Exercise and pulsatile pulmonary vascular loading in chronic thromboembolic pulmonary disease

Chronic thromboembolic pulmonary disease (CTEPD) is characterized by organized nonresolving thrombi in pulmonary arteries (PA). In CTEPD with pulmonary hypertension (PH), chronic thromboembolic PH (CTEPH), early wave reflection results in abnormalities of pulsatile afterload and augmented PA pressures. We hypothesized that exercise during right heart catheterization (RHC) would elicit more frequent elevations of pulsatile vascular afterload than resistive elevations in patients with CTEPD without PH. The interdependent physiology of pulmonary venous and PA hemodynamics was also evaluated. Consecutive patients with CTEPD without PH (resting mean PA pressure ≤20 mmHg) undergoing an exercise RHC were identified. Latent resistive and pulsatile abnormalities of pulmonary vascular afterload were defined as an exercise mean PA pressure/cardiac output >3 WU, and PA pulse pressure to PA wedge pressure (PA PP/PAWP) ratio >2.5, respectively. Forty-five patients (29% female, 53 ± 14 years) with CTEPD without PH were analyzed. With exercise, 19 patients had no abnormalities (ExNOR), 26 patients had abnormalities (ExABN) of pulsatile (20), resistive (2), or both (4) elements of pulmonary vascular afterload. Exercise elicited elevations of pulsatile afterload (53%) more commonly than resistive afterload (13%) (p < 0.001). ExABN patients had lower PA compliance and higher pulmonary vascular resistance at rest and exercise and prolonged resistance-compliance time product at rest. The physiological relationship between changes in PA pressures relative to PAWP was disrupted in the ExABN group. In CTEPD without PH, exercise RHC revealed latent pulmonary vascular afterload elevations in 58% of patients with more frequent augmentation of pulsatile than resistive pulmonary vascular afterload.

Dysregulated autoantibodies targeting vaso- and immunoregulatory receptors in Post COVID Syndrome correlate with symptom severity

Most patients with Post COVID Syndrome (PCS) present with a plethora of symptoms without clear evidence of organ dysfunction. A subset of them fulfills diagnostic criteria of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Symptom severity of ME/CFS correlates with natural regulatory autoantibody (AAB) levels targeting several G-protein coupled receptors (GPCR). In this exploratory study, we analyzed serum AAB levels against vaso- and immunoregulatory receptors, mostly GPCRs, in 80 PCS patients following mild-to-moderate COVID-19, with 40 of them fulfilling diagnostic criteria of ME/CFS. Healthy seronegative (n=38) and asymptomatic post COVID-19 controls (n=40) were also included in the study as control groups. We found lower levels for various AABs in PCS compared to at least one control group, accompanied by alterations in the correlations among AABs. Classification using random forest indicated AABs targeting ADRB2, STAB1, and ADRA2A as the strongest classifiers (AABs stratifying patients according to disease outcomes) of post COVID-19 outcomes. Several AABs correlated with symptom severity in PCS groups. Remarkably, severity of fatigue and vasomotor symptoms were associated with ADRB2 AAB levels in PCS/ME/CFS patients. Our study identified dysregulation of AAB against various receptors involved in the autonomous nervous system (ANS), vaso-, and immunoregulation and their correlation with symptom severity, pointing to their role in the pathogenesis of PCS.