S. Del Colle

Relationship between QT interval and cardiovascular risk factors in healthy young subjects

A prolongation of QT interval increases the risk for coronary heart disease, ventricular arrhythmias, and sudden death in diabetic patients, after myocardial infarction, and in the elderly. An association between QT prolongation and cardiovascular risk factors has been demonstrated in middle-aged and elderly subjects. Aims of this study were to evaluate the prevalence of a prolonged corrected QT interval (QTc) in a healthy young population (n=170, age 22–25 years, 84 males) and to investigate the association of QTc and QT dispersion (QTd) with cardiovascular risk factors (body mass index, blood pressure, fasting blood glucose and cholesterol, smoking habits, and hypertensive familiarity). A prolonged QTc was observed in 10% of female and 5% of male subjects; in multiple regression analysis, QTc showed a significant positive relationship with blood glucose in females (P=0.04) and systolic blood pressure in male subjects (P=0.03), while QTd was not significantly related with any of the factors. In conclusion, the association between QTc length, glucose levels, and blood pressure is present also in young healthy subjects. QT measurement may represent a useful marker in the screening of young subjects for cardiovascular prevention.

Baroreflex sensitivity is impaired in essential hypertensives with central obesity.

Recently, much interest has focussed on the potential interaction between sympathetic nervous system and global cardiovascular risk. We investigated how baroreflex sensitivity (BRS), an index of autonomic function, interacts with central obesity (CO) in an essential hypertensive (EH) population. We selected 170 EHs and 43 normotensives (NT), (median age 47.3±11.3 and 49.1±13 years, respectively). Anthropometric parameters were measured for each and BRS was evaluated by a non-invasive method using Portapres TNO. The BRS evaluation was made using the sequences method. Systolic blood pressure (SBP) and heart rate were significantly higher in EH (P<0.001 and P=0.007, respectively). BRS was significantly greater in NT (P=0.02), and was associated inversely with waist circumference (WC) (P=0.005), but not with SBP or with other metabolic risk factors. Body mass index, total and high-density lipoprotein cholesterol, age and WC were not significantly different between the two groups. These results were confirmed by age pounded analysis. Finally, a separate analysis of the hypertensive group with CO (n=84) demonstrated a significantly lower BRS compared with the other hypertensive patients (n=86) (P<0.001). BRS is associated with WC but not with arterial pressure values and metabolic risk factors. Hypertensive subjects with CO show an impairment of BRS. Owing to its association with abdominal fat distribution and subsequently insulin resistance, BRS could represent a further and reliable index for evaluation of global cardiovascular risk in hypertensive patients.

Pulse rate in childhood: reference limits

BACKGROUND AND AIMnSystematic quantitative resting pulse rate measurements may represent an additional parameter for the study of cardiovascular risk factors in youth as well as in adulthood. The aim of this study was to evaluate resting pulse rate and its distribution curve in order to define reference limits in a sample of adolescents from Turin, Italy.nnnMETHODS AND RESULTSnThe study population consisted of 2230 children aged 12-18 years, who were randomly enrolled from Turin Junior High Schools. All of the participants underwent pulse rate, blood pressure and height measurements. The 5th and 95th percentiles of the pulse rate in boys and girls are reported by age and height. The pulse rate was higher in the girls, but progressively decreased with age and somatic growth in both genders.nnnCONCLUSIONSnThe present study provides reference blood pressure values by age, gender and height in a sample of male and female adolescents.

Retraction: Left atrial function and arterial hypertension

Left atrial enlargement is frequently observed in many cardiac diseases. One of the main determinants of left atrial size is ventricular diastolic function. It has recently been suggested that left atrial volume might be the morphophysiologic expression of long-term modifications induced by diastolic function. Furthermore, left ventricular remodelling, such as it happens in hypertensive patients, is another important determinant of atrial volume. All the volumetric modifications of the left atrium, during cardiac cycle, are involved in hypertensive damage. Therefore, left atrial function impairment represents the result of morphological and haemodynamic alterations observed in hypertension. Actually, many techniques, invasive and non-invasive, are available with the purpose to investigate the real atrial dimensions and provide a suitable assessment of atrial function. Recently, it has been demonstrated that the degree of left atrial enlargement is associated with adverse prognosis in different clinical setting. The predictive value of left atrial volume seems to be independent of left ventricular systolic and diastolic function, but the use of left atrial volume for risk stratification is yet an evolving science: more data are required with respect to the natural history of left atrial remodelling in disease, the degree of left atrial modifiability with therapy and whether regression of left atrial size translates into improved cardiovascular outcome.Journal of Human Hypertension advance online publication, 14 August 2008; doi:10.1038/jhh.2008.96.

Left atrial function and arterial hypertension

Left atrial enlargement is frequently observed in many cardiac diseases. One of the main determinants of left atrial size is ventricular diastolic function. It has recently been suggested that left atrial volume might be the morphophysiologic expression of long-term modifications induced by diastolic function. Furthermore, left ventricular remodelling, such as it happens in hypertensive patients, is another important determinant of atrial volume. All the volumetric modifications of the left atrium, during cardiac cycle, are involved in hypertensive damage. Therefore, left atrial function impairment represents the result of morphological and haemodynamic alterations observed in hypertension. Actually, many techniques, invasive and non-invasive, are available with the purpose to investigate the real atrial dimensions and provide a suitable assessment of atrial function. Recently, it has been demonstrated that the degree of left atrial enlargement is associated with adverse prognosis in different clinical setting. The predictive value of left atrial volume seems to be independent of left ventricular systolic and diastolic function, but the use of left atrial volume for risk stratification is yet an evolving science: more data are required with respect to the natural history of left atrial remodelling in disease, the degree of left atrial modifiability with therapy and whether regression of left atrial size translates into improved cardiovascular outcome.Journal of Human Hypertension advance online publication, 14 August 2008; doi:10.1038/jhh.2008.96.