Endothelin A and B receptor antagonist bosentan reduces postischemic myocardial injury in the rat: critical timing of administration

An Update on Systemic Sclerosis and its Perioperative Management

Purpose of Review

Systemic sclerosis or scleroderma (SSc) is a systemic, immune-mediated disease characterized by abnormal cutaneous and organ-based fibrosis that results in progressive end-organ dysfunction and decreased survival. SSc results in significant challenges for the practicing anesthesiologist due to its rarity, multi-system involvement, and limited evidence-based guidance for optimal perioperative care. In this update, we briefly discuss the recent evidence on the pathophysiology and current management of SSc, review the anesthesia-related literature, and extrapolate these observations into an optimal perioperative strategy for the care of SSc patients.

Recent Findings

Evidence shows that patients with SSc demonstrate an increased risk for perioperative myocardial infarction, high rates of interstitial lung disease, pulmonary arterial hypertension, neurological disease, gastric dysmotility disorders, and challenging airway management, all findings that may result in suboptimal perioperative outcomes.

Summary

Advances in SSc medical management have resulted in improved survival, likely increasing the number of patients who will be exposed to perioperative care. Optimal perioperative management and risk stratification should expand beyond the well-described airway challenges and consider numerous systemic manifestations of systemic sclerosis such as pulmonary arterial hypertension, interstitial lung disease, and cardiac sequelae.

Myocardial protective effect of tezosentan, an endothelin receptor antagonist, for ischemia-reperfusion injury in experimental heart failure models

The myocardial protective effects of endothelin antagonist in ischemic cardiomyopathy (ICMP), doxorubicin-induced cardiomyopathy (DOX) and pressure-overload hypertrophy by transverse aortic constriction (TAC) models have been predicted to be different. The objective of this experiment, therefore, is to evaluate the myocardial protective effect of tezosentan, an endothelin receptor antagonist, in various experimental heart failure models. Sprague-Dawley rats (6-8 weeks old, 200-300 g) were randomized to three experimental groups (n=30 each): ICMP; DOX; and TAC group. Each of these groups was randomly assigned further to the following subgroups (n=10 each): sham-operated ischemia-reperfusion subgroup (SHAM); tezosentan treated ischemia-reperfusion subgroup (Tezo); and tezosentan non-treated ischemia-reperfusion subgroup (N-Tezo). Total circulatory arrest was induced for 1 hr, followed by 2 hr of reperfusion. The left ventricular developed pressure, peak positive and negative first derivatives, and coronary blood flow were significantly different (P<0.05) among the SHAM, Tezo, and N-Tezo subgroups of the ICMP group at 30 min of reperfusion, but there were no statistically significant differences among the subgroups of the DOX and TAC groups. In conclusion, tezosentan, an endothelin receptor antagonist, showed myocardial protection effects only on the ischemic cardiomyopathy rat model, but not in the non-ischemic heart failure rat models.

Heart Preservation Using Continuous Ex Vivo Perfusion Improves Viability and Functional Recovery

BACKGROUND

Cold static storage (CS) is a proven preservation method for heart transplantion, yet early postoperative graft dysfunction remains prevalent, so continuous perfusion (CP) during ex vivo transport may improve viability and function of heart grafts.

METHODS AND RESULTS

Canine hearts underwent CP (n=9) or CS (n=9) for 6 h while intramyocardial pH was continuously monitored. Biopsies were assayed for ATP, caspase-3, malondialdehyde (MDA), and endothelin-1 (ET-1) levels at baseline, after preservation (t1), and after 1 h of blood reperfusion on a Langendorff model (t2). Functional recovery was determined at t2 by +dP/dt, -dP/dt, developed pressure, peak pressure and end-diastolic pressure. CP resulted in higher tissue pH and ATP stores and reduced caspase-3, MDA and ET-1 levels compared with CS at both t1 and t2. Post reperfusion recovery was significantly greater in CP vs CS for all myocardial functional parameters except end-diastolic pressure. Weight gain was significantly increased in CP vs CS at t1, but not at t2.

CONCLUSIONS

Low-grade tissue acidosis and energy depletion occur during CS and are associated with oxidative injury and apoptosis during reperfusion. CP attenuates these biochemical and pathologic manifestations of tissue injury, together with improved myocardial recovery, despite mild, transient edema.

15-F2t-isoprostane exacerbates myocardial ischemia-reperfusion injury of isolated rat hearts

Reactive oxygen species induce formation of 15-F2t-isoprostane (15-F2t-IsoP), a specific marker of in vivo lipid peroxidation, which is increased after myocardial ischemia and during the subsequent reperfusion. 15-F2t-IsoP possesses potent bioactivity under pathophysiological conditions. However, it remains unknown whether 15-F2t-IsoP, by itself, can influence myocardial ischemia-reperfusion injury (IRI). Adult rat hearts were perfused by the Langendorff technique with Krebs-Henseleit (KH) solution at a constant flow rate of 10 ml/min. 15-F2t-IsoP (100 nM), SQ-29548 (1 μM, SQ), a thromboxane receptor antagonist that can abolish the vasoconstrictor effect of 15-F2t-IsoP, 15-F2t-IsoP + SQ in KH, or KH alone (vehicle control) was applied for 10 min before induction of 40 min of global ischemia followed by 60 min of reperfusion. During ischemia, saline (control), 15-F2t-IsoP, 15-F2t-IsoP + SQ, or SQ in saline was perfused through the aorta at 60 μl/min. 15-F2t-IsoP, 15-F2t-IsoP + SQ, or SQ in KH was infused during the first 15 min of reperfusion. Coronary effluent endothelin-1 concentrations were significantly higher in the group treated with 15-F2t-IsoP than in the control group during ischemia and also in the later phase of reperfusion ( P < 0.05). Infusion of 15-F2t-IsoP increased release of cardiac-specific creatine kinase, reduced cardiac contractility during reperfusion, and increased myocardial infarct size relative to the control group. SQ abolished the deleterious effects of 15-F2t-IsoP. 15-F2t-IsoP exacerbates myocardial IRI and may, therefore, act as a mediator of IRI. 15-F2t-IsoP-induced endothelin-1 production during cardiac reperfusion may represent a mechanism underlying the deleterious actions of 15-F2t-IsoP.