Cardiovascular effects of gastric intubation and distension in healthy humans.

Few data exist on the effect of upper gut stimuli on the cardiovascular system. Aim of our study was to evaluate the cardiovascular effects of gastric intubation and distension. Eleven healthy subjects (eight men, aged 21-30 years) were studied and a non-invasive beat-to-beat cardiovascular monitoring system was used. After 15-min basal recording, a bag catheter was positioned in the proximal stomach and connected to a barostat. Recordings were first performed for 15 min with the bag deflated, then during inflation of air using a 100 mL per 2 min stepwise protocol until epigastric discomfort was reported, and finally for 15 min with the bag inflated at 75% of discomfort volume spared from the preceding period by 10 min with the bag deflated. Presence of the deflated bag catheter significantly increased mean arterial pressure. Stepwise distension progressively increased heart rate and cardiac index, while mean arterial pressure was affected only at discomfort volume. Peripheral resistances and systemic plasma catecholamines were unaffected. During prolonged distension, the effect on heart rate and cardiac index was transient. In conclusion, both gastric intubation and distension alter cardiovascular parameters, but the effect of distension undergoes rapid adaptation. Experimentally induced gastric distension is a valuable stimulus to study viscero-cardiovascular reflexes and their mechanisms using beat-to-beat measurements.

Evaluation of cardiac structure by echoreflectivity analysis in acromegaly: effects of treatment.

OBJECTIVES: Cardiac echoreflectivity is a noninvasive tool for evaluating cardiac fibrosis. The present paper aimed to study the modifications of cardiac echoreflectivity in a group of acromegalic patients before and after therapy, and to assess possible correlations with serum levels of procollagen III (PIIINP), a peripheral index of collagen synthesis. DESIGN AND METHODS: Cardiac echoreflectivity (as assessed by analyzing 2-D echocardiograms digitized off-line onto a personal computer) and PIIINP levels were evaluated in 16 acromegalic patients of new diagnosis not affected by arterial hypertension (10 males, six females, age+/-s.d.: 38+/-10 years), and in a group of 16 sex- and age-matched healthy subjects. All the patients were re-evaluated after surgical and/or medical therapy for acromegaly. The echo patterns were analyzed by software that supplies the derived collagen volume fraction (dCVF), an index of fibrosis. RESULTS: At baseline, acromegalic patients showed significantly higher dCVF values and PIIINP levels than healthy controls (3.1+/-0.5% vs 1.6+/-0.3%, P<0.01 and 8.7+/-2.2 vs 3.1+/-1.1 ng/ml, P<0.05, respectively, by unpaired Student's t-test). After therapy, dCVF and PIIINP levels normalized in the six controlled patients (that is, GH of <2.5 microg/l and IGF-I within normal range) (dCVF from 2.8+/-0.4% to 1.4+/-0.2%, P<0.001; PIIINP from 8+/-2.7 to 3.3+/-1.9 ng/ml, P<0.05), while no significant changes were found in noncontrolled patients (dCVF from 3.3+/-0.6% to 2.9+/-1.2% and PIIINP from 9.1+/-1.9 to 7.9+/-3.5 ng/ml, P=NS). A positive correlation between dCVF and PIIINP (r=0.75, P<0.001) and between IGF-I and both dCVF and PIIINP (r=0.65 and 0.61 respectively, P<0.05) was found in acromegalic patients. CONCLUSIONS: Cardiac echoreflectivity, which may be a reflection of heart collagen content, is increased in patients with active acromegaly and correlates with PIIINP concentrations. After cure or adequate control of the disease, both parameters revert to normal. Echoreflectivity analysis could be a useful adjuvant parameter in the assessment of the activity of acromegalic disease.

Effects of thyroid hormones on cardiac structure: a tissue characterization study in patients with thyroid disorders before and after treatment.

Experimental evidence suggests an involvement of thyroid hormones in myocardial nonmyocyte component growth. We evaluated the possible role of thyroid hormones in myocardial remodeling by ultrasonic tissue characterization (videodensitometry) in 8 hyperthyroid patients, in 10 hypothyroid patients, and in 2 patients with thyroid hormone resistance syndrome (RTH), before, 60, and 120 days after treatment (T0, T60, T120), and in 10 age-matched euthyroids. According to a previously described procedure, the derived collagen volume fraction (dCVF%, an echocardiographic index estimating the collagen content) was predicted from the pixel-level frequency distribution width (broadband, Bb) of the selected echocardiographic images. Thyrotropin (TSH), free thyroxine (FT4), and free triiodothyronine (FT3) were assessed by immunometric method. QT interval dispersion (QTd) on basal electrocardiogram was measured as a marker of dyshomogeneous ventricular repolarization. At T0, Bb and dCVF% were normal in hyperthyroid and euthyroid patients, and slightly increased in RTH patients, whereas significantly higher values were found in hypothyroids. At T60, a significant reduction in Bb was observed in hypothyroids, with nearly normal dCVF% values. This trend was confirmed at T120 with complete normalization of echoreflectivity. No echoreflectivity changes were observed in hyperthyroid and RTH patients during treatment. QTd was significantly increased in hypothyroids at T0, while no significant differences were found among groups at T60 and T120. Because the different videodeonsitometric myocardial properties observed in hypothyroid versus hyperthyroid patients correspond to an increase of dCVF%, this study suggests that thyroid hormones exert an inhibitory effect on myocardial collagen synthesis in humans.

Non-motor effects of deep brain stimulation of the subthalamic nucleus in Parkinson's disease: preliminary physiological results.

Although deep brain stimulation (DBS) is a clinically effective therapy for patients with advanced Parkinson's disease (PD), its physiological effects on the brain and possible actions on non-motor functional systems remain largely unknown. This study evaluated the effects of DBS of the subthalamic nucleus (STN) on neurophysiological variables and on cardiovascular physiology. Nine patients affected by PD undergoing chronic DBS of the STN have been studied. We performed electroencephalography (EEG), somatosensory (SEPs) and visual evoked potentials (VEPs), exteroceptive masseteric silent period and sympathetic skin response (SSR) studies with DBS ON and OFF. To assess the effects of stimulation on the cardiovascular system the tilt test and plasma renin activity were studied. When we turned the DBS OFF, both SEP N20 and the VEP P100 component increased significantly in amplitude whereas the SSR decreased in amplitude and increased in latency. Although plasma renin activity tended to increase with DBS OFF, its modification induced by postural changes and blood pressure values did not significantly differ with DBS ON and OFF. We conclude that DBS of the STN in PD, besides inducing a clinical improvement, induces several non-motor effects.

Vascular network changes in the retina during ageing in normal subjects: a computerized quantitative analysis.

BACKGROUND: Direct ophthalmoscopic examination of fundus oculi is widely used for the qualitative evaluation of target organ damage in several pathological conditions. At present, there are no reliable techniques available to quantify retinal vascular damage. The aim of this study was to develop a computerized technique for the quantitative analysis of fundus oculi. METHODS: We studied 68 non-smoking, normotensive normal subjects, with a visual acuity > 8/10. From each subject retinal images were taken using a non-mydriatic ophthalmoscope and digitized onto a personal computer. In each image the area of analysis was set to a circular selection, corresponding to 25% of the whole fundus oculi, concentric with the optic disc. From each selection arterial and venous area and mean arteriolar bifurcation angle were obtained. Measurements were taken in a blinded way by two operators and, by the same operator, twice at different times. Parameters were correlated with age and body surface area. RESULTS: Retinal arterial density (arteries 7.44 +/- 1.25%; bifurcation angle 75 +/- 16 degrees) was significantly correlated with age, but not with body surface area. Intra- and interobserver coefficient of variation resulted 2.5 and 3.2%, respectively. CONCLUSIONS: Computerized analysis of the fundus oculi with the evaluation of vascular density indexes represents a simple and reproducible technique that could be useful in identifying changes in retinal vascular network during ageing.

Blood pressure-independent cardiac hypertrophy in acromegalic patients.

OBJECTIVE: Acromegaly is frequently associated with an increase in left ventricular mass, even in the absence of systemic hypertension. Pathological studies on acromegalic hearts have shown an extensive interstitial fibrosis, suggesting the existence of a specific acromegalic cardiomyopathy. The aim of this study was to assess left ventricular wall structure in acromegaly by ultrasonic tissue characterization. DESIGN AND METHODS: We studied 10 untreated acromegalic patients and 10 age-matched healthy control subjects. The echo patterns of two-dimensional long-axis end-diastolic echocardiograms were assessed by colour-scale analysis of the interventricular septum, with estimates of the mean colour scale value, the broad band (Bb) and the derived collagen volume fraction (dCVF). We also measured electrocardiographic QT interval dispersion (QTd) as a marker of dyshomogeneous ventricular repolarization. RESULTS: Seven patients had left ventricular hypertrophy according to the sex-independent criteria; of these, two had arterial hypertension. None of our patients had echocardiographic evidence of diastolic or systolic dysfunction. All patients showed significantly increased myocardial echoreflectivity (Bb = 106.4+/-12.1 versus 79.3+/-6.5; dCVF% = 2.78+/-0.53 versus 1.58+/-0.29; P < 0.0001) and QTd (66+/-13 ms versus 54+/-8 ms, P < 0.05). A significant correlation was found between dCVF and the duration of acromegaly (r = 0.80; P = 0.005). CONCLUSIONS: Left ventricular remodelling observed in acromegaly is not related to the presence of arterial hypertension; we hypothesize that the increased echoreflectivity and QTd are long-term consequences of cardiac hypertrophy and prolonged exposure to high levels of growth hormone and insulin-like growth factor-I.