The heart is a vital organ as a pump. It pumps oxygen rich blood into the arteries and transports oxygen poor blood into the lungs. The pumping can be easily recognised by the sound: the heartbeat. The heartbeat usually runs like clockwork. However, some people develop arrhythmia which means the heart beats irregular, too slow or too fast. Especially fast arrhythmia can turn into heart arrest.

In addition, the heart often develops a 'one-way disease' which means once established the heart can't reverse the process without outside help. These diseases include heart attack (a blocked heart artery which is often a consequence of coronary artery disease) and valvular diseases (defective heart valves).

Arrhythmia

Arrhythmia is a heart condition with an abnormal heartbeat (irregular, too slow or too fast). Most arrhythmias are harmless and don’t require medical help. A lot of people live a normal life despite having this condition. However, some arrhythmias may become life-threatening. On that occasion, the heart is unable to pump blood into the body properly. This can quickly lead to insufficient blood supply of different body parts such as the heart itself, brain and other organs. Fortunately, most arrhythmias can be treated.



Cause:

  • Heart beat is irregular, too slow (= bradycardia) or too fast (= tachycardia).
  • Development of institial fibrosis in the heart isolates cells from each other.

 

Symptoms:

  • Low blood pressure
  • Palness
  • Shortness of breath
  • Chest pain
  • Dizziness

 

Treatment:

  • Defibrillation (therapeutic dose of electrical shock with a defibrillator to prevent sudden fast arrhythmia)
  • Implantation of a heart-pacemaker (‘listens’ to the heartbeat and produces a small amount of electricity to support the heart in case of a slow/irregular heartbeat)
  • Surgical removal of areas that may cause the arrhythmias (cardiac ablation)
  • Medications

      Heart arrest

      Heart arrest means that the heart doesn't beat any more due to arrhythmia such as sudden ventricular arrhythmia. During that kind of arrhythmia the electrical signals within the ventricles become chaotic and the heart finally stops working.

      Coronary artery disease

      Several factors such as poor diet, lack of exercise and smoking may lead to development of atherosclerosis which is characterised by hardening and narrowing of arteries due to plaque formation (deposits of cholesterol and other lipids). When atherosclerosis occurs in the heart blood arteries (= coronary arteries) it is called coronary artery disease.

      Symptoms of coronary artery disease include angina-discomfort caused by reduced blood flow into the heart.

      Heart attack

      Cause:

      Coronary artery disease that can result in heart attack in 3 different ways:

      • Coronary arteries get clogged up with plaques.
      • One of these plaques ruptures and thereafter causes a blockage of an artery.
      • The plaque rupture stimulates repair mechanisms leading to development of a blood clot at the site of the rupture (like the repair of a popped pimple). This blood clot may block the artery.

      Either way, a blockage prevents the blood from running through the coronary arteries and thus causes death of cardiomyocytes.

       

      Symptoms:

      • Pain in chest, middle back, neck or jaw
      • Vomiting
      • Shortness of breath
      • Indigestion
      • Irregular or rapid heart beat (= palpitations)

       

      Treatment:

      • Coronary angioplasty (non-surgical procedure to widen a partial open coronary artery with an inflating balloon)
      • Coronary artery bypass (a side street around the blocked artery is created by using a vein from the leg or chest placed before and after the blockage)
      • Clot-preventing, blood thinning medications



      Valvular heart disease

      Cause:

      One of the heart valves (mitral, aortic, tricuspid or pulmonary) does not work properly or is defect:

      • The aortic valve controls blood flow between heart and aorta.
      • The pulmonary valve governs the blood flow between the heart and lungs.
      • The mitral and tricuspid valves enable blood flow between atria and ventricles.

       

      Symptoms:

      To compensate for the poor pumping action the heart gets bigger (= pathological cardiac hypertrophy).

       

      Treatment:

      • Valve surgery to repair or replace a damaged valve
      • Balloon dilation to widen a stenotic valve
      • Clot-preventing medications

       

      An heart valve defect can be further characterised by two different subsets:

      Valvular stenosis:

      The valve becomes hard and narrowed (stenotic). Thus the reduced opening of valve leads to restricted blood flow into the next compartment.

      Valvular insufficiency:

      The valve does not close tightly and therefore blood ‘leaks’ back into the previous compartment.



      Literature

      Heart attack/coronary artery disease:

      http://www.bhf.org.uk/heart-health/conditions/heart-attack.aspx

      http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001246/

      Cardiac valve disease:

      http://www.ncbi.nlm.nih.gov/books/NBK2220/

      Arrhythmia:

      http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0002091/

      http://www.ncbi.nlm.nih.gov/books/NBK2219/

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