The influence of growth hormone therapy on ultrasound myocardial tissue characterization in patients with childhood onset GH deficiency
Introduction
There is accumulating evidence that GH has an important role in the maintenance of normal cardiac growth and function [1]. Both GH and insulin-like growth factor I (IGF-I) receptors are expressed in the myocardium [2], and it has been demonstrated that IGF-I stimulates myofibril development [3] and increases isometric force [4]. GHD onset in a period of somatic maturation has more profound effects on organ development than GHD starting later in life [5]. Appropriate therapy with GH has previously been discontinued at the end of linear growth, although somatic growth is unlikely to be completed at this time. Numerous studies have reported on cardiac function in GHD, with variable results [6], [7], [8], [9]. Abnormalities in left ventricular diastolic function, both at rest and in response to exercise [6], [7], have been determined either echocardiographically [7] or by radionuclide angiography [6]. Impairment in systolic function has similarly been reported, typically with increased end-systolic wall stress, reduced ventricular posterior wall thickness, reduced cardiac output (CO) and cardiac index, and lower ejection fraction and fractional shortening than controls [8], [9]. Abnormalities have been found regardless of the patients' age and age of onset of their GHD [6], [7]. A detailed analysis of 55 adulthood onset GHD patients and 36 controls [6] showed that 24% of the GHD patients but none of the controls had impaired ejection fraction at rest and that the ejection fraction change during exercise was abnormal in 65% of the GHD patients. The effects of GH replacement have also been studied with evidence for improvement in ejection fraction, fractional shortening, stroke volume, and CO, but rarely with any structural changes of the heart [8], [9], [10], [11], [12].
The integrated ultrasonic backscatter (IBS) technique is a useful noninvasive method for measuring acoustic properties of the tissue. Several recent experimental and clinical studies have suggested that IBS signals are affected by myocardial structural features [13]. The clinical utility or usefulness of ultrasonic myocardial tissue characterization using IBS has been shown in a variety of conditions such as the aging heart [14], dilated cardiomyopathy [15], hypertrophic cardiomyopathy [16], [17], myocardial ischemia [18], [19], [20], diabetes mellitus [21], cardiac allograft rejection [22], and cardiac amyloidosis [23]. In this study, we investigated the effects of GH replacement in patients with childhood onset GHD on cardiac structure and functional indices measured by echocardiographic techniques including acoustic quantification with cyclic variation (CV) of integrated backscatter from the myocardium during the cardiac cycle.
Section snippets
Study group
Sixteen patients (10 males, mean age 42.3±13.1 years, range 18–60) with childhood onset GHD were included in the study. Three patients had received GH for short stature in the past but were off therapy for several years, whereas 13 patients had never been treated with GH. GHD was confirmed before the start of the study by a serum IGF-I concentration: 28.0–63.0 ng/ml (mean 43.4±7.8 ng/ml) and a maximal GH response to insulin-induced hypoglycemia of less than 3 μg/l in all subjects. All patients
Results
In all 16 patients the supine arterial blood pressure, measured by a standard mercury sphygmomanometer, did not differ at the end of the study (117.1±15.4/78.6±11.1 mm Hg) from baseline (116.9±18.5/78.2±9.1 mm Hg). Heart rate did not change after 12 months of GH treatment (73.0±8.6 vs. 76.8±8.4 beats/min, p=0.055).
Echocardiographic data were able to be evaluated in all 16 subjects. During the study, left atrial end-systolic diameter and left ventricular end-diastolic diameter did not change
Discussion
Epidemiological data suggest that adults with hypopituitarism have reduced life expectancy compared with that of healthy controls, with a greater than twofold increase in mortality from cardiovascular disease [27]. The mechanisms responsible for the increased cardiovascular mortality remain largely unknown, but carotid artery ultrasonography has demonstrated increased intima-medial thickening and intimal plaque formation [28] and reduced arterial compliance [29] in hypopituitary adults. The
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Effect of Growth Hormone on Cardiac Contractility in Patients With Adult Onset Growth Hormone Deficiency
2007, American Journal of CardiologyCitation Excerpt :We have also evaluated myocardial structural change after GH replacement using tissue characterization. It has been reported that GH replacement in adults with childhood-onset GH deficiency results in improvements in cardiac structure assessed by tissue characterization.21 This result contrasts with our study, in which calibrated IB in GH deficiency did not change after GH replacement.
Growth hormone therapy and the heart
2006, American Journal of CardiologyCitation Excerpt :This is in contrast to the results of Colao et al,3 who studied 15 GH-deficient patients and found significant increases in LV mass index, the LV ejection fraction at peak exercise (but not at rest), and exercise duration after 12 months of treatment. More recently, Minczykowski et al26 found that LV diameter and wall thickness did not change after 12 months of GH treatment in 16 adult patients with COGHD. These discrepancies in the effects of GH therapy on LV mass may be related to the highly variable degree of basal LV mass impairment.
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