The Heart, Brain, and Lungs—An Inseparable Partnership

• Heart disease, stroke, and respiratory or lung diseases are well-known to be related to each other. Diseases may occur simultaneously in more than one of these body systems, or the occurrence of a disease in one of the systems may be the cause of a disease in another. 
• The American Heart Association (AHA) stated in 2018 that out of every 100 patients with heart disease, as many as 17 were at risk of stroke. 
• Practicing good self-care by managing controllable risk factors, and being proactive by undergoing screening with medical professionals & Updating Tools who can help identify these diseases in their earliest stages, can help reduce the risk of disease progression, severity, and any complications that could affect other related systems.  

Heart disease, stroke, and respiratory or lung diseases are well-known to be related. According to a 2019 report by the World Health Organization (WHO), the top 3 leading causes of death worldwide were found to be ischemic heart disease, stroke, and chronic obstructive pulmonary disease, in that order. These conditions are related to each other in the following ways: 

Because the risk factors for both systems are very similar, these two diseases may occur nearly simultaneously. These risk factors include hypertension, diabetes, hypercholesterolemia, smoking, obesity, physical inactivity, and regular consumption of alcoholic beverages. All of these risk factors accelerate or facilitate the formation of plaque (fatty deposits) that stick to the insides of the coronary arteries, the carotid arteries, and the arteries of the brain. When this plaque builds up, it can cause acute coronary and/or cerebrovascular disease, or acute coronary syndrome and/or acute stroke. Additionally, if a piece of plaque breaks away from the wall of the carotid artery and moves to the smaller arteries of the brain, this too can cause a stroke. The above risk factors can also result in fragile, unhealthy arteries, leading to cerebral or abdominal aortic aneurysms, which can eventually rupture and cause bleeding in the brain or abdomen, resulting in a high risk of death. 

At the same time, acute coronary syndrome/cardiac arrhythmia can cause some blood to remain in the ATRIUM (Upper chambers of the heart) , and this residual blood can cause blood clots in the chambers of the heart. If a blood clot breaks loose and travels through the bloodstream, it can move to the brain and clog blood vessels there.  Arrhythmias carry with them the highest risk of stroke, and this risk may be 5 times as high for patients with additional diseases. Studies have also shown that coronary artery disease, or ischemic heart disease, is second only to cancer as the most common cause of death among Thai people.  A report from the American Heart Association (AHA) states that in 2018, out of 100 patients with heart disease, as many as 17 of these were at risk of stroke. As such, it is imperative that these conditions are controlled appropriately and that they are monitored and treated early on.  

Smoking is the leading cause of lung disease, the most common of which include lung cancer and chronic obstructive pulmonary disease (COPD), such as emphysema. These contribute to a higher workload on the heart due to higher than usual resistance in the lungs and thus higher pressure in the blood vessels carrying blood back to the heart, resulting in an increased risk of arrhythmias. In addition, emphysema can increase blood pressure in the pulmonary arteries (pulmonary hypertension), which can result in right-sided heart failure, a dangerous condition that causes severe fatigue and weakness and eventually death. Studies also show that out of every 100 patients with COPD, 25-33 of these will die due to heart disease—a very high number, to be sure. Additionally, for those with pulmonary embolisms, if the condition becomes acute it can cause cardiac arrest or acute right-sided heart failure, or, in chronic cases, pulmonary hypertension. 

Conversely, there are a number of heart diseases that affect the lungs as well, such as ischemic heart disease. Narrowing of the coronary arteries or the narrowing or leakage of aortic valves impair blood flow from the heart. In these cases when the heart is not functioning as it should the result may be blood clots in the heart and blood backing up into the veins that take blood through the lungs. When pressure increases, excess fluid is pushed into the alveoli in the lungs, causing a pulmonary edema. This can cause problems with the exchange of oxygen and carbon dioxide, resulting in breathing difficulty and poor oxygenation of blood. Symptoms include shortness of breath, extreme fatigue and trouble breathing when lying down and/or waking up to breathe after falling asleep. If not treated properly or in a timely manner, this condition can be life-threatening.  Moreover, when these lung and heart diseases occur simultaneously, it results in increased mortality rates.  

Both of these diseases carry a risk of comorbidity. Smokers in particular have a higher likelihood of developing both types of diseases at the same time. Lung diseases, such as pulmonary embolism together with atrial septal defect, are among the leading causes of stroke. In some cases, a blood clot may travel through the bloodstream from the lungs to the brain, causing a stroke. Blood clots may also be caused by blood thickening, resulting in blood clots forming in the blood vessels throughout many parts of the body, most commonly in the vessels of the lungs, legs, and brain. In addition, many types of cancer, including lung cancer, are also risk factors for blood clotting.   

On the other hand, stroke patients with disabilities and an inability to move around also have increased risk of blood clotting in the vessels of the legs. A blood clot breaking free and moving from the leg to the lungs can result in a pulmonary embolism. 

If you have high blood pressure, hyperlipidemia, or diabetes or if you are overweight, smoke or consume alcohol on a regular basis, are constantly stressed, are over 50 years old and have a family history of any of the at-risk diseases, especially in a direct relative, then you may be at risk of heart disease, stroke, or lung disease. Occasionally, these diseases may be found in younger patients, especially in those with a combination of risk factors. This is the case even in patients who exercise vigorously and regularly. 

As outlined above, the connection between these 3 systems or organs is clear. If there is risk present for any one of these diseases, it may increase the risk of developing diseases in the other two systems as well. It is important, therefore, to undergo screening for these diseases early on, even before experiencing symptoms. Screening can be carried out as follows: 

• Coronary Calcium Score CT Scan evaluates plaque buildup in the coronary arteries using computed tomography to screen for cardiovascular system disease 
• Carotid Duplex Ultrasound examines the carotid arteries to screen for diseases of the brain and nervous system  
• Low-dose CT Chest Screening is a low-dose computed tomography of the lungs to screen for respiratory diseases 

It is also advisable to practice good self-care by managing controllable risk factors such as blood pressure, blood sugar and lipids, smoking, weight, etc. In addition, being proactive in undergoing screening with medical professionals can ensure these diseases are identified in their earliest stages, which can help to reduce the risk of disease progression, severity, and any complications that could affect other related systems.