PRE-UNIT STUDY TIPS

• 心脏疾病的重点是解剖结构和心脏的工作原理，明白心脏是怎么正常工作的就可以推出来不同的疾病是怎样的情况
• 心脏疾病通常会伴随放射痛，假设病人提出腹痛的主诉，那么在考虑消化系统疾病的同时也需要排除心脏疾病的可能
• 注意区分心绞痛和心肌梗死，重点看对药物反应的不同
• 注意区分肺心病和肺水肿，重点看两种病因果关系的不同
• 关于心脏的信号传导，建议大家配合crash course视频食用，更直观一些易懂
• 几种先天性心脏病都比较复杂，建议对着得病的解剖示意图想一想血液是怎样流的，会出现怎样的症状，这样比直接背症状要更好

1. Coronary Artery Disease (CAD) 冠心病

• narrowed by atherosclerotic deposits, causing temporary cardiac ischemia and eventually MI (or heart attack)

• signs & symptoms:

  • asymptomatic initially
  • first: pain of angina pectoris
  • advance:
    • burning, squeezing, crushing; radiating to the arm, neck, jaw
      • due to diminished blood flow and lower O2 saturation
    • Nausea, vomiting, and weakness

• etiology:

  • atherosclerosis: deposit of plaque (fat-containing substances) in the lumen
    • the arteries lose elasticity, resulting in cardiac ischemia
    • replacement scar tissue forms, resulting in heart failure

• risk factors:

  • 40+, men, postmenopausal women, Caucacians
  • smoking, residence in urban societies, presence of hypertension, diabetes, obesity
  • history of elevated serum cholesterol or reduced serum high-density lipoprotein (HDL) levels
  • lack of exercise, stress

• diagnosis:

  • ECG: ischemia, arrhythmias
  • treadmill testing, thallium or Cardiolite scan, CT, stress echo-cardiograms, cardiac catheterization, and angiograms: insufficient O2 supply, confirm
  • electron beam computerized testing (noninvasive): Ca buildup in arteries

• treatment:

  • vasodilators
  • angioplasty with a balloon or stenting
  • hypolipemic drug
  • first line drugs: angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers (ARBs), calcium channel blockers (CCBs), thiazide diuretics or vasodilators
    • beta-blockers and anticoagulants: prevent blood clots from breaking off & lodging in cerebral arteries
  • if severe & no respond: coronary artery bypass surgery
  • gene therapy: injection of DNA into cardiac muscle to stimulate new growth of blood vessels

  1.1 Angina Pectoris 心绞痛

  • chest pain due to ischemia: reduced O2 supply to myocardium

  • signs & symptoms:

    • onset of left-sided chest pain during or shortly after exertion
    • pain may radiate to the left arm or back

    

    • dyspnea
    • pain usually is relieved by ceasing the strenuous activity and placing nitroglycerin tablets sublingually or using nitroglycerin spray sublingually

  • etiology:

    • atherosclerosis
    • spasms of the coronary arteries
    • severe prolonged tachycardia, anemias, and respiratory disease

  • diagnosis:

    • ECG taken during the angina episode may show ischemia; a normal ECG does not preclude the diagnosis of angina
    • those described for CAD are performed

  • treatment:

    • cessation of the strenuous activity
    • placing nitroglycerin tablets sublingually
    • transdermal 经皮的 nitroglycerin

  1.2 Myocardial infarction (MI) 心肌梗死

  • death of myocardial tissue caused by ischemia

  • signs & symptoms:

    • sudden severe substernal 胸骨下的 or left-sided chest pain
    • the pain may be crushing, causing a feeling of massive constriction of the chest, may be burning, or may just be a vague discomfort
    • the pain may be radiating to the left or right arm, back, jaw

    

    • the pain is not relieved by rest or the administration of nitroglycerin

    • irregular heartbeat, dyspnea; diaphoresis 发汗, nausea

    • patients usually exhibits denial & experiences severe anxiety, sometimes with the feeling of impending doom

    • MI occasionally is clinically silent, especially in diabetics.

      *糖尿病为什么会造成心脏病？为什么临床症状不明显？

      尤其是二型糖尿病，与心血管疾病有很大关联。高血糖会损坏血管壁，降低血管的弹性，也可能会造成炎症。糖尿病患者一般伴随着脂质代谢异常，脂质在血管内壁堆积容易造成动脉粥样硬化。

      糖尿病患者经常伴随神经病变，高血糖本身也会干扰疼痛传导系统，导致痛觉减弱或消失。糖尿病会导致微血管病变，当心肌梗死发生在微血管时，症状不明显。

  • etiology: insufficient O2 supply caused by atherosclerotic plaque, thrombus, or myocardial muscle spasm

    • if ischemia is not reserved within about 6 hours, the cardiac muscle dies.
    • Coronary thrombosis is the most common cause of MI.

  • diagnosis: history, chest radiograph

    • ECG
      • changes in the P-R and QRS complexes and in the ST segment
    • lab test for cardiac enzyme levels (confirm)
      • creatine phosphokinase (CPK) and troponin: elevated in the 1st 6~24hr after MI
      • lactate dehydrogenase (LDH): peaks at 48 hours after MI
      • aspartate aminotransferase (AST): elevated
    • blood tests
      • altered isoenzyme levels (confirm)

  • treatment:

    • O2, morphine for pain
    • aspirin given ASAP: reduce the risk for additional damage to the heart and tissue by ischemia
    • nitroglycerin drip: vasodilation
    • Lidocaine or amiodarone are given by IV drip after a loading bolus (快速大量注射): helps to ctrl arrhythmias
    • thrombolytic drugs such as tissue plasminogen activator (TPA), streptokinase, or alteplase (Activase) administered ASAP after dia
    • within the 6hr window: open the occulusion by angioplasty, thrombolytic drugs, or coronary artery bypass

  • prevention:

1. Cardiac Arrest 心脏停搏

• sudden, unexpected cessation of cardiac activity
• signs & symptoms:
• etiology: