Page 32 - Layout 1

COVID-19 UPDATE

A Disease of Insufficient Nitric Oxide Production

By Nathan S. Bryan, PhD

3
COVID-19 is now a worldwide pandemic affecting millions of untreated cardiovascular conditions. It is clear that older people with
people around the world. As of mid-May 2021, over 160 million peo- an underlying comorbidity such as high blood pressure, heart disease,
ple have been infected, with over three million deaths. Early data com- kidney disease, obesity, smokers and patients with pulmonary disor-
ing out of China in January 2020 revealed that patients with ders are at an increased risk of COVID infection. These are also the
underlying cardiovascular disease were more susceptible to infection, people that get the sickest and die from COVID.
greater disease severity and ten times higher mortality. Among the pa- Additionally, abnormal blood clotting is an increasingly recognized
tients studied, the median (range) age was 64 (21-95) years old, female complication of this disease, both systemically and within the pul-
4
(50.7%, and the median time to symptom onset was 10 days (in- monary circulation. In fact, one of the greatest predictors of death is a
terquartile range [IQR]), 1-30). Of this group, 82 (19.7%) had some serum blood test that indicates elevated clotting activity (D-dimer).
type of cardiac comorbidity. It was apparent as the study went on that More recent clinical observations reveal endothelial cell infection and
patients with cardiac morbidity and COVID-19 fared worse than the endotheliitis in COVID patients across vascular beds in multiple
5
patients with COVID-19, but no history of cardiac morbidity. Pa- organs. The vascular endothelium is an active paracrine, endocrine and
tients with cardiac morbidity with diagnosed COVID-19, compared autocrine organ that is indispensable for the regulation of vascular tone
with patients without cardiac morbidity, had a higher mortality rate and the maintenance of vascular homoeostasis. COVID-19-endothe-
6
1
(51.2% vs 4.5%) and risk of death. liitis could explain the systemic impaired microcirculatory function in
In addition, over the past 18 months, reports from the U.S. database different vascular beds and their clinical sequelae in patients with
compiled by CDC report mortality from COVID-19 to have a racial COVID-19. Endothelial dysfunction and insufficient nitric oxide
2
disparity. A disproportionate number of COVID-19 fatalities among (NO) production is a principal determinant of microvascular dysfunc-
Hispanics and African Americans has been observed. This has been tion by shifting the vascular equilibrium towards more vasoconstriction
attributed to known disparities in health care, low economic resources with subsequent organ ischemia, inflammation with associated tissue
and issues associated with social distancing: occupation, crowded res- edema and a pro-coagulant state. See illustration. Therefore, the people
idential spaces and transportation crowding. Additionally, Hispanics that are most susceptible and vulnerable to COVID infection are exactly
and African Americans have a high incidence of pre-existing and often the patients that have insufficient nitric oxide production in their body.

32 SAN ANTONIO MEDICINE • July 2021