Is growth hormone good for the heart?

The influence of growth hormone status on physical impairments, functional limitations, and health-related quality of life in adults

The availability of recombinant human GH and somatostatin analogs has resulted in widespread treatment for adults with GH deficiency (GHD) and those with GH excess (acromegaly). Despite being at opposite ends of the spectrum in terms of their GH/IGF-I axis, both of these populations experience overlapping somatic impairments. Adults with untreated GHD have low circulating levels of IGF-I that manifest as altered body composition with increased fat and reduced lean body and skeletal muscle mass. At the other end of the spectrum, adults with GH excess, who have elevated levels of IGF-I, also have altered body composition. Impairments that result from disorders of either GHD or GH excess are both associated with increased functional limitations, such as reduced ability to walk quickly for prolonged periods, and poorer health-related quality of life (HR-QoL). Adults with untreated GHD and GH excess both commonly complain of excessive fatigue that seems to be associated more with impaired aerobic than muscular performance. Several studies have documented that administration of GH or somatostatin analogs to adults with GHD or GH excess, respectively, ameliorates abnormal biochemical profile and the associated somatic impairments. However, whether these improvements translate into improved physical function in adults with GHD or GH excess remains largely unknown, and their impact on HR-QoL controversial. Review of placebo-controlled trials to date suggests that GH and somatostatin analogs have greater effects on gas exchange and aerobic performance than as anabolic agents on skeletal muscle mass and function. Future investigations should include dose-response studies to establish the optimal combination of pharmacological agents plus exercise required to improve not only biochemical markers but also physical function and HR-QoL in adults with GHD or GH excess.

Cardiovascular anomalies in children and young adults with Ullrich-Turner syndrome the Erlangen experience

BACKGROUND

Females with Ullrich-Turner syndrome (UTS) have typical clinical features such as short stature, ovarian failure, visible dysmorphic stigmata, and abnormalities in different organs such as kidney or heart.

HYPOTHESIS

The aim of the present study was to analyze the distribution, prevalence, and relative risk of cardiovascular anomalies (CVA) in females with Ullrich-Turner syndrome (UTS) seen at one single center compared with that of the regional Bavarian population.

METHODS

The associations between CVA and karyotype were determined. In all, 117 girls and women with UTS, aged between 3 and 43 years (median 17.4 years) were studied retrospectively. The detailed cardiologic status including echocardiography was available in all patients. The prevalences of each cardiovascular anomaly were determined. On the basis of published epidemiologic data of CVA in Bavarian children, we assessed the relative risks of each CVA.

RESULTS

Thirty-five (29.9%) girls with UTS had at least one CVA. In all of these CVAs, coarctation of the aorta and bicuspid aortic valve occurred most often (18.5% each). The aortic malformations represented over two-thirds of all CVA (72.8%), whereas anomalies of the septum (8.6%), mitral valve (6.2%), pulmonary veins (4.9%), and other locations together accounted for the other third. Bicuspid aortic valve and partial anomalous pulmonary venous drainage were associated with the highest relative risk (RR) (3603 and 1293, respectively) compared with the Bavarian population. The overall RR of CVA was 48.7. Of the 117 girls and women examined, 64 (54.7%) had complete monosomy 45 X.

CONCLUSIONS

Our data demonstrate that about every third female with UTS is affected with at least one CVA, mainly left sided and associated with aortic structures. Our results underline the necessity of thorough cardiologic evaluation.

Cardiac IGF-I manipulation by growth hormone following myocardial infarction

Evidence of a role for growth hormone (GH) in cardiac structure and function has been derived from studies of patients suffering either GH excess or deficiency, both of which may lead to reduced life expectancy. The role of GH in the ischaemic heart, however, is less than clear. We therefore investigated the effect of 30 days GH treatment in sheep with myocardial infarction. GH treatment significantly increased circulating IGF-I levels (P<0.01), heart weight (P<0.01), and cardiomyocyte cross-sectional area (P<0.001). IGF-I mRNA in peri-infarct cardiac tissue also increased significantly (P<0.05). We conclude that post-infarct GH treatment increases circulating and cardiac IGF-I levels, resulting in significant cardiomyocyte hypertrophy. This increase in cardiomyocyte size appears to correlate with local IGF-I expression rather than plasma IGF-I levels.

Growth hormone release during acute and chronic aerobic and resistance exercise: recent findings

Exercise is a potent physiological stimulus for growth hormone (GH) secretion, and both aerobic and resistance exercise result in significant, acute increases in GH secretion. Contrary to previous suggestions that exercise-induced GH release requires that a "threshold" intensity be attained, recent research from our laboratory has shown that regardless of age or gender, there is a linear relationship between the magnitude of the acute increase in GH release and exercise intensity. The magnitude of GH release is greater in young women than in young men and is reduced by 4-7-fold in older individuals compared with younger individuals. Following the increase in GH secretion associated with a bout of aerobic exercise, GH release transiently decreases. As a result, 24-hour integrated GH concentrations are not usually elevated by a single bout of exercise. However, repeated bouts of aerobic exercise within a 24-hour period result in increased 24-hour integrated GH concentrations. Because the GH response to acute resistance exercise is dependent on the work-rest interval and the load and frequency of the resistance exercise used, the ability to equate intensity across different resistance exercise protocols is desirable. This has proved to be a difficult task. Problems with maintaining patent intravenous catheters have resulted in a lack of studies investigating alterations in acute and 24-hour GH pulsatile secretion in response to resistance exercise. However, research using varied resistance protocols and sampling techniques has reported acute increases in GH release similar to those observed with aerobic exercise. In young women, chronic aerobic training at an intensity greater than the lactate threshold resulted in a 2-fold increase in 24-hour GH release. The time line of adaptation and the mechanism(s) by which this training effect occurs are still elusive. Unfortunately, there are few studies investigating the effects of chronic resistance training on 24-hour GH release. The decrease in GH secretion observed in individuals who are older or have obesity is associated with many deleterious health effects, although a cause and effect relationship has not been established. While exercise interventions may not restore GH secretion to levels observed in young, healthy individuals, exercise is a robust stimulus of GH secretion. The combination of exercise and administration of oral GH secretagogues may result in greater GH secretion than exercise alone in individuals who are older or have obesity. Whether such interventions would result in favourable clinical outcomes remains to be established.

Further delineation of cardiac abnormalities in Costello syndrome

We review the cardiac abnormalities in 94 patients (27 new, 67 literature) with Costello syndrome, an increasingly recognized syndrome consisting of increased birth weight, postnatal growth retardation, and distinctive facial, skin, and musculoskeletal features (MIM 218040). A cardiac abnormality was found in 59 (63%) patients, with each of three categories occurring in approximately one-third of patients. A cardiovascular malformation (CVM) was noted in 30%, typically pulmonic stenosis (46% of those with a CVM). Cardiac hypertrophy was reported in 34%, which involved the left ventricle in 50% and was usually consistent with classic hypertrophic cardiomyopathy (HCM). A variety of rhythm disturbances were reported in 33%. Most (74%) were atrial tachycardia that was reported as supraventricular, chaotic, multifocal, or ectopic. Of 31 patients with a rhythm abnormality, 22 (68%) had an additional abnormality, i.e., CVM (4), cardiac hypertrophy (12), or both (6). Nine patients had isolated dysrhythmia, five (56%) of whom died. All of the 12 (13%) patients who died had a cardiac abnormality. One patient died of embryonal rhabdomyosarcoma, but in the remainder, a cardiac cause of death could not be disproved. All patients with Costello syndrome need a baseline cardiology evaluation with echocardiography and Holter monitoring. Additional prospective evaluations, even in patients without apparent cardiac abnormalities, would be prudent, although data are insufficient to propose a specific schedule.

Change of serum growth factors in infants with isolated ventricular defect undergoing surgical repair

BACKGROUND

Despite increasing clinical use and recent evidence that insulin-like growth factor-1 (IGF-1), insulin-like growth factor binding protein-3 (IGFBP-3), and human growth hormone (hGH) target the heart, the clinical manifestations following the change in the serum growth factors in infants with isolated ventricular septal defect (VSD) undergoing surgical repair have not been clearly defined.

METHODS

Twenty normal infants (group I) and 44 consecutive infants with echocardiography established isolated VSD (aged from 3 months to 1 year; body weight from 6.0 +/- 1.8 kg to 8.2 +/- 1.6 kg) were investigated. Among 44 infants with VSD, 20 with shunt fraction, Qp/Qs < or = 1.5 were free of symptoms of congestive heart failure (group II); 24 with shunt fraction, Qp/Qs > or = 2.0 were in congestive heart failure (group IIIa); and 20 of these 24 infants had undergone VSD repair 6 months before their second study (group IIIb). Serum IGF-1, IGFBP-3, and hGH factors were determined by enzyme-linked immunosorbent assay using a monoclonal antibody.

RESULTS

The serum levels of IGF-1, IGFBP-3, and hGH factors were 111.9 +/- 2.3 ng/mL, 22.0 +/- 2.3 ng/mL, and 3.6 +/- 0.7 microIU/mL for group I; 63.8 +/- 8.2 ng/mL, 17.1 +/- 1.6 ng/mL, and 4.1 +/- 1.2 microIU/mL for group II; 24.0 +/- 2.6 ng/mL, 9.4 +/- 0.7 ng/mL, and 14.7 +/- 3.5 microIU/mL for group IIIa; 79.4 +/- 12 ng/mL, 20.3 +/- 1.3 ng/mL, and 4.3 +/- 0.7 microIU/mL for group IIIb. In comparison to group I, the decrease in serum levels of IGF-1 and IGFBP-3 in groups II and IIIa were statistically significant (in group II 43% and 32%, p < 0.05; in group IIIa 79% and 37%, p < 0.01). Also the increase in serum level of hGH concentration in group IIIa was significant (increased threefold, p < 0.01). Interestingly, the change in serum levels of IGF-1, IGFBP-3 (decrease), and hGH (increase), returned to the normal range of serum levels after VSD repair in group IIIb. All congestive heart failure symptoms subsided in group IIIb during follow-up.

CONCLUSIONS

Improvement in serum levels of IGF-1, IGFBP-3, and hGH were identified in infants with VSD after surgical repair.

Ventilation threshold as a measure of impaired physical performance in adults with growth hormone excess

OBJECTIVE

Fatigue is a prominent symptom among patients with GH excess and acromegaly. Identifying the physiological basis of such complaints and obtaining objective measures to quantify their severity remains an ongoing challenge. We investigated whether submaximal measures of aerobic performance can be used to assess GH excess-associated fatigue objectively.

DESIGN AND PATIENTS

To investigate this possibility we examined the relation between physical function and physical capacity in 12 patients with active acromegaly and persistent fatigue before and after 3 and 6 months of treatment with the long-acting somatostatin analogue octreotide (LAR(R)).

MEASUREMENTS

Heart rate (HR) and rating of perceived exertion (RPE using Borg's 10-point scale) were measured during a 160-metre self-paced walk test (SPW). Maximum oxygen uptake (VO2max) and ventilation threshold (VeT: a measure of work rate when breathlessness develops) were measured during a progressive treadmill test to fatigue or symptom-limited maximum. The Profile Of Mood States questionnaire (POMS) was used to quantify subjective feelings of fatigue and vigour. Morning fasting levels of GH and IGF-I were measured using immunoassay of serum samples.

RESULTS

SPW speed at a fast pace of 1.69 +/- 0.18 m/s was achieved with higher than normal HR (112 +/- 15/min; normal = 102) and RPE (2.4 +/- 1.2). Similar to GH-deficient adults, VO2max (22.6 +/- 6.4 ml.kg-1.min-1; normal approximately 30 ml.kg-1.min-1) and VeT (13.1 +/- 2.9 ml.kg-1.min-1; predicted normal approximately 16 ml.kg-1(min-1) were low. However, VeT occurred at a normal fraction of VO2max (VeT/VO2max = 0.58). VeT was significantly increased and plasma IGF-I levels reduced following 3 and 6 months of octreotide LAR(R) treatment. Reduction in circulating IGF-I levels was correlated with improvement in reported vigour (r = 0.85) and VeT (r = 0.65) (P < 0.05).

CONCLUSIONS

Our findings demonstrate impairment in physical function and physical capacity consistent with the perception of increased fatigue among acromegalic patients. These objective measures of compromised physical function are similar to the changes that we have reported previously in adults with GH deficiency. Taken together, these data suggest that a narrow window for GH/IGF-I levels is required to maintain optimal physical function.

Effects of rhIGF-I and insulin-induced hypoglycaemia on cardiovascular parameters recorded with telemetry in the conscious dog

Using telemetry, the effects on cardiovascular parameters after single intravenous administration (0.5 mg/kg) of recombinant human insulin-like growth factor-I (rhIGF-I) were studied in conscious and unrestrained dogs. Insulin (1.1 IU/kg) was used as a reference compound. Telemetry transmitters were implanted subcutaneously with a pressure catheter in the femoral artery and electrodes for ECG subcutaneously. Cardiovascular effects and changes in blood glucose levels induced with rhlGF-I were similar to those induced with insulin. Heart rate increased continuously for about 90 min. after treatment, regardless of compound. Thereafter, heart rate slowly decreased but did not fully reach predose values 4 hr after treatment. Both systolic and diastolic blood pressure decreased continuously for about 90 min. and remained low for up to 4 hr after treatment. Treatment with rhIGF-I or insulin did not influence dp/dt values. Treatment with glucose intravenously to abolish the rhIGF-I-induced hypoglycaemia reduced the heart rate, but caused a substantial increase in dp/dt and a slight increase in blood pressure. RhIGF-I and insulin induced an almost identical onset and degree of hypoglycaemia. Blood glucose reached a minimum level 1 hr after treatment and was almost returned to normal 4 hr after treatment. There was an increase in the amplitude of the T-waves, though this effect occurred earlier and was longer lasting with insulin than with rhIGF-I. After 4 hr, the T-wave amplitude was normal with rhIGF-I but remained high with insulin. These T-wave effects were probably due to an increase in the transport of potassium or calcium since they decreased in plasma. This suggests that the effects of rhIGF-I and insulin are highly comparable and that the cardiovascular changes induced by rhIGF-I are likely caused by its insulin-like activity. As shown by the recorded cardiovascular responses induced by rhIGF-1 and insulin, the telemetric recording system makes it possible to evaluate the effects of different drugs in a continuous way that is not possible with conventional techniques. This new telemetric technique can be of significant importance in the process of future drug development.

[The Influence of the growth hormone in the profile of blood pressure. Results in adult patients with deficiency in this hormone]

INTRODUCTION AND OBJECTIVES

There is an increasing interest in the relationship between the growth hormone (GH) and the heart since the GH has an important inotropic effect and its use has been tested in patients with severe systolic dysfunction. However, cardiovascular diseases are the main cause of increased morbimortality observed in patients with acromegaly. Growth hormone deficiency has been related to different clinical findings depending on the age of onset. Recent studies have demonstrated that GH deficiency in adults is associated with alterations in blood pressure. The aim of our study was to assess the influence of GH in blood pressure.

PATIENTS AND METHODS

We studied 14 adult patients with GH deficiency and 15 healthy subjects, matched for sex and age. The diagnosis of GH deficiency was based on GH response to intravenous insulin tolerance test < 5 ng/ml and IGF-1 levels lower than the normal limit for each age group. In all the patients 24-hour Holter blood pressure monitorization was performed in addition to a treadmill test and echographic evaluation.

RESULTS

All patients showed normal systolic and diastolic function in the echocardiographic study. Only one patient had an increased left ventricular mass. Blood pressure was lower in the patients than in the control subjects (p < 0.05). Moreover, the difference remained significant when analysis was based on the time of day. However, the patients showed normal blood pressure response to the effort test with a mean increase of 60%. The length of the exercise on the treadmill test was shorter in the subgroup of GH deficient patients.

CONCLUSIONS

Lower systolic blood pressure was observed in GH deficiency patients. The patients studied did not show structural heart alterations. Blood pressure and chronotrophic response to the effort test were similar in both groups.

M-mode echocardiographic evaluation of systolic function, LV volume and mass in children on growth hormone therapy

Since abnormal endogenous growth hormone (GH) secretion in adults is associated with cardiac dysfunction, it is important to ensure that GH therapy in children and adolescents does not cause similar effects. Forty-two growth hormone-deficient children (Group 1) (19 girls, 23 boys) were evaluated. Six girls and seven boys were prepubertal with a mean age of 6.65 yr (range 4.37-9.73 yr). Twenty-nine were pubertal (13 girls, 16 boys), mean age 13.57 yr (range 10.08-16.76 yr). The patients had been on long-term GH therapy for 34.97 +/- 18.78 months with an average weekly dose of 17.61 IU/m2/wk. The mean height SDS was -2.85 +/- 1.22 for boys and -2.5 +/- 0.64 for girls at the onset of therapy, and at the time of examination -1.8 +/- 1.32 for the boys and 1.87 +/- 0.94 for the girls. Thirty-four normal control subjects (Group 2) matched for age, sex and body size were also studied. Left ventricular volume (LV), mass and systolic function [shortening fraction (FS)] were evaluated by two-dimensional guided M-mode echocardiography. Blood pressure was also measured. No differences in blood pressure were observed between patients and controls. There was no correlation of GH dose and duration of therapy with LV measurements. No significant differences were found between Group 1 and Group 2. These observations suggest that long term administration of GH does not produce adverse cardiac effects in GH deficient children. Nevertheless, longer follow-up studies are still needed to confirm the safety of long-term rhGH treatment.

Lack of effects of recombinant human growth hormone in a child with a complex cardiovascular malformation and dilated cardiomyopathy

Recent studies have suggested the beneficial effects of GH treatment in patients with dilated cardiomyopathy. We have treated with recombinant human growth hormone (rhGH) a 6-year-old female with a complex congenital heart defect (severe tricuspid hypoplasia and malposition of the great arteries), who developed a progressive dilated cardiomyopathy of unknown etiology. rhGH treatment (0,1 U/kg/day, for 3 months) did not improve cardiac function, nor clinical symptoms, although we have no clear explanations for this. However, a trial with rhGH may be offered to children with dilated cardiomyopathy and waiting for heart transplantation.

Effect of short-term medroxyprogesterone acetate on left ventricular mass: role of insulin-like growth factor-1

Previous studies using 17beta-estradiol and medroxyprogesterone acetate (MPA) have shown that hormone replacement therapy (HRT) increases left ventricular mass (LVM). To determine if insulin-like growth factor-1 (IGF-1) is associated with the increase in LVM, we measured IGF-1 and IGF-binding protein-3 (IGFBP-3) levels in 19 postmenopausal women before and after 8 weeks of oral treatment with MPA 5 mg/d. LVM was measured by two-dimensional echocardiography. Changes in IGF-1, IGFBP-3, and LVM from baseline were analyzed by paired ttest. Regression analysis was used to determine if changes in the IGF-1 axis with MPA treatment affect the increase in LVM. LVM increased 4.4% during the study (P = .006 vbaseline). IGF-1 increased 17% with MPA (P = .008), whereas IGFBP-3 did not change. The IGF-1/IGFBP-3 ratio increased 16.8% (P = .0003). Regression analysis of LVM with IGF-1, IGFBP-3, and the IGF-1/IGFBP-3 ratio suggested that IGF-1 during MPA therapy explains 2.4% and the IGF-1/IGFBP-3 ratio explains 3.2% of the variation in LVM. There was no effect of IGFBP-3 on LVM. Most of the variation in LVM with MPA (90.5%) was explained by baseline LVM. The IGF-1/IGFBP-3 ratio on MPA treatment was inversely related to the change in LVM: women with a lower LVM at baseline had the greatest increase in LVM with MPA. These findings suggest that MPA increases IGF-1 and LVM. Because the increase in IGF-1 with MPA treatment explains a fraction of the increase in LVM, other mechanisms must also be operative.

Low blood glucose levels and other complications during growth hormone supplementation in sepsis

Blood glucose levels in the high normal range or even moderate hyperglycemia is the expected profile in septic postoperative patients receiving high-calorie enteral alimentation. The addition of growth hormone as an anabolic agent should additionally reinforce this tendency. In a cancer patient undergoing partial gastrectomy with lymphadenectomy and suffering from postoperative subphrenic abscess and prolonged sepsis, tube feeding (38.3 kcal/kg/day) and growth hormone (0.17 IU/kg/day) were simultaneously administered for 25 days. Blood glucose levels were in the lower limits of the normal range before growth hormone introduction, and continued with a similar tendency during most of the therapeutic period. Two additional complications, namely heart arrest and peripheral edema, were documented during the same period. It is concluded that sepsis was the most likely mechanism for low glucose values, and that high-calorie enteral diet and growth hormone supplementation did not prevent that result. It is uncertain whether heart arrest was due to the drug, but its association with peripheral edema is well documented in clinical series.

Congenital heart disease in patients with Turner's syndrome. Italian Study Group for Turner Syndrome (ISGTS)

OBJECTIVE

There is a high prevalence of congenital heart defects in patients with Turner's syndrome. Few studies have reported echocardiographic data in unselected patients according to the different chromosomal patterns. The aim of our study was to evaluate a large series of patients with Turner's syndrome, comparing these data with those of the general population.

METHODS

Five hundred ninety-four patients with Turner's syndrome, aged 1 month to 24 years, in the Italian Study Group for Turner Syndrome underwent full cardiologic evaluation. Karyotype distribution was: 45,X (54%), X-mosaicism (13%), and X-structural abnormalities (33%).

RESULTS

The prevalence of cardiac malformations was 23%. Bicuspid aortic valve (12.5%), aortic coarctation (6.9%), and aortic valve disease (3.2%) were the most prevalent malformations. In comparison with the general population, partial anomalous pulmonary venous drainage had the highest relative risk. A correlation was found between type of congenital heart defect and karyotype. The patients with 45,X karyotype had the greatest prevalence of partial anomalous pulmonary venous drainage and aortic coarctation, whereas bicuspid aortic valve and aortic valve disease were more common in the patients with X-structural abnormalities. The patients with severe dysmorphic signs showed a significantly higher relative risk of cardiac malformations.

CONCLUSION

X-linked factors may be involved in determining cardiac defects in Turner's syndrome.