousness and a pulse.
• Clinical features: The incidence is high within the first 4 hours after acute myocardial infarction (reported at approximately 3–5%). It is fatal without immediate defibrillation.

Treatment

• Emergency treatment (the most important measures)
  • Immediate defibrillation (unsynchronized electrical shock) — defibrillation is the highest-priority treatment for VF.
  • If a defibrillator is not ready, start cardiopulmonary resuscitation (CPR) immediately to maintain cerebral and cardiac perfusion.
• Summary of ACLS (advanced cardiovascular life support) guidelines
  • Attempt defibrillation together with CPR (if possible, use rapid, high-energy monophasic defibrillation).
  • For VF without ROSC (return of spontaneous circulation) after defibrillation or for recurrent VF, consider intravenous epinephrine (adrenaline) every 3–5 minutes and an antiarrhythmic agent (IV amiodarone recommended, or lidocaine).
  • Identify and treat the cause: if acute ischemia is suspected, prioritize reperfusion treatment such as percutaneous coronary intervention (PCI).
• Intensive care after resuscitation (after ROSC)
  • Secure the airway, provide ventilation/oxygenation, and monitor hemodynamics.
  • Consider targeted temperature management (temperature control to improve neurological prognosis).
  • Correct electrolyte abnormalities (potassium and magnesium), metabolic acidosis, hypothermia, hypoglycemia, and other abnormalities.
  • Correct the cause (e.g., address the Hs and Ts, including pleural pressure-related conditions, tension pneumothorax, cardiac tamponade, and drug poisoning).
• Long-term management and prevention
  • If the cause cannot be corrected or the risk of recurrence is high, consider an implantable cardioverter-defibrillator (ICD) for primary or secondary prevention.
  • Optimize treatment of underlying conditions (such as coronary artery disease and cardiomyopathy) (reperfusion and medications: beta-blockers, ACE inhibitors/ARBs, antiarrhythmic agents, etc.).
  • Lifestyle management: Avoid excessive alcohol consumption, prevent electrolyte imbalance, and check prescribed medications and contraindicated medications.
• Precautions and risk of complications
  • Immediate defibrillation is the key to successful treatment; the risk of brain damage and death rises sharply when defibrillation is delayed.
  • Rib fractures and chest injuries may occur due to chest compressions and defibrillation during resuscitation.
  • Neurological morbidity, kidney injury, infection, and recurrent arrhythmias may occur after resuscitation.
• Hs and Ts to remember in an emergency (checking for treatable causes)
  • Hypoxia, Hypovolemia, Hydrogen ion(acidosis), Hypo/Hyperkalemia, Hypothermia, Tension pneumothorax, Tamponade (cardiac), Toxins, Thrombosis (pulmonary or coronary)

Checklist Before an Outpatient Visit (Including Sample Questions)

• Items and documents to prepare
  • A list of currently taken medications (including prescription drugs, OTC medications, nutritional supplements, and supplements)
  • Previous ECGs, echocardiograms (Echo), coronary angiography (PCI/CAG) reports, and test results
  • History of previous surgeries (including cardiac surgery) and whether an implanted device (ICD or pacemaker) is present
  • The time and circumstances of recent symptom onset (e.g., activity at the time of syncope and preceding symptoms), and history of CPR or defibrillation
  • Family history (sudden death or hereditary heart disease)
• Items to record before the outpatient visit (in sample-question format)
  • When did the symptoms first begin, and how frequently did they occur?
  • Did you experience syncope or loss of consciousness? What measures were taken by people nearby at the time?
  • Do you have any pre-existing heart disease, diabetes, hypertension, or thyroid disease?
  • Do you have any allergies or a history of adverse reactions to specific medications?

Examples of General Questions to Ask the Doctor

• What are the main side effects and precautions of this medication (or treatment)?
• What is the suspected cause of this event, and what is the prognosis (survival rate and neurological recovery)?
• When can I resume daily activities (driving, work, and exercise)? What restrictions will apply?

Examples of Condition-Specific Questions

• Do I need an ICD (implantable cardioverter-defibrillator) in my case? What are the indications and long-term management requirements?
• What additional tests are needed to determine the cause more accurately? (e.g., coronary artery testing, electrophysiological testing, genetic testing, etc.)

Reference summary: Ventricular fibrillation is an emergency requiring immediate defibrillation, and identifying the cause and providing rapid treatment determine survival and neurological prognosis. Before an outpatient visit, organizing medication information, test records, and details of the episode can help with diagnosis and treatment planning.