Coronavirus (COVID-19) and the heart

Figure 1: Coronavirus

The first cases of the novel 2019 coronavirus (COVID-19) was reported in Wuhan, China in December 2019 1 and since has rapidly spread worldwide. In its essence, the virus is a non-living strand of protein called RNA enclosed in a fatty acid envelope.

It appears spherical under an electron microscope and has certain particles on its surface which appear like a crown or ‘corona’ (figure 1). Coronavirus can affect the heart in several ways, many of which are still unknown, but the end result is direct injury, heart failure or death.

Why did COVID-19 become such a big deal?

The novel coronavirus has a totally new configuration. Human race has never been exposed to anything like it before, so the entire world population lacks any sort of immunity to this. It seems, every human is susceptible to be infected.

In other words, humans lack antibodies against COVID-19. Antibodies are like special task forces, specialized to disable only one type of foreign cell or protein. These form in the body after an infection or vaccination and prevent future infections with the same organism. Just like the governments around the world are racing to make a vaccine, the human body has its own ‘vaccine lab’ called the plasma cells. Unfortunately, the plasma cells need time while they work on making antibodies. In the meantime, the body sends out its reserve forces against the virus. These soldier cells are not specialized to kill COVID virus and they use any possible means – machine guns, hand grenade, assault tanks against the virus, while the plasma cells can work on making antibodies. In most cases, this is enough to keep the virus suppressed while the antibodies are made. Once the antibodies are ready, the virus is destroyed and the patient recovers after suffering mild symptoms.

In some cases though, the initial response is not enough and the organs (lungs, heart etc.) get caught in this cross-fire between the virus and the soldiers. The result is an overwhelming inflammatory response called a cytokine storm. Cytokines are a byproduct of the war raging inside the infected body. In low levels cytokines help to destroy the virus and only result in mild symptoms like fever. They activate soldier cells all over the body and recruit them to the affected area, like recruiting the military to calm riots inside the country. Cytokines have other favorable functions as well.

However, when the virus levels rise, the war rages on, cytokines build up. Soldier cells all over the body get activated and infiltrate the organs. If the organs are already weak from an underlying disease or old age, they can fail.

Symptoms:

The common symptoms include fever (89% hospitalized patients), cough (68% patients), pain in the throat, headache, tiredness 2. In severe cases it can totally flood the lungs with fluid (pulmonary edema), severely affecting its function. Lungs are like sponge which allow free passage of air, but when soaked in water, no air can pass through. This is called severe acute respiratory distress syndrome or SARS.

For an update on the likely symptoms, refer to the CDC website.

Effect on the heart:

As mentioned above, heart can sustain collateral damage from the cytokines in some cases. There have also been reports of the virus directly injuring heart cells.

Just like the lungs, heart muscle can also get flooded with fluid (myocardial edema) 3 and soldier cells infiltrate the heart. These soldier cells that have been activated by the cytokines are like grenades with pins removed.