Supine and standing heart rate and heart rate responses to deep breathing ... but the pregnancy-induced increase in heart rate was less in the diabetic women.
E
ffect of Pregnancy on Autonomic Nervous Function and Heart Rate in Diabetic and Nondiabetic Women
K. E. JUHANI AIRAKSINEN, MD, PASI I. SALMELA, MD, MARKKU J. IKAHEIMO, MD, PERTTI KIRKINEN, MD, MARKKU K. LINNALUOTO, MSc, AND JUHA T. TAKKUNEN, MD
Supine and standing heart rate and heart rate responses to deep breathing and standing up (the 30-to15 ratio), indices of autonomic nervous function, were measured during each trimester and postpartum in 25 women with insulin-dependent diabetes and 10 nondiabetic women. The groups did not differ with respect to autonomic function in the basal state (postpartum), and the heart rate response to deep breathing diminished progressively in both groups during pregnancy, although the change tended to be less pronounced in the diabetic women. The 30-to-15 ratio did not alter significantly during pregnancy. The diabetic women had a higher supine heart rate than the healthy women in the basal state, but the pregnancy-induced increase in heart rate was less in the diabetic women. Thus, the reversible diminution of heart rate response to deep breathing during pregnancy is a physiological finding and does not denote development of autonomic nervous dysfunction. Second, the increase in heart rate, a primary cardiovascular adjustment to pregnancy, seems to be blunted in diabetic women. Diabetes Care 10:748-51, 1987
T
he maternal circulation adjusts during pregnancy to meet the increasing requirements of the growing fetus. Blood volume and cardiac output increase progressively, reaching levels during the third trimester that average 30-40% above the nonpregnant values (1—5). These changes are accompanied by a decrease in systemic vascular resistance, because the placenta forms a vascular bed with a low circulatory resistance to ensure adequate fetal blood flow under varying hemodynamic circumstances (1). Autonomic nervous function plays a fundamental role in adapting the heart and circulation to various situations, presumably including pregnancy. Although the effects of pregnancy on cardiac output are well documented, there is little information concerning autonomic nervous function even during normal pregnancy (6,7). Because diabetes is often associated with abnormalities of autonomic nervous function, we decided to investigate the effects of pregnancy in diabetic and nondiabetic women. PATIENTS AND METHODS
Patients. Thirty-three women with insulin-dependent diabetes mellitus initially participated in the study. They were 748
consecutive patients admitted to the Department of Obstetrics and Gynecology, Oulu University Central Hospital, during the first trimester of pregnancy. However, 8 dropped out before the postpartum visit due to nursing problems and long distances between home and hospital. Thus, 25 diabetic women completed the whole study protocol. They ranged in age from 19 to 40 yr (mean 27), and 11 of them were primiparous. The mean duration of diabetes was 15 yr (range 2—31). None had evidence of heart disease on the basis of a medical history, physical examination, and 12-lead electrocardiogram. Two patients had mild hypertension, which was easily controlled with clonidine during the pregnancy, and four developed mild hypertension, which was treated with clonidine late in the pregnancy. None of the patients took any other drugs that might affect cardiac or autonomic nervous function. Thirteen patients had retinal changes; 3 of them had proliferative retinopathy. Four patients had proteinuria. None had symptoms of painful peripheral neuropathy. All patients were C-peptide negative in the glucagon-stimulation test. Fifteen diabetic women were on multiple daily insulin injections, 8 were on a conventional twice-daily insulin-injection regimen, and 2 used continuous subcutaneous insulininfusion pumps. All diabetic women monitored their blood glucose at home with a 7- to 9-point profile 2 or 3 days per
DIABETES CARE, VOL. 10 NO. 6, NOVEMBER-DECEMBER 1987
AUTONOMIC NERVOUS FUNCTION AND DIABETES/K. E. J. AIRAKSINEN AND ASSOCIATES
TABLE 1 Blood pressure and glycemic control of diabetic and control women during pregnancy and postpartum Trimester
Systolic blood pressure (mmHg) Diabetic Control Diastolic blood pressure (mmHg) Diabetic Control Mean 24-h blood glucose (mM) Diabetic HbA, (%) Diabetic
1st
2nd
3rd
Postpartum
120 ± 12 113 ± 11
117 ± 11 115 ± 12
124 ± 16* 111 ± 7
128 + 20 116 ± 18
76 ± 10 71 ± 9
74 ± 10 72 ± 8
80 ± 13 71 ± 7
84 ± 12 78 ± 19
6.1 ± 1.6
5.6 ± 1.5
5.6 ± 1.5
9.6 ± 1.1
9.0 ± 1.7
9.0 ± 1.9
10.8 ± 2.5
Values are means ± SD. ' P = .01 compared with control group.
week. The optimal goal for blood glucose values was
