February is the month of love – from candy to toys, stores are filled with everything pink, purple, and red. Meanwhile, school hallways are filled with young lovebirds. Hearts, the ubiquitous symbol of love, are drawn on bathroom walls, hung in chains in the commons, and strewn around entire neighborhoods. For thousands of years, hearts – both the shape and the body part – have been associated with love and emotion. 

The human heart is often regarded as one of the most important organs in the human body, pumping blood around the clock to perfuse the other organs. For most (75-90% of people), the heart does this job quite efficiently. It beats about 100,000 times a day, 35 million times in a year, and three billion times in an average lifetime. The healthy human heart contains four valves, four chambers, one electrical pathway, and many veins and arteries connecting the heart to the rest of the body.

 Deoxygenated blood from veins is pumped from the right atrium into the right ventricle through the tricuspid valve. From there, it travels into the lungs to pick up oxygen from breathing. Blood then flows back into the left atrium and to the left ventricle through the mitral valve and into the rest of the body through arteries. The speed of this process – most commonly known as heart rate or pulse rate – is controlled by the electrical pathway in the heart. This pathway begins in the sinoatrial node (the heart’s natural pacemaker) and ends in fibers that directly cause the ventricles to contract. Because of this pathway, the heart is capable of beating independently of any other system, as long as it is provided with oxygen. However, the autonomic nervous system still moderates heart rate, accelerating it during times of physical or emotional stress and decreasing it during times of relaxation. 

The remaining 10-25% of people, however, have heart defects, meaning at least one component of the heart or nearby systems is malformed or underdeveloped. Heart defects are usually congenital (present from birth) but can also be acquired later in life as a result of illness, injury, or lifestyle. Common heart defects include septal defects (holes in the walls between the left and right sides of the heart), valvular stenosis (causing valves in the heart to fail to open and close properly), and abnormalities involving the arteries and veins in the heart. 

With modern medical technology, over 85% of people with congenital heart defects (CHD) live enjoyable, fulfilling adult lives. Although CHD cannot be cured, symptoms and complications can be treated with surgery, medications, and lifestyle changes. Although most CHD patients are followed by a cardiologist and care team for life, by following a treatment plan, they can do many things their peers do. This includes having romantic relationships, living independently, and, in some cases, even participating in sports. 

Although the heart itself does not cause love, it is inextricably linked with it. Perhaps this is why hearts are so commonly associated with Valentine’s Day. Most teenagers (and former teenagers) are familiar with the jittery, pounding sensation in the chest whenever a romantic interest enters the room, or even whenever a romantic interest enters their mind. This results from the release of the neurotransmitters dopamine and adrenaline, which cause the heart to race (tachycardia). Aside from love, two of the most common benign causes of tachycardia are our favorite mind-killers, fear and anxiety, which are also caused by adrenaline. 

The obsessive thoughts of a lover leading to a jumpy, racing heart are caused by decreased serotonin and increased dopamine from thinking about said lover. Unsurprisingly, most romance comes from the limbic and paralimbic systems in the brain, which are responsible for reactions and complicated emotions. It has little involvement from the prefrontal cortex – people really do lose their heads when falling in love, in a way. 

In the early stages of attraction, when the neurotransmitters dopamine and adrenaline are most prominent, a person’s heart often beats more strongly and quickly, causing a rapid pounding sensation. The nervous system processes budding romance similarly to addictive substances or stimulants, seeking more interaction with a lover, whether in real life or the imagination. Even later in a romance, the heart is involved as partners’ heart rhythms sync when the two embrace.

Not all romances reach this stage, as many young couples break up early in their relationship. Just as anyone who has ever been young and in love knows of the skipping, pounding heartbeat that comes with attraction, most who have ever suffered a break-up have experienced some degree of heartbreak.

 While the actual heart is not usually involved in heartbreak, in rare cases, people can develop takotsubo cardiomyopathy, otherwise known as “broken heart syndrome.” This is caused by swelling of the left ventricle resulting from a surge of adrenaline following a breakup or other stressful life event. The condition causes disruptions in circulation similar to those found in patients suffering heart attacks. Thus, the symptoms often mimic those of heart attacks, so sufferers and their doctors are initially hard-pressed to tell the difference. However, no blockage is present in broken heart syndrome, and the swollen left ventricle can be observed via ultrasound (echocardiogram). Typically, these symptoms are temporary and leave no lasting damage to the heart. In rare cases, however, the condition can cause fatal complications. As such, it is, in fact, possible to die of a broken heart. Perhaps this is actually where the phrase originated. Ancient literature, as far back as the early Roman empire, details bereaved sweethearts dying days after their darlings, buried holding hands. 

Some say the heart falls in love and can see what the brain cannot. Perhaps it would be more accurate to say the limbic system falls in love and sees beyond reasoning from the prefrontal cortex, or simply ignores it. Even though the heart itself cannot “see” anything or feel love, the nervous system – essentially the brain – and heart are closely linked. Therefore, in a sense, whatever the brain feels, the heart feels as well. Although the heart never “feels” love, this Valentine’s Day, you should feel some love for your heart. 

Information retrieved from Harvard Medical School, American Heart Association, Psychology Today, National Institutes of Health