Aortic distensibility in alkaptonuria.

INTRODUCTION: Alkaptonuria (AKU) is a rare inherited disorder of tyrosine metabolism resulting in an accumulation of homogentisic acid oxidation products in the joints and cardiovascular system. Aortic distensibility may be a non-invasive indicator of cardiovascular complications. Descending thoracic aortic distensibility in alkaptonuria has not been studied. METHODS: Patients diagnosed with alkaptonuria underwent Magnetic Resonance Imaging (MRI) and gated non-contrast and contrast-enhanced cardiovascular computed tomography. Using MRI cine images, aortic distensibility of the descending thoracic aorta was determined. RESULTS: Seventy-six patients with alkaptonuria were imaged. When compared to literature normal values, aortic distensibility in AKU was impaired (5.2 vs 6.2 × 10-3, p < .001). Aortic distensibility was inversely related to age (r = -0.6, p = .0001). Hypertensive patients with alkaptonuria had impaired distensibility compared to normotensive patients with alkaptonuria (4.6 vs 5.6 × 10-3, p = .03), and hyperlipidemic patients with alkaptonuria had impaired distensibility compared to non-hyperlipidemic patients with alkaptonuria (4.1 vs 6.0 × 10-3, p = .001). Male hypertensive patients with alkaptonuria had greater distensibility than their female counterparts (5.3 vs 2.9 × 10-3, p = .02). Similarly, male hyperlipidemic patients with alkaptonuria had greater distensibility than their female counterparts (4.8 vs 2.5 × 10-3, p < .01). Of patients with alkaptonuria, those with a coronary artery calcium (CAC) score greater than 100 had more impaired distensibility than those with a CAC score less than 100 (3.5 vs 5.1 × 10-3, p = .01) and those with aortic calcium score greater than 100 had impaired distensibility compared to those with an aortic calcium score less than 100 (3.2 vs 4.9 × 10-3, p = .02). Univariate analysis revealed age, aortic calcification, and hyperlipidemia to be significant factors of distensibility, and multiple regression analysis showed age as the only significant risk factor of distensibility. CONCLUSIONS: Patients with alkaptonuria have impaired aortic distensibility, which is likely an early marker for reduced cardiovascular health. Variables such as age, hypertension, hyperlipidemia, and aortic and coronary calcification were associated with impaired distensibility.

Effects of pericardial tamponade on the hemodynamics of aortic stenosis.

Compressive pericardial physiology (i.e., cardiac tamponade) reduces ventricular chamber volume/filling and cardiac output, which exacerbates coexisting hemodynamic derangements. In this hemodynamic rounds, we demonstrate the interaction of two hemodynamic conditions in one patient with acute pericardial tamponade in the setting of aortic stenosis (AS). Simultaneous pressures across the aortic valve before and after relief of cardiac tamponade demonstrate an acute and uncommon improvement in the hemodynamics of AS.

Comparison of professional medical society guidelines for appropriate use of coronary computed tomography angiography.

BACKGROUND: Multiple appropriate use criteria (AUC) exist for the evaluation of coronary artery disease (CAD), but there is little data on the agreement between AUC from different professional medical societies. The aim of this study is to compare the appropriateness of coronary computed tomography angiography (CCTA) exams assessed using multimodality AUC from the American College of Cardiology Foundation (ACCF) versus the American College of Radiology (ACR). METHODS: In a single-center prospective cohort study from June 2014 to 2016, 1005 consecutive subjects referred for evaluation of known or suspected CAD received a contrast-enhanced CCTA. The primary outcome was the agreement of appropriateness ratings using ACCF and ACR guidelines, measured by the kappa statistic. A secondary outcome was the rate of obstructive CAD by appropriateness rating. RESULTS: Among 1005 subjects, the median (5-95th percentile) age was 59 (37-76) years with 59.0% male. The ACCF criteria classified 39.6% (n = 398) appropriate, 24.2% (n = 243) maybe appropriate, and 36.2% (n = 364) rarely appropriate. The ACR guidelines classified 72.3% (n = 727) appropriate, 2.6% (n = 26) maybe appropriate, and 25.1% (n = 252) rarely appropriate. ACCF and ACR appropriateness ratings were in agreement for 55.0% (n = 553). Overall, there was poor agreement (kappa 0.27 [95% confidence interval 0.23-0.31]). By both AUC methods, a low rate of obstructive CAD was observed in the rarely appropriate exams (ACCF 7.1% [n = 26 of 364] and ACR 13.5% [n = 34 of 252]). CONCLUSIONS: Compared to ACCF criteria, the ACR guidelines of appropriateness were broader and classified significantly more CCTA exams as appropriate. The poor agreement between appropriateness ratings from the ACCF and ACR AUC guidelines evokes implications for reimbursement and future test utilization.

Reduced radiation dose with model based iterative reconstruction coronary artery calcium scoring.

Assessing coronary artery calcium (CAC) is a valuable tool for individualizing cardiac risk assessment. In CAC scanning, this technical report assesses the use of a true model-based iterative reconstruction algorithm using forward projected model-based iterative reconstruction ("FIRST") and assess whether FIRST allows for reduced radiation dose CAC scanning on 320-detector row computed tomography (320-CT). Here, 100 consecutive patients prospectively underwent reduced and standard dose scans. For the patients (59 ± 9 years, 61% male) stratified by Agatston categories 0, 1-10, 11-100, 101-400,> 400, agreement between reduced dose with FIRST versus standard dose with FBP was excellent at 81% (95% CI: 73-88%) with kappa 0.74 (95% CI: 0.64-0.85). Median radiation exposure was 75% lower for reduced (0.35 mSv) versus standard dose (1.37 mSv) scans. In conclusion, agreement was excellent for reduced dose with FIRST and standard dose with FBP in 320-detector row CT CAC imaging in well-established categories of cardiovascular risk. These methods make it possible to reduce radiation exposure by 75%.

Feasibility of low radiation dose retrospectively-gated cardiac CT for functional analysis in adult congenital heart disease.

BACKGROUND: The use of cardiac computed tomography (CT) in the evaluation of adult congenital heart disease patients is limited due to concerns of high radiation doses. The purpose of this study was to prospectively assess whether low radiation dose cardiac CT is feasible to evaluate ventricular systolic function in adults with congenital heart disease. METHODS: The study group included 30 consecutive patients with significant congenital heart disease who underwent a total of 35 ECG-gated cardiac CT scans utilizing a 320-detector row CT scanner. Each study included a non-contrast scan and subsequent contrast-enhanced retrospectively-gated acquisition. Effective radiation dose was estimated by multiplying the dose length product by a k-factor of 0.014mSv/mGycm. RESULTS: The mean age of the patients was 34.4±8.9years, 60% were men, and mean body mass index was 24.2±4.3kg/m2. A majority of patients (n=28, 93.3%) had contraindications to cardiac MRI. A tube potential of 80kV was used in 27 (77.1%) of the contrast-enhanced scans. The mean signal-to-noise and contrast-to-noise ratios were 11.5±3.9 and 10.3±3.7, respectively. The median radiation dose for non-contrast and contrast-enhanced images were 0.1mSv (0.07-0.2mSv) and 0.94mSv (0.5-2.1mSv), respectively. All 35 CT scans were successfully analyzed for ventricular systolic function. CONCLUSIONS: A low radiation contrast-enhanced, retrospectively-gated cardiac CT with a median radiation dose of less than 1mSv was successful in evaluating ventricular systolic function in 30 consecutive adult congenital heart disease patients who underwent a total of 35 scans.