Effect of superoxide dismutase and catalase on regional dysfunction after exercise-induced ischemia

This study was designed to test the hypothesis that the oxygen free radical scavengers superoxide dismutase (SOD) and catalase may reduce myocardial “stunning” after exercise-induced ischemia. To test this hypothesis, 8 mongrel dogs performed treadmill exercise for 10 min in the presence of a flow-limiting coronary artery stenosis. Regional left ventricular function was measured with ultrasonic microcrystals implanted to measure regional wall thickening. Regional myocardial perfusion was measured with radioactive microspheres. The combination of SOD (5 mg/kg iv) and catalase (5 mg/kg iv) did not affect heart rate, blood pressure, coronary artery flow, or regional myocardial blood flow at rest, during exercise, or in the postexercise period. SOD and catalase had no effect on regional wall thickening at rest before exercise. During exercise in the absence of a coronary artery stenosis, thickening was slightly lower during SOD and catalase infusion (27 +/- 11.0 vs. 30.8 +/- 11.5%, SOD vs. control P = 0.05). During exercise in the presence of a coronary artery stenosis, there was no difference in thickening. Infusion of SOD and catalase affected neither the transient rebound function occurring early after exercise nor the prolonged period of stunning. These results indicate that the myocardial stunning that follows exercise-induced ischemia is unlikely to be mediated by oxygen free radicals.

Download Full-text

Myocardial stunning in exercise-induced ischemia in dogs: lack of late preconditioning

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.2001.280.1.h302 ◽

2001 ◽

Vol 280 (1) ◽

pp. H302-H310 ◽

Cited By ~ 5

Author(s):

Olivier Parent De Curzon ◽

Bijan Ghaleh ◽

Renaud Tissier ◽

Jean-François Giudicelli ◽

Luc Hittinger ◽

...

Keyword(s):

Blood Flow ◽

Coronary Artery ◽

Myocardial Stunning ◽

Time Course ◽

Reactive Hyperemia ◽

Coronary Artery Occlusion ◽

Left Ventricular ◽

Wall Thickening ◽

Late Preconditioning ◽

Exercise Induced

Late preconditioning (PC) against myocardial stunning develops after coronary artery occlusion (CAO) at rest and subsequent reperfusion. We investigated whether late PC occurs after exercise-induced ischemia (high-flow ischemia) in dogs. A circumflex coronary artery stenosis (by using occluders) was set up before the onset of treadmill exercise in nine chronically instrumented dogs to suppress exercise-induced increase in mean coronary blood flow velocity (CBFV, Doppler) without simultaneously affecting left ventricular (LV) wall thickening (Wth) at rest. Two similar exercises were performed 24 h apart. On day 1, LV Wth was reduced by 84 ± 5% ( P < 0.01), and exercise-induced increases in transmural myocardial blood flow (MBF, fluorescent microspheres) in the ischemic zone were blunted. LV Wth was depressed throughout the first 10 h and returned to its baseline value after 24 h. On day 2, changes in LV Wth and MBF were similar as was the time course for LV Wth recovery, indicating lack of late PC. Also, CBFV responses to acetylcholine, nitroglycerin, and reactive hyperemia (20-s CAO) were not significantly different on days 1 and 2. Similar results were obtained in a subgroup of four additional dogs with more severe stenosis during exercise. Late PC against myocardial stunning was confirmed to occur in a model of 10-min CAO followed by coronary artery reperfusion (CAR) in another four dogs. Thus in contrast with CAO at rest followed by CAR, severe myocardial ischemia in coronary flow-limited exercising dogs does not induce late PC against myocardial stunning.

Download Full-text

Effects of beta-blockade on regional myocardial flow and function during exercise

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1984.247.1.h52 ◽

1984 ◽

Vol 247 (1) ◽

pp. H52-H60 ◽

Cited By ~ 5

Author(s):

M. Matsuzaki ◽

J. Patritti ◽

T. Tajimi ◽

M. Miller ◽

W. S. Kemper ◽

...

Keyword(s):

Coronary Artery ◽

Myocardial Dysfunction ◽

Left Ventricular Pressure ◽

Left Ventricular ◽

Beta Blockade ◽

Wall Thickening ◽

Ischemic Area ◽

Ischemic Region ◽

Exercise Induced ◽

Control Exercise

We examined the effects of a cardioselective beta-blocking drug on exercise-induced regional myocardial ischemia in 10 conscious dogs with chronic coronary artery stenosis. An ameroid constrictor, Doppler flowprobe, and hydraulic cuff were placed around the left circumflex coronary artery, and left ventricular pressure (LVP), systolic wall thickening (% delta WT; by sonomicrometry), and myocardial blood flow (MBF; microspheres) were measured during control standing, control treadmill exercise, and identical exercise after atenolol (1 mg/kg po). Prior to study, in every dog % delta WT and MBF in the ischemic area were normal at rest, indicating collateral development. During control exercise, % delta WT in the ischemic region markedly decreased from 27 to 4%, and transmural ischemia was evident in that region. Heart rate, systolic LVP, and LV (+)dP/dt were significantly lower during exercise after atenolol than during control exercise. % delta WT in the normal area was only 81% of that during control exercise, but dysfunction in the ischemic area was improved (77% increase compared with control exercise). Accompanying the improved function was a significant increase of MBF/beat and relative MBF in the ischemic zone; the endocardial-to-epicardial ratio increased from 0.27 to 0.47. Thus atenolol improved regional MBF distribution, thereby diminishing exercise-induced regional myocardial dysfunction and accelerating its recovery.

Download Full-text

Cardiovascular risk profiles and stress echocardiography results in patients with hypertensive response to exercise

Russian Journal of Cardiology ◽

10.15829/1560-4071-2021-4183 ◽

2021 ◽

Vol 26 (5) ◽

pp. 4183

Author(s):

E. A. Karev ◽

E. G. Malev ◽

A. Yu. Suvorov ◽

S. L. Verbilo ◽

M. N. Prokudina

Keyword(s):

Cardiovascular Risk ◽

Coronary Artery ◽

Stress Echocardiography ◽

Coronary Artery Stenosis ◽

Left Ventricular ◽

Artery Stenosis ◽

Exercise Stress ◽

Volume Index ◽

High Cardiovascular Risk ◽

Response To Exercise

Aim. To compare markers of high cardiovascular risk and stress echocardiography results depending on the type of blood pressure (BP) response to exercise in patients without obstructive coronary artery disease.Material and methods. Our single-center cross-sectional study included 96 patients without hemodynamically significant coronary artery stenosis according to coronary angiography or multislice computed tomography angiography. All patients underwent physical examination, cardiovascular risk stratification, electrocardiography, extracranial cerebrovascular ultrasound, echocardiography, treadmill exercise stress echocardiography.Results. According to the test results, the patients were divided into groups with a hypertensive response (n=41) and a normal response to exercise (n=55). Patients with hypertensive response to exercise had significantly higher values of left ventricular mass index (100,0 (90,0; 107,0) g/m2 vs 76,0 (68,0; 91,0) g/m2, p<0,0000001) and left atrial volume index (36,7 (32,0; 46,0) ml/m2 vs 29,7 (26,3; 32,0) ml/m2, p=0,000003). There was also a higher level of cardiovascular SCORE risk (5,0 (2,0; 6,0) vs 2,0 (1,0; 3,0), p=0,004); patients more often had associated clinical conditions (36,6% vs 12,7%, χ2=7,57, p=0,006) and left ventricular diastolic dysfunction (39,02% vs 78,18%, χ2=15,21, p=0,0001). Pathological BP increase during stress echocardiography was associated with worse exercise tolerance (7,4 (5,6; 10,0) METs vs 10,2 (8,4; 11,95) METs, p=0,000041) and more frequent transient regional contractility impairment (46,34% vs 1,8%, p<0,00001), mainly of the lateral and inferior left ventricular walls.Conclusion. Despite the absence of coronary artery stenosis, patients with hypertensive response to exercise are significantly more likely to have markers of high cardiovascular risk and require more careful monitoring of risk factors. Also, the hypertensive response to exercise is associated with more frequent regional contractility impairment even without coronary artery stenosis.

Download Full-text