Author: Aekta Shah, M.D., MRes (Translational Cancer Medicine) Associate Professor and Pathologist. Member: Neuro-oncology Disease Management Group, Tata Memorial Hospital, Homi Bhabha…
Authors: Courtney Doherty is an undergraduate student studying Biomedical and Mechanical Engineering at Colorado State University. Michael Nguyen-Truong is pursuing a PhD in Biomedical Engineering at Colorado State University.
We’ve all heard it before: cardiovascular diseases are the leading cause of death worldwide. These diseases include heart disease, heart attack, stroke, heart failure, arrhythmia, and heart valve problems, according to the American Heart Association.
Most of these cardiovascular diseases are commonly heard of, but one of them has been labeled a global pandemic affecting at least 26 million people worldwide—and it is unlike the one that is currently dominating our air and lungs, headlines, and headspaces. It is known as heart failure, a clinical syndrome damaging the left or right (and sometimes both) sides of the heart. Despite their importance, these individual but connected entities have not received equal attention.
In the historical context of research on heart failure and function, the right heart (referred to as the “right ventricle” in this article) has received less attention than the left heart (referred to as the “left ventricle” in this article) in cardiac research. It has even been deemed an unnecessary and a passive chamber eclipsed by its left counterpart even with it having caused irregularities in about 70 million people across the United States.
The right ventricle is clearly distinct from the left ventricle in its anatomy, geometry, and physiology, even though the two components work together in unison. The left ventricle has a rounded bullet shape and is a physically thicker muscle than the right ventricle. In contrast, the right ventricle can be seen as more of a crescent shape (which actually makes it harder to image using traditional methods such as 2-D echocardiography, a non-invasive ultrasound imaging technique). Given these differing characteristics, the knowledge of the left ventricle cannot simply be applied to the right ventricle: research must be done specifically on the right ventricle to gain a better understanding of it.
During this more urgent global COVID-19 pandemic, the coronavirus has been reported to cause cardiac complications such as myocarditis. Beyond this potential inflammatory response that attacks the heart when myocarditis occurs, there has also been research showing strong correlations between right ventricle abnormality and hospitalization outcomes.
In a small study in the Journal of American College of Cardiology: Cardiovascular Imaging from Mount Sinai Heart, the right ventricle was shown to be dilated and had a strong association with in-hospital mortality of COVID-19 patients. A later, larger study in the Journal of the American College of Cardiology from Weill Cornell Medicine found that adverse right ventricle remodeling was a prognostic parameter that could be a predictor of COVID-19 mortality. From their cohort of hospitalized patients, right ventricle dilation was reported as 35% prevalent and dysfunction was 15% and both abnormalities were associated with increased mortality risk. The results from these two studies suggest that right ventricle remodeling may have a correlation to COVID-19 hospitalization and death and could possibly be used to predict these occurrences.
Even before the pandemic, right ventricle dysfunction and failure in cardiac diseases such as pulmonary hypertension or left heart diseases were shown to be useful predictors of morbidity and mortality. For instance, right ventricle failure due to pulmonary hypertension has been reported to have a mortality rate of 33-38% three years post-diagnosis. Data regarding the prevalence and mechanisms of right ventricle dysfunction remain limited and incomplete though. In 2006, the Working Group on Cellular and Molecular Mechanisms of Right Heart Failure of the National Heart, Lung, and Blood Institute stated that there was a “…paucity of basic knowledge at all levels about [the right ventricle’s] normal and pathological functions…” Given the publication of the report 15 years ago and despite its clinical relevance, the right ventricle still lacks effective management and treatment.
The right heart was recently cast into the spotlight due to COVID-19; it is a much-needed prioritization on an underappreciated part of this vital organ. The left heart’s partner in crime is thankfully now receiving more recognition and research given its importance to our cardiovascular health, but there is still much more to be done. It is about time we give more love to the right heart.