Gerhard Gennser

Impaired Endothelial Function and Increased Carotid Stiffness in 9-Year-Old Children With Low Birthweight

BackgroundLow birthweight (LBW) has been associated with an increased incidence of adult cardiovascular disease. Endothelial dysfunction and loss of arterial elasticity are early markers of hypertension and atherosclerosis. We studied the prevalence of these markers in 44 healthy, prepubertal (age 9±1.3 years) children, 22 with LBW for age. Methods and ResultsEndothelial function in skin was tested with the local application of acetylcholine (inducing endothelium-dependent vasodilation) and nitroglycerin (endothelium-independent vasodilation), and local perfusion changes were measured with the laser Doppler method. The elastic properties of the abdominal aorta and common carotid artery were measured with an ultrasonic vessel-wall tracking system. Endothelium-dependent vasodilation was lower in children with LBW (88±33 perfusion units [PU]) than in normal-birthweight controls (133±34 PU, P <0.001). There was no difference in aortic or carotid elasticity between the 2 groups, but a negative correlation was found between birthweight and stiffness of the carotid artery wall (r =−0.45, P <0.01). Endothelium-independent vasodilation and blood pressure were similar in the 2 groups. ConclusionsSchoolchildren with a history of LBW show impaired endothelial function and a trend toward increased carotid stiffness. These findings may be early expressions of vascular compromise, contributing to susceptibility to disease in adult life.

Benefits of ultrasonic screening of a pregnant population.

Abstract. The present study describes the evolution over a 5‐year period of an ultrasonic routine screening programme of a pregnant population with participation of approximately 90 % of the pregnant women. One obvious result obtained in the screening programme is the pronounced improvement of early detection of twins, the incidence now approaching 95 % with the mean gestational age for the detection being 20 (median 19) weeks. Early detection in combination with clinical measures was associated with a decrease in the incidence of twins born preterm (before week 37) from 33 % to 10 %. The perinatal mortality rate of twins fell from 6 to 0.6 % after the introduction of this programme.

Increased large arterial stiffness and impaired acetylcholine induced skin vasodilatation in women with previous gestational diabetes mellitus

Objective Gestational diabetes is associated with increased risk of developing noninsulin‐dependent diabetes (NIDDM) later in life. By the time that a diagnosis of NIDDM is established, functional disturbances in the vascular system may be observed. This study was planned to assess macro‐ and microvascular function in nonpregnant women without signs of diabetes two to four years after a pregnancy complicated with gestational diabetes.

A Study of Smoking and Pregnancy with Special Reference to Fetal Growth

Abstract. A prospective study of the influence of smoking on pregnancy and its outcome was made of 5272 women in an urban community during 1974/75. Approximately 90 % of the pregnant women in the population took part in the programme. Ultrasonic measurements of the fetal biparietal diameter (BPD) were made from the 18‐20th week (early in the study the first BPD measurements were obtained at 28 weeks). Growth curves of BPD were constructed for each week, separately for the smoking groups (49 %) and the non‐smoking group (51 %) by compiling 5714 BPD measurements, only women subsequently delivered between 266 and 294 days after the last menstrual period were included to avoid erroneously skewed growth profiles. The BPD increased faster during gestation in the non‐smoking group, the difference from the smoking group being significantly apparent from the 28th week onwards and positively correlated to the average number of cigarettes smoked. There was a preponderance within the non‐smoking group for marriage, and preeclampsia; and within the smoking group for abruptio placentae, pre‐term delivery, low birth‐weight, short birth‐length, small head circumference, and small‐for‐gestational‐age. The low birth‐weights were independent of maternal prepregnant weight and weight gain. Compared with data obtained in a similar study in the same community, 1963/64, the prevalence of smoking among pregnant women had increased from 44 % to 49 %. The present study demonstrates the early onset of intrauterine growth retardation in pregnancies of smoking mothers. The results suggest that the fetal growth retardation is a direct pharmacological effect on the fetus rather than an influence resulting from nutritional deprivation and points to appearent inefficiency of the programme deterring women from smoking.

An improved echo-tracker for studies on pulse waves in the fetal aorta

Publisher Summary This chapter presents comments on an improved echo-tracker for studies on pulse waves in the fetal aorta. In clinical studies, pulse wave velocity (PWV) has usually been investigated over long segments of the arterial tree, which, therefore, have come to include several types of vessels with different characteristics. The available methods for measuring pulse waves have previously been based upon volume changes caused by pressure pulsations. The pulse wave method for the investigation of the vascular system differs in many respects from the presently available diagnostic ultrasound methods, that is, the combinations of Doppler ultrasound and real-time ultrasonography. First, it is possible, non-invasively, to obtain information about quite new physiological parameters, such as the segmental pulse wave velocity and thereby the regional elastic properties of the vascular system. Second, conventional diagnostic ultrasound is extremely sensitive to the exact positioning of the ultrasound transducer for reproducible and consistent results. The velocity of the propagation of the pulse waves created by ventricular ejection represents an important parameter in the analyses of the behavior of the arterial tree. However, its clinical value has until now been limited because of the practical difficulties in making adequate pulse wave recordings. With the introduction of the new dual, auto-lock echo-tracker, pulse wave velocity measurements using radial dilatation as a parameter is, for the first time, within the reach of becoming a clinical routine.

Increased stiffness of the aorta in children and adolescents with insulin-dependent diabetes mellitus

An ultrasonic system fitted with echo-tracking circuits was used to investigate the mechanical properties of the descending aorta in children and adolescents with insulin-dependent diabetes (IDDM). Seventy-six children and adolescents (aged 5-20 years) with uncomplicated diabetes and 75 age- and gender-matched healthy controls were examined. All subjects were normotensive. A nonlinear correlation between the stiffness index of the aorta and the age was found in both the diabetic (r = 0.47; P < 0.001) and control group (r = 0.57; P < 0.001). The stiffness index was higher among the diabetic subjects as compared to the controls (P < 0.01). No difference regarding stiffness of the aorta was found between genders in either of the groups. No correlation was observed between the stiffness index and the duration or degree of the metabolic control of diabetes. Our study demonstrated an increased stiffness of the aorta in children and adolescents with IDDM at the stage when no vascular complications were detected clinically.

PHYSIOLOGICAL CHARACTERISTICS OF DIAMETER PULSES IN THE FETAL DESCENDING AORTA

Abstract. A study was performed to establish the dynamic behavior in situ of the descending aorta in the human fetus. The pulsatile movements of the vessel walls were recorded in 36 clinically normal fetuses using a real‐time phase‐locked ultrasonic system measuring echo movements with high spatial and temporal resolution. The mean amplitude of the diameter pulsations was similar in the 28th 35th week to that in the 36th 40th week but, as the apparent diastolic diameter increased, the pulse‐elicited increment of the cross‐sectional area was 29% larger in the older group. The diastolic diameter decreased (p<0.001) and the amplitude of the diameter pulsation increased (p<0.001) with prolongation of the previous beat interval. The diameter pulse velocity was positively correlated to gestational age (p<0.001), ranging between 1.35 and 2.89 m/sec. The incremental phase of the pulse curve diminished in duration with increasing distance from the heart (p< 0.001) and with decreasing duration of the previous beat interval (p< 0.001). The maximum slope of the incremental phase was higher in the more distal part of the aorta (p<0.001). The study demonstrates that the diameter pulses contain useful information on the cardiovascular dynamics and provides evidence that the Frank‐Starling mechanism is effective also in the human fetus.

Blood flow velocity and pulsatile diameter changes in the fetal descending aorta: A longitudinal study

Blood flow velocity and pulsatile diameter changes in the fetal descending aorta were measured subsequently with pulsed Doppler ultrasonography and phase-locked echo-tracking technique, respectively. Blood flow velocity and pulse-wave curves with equal beat-to-beat intervals were synchronized by external fetal electrocardiogram. The systolic increase in blood flow velocity and in vessel diameter started simultaneously. The velocity peak preceded the diameter peak by a significant margin (p in the range 0.0001 to 0.0014). The time interval was more pronounced in the thoracic than in the abdominal part of the aorta and was slightly smaller near term. The effective diameter, calculated from the synchronized integrals of the blood flow velocity and the diameter curves, was significantly greater (p in the range 0.0001 to 0.0016) than the mean diameter. The difference tended to decrease with advancing gestational age and was more pronounced in the thoracic than in the abdominal aorta. The maximum error incurred by the use of nonsimultaneous measurements of blood flow velocity and vessel diameter when calculating volume blood flow was found to be less than 8% and thus probably of little practical importance.

ACUTE EFFECTS OF MATERNAL SMOKING ON FETAL HEART BEAT INTERVALS

Abstract. The purpose of this study was to analyse the acute effects of maternal cigarette smoking on the fetal heart beat intervals and their variability during the last trimester of a normal gestation. The fetal heart beat intervals were monitored continuously by abdominal electrocardiography for 60 min before and 60 min after smoking in 10 pregnant women. The mean intervals, their long‐term variability (SD) and short‐term variability (standard deviation of interval differences (SDID)), calculated for 30‐sec periods, showed a steady state before smoking. During the control period, the mean beat interval was negatively correlated with daily cigarette consumption and the short‐term variability was positively correlated with the maternal plasma nicotine level. After smoking, the mean beat interval and the short‐term variability decreased transiently, the values of both these parameters being positively correlated with the maternal nicotine values before smoking. The acute response of fetal heart beat intervals and their variability to one cigarette is distinct but transient, and the results suggest that the effects are modified by the chronic smoking habits of the women.

Acute Responses to Maternal Smoking of the Pulsatile Movements in Fetal Aorta

Abstract. In order to further characterize the acute cardiovascular responses of the human fetus to maternal smoking, 17 women in late pregnancy were studied after smoking a single cigarette. The pulsations of the fetal descending aorta were recorded by means of an ultrasound scanner connected to a phaselocked echotracking instrument; the fetal ECG was recorded from abdominal electrodes. Both the level and the waveform of the diameter pulse curve changed typically 3 25 min after the onset of smoking, concomitant with an increase in maternal and fetal heart rate. Apparent diastolic diameter and pulse amplitude increased, while the ascending part of the curve increased in slope and decreased in duration; the late decremental velocity was reduced. The propagation time from the onset of the fetal Q‐wave to the arrival of the pulse wave at the site of recording was reduced. This study demonstrates for the first time the acute effects of maternal smoking on the pulsatile dynamics of fetal vessel walls, and the method suggests the possibility of estimating changes in the contractility of the fetal heart and theafteroad in the fetal circulation.