A Dynamic Sheep Model to Induce Pulmonary Hypertension and Right Ventricular Failure.

Decompensated right ventricular failure (RVF) in pulmonary hypertension (PH) is fatal, with limited medical treatment options. Developing and testing novel therapeutics for PH requires a clinically relevant large animal model of increased pulmonary vascular resistance and RVF. This manuscript describes the method to induce an ovine PH-RVF model that utilizes left pulmonary artery (LPA) ligation, progressive main pulmonary artery (MPA) banding, and insertion of an RV pressure line for monitoring. The PA cuff and RV pressure tubing are connected to subcutaneous access ports. This model of PH-RVF is a versatile platform to control not only the disease severity, but also the RV's phenotypic response. Subjects undergo progressive PA band adjustments twice per week for approximately 9 weeks with sequential measures of RV pressure, PA cuff pressures, and mixed venous blood gas (SvO2). Subjects can further be exercised on a livestock treadmill while hemodynamic parameters are captured. At the initiation and endpoint of this model, ventricular function and dimensions are assessed using echocardiography. In this model, RV mean and systolic pressure increased to 28 ± 5 and 57 ± 7 mmHg at week 1, and further to 44 ± 7 and 93 ± 18 mmHg by week 9, respectively. Echocardiography demonstrates characteristic findings of PH-RVF, notably RV dilation, increased wall thickness, and septal bowing. The rate of PA banding has a significant impact on SvO2 and thus the model can be titrated to elicit varying RV phenotypes. When the PA cuff is tightened rapidly, it can lead to a precipitous decline in SvO2, leading to RV decompensation, whereas a slower, more paced strategy leads to an adaptive RV stress-load response that maintains physiologic SvO2. A faster rate of PA banding will also lead to more severe liver fibrosis. The addition of controlled exercise provides a useful platform for assessing the effects of physical exertion in a PH-RVF model. This chronic PH-RVF model provides a valuable tool for studying molecular mechanisms, developing diagnostic biomarkers, and evaluating mechanical circulatory support systems.

Human immunodeficiency virus infection is associated with greater risk of pneumonia and readmission after cardiac surgery.

Objective: Human immunodeficiency virus infection (HIV+) is associated with a 2-fold increased risk of cardiovascular disease. Increasingly, patients who are HIV + are being evaluated to undergo cardiac surgery. Current risk-adjusted scoring systems, including the Society of Thoracic Surgeons Predicted Risk of Mortality score, fail to stratify HIV + risk. Unfortunately, there exists a paucity of cardiac surgery outcomes data in modern patients who are HIV+. Methods: We conducted a retrospective review of PearlDiver, an all-payer claims administrative database. In total, 14,714,743 patients were captured between 2010 and 2020. Of these, 59,695 (0.4%) of patients had a history of HIV+, and 1759 (2.95%) of these patients underwent cardiac surgery. Patients who were HIV+ were younger, more often male, and had greater comorbidity, history of hypertension, chronic obstructive pulmonary disease, chronic liver disease, chronic kidney disease, chronic lung disease, and heart failure. Results: Postoperatively, patients who were HIV + had significantly greater rates of pneumonia (relative risk, 1.70; P = .0003) and 30-day all-cause readmission (relative risk, 1.28, P < .0001). After linear regression analysis, these results remained significant. Data also show that a lesser proportion of patients with HIV + underwent coronary artery bypass grafting, aortic valve replacement, and any cardiac surgery compared with controls. Conclusions: Patients who are HIV + undergoing cardiac surgery are at greater risk of pneumonia and readmission. Moreover, we discovered lower rates of cardiac surgery in patients who are HIV+, which may reflect limited access to surgery when indicated. Today's risk-adjusted scoring systems in cardiac surgery need to better account for the modern patient who is HIV+.