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The right ventricle (RV) and pulmonary arterial (PA) tree are inextricably linked, continually transferring energy back and forth in a process known as RV-PA coupling. Healthy organisms maintain this relationship in optimal balance by modulating RV contractility, pulmonary vascular resistance, and compliance to sustain RV-PA coupling through life's many physiologic challenges. Early in states of adaptation to cardiovascular disease-for example, in diastolic heart failure-RV-PA coupling is maintained via a multitude of cellular and mechanical transformations. However, with disease progression, these compensatory mechanisms fail and become maladaptive, leading to the often-fatal state of "uncoupling." Noninvasive imaging modalities, including echocardiography, magnetic resonance imaging, and computed tomography, allow us deeper insight into the state of coupling for an individual patient, providing for prognostication and potential intervention before uncoupling occurs. In this review, we discuss the physiologic foundations of RV-PA coupling, elaborate on the imaging techniques to qualify and quantify it, and correlate these fundamental principles with clinical scenarios in health and disease. © 2022 American Physiological Society. Compr Physiol 12: 1-26, 2022.

Obesity is now considered a primary comorbidity in heart failure with preserved ejection fraction (HFpEF) pathophysiology, mediated largely by systemic inflammation. Although there is accumulating evidence for a disease-related dysregulation of blood flow during exercise in this patient group, the role of obesity in the hemodynamic response to exercise remains largely unknown. Small muscle mass handgrip (HG) exercise was used to evaluate exercising muscle blood flow in nonobese (BMI < 30 kg/m(2), n = 14) and obese (BMI > 30 kg/m(2), n = 40) patients with HFpEF. Heart rate (HR), stroke index (SI), cardiac index (CI), mean arterial pressure (MAP), forearm blood flow (FBF), and vascular conductance (FVC) were assessed during progressive intermittent HG exercise [15%–30%–45% maximal voluntary contraction (MVC)]. Blood biomarkers of inflammation [C-reactive protein (CRP) and interleukin-6 (IL-6)] were also determined. Exercising FBF was reduced in obese patients with HFpEF at all work rates (15%: 304 ± 42 vs. 229 ± 15 mL/min; 30%: 402 ± 46 vs. 300 ± 18 mL/min; 45%: 484 ± 55 vs. 380 ± 23 mL/min, nonobese vs. obese, P = 0.025), and was negatively correlated with BMI (R = −0.47, P < 0.01). In contrast, no differences in central hemodynamics (HR, SI, CI, and MAP) were found between groups. Proinflammatory biomarkers were markedly elevated in patients with obesity (CRP: 2,133 ± 418 vs. 4,630 ± 590 ng/mL, P = 0.02; IL-6: 2.9 ± 0.3 vs. 5.2 ± 0.7 pg/mL, nonobese vs. obese, P = 0.04), and both biomarkers were positively correlated with BMI (CRP: R = 0.40, P = 0.03; IL-6: R = 0.57, P < 0.01). Together, these findings demonstrate the presence of obesity and an accompanying milieu of systemic inflammation as important factors in the dysregulation of exercising muscle blood flow in patients with HFpEF. NEW & NOTEWORTHY Obesity is the primary comorbid condition in HFpEF pathophysiology, but the role of adiposity on the peripheral circulation is not well understood. The present study identified a 30%–40% reduction in forearm blood flow during handgrip exercise, accompanied by a marked elevation in proinflammatory plasma biomarkers, in obese patients with HFpEF compared with their nonobese counterparts. These findings suggest an exaggerated dysregulation in exercising muscle blood flow associated with the obese HFpEF phenotype.

Pulmonary hypertension (PH) due to left heart disease (LHD; group 2 PH) is a common complication of heart failure with reduced ejection fraction and heart failure with preserved ejection fraction and is often related to disease severity and duration of these diseases. PH due to LHD is associated with negative impact on outcomes in addition to worse symptoms and exercise capacity. Risk factors for group 2 PH are older age, hypertension, atrial fibrillation, and features of metabolic syndrome. The main mechanisms for group 2 PH are believed to be vascular remodeling secondary to sustained elevated intravascular pressure.

Background Constrictive pericarditis (CP) is characterized by scarring and loss of elasticity of the pericardium. This case demonstrates that mixed martial arts (MMA) is a previously unrecognized risk factor for CP, diagnosis of which is supported by cardiac imaging, right and left heart catheterization, and histological findings of dense fibrous tissue without chronic inflammation. Case presentation A 47-year-old Caucasian male former mixed martial arts (MMA) fighter from the Western United States presented to liver clinic for elevated liver injury tests (LIT) and a 35-pound weight loss with associated diarrhea, lower extremity edema, dyspnea on exertion, and worsening fatigue over a period of 6 months. Past medical history includes concussion, right bundle branch block, migraine headache, hypertension, chronic pain related to musculoskeletal injuries and fractures secondary to MMA competition. Involvement in MMA was extensive with an 8-year history of professional MMA competition and 13-year history of MMA fighting with recurrent trauma to the chest wall. The patient also reported a 20-year history of performance enhancing drugs including testosterone. Physical exam was notable for elevated jugular venous pressure, hepatomegaly, and trace peripheral edema. An extensive workup was performed including laboratory studies, abdominal computerized tomography, liver biopsy, echocardiogram, and cardiac magnetic resonance imaging. Finally, right and left heart catheterization—the gold standard—confirmed discordance of the right ventricle-left ventricle, consistent with constrictive physiology. Pericardiectomy was performed with histologic evidence of chronic pericarditis. The patient’s hospital course was uncomplicated and he returned to NYHA functional class I. Conclusions CP can be a sequela of recurrent pericarditis or hemorrhagic effusions and may have a delayed presentation. In cases of recurrent trauma, CP may be managed with pericardiectomy with apparent good outcome. Further studies are warranted to analyze the occurrence of CP in MMA so as to better define the risk in such adults.

Background Since the initial description in the 1980s, our understanding of the diversity of pulmonary arterial hypertension (PAH) has continued to evolve. In this study, we report the characteristics of patients seen in an academic medical center for PAH from August 2020 through November 2021 and contrast those with nationally reported data from the United States Pulmonary Hypertension Scientific Registry (USPHSR). Study Design Investigators at the University of Utah Pulmonary Hypertension Program prospectively enrolled adult patients diagnosed with WHO Group 1 PAH, who were evaluated between August 2020 and November 2021 in a program-specific registry. Patient exposure and health histories were collected through structured interviews and questionnaires, along with clinical data and medication use. A total of 242 patients were enrolled in the University of Utah Pulmonary Hypertension Registry (UUPHR). Results Of the 242 enrolled patients, the most common etiology was associated PAH (APAH), accounting for 71.1% of the population. The second largest etiology was idiopathic PAH (IPAH) at 26.4%. The remaining patients were distributed between familial PAH (FPAH), pulmonary veno-occlusive disease (PVOD), and others. Of the total population classified as APAH, 39% of cases were noted as secondary to connective tissue disease (CTD) and 33% as toxin-induced. These represented 28% and 24% of the total population, respectively. Conclusions In this US-based accredited academic medical center, the etiology of PAH in our patient population contrasts with national registry data. In the UUPHR, APAH, specifically CTD-PAH and toxin-associated PAH, accounts for the majority of patients with PAH. This contrasts with IPAH, which nationally is the most reported cause of PAH. Differences in our population may reflect the regional variation of the referral site, but it is noteworthy for its contrast with historically reported phenotypes.