Vehicle-mounted high-power microwave systems and health risk communication in a deployed environment.

Vehicle-mounted high-power microwave systems have been developed to counter the improvised explosive device threat in southwest Asia. Many service members only vaguely comprehend the nature of these devices and the nonionizing radio frequency (RF) radiation they emit. Misconceptions about the health effects of RF radiation have the potential to produce unnecessary anxiety. We report an incident in which concern for exposure to radiation from a high-power microwave device thought to be malfunctioning led to an extensive field investigation, multiple evaluations by clinicians in theater, and subsequent referrals to an Occupational Health clinic upon return from deployment. When acute exposure to RF does occur, the effects are thermally mediated and immediately perceptible--limiting the possibility of injury. Unlike ionizing radiation, RF radiation is not known to cause cancer and the adverse health effects are not cumulative. Medical officers counseling service members concerned about potential RF radiation exposure should apply established principles of risk communication, attend to real and perceived risks, and enlist the assistance of technical experts to properly characterize an exposure when appropriate.

The heaviest known operatively-excised aortic valve.

A 60-year-old man whose operatively excised stenotic and regurgitant aortic valve weighed nearly 15 g, approximately 30 times the normal weight in an adult, is described. To the investigators' knowledge, this is the heaviest aortic valve ever encountered in a human being.

Effect on right ventricular volume of percutaneous Amplatzer closure of atrial septal defect in adults.

In adult patients with atrial septal defects (ASDs), right ventricular (RV) cavity size may return to normal after operative closure. This study demonstrated improved RV volumes and right atrial areas in 20 adult patients after successful transcatheter closure of large ASDs. RV volumes decreased by 22%, 30%, and 41% at 1 day, 1 month, and 6 months, respectively, after the procedure. Right atrial areas decreased by 5%, 23%, and 26%, respectively, over the same time.

Comparison of Transesophageal and Transthoracic Echocardiographic Measurements of Mechanism and Severity of Mitral Regurgitation in Ischemic Cardiomyopathy (from the Surgical Treatment of Ischemic Heart Failure Trial).

Mitral regurgitation (MR) is common in ischemic heart disease and contributes to symptoms and mortality. This report compares the results of baseline transesophageal echocardiography (TEE) and transthoracic echocardiography (TTE) imaging of the mechanism and severity of functional MR in patients with ischemic cardiomyopathy in the Surgical Treatment for Ischemic Heart Failure (STICH) trial. Independent core laboratories measured both TTE and TEE images on 196 STICH participants. Common measurements to both models included MR grade, mitral valve tenting height and tenting area, and mitral annular diameter. For each parameter, correlations were assessed using Spearman rank correlation coefficients. A modest correlation was present between TEE and TTE for overall MR grade (n = 176, r = 0.52). For mechanism of MR, modest correlations were present for long-axis tenting height (n = 152, r = 0.35), tenting area (n = 128, r = 0.27), and long-axis mitral annulus diameter (n = 123, r = 0.41). For each measurement, there was significant scatter. Potential explanations for the scatter include different orientation of the imaging planes between TEE and TTE, a mean temporal delay of 6 days between TEE and TTE, and statistically significant differences in heart rate and blood pressure and weight between studies. In conclusion, TEE and TTE measurements of MR mechanism and severity correlate only modestly with enough scatter in the data that they are not interchangeable.

Comparison of B-type natriuretic peptide levels in patients with heart failure with versus without mitral regurgitation.

Functional mitral regurgitation (MR) occurs most often in patients with heart failure (HF) and is associated with an adverse prognosis. Recently, B-type natriuretic peptide (BNP) has been validated as a marker of cardiac function and prognosis. We sought to assess the relation between functional MR and BNP levels in patients with HF, and hypothesized that MR is associated with higher BNP levels. In all, 201 patients admitted with the diagnosis of HF had a transthoracic echocardiogram and measurement of BNP levels within 48 hours. MR was graded as none/trace, mild, moderate, or severe using recently published guidelines of the American Society of Echocardiography. BNP was measured by a commercially available instrument (Biosite). The relation of MR to BNP was assessed using multivariable linear regression methods with a Tobin estimation to account for the truncation of BNP values at an upper limit of 1,300 pg/ml. Mean age of the patients was 67 +/- 11 years. The median BNP level was 826 pg/ml. The etiology of HF was predominantly diastolic in 64 patients (32%); 137 patients (68%) had significant left ventricular (LV) systolic dysfunction. Mean LV ejection fraction was 37 +/- 17%. MR was present in 112 patients (56%). After adjusting for clinical, hemodynamic, and echocardiographic variables, only LV ejection fraction (p = 0.016) and moderate or severe MR (p = 0.023) were significantly associated with BNP. When MR was grouped as any MR versus no MR, only LV ejection fraction (p = 0.017) and any degree of MR (p = 0.029) were significantly associated with BNP.

Color flow imaging of the vena contracta in mitral regurgitation: technical considerations.

Qualitative grading of mitral regurgitation severity has significant pitfalls secondary to hemodynamic variables, sonographic technique, blood pool entrainment, and the Coanda effect. Volumetric and proximal isovelocity surface area methods can be used to quantitate regurgitant orifice area, regurgitant volume, and regurgitant fraction, but have several limitations and can pose technical challenges. The vena contracta width method provides a rapid and accurate quantitative assessment of mitral regurgitation severity, but is clinically underused. This article is intended to generate an understanding of the flow mechanics of the vena contracta and the sonographic technique required to provide consistent and accurate measurements of vena contracta width in patients with mitral regurgitation.

Anomalous cord from the raphe of a congenitally bicuspid aortic valve to the aortic wall producing either acute or chronic aortic regurgitation.

OBJECTIVES: This report calls attention to an unappreciated cause of both acute and chronic aortic regurgitation (AR). BACKGROUND: Although stenosis develops in most patients with a congenitally bicuspid aortic valve (BAV), in others with this anomaly, pure AR (no element of stenosis) develops, some in the absence of infection or other clear etiology. METHODS: We describe 5 men who underwent aortic valve replacement for pure AR associated with a BAV containing an anomalous cord attaching the raphe of the conjoined cusp near its free margin to the wall of the ascending aorta cephalad to the sinotubular junction. RESULTS: Three of these 5 patients had a history of progressive dyspnea, and the anomalous cord, which was intact at operation, appeared to cause chronic AR by preventing proper coaptation of the 2 aortic valve cusps. The other 2 patients heard a "pop" during physical exertion and immediately became dyspneic, and at operation, the anomalous cord was found to have ruptured. Prolapse of the conjoined aortic valve cusp toward the left ventricular cavity resulted in severe acute AR. CONCLUSIONS: This variant of the purely regurgitant BAV may cause either chronic AR (when the anomalous cord does not rupture) or acute severe AR (when the cord ruptures).

Successful ß cells islet regeneration in streptozotocin-induced diabetic baboons using ultrasound-targeted microbubble gene therapy with cyclinD2/CDK4/GLP1.

Both major forms of diabetes mellitus (DM) involve ß-cell destruction and dysfunction. New treatment strategies have focused on replenishing the deficiency of ß-cell mass common to both major forms of diabetes by islet transplantation or ß-cell regeneration. The pancreas, not the liver, is the ideal organ for islet regeneration, because it is the natural milieu for islets. Since islet mass is known to increase during obesity and pregnancy, the concept of stimulating pancreatic islet regeneration in vivo is both rational and physiologic. This paper proposes a novel approach in which non-viral gene therapy is targeted to pancreatic islets using ultrasound targeted microbubble destruction (UTMD) in a non-human primate model (NHP), the baboon. Treated baboons received a gene cocktail comprised of cyclinD2, CDK, and GLP1, which in rats results in robust and durable islet regeneration with normalization of blood glucose, insulin, and C-peptide levels. We were able to generate important preliminary data indicating that gene therapy by UTMD can achieve in vivo normalization of the intravenous (IV) glucose tolerance test (IVGTT) curves in STZ hyperglycemic-induced conscious tethered baboons. Immunohistochemistry clearly demonstrated evidence of islet regeneration and restoration of ß-cell mass.

Echocardiographic findings in professional hockey players.

Tissue Doppler imaging was used to evaluate the physiological and morphological response in athletes whose cardiac system must not only adapt to intense cardiovascular demands but also support sudden, transient changes in cardiac output. A total of 45 professional hockey players with a mean age of 24 years underwent a baseline transthoracic echocardiographic protocol after a typical morning workout; 12 healthy age- and gender-matched controls were evaluated as a means of comparison. The athletes in this study possessed larger left ventricular diastolic and systolic dimensions than the control group (5.5 ± 0.4 vs 4.9 ± 0.4 cm and 3.9 ± 0.4 vs 3.3 ± 0.4 cm, P < 0.0001). The increase in athletes' septal and posterior wall thickness was not substantial, nor was there a significant difference in left ventricular ejection fraction. The athletes demonstrated consistently larger left ventricular end-diastolic volume (196 ± 34 vs 136 ± 23 mL, P < 0.001) and end-systolic volume (87 ± 20 vs 57 ± 12 mL, P < 0.0001). They also had lower annular septal and lateral early diastolic and systolic tissue Doppler velocities compared with the control group. Thus, characteristic myocardial changes previously reported in elite athletes were also represented in professional hockey players. The lower left ventricular tissue Doppler velocities was a relatively unique finding and probably a consequence of lower postexertion preload levels compared with controls who were measured at rest.