Comparison of exercise and catheterization results following total surgical correction of tetralogy of Fallot.

Although surgery may correct the hemodynamic abnormalities of tetralogy of Fallot (TOF), the long-term effects on exercise tolerance are uncertain. Twenty-eight patients, aged 7 to 30 years, had cardiac catheterization and maximal graded exercise testing to evaluate the adequacy of the ehmodynamic repair and its relation to exercise performance. Patients were tested 2 to 9 years after operation, and 13 previously had had palliative shunt procedures. At catheterization, 23 of the 28 patients had good surgical results. Despite the satisfactory hemodynamics, maximal working capcity (MWC), maximum heart rate, and exercise blood pressure were diminished when compared to normal values. In 10 patients who had exercise studies at catheterization, right ventricular systolic pressure (RVSP) and residual gradients were magnified by exercise. Abnormalities were independent of age at time of correction, time elapsed since surgery, use of patch in the outflow tract, or any antecedent procedures.

A polymer-Triton X-100 conjugate capable of PH-dependent red blood cell lysis: a model system illustrating the possibility of drug delivery within acidic intracellular compartments.

Poly(amidoamines) are soluble polymers containing tertiary amino and amido groups regularly arranged along the macromolecular chain, and their net average charge alters considerably as pH changes from neutral to acidic leading to a change in conformation. This property provides the possibility to design polymer-drug conjugates that are, following intravenous administration, relatively compacted and thus protect a drug payload in the circulation, but following pinocytic internalisation into acidic intracellular compartments unfold permitting pH-triggered intracellular drug delivery. To study the feasibility of this approach, a covalent conjugate of a poly(amidoamine) (MBI) was prepared to contain the membrane lytic non-ionic detergent Triton X-100 (as a model), and its ability to lyse red blood cells in vitro was used as an indicator of conjugate conformation at at different pHs. Although Triton X-100 was highly lytic at pH 5.5, 7.4 and 8.0, and the parent polymer MBI was not lytic under any conditions, the conjugate only showed concentration-dependent red blood cell lysis at pH 5.5. Moreover, incubation of human leukaemic cells (CCRF) with these substrates showed conjugate to be more toxic than MBI (IC50 values of 100 micrograms/ml and 650 micrograms/ml respectively) and less toxic than Triton X-100 (IC50 of 1 microgram/ml).

The cardiovascular abnormalities associated with duplicated segments of chromosome 7.

Congenital heart disease is an integral part of many genetic syndromes such as the major trisomies 13, 18, and 21. Little information, however, is available with reference to the incidence of cardiac anomalies in the trisomy 7 syndromes. Two patients with partial trisomy 7q, one of whom had congenital heart disease, are presented. A review of the literature reveals incomplete description of the cardiovascular abnormalities in the majority of case reports of patients with this syndrome, however, when described it appears that there are no specific defects associated with trisomy 7p and 7q, but only an increased frequency of occurrence. Further clinical and postmortem data regarding details of the congenital heart defects associated with trisomy 7 is required to confirm this preliminary observation.

Cardiovascular effects of cocaine in neonates exposed prenatally.

This blinded cross-sectional study was to determine whether chronic cocaine exposure in utero produces abnormalities in left ventricular function (shortening fraction), heart rate, rhythm, and conduction in term neonates. Three groups of neonates were evaluated by two-dimensional echo Doppler and 24 hour Holter monitor, with studies initiated in the first 24 hours of life. Group A (n = 32) neonates had a positive history of chronic maternal cocaine use in pregnancy (MCU+) and a positive neonatal urine cocaine test (NUC+). Group B (n = 23) neonates were MCU+ but NUC-. Group C (n = 32) neonates were MCU- and NUC-. Measured parameters were compared statistically by analysis of variance. p < 0.05 was regarded as significant. Echocardiography showed no significant difference between groups A, B, and C for left ventricular shortening fraction. Holter monitor likewise revealed no significant difference between groups in minimal, maximal, and average heart rate, or in the incidence of supraventricular and ventricular arrhythmias greater than 20 beats/h in the 24-hour period. None of the patients had atrioventricular or bundle branch block. It is possible that the developmental state of the newborn heart makes it less responsive to the adverse effects of cocaine.