Transradial coronary intervention without pre-screening for a dual palmar blood supply.

It is usual practice to determine the presence of collateral blood supply to the hand prior to radial artery cannulation. We propose that pre-screening for a dual palmar vascular supply is not necessary and the presence of a palpable radial pulse is sufficient to allow successful radial artery cannulation. We retrospectively analysed our interventional PTCA registry, including only patients who had a transradial procedure without being pre-screened with an Allen's test or plethysmography. We report our data including complications the day after the procedure and at 30 days, and provide an up to date discussion on the need to assess patients for a dual palmar blood supply prior to transradial intervention.

Cardiovascular complications induced by cannabis smoking: a case report and review of the literature.

Cannabis is generally considered a drug of low toxicity. Although attention has focused on its neuropsychiatric effects, little has been given to cardiovascular side effects. Here we report a case of atrial tachyarrhythmias following cannabis use, and review the literature on its cardiovascular effects and complications.

Circadian behavior of P-wave duration, P-wave area, and PR interval in healthy subjects.

BACKGROUND: The prolongation of P-wave duration has long been shown to indicate the presence of high risk for atrial fibrillation. The circadian variation of P-wave characteristics and their dynamic adaptation to heart rate changes was not tested before. METHODS: To evaluate the diurnal pattern of P-wave duration, P area, and PR interval and of their linearly fitted relation with RR interval, 50 healthy volunteers (25 men, mean age 34 +/- 10 years) underwent 24-hour ambulatory electrocardiographic (ECG) recording with digital 12-lead Holter recorders. The median P-wave duration, P area, and PR interval were calculated from the average 12-lead ECG constructed from each 10-second ECG recording. Single harmonic regression analysis was performed to reveal the presence of circadian variation in the aforementioned ECG parameters. RESULTS: The P area (P < 0.0001, R(2) = 0.78), the PR interval (P < 0.0001, R(2) = 0.92), the P area / RR slope (P < 0.0001, R(2) = 0.55), and the PR/RR slope (P < 0.0001, R(2) = 0.42) showed a highly significant circadian variation while the periodic nature of P-wave duration (P = 0.016, R(2) = 0.32) and of the P duration / RR slope (P = 0.011, R(2) = 0.18) was only indicated by harmonic regression analysis. CONCLUSIONS: P-wave duration, P area, and PR interval show a significant circadian variation in healthy subjects. The relations between P area/RR,PR/ RR, and P duration/RR also demonstrate a significant diurnal pattern.

Ischaemic heart disease presenting as arrhythmias.

Despite considerable progress in management over the recent years, coronary artery disease (CAD) remains the leading cause of death in the industrialised world. It is estimated that CAD is responsible for causing 152,000 deaths per year in the UK and one in eight deaths world-wide. Many of these deaths are attributed to the development of ventricular tachyarrhythmias during periods of myocardial ischaemia or infarction. Myocardial ischaemia is characterised by ionic and biochemical alterations, creating an unstable electrical substrate capable of initiating and sustaining arrhythmias, and infarction creates areas of electrical inactivity and blocks conduction, which also promotes arrhythmogenesis. The purpose of this chapter is to review some of the metabolic changes associated with cardiac ischaemia, their relevance to electrophysiological instability, and the clinical manifestation and management of some of the more common arrhythmias that follow cardiac ischaemia. Particular attention is given to the peri-infarction period (arbitrarily accepted as within 48 h of the index myocardial infarction) as arrhythmias are most likely to be seen around this time, and are considered to be non-indicative of long-term prognosis. In contrast, arrhythmias developing in the post-infarction period (after 48 h) have been demonstrated to be associated with an adverse outcome. Regardless of the anti-arrhythmic therapy used in treating peri- and post-infarction arrhythmias, it is presumed that patients who had a myocardial infarction or who have left ventricular dysfunction will also receive other appropriate therapies, such as aspirin, ss-blockers, cholesterol lowering agents and angiotensin converting enzymes inhibitors.

New descriptors of homogeneity of the propagation of ventricular repolarization.

Available descriptors of irregularities of ventricular repolarization are of limited clinical value. We studied the effect of autonomic variations on several new descriptors of the three-dimensional T loop. Twelve-lead digital ECGs were recorded continuously in 40 healthy subjects at baseline in the supine position, during postural changes (supine-->sitting-->standing-->supine-->standing), and during Valsalva maneuver performed three times in the supine and three times in the standing positions. A minimum dimensional space was constructed from the 12-lead ECG, using singular value decomposition, on the basis of median ECG beats constructed from 10-second consecutive ECG recordings. Temporal variations (TLA and PL, which measure the T loop area, and LD, the interlead relationship during repolarization) and wavefront direction descriptors (TCRT, the deviation between the QRS and T vectors) were calculated and expressed as normalized values. Values of TLA, PL, and TCRT were significantly lower in the sitting than in the supine position (-38,139 +/- 9099 vs 47,133 +/- 7511, -0.017 +/- 0.005 vs 0.033 +/- 0.005 and -0.032 +/- 0.019 vs 0.071 +/- 0.015, respectively, P < 0.001 for all) and decreased further in the standing position (-88,288 +/- 14,468, -0.067 +/- 0.013, -0.198 +/- 0.025, respectively, P < 0.001 for all). LD increased from supine to sitting (98.7 +/- 29.4 vs -87.5 +/- 15.2, P < 0.001) and increased further, though nonsignificantly in the standing position (118.3 +/- 35.2). TLA, PL, and TCRT decreased from baseline during Valsalva in the supine (-34,118 +/- 11,424 vs 62,234 +/- 12,215, -0.038 +/- 0.014 vs 0.065 +/- 0.010, -0.08 +/- 0.03 vs 0.10 +/- 0.02, respectively, P < 0.001 for all) and standing positions (-108,263 +/- 21,051 vs -68,909 +/- 10,271, -0.109 +/- 0.014 vs -0.048 +/- 0.009, -0.30 +/- 0.035 vs -015 +/- 0.016, respectively, P < 0.05 for all). LD was significantly increased by Valsalva in the supine position (13 +/- 46 vs -153 +/- 30, P < 0.001) and nonsignificantly in the standing position (99 +/- 50 vs 86 +/- 30, P = NS). There were significant correlations among TLA, PL, and LD, and no significant correlation between TCRT and any of the temporal variation descriptors. These new temporal and wavefront direction descriptors are sensitive and rapid detectors of autonomic effects on ventricular repolarization.

Reflex autonomic modulation of automatically measured repolarization parameters.

Automatic recognition of repolarization abnormalities from the standard electrocardiogram (ECG) is of considerable clinical importance. This study examined the autonomic variations in automatically measured repolarization parameters, including maximum QT interval (QTmax), global QT dispersion (QTd), T area dispersion (T area D) and principal component analysis ratio 2 (PCA-2). Twelve-lead ECGs were recorded continuously in 40 healthy subjects during supine, sitting and standing positions, and during the Valsalva maneuver. With the exception of PCA-2, the other repolarization parameters correlated either moderately or strongly during the steady-state supine position. QTmax, PCA-2, and T area D decreased significantly between supine and sitting position (P < 0.001, P < 0.001 and P < 0.01, respectively). QTmax, QTD, and T area D decreased significantly between sitting and standing (P < 0.001, P < 0.05 and P < 0.01, respectively). All parameters significantly decreased between supine and standing position: QTmax (P < 0.001), QTD (P < 0.05), PCA-2 (P < 0.05) and T area D (P < 0.001). During Valsalva, only PCA-2 increased significantly (P < 0.001) between supine and standing position. There were no significant changes in QT dispersion and dispersion of T wave area during Valsalva, compared to baseline, in both supine and standing positions. Automatic conventional measures of repolarization heterogeneity have limited practical value in detecting the effects of autonomic changes on ventricular repolarization. Newer concepts evaluating spatial and temporal irregularity of ventricular repolarization are still needed to reliably detect the effects of autonomic activity on ventricular repolarization.