Diseases of the body: The Heart
The structural disturbances depend on many causes – genes, diseases in the prenatal period or postnatal period, infections and inflammations.
The structural disturbance can be in the valves, in the muscle walls of the heart, or in the electrical current routes. Other structural malformations can also happen in the great vessels of the heart – such as the pulmonary vein and the aorta. Severe structural diseases can decrease life quality, and in worst case - kill the patient.
The septa in the heart, separates the heart chambers so the heart can have a systematic way of oxygenating blood and then delivering it to the body. Septal defects between the different chambers can make the blood run the opposite way, disturbing the systematic flow allowing it to be oxygenated and then pumped out to the body. The body would not receive enough oxygenated blood and the person might appear somewhat blue (cyanotic) according to the degree of oxygenated blood.
As explained earlier about the normal heart function, there is an electrical current which helps the heart (muscles) function as one whole unit. If there are disturbances in these electrical currents, there will be problems with the hearts function which further leads to consequences for the whole body.
If the heart does not work as one unit, this would cause disturbances in the heart rhythm, which your physician can detect through either listening to your heart with a stethoscope or by interpreting your ECG.
Since the heart is made of 4 chambers – 2 atria and 2 ventricles, disturbances in the rhythm can either be in the atria, ventricles or both. The degree of severity would be determined by type, localisation and the degree of disturbance.
“Arrhythmia” is the medical term for disturbance of the heart rhythm. Arrhythmias could cause changes in the speed or regularity of the heart rhythm – and in worst cases, they can cause sudden death.
Electrical current stimulating the heart to contract so it can pump blood through the body, starts always at point in the atria called the Sino-Atrial-Node. From here on, the current moves down to the ventricles and the whole heart can start contracting in a consecutive manner. However, in arrhythmias can happen, and most often they are caused by several places in the heart trying to become the Sino-Atrial-Node. This causes an irregular rhythm because the heart does not get stimulated in a consecutive manner, but in a disorganised manner.
The heart and the circulation are tightly bound to each other because they cooperate to keep the body fuelled with nutrition and oxygen. Sometimes, when the circulatory system starts to fail at keeping normal blood flow to the heart, the heart suffers and in the end – the body would suffer too. The heart is not the only organ needing blood flow, and other organs are also in risk of malfunction when there is decreased blood flow to them.
Infarcts (death of tissue) of the heart are mainly due to reduced or no blood supply to the heart at all. Because the coronary arteries are the main blood supply to the heart, any problems such as obstruction or any diseases that causes destruction of them, will make the heart hungry for blood and oxygen. In the end, the heart cannot keep up the working load and would seize to work.
Stroke is an infarct in the brain. The heart is responsible for pumping blood to the brain. Any abnormalities in the function of the heart such as in arrhythmia and myocardial infarction, or obstruction of the vessels to the brain, will cause the brain to have infarcts.
Obstruction or narrowing of the vessels causes often problems for organs. Obstruction can happen due to blod clots, increased depositions or calcification in the wall of the vessel. Blood clots can form in both the veins and the arteries, although more common in veins. Blood clots can also form in the heart. Blood clots can either be due to components (proteins) in the blood, red blood cells or platelets. The result is obstruction of the vessel, which can lead to decreased blood flow (ischemia) of the certain tissue in that specific localisation. Such obstructions are called thrombi and if it can move through the body, we call it emboli. Also fat or air bubbles can cause emboli. Emboli causes worry because they can move and obstruct any vessel on the way. When they are stuck somewhere in the circulation, that is when problems start. Emboli get especially stuck in the lungs.
Narrowing of the vessels can happen due to age, deposition of fat or other calcifications. Also in this case blood flow decreases to the organ(s) involves, and cause ischemia. Narrowing of blood vessels also cause hypertension, because the heart must pump blood with a higher pressure for the blood to get past the narrow segments of the vessels. The same thing happens when the vessels are totally obstructed, such as by thrombi. Hypertension causes damage to organs in the long run because of the high pressure and flow. Since the heart has a higher work load now, it can result in heart failure later. Another organ sensitive for the high pressure are the kidneys.
Here you can see how coronary arteries, the vessels supplying the heart with nutrients and oxygen, can get obstructed and cause infarcts in the localisation in which the obstruction happens. If the infarct is small, the person might survive due to the rest of the heart muscle compensating. However, if the infarct is huge, it can cause death.
This is a basic scheme of how a blood clot/thrombus can look like, and how it can obstruct a whole vessel. The thrombus exists of red blood cells which are tightly bound by fibers keeping the clot together.
This scheme of an embolus, shows how the embolus can travel through vessels and finally reaching a vessel it cannot travel through, and thus also cause an obstruction just as the thrombus did.
Author: Bano Imam Afange (KEMSA Vice President)