Efficacy of Intravenous Iron in Patients with Heart Failure with Reduced Ejection Fraction and Iron Deficiency: A Systematic Review and Meta-Analysis of Randomized Control Trials.

BACKGROUND: The European Society of Cardiology (ESC) provided a focused update to the 2021 Guideline for the Management of Heart Failure, now providing a 1A recommendation for intravenous iron in patients with heart failure with reduced ejection fraction (HFrEF) and iron deficiency (ID). However, the findings from randomized controlled trials (RCT) are mixed. This systematic review of RCTs aims to provide an update and synthesize the evidence addressing the association of intravenous iron with patient-based outcomes in patients with HFrEF and ID. METHODS: Any RCT evaluating the effect of intravenous iron in patients with HFrEF and ID was eligible for inclusion. A complete search of the EMBASE and PubMed databases was conducted from inception until 15 September 2023. The primary outcome was the composite of the quality of life (QoL) questionnaires, while the secondary outcomes included first heart failure (HF) hospitalizations and all-cause mortality. Data extraction was performed independently by two reviewers. Data were pooled using a random-effects model. RESULTS: Of the 1035 references, 15 RCTs enrolling 6649 patients were included in this study. Intravenous iron was associated with significant improvement in the composite of QoL (standardized mean difference - 1.36, 95% confidence interval [CI] - 2.24 to - 0.48; p = 0.002), a significant reduction in first HF hospitalizations (hazard ratio [HR] 0.73, 95% CI 0.56-0.95; p = 0.02), and with no change in all-cause mortality (HR 0.90, 95% CI 0.79-1.03; p = 0.12). The certainty of the evidence ranged from moderate to very low. CONCLUSION: Intravenous iron is possibly associated with improved QoL and reduced HF hospitalizations, without impacting all-cause mortality. These findings not only support the use of intravenous iron in patients with HFrEF but also emphasize the need for well-designed and executed RCTs with granular outcome reporting and powered sufficiently to address the impact of intravenous iron on mortality in patients with HFrEF and ID. REGISTRATION: PROSPERO identifier number CRD42023389.

Pulmonary hypertension and congenital bronchial atresia: A time factor association.

Congenital bronchial atresia is rarely symptomatic in adults. Recurrent lung infection and pneumothorax are the feared complications of this otherwise benign condition. The objective of this article is to present a case of congenital bronchial atresia manifesting as pulmonary hypertension in a 66 year-old patient. While doing so, we highlight the relevant knowledge accrued in medical literature with regards this rare condition. Finally, with the revelation that congenital bronchial atresia may cause severe pulmonary hypertension later in life, perhaps a less conservative approach to management may be warranted in younger adults and children with this condition.

Regional disparity in outcomes among patients hospitalized for Takotsubo cardiomyopathy in the United States✰.

INTRODUCTION: Takotsubo cardiomyopathy (TTCM), an entity first described in Japan over two decades ago following myocardial stunning cases without evidence of coronary stenosis, has emerged as a unique entity with global recognition. We sought to investigate the extent and magnitude of regional variations in its outcomes. METHOD: We used the National Inpatient Sample (NIS) of the Agency for Healthcare Research and Quality (2010-2014). Risk-adjusted rates of outcomes across the US geographical regions were calculated by fitting a Poisson regression model with a robust error variance under generalized estimating equations. Discrete numeric variables with over-dispersed count distributions -length of stay and continuous variables with a right skewed spread- cost of hospitalization were modeled using a generalized linear regression with a negative binomial function and gamma function respectively. RESULT: We found significant regional variations in-patient mortality. While there was significantly higher risk of in-hospital death in the West (5.28 [4.34-6.44]) vs 4.40 [3.57-5.43] vs 4.10 [3.38-498] vs 4.78 [3.96-5.77]), there was a different pattern of variation in the length of days with longer hospital stay in the Northeast. Likewise, the risk-adjusted rate of non-routine home discharges was highest for Northeast. The West had the highest cost of hospitalization (West: $40,217 vs. South: $28,465) CONCLUSION: Significant geographic variation exists in the cost of hospitalization and in-hospital mortality of TTCM across the US. Understanding this variation requires a detailed understanding of the processes of care and identification of effective strategies to eliminate these disparities.

TRPM4 channels couple purinergic receptor mechanoactivation and myogenic tone development in cerebral parenchymal arterioles.

Cerebral parenchymal arterioles (PAs) have a critical role in assuring appropriate blood flow and perfusion pressure within the brain. They are unique in contrast to upstream pial arteries, as defined by their critical roles in neurovascular coupling, distinct sensitivities to chemical stimulants, and enhanced myogenic tone development. The objective of the present study was to reveal some of the unique mechanisms of myogenic tone regulation in the cerebral microcirculation. Here, we report that in vivo suppression of TRPM4 (transient receptor potential) channel expression, or inhibition of TRPM4 channels with 9-phenanthrol substantially reduced myogenic tone of isolated PAs, supporting a key role of TRPM4 channels in PA myogenic tone development. Further, downregulation of TRPM4 channels inhibited vasoconstriction induced by the specific P2Y4 and P2Y6 receptor ligands (UTPγS and UDP) by 37% and 42%, respectively. In addition, 9-phenanthrol substantially attenuated purinergic ligand-induced membrane depolarization and constriction of PAs, and inhibited ligand-evoked TRPM4 channel activation in isolated PA myocytes. In concert with our previous work showing the essential contributions of P2Y4 and P2Y6 receptors to myogenic regulation of PAs, the current results point to TRPM4 channels as an important link between mechanosensitive P2Y receptor activation and myogenic constriction of cerebral PAs.

Postischemic reperfusion causes smooth muscle calcium sensitization and vasoconstriction of parenchymal arterioles.

BACKGROUND AND PURPOSE: Parenchymal arterioles (PAs) are high-resistance vessels in the brain that connect pial vessels to the microcirculation. We previously showed that PAs have increased vasoconstriction after ischemia and reperfusion that could increase perfusion deficit. Here, we investigated underlying mechanisms by which early postischemic reperfusion causes increased vasoconstriction of PAs. METHODS: Isolated and pressurized PAs from within the middle cerebral artery territory were studied in male Wistar rats that were either nonischemic control (n=34) or after exposure to transient middle cerebral artery occlusion (MCAO) by filament occlusion for 2 hours with 30 minutes of reperfusion (MCAO; n=38). The relationships among pressure-induced tone, smooth muscle calcium (using Fura 2), and membrane potential were determined. Sensitivity of the contractile apparatus to calcium was measured in permeabilized arterioles using Staphylococcus aureus α-toxin. Reactivity to inhibition of transient receptor potential melastanin receptor type 4 (9-phenanthrol), Rho kinase (Y27632), and protein kinase C (Gö6976) was also measured. RESULTS: After MCAO, PAs had increased myogenic tone compared with controls (47±2% versus 35±2% at 40 mm Hg; P<0.01), without an increase in smooth muscle calcium (177±21 versus 201±16 nmol/L; P>0.05) or membrane depolarization (-38±4 versus -36±1 mV; P>0.05). In α-toxin-permeabilized vessels, MCAO caused increased sensitivity of the contractile apparatus to calcium. MCAO did not affect dilation to transient receptor potential melastanin receptor type 4 or protein kinase C inhibition but diminished dilation to Rho kinase inhibition. CONCLUSIONS: The increased vasoconstriction of PAs during early postischemic reperfusion seems to be due to calcium sensitization of smooth muscle and could contribute to infarct expansion and limit neuroprotective agents from reaching their target tissue.

Increased pressure-induced tone in rat parenchymal arterioles vs. middle cerebral arteries: role of ion channels and calcium sensitivity.

Brain parenchymal arterioles (PAs) are high-resistance vessels that branch off pial arteries and perfuse the brain parenchyma. PAs are the target of cerebral small vessel disease and have been shown to have greater pressure-induced tone at lower pressures than pial arteries. We investigated mechanisms by which brain PAs have increased myogenic tone compared with middle cerebral arteries (MCAs), focusing on differences in vascular smooth muscle (VSM) calcium and ion channel function. The amount of myogenic tone and VSM calcium was measured using Fura 2 in isolated and pressurized PAs and MCAs. Increases in intraluminal pressure caused larger increases in tone and cytosolic calcium in PAs compared with MCAs. At 50 mmHg, myogenic tone was 37 ± 5% for PAs vs. 6.5 ± 4% for MCAs (P < 0.01), and VSM calcium was 200 ± 20 nmol/l in PAs vs. 104 ± 15 nmol/l in MCAs (P < 0.01). In vessels permeabilized with Staphylococcus aureus α-toxin, PAs were not more sensitive to calcium, suggesting calcium sensitization was not at the level of the contractile apparatus. PAs were 30-fold more sensitive to the voltage-dependent calcium channel (VDCC) inhibitor nifedipine than MCAs (EC50 for PAs was 3.5 ± 0.4 vs. 82.1 ± 2.1 nmol/l for MCAs;P < 0.01); however, electrophysiological properties of the VDCC were not different in VSM. PAs had little to no response to the calcium-activated potassium channel inhibitor iberiotoxin, whereas MCAs constricted ∼15%. Thus increased myogenic tone in PAs appears related to differences in ion channel activity that promotes VSM membrane depolarization but not to a direct sensitization of the contractile apparatus to calcium.

Purinergic receptors regulate myogenic tone in cerebral parenchymal arterioles.

Myogenic tone is a fundamental aspect of vascular behavior in resistance arteries. This contractile response to changes in intravascular pressure is critically involved in blood flow autoregulation in tissues such as the brain, kidneys, and heart. Myogenic tone also helps regulate precapillary pressure and provides a level of background tone upon which vasodilator stimuli act to increase tissue perfusion when appropriate. Despite the importance of these processes in the brain, little is known about the mechanisms involved in control of myogenic tone in the cerebral microcirculation. Here, we report that pharmacological inhibition of P2Y4 and P2Y6 pyrimidine receptors nearly abolished myogenic tone in cerebral parenchymal arterioles (PAs). Molecular suppression of either P2Y4 or P2Y6 receptors using antisense oligodeoxynucleotides reduced myogenic tone by 44%±8% and 45%±7%, respectively. These results indicate that both receptor isoforms are activated by increased intravascular pressure, which enhances the activity of voltage-dependent calcium channels and increases myogenic tone in PAs. Enhancement or inhibition of ectonucleotidase activity had no effect on parenchymal arteriolar myogenic tone, indicating that this response is not mediated by local release of nucleotides, but rather may involve direct mechanical activation of P2Y receptors in the smooth muscle cells.

TRPV4-dependent dilation of peripheral resistance arteries influences arterial pressure.

Transient receptor potential vanilloid 4 (TRPV4) channels have been implicated as mediators of calcium influx in both endothelial and vascular smooth muscle cells and are potentially important modulators of vascular tone. However, very little is known about the functional roles of TRPV4 in the resistance vasculature or how these channels influence hemodynamic properties. In the present study, we examined arterial vasomotor activity in vitro and recorded blood pressure dynamics in vivo using TRPV4 knockout (KO) mice. Acetylcholine-induced hyperpolarization and vasodilation were reduced by approximately 75% in mesenteric resistance arteries from TRPV4 KO versus wild-type (WT) mice. Furthermore, 11,12-epoxyeicosatrienoic acid (EET), a putative endothelium-derived hyperpolarizing factor, activated a TRPV4-like cation current and hyperpolarized the membrane of vascular smooth muscle cells, resulting in the dilation of mesenteric arteries from WT mice. In contrast, 11,12-EET had no effect on membrane potential, diameter, or ionic currents in the mesenteric arteries from TRPV4 KO mice. A disruption of the endothelium reduced 11,12-EET-induced hyperpolarization and vasodilatation by approximately 50%. A similar inhibition of these responses was observed following the block of endothelial (small and intermediate conductance) or smooth muscle (large conductance) K(+) channels, suggesting a link between 11,12-EET activity, TRPV4, and K(+) channels in endothelial and smooth muscle cells. Finally, we found that hypertension induced by the inhibition of nitric oxide synthase was greater in TRPV4 KO compared with WT mice. These results support the conclusion that both endothelial and smooth muscle TRPV4 channels are critically involved in the vasodilation of mesenteric arteries in response to endothelial-derived factors and suggest that in vivo this mechanism opposes the effects of hypertensive stimuli.