Design of an ultrasonic physiotherapy system with pulse wave feedback control.

BACKGROUND: Due to different physical and biological mechanisms behind ultrasound hyperthermia and phonophoresis, the requirement for ultrasound power, frequency and control modes varies. OBJECTIVE: This paper introduces an adaptive ultrasonic physiotherapy system based on real-time surveillance over physiological characteristics of the patients, which in turn assists the individual treatment and dose limitation in auxiliary rehabilitation. METHODS: The method essentially takes advantage of distinctive characteristics of two different phases (systole and diastole) of the human cardiac cycle as a medium for modulation. The abundance of blood flow during systole enables energy exchange for hyperthermia while blood flow insufficiency caused by diastole assists in drug penetration. Said method could improve the adjuvant therapy as it provides partial drug penetration and therapeutic dosage control. RESULTS: By adjusting time window and intensity of multi-frequency ultrasound, it is possible to reduce the irradiation dosage to around 22% of that during continuous irradiation at 1 MHz. The method shows high potential in clinical practice. CONCLUSION: Frequency-tuning ultrasound therapy would be more efficient regarding drug penetration and improve the therapeutic efficacy of hyperthermia.

Long-term Risk of Heart Failure and Myocardial Dysfunction After Thoracic Radiotherapy: A Systematic Review.

BACKGROUND: Chest irradiation is a commonly used treatment for malignancy, with demonstrated symptomatic and survival benefit. The frequency and presentation of cardiovascular complications of radiotherapy remains unclear. METHODS: We performed a systematic review to evaluate the prevalence and manifestations of myocardial dysfunction (asymptomatic and symptomatic) in long-term cancer survivors treated with radiotherapy. RESULTS: Thoracic radiotherapy is associated with increased risk of heart failure in long-term follow-up, with hazard ratios ranging from 2.7 to 7.4 for Hodgkin lymphoma, and 1.5-2.4 for breast cancer. Although ejection fraction is often normal, systolic dysfunction has been more widely reported with modern techniques including 2-dimensional speckle strain and cardiac magnetic resonance. This might have implications for the selection of patients for cardioprotection. Despite common emphasis, diastolic functional abnormalities were infrequent in the long term. A limited amount of data suggest that right ventricular dysfunction is important in this population. CONCLUSIONS: The reports were heterogeneous, used different treatments, end points, and definitions of myocardial dysfunction, and most studies on the cardiac consequences of radiotherapy involved small numbers of patients and were published decades ago, making it difficult to formulate definitive conclusions for the current era.

Increased left atrial size in obese children and its association with insulin resistance: a pilot study.

Subclinical cardiac abnormalities represent predisposing factors for cardiovascular disease (CVD) in obese subjects. The aim of this study was to evaluate early cardiac abnormalities in obese youth and the potential association with insulin resistance (IR). Thirty obese (12 males (M)/18 females (F); age = 11.5 ± 2.4 years; body mass index (BMI)-standard deviation score (SDS) = +2.1 ± 0.5) and 15 normal weight (10 M/5 F; age = 12.8 ± 3.1 years; BMI-SDS = +0.3 ± 0.9) children and adolescents underwent Doppler two-dimensional echocardiographic assessments of left atrial (LA) and ventricular (LV) geometry and LV diastolic function (peak early [E] and late waves, E wave deceleration time, myocardial flow velocities). Homeostasis model assessment of IR (HOMA-IR) was used as an IR index. LA size was increased in obese children, as indicated by higher LA diameter (4.9 ± 0.5 vs 4.1 ± 0.4 cm, p < 0.001), area (14.3 ± 2.5 vs 10.7 ± 2.0 cm(2), p < 0.001), and volume (33.8 ± 10.6 vs 23.7 ± 6.4 ml, p = 0.003). LV mass was also increased in obese children (87.0 ± 16.6 vs 68.8 ± 13.2 g, p = 0.003), who also showed subtle diastolic dysfunctions, as indicated by higher values of E (97.1 ± 14.3 vs 86.2 ± 11.9 cm/s, p = 0.02). All the above parameters were significantly associated with BMI-SDS (p < 0.05). In addition, HOMA-IR was independently associated with LA diameter, area, and volume (ß = 0.314, p = 0.040; ß = 0.415, p = 0.008; ß = 0.535, p = 0.001). CONCLUSION: Obese children feature increased LA size, which emerged to be mainly correlated to, and possibly driven by IR, suggesting an increased CVD risk. WHAT IS KNOWN: Left atrial and ventricular alterations have been reported in obese adults, and they represent predisposing factors for cardiovascular disease. There is some evidence suggesting that obese children show increased left ventricular mass and also increased atrial size, although with conflicting results. WHAT IS NEW: Obese normotensive children showed a moderately increased atrial size, subtle alterations in left cardiac diastolic function, and ventricular mass. An association between insulin resistance and left cardiac changes was found, although its mechanism remains to be determined.

The effect of radiotherapy on cardiac function.

BACKGROUND: Radiation-induced heart disease is a complication that may be encountered after radiotherapy (RT) of tumors in the vicinity of the heart. In this study, we aimed to evaluate the effect of RT on the heart, by comparing conventional and tissue Doppler echocardiography parameters obtained before and after RT. METHODS: Forty patients who had undergone RT for either lung or left breast cancer were included in the study. ECG, conventional, and tissue Doppler echocardiography were performed before and 4-6 weeks after RT. RESULTS: The mean value of the radiation dose applied to all regions of the heart was calculated as 13.1±2.2 Gy (maximum 41.7 Gy). The value for the left ventricle was 10.2±2.0 Gy (maximum 43.6 Gy). A decrease in early transmitral diastolic velocity (E), E/A ratio, EF, Em, and Em/Am, and an increase in E-wave deceleration time, isovolumic relaxation time, isovolumic contraction time, ejection time, and QTc were found after RT. CONCLUSION: We found detrimental effects of RT on systolic and diastolic cardiac functions and the electrical conduction system of the heart. Maximal prevention should be provided for the patients during RT.

Pulsed magnetic field induces angiogenesis and improves cardiac function of surgically induced infarcted myocardium in Sprague-Dawley rats.

OBJECTIVE: It was the aim of this study to investigate the impact of pulsed magnetic field (PMF) on ischemic myocardium, though it has been reported that PMF treatment is a safe and effective method to facilitate bone and cutaneous wound healing. METHODS: In this report, we describe a study in which 10 Hz 4 mT PMF and 15 Hz 6 mT PMF was used to treat rats with myocardial infarction (MI). RESULTS: After 28 days of treatment, the rats treated with 15 Hz 6 mT PMF exhibited decreased left ventricular end-diastolic pressure and accelerated maximum dp/dt of left ventricular pressure when compared with the untreated MI and the MI + 10 Hz 4 mT groups. Additionally, capillary density was increased and infarction area size was decreased in the MI + 15 Hz 6 mT group. Furthermore, the plasma vascular endothelial growth factor concentration and the protein expression of vascular endothelial growth factor receptor 2 in myocardial tissue were increased in rats of the MI + 15 Hz 6 mT group. CONCLUSION: This study shows that 15 Hz 6 mT PMF promotes myocardial angiogenesis and improves cardiac function after MI in rats. This suggests that there is a potential use for some PMF signal strengths in ischemic myocardial disease.

Influence of mast cells on structural and functional manifestations of radiation-induced heart disease.

Radiation-induced heart disease (RIHD), characterized by accelerated atherosclerosis and adverse tissue remodeling, is a serious sequelae after radiotherapy of thoracic and chest wall tumors. Adverse cardiac remodeling in RIHD and other cardiac disorders is frequently accompanied by mast cell hyperplasia, suggesting that mast cells may affect the development of cardiac fibrosis. This study used a mast cell-deficient rat model to define the role of mast cells in RIHD. Mast cell-deficient rats (Ws/Ws) and mast cell-competent littermate controls (+/+) were exposed to 18 Gy localized single-dose irradiation of the heart. Six months after irradiation, cardiac function was examined by echocardiography and Langendorff-perfused isolated heart preparation, whereas structural changes were assessed using quantitative histology and immunohistochemical analysis. Mast cell-deficient rats exhibited more severe postradiation changes than mast cell-competent littermates. Hence, mast cell-deficient rats exhibited a greater upward/leftward shift in the left ventricular (LV) diastolic pressure-volume relationship (P = 0.001), a greater reduction in in vivo LV diastolic area (from 0.50 +/- 0.024 cm in age-matched controls to 0.24 +/- 0.032 cm after irradiation; P = 0.006), and a greater increase in LV posterior wall thickness (from 0.13 +/- 0.003 cm in age-matched controls to 0.15 +/- 0.003 cm after irradiation; P = 0.04). Structural analysis revealed more pronounced postradiation accumulation of interstitial collagen III but less myocardial degeneration in hearts from mast cell-deficient rats. These data show that the absence of mast cells accelerates the development of functional changes in the irradiated heart, particularly diastolic dysfunction, and suggest that, in contrast to what has been the prevailing assumption, the role of mast cells in RIHD is predominantly protective.

Influence of a radiofrequency electromagnetic field on cardiovascular and hormonal parameters of the autonomic nervous system in healthy individuals.

The potential health risks of radiofrequency electromagnetic fields (EMFs) emitted by mobile phones are of considerable public interest. The present study investigated the hypothesis, based on the results of our previous study, that exposure to EMFs can increase sympathetic vasoconstrictor activity. Forty healthy young males and females underwent a single-blind, placebo-controlled protocol once on each of two different days. Each investigation included successive periods of placebo and EMF exposure, given in a randomized order. The exposure was implemented by a GSM-like signal (900 MHz, pulsed with 217 Hz, 2 W) using a mobile phone mounted on the right-hand side of the head in a typical telephoning position. Each period of placebo exposure and of EMF exposure consisted of 20 min of supine rest, 10 min of 70 degrees upright tilt on a tilt table, and another 20 min of supine rest. Blood pressure, heart rate and cutaneous capillary perfusion were measured continuously. In addition, serum levels of norepinephrine, epinephrine, cortisol and endothelin were analyzed in venous blood samples taken every 10 min. Similar to the previous study, systolic and diastolic blood pressure each showed slow, continuous, statistically significant increases of about 5 mmHg during the course of the protocol. All other parameters either decreased in parallel or remained constant. However, analysis of variance showed that the changes in blood pressure and in all other parameters were independent of the EMF exposure. These findings do not support the assumption of a nonthermal influence of EMFs emitted by mobile phones on the cardiovascular autonomic nervous system in healthy humans.

Cardiac function, perfusion, and morbidity in irradiated long-term survivors of Hodgkin's disease.

PURPOSE: The incidence of cardiotoxicity and clinical cardiac events following mantle irradiation (RT) in patients with Hodgkin's disease using modern techniques is controversial. The use of quantitative, prognostically validated noninvasive tests to assess systolic and diastolic cardiac function and regional myocardial blood flow may reveal preclinical abnormalities associated with subsequent clinical events of myocardial infarction, cardiac death, or angina. The goals of this study are to determine, through noninvasive measures, the presence and time course of alterations in cardiac systolic and diastolic function and of relative myocardial blood flow in long-term survivors of Hodgkin's disease, and assess their correlation with subsequent clinical cardiac end points. METHODS AND MATERIALS: Equilibrium radionuclide angiocardiography (ERNA) was used to assess left ventricular (LV) systolic and diastolic function by measuring LV ejection fraction (LVEF) and peak filling rate (PFR), respectively, in patients without known ischemic heart disease who received RT. Electrocardiography was performed to assess electrical cardiac function under conditions of rest and either exercise or dipyridamole vasodilator stress. Quantitative rest/stress myocardial perfusion imaging with thallium-201 and/or Tc-99m sestamibi was used to assess myocardial perfusion. Patients at least 1.0 year after RT were eligible if they were <50 years old at RT, had no known cardiac disease, and remained free of clinical recurrence of Hodgkin's disease. Fifty patients, ages 10.2-46.1 years (mean 26.0 +/- 8.6) at RT, were tested 1.1 to 29.1 years (mean 9.1 +/- 7.5) after RT. Seventeen of these patients were tested two times separated by 1.1 to 8.1 years. The mean central cardiac RT dose was 35.1 +/- 7.8 Gy (range 18.5-47.5) in daily 15-2.0 Gy fractions. Twelve patients were concomitantly irradiated to the left ventricle, usually through partial transmission left lung shields (mean 17.0 +/- 2.2 Gy, range 14.3-21.3). RESULTS: No patients had signs or symptoms of cardiac disease at the time of evaluation. The mean LVEF at the time of initial testing was 59.6 +/- 6.2% (n = 50; range 42-73%; normal > or =50%), and the mean peak filling rate (PFR) was 3.46 +/- 0.88 end diastolic volumes per second (EDV/s) (range 1.5-5.4 EDV/s; normal > or =2.54 EDV/s). The 12 patients also treated to the left ventricle had a normal mean ejection fraction that was lower (56.6 +/- 5.0%) than that of the other 38 patients (LVEF = 60.6 +/- 6.3%, p = 0.051) when initially evaluated. Average PFR was similar in the two groups. For the 15 patients who had repeat tests, changes in LVEF were generally modest in individual patients, and there was no change in the group mean. For all patients, no significant association was found between cardiac function indices and age at RT, dose, or interval from RT to testing. Myocardial perfusion scintigraphy demonstrated mild ischemia in one or more segments in two patients, and borderline normal perfusion in three patients. Rest and stress ECG testing demonstrated mild repolarization abnormalities in three, and one patient was abnormal at rest and had nondiagnostic changes with stress. CONCLUSIONS: Patients irradiated to the heart incidental to the treatment of Hodgkin's disease using modern techniques have generally normal measures of left ventricular function and myocardial perfusion. Modest differences in the normal left ventricular ejection fraction observed may be attributable to the cardiac volume irradiated. Some patients may manifest improved cardiac function as time from RT elapses, while a significant deterioration of ejection fraction was not observed and reduction in diastolic peak filling rate is uncommon. The previously reported increased risk of cardiac death may relate to use of older techniques of RT employing higher doses and lack of cardiac shielding, and uncontrolled patient selection with additional behaviors and cardiac risk factors.