<p>Reperfusion Microvascular Ischemia After Prolonged Coronary Occlusion: Implications And Treatment With Local Supersaturated Oxygen Delivery</p>

Abstract

Following a prolonged coronary arterial occlusion, heterogeneously scattered, focal regions of low erythrocyte flow are commonly found throughout the reperfused myocardium. Experimental studies have also demonstrated the presence of widespread, focally patchy regions of microvascular ischemia during reperfusion (RMI). However, the potential contribution of RMI to tissue viability and function has received little attention in the absence of practical clinical methods for its detection. In this review, the anatomic/functional basis of RMI is summarized, along with the evidence for its presence in reperfused myocardium. Advances in microcirculation research related to obstructive responses of vascular endothelial cells and blood elements to the effects of hypoxia and low shear stress are discussed, and a potential cycle of intensification of RMI from such responses and progressive loss of functional capillary density is presented. In capillaries with impaired erythrocyte flow, compensatory increases in the delivery of oxygen, because of its low solubility in plasma, are effective only at high partial pressures. As discussed herein, attenuation of the cycle with oxygen at hyperbaric levels in plasma is, very likely, responsible for improved tissue level perfusion noted experimentally. Observed clinical benefits from intracoronary SuperSaturated oxygen (SSO2) delivery, including infarct size reduction, can be attributed to attenuation of RMI with improvement in microvascular blood flow.

Recent advances in the diagnosis and management of acute myocardial infarction

“…[20][21][22][23][24] Supersaturated oxygen (SSO 2 ) therapy shows potential for improving oxygenation and minimize infarction size. [25][26][27][28][29] Inflammation targeting methods after AMI have promising results in animal trials, and a randomized controlled trial (RCT) the Colchicine cardiovascular outcomes trial (the COLCOT trial) has demonstrated the beneficial effects of colchicine. [30][31][32][33][34][35][36][37] Targeting angiogenesis, using stem cells, biomaterials, and gene therapy, holds promise for regenerating myocardial tissue.…”

Update on Cardioprotective Strategies for STEMI

“…Intracoronary hyperoxemic perfusion was associated with less endothelial cell edema and preserved endothelial nuclei ( Figure 6 ). SSO 2 treatment also prevented myocardial apoptosis ( 41 , 46 ).

Figure 6 Electron Micrographs of Porcine Myocardium in Control and SSO 2 -Treated Pigs Electron micrographs of porcine myocardium at 3 hours of reperfusion after 1 hour of occlusion in a control pig (left) and SSO 2 -treated pig (right) .

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“…Spears ( 41 ) has reviewed the concept of patchy regions of residual microvascular ischemia that remain in the reperfused bed, even after establishing patency of the MI-related culprit epicardial coronary artery, and the mechanisms behind this phenomenon. Specifically, reperfusion is typically heterogeneous within the microvasculature, resulting in patchy areas of residual ischemia/hypoxia in the ischemic risk zone.…”

Hypoxemia in COVID-19 patients: An hypothesis

“…Another ray of hope comes from the demonstration that pulmonary hypertension induced by hypoxic ventilation in young calves can be reversed by infusion of supersaturated oxygen-carrying saline solution [41]. Additionally reperfusion microvascular injuries of the heart following 30-minute coronary occlusion were also reversed in similar experiments [42].…”