COVID-19 Affects More than Just the Lungs

Thanks to the work of researchers and physicians, we now know that SARS-CoV-2 can attack more than just the respiratory system. Like the previous two coronaviruses that caused pandemics, SARS-CoV-2 can directly and indirectly cause cardiovascular and renal complications. That’s the focus of the open access review titled “Cardio-Pulmonary-Renal Consequences of Severe COVID-19”. This post looks at some of the authors’ findings.

How Does the SARS-CoV-2 Virus Affect Other Organs?

First, it’s important to understand how SARS-CoV-2 enters cells and causes damage. The virus uses its spike protein to bind to an enzyme (ACE-2) found on the surfaces of certain cells. Another enzyme (a protease called TMPRSS2) cleaves the spike protein, making the virus release peptides that allow the virus to fuse to the membrane and enter the cells. Cells with a high amount of ACE-2 and TMPRSS are thus more susceptible to SARS-CoV-2 infection.

The heart, lungs, kidneys, and intestines all express high amounts of these two enzymes, so these organs are all at risk. That’s among the reasons why there is a range of symptoms for COVID-19: Not every patient has SARS-CoV-2 infecting the same organs to the same degree. For example, if the virus was more abundant in the kidneys and lungs of one patient, they might have acute kidney injury along with difficulty breathing. If another patient had a high intestinal presence of COVID-19, diarrhea might result.

What Effects Does SARS-CoV-2 Have on the Lungs, Heart and Kidneys?

When SARS-CoV-2 infects cells in the lungs, it can directly injure them. For example, it can damage the alveoli (the “bunches of grapes” where carbon dioxide and oxygen exchange occurs); cause congestion of the capillaries that line the alveoli; kill off the lining of air spaces in the lungs; and lead to fluid filling air spaces in the lungs. Even in asymptomatic COVID-19-positive people, scarring and inflammation in the lungs is found. Indirect injury can come from a range of sources, including mechanical ventilation, problems arising from inflammation and dysfunction in the vascular system, and hypertension.

Cardiac injury is common in critically ill COVID-19 patients. This can be direct damage from SARS-CoV-2 infection of cardiac cells and the blood vessels surrounding the heart. It can also be indirect, for example due to drugs being used to treat other symptoms; inflammation and dysfunction in the vascular system; or from sepsis.

COVID-19 can also injure the kidneys directly or indirectly. SARS-CoV-2 has been shown to invade renal cells, causing symptoms ranging from increased levels of protein in the urine (proteinuria) to acute kidney injury. Around 20% of patients with severe COVID-19 even require long-term dialysis or a kidney transplant. Indirect kidney injury can come from a range of sources too, including septic shock, drug-induced nephropathy, and, again, inflammation and dysfunction in the vascular system.

This repeated mention of the impact of problems in the vascular system illustrates a topic that the authors emphasize in the paper: The heart, lungs and kidneys have a strong interaction to the point where injury to one can influence the others. In particular, they discuss cardiorenal syndrome: when an acute or chronic dysfunction in the heart negatively affects the kidneys and vice versa. Cardiorenal syndrome may play an important role in severe COVID-19.

What Is Long COVID?

Although the paper “Cardio-Pulmonary-Renal Consequences of Severe COVID-19” does not deal with long COVID (or post-COVID-19 syndrome), it is certainly relevant to mention. The British National Health Service (NHS) and the World Health Organization (WHO) defines long COVID as disabling symptoms that last weeks or months after the infection has gone. The WHO also states that it may include disabilities that are likely to be very long lasting. Both organizations point out that the symptoms during infection do not need to be severe for long COVID to occur.

Symptoms include fatigue, insomnia, difficulty concentrating, breathing problems, heart palpitations, pain, digestive issues, changes to the sense of smell or taste, and even skin conditions. Long COVID is something that still requires research.

What Can I Do to Protect Myself?

Following public health guidelines is still important: The pandemic is not over. At the time of writing, just 15.5% of the global population is fully vaccinated. In so-called high-, upper middle-, lower middle- and low-income countries, respectively roughly 56, 39, 19 and 1.1% of the populations have been vaccinated. Epidemiological research indicates that it’s still likely that variants will arise and spread. Masking, social distancing, hand sanitizing and continuing global vaccination programs are all essential.

Beyond that, having a full awareness of your cardiovascular and kidney health is critical. If you’re concerned, talk to your doctors about ways that you can improve the health of your heart, circulation, and kidneys.

Finally, be aware of the conditions and behaviors associated with higher risk of severe COVID-19, which include cardiovascular disease, chronic kidney disease, hypertension, diabetes, obesity, asthma, and smoking. If you test positive for COVID-19 and have concerning conditions or behaviors, talk to your doctors about proactive hemodynamic management of COVID-19, as detailed in the fourth and fifth sections of “Cardio-Pulmonary-Renal Consequences of Severe COVID-19”. Proactively monitoring the heart and other important parameters in the emergency department and outside of intensive care could ensure that problems are detected early, possibly preventing hospitalizations and the development of complications in the heart, lungs, and kidneys.

Want to know more about kidney health and COVID-19? I’ve written another post focusing on acute kidney injury and how it can worsen the impact of other conditions, including COVID-19.