Predicting Hemodynamic Changes During Intra-Aortic Balloon Pump Support With a Longitudinal Evaluation

The use of intra-aortic balloon pump (IABP) has decreased in recent years due to negative outcome studies in cardiogenic shock complicating acute myocardial infarction, despite its favorable adverse-event profile. Acute hemodynamic response studies have identified potential super-responders with immediate improvements in cardiac index (CI) in heart failure patients. This single-center retrospective study aimed to predict CI and mean arterial pressure (MAP) changes throughout the entire duration of IABP support. The study analyzed 336 patients who received IABP between 2016 and 2022. Linear mixed-effect regression models were used to predict CI and MAP improvement during IABP support. The results showed that CI and MAP increases during the first days of support, and changes during IABP support varied with time and were associated with baseline parameters. Longitudinal CI change was associated with body surface area, baseline CI, baseline pulmonary artery pulsatility index, baseline need for pressors, and diabetes. Longitudinal MAP change was associated with baseline MAP, baseline heart rate, need for pressors, or inotropes. The study recommends considering these parameters when deciding if IABP is the most appropriate form of support for a specific patient. Further prospective studies are needed to validate the findings.

A Large Cyst in an Unlikely Location: The Interventricular Septum

•A large cardiac cyst was discovered in an extremely rare location: the IVS. •Pre- and postcontrast imaging is essential in the evaluation of a cystic mass. •When identifying a cardiac cyst, malignancy and infection must be considered. •The benefit of excising a cardiac cyst is unclear in an asymptomatic older patient.

Probe Confined Dynamic Mapping for G Protein-Coupled Receptor Allosteric Site Prediction

Targeting G protein-coupled receptors (GPCRs) through allosteric sites offers advantages over orthosteric sites in identifying drugs with increased selectivity and potentially reduced side effects. In this study, we developed a probe confined dynamic mapping protocol that allows the prediction of allosteric sites at both the GPCR extracellular and intracellular sides, as well as at the receptor-lipid interface. The applied harmonic wall potential enhanced sampling of probe molecules in a selected area of a GPCR while preventing membrane distortion in molecular dynamics simulations. The specific probes derived from GPCR allosteric ligand structures performed better in allosteric site mapping compared to commonly used cosolvents. The M₂ muscarinic, β₂ adrenergic, and P₂Y₁ purinergic receptors were selected for the protocol's retrospective validation. The protocol was next validated prospectively to locate the binding site of [5-fluoro-4-(hydroxymethyl)-2-methoxyphenyl]-(4-fluoro-1H-indol-1-yl)methanone at the D₂ dopamine receptor, and subsequent mutagenesis confirmed the prediction. The protocol provides fast and efficient prediction of key amino acid residues surrounding allosteric sites in membrane proteins and facilitates the structure-based design of allosteric modulators.