Endocrine predictors of acute hemodynamic effects of growth hormone in congestive heart failure

Hormone treatments in congestive heart failure

The common ultimate pathological feature for all cardiovascular diseases, congestive heart failure (CHF), is now considered as one of the main public health burdens that is associated with grave implications. Neurohormonal systems play a critical role in cardiovascular homeostasis, pathophysiology, and cardiovascular diseases. Hormone treatments such as the newly invented dual-acting drug valsartan/sacubitril are promising candidates for CHF, in addition to the conventional medications encompassing beta receptor blockers, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and mineralocorticoid receptor antagonists. Clinical trials also indicate that in CHF patients with low insulin-like growth factor-1 or low thyroid hormone levels, supplemental treatment with growth hormone or thyroid hormone seems to be cardioprotective; and in CHF patients with volume overload the vasopressin antagonists can relieve the symptoms superior to loop diuretics. Furthermore, a combination of selective glucocorticoid receptor agonist and mineralocorticoid receptor antagonist may be used in patients with diuretic resistance. Finally, the potential cardiovascular efficacy and safety of incretin-based therapies, testosterone or estrogen supplementation needs to be prudently evaluated in large-scale clinical studies. In this review, we briefly discuss the therapeutic effects of several key hormones in CHF.

One-year GH replacement therapy reduces early cardiac target organ damage (TOD) in adult GHD patients

Hypopituitarism reduces life expectancy and increases the risk of cardiovascular and cerebrovascular diseases, as well as death. Abnormalities in the cardiovascular system may be independently related to GH deficiency (GHD). The aim of this study was to prospectively investigate coronary flow reserve and diastolic function in GHD adult patients at diagnosis and after 1 year of GH replacement therapy. As control group, an age- and sex-matched population was chosen. All patients and controls were non-smokers, non-diabetic, and normotensive, with no history of vascular disease. 14 patients with adult-onset GHD and 17 controls represent the two study groups. Anthropometric data, blood pressure, lipid profile, glycosylated hemoglobin (HbA1c) and IGF-I plasma levels, coronary flow reserve (CFR), and LV diastolic function (evaluated by E/A) were collected in all subjects before and after 12 months of GH replacement therapy. Compared with controls, systolic and diastolic blood pressure and LDL cholesterol levels were significantly higher at baseline and return, comparable to controls after 1 year of GH replacement (GHRT). GHD patients showed a blunted CFR at baseline (P < 0.001) and a significant improvement after GHRT, returning to values comparable with those recorded in the control group. In addition, after therapy a significant (P < 0.001) improvement in E/A was recorded. One year of GH therapy improves CFR and E/A in the patient population analyzed, thereby encouraging the early start of GHRT.

GH and the cardiovascular system: an update on a topic at heart

In this review, the importance of growth hormone (GH) for the maintenance of normal cardiac function in adult life is discussed. Physiological effects of GH and underlying mechanisms for interactions between GH and insulin-like growth factor I (IGF-I) and the cardiovascular system are covered as well as the cardiac dysfunction caused both by GH excess (acromegaly) and by GH deficiency in adult hypopituitary patients. In both acromegaly and adult GH deficiency, there is also increased cardiovascular morbidity and mortality possibly linked to aberrations in GH status. Finally, the status of the GH/IGF-I system in relation to heart failure and the potential of GH as a therapeutic tool in the treatment of heart failure are reviewed in this article.

Growth hormone deficiency in treated acromegaly

Growth hormone deficiency (GHD) of the adult is characterized by reduced quality of life (QoL) and physical fitness, skeletal fragility, and increased weight and cardiovascular risk. Hypopituitarism may develop in patients after definitive treatment of acromegaly, but an exact prevalence of GHD in this population is still uncertain owing to limited awareness and the scarce and conflicting data available on this topic. Because acromegaly and GHD may yield adverse consequences on similar target systems, the final outcomes of some complications of acromegaly may be further affected by the occurrence of GHD. However, it is still largely unknown whether patients with post-acromegaly GHD may benefit from GH replacement. We review the diagnostic, clinical, and therapeutic aspects of GHD in adult patients treated for acromegaly.

Impact of adult growth hormone deficiency on metabolic profile and cardiovascular risk [Review]

Adult growth hormone deficiency (GHD) is a well defined clinical condition, which is characterized by abnormal body composition, impaired physical activity and decreased quality of life. In addition, in recent years, growing interest has been shown towards cardiovascular risks in adult patients affected by GHD. In this regard, GHD is widely known to be associated with increased mortality, likely due to the increase of risk factors, such as central obesity, impaired lipid and glucose profiles and other less-known risk factors, such as inflammatory cytokines, endothelial dysfunction and oxidative stress. However, very few papers have recently discussed this topic. In this review, the aim is to clarify this issue by discussing evidence regarding the effects of adult GHD on metabolic and cardiovascular profiles.

Acute growth hormone administration increases myoglobin expression and Glut4 translocation in rat cardiac muscle cells

OBJECTIVE

Oxygen (O2) and glucose are important energy sources for the heart. This study sought to investigate the effects of acute growth hormone (GH) administration on the expression of myoglobin (Mb) and Glut4 glucose transporter, two important limiting factors for O2 and glucose utilization for energy production, in cardiac muscle cells of treated rats.

METHODS

Male Wistar rats were sacrificed at 30, 45, 90 and 120 min after a single dose of intraperitoneal (ip) rat GH (1.5 mg/kg) or vehicle administration, and total RNA and protein (from whole cell or subcellular fractions) were extracted from cardiomyocytes (left ventricles) of these animals.

RESULTS

Acute GH injection led to a significant increase in both Mb mRNA and protein levels, and stimulated Glut4 protein translocation to the plasma membrane of cardiac cells.

CONCLUSIONS

These results suggest that GH exerts some of its effects on cardiomyocytes shortly after the first administration inducing the expression of proteins potentially involved in cardiac performance.

Failing heart of patients with type 2 diabetes mellitus can adapt to extreme short-term increases in circulating lipids and does not display features of acute myocardial lipotoxicity

BACKGROUND

Circulating lipid levels and myocardial lipid content (MyLC) is increased in type 2 diabetes mellitus. This may cause a state of lipotoxicity that compromises left ventricular function and aggravate heart failure. We investigated the relationship among circulating lipid levels, MyLC, and cardiac function together with the acute cardiac effects of high as opposed to low circulating free fatty acid (FFA) and triglyceride levels in patients with type 2 diabetes mellitus and heart failure.

METHODS AND RESULTS

Eighteen patients underwent 8-hour intralipid/heparin-infusion (high FFA) and hyperinsulinemic-euglycemic clamping (low FFA) in a randomized crossover-designed study. We applied magnetic resonance proton spectroscopy to measure MyLC. Cardiac function was assessed by advanced echocardiography, cardiopulmonary exercise, and MRI. MyLC correlated positively with circulating triglyceride (r=0.47; r(2)=0.22; P=0.003) and FFA (r=0.45; r(2)=0.20; P=0.001) levels and inversely with left ventricular ejection fraction (r=-0.54; r(2)=0.29; P=0.004). Circulating FFA concentrations differed between study arms (0.05 ± 0.04 mmol/L [low FFA] versus 1.04 ± 0.27 mmol/L [high FFA]; P<0.001) and MyLC increased from 0.78 ± 0.59% (low FFA) to 1.16 ± 0.73% (high FFA; P<0.01). Resting left ventricular ejection fraction and global strain did not differ between high and low FFA, whereas resting systolic mitral plane velocity (S'max) was highest during high FFA (3.6±0.8 cm/s [low FFA] versus 3.8±0.7 cm/s [high FFA]; P=0.02). Peak exercise capacity and oxygen consumption did not differ between the study arms, and neither did postexercise measurements of left ventricular ejection fraction, global strain, and S'max.

CONCLUSIONS

Our findings indicate that the failing heart of patients with type 2 diabetes mellitus can adapt to short-term extreme changes in circulating substrates and does not display features of acute myocardial lipotoxicity. Clinical Trial Registration- URL: http://www.clinicaltrials.gov. Unique identifier: NCT01192373.

Growth hormone therapy in congestive heart failure due to left ventricular systolic dysfunction: a meta-analysis

OBJECTIVE

To examine the efficacy and safety of recombinant human growth hormone (rhGH) therapy in congestive heart failure (CHF) by conducting a meta-analysis of clinical studies.

METHODS

We searched 3 literature databases (MEDLINE, EMBASE, and the Cochrane Register) for clinical studies of rhGH therapy in CHF due to systolic dysfunction and conducted a meta-analysis.

RESULTS

Therapy with rhGH appears to have beneficial clinical effects (weighted mean difference [95% confidence interval]) in CHF including improved exercise duration (1.9 min [1.1-2.7]), maximum oxygen consumption (2.1 mL x kg(-1) x min(-1) [1.2-3.0]), and New York Heart Association class (-0.9 [-1.5 to -0.3]). There were salutary hemodynamic effects of rhGH therapy, including increased cardiac output (0.4 L x min(-1) [0.1-0.6]) and decreased systemic vascular resistance (-177 dyn x s x cm(-5) [-279 to -74]). Among rhGH-treated patients, left ventricular (LV) ejection fraction improved (4.3% [2.2-6.4]). Despite increases in LV mass and wall thickness, there were no adverse effects on diastolic function. Subgroup analyses suggest that study design and treatment duration may influence some of the treatment effects. Most of the beneficial effects were driven by either uncontrolled or longer duration studies. Administration of rhGH therapy slightly increased the risk for ventricular arrhythmia; however, this finding was driven by a single small study.

CONCLUSION

rhGH therapy may have beneficial cardiovascular effects in CHF caused by LV systolic dysfunction. The possibility of proarrhythmia associated with rhGH therapy requires further study. Larger randomized trials with longer treatment duration are needed to fully elucidate the efficacy and safety of rhGH therapy in this patient population.

Cardiac effects of growth hormone treatment in chronic heart failure: A meta-analysis

CONTEXT

Experimental studies suggest that GH treatment may improve cardiovascular parameters in chronic heart failure (CHF). However, clinical trials involved small numbers of patients and did not allow a conclusion to be drawn on the effect of this treatment in humans.

OBJECTIVE

We systematically reviewed and analyzed all randomized controlled trials and open studies of sustained GH treatment in CHF.

STUDY SELECTION

Twelve trials were identified in three databases. We conducted a combined analysis of GH effects on cardiovascular parameters using the overall effect size to evaluate significance and computing the weighted mean differences with and without treatment to assess effect size.

DATA SYNTHESIS

GH treatment significantly modified morphological cardiovascular parameters [interventricular septum thickness, +0.55 (sd, 0.43) mm (P < 0.001); posterior wall thickness, +1.01 (0.44) mm (P < 0.01); left ventricle (LV) end-diastolic diameter, -2.02 (1.22) mm (P < 0.01); and LV end-systolic diameter, -5.30 (2.33) mm (P < 0.05)]; LV and systemic hemodynamics [LV end-systolic wall stress, -38.9 (13.3) dynes/cm(2) (P < 0.001); LV ejection fraction, +5.10 (1.74)% (P < 0.05); and systemic vascular resistance, +195.0 (204.5) dyn x sec(-1) x cm(-5) (P < 0.01)]; and functional parameters [New York Heart Association class, -0.97 (0.23) (P < 0.01); exercise duration, +103.7 (37.6) sec (P < 0.001); and maximal oxygen uptake, +2.48 (1.76) ml/kg x min (P < 0.01)]. Subgroup analysis and meta-regression showed significant relationships between the IGF-I response and GH treatment effects.

CONCLUSION

Our meta-analysis suggests that GH treatment improves several relevant cardiovascular parameters in patients with CHF. However, these results must be confirmed by a large randomized placebo-controlled trial on hemodynamic, morphological, and functional parameters during long-term high-dose GH treatment of patients with CHF.

Beneficial effects of high doses of growth hormone in the introduction and optimization of medical treatment in decompensated congestive heart failure

BACKGROUND

Optimizing oral therapy in patients with unstable decompensated and/or dobutamine-dependent congestive heart failure (CHF) is a challenge.

METHODS AND RESULTS

We investigated the effects of high doses of recombinant human growth hormone (GH) in 6 patients with cardiac cachexia and unstable decompensated CHF (5 dobutamine-dependent), including its influence in the optimization of oral CHF treatment. Patients received 8 IU of subcutaneous GH per day for median 26 (range 61) days. GH improved the systolic systemic blood pressure (SSBP, in mm Hg) from median 85 (range 34) to 100 (20) (p<.01), and the left ventricular (LV) ejection fraction (in %) from median 23 (range 22) (pretreatment) to 28 (18) (posttreatment) and 38 (28) (later) (p<.007). The NYHA functional class improved from IV to I in 2 patients, from IV to II in 3, and from IV to II-III in one. All patients were discharged from the hospital. It was possible in the hospital to initiate and after discharge to optimize long-term CHF treatment from 37.5 to 50 mg of carvedilol in 5 patients and with higher doses of captopril (from 50 to 150 mg) in all patients. Three patients are alive after 67, 75, and 11 months of follow-up. The remaining 3 patients died from a pulmonary abscess at 9 months, septicemia at 21 months, and progressive heart failure due to unplanned withdrawal of carvedilol at 36 months.

CONCLUSION

The use of GH in patients with decompensated CHF and cardiac cachexia provided clinical stability without the need for inotropic drugs permitting introduction of nonpreviously tolerated drugs. This could represent a new option for optimizing long-term CHF therapy and discharging hospitalized patients who are dobutamine-dependent.

Recombinant human growth hormone treatment for dilated cardiomyopathy in children

OBJECTIVE

Dilated cardiomyopathy (DCM) is one of the most common causes of heart failure among children and is often progressive despite maximal medical therapy. Heart failure is characterized by a number of neurohormonal abnormalities, including derangements in the growth hormone (GH)/insulin-like growth factor-1 (IGF-1) signaling axis. Decreased serum levels of GH, which acts on cardiac myocytes primarily through IGF-1, are associated with impaired myocardial growth and function, which can be improved with restoration of GH/IGF-1 homeostasis. In animal models and among human adults with heart failure attributable to DCM, treatment with GH results in acquisition of left ventricular (LV) mass and improved LV function, through a combination of mechanisms. We undertook this study to determine the effects of recombinant human GH on LV function and mass among children with stable LV dysfunction attributable to DCM.

METHODS

We performed a prospective, single-center, randomized, partially blinded, crossover trial among children 1 to 19 years of age with DCM and cardiac dysfunction of > or =6-month duration. After enrollment, patients were randomly assigned to receive treatment for 6 months with either conventional therapy (determined by the patient's primary cardiologist) plus recombinant human GH (0.025-0.04 mg/kg per day), administered as daily subcutaneous injections, or conventional therapy alone. Patients were then crossed over to the other treatment strategy for 6 months. The primary outcome measure was change in LV shortening fraction (SF). Other echocardiographic indices of LV function, somatic growth, and somatotropic/thyroid hormone levels were also monitored.

RESULTS

Only 8 of an intended 15 patients were enrolled, because of a combination of factors. Two patients withdrew during the study as a result of declining LV function requiring transplantation. LV SF did not change significantly during GH treatment, although both LV SF and LV SF z score were higher 6 months after cessation of GH treatment than at baseline. LV ejection fraction increased during GH therapy to a degree that approached significance. Height and weight percentiles for age increased significantly during GH therapy and remained higher 6 months after treatment. Annualized height velocity during GH treatment (13.7 +/- 3.3 cm/year, >97th percentile for all patients) was significantly higher than that after GH discontinuation (3.2 +/- 3.5 cm/year). Serum levels of IGF-1 and IGF-binding protein-3 were significantly higher after 6 months of GH treatment and 6 months after discontinuation of GH treatment than at baseline. There were no adverse events related to GH treatment.

DISCUSSION

In this prospective, single-center, randomized, partially blinded, crossover trial, recombinant human GH was administered to 8 pediatric patients with stable chronic heart failure secondary to DCM. Because of unanticipated difficulty enrolling eligible patients, the study was underpowered to detect changes in our primary outcome measure of the magnitude we projected. Nevertheless, we did observe several notable cardiovascular effects of GH treatment, including a trend toward improved LV ejection fraction during the course of GH treatment and significantly improved LV SF, SF z score, and LV end systolic stress z score 6 months after discontinuation of GH treatment (relative to baseline values). Given the fact that levels of IGF-1, the primary myocardial effector of GH signaling, remained significantly higher 6 months after GH treatment than at baseline, the improvement in LV functional indices 6 months after discontinuation of therapy may represent progression or perpetuation of a GH treatment effect. In addition to its cardiovascular effects, GH therapy was associated with significant acceleration of somatic growth. The benefits of GH were not associated with significant attributable side effects, although 2 patients developed progressive LV dysfunction during the study and underwent cardiac transplantation.

The Effects of Octreotide in Dilated Cardiomyopathy: An Open-label Trial in 12 Patients

Octreotide, a somatostatin analogue, has been found effective in the treatment of acromegalic cardiomyopathy. We investigated whether intermittent octreotide therapy had beneficial effects in patients with ischemic or idiopathic dilated cardiomyopathy, which are refractory to conventional therapy. Twelve patients with ischemic or idiopathic dilated cardiomyopathy were enrolled in the study. In addition to conventional treatment, octreotide (first 50 microg and then 25 microg three times per day for 4 days) was administered and repeated after 1, 2, and 3 months. The patients were evaluated 3 times, before and immediately after the first treatment and after 3 months of treatment, using echocardiography, exercise stress testing, ambulatory ECG, right ventricular catheterization, cardiac enzymes, and the Minnesota living with heart failure questionnaire for quality of life. There were no significant changes in parameters after the first treatment. However, after 3 months of treatment, there were significant improvements in the left ventricular ejection fraction, left ventricular posterior wall thickness, hemodynamics, exercise capacity, and quality of life. Additionally, ischemic burden and the number of ventricular premature beats also decreased slightly. Intermittent octreotide therapy led to significant improvements in patients with ischemic and idiopathic dilated cardiomyopathy refractory to conventional treatment. We believe that this therapy should be attempted as an adjunctive therapy in these patients, and that in this respect, randomized, double-blind, clinical, and large-scale studies are required before regular usage is undertaken.

Therapeutic effects of ghrelin on endotoxic shock in rats

We investigated the effects of ghrelin in a rat endotoxic shock model, and also observed the direct role of endotoxin on ghrelin generation in gastric mucosa. About 55% (11/20) of rats treated with lipopolysaccharide (5 mg/kg i.v.) alone died within 24 h of endotoxin injection. However, administration of ghrelin either at the same time as lipopolysaccharide injection (early treatment) or 12 h after lipopolysaccharide injection (late treatment) significantly decreased the mortality rate and ameliorated the hypotension seen in rats with endotoxic shock. Early and late treatment with ghrelin increased markedly the plasma glucose concentration and decreased the plasma lactate concentration. Early treatment with ghrelin attenuated significantly the deficiency in myocardial ATP content, but late treatment with ghrelin had no effect on myocardial ATP content. The plasma ghrelin level was significantly increased in the rats with endotoxin shock, and it increased further after ghrelin administration. Exposure of rat gastric mucosa in vitro to lipopolysaccharide (1.0 to 100 microg/ml) triggered the release of ghrelin from mucosa tissue in a dose- and time-dependent manner, meaning that lipopolysaccharide stimulated directly gastric mucosa to synthesize and secrete ghrelin. The results suggest that ghrelin could have therapeutic value for endotoxic shock.

Growth hormone therapy in heart failure: where are we now?

Despite improvement in survival with angiotensin-converting enzyme inhibitors and beta blockers, clinical events for patients with heart failure remain elevated. New therapies for heart failure are needed to improve functional capacity, quality of life, and prognosis. Growth hormone exerts direct and indirect effects on cardiac structure and function. Experimental models of heart failure and small studies have demonstrated significant improvements in cardiac function, hemodynamic parameters, functional capacity, and quality of life. Despite the lack of benefit demonstrated in small, short-term, randomized clinical trials, further studies are needed to assess the potential role of this adjuvant therapy in heart failure patients.

Preliminary observations on the effects of acute infusion of growth hormone on coronary vasculature and on myocardial function and energetics of an isolated and blood-perfused heart

Recent studies have shown that growth hormone (GH) deficiency may deteriorate post-ischemic myocardial reperfusion damage. Furthermore, GH has been reported to be a promising therapeutic option in the treatment of chronic myocardial dysfunction. However, the exact mechanisms of action of GH on the cardiovascular system, particularly in the acute setting, are still unclear. The aim of our study consisted of monitoring the acute effects of GH infusion on isolated blood-perfused rabbit heart according to dose-response pattern and during ischemic conditions to test its anti-ischemic property. Seven blood-donors perfused isolated hearts were used as experimental model. The mechanical and metabolic data of the isolated organs were continuously monitored. Under aerobic conditions, dose-response curves were initially tested after intracoronary infusion of GH at increasing dosages (1, 2, 3 mg/l). After a stabilization period, the effects of GH infusion (5 mg/kg) administered 30 minutes prior to acute global myocardial ischemia (30 minutes) were also investigated. At the doses tested, GH did not induce any changes either in the developed or in the diastolic pressures of the isolated organ. However, transient reduction of the coronary perfusion pressure was observed at the dosage of 3 mg/l. During the ischemia/reperfusion study, at the dosages used in this study, GH did not modify either the degree of stunning in the early reperfusion or the recovery of the developed pressure at the end of reperfusion. In addition, GH did not prevent either the increase of diastolic pressure during ischemia or the release of lactate and CPK during reperfusion. Tissue content of high-energy phosphates was also not changed by GH infusion. In our experimental model, acute GH infusion did not reduce the ischemic/reperfusion damage of the myocardium. However, GH transiently induced coronary vasodilation without modifying the myocardial contractility. Acute effects of GH appear, therefore, to predominantly relate to vascular dilation suggesting that the effects on myocardial contractility may require long-lasting intake being likely linked to enhancement of specific protein synthesis or gene expression of cardiac myocytes.

Effects of early treatment with growth hormone on infarct size, survival, and cardiac gene expression after acute myocardial infarction

OBJECTIVE

This study examined the effects of growth hormone (GH) on infarct size, survival, and cardiac gene expression in rats with acute myocardial infarction.

DESIGN

Animals randomly received sc injection of either saline vehicle (n = 98) or GH (2mg/kg/day, n = 105) for 14 days commencing the day of left coronary artery ligation. Infarct size was determined by morphometric analysis at the time of death or at 52 weeks post-surgery. Gene expression was analyzed by real-time RT-PCR after 2-week treatment.

RESULTS

GH decreased infarct size by 18% (P < 0.01) and increased survival by 36% at 52 weeks. GH also significantly reduced cardiac expression of atrial natriuretic factor, beta-myosin heavy chain, alpha-smooth muscle actin, collagen I, collagen III, fibronectin, and pro-inflammatory cytokines.

CONCLUSIONS

Treatment with GH for 2 weeks beginning on the day of myocardial infarction produced beneficial effects that were associated with reductions in cardiac gene expression symptomatic of pathological remodeling.

Effects of acute hexarelin administration on cardiac performance in patients with coronary artery disease during by-pass surgery

Growth hormone (GH) secretagogues are synthetic molecules with neuroendocrine but also cardiovascular activities mediated by specific GH secretagogue-receptors. The acute administration of hexarelin, a peptidyl GH secretagogue, increases left ventricular ejection fraction in normal subjects and even in patients with severe GH deficiency. We evaluated cardiac performances in patients with coronary artery disease after acute administration of hexarelin (2.0 microg/kg, i.v.) compared to that in patients given with GH-releasing hormone (GHRH; 2.0 microg/kg, i.v.), recombinant human (rh)-GH (10.0 microg/kg, i.v.) or placebo. Cardiac performance was studied in 24 male patients (age [mean +/- S.E.M.]: 59.5 +/- 1.1 years; body mass index: 24.6 +/- 0.9 kg/m(2); left ventricular ejection fraction: 57.2 +/- 1.4%) with coronary artery disease undergoing by-pass surgery during general anesthesia. Left ventricular ejection fraction, left ventricular end diastolic volume, cardiac index and cardiac output were evaluated by intraoperative omniplane transoesophageal echocardiography while wedge pressure, central venous pressure, mean arterial pressure and systemic vascular resistance index were evaluated by systemic and pulmonary arterial catheterization. RhGH, GHRH and placebo did not exert any hemodynamic effect while hexarelin induced a prompt (after +10 min) increase in left ventricular ejection fraction (P < 0.001), cardiac index (P < 0.001) and cardiac output (P < 0.001) lasting up to +90 min without any variation in left ventricular end diastolic volume. Accordingly, hexarelin induced a reduction of wedge pressure (P < 0.01). These changes occurred in the presence of increased mean arterial pressure (P < 0.05) and transient decrease of central venous pressure (P < 0.05 at +30 min only) but no change in systemic vascular resistance index. Heart rate after hexarelin was similar to that after placebo. Hexarelin induced a slight increase in GH levels which was similar to that after GHRH but far lower (P < 0.01) than that after rhGH. Thus, in patients with coronary artery disease undergoing by-pass surgery, the acute administration of hexarelin clearly improves cardiac performance without any relevant variation in systemic vascular resistance. The cardiotropic effect of hexarelin is not shared by GHRH or by rhGH, indicating that it is not mediated by the increase in circulating GH levels but more likely reflects activation of specific cardiovascular GH secretagogue receptors.

Therapeutic potential of implanted tissue-engineered bioartificial muscles delivering recombinant proteins to the sheep heart

Tissue-engineered primary adult sheep muscle cells genetically engineered to express either rhVEGF or rhIGF-1 secreted the bioactive proteins locally in the sheep heart for at least 30 days.

Acquired growth hormone resistance in patients with chronic heart failure: implications for therapy with growth hormone

OBJECTIVES

We aimed to determine whether growth hormone (GH) resistance is present in patients with chronic heart failure (CHF) and whether it may be linked to the biochemical response to GH treatment.

BACKGROUND

Acquired GH resistance is a feature of severe illness, in particular, cachexia. In patients with CHF, the response to GH therapy appears to be variable.

METHODS

Biochemical markers of the GH-insulin-like growth factor-I (IGF-I) axis were compared in 21 cachectic patients with CHF, 51 noncachectic patients and 26 healthy control subjects. In separate studies, the predictive value of baseline biochemical variables for the IGF-I response to GH treatment was analyzed.

RESULTS

Cachectic patients showed an increase of total GH and immunologically intact GH (p < or = 0.0002) and a decrease of GH-binding protein (BP) (p = 0.005), IGF-BP3 (p = 0.01) and IGF-I (p = 0.06), compared with noncachectic patients. Similar changes were found when the cachectic group was compared with the control group. No differences were found between noncachectic patients and control subjects. Levels of GH-BP correlated with the IGF-I/GH ratio in all subgroups (all p < or = 0.002). Baseline GH-BP levels were related to the increase of IGF-I levels in response to GH treatment in patients with CHF after 24 h (r = 0.83, p = 0.005; n = 9; study 2), 44 days (r = 0.52, p = 0.007; n = 25; study 3) and 96 days (r = 0.54, p = 0.006; n = 24; study 3).

CONCLUSIONS

Most cachectic and some noncachectic patients with CHF show features of acquired GH resistance. The principal predictors of the biochemical features of GH resistance and of the poor biochemical response to short-term and longer-term GH treatment are GH-BP plasma levels. The presence of GH resistance is potentially a major factor determining the response to GH therapy in patients with CHF.

[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.

Role of growth hormone in chronic heart failure. Therapeutic implications

Congestive heart failure is a multiple aetiology, high prevalence, poor prognosis cardiovascular disorder. Medical treatment of dilated cardiomyopathy is aimed at alleviating the symptoms of heart failure. Diuretics, ACE inhibitors and very recently, beta-blockers have been shown to have favourable effects on symptoms, exercise capacity and mortality. Growth hormone (GH) and insulin-like growth factor (IGF)-1 are involved in several physiological processes such as the control of muscle mass and function, body composition and regulation of nutrient metabolism. The roles of GH and IGF-1 as modulators of myocardial structure and function are well established. Receptors for both GH and IGF-1 are expressed by cardiac myocytes; therefore, GH may act directly on the heart or via the induction of local or systemic IGF-1, whereas IGF-1 may act by endocrine, paracrine or autocrine mechanisms. Patients with acromegaly have an increased propensity to develop ventricular hypertrophy and cardiovascular diseases and, in addition, an impaired cardiac efficiency is observed in patients with GH deficiency. Animal models of pressure and volume overload have demonstrated up-regulation of cardiac IGF-1 production and expression of GH and IGF-1 receptors, implying that the local regulation of these factors is influenced by haemodynamic changes. Moreover, experimental studies suggest that GH and IGF-1 have stimulatory effects on myocardial contractility, possibly mediated by changes in intracellular calcium handling. Heart failure is caused by ventricular dilatation with abnormal wall thickening, which leads to impaired cardiac performance; therefore, based on the evidence available for GH we would expect beneficial effects from the use of GH in these patients. Several papers highlight the positive influence of GH in the regulation of heart development and performance. In patients with GH deficiency, GH administration dramatically improves cardiac function. In small nonblind studies, both short and long term GH treatment have demonstrated beneficial effects in patients with heart failure secondary to ischaemic or idiophatic cardiomyopathy. Recently, two randomised, placebo-controlled studies, did not show significant GH-mediated improvement in cardiac performance in patients with dilated cardiomyopathy, despite significant increases in IGF-1. Acquired GH resistance, might be an important feature of severe heart failure and explain the different responses to GH therapy seen in different patients. Whether GH treatment will finally find a place, and with which modalities, in the treatment of heart failure remains to be established.

Growth hormone: a promising treatment for the failing heart?

Many pathologic processes that accelerate the progression of heart failure, such as cardiac remodeling and impaired contractility, may be modulated by administration of recombinant growth hormone. The agent improves structural and functional aspects of the failing heart both in the short term and after several months of therapy. However, conflicting clinical results cast doubt on whether it has a clear benefit in all of these patients. In addition, growth hormone therapy may be associated with cardiac and noncardiac adverse effects. Many questions must be addressed before its place in heart failure therapy is established. Optimal patient population, dosing regimen, duration of therapy, and effect on patient survival are unknown. Until larger, blinded studies are completed, growth hormone therapy remains an investigational approach to managing refractory heart failure.

Exercise-induced microalbuminuria in patients with active acromegaly: acute effects of slow-release lanreotide, a long-acting somatostatin analog

Recent clinical studies have demonstrated an increase of urinary albumin excretion (UAE) at rest in acromegalic patients and, on the other hand, a reduced UAE in patients with growth hormone (GH) deficiency. Physical exercise is known to induce abnormal UAE in patients with diabetes, probably unmasking early glomerular alterations. The effect of exercise on UAE in acromegaly is not known. Moreover, the effect of acute but sustained GH inhibition in acromegaly on UAE at rest and after exercise has never been studied. The aim of our study was to evaluate the acute short-term effects of slow-release lanreotide (SR-L), a long-acting somatostatin analog, on UAE and alpha1-microglobulinuria (A-1-M), a marker of renal tubular damage, at rest and after exercise in 7 normotensive patients with active acromegaly and normal renal function (4 males and 3 females; mean age, 53 +/- 3.1 years; body mass index [BMI], 27.3 +/- 1.1 kg/m2) at baseline and 7 and 14 days after SR-L injection (30 mg). Two of the acromegalic patients were microalbuminuric at rest, and in other 3 cases, UAE was in the borderline range (10 to 20 microg/min). At baseline in the acromegalic subjects, we found a significant increase in UAE at rest with respect to 7 normal subjects considered as a control group. GH and insulin-like growth factor-1 (IGF-1) were also reduced compared with baseline 7 and 14 days after SR-L injection (GH, 13.4 +/- 7.3 and 13.61 +/- 7 v 18.5 +/- 9.3 microg/L, P < .05; IGF-1, 230 +/- 53 and 255 +/- 54 v 275 +/- 64 microg/L). Concomitantly, we observed a significant decrease of UAE at rest and after exercise and 7 and 14 days after SR-L injection as compared with baseline values (27.3 +/- 20.5 and 18.2 +/- 13.7 v 35.3 +/- 12.8 microg/min, P < .05; exercise, 48.5 +/- 24.1 and 18.6 +/- 6.8 v68.3 +/- 39.7 microg/min, P < .05). A-1-M always remained in the normal range (< 12 mg/L) both at rest and after exercise. We can thus conclude that in acromegaly, submaximal exercise induces abnormal increases in microalbuminuria. We hypothesize that this phenomenon may be due to the functional glomeruler involvement. SR-L can significantly reduce UAE at rest and after exercise in the short-term in acromegaly, probably via a decrease in circulating GH levels.

The severity of chronic heart failure due to coronary artery disease predicts the endocrine effects of short-term growth hormone administration

Treatment with human recombinant GH has yielded conflicting results in patients with heart failure. As GH sensitivity may be important for treatment effects, the present study evaluated GH secretion and sensitivity in noncachectic patients with ischemic heart failure. Twenty clinically stable, male patients with moderate heart failure (mean New York Heart Association class, 2.0 +/- 0.8; mean ejection fraction, 30.0 +/- 8.4%) due to coronary artery disease were randomly assigned single blind to a low dose (group A; n = 10) and a high dose (group B; n = 10) group, receiving either 5 microg/kg x day recombinant human GH for 4 days followed by 10 microg/kg x day GH for another 4 days or 10 and 20 microg/kg x day GH, respectively. Cardiac function was assessed by echocardiography. Serum insulin-like growth factor I (IGF-I), IGF-binding protein-3 (IGFBP-3), and 24-h urinary GH excretion as a measure of pituitary GH secretion were determined at baseline and on days 5 and 9. Baseline IGF-I and IGFBP-3 levels and GH excretion were significantly diminished compared to those in age-matched controls. There was a dose-dependent increase in IGF-I and IGFBP-3 during GH treatment. The increase in IGF-I induced by 10 microg/kg x day GH correlated positively to left ventricular ejection fraction (r = 0.59; P = 0.006) and inversely to left ventricular end-diastolic and end-systolic dimensions (r < -0.6 and P < 0.01 for both). In conclusion, GH secretion and serum levels of IGF-I and IGFBP-3 are diminished in patients with moderate ischemic heart failure. Left ventricular function determines the sensitivity of the GH/IGF-I system, measured as the IGF-I response to GH application. This finding suggests that individual dose adjustments may be an indispensable prerequisite for successful GH therapy in heart failure.