Negative U wave during percutaneous transluminal coronary angioplasty

The appearance of negative U waves in the precordial leads during balloon occlusion of the long posterior descending artery

This report presents a patient in which balloon occlusion of the posterior descending artery wrapping the apex produced negative U waves in leads V(4-5). This case report demonstrates, for the first time, that negative U waves in the precordial leads can appear by occlusion of the long posterior descending artery.

Electrocardiographic T- and U-wave discordance

BACKGROUND

Abundant information has been reported regarding the U wave, which almost entirely has been focused on U waves in isolation. There has been little investigation of discordant T and U waves.

METHODS

Of 18,750 consecutively recorded electrocardiograms, 143 patients were categorized resulting in three groups. Group A: 53 patients with negative T waves and positive U waves (Type I Discordance); Group B: 26 patients with positive T waves and negative U waves (Type II Discordance); and Group C: 63 patients with negative T and negative U waves. Each patient's chart was reviewed for relevant clinical, laboratory, and medical history.

RESULTS

Coronary disease was slightly more common in Group A (64%) than in Group B (46%) (P = 0.174; ns). Coronary disease in Group C was extremely common (88%; P <0.001). Hypertension in the two discordant groups was similar: Group A (60%) versus Group B (58%) (P = ns), Group C was significantly higher (88%) (P <0.001). Left ventricular hypertrophy was 49% in Group A and 58% in Group B (P = ns), but Group C was significantly higher at 70% (P = 0.038).

CONCLUSIONS

This appears to be the first investigation of the associations of discordant T and U waves. We found that the significance of any U wave is not independent of their respective T wave. In addition, we propose that the U wave not be analyzed in isolation, but rather with respect to its T wave.

Occurrence of transient U-wave inversion during vasospastic anginal attack is not related to the direction of concurrent ST-segment shift

STUDY OBJECTIVES

We sought to assess the incidence of transient U-wave inversion during vasospasm of the left anterior descending coronary artery (LAD) with ST-segment depression as opposed to that with ST-segment elevation.

DESIGN

Retrospective study.

SETTING

Cardiology division of acute-care hospitals.

PATIENTS

We studied 49 patients with vasospastic angina whose vasospasm was induced in the LAD, not in the left circumflex coronary artery, by intracoronary injection of acetylcholine.

MEASUREMENTS AND RESULTS

The ECG traces obtained during acetylcholine-induced vasospasm of the LAD were examined. Based on the direction of ST-segment shift, the patients were categorized into two groups: the ST-segment elevation group (n = 27) and the depression group (n = 22). There were no differences in age, gender, or cardiovascular risk factors between the two groups. The distribution of the spastic site in the LAD was also similar. A total reduction in luminal diameter during a provoked attack was more often observed in the ST-segment elevation group than in the ST-segment depression group (37% vs 9%, p = 0.02). Collateral circulation to the LAD was found in only one patient in each group. There were no differences between the two groups in heart rate, systolic BP, and double product of heart rate and systolic BP during the attack. The incidence of acetylcholine-induced anginal attack with U-wave inversion in the ST-segment depression group was nearly as high as that in the ST-segment elevation group (77% vs 78%, p > 0.99).

CONCLUSIONS

The development of transient U-wave inversion during vasospasm of the LAD induced by intracoronary injection of acetylcholine does not depend on the magnitude of myocardial ischemia as judged by the direction of ST-segment shift.

Transient U wave inversion during treadmill exercise testing in patients with left anterior descending coronary artery disease

The transient U wave inversion during exercise is specific for detecting left anterior descending coronary artery (LAD) disease. In a homogeneous patient group restricted to LAD disease, however, the significance of the electrocardiographic finding has not yet been clarified. Thus, clinical characteristics in patients with angiographically documented one-vessel disease of the LAD and exercise-induced U wave inversion were delineated. Symptom-limited treadmill exercise testing was performed in 60 patients (43 men, 17 women; mean age 64 +/- 8 years) with angina pectoris whose culprit lesion was located only in the LAD. U wave polarity and amplitude were determined before, during, and after exercise with the P-Q segment as the isoelectric line. Exercise-induced transient U wave inversion was defined as positive when there was a discrete negative deflection > or = 0.05 mV within the T-P segment. Of all patients, 16 (27%) had exercise-induced U wave inversion. There were no differences in age, male gender, antianginal medication use, and coronary angiographic data between the two patients groups: patients with and without U wave inversion. Heart rate and double product of heart rate and systemic systolic blood pressure at peak exercise were also similar. Prevalence of abnormal exercise-induced S-T segment shift was 94% (15 of 16 patients) and 61% (27 of 44 patients) of patients with and without U wave inversion, respectively. The difference was statistically significant (p = 0.02). Among patients with exercise-induced S-T segment shift, the proportion of patients with S-T segment elevation to all the patients was larger in patients with U wave inversion than in patients without U wave inversion [3 (20%) of 15 patients vs 0 (0%) of 27 patients, p = 0.03)]. In conclusion, the exercise-induced U wave inversion in patients with one-vessel disease of the LAD indicates the severe degree of myocardial ischemia induced in the territory perfused by the LAD. However, the electrocardiographic finding does not appear to have independent significance since it closely correlates with the presence of S-T segment shift.

How epicardial U-wave changes are reflected in body surface precordial electrocardiograms in anterior or inferoposterior myocardial ischaemia during coronary angioplasty

OBJECTIVES

To examine the epicardial U-wave changes recorded in intracoronary electrocardiograms (ECGs) during anterior or inferoposterior myocardial ischaemia and the corresponding changes in precordial ECGs recorded from the body surface in humans.

METHODS

40 patients undergoing coronary angioplasty of the left anterior descending (LAD) coronary artery (22 patients) or left circumflex (LC) artery (18 patients). Intracoronary and surface precordial ECGs were simultaneously recorded under baseline conditions and during angioplasty.

RESULTS

Four different patterns of U-wave change were identified on the intracoronary ECG: change to positivity, no change, change to negativity, and biphasic change. The incidence of each pattern was similar in the two groups (LAD v LC groups, 23% v 39%; 23% v 17%; 41% v 44%; 13% v 0%, respectively). The intracoronary ECG was more sensitive than the surface ECG for detecting U-wave changes (intracoronary v surface ECG: LAD group, 77% v 55%; LC group, 83% v 28%). A study of the correlation between intracoronary and surface precordial ECGs showed that in patients who had U-wave changes in their intracoronary ECG (17 LAD and 15 LC patients) 65% of the LAD group but only 6% of the LC group had primary U-wave changes in the surface precordial ECG, and that 27% of the LC patients had reciprocal U-wave changes in the right to central precordial ECG.

CONCLUSIONS

These results provide fundamental information for an understanding of the correlation between U-wave changes in the epicardial and surface pre-cordial ECGs during myocardial ischaemia in humans. As well as the primary U-wave changes seen in many of those with anterior myocardial ischaemia, some of those with posterior myocardial ischaemia had reciprocal U-wave changes in their surface precordial ECGs.