The effect of rapid blood pressure control on P-wave dispersion in hypertensive urgency

Reversible Increases in Qt Dispersion and P Wave Dispersion during Carbon Monoxide Intoxication

Objectives

Carbon monoxide (CO) is a potent myocardial toxin. We investigated the association between acute CO intoxication and electrocardiographic QT interval (QTmax/QTmin), corrected QT interval (cQTmax/cQTmin), QT dispersion (QTd) and corrected QT dispersion (cQTd), P wave duration (Pmax/Pmin) and P wave dispersion (Pd), which were known as predictors of ventricular arrhythmias, atrial fibrillation and sudden death.

Methods

Electrocardiography with 12-leads and blood gas were taken from 65 patients with CO intoxication as well as 65 control patients with similar age and gender distribution at the admission time to the emergency department and at the 4th hour post-therapy. The carboxyhaemoglobin (COHb) levels and the relationships with electrocardiographic parameters were studied.

Results

The mean COHb levels were 21.43±6.85% and 1.37±0.98% in intoxicated patients and in the control group respectively. QTmax, QTd, cQTmax, cQTd, Pmax, and Pd were found significantly higher in intoxicated patients when compared to the control group (373.98±40.35 vs. 355.98±32.88, p=0.006; 49.29±22.66 vs. 20.43±11.16, p<0.001; 455.38±30.72 vs. 419.57±22.27, p<0.001; 60.88±25.99 vs. 25.75±13.13, p<0.001; 107.91±13.28 vs. 96.65±12.65, p<0.001, 46.85±13.49 vs. 35.22±10.07, p<0.001 respectively). In Pearson correlation analysis, there were significant correlations between COHb level and QTmax, QTd, cQTmax, cQTd, Pmax and Pd (r=0.211, p=0.016; r=0.610, p<0.001; r=0.599, p<0.001; r=0.628, p<0.001; r=0.458, p<0.001; r=0.414, p<0.001 respectively).

Conclusion

A correlation between reversible increases in QTd, cQTmax, cQTd, Pmax and Pd in the electrocardiogram and COHb can be observed in acute CO intoxication patients.

Effect of lifetime endurance training on left atrial mechanical function and on the risk of atrial fibrillation

BACKGROUND

Left atrium (LA) dilation and P-wave duration are linked to the amount of endurance training and are risk factors for atrial fibrillation (AF). The aim of this study was to evaluate the impact of LA anatomical and electrical remodeling on its conduit and pump function measured by two-dimensional speckle tracking echocardiography (STE).

METHOD

Amateur male runners >30 years were recruited. Study participants (n=95) were stratified in 3 groups according to lifetime training hours: low (<1500 h, n=33), intermediate (1500 to 4500 h, n=32) and high training group (>4500 h, n=30).

RESULTS

No differences were found, between the groups, in terms of age, blood pressure, and diastolic function. LA maximal volume (30±5, 33±5 vs. 37±6 ml/m(2), p<0.001), and conduit volume index (9±3, 11±3 vs. 12±3 ml/m(2), p<0.001) increased significantly from the low to the high training group, unlike the STE parameters: pump strain -15.0±2.8, -14.7±2.7 vs. -14.9±2.6%, p=0.927; conduit strain 23.3±3.9, 22.1±5.3 vs. 23.7±5.7%, p=0.455. Independent predictors of LA strain conduit function were age, maximal early diastolic velocity of the mitral annulus, heart rate and peak early diastolic filling velocity. The signal-averaged P-wave (135±11, 139±10 vs. 148±14 ms, p<0.001) increased from the low to the high training group. Four episodes of non-sustained AF were recorded in one runner of the high training group.

CONCLUSION

The LA anatomical and electrical remodeling does not have a negative impact on atrial mechanical function. Hence, a possible link between these risk factors for AF and its actual, rare occurrence in this athlete population, could not be uncovered in the present study.