Quantitative magnetic resonance perfusion imaging detects anatomic and physiologic coronary artery disease as measured by coronary angiography and fractional flow reserve.

OBJECTIVES: To evaluate the ability of quantitative perfusion cardiac magnetic resonance (CMR) to assess the hemodynamic significance of coronary artery disease (CAD) compared with well-established anatomic and physiologic techniques. BACKGROUND: Fractional flow reserve (FFR) is considered by many investigators to be a reliable stenosis-specific method to determine hemodynamically significant CAD. Quantitative perfusion CMR is a promising noninvasive approach to detect CAD but has yet to be validated against FFR. METHODS: This is a prospective study in patients with suspected CAD who underwent coronary angiography, FFR, and CMR assessments. The quantitative myocardial perfusion reserve (MPR) was calculated in 720 myocardial sectors (8 sectors/slice). The MPR was calculated from the ratio between stress and rest myocardial flow based on signal intensity time curves using deconvolution analysis. Stress was simulated with adenosine for both FFR and MPR. The MPR assessments were compared to FFR (n = 44 coronary segments) and quantitative coronary angiography (n = 108 segments) in the corresponding coronary territories. RESULTS: The MPR was 1.54 +/- 0.36 in segments with FFR < or =0.75 (n = 14) and 2.11 +/- 0.68 in those with FFR >0.75 (n = 30; p = 0.0054). An MPR cutoff of 2.04 was 92.9% (95% CI 77.9 to 100.0) sensitive and 56.7% (95% CI 32.8 to 80.6) specific in predicting a coronary segment with FFR < or =0.75. The MPR was 1.54 +/- 0.49 in coronary segments with > or =50% diameter stenosis (DS) (n = 47) and 2.13 +/- 0.80 in segments with <50% DS (n = 61; p < 0.001). An MPR cutoff of 2.04 was 85.1% (95% CI 71.1 to 99.2) sensitive and 49.2% (95% CI 33.6 to 64.8) specific in predicting CAD with > or =50% DS. CONCLUSIONS: Quantitative perfusion CMR is a safe noninvasive test that represents a stenosis-specific alternative to determine the hemodynamic significance of CAD.     

Sodium channel blockers alter slow-wave frequency of the rat stomach in vivo.

Treatment with sodium-channel-blocking agents is accompanied by a high incidence of gastrointestinal side effects. We therefore studied the influence of two sodium channel blockers, mexiletine and flecanaide, on gastric and jejunal myoelectrical activity of unanesthetized rats. Bipolar electrodes were implanted chronically on the serosal surface of the antrum or the jejunum of male rats (weight: 250-350 g). Electrical activity was recorded on a Polygraph starting on day 5 after the operation After 1 h of baseline recordings, either vehicle or an active drug was given randomly. Recordings were continued for 4 h after drug administration. Vehicle did not induce changes in slow-wave frequency. In contrast, gastric slow-wave activity significantly decreased after the administration of both mexiletine and flecanaide. Jejunal myoelectrical activity was only slightly affected by sodium channel blockade. The disruption of gastric myoelectrical activity may contribute to the side effects observed during chronic treatment with class I antiarrhythmic drugs.     

Transcatheter occlusion of the patent ductus arteriosus in infants: Experimental testing of a new Amplatzer device

Objectives: This study assessed the feasibility and efficacy of implanting a new miniaturized nitinol device to occlude the patent ductus arteriosus (PDA) in a newborn porcine model. Background: Transcatheter device closure is the standard of care for PDA in older children and adults. Currently available technology is not designed for the newborn infant. Methods: The Amplatzer Duct Occluder II 0.5 is a new transcatheter Nitinol device without fabric designed to close the PDA with small aortic and pulmonary artery structures. The device was implanted in 8 infant pigs (average weight 2,400 g) after balloon dilation of PDA (average diameter 2.7 mm, average length 5.8 mm) with immediate, ～ 7, ～ 30, and ～ 90 day follow‐up by echocardiography, angiography, and final pathological examination. Half were implanted arterial, and half venous. Results: The device was successfully implanted in all animals. There was complete occlusion of the PDA in all cases without obstruction of the pulmonary arteries or aorta. There was complete late endothelialization without thrombus. The only complication was transection of a femoral artery accessed by cutdown. Conclusions: The success of this animal study confirms safety and feasibility of the Amplatzer Duct Occluder II 0.5 (now known as the ADO II AS) for use when the aorta and pulmonary arteries are small. Consideration can be given to transcatheter closure of the PDA in preterm and other small infants with this device. © 2011 Wiley Periodicals, Inc.