The heart is one of the vital organs necessary for survival. If the heart stops working, life stops too. The thyroid, another organ located at the base of neck, influences the heart to a great extent. Although every organ and system in our body is related to one another to make life possible, the thyroid and heart have a really close association.
The circulatory system consists of the heart, considered as pump, which is connected to blood vessels which act as tubes or channels. To understand how the thyroid affects heart, you first need to know how the heart functions. The heart has two sets of blood vessels. One set of vessels supply the heart with blood as every other organ is supplied with blood. These vessels are known as coronary arteries. The other set of vessels are the arteries and veins connected to heart, that supply and receive blood from all other organs. These vessels make a loop with heart. Concluding, heart supplies blood to all organs in the body and also supplies its own self.
Effects Of Hyperthyroidism On Heart:
Hyperthyroidism is the overactivity of thyroid gland that causes excess thyroid hormones in blood. Large amounts of thyroid hormones increases the metabolism even more than normal. The common symptoms associated with hyperthyroidism are increased heartbeat, palpitations, anxiety, mood swings, diarrhea, tremors and unexplained weight loss. How hyperthyroidism particularly affects thyroid is explained below.
- Increased heartbeat:
Tachycardia is the term used for increased heartbeat. Tachycardia is a normal response of body in fight and flight conditions. However, an increased heart beat that doesn’t come back to normal, even when the stimulus is gone, is an abnormal marking. The question is why our heart needs to beat faster in hyperthyroidism? The answer is because of increased metabolism. As metabolism accelerates, so does the need of blood by the organs responsible for metabolism. It’s because blood provides increased oxygen and other nutrients to these organs to meet the increased need of work. Unfortunately, it is done at the expense of heart. The heart needs to beat faster to assure enough blood reaches every organ, in turn increasing its workload. Increased demand on the heart causes it to fatigue and also damages its muscles.
Palpitations are an increased heartbeat that can be sensed by the person as strong or irregular heartbeat. It is perceived as if the heart is jumping, flopping, fluttering or racing. You may feel palpitations occasionally when your sympathetic system is activated, that is considered normal. Palpitations are not worrisome until they occur at rest or for prolonged period of time. But unfortunately, that is the case in hyperthyroidism. In simple words, palpitations are an advanced form of tachycardia, that cause increased workload on heart and consequently damage it.
- Atrial Fibrillation:
Atrial fibrillation is an irregular heartbeat. The most common heart condition in hyperthyroidism is atrial fibrillation (The American Journal of Medicine, Jan, 2015). Basically when workload of the heart increases, it starts beating really fast to accomplish the task that it is assigned. In making an attempt to fulfill body’s needs, the increased heartbeat can become irregular.
When the heart quivers instead of pumping steadily, it causes clot formation. Therefore, an irregular rapid heartbeat increases the chance of stroke and heart failure. If left untreated, it can pose life threats too. Therefore, it is really important that atrial fibrillation should be timely diagnosed and treated by your medical doctor.
Decreased Oxygen Supply To Heart:
Increased workload on the heart, associated with hyperthyroidism, adversely affects it by decreasing its own blood supply. As mentioned earlier, the heart is supplied by its own arteries like all other organs. Decreased blood supply cuts off oxygen supply causing the heart cells to die through lack of blood supply, aka ischemia.
- Increased Blood Pressure:
Blood pressure usually remains normal because of increased blood supply to organs by vasodilation (dilation of vessels). However the systolic blood pressure rises because of prolonged contraction of the heart. High systolic blood pressure can easily be felt as a throbbing pulse at the wrist.
Effects Of Hypothyroidism On The Heart:
Hypothyroidism is the underactivity of the thyroid gland that decreases thyroid hormones levels in the blood. The classical symptoms associated with hypothyroidism are fatigue, weight gain, slow heartbeat, constipation and cold intolerance. Hypothyroidism specifically affects heart by;
- Decreased Heartbeat:
Bradycardia is the slowness of heart beat. It does not produce any symptoms. However, bradycardia causes decreased blood supply to the different organs of body, including the heart that is also supplied by its own arteries. As a result of compromised blood supply, different organs can failure, including the heart itself.
- Decreased Blood Pressure:
In hypothyroidism, blood pressure decreases initially. The other relevant event that occurs is the accumulation of cholesterol due to low metabolism as a result of decreased thyroid hormones synthesis. Accumulation of cholesterol in arteries narrows them down impeding the blood flow. Superimposed low blood pressure further compromises the circulation of blood.
As blood supply to the organs decreases, including the coronary arteries of heart, angina and even heart attacks can occur. The prolonged hypothyroidism ultimately increases the blood pressure due to increased blood demand of the organs (caused by decreased blood supply), putting an additional demand on heart. This further increases the chances of stroke and heart failure.
- Heart Failure:
Heart failure occurs when the heart does not pump blood efficiently to meet the needs of organs, including the heart itself. To compensate its inability to pump enough blood, the heart still tries to work hard. This leads to increased volume of the heart chambers. Although it is advantageous initially for a short period of time, later it compromises oxygen supply to the heart by creating a vicious cycle of potential heart failure. Heart failure can be an outcome in both hypothyroidism and hyperthyroidism. It can be one of the worst complications of thyroid problems (Schmidt-Ott and Ascheim DD, Curr Heart Fail Rep, Sep, 2006).
Thyroid problems, whether it be hyperthyroidism or hypothyroidism, adversely affects the heart. Overproduction of thyroid hormones increases the workload of the heart which can damage heart muscles. Furthermore, it causes compromise of blood supply to the heart muscles, as the blood is directed more towards the metabolizing organs. Increased workload and decreased blood supply results in ischemia or infarction of heart muscles. On the other end, underproduction of thyroid hormones decreases the heart function. This results in compromised blood supply to all the organs including the heart. Ultimately, heart failure can ensue.