Antihypertensive treatment with a vasodilating beta-blocker, carvedilol, in chronic hemodialysis patients.

Carvedilol is an antihypertensive agent which displays unselective beta-blocking, alpha 1-blocking and antioxidant properties. It is primarily metabolized by the liver and excreted via the biliary system. The compound is highly lipophilic and strongly bound to plasma proteins. Consequently, there is no elimination during hemodialysis. The efficacy, safety, and pharmacokinetic profile of carvedilol titrated to effect were investigated in an open clinical trial in 15 long-term hemodialysis patients with arterial hypertension over a period of 12 weeks. The drug was administered only on days without dialysis. After a wash-out phase of one week, carvedilol was started in a dose of 12.5 mg per day. All 15 patients were titrated according to the antihypertensive effect to a daily dose of 25 mg of carvedilol. Carvedilol was effective in lowering blood pressure in hemodialysis patients (RR systolic: 170 +/- 11 vs. 144 +/- 9 mmHg; RR diastolic: 98 +/- 10 vs. 85 +/- 10 mmHg). The pharmacokinetic parameters of carvedilol and its active metabolite M2, assessed in 12 of the 15 patients, were not influenced by the lack of renal function or intermittend haemodialysis. In particular, there was no accumulation of carvedilol or its metabolite M2. In terms of side effects, three patients had to be withdrawn from the trial, because of hypoglycemia (n = 1), insufficient blood pressure control (n = 1) and prolonged hypotension (n = 1). Taken together, these results indicate that carvedilol is a safe and efficacious antihypertensive agent which can be used in patients maintained by maintenance dialysis treatment.

Radiation dose exposure of computed tomography coronary angiography: comparison of dual-source, 16-slice and 64-slice CT.

BACKGROUND: Dual-source CT (DSCT) promises a significant reduction of radiation dose exposure for coronary CT angiography (CTA). Large studies on radiation dose estimates are rare. OBJECTIVE: To compare radiation dose estimates of DSCT with 16- and 64-slice multidetector CT (MDCT) for non-invasive coronary angiography. PATIENTS AND DESIGN: Retrospective data analysis was performed on 292 patients: 56 patients were examined with 16-slice MDCT, 38 patients with 64-slice MDCT and 202 patients using DSCT. The effective dose (ED) estimates were calculated for all patients from the dose-length product and the conversion factor k (0.017 mSv/mGy/cm), as recommended by current guidelines. RESULTS: The mean (SD) ED for patients examined by 16-slice MDCT was 9.8 (1.8) mSv, for 64-slice MDCT 8.6 (2.8) mSv and for DSCT 11.4 (7.2) mSv. With a protocol of 100 kV tube voltage and 110 ms ECG pulsing window the mean (SD) ED was 3.8 (1.7) mSv for DSCT scanning. When DSCT with a tube voltage of 100 kV was used, a significant inverse correlation between heart rate and radiation dose exposure was found. CONCLUSIONS: When standard protocols for coronary CTA with 16-, 64-slice MDCT and DSCT scanners are used, the radiation dose is still high. However, using optimised and individually adjusted protocols low estimated radiation doses can be achieved.

Left ventricular adaptation after atrial septal defect closure assessed by increased concentrations of N-terminal pro-brain natriuretic peptide and cardiac magnetic resonance imaging in adult patients.

OBJECTIVE: To determine in an observational study whether N-terminal pro-brain natriuretic peptide (NT-proBNP) is raised in patients with an atrial septal defect (ASD) and whether concentrations change after interventional closure. METHODS: 12 patients (6 men, mean (SD) age 44.4 (18.6) years) with a moderate sized ASD type II (23.3 (4.5) mm, pulmonary to systemic flow ratio 2.1 (0.68)) were investigated. In all patients a magnetic resonance imaging (MRI) study was performed and NT-proBNP was assessed at baseline and early (9 (13) days) and late (138 (64) days) after intervention. RESULTS: Concentrations of NT-proBNP were found to be within the normal range at baseline (median 87 pg/ml, interquartile range 65-181 pg/ml) but increased early after the interventional closure (315 pg/ml, 133-384 pg/ml, p = 0.005 versus baseline). The increase of NT-proBNP was associated with an increase in left ventricular dimensions as assessed by MRI (left ventricular end diastolic volume 104 (27) ml to 118 (27) ml, p = 0.003). Late after ASD closure NT-proBNP returned to baseline concentrations (102 pg/ml, 82-188 pg/ml, p = 0.004 versus early follow up). CONCLUSION: These findings suggest the presence of transitory haemodynamic stress during adaptation of the left ventricle after ASD closure, which may contribute to the understanding of the pathological mechanism of acute heart failure and delayed improvement of exercise capacity after ASD closure.

Left atrial myxoma diagnosed and characterized by cardiac magnetic resonance imaging.

A 71 year old man was referred for MRI investigation of the heart. He had a history of progressive dyspnea. Due to his echocardiographical findings and the known history of permanent atrial fibrillation, his cardiologist suspected atrial thrombi. MRI investigation of the heart showed a left atrial mass pedunculated at the atrial septum which showed signal enhancement after intravenous administration of gadolinium-DTPA. Left atrial myxoma was suspected. The patient underwent surgery with resection of the tumor and patch-occlusion of the atrial septum. Histology confirmed a polypoid cardial myxoma.