G Cini

Thyroid hormones and the cardiovascular system: Pathophysiology and interventions

Thyroid dysfunction, however mild, can significantly affect the cardiovascular (CV) system. The effects of thyroid hormones may be viewed as genomic and non-genomic, with the former occurring over a longer time scale and both affecting structural and functional proteins in CV tissue. As the interplay between thyroid function and the CV system becomes elucidated, particularly in the context of a system biology approach, the heart failure phenotype is better understood. Symptomatology is related to disturbance in inotropic and chronotropic function. Moreover, biochemical changes reflected by thyroid function testing with the non-thyroidal illness syndrome can prognosticate and guide therapy in heart failure. In addition, empiric treatment with thyroid hormone analogues or T3 represent emergent and highly controversial interventions.

Asymmetric septal hypertrophy and sympathetic overactivity in normotensive hemodialyzed patients

Sympathetic activity has been evaluated in 23 chronic uremic normotensive patients on long-term hemodialysis. M-mode and bidimensional echocardiographic finding of asymmetric septal hypertrophy (ASH) was shown in seven (30.4%). Sympathetic function was assessed by determining arterial plasma norepinephrine (plasma NE) and epinephrine (plasma E) in supine and upright positions, both before and after dialysis. After dialysis standing caused a significant increase in plasma NE levels in the patients with ASH in comparison to the patients without ASH and the control group. A significant decrease in mean blood pressure (mBP) and a sharp heart rate (HR) increase were detected in the patients without ASH, whereas mBP and HR were unchanged in the patients with ASH. Predialysis serum creatinine and fasting triglycerides were found to be significantly higher in the group with ASH. These results suggest that sympathetic overactivity may play a role in the development of interventricular septum hypertrophy. This increased neurosympathetic responsiveness is probably related to the counteraction of the postural dialysis-induced hypotension.

Asymmetric septal hypertrophy in uremic-normotensive patients on regular hemodialysis. An M-mode and two-dimensional echocardiographic study.

We have observed a high incidence (36.4%) of asymmetric septal hypertrophy (ASH), detected with the use of M-mode (MME) and two-dimensional echocardiography (2DE), in normotensive patients with chronic renal failure on maintenance hemodialysis without signs of cardiac diseases. ASH was detected by conventional MME in 11 cases and was confirmed with the use of 2DE in 8 cases showing a diagnostic concordance of 72.7% between the two methods. After dialysis the MME study of the left ventricular (LV) performance showed an evident impairment of cardiac index (CI) due to reduction of LV volume in addition to an abnormality of septal function. The presence of ASH does not impair the percentage of fractional shortening (FS%), the mean circumferential shortening (mean Vcf) and the ejection fraction (EF%), probably because of a compensatory performance of the LV posterior wall. Predialysis serum creatinine and fasting triglycerides have been found significantly higher in the group with ASH. ASH may be considered as a focal and early form of myocardial involvement in uremic patients on regular hemodialytic treatment.

Echocardiographic hemodynamic study during ultrafiltration sequential dialysis.

4 patients on regular dialysis were studied by the echocardiographic method during ultrafiltration and dialysis performed sequentially according to two different protocols. Blood pressure, heart rate, cardiac output, stroke volume, systolic and diastolic dimension of the left ventricle, systolic and diastolic volumes of the left ventricle, ejection fraction, shortening fraction and total peripheral vascular resistance index were measured. During ultrafiltration there is an increase of the total peripheral vascular resistance index. Myocardial contractility improves only during dialysis. Physiopathologic implications are discussed.

Changes in autonomic regulation and ventricular repolarization induced by subclinical hyperthyroidism

UNLABELLED The aim of the present study was to evaluate the effect of subclinical hyperthyroidism (SHT) on cardiovascular autonomic function and ventricular repolarization. METHODS Thirty subjects (25 females; mean age 49.6 ± 9.8 years) with SHT, as judged by reduced TSH serum levels and normal free T4 and T3 serum levels, and 30 age and sex-matched control subjects underwent standard 12-lead ECG, and 24h ambulatory ECG monitoring. The dispersion of the QT interval, an index of inhomogeneity of repolarization, and the heart rate variability (HRV), a measure of cardiac autonomic modulation, were studied. RESULTS Patients with SHT showed higher QT dispersion (p<0.001) and lower HRV measures (0.01>p<0.001) than controls. In SHT patients, QT dispersion was inversely related to HRV (r=-0.47, p<0.01). CONCLUSION The results of the present study demonstrated that SHT is associated with a sympathovagal imbalance, characterized by increased sympathetic activity in the presence of diminished vagal tone, and with an increased inhomogeneity of ventricular recovery times. The assessment of HRV and QT dispersion in patients with SHT may represent a useful tool in monitoring the cardiovascular risk of this condition.

Acute respiratory distress syndrome in an adult patient with a myelodysplastic disorder.

A 58-year-old man was diagnosed to have refractory anaemia with excessive blasts. After 3 1/2 years of relative control on periodic blood transfusions, the patient developed an acute leukaemia. Although the blastic crisis was not extreme (WBC counts less than 100 X 10(9)/l), a severe, intractable respiratory distress syndrome set in and brought the patient to the exitus in a few days. Overt signs of septic shock were absent, as was evidence of any other known cause of adult respiratory distress. Acute pulmonary failure can be the cause of death in leukaemic patients even in the absence of overwhelming sepsis or hyperleucocytosis.

Subclinical hyperthyroidism and cardiovascular manifestations: a reevaluation of the association

Subclinical hyperthyroidism (SH) has been reported associated with atrial fibrillation (AF), heart failure (HF) and coronary heart disease events, including mortality. An expert opinion indicates that AF is the possible link between SH and the other important cardiovascular (CV) manifestations. We analyzed the data of three recent studies including 60,883 subjects of whom 2,284 SH patients. In these subjects, the ratio between the AF events and each of the other above reported CV events varied from 0.14 to 0.4 in SH and from 0.2 to 2.4 in euthyroidism (ET). The general pattern of this ratio in 6 comparisons performed was not significantly higher for SH than ET. This data suggest that AF is not the major link between SH and the related CV manifestations. We suggest that a further link to be considered is the higher frequency of the early atherosclerosis manifestations such as carotid intima media thickness or carotid integrated back scatter, observed in SH. This atherogenic effect of SH can affect the occurrence of all the above clinical CV manifestations.

Dilation of venous vessels at the splenic hilum in normal sized spleens as an indication of pathologic splenic involvement : preliminary results

Twelve hundred patients without liver or heart disease, having a normal sized spleen without focal lesions, were examined by ultrasonography to measure the inner diameter of the splenic vein in relation to possible current or recent recovery from pathologic processes. SVD was measured at the hilum of the spleen with the patients supine. Ten of the patients in whom dilation of the SVD was found, together with a group of healthy controls (25), were subsequently studied with a duplex Doppler analysis to measure the venous outflow from the spleen. The results showed 1,175 spleens (98%) with SVD at the hilum of < 8 mm and 25 spleens (2%) with SVD of > 8 mm. Twenty‐three of 25 patients (92%) with enlarged SVD had recent histories of hematopoietic or infectious diseases. Ten of 23 patients with enlarged SVD were studied further with a Doppler analysis. They demonstrated a rapid splenic blood flow with maximum flow velocities ranging from 14 to 27 cm/sec and high outflow volumes (from 430 to 1,227 ml/min, averaging 786 ml/min +/‐ 266), both significantly increased in comparison with controls (outflow volume from 200 to 355 ml/min, averaging 274 +/‐ 40; P < 0.0001). We conclude that dilation of the SVD accompanied by an increased intrasplenic blood flow volume without splenic enlargement would indicate a state of increased perfusion of splenic tissue associated with an immune response, reflecting reaction of the spleen to disease.