Pulsed tissue Doppler, when used in fetuses of diabetic mothers and compared with fetuses of nondiabetic mothers, shows evidence of impaired diastolic function, independently of the presence of myocardial hypertrophy.

No abstract

The incidence of insulin-dependent diabetes mellitus is about 0.8%, and gestational diabetes is 3-5%. Both are evidence of the metabolic disturbances of carbohydrates during pregnancy 1 . The incidence of congenital malformation is 3 to 4 times greater in children from diabetic mothers than in the general population 2 . Among those malformations, 50% are congenital cardiac diseases 3 . Maternal diabetes is a risk factor for congenital heart disease and an indication for fetal echocardiography [4][5][6][7][8][9][10][11][12] .Maternal hyperglycemia and the excess of glucose transferred to the fetus encourage fetal pancreatic islets to increase the production of insulin, leading to hyperinsulinism, which is responsible for fetal complications. Fetal myocardial hypertrophy is the most frequent abnormality found in newborns from diabetic mothers, and it may be found in up to 35% of these newborns 13 . The interventricular septum is particularly rich in insulin receptors 14 , which would justify increased hypertrophy in this segment, secondary to myocardial cell hyperplasia and hypertrophy due to the increased synthesis of fat and proteins.Fetal Doppler echocardiography has increased our knowledge about the cardiocirculatory changes in the prenatal period. Recent studies have shown significant changes in the cardiovascular flow of fetuses from diabetic mothers, especially in pregnancies with inadequate glycemic control 15 .With the introduction of echocardiography, several clinical studies have demonstrated normal patterns of pulmonary venous flow in children and adults through transesophageal and transthoracic echocardiography 16,17 . The use of the pulmonary vein pulsatility index as a parameter for diastolic function evaluation during fetal life has not yet been reported. Thus, we have tested the hypothesis that the pulmonary vein pulsatility index in fetuses from diabetic mothers is greater than that in fetuses from nondiabetic mothers, based on the idea that a less complacent left ventricle would increase presystolic flow impedance in the pulmonary vein, corresponding to the atrial contraction phases. Consequently, it would increase the pulsatility index in this vessel. Objective -To verify the hypothesis that the pulmonary vein pulsatility index is higher in fetuses of diabetic mothers than it is in normal fetuses of nondiabetic mothers. Methods -

Background-The usual positioning of the Doppler sample volume to assess fetal pulmonary vein flow is in the distal portion of the vein, where the vessel diameter is maximal. This study was performed to test the association of the pulmonary vein pulsatility index (PVPI) with the vessel diameter. Methods and Results-Twenty-three normal fetuses (mean gestational age, 28.6Ϯ5.3 weeks) were studied by Doppler echocardiography. Pulmonary right upper vein flow was assessed adjacent to the venoatrial junction ("distal" position) and in the middle of the vein ("proximal" position). The vessel diameter was measured by 2D echocardiography with power Doppler, and the PVPI was obtained by the ratio (maximal velocity [systolic or diastolic peak]Ϫminimal velocity [presystolic peak])/mean velocity. The statistical analysis used t test and exponential correlation studies. Mean distal diameter was 0.33Ϯ0.10 cm (0.11 to 0.57 cm), and mean proximal diameter was 0.16Ϯ0.08 cm (0.11 to 0.25 cm) (PϽ0.0001). Mean distal PVPI was 0.84Ϯ0.21 (0.59 to 1.38), and mean proximal PVPI was 2.09Ϯ0.59 (1.23 to 3.11) (PϽ0.0001). Exponential inverse correlation between pulmonary vein diameter and pulsatility index was highly significant (PϽ0.0001), with a determination coefficient of 0.439. Conclusions-In the normal fetus, the pulmonary venous flow pulsatility decreases from the lung to the heart, and this parameter is inversely correlated to the diameter of the pulmonary vein, which increases from its proximal to its distal portion. This study emphasizes the importance of the correct positioning of the Doppler sample volume, adjacent to the venoatrial junction, to assess pulmonary venous flow dynamics.

Age correlates with the tissue Doppler diastolic myocardial velocities and with the velocities of transmitral and pulmonary vein flows. In healthy individuals, the parameters of left ventricular diastolic function vary with the natural evolution of age.