Hyperbaric Oxygenation Applied Immediately After Coronary Occlusion Reduces Myocardial Necrosis and Acute Mortality in Rats

Abstract

1. Because in ischaemia there is a critical lack of O2, it has been reasoned that increasing O2 delivery to the ischaemic myocardium could serve as adjunctive therapy for acute myocardial infarction (MI). Accordingly, in the present study, the effect of early hyperbaric oxygenation (HBO) on mortality and MI size after coronary occlusion was examined in rats. 2. After coronary occlusion, male Wistar rats were randomly assigned to receive either HBO for 1 h in a hyperbaric chamber (100% O(2) at 253 kPa; n = 106) or ambient O2 as the control (n = 111). The extent of myocardial necrosis was assessed (triphenyltetrazolium) immediately after treatment in the HBO (n = 50) and control (n = 47) groups. The remaining rats were evaluated 24 h after occlusion to enable calculation of MI size and mortality. 3. Immediately after therapy, the size of the MI was significantly greater in the control group compared with that in the HBO group (40 +/- 3 vs 27 +/- 2% of the left ventricle (LV), respectively; P < 0.001). The 24 h mortality of control rats was higher than that of HBO rats (34 vs 16%, respectively; P = 0.02). Control rats that survived 24 h had a larger MI than did HBO rats that survived 24 h (40 +/- 4 vs 29 +/- 3% of the LV, respectively; P = 0.005). Furthermore, large necrotic areas (> 40% of the LV) were more frequent in control than HBO rats (55 vs 27% of infarcted hearts, respectively; P = 0.01). There was less pulmonary congestion observed in HBO rats compared with control rats. 4. In conclusion, early therapy with HBO during the onset of an acute ischaemic event decreases the necrotic area and reduces acute mortality. These data support further investigation of HBO as an adjuvant therapy for acute MI.

Low Doses of Hyperbaric Oxygenation Effectively Decrease the Size of Necrotic Zone in Rats with Experimental Myocardial Infarction

“…Similar results were reported earlier [7]: the authors observed a decrease in the necrosis zone in the myocardium if HBO procedure was performed immediately after ischemia and then the rats were kept under standard conditions for 24 h. We suppose that the problem of HBO application in acute MI is at the stage of accumulation of experimental and clinical material. Heterogeneity of the experimental and clinical models and different variants of HBO application do not allow defi nite conclusions.…”

Gender-Based Differences in Cardiac Remodeling and ILK Expression after Myocardial Infarction

“…Six weeks after the surgical ligation of the coronary artery or sham operations, the animals were anesthetized as described above and measurements were performed using a 12-MHz transducer connected to a HP Sonos-5500 echocardiograph (Hewlett-Packard, California, USA) as previously described 14,15 . The MI size was measured by transversal 2-dimensional view of the left ventricle on the basal, midtransversal, and apical planes.…”

Características fisiopatológicas do modelo de insuficiência cardíaca pós-infarto do miocárdio no rato

“…Although it identifies the presence of an MI-dependent electrically inactive area, the ECG is not a method that can quantify the infarction area 2 . The echocardiogram can determine the presence and the size of the MI with very good sensitivity [3][4][5][6][7][8][9][10][11][12][13][14][15] , even in periods as early as two days after necrosis, and it also provides information about deviant atrial and ventricular function. The best method for post-mortem diagnosis of MI depends on the stage in which the autopsy occurs.…”

“…The electrocardiogram 2 and the echocardiogram [3][4][5][6][7][8][9][10][11][12][13][14][15] are noninvasive methods capable of identifying the area of necrosis or scarring. Although it identifies the presence of an MI-dependent electrically inactive area, the ECG is not a method that can quantify the infarction area 2 .…”