Impact of Right Ventricular‐Pulmonary Circulation Coupling on Mortality in SARS‐CoV‐2 Infection

Echocardiography assessment of right ventricular-pulmonary artery coupling: Validation of surrogates and clinical utilities

Right ventricular-pulmonary artery (RV-PA) coupling indicates efficiency of energy transfer from the right ventricle to the pulmonary circulation. The gold standard measurement, end-systolic elastance/arterial elastance ratio (Ees/Ea), is derived from invasive pressure-volume loop, which is technically demanding, expensive and limited in clinical practice. Recent studies have proposed various non-invasive surrogates of Ees/Ea based on echocardiography assessment, of which TAPSE/PASP ratio is an easily-obtained and validated parameter in severe pulmonary hypertension and rapidly applicated in the diagnosis and risk evaluation of various diseases and cardiac intervention. In this review, we summarized principles and validations of echocardiographic surrogates, and their clinical utilities and also limitations. The goal is to systematically review the research advances of echocardiography assessment of RV-PA coupling and help to guide clinical practice.

Pathophysiology of the right ventricle in health and disease: an update

The contribution of the right ventricle (RV) to cardiac output is negligible in normal resting conditions when pressures in the pulmonary circulation are low. However, the RV becomes relevant in healthy subjects during exercise and definitely so in patients with increased pulmonary artery pressures both at rest and during exercise. The adaptation of RV function to loading rests basically on an increased contractility. This is assessed by RV end-systolic elastance (Ees) to match afterload assessed by arterial elastance (Ea). The system has reserve as the Ees/Ea ratio or its imaging surrogate ejection fraction has to decrease by more than half, before the RV undergoes an increase in dimensions with eventual increase in filling pressures and systemic congestion. RV-arterial uncoupling is accompanied by an increase in diastolic elastance. Measurements of RV systolic function but also of diastolic function predict outcome in any cause pulmonary hypertension and heart failure with or without preserved left ventricular ejection fraction. Pathobiological changes in the overloaded RV include a combination of myocardial fibre hypertrophy, fibrosis and capillary rarefaction, a titin phosphorylation-related displacement of myofibril tension-length relationships to higher pressures, a metabolic shift from mitochondrial free fatty acid oxidation to cytoplasmic glycolysis, toxic lipid accumulation, and activation of apoptotic and inflammatory signalling pathways. Treatment of RV failure rests on the relief of excessive loading.

Literature Review-Transthoracic Echocardiography, Computed Tomography Angiography, and Their Value in Clinical Decision Making and Outcome Predictions in Patients with COVID-19 Associated Cardiovascular Complications

The sudden outbreak of the COVID-19 pandemic posed a great threat to the world's healthcare systems. It resulted in the development of new methods and algorithms for the diagnosis and treatment of both COVID-19 and its complications. Diagnostic imaging played a crucial role in both cases. Among the most widely used examinations are transthoracic echocardiography (TTE) and computed tomography angiography (CTA). Cardiovascular complications in COVID-19 are frequently associated with a severe inflammatory response, which results in acute respiratory failure, further leading to severe complications of the cardiovascular system. Our review aims to discuss the value of TTE and CTA in clinical decision making and outcome prediction in patients with COVID-19-associated cardiovascular complications. Our review revealed the high clinical value of various TTE findings and their association with mortality and the prediction of patients' clinical outcomes, especially when used with other laboratory parameters. The strongest association between increased mortality and findings in TTE was observed for tachycardia and decreased left ventricular ejection fraction (odds ratio (OR) 24.06) and tricuspid annular plane systolic excursion/pulmonary artery systolic pressure ratio (TAPSE/PASP ratio) < 0.31 mm/mmHg (OR 17.80). CTA is a valuable tool in diagnosing COVID-19-associated pulmonary embolism, but its association with mortality and its predictive role should always be combined with laboratory findings and patients' medical history. D-dimers > 3000 ng/mL were found as the strongest predictors of pulmonary embolism (PE) (OR 7.494). Our review indicates the necessity for an active search for cardiovascular complications in patients with severe COVID-19, as they are linked with an increased probability of fatal outcomes.

Long-Term Effects of Sacubitril-Valsartan on Cardiac Remodeling: A Parallel Echocardiographic Study of Left and Right Heart Adaptive Response

Sacubitril/Valsartan (S/V) carries potential anti-remodeling properties, however long-term effects and biventricular adaptive response are poorly described. 76 HFrEF patients who underwent progressive uptitration of S/V, completed the annual scheduled follow-up. After a median follow-up of 11 (8-13) months, left ventricular (LV) reverse remodeling (RR) is defined as (1) absolute increase in LV ejection fraction (EF) ≥ 10% or LVEF ≥ 50% at follow-up and (2) decrease in indexed LV end-diastolic diameter (LVEDDi) of at least 10% or indexed LVEDDi ≤ 33 mm/m2, occurred in 27.6%. Non-ischemic etiology, shorter duration of HF, and absence of a history of AF were independently associated with LVRR (p < 0.05). TAPSE and TAPSE/PASP, a non-invasive index of right ventricular (RV) coupling to the pulmonary circulation, significantly improved at follow-up (0.45 vs. 0.56, p = 0.02). 41% of patients with baseline RV dysfunction obtained favorable RV remodeling despite only a moderate correlation between RV and LV function was observed (r = 0.478, p = 0.002). Our data point to a potential long-term reverse global remodeling effect by S/V, especially in patients who start S/V at an early stage of the disease, and focus our attention on a possible direct effect of the drug in synergistic hemodynamics between RV and pulmonary circulation.

The Potential of Thyroid Hormone Therapy in Severe COVID-19: Rationale and Preliminary Evidence

Tissue hypoxia is one of the main pathophysiologic mechanisms in sepsis and particularly in COVID-19. Microvascular dysfunction, endothelialitis and alterations in red blood cell hemorheology are all implicated in severe COVID-19 hypoxia and multiorgan dysfunction. Tissue hypoxia results in tissue injury and remodeling with re-emergence of fetal programming via hypoxia-inducible factor-1α (HIF-1a)-dependent and -independent pathways. In this context, thyroid hormone (TH), a critical regulator of organ maturation, may be of relevance in preventing fetal-like hypoxia-induced remodeling in COVID-19 sepsis. Acute triiodothyronine (T3) treatment can prevent cardiac remodeling and improve recovery of function in clinical settings of hypoxic injury as acute myocardial infarction and by-pass cardiac surgery. Furthermore, T3 administration prevents tissue hypoxia in experimental sepsis. On the basis of this evidence, the use of T3 treatment was proposed for ICU (Intensive Care Unit) COVID-19 patients (Thy-Support, NCT04348513). The rationale for T3 therapy in severe COVID-19 and preliminary experimental and clinical evidence are discussed in this review.