The effect of levothyroxine treatment on left ventricular function in subclinical hypothyroidism

ABSTRACT Objective: Treatment of subclinical hypothyroidism (ScH), especially the mild form of ScH, is controversial because thyroid hormones influence cardiac function. We investigate left ventricular systolic and diastolic function in ScH and evaluate the effect of 5-month levothyroxine treatment. Subjects and methods: Fifty-four patients with newly diagnosed mild ScH (4.2 <TSH < 10.0 mU/L) and 30 euthyroid subjects matched by age were analysed. Laboratory analyses and an echocardiography study were done at the first visit and after 5 months in euthyroid stage in patients with ScH. Results: Compared to healthy controls, patients with ScH had a lower E/A ratio (1.03 ± 0.29 vs. 1.26 ± 0.36, p < 0.01), higher E/e' sep. ratio (762 ± 2.29 vs. 6.04 ± 1.64, p < 0.01), higher myocardial performance index (MPI) (0.47 ± 0.08 vs. 0.43 ± 0.07, p < 0.05), lower global longitudinal strain (GLS) (-19.5 ± 2.3 vs. −20.9 ± 1.7%, p < 0.05), and lower S wave derived by tissue Doppler imaging (0.077 ± 0.013 vs. 0.092 ± 0.011 m/s, p < 0.01). Levothyroxine treatment in patients with ScH contributed to higher EF (62.9 ± 3.9 vs. 61.6 ± 4.4%, p < 0.05), lower E/e' sep. ratio (6.60 ± 2.06 vs. 762 ± 2.29, p < 0.01), lower MPI (0.43 ± 0.07 vs. 0.47 ± 0.08%, p < 0.01), and improved GLS (-20.07 ± 2.7 vs. −19.55 ± 2.3%, p < 0.05) compared to values in ScH patients at baseline. Furthermore, in all study populations (ScH patients before and after levothyroxine therapy and controls), TSH levels significantly negatively correlated with EF (r = −0.15, p < 0.05), E/A (r = −0.14, p < 0.05), GLS (r = −0.26, p < 0.001), and S/TDI (r = −0.22, p < 0.01) and positively correlated with E/e' sep. (r = 0.14, p < 0.05). Conclusion: Patients with subclinical hypothyroidism versus healthy individuals had subtle changes in certain parameters that indicate involvement of systolic and diastolic function of the left ventricle. Although the values of the parameters were in normal range, they were significantly different compared to ScH and the control group at baseline, as well as to the ScH groups before and after treatment.The results of our study suggest that patients with ScH must be followed up during treatment to assess improvement of the disease. Some of the echocardiography obtained parameters were reversible after levothyroxine therapy.

Effect of different anesthetic agents on left ventricular systolic function assessed by echocardiography in hamsters

Determination of left ventricular ejection fraction (LVEF) using in vivo imaging is the cardiac functional parameter most frequently employed in preclinical research. However, there is considerable conflict regarding the effects of anesthetic agents on LVEF. This study aimed at assessing the effects of various anesthetic agents on LVEF in hamsters using transthoracic echocardiography. Twelve female hamsters were submitted to echocardiography imaging separated by 1-week intervals under the following conditions: 1) conscious animals, 2) animals anesthetized with isoflurane (inhaled ISO, 3 L/min), 3) animals anesthetized with thiopental (TP, 50 mg/kg, intraperitoneal), and 4) animals anesthetized with 100 mg/kg ketamine plus 10 mg/kg xylazine injected intramuscularly (K/X). LVEF obtained under the effect of anesthetics (ISO=62.2±3.1%, TP=66.2±2.7% and K/X=75.8±1.6%) was significantly lower than that obtained in conscious animals (87.5±1.7%, P<0.0001). The K/X combination elicited significantly higher LVEF values compared to ISO (P<0.001) and TP (P<0.05). K/X was associated with a lower dispersion of individual LVEF values compared to the other anesthetics. Under K/X, the left ventricular end diastolic diameter (LVdD) was increased (0.60±0.01 cm) compared to conscious animals (0.41±0.02 cm), ISO (0.51±0.02 cm), and TP (0.55±0.01 cm), P<0.0001. The heart rate observed with K/X was significantly lower than in the remaining conditions. These results indicate that the K/X combination may be the best anesthetic option for the in vivo assessment of cardiac systolic function in hamsters, being associated with a lower LVEF reduction compared to the other agents and showing values closer to those of conscious animals with a lower dispersion of results.

Impact of subclinical hypothyroidism treatment in systolic and diastolic cardiac function / Impacto do tratamento do hipotireoidismo subclínico na função cardíaca sistólica e diastólica

OBJECTIVE: To evaluate the effects of levothyroxine (L-T4) replacement in echocardiographic parameters of middle-aged women with subclinical hypothyroidism (SH). SUBJECTS AND METHODS: This was a randomized, double-blind, placebo-controlled study. Echocardiographic evaluation was carried out at baseline and one year after restoration of euthyroidism. Thirty-three women with SH were assigned to one of two groups (L-T4 or placebo). RESULTS: The two groups had similar basal characteristics. There was a significant deterioration of left ventricular Tei index after one year of placebo use, which differed from the effect of L-T4 replacement (+0.086 ± 0.092 vs. -0.014 ± 0.012; p = 0.047). There was also a slight reduction in cardiac output and cardiac index with placebo use, which was not different from L-T4 effect. CONCLUSION: Results suggest a positive impact of L-T4 replacement in cardiac function of middle-aged women with SH.

OBJETIVO: Avaliar os efeitos da reposição de levotiroxina (L-T4) nos parâmetros ecocardiográficos em mulheres de meia-idade com hipotireoidismo subclínico (HS). SUJEITOS E MÉTODOS: Realizado estudo duplo-cego, controlado com placebo com avaliação dos parâmetros ecocardiográficos no início e um ano após o restabelecimento do eutireoidismo. Trinta e três mulheres foram incluídas em dois grupos (uso de L-T4 ou placebo). RESULTADOS: Os dois grupos tinham características basais similares. Houve uma significativa piora do índice TEI do ventrículo esquerdo no grupo que usou placebo por um ano. Já no grupo em reposição com L-T4 observou-se uma leve melhora desse índice (+0,086 ± 0,092 vs. -0,014 ± 0,012; p = 0,047). Ocorreu também uma leve redução no débito cardíaco e no índice cardíaco com placebo, os quais não diferiram do efeito da reposição de L-T4. CONCLUSÃO: Os resultados sugerem um impacto positivo com a reposição de L-T4, na função cardíaca de mulheres de meia-idade, com HS.

NaCl plus chitosan as a dietary salt to prevent the development of hypertension in spontaneously hypertensive rats

The effect of NaCl plus 3% chitosan on the systolic blood pressure of spontaneously hypertensive rats (SHR) were evaluated and compared with NaCl plus KCl (NaCl, 49.36% + KCl 49.36%) and chitosan or NaCl treatment alone. In SHR, administration of NaCl plus chitosan (44 mM Na/day) for two months significantly decreased the systolic blood pressure greater than of NaCl plus KCl and NaCl alone. NaCl plus chitosan resulted, though not statistically significant, in decreased urinary Na+ excretion and decreased blood urea nitrogen levels. Urinary creatinine of NaCl plus chitosan was slightly decreased compared to 3 treated groups. Serum electrolytes levels, however, remained unchanged. The combination of NaCl and chitosan may be superior to the conventional use of NaCl plus KCl or NaCl alone in the prevention of hypertension. Even though these supplementary diets have demonstrated potential anti-hypertensive effects in the experimental animal model, further research is needed before any recommendations can be made.

Effect of treatment on myocardial performance index (MPI) in chronic severe anaemia.

Anaemia is a common ailment in developing countries which imposes mechanical load on heart. Myocardial Performance index (MPI) was evaluated by apex cardiogram (ACG) in 30 patients suffering from chronic severe anaemia (CSA) (with hemoglobin level less than 6 gm% and at least more than 3 months duration) before and after treatment in the age group of 20-40 years and compared with age and sex matched healthy controls. MPI was measured by simultaneous recordings of apex cardiogram, carotid arterial pulse, electrocardiogram and phonocardiogram on four channel polyrite (INCO). There was considerable increase (P<0.001) in heart rate (HR), left ventricular ejection time (ET) (P<0.02), shortening of isovolumic contraction time (ICT) (P<0.001), with no significant change in isovolumic relaxation time (IVRT) in anaemia versus controls. On treatment of anaemia HR and ET decreases (P<0.001), ICT increases (P<0.01) without any change in IVRT. Our findings indicate that performance of myocardium is improved after treatment. So treatment should be instituted as early as possible.

[Therapeutic effects of carvedilol on systolic function in children with dilated cardiomyopathy and heart failure]

Heart Failure [HF] and Dilated Cardiomyopathy [DCMP] are two common heart diseases among children. Carvedilol is the third generation of beta-blocker and although it has been approved in adults, very little is known about its safety, efficacy and dosing profile in children. This study is to evaluate the efficacy and safety of Carvedilol in children with HF or DCMP. This is a randomized double-blind study. We studied 30 patients with HF or DCMP for 6 months. 16 patients [2 DCMP and 14 HF] underwent standard medical therapy in addition to Carvedilol and the remained ones [2 DCMP and 12 HF] received the same regimen, except the placebo instead of Carvedilol. We visited all patients on a monthly basis program and echocardiographically, evaluated them for their systolic function indices including LVEF [Left Ventricular Ejection Fraction], EPSS [E Point Septal Separation], LVESV [Left Ventricular End Systolic Volume] and LVEDV [Left Ventricular End Diastolic Volume]. Data were analyzed by t-test and Mann-Whitney test. After 6 months of therapy, most of systolic function indices showed a more significant improvement in the Carvedilol group, including increase of LVEF [P=0.033] and decrease of EPSS [P=0.008] and LVESV [P=0.019]. No significant side-effects were observed in our patients. Pearson correlation coefficient between some variables showed further improvement of LVEF and EPSS in males. Also, response of cardiomyopathic patients to Carvedilol was more than patients with heart failure. The Carvedilol is an effective and safe remedy for treatment of children with HF and DCMP

Hemodynamic Effects of Gabapentin in Rats

Gabapentin has been known to elicit the antinociceptive effect. However, little has been known about the effect of gabapentin on the cardiovascular system. The author's aim of this experiment was to examine the hemodynamic effects of gabapentin. Male Sprague-Dawley rats were used. Intrathecal or intracerebroventricular catheters were implanted and gabapentin was delivered through each catheter or directly into the peritoneal cavity. For hemodynamic measurements, catheters were inserted into the tail artery. Blood pressure and heart rate were measured over 60 min following administration of gabapentin. Intrathecal and intraperitoneal gabapentin did not induce significant changes of hemodynamics over the 60 min compared to the baseline value. Intracerebroventricular gabapentin increased systolic and diastolic blood pressure, but there is no statistically difference in blood pressure change according to the dose.

Adenosina exógena y disfunción postisquémica en el corazón aislado de conejo / Exogenous adenosine and postischemic dysfunction in the isolated rabbit heart

Es conocido que la adenosina atenúa las alteraciones sistólicas de la disfunción ventricular postisquémica ("miocardio atontado"), pero poco se conoce acerca de los efectos de este compuesto sobre las alteraciones diastólicas y, por otra parte, existe controversia sobre la importancia del momento de su administración. El objetivo del presente trabajo fue determinar los efectos de la adenosina cuando es administrada: a) desde antes de la isquemia y b) a partir del inicio de la reperfusión, sobre la función sistólica y diastólica del "miocardio atontado". Un objetivo adicional fue determinar se la adenosina modifica la liberación de creatinfosfokinasa (CPK) y lacticodeshidrogenasa (LDH) que ocurre en el "miocardio atontado". Se utilizaron corazones aislados isovolúmicos de conejo, perfundidos según la técnica modificada de Langendorff, y sometidos a isquemia global de 15 minutos y reperfusión de 30 minutos. La colocación de un balón de látex en el ventrículo izquierdo, conectado a un transductor de presión, permitió registrar la presión intraventricular izquierda, su primera derivada (dP/dt) y la presión de perfusión coronaria (PP). Se midieron, la presión diastólica final (rigidez diastólica), la PP y la máxima velocidad de ascenso y de descenso de la presión (+dP/dtmáx y -dP/dtmáx, respectivamente). Se calculó la presión desarrollada de ventrículo isquierdo, el cociente entre la +dP/dtmáx y dP/dtmáx (+P/-P) y la constante de tiempo de decaimiento de la presión ventricular durante la fase de relajación isovolúmica (t, Tau). La adenosina, adminstrada tanto antes del período de isquemia como al comienzo de la reperfusión, atenuó las alteraciones sistólicas y la rigidez diastólica sin modificar la relajación isovolúmica. Asimismo, la adenosina no modificó significativamente la liberación de CPK y LDH.

Efecto del enalaprilato sobre la disfuncion postisquemica sistolica y diastolica (miocardio atontado) en el corazon aislado de conejo / Effect of enalaprilat on postischemic systolic and diastolic dysfunction (stunned myocardium) on the isolated rabbit heart

El objetivo principal del trabajo fue determinar en el corazón aislado de conejo el efecto del Enalaprilato administrado: a) antes de la isquemia y b) en el momento de la reperfusión, sobre la función sistólica y diastólica del "miocardio atontado", y también sobre la fase de "hiperfunción" que ocurre precozmente en la reperfusión. Un segundo objetivo fue determinar si el enalaprilato modifica la liberación de lactato, creatinfosfoquinasa (CPK) y lacticodeshidrogenasa (LDH), que ocurre en el "miocardio atontado". Para esto utilizamos corazones de conejo perfundidos con la técnica de Langendorff, sometidos a isquemia global de 15 min y reperfusión durante 30 min y en los que la colocación de un globo de látex en el ventrículo izquierdo permitió medir la presión ventricular, y calcular la presión desarrollada, la maxima velocidad de ascenso y descenso de la presión (+ DP/dtmaxy -dP/dtmax, respectivamente), el cociente entre estas dos variables de velocidad (+ P/-P), y la constante de tiempo dirante la caída de la presión venricular (tau, tau). El Enalaprilato administrado tanto antes de la isquemia, como al comienzo de la reperfusión, atenúo la disfunción postisquémica sistólica, y la fase precoz de "hiperfunción". El efecto sobre la función diastólica fue diferente según se considere el componente activo o el pasivo: mientras que no modificó las lteraciones la relajación, atenuó significantemente el aumento de la rigidez miocárdica. El Enalaprilato también disminuyó la cantidad de lactato en el efluente durante la reperfusión, pero no modificó la liberación de CPK y LDH.

effect of epinephrine in local anesthetic solutions on the blood pressure of young normotensive females following dental infiltrations

To investigate the effect of epinephrine in local anesthetic solutions on systolic and diastolic blood pressures. A buccal infiltration injection of 1.8 ml lignocaine 2% with epinephrine 1:100,000 [18 ug] was administered to normotensive female dental students in conjunction with periodic blood pressure measurements lasting until 15 minutes after the injection. College of Dentistry, King Saud University, Riyadh, Saudi Arabia. There was a statistically significant fall in both the systolic and diastolic pressures starting immediately after removal of the needle from the tissues; the systolic pressure continued to fall for ten minutes and the diastolic pressure for seven minutes, after which they started to rise again. Local anesthetics that contain epinephrine lower the systolic and diastolic blood pressures of normotensive patients after dental infiltrations

Heterometric regulation and calcium sensitivity of the infarcted rat heart

The surviving hypertrophied muscle remaining after myocardial infarction in rats is less sensitive to extracellular Ca2+ than the normal myocardium. Since the inotropic effect of Ca2+ is modulated by sarcomere lenght, the present study was undertaken to determine if Ca2+ desensitization of infarcted left ventricles (LV) can be modulated by increasing the diastolic pressure (DP). Rats submitted to left coronary artery ligation (N+11) or sham-operation (N=9) were killed 8-10 days later and their hearts perfused by the Langendorff technique. A balloon was introduced into the LV cavity to measure the isovolumic systolic pressure (ISP) produced by DP changes (0 to 25 mmHg) at three Ca2+ concentrations (0.8, 1.25 and 2.5 mM). In control hearts submitted to a DP of mmHg, the ISP increased from 36ñ3 to 63ñ4 and to 74ñ4 mmHg as external Ca2+ was changed from 0.8 to 1.25 and to 2.5 mM, respectively. in contrast,in infarcted hearts submitted to the same DP and Ca2+ concentrations, the ISP increased from 19ñ2 to 26ñ2 and to 27ñ3 mmHg. The depressed response to Ca2+ was not modified by increasing DP up to 25 mmHg, the greatest DP tested. At this DP, ISP increased from 75ñ4 to 103ñ5 and 114ñ5 mmHg control hearts and from 45ñ2 to 54ñ3 and to 55ñ4 mmHg in infarted hearts. Ventricular function curve normalization in relation to a DP of 5 mmHg, indicated that the relative increases of ISP as a function of DP, produced by infarcted hearts, were higher than controls for DP higher than 10 mmHg. These results indicate that indicate that desensitization to extracellular Ca2+ of infarcted hearts cannot be reduced by increasing preload levels. However, the depressed mechanical response may be partially compensated for by an improvement of the length-dependent contractile response of the hypertrophied muscle surviving infarction

Effect of treatment on systolic time intervals in systemic arterial hypertension.

Twenty six hypertensive patients and 25 control subjects were studied and their systolic time intervals (STI) were measured. It was found that an alteration in STI, signifying left ventricular dysfunction sets in most of the hypertensives earlier than any evidence of left ventricular hypertrophy (LVH) by clinical, radiological or electrocardiographic criteria. The parameters affected are the PEP interval which shows prolongation and PEP/LVET ratio which is increased. After treatment the left ventricular performance was found to improve in those who did not reveal evidence of LVH. Thus STI may be a sensitive indicator of early left ventricular dysfunction in hypertensives and a useful guide to assess improvement after treatment at a stage when other non-invasive methods are not so useful.