Ultrasound at 27 kHz increases tissue expression and activity of nitric oxide synthases in acute limb ischemia in rabbits.

Transcutaneous low-frequency ultrasound (US) preserves myocardial and skeletal muscle viability by increasing tissue perfusion through an undefined nitric oxide (NO)-dependent mechanism. We have examined whether US increases tissue expression and activity of the three nitric oxide synthase (NOS) isoforms: endothelial (eNOS), neuronal (nNOS) and inducible (iNOS). The two femoral arteries of four New Zealand rabbits were ligated for a total of 120 min. After 60 min of ligation, transcutaneous low-frequency US (27 kHz, 0.13 W/cm2) was applied for 60 min to one thigh, while the contra-lateral artery served as a control (total ischemia time=120 min). Calcium-dependent (cNOS) and -independent (ciNOS) NOS activity, and concentration of total eNOS, ser-1177 phosphorylated eNOS (P-eNOS), nNOS and iNOS were then determined in the gracilis muscle. Compared with the control, US application significantly increased cNOS activity [3.34+/-0.28 versus 3.87+/-0.10x1000 counts per minute (cpm), respectively, p=0.031] and ciNOS activity (1.99+/-0.09 versus 3.26+/-0.68 cpm, respectively, p<0.001). Western immunoblotting revealed a significant increase in protein content of both iNOS (184.5+/-1.08%; p<0.0001) and P-eNOS (381.5+/-2.47%; p<0.001), with only a small increase in total eNOS and nNOS expression. In conclusion, application of transcutaneous low-frequency US to ischemic muscular tissue significantly increases both cNOS and ciNOS activity by increasing eNOS phosphorylation and iNOS expression, respectively.

Hypercalcemia-induced ST-segment elevation mimicking acute myocardial infarction.

We describe a patient who presented with abdominal pain radiating to the chest and ST elevation in the precordial leads, mimicking acute myocardial infarction. Urgent coronary angiography revealed normal coronary arteries and his serum troponin has not increased. Subsequently, he was found to have severe hypercalcemia. ST segment elevation resolved after correction of hypercalcemia. This phenomenon of ST elevation secondary to hypercalcemia has been described only two times in the English literature to date.

Transcutaneous ultrasound-facilitated coronary thrombolysis during acute myocardial infarction.

In preclinical experiments, the combination of transcutaneous, low-frequency ultrasound and thrombolytic therapy has shown improved patency rates over thrombolytics alone. A total of 25 patients with myocardial infarction were treated with a thrombolytic agent and adjunctive transcutaneous ultrasound. No unanticipated major adverse events were observed.

Diastolic dysfunction and COPD exacerbation.

INTRODUCTION: Chronic obstructive pulmonary disease (COPD) exacerbation is a frequent cause of hospital admissions. In one-third of patients, exacerbations have no known cause. We studied whether the presence of diastolic dysfunction (DD) in this subgroup of patients is associated with longer duration of hospitalization and more frequent exacerbations. METHODS: Retrospective chart review of 139 patients with COPD, 84 with DD, and 55 with normal diastolic function hospitalized for acute COPD exacerbation between November 2004 and December 2007 was done. Diastolic dysfunction was defined by the presence of relaxation, filling, or distensibility abnormalities of the left ventricle on transthoracic echocardiogram. RESULTS: Patients with DD had increased length of stay compared with patients without DD (mean: 4.02 +/- 1.8 days vs 3.24 +/- 1.20 days; P = 0.005). Patients with DD had 1.28 exacerbations requiring hospitalization per patient-year compared with 0.67 in the normal diastolic function group (P = 0.0067). CONCLUSIONS: Patients with COPD and DD had prolonged and more frequent hospitalizations for COPD exacerbations. These findings suggest that DD, a surrogate for increased left ventricular filling pressure, is common in patients with COPD exacerbations and may be associated with increased frequency of hospitalization.

Live three-dimensional echocardiography in evaluation of Alfieri mitral valve repair a case report.

Echocardiography plays a significant role in the evaluation of mitral valve repair. Three-dimensional(3D) echocardiography provides surgeon' views not obtainable by two-dimensional echocardiography. We report the live 3D echocardiographic evaluation of Alfieri mitral valve repair.

Sudden death prophylaxis in heart failure.

Sudden cardiac death (SCD) is the leading cause of mortality in heart failure (HF). Today the implantable cardioverter-defibrillator (ICD) has become a commonplace therapy around the world for patients with both ischemic and non-ischemic cardiomyopathy and an ejection fraction (EF) < or = 35%. However, EF alone does not discriminate between the modes of death from HF (sudden arrhythmic death vs. non-sudden death). Other risk statifiers, such as electrophysiologic study and microvolt T-wave alternans testing, should therefore be used in the appropriate settings to minimize the number of unnecessary device implants. In addition, left ventricular mechanical dyssynchrony has now become recognized as an additional major marker of cardiac mortality. Its assessment should entail echocardiography rather than measurement of the QRS duration. This will allow us to better integrate the ability of cardiac resynchronization therapy (CRT) in enhancing cardiac function with the ability of an ICD in preventing SCD. This review aims to: 1) give a synthesis of the published evidence regarding the value of implantable ICDs and CRT in the primary prophylaxis of SCD in HF; 2) discuss controversial clinical issues in this area; and 3) recommend practical device-based management strategies.