Significance of ST-segment morphology noted on electrocardiography during the recovery phase after exercise in patients with ischemic heart disease as analyzed with simultaneous dual-isotope single photon emission tomography

Impact of acute dynamic exercise and arterial shear rate modification on radial artery low-flow mediated constriction in young men

Purpose

Leg cycling exercise acutely augments radial artery low-flow mediated constriction (L-FMC). Herein, we sought to determine whether this is associated with exercise-induced changes in arterial shear rate (SR).

Methods

Ten healthy and recreationally active young men (23 ± 2 years) participated in 30 min of incremental leg cycling exercise (50, 100, 150 Watts). Trials were repeated with (Exercise + WC) and without (Exercise) the use of a wrist cuff (75 mmHg) placed distal to the radial artery to increase local retrograde SR while reducing mean and anterograde SR. Radial artery characteristics were measured throughout the trial, and L-FMC and flow mediated dilatation (FMD) were assessed before and acutely (~ 10 min) after leg cycling.

Results

Exercise increased radial artery mean and anterograde SR, along with radial artery diameter, velocity, blood flow and conductance (P < 0.05). Exercise + WC attenuated the exercise-induced increase in mean and anterograde SR (P > 0.05) but also increased retrograde SR (P < 0.05). In addition, increases in radial artery blood flow and diameter were reduced during Exercise + WC (Exercise + WC vs. Exercise, P < 0.05). After Exercise, L-FMC was augmented (− 4.4 ± 1.4 vs. − 13.1 ± 1.6%, P < 0.05), compared to no change in L-FMC after Exercise + WC (− 5.2 ± 2.0 vs. − 3.0 ± 1.6%, P > 0.05). In contrast, no change in FMD was observed in either Exercise or Exercise + WC trials (P > 0.05).

Conclusions

These findings indicate that increases in L-FMC following exercise are abolished by the prevention of increases radial artery diameter, mean and anterograde SR, and by elevation of retrograde SR, during exercise in young men.

Impact of acute dynamic exercise on radial artery low-flow mediated constriction in humans

Purpose

A “low-flow mediated constriction” (L-FMC) is evoked in the radial artery by the inflation of an ipsilateral wrist cuff to a supra-systolic pressure. We sought to test the hypothesis that the radial artery L-FMC response is augmented immediately following acute dynamic leg exercise in young healthy individuals.

Methods

Ten healthy and recreationally active men (23 ± 4 years) undertook a 30-min trial of incremental dynamic leg cycling exercise (10 min at 50, 100 and 150 W) and a 30-min time control trial (seated rest). Trials were randomly assigned and performed on separate days. Radial artery characteristics (diameter, blood flow and shear rate) were assessed throughout each trial, with L-FMC and flow-mediated vasodilatation (FMD) assessments conducted prior to and immediately following (10 min) trials.

Results

Dynamic leg cycling exercise increased radial artery blood flow, along with mean, retrograde and anterograde shear rate (P < 0.05). Blood flow profiles were unchanged during the time control trial (P > 0.05). Following exercise L-FMC was increased (mean [SD]; − 5.6 [3.3] vs. − 10.1 [3.8] %, P < 0.05), while it was not different in the time control condition (− 8.1 [3.2] vs. − 6.7 [3.4] %, P > 0.05). FMD was not different following either the exercise or time control trials (P > 0.05), but the composite end-point of L-FMC + FMD was enhanced post-exercise (P < 0.05).

Conclusions

Dynamic exercise with a large muscle mass acutely augments the vasoconstrictor response of the radial artery in response to a reduction in blood flow (L-FMC) in young healthy individuals. The time course of this post-exercise response and the underlying vasoregulatory mechanisms require elucidation.

Evaluation of ST‐segment changes during and after maximal exercise tests in one‐, two‐ and three‐vessel coronary artery disease

OBJECTIVE

To relate ECG and heart rate (HR) variables during and after exercise testing with the presence of one-, two- or three-vessel disease defined by angiography.

DESIGN

Seventy-three male patients with stable angina pectoris and angiographically verified coronary artery disease underwent a maximal exercise test. From 12-lead ECG recordings and computer averaging ST-amplitude and HR data were measured in consecutive 10-s intervals.

RESULTS

In univariate analysis, patients with three-vessel disease had lower maximal exercise capacity, a shorter time to >1 mm ST-depression, more often a clockwise ST/HR recovery loop, more frequently a post-exercise downward ST-segment slope, and a greater ST-deficit at 3.5 min after exercise than patients with one-vessel disease. In multivariate analysis, time to >1 mm ST-depression discriminated between patients with three- and one-vessel disease. In patients with an intermediate time to >1 mm ST-depression a clockwise ST/HR recovery loop and/or a downsloping ST-segment in the post-exercise period were significantly more prevalent in severe vessel disease.

CONCLUSION

Patients with three-vessel disease had a significantly shorter time to >1 mm ST-depression during exercise and more often an abnormal post-exercise ST/HR reaction than those with one-vessel disease.

Severity of exercise-induced ischemia with chest pain and recovery from ischemia after the disappearance of chest pain

The severity of exercise-induced painful ischemia and its recovery after the disappearance of pain are unknown. The aim of this study was to investigate the difference in severity of ischemia at both exercise and postexercise between painful ischemia and painless ischemia. After injections of technetium-99m tetrofosmin at peak ergometer exercise and thallium-201 at 3 minutes postexercise, dual-isotope single photon emission tomography was performed in 78 patients with angiographically proven ischemic heart disease. The extent of ischemic areas (the number of areas), the depth of ischemia in the ischemic area (the severity score of ischemia) and the extension of ischemia toward long axis of the left ventricle (the number of left ventricular levels with ischemic areas in apical, middle, and basal levels) at both exercise and postexercise were compared on the basis of the presence of pain and a history of diabetes mellitus (DM). The symptoms improved within 3 minutes postexercise in all painful ischemia patients. Of 59 patients with reversible ischemia, except for 4 painful ischemia patients with DM, the extent and depth of ischemia at postexercise were more severe in 14 painful ischemia patients without DM and 13 painless ischemia patients with DM than 28 painless ischemia patients without DM (extent; 2.9 +/- 1.7 areas, 3.5 +/- 2.8 areas versus 1.4 +/- 1.8 areas, P = 0.005, depth; 3.8 +/- 3.1 scores, 5.8 +/- 5.4 scores versus 1.9 +/- 3.0 scores, P = 0.0084, respectively) despite a comparable severity of ischemia at peak exercise (extent; 5.4 +/- 2.6 areas, 6.0 +/- 2.4 areas versus 4.3 +/- 3.3 areas, depth; 9.3 +/- 5.7 scores, 10.7 +/- 7.3 scores and 7.5 +/- 8.1 scores, all NS). The extension of ischemia toward long-axis of the left ventricle at both peak exercise and postexercise was more severe in the former 2 groups than the latter group (peak exercise; 2.4 +/- 0.6 levels, 2.5 +/- 0.7 levels versus 1.9 +/- 0.8 levels, P = 0.0263, postexercise: 1.8 +/- 0.7 levels, 1.5 +/- 0.9 levels versus 0.8 +/- 0.8 levels, P = 0.0014, respectively). The presence of chest pain is related to the extension of ischemia toward long-axis of the left ventricle, and the disappearance of pain was not related to the recovery of ischemia.

Significance of extension of exercise-induced ischemia toward apex of left ventricle

BACKGROUND

The aim of this study was to evaluate the significance of extension of exercise-induced ischemia toward apex of left ventricle.

METHODS

After injections of technetium-99m tetrofosmin at peak ergometer exercise and thallium-201 at 3 min post-exercise, dual-isotope single photon emission computed tomography (SPECT) images were obtained simultaneously with cross-talk compensation using triple-energy window in 70 patients (65.8+/-9.5 years) with angiographically proven ischemic heart disease. The left ventricle was divided into a total of 18 areas in 3 levels of apical, middle, basal, and the extent and localization of ischemia to long axis of left ventricle were measured at peak exercise and 3 min into the recovery.

RESULTS

Of 57 patients with exercise-induced reversible ischemia, in 25 patients with the ischemia in 2 levels to long axis of left ventricle, the ischemia extended mainly to the middle and basal levels (p<0.0001) and was localized during recovery mainly in the basal level (p<0.0005). In 21 patients with the ischemia in all 3 levels, the ischemia was localized during recovery mainly to the middle and basal levels (p<0.05). The persistence of ischemia in apex at post-exercise reflected the delay of recovery from ischemia on the whole of left ventricle and was related to the enlargement of resting end-diastolic volume of left ventricle as compared to the quick recovery of ischemia in apex (p<0.0005 and p<0.05, respectively).

CONCLUSIONS

Although the ischemia recovers earliest in the peripheral apical level within exercise-induced ischemic territory, the delay of recovery from the ischemia in the apical level may be related to the development of heart failure, independent of intensity of occurred ischemia during exercise.