Understanding the Heart

By Dr. Jeffrey Brock

The heart is a powerful ‘machine’ which integrates pumping, electrical, fuel delivery and valve systems. Heart disease is very common but many individuals fail to know and seek medical help for the common early warning signs. To better understand heart disease, one must understand each system. 

The Pump

Deoxygenated blood from the body enters the right side of the heart and is pumped to the lungs for oxygenation then to the left side of the heart for circulation to the brain and rest of the body.

Congestive Heart Failure is a reduction in cardiac output with symptoms of swollen feet/ankles, shortness of breath while walking or lying down and fatigue. This is treated with medications.

The Electrical System

While heart cells are fueled by oxygen, an electrical system ‘fires’ synchronous heart cell contractions for smooth coordinated pumping. Electrical impulses from the atria then pass to the ventricles. Malfunctions can lead to two serious conditions;

  • Atrial Fibrillation – Failure of the two atria to contract synchronously increases the risk of stroke due to blood clots traveling from the heart. Treatment is with blood thinners.
  • Sick Sinus Syndrome or Heart Block – Failure of the electrical system to generate and conduct impulses disrupts normal heart function. Treatment is with medications or a pacemaker which generates the electrical impulses.

Symptoms of these can include palpitations, generalized weakness, fainting, dizziness and fatigue.

The Fuel Delivery System

Blood from the coronary arteries provides oxygen to all heart cells. Cholesterol plaques can build up and block these arteries causing Coronary Artery disease and;

  • Angina – Chest pain/pressure either at rest or on exertion.
  • Heart Attack or Myocardial Infarction – A complete blockage leading to the death of heart cells, abnormal electrical activity and reduced pumping of blood.
  • Sudden Death or Cardiac Arrest – Blocked arteries can cause failure of the electrical system and sudden death. Unfortunately this is the most common presenting symptom of Coronary Artery disease.

Symptoms of Coronary Artery disease can include chest pain or pressure at rest or on exertion, ‘a feeling of indigestion’, shortness of breath or fatigue. These are very serious and should be assessed promptly by a Physician in an Emergency Room. Treatment is with medications, angioplasty or heart by-pass surgery.

The Valves

Four valves control the flow of blood between the atria, the ventricles and the main arteries leaving the right and left heart.

Blocked or leaky valves cause pump overload and insufficient blood circulation to the body. Symptoms include shortness of breath, swollen feet/ankles and fatigue. Surgery is used to replace or open up these malfunctioning valves.

Healthy Heart Tips


• Brisk walk or aerobic exercise for 30 minutes 4 times weekly

• Maintain a ‘slim’ body weight

• Have regular check-ups for blood pressure and cholesterol

• Avoid fatty or fried foods

• Avoid sugar and sugary foods


• Use tobacco

• Drink alcohol excessively

• Gain excess weight


Dr. Jeffrey Brock practiced Emergency Medicine for 15 and is now President and CEO of Montreal, a Montreal, Canada based provider of corporate health services.

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