Effect of increased wall thickness on indices of left ventricular pump function in children

Elevated brain natriuretic peptide and reduced exercise capacity in adult patients operated on for tetralogy of fallot is due to biventricular dysfunction as determined by the myocardial performance index

Although tetralogy of Fallot (TOF) can be repaired surgically, residual lesions that cause abnormal ventricular load can eventually lead to heart failure. Subclinical biventricular dysfunction in these patients may be detected only by using suitably sensitive indexes. The Tei index determined by the pulsed Doppler method enables the measurement of left ventricular (LV) and right ventricular (RV) function. This study was designed to evaluate the biventricular Tei indexes in adults with operated congenital heart disease and to correlate these indexes with cardiopulmonary capacity and neurohormonal activation. Fifty-nine patients with surgically corrected TOF and 52 patients with operated left-to-right-shunt defects were included in the study. Patients with TOF showed significantly greater LV and RV Tei indexes than those with left-to-right-shunt defects (LV Tei index 0.50 +/- 0.09 vs 0.34 +/- 0.05, RV Tei index 0.37 +/- 0.1 vs 0.25 +/- 0.06; p <0.0001). Peak oxygen uptake was significantly reduced in the patients with TOF (25 +/- 6 vs 32 +/- 6 ml x kg(-1) x min(-1), p <0.0001) and was correlated inversely with the LV Tei index (r = -0.61, p <0.0001). N-terminal-pro-brain natriuretic peptide was significantly increased in patients with TOF (150 +/- 141 vs 57 +/- 39 pg/ml, p <0.0001). In conclusion, in asymptomatic or minimally symptomatic patients with TOF, biventricular dysfunction is detected by the Tei index. Further indexes for heart failure in these patients are increased circulating plasma N-terminal-pro-brain natriuretic peptide and impaired peak oxygen uptake. The combined determinations of these 3 variables enable the identification of congenital heart disease with impaired cardiac function before they become clinically symptomatic.

Anaesthetic management of infants with glycogen storage disease type II: a physiological approach

Pompe or Glycogen Storage Disease type II (GSD-II) is a genetic disorder affecting both cardiac and skeletal muscle. Historically, patients with the infantile form usually die within the first year of life due to cardiac and respiratory failure. Recently a promising enzyme replacement therapy has resulted in improved clinical outcomes and a resurgence of elective anaesthesia for these patients. Understanding the unique cardiac physiology in patients with GSD-II is essential to providing safe general anaesthesia.

Left ventricular midwall mechanics in healthy children and adolescents

The assessment of left ventricular function in pediatric age generally has been made by measuring the extent and velocity of fiber shortening at the endocardium and relating these parameters to systolic wall stress. It has been suggested from animal and human studies that this "endocardial method" can result in an overestimation of myocardial function when healthy hearts and those with hypertrophy are compared. Thus an assessment of left ventricular pump function and contractility that takes into account the epicardial migration of the midwall circumferential fibers during systole (midwall analysis) is warranted. Although the normal range for midwall indexes of left ventricular mechanics has been established in adult subjects, up to now it has not been studied in pediatric subjects. To establish normal values for left ventricular midwall mechanics, 70 healthy children ranging in age from 3 days to 18 years were evaluated with 2-dimensional and M-mode echocardiography. Midwall fractional shortening (FSmw), rate-corrected mean velocity of circumferential fiber shortening (VCFcmw), and the relation between these indexes and left ventricular end-systolic wall stress (ESS) were calculated separately for the children younger than 2 (group 1, 20 subjects) and older than 2 (group 2, 50 subjects) years of age. Group 1 had significantly higher FSmw and VCFcmw compared with group 2. An inverse linear relation between FSmw and ESS and between VCFcmw and ESS was found in both age groups. The y-intercept was higher in group 1, and the slope of the mean regression line was steeper than in group 2 for both the relationships, suggesting an age-dependent midwall left ventricular pump function and contractility. These normative data can be used to assess the left ventricular midwall mechanics in pediatric patients with pressure or volume overload.