Evaluation of coronary bypass graft occlusion and stenosis with 64-detector-row computed tomography angiography.

BACKGROUND: A noninvasive imaging modality is desirable for the evaluation of coronary bypass graft stenosis and occlusion. PURPOSE: To prospectively evaluate the effectiveness of 64-detector-row computed tomography (DCT) for the assessment of coronary bypass grafts. MATERIAL AND METHODS: Forty-two patients (35 male, seven female, mean age 66.3 years) with 103 bypass grafts (32 arterial, 71 venous) were examined with 64-DCT. The evaluations were done by two radiologists blinded to the results of quantitative coronary angiography (QCA), used as the reference standard. RESULTS: All of the 26 occluded grafts, nine of the 10 stenosed grafts, and 66 of the 67 patent grafts were correctly diagnosed with 64-DCT angiography. The sensitivity, specificity, and positive and negative predictive values for 64-DCT in detecting graft stenosis were 90%, 99%, 90%, and 99%, respectively. For graft occlusion, all were 100%. No statistically significant difference was found between 64-DCT and QCA for the evaluation of bypass grafts. Intermodality and interobserver agreement were excellent. CONCLUSION: 64-DCT angiography is a reliable, noninvasive diagnostic method for the assessment of coronary bypass grafts. It can be considered as a useful tool for follow-up purposes and may function as a gatekeeper before invasive procedures.

Codon-anticodon interaction at the P site is a prerequisite for tRNA interaction with the small ribosomal subunit.

The arrival of high resolution crystal structures for the ribosomal subunits opens a new phase of molecular analysis and asks for corresponding analyses of ribosomal function. Here we apply the phosphorothioate technique to dissect tRNA interactions with the ribosome. We demonstrate that a tRNA bound to the P site of non-programmed 70 S ribosomes contacts predominantly the 50 S, as opposed to the 30 S subunit, indicating that codon-anticodon interaction at the P site is a prerequisite for 30 S binding. Protection patterns of tRNAs bound to isolated subunits and programmed 70 S ribosomes were compared. The results suggest the presence of a movable domain in the large ribosomal subunit that carries tRNA and reveal that only approximately 15% of a tRNA, namely residues 30 +/- 1 to 43 +/- 1, contact the 30 S subunit of programmed 70 S ribosomes, whereas the remaining 85% make contact with the 50 S subunit. Identical protection patterns of two distinct elongator tRNAs at the P site were identified as tRNA species-independent phosphate backbone contacts. The sites of protection correlate nicely with the predicted ribosomal-tRNA contacts deduced from a 5.5-A crystal structure of a programmed 70 S ribosome, thus refining which ribosomal components are critical for tRNA fixation at the P site.

Catheter-induced vasospasm in the right external iliac and femoral arteries during a cardiac diagnostic procedure.

Catheter-induced vasospasm of small caliber arteries, such as the coronary arteries, is frequently observed during cardiac catheterization, but obstruction of the large caliber arteries has not previously been reported. Here we present two cases in which femoral and external iliac arteries were totally obstructed due to spasm during diagnostic coronary angiography.

Use of intraventricular dispersion of the peak diastolic flow velocity as a marker of left ventricular diastolic dysfunction in patients with atrial fibrillation.

The aim of this study was to evaluate the use of intraventricular dispersion of the peak diastolic flow velocity as a marker of left ventricular diastolic dysfunction in patients with atrial fibrillation. Regional diastolic flow velocity patterns at 1, 2, and 3 cm away from the mitral tip toward the apex were simultaneously recorded with the mitral flow velocity pattern by using pulsed Doppler echocardiography in 24 patients with atrial fibrillation before electrical or medical cardioversion. Echocardiographic examination was repeated after 10 to 30 days (ie, at the time of recovery of left atrial mechanical functions) after cardioversion of atrial fibrillation in all patients. Thirteen patients were found to have diastolic dysfunction; the remaining 11 patients with a normal E/A ratio constituted the control group. Afterward, the data recorded before the cardioversion were analyzed for each patient. In subjects with normal diastolic function, the peak diastolic flow velocity (PDFV) at the mitral tips also was maintained at the positions 1 to 3 cm away from the tip in the left ventricular cavity (PDFV at the mitral tips: 0.84 m/s, PDFV at 3 cm: 0.85 m/s; P =.34). In contrast, the regional PDFV progressively decreased toward the apex in patients with diastolic dysfunction (PDFV at the mitral tips: 0.82 m/s, PDFV at 3 cm: 0.63 m/s; P =.0004). Only 77% of the initial velocity was maintained at 3 cm away from the mitral tips in patients with diastolic dysfunction, whereas almost 100% of the initial velocity was preserved in patients with normal diastolic function (P <.001). These findings suggest that the assessment of the intraventricular decrease in mitral PDFV may be used as a reliable marker of diastolic dysfunction in patients with atrial fibrillation.

Comparison of Angiographic and Clinical Outcome After Cutting Balloon and Conventional Balloon Angioplasty in Vessels Smaller than 3 mm in Diameter: A Randomized Trial.

OBJECTIVES: The purpose of the study was to evaluate and compare the immediate and six month follow-up angiographic and clinical outcome of cutting balloon angioplasty and conventional balloon angioplasty in small vessels (less than 3 mm in diameter). METHODS AND RESULTS: Between August 1995 and August 1996 a total of 71 eligible symptomatic patients with angiographically proven significant lesions in their coronary arteries smaller than 3 mm and requiring revascularization, were randomized to receive treatment by either cutting balloon angioplasty (CB) or conventional balloon angioplasty (BA). ÒStand-aloneÓ CB was performed on 51 lesions in 36 patients and BA on 47 lesions in 35 patients. Basic angiographic and clinical characteristics were similar in both groups. The overall procedural success rates for CB and BA groups were 92% and 97%, respectively. The immediate post-procedural minimal luminal diameter, residual stenosis and acute gain were similar in the CB and BA cohorts (1.93 +/- 0.36 mm, 24 +/- 12%, 1.18 +/- 0.45 mm vs. 2.01 +/- 0.34 mm, 22 +/- 9%, 1.26 +/- 0.35 mm, respectively). Total dissection rate and C-F dissections were fewer in the CB group (37%, 6% vs. 51%, 19%, respectively, p < 0.05). Six month follow-up angiographic restenosis rate was lower in the CB group (27% vs. 47%, p < 0.05). We also detected a significant difference of total number of all events at nine month clinical follow up (28% vs. 51%, p < 0.05). CONCLUSION: CB angioplasty can be performed with a comparable success rate to conventional BA in small vessels. Fewer bail-out procedures are needed as CB causes fewer and less severe dissections. There is also a significant reduction in six month restenosis rate. We suggest that CB might be a better option for revascularizing vessels smaller than 3 mm in diameter which are inherently more prone to immediate complications and late restenosis with BA.