Extracranial Sonography Research Articles

Internal carotid artery blood flow and pulsatility index in cognitively impaired people with chronic heart failure.

Mild cognitive impairment and dementia are common and serious co-morbidities in people with chronic heart failure (HF) as they increase hospitalization rates, mortality and health care costs. Upon other factors, dysregulated cerebral perfusion might contribute to brain pathology. We aimed to evaluate the association of non-invasively measured blood flow (BF) and pulsatility index (PI) of the internal carotid artery (ICA) with (i) chronic HF parameters, (ii) brain morphologic measures and (iii) cognitive impairment. This post-hoc analysis of the observational, prospective Cognition.Matters-HF study included 107 chronic HF patients without atrial fibrillation or carotid artery stenosis (aged 63±10years; 19% women). Using extracranial sonography, we measured ICA-BF and ICA-PI 1.5cm distal of the carotid bifurcation. Brain magnetic resonance imaging was performed on a 3-Tesla scanner to quantify cerebral atrophy, hippocampal atrophy and white matter hyperintensities. Extensive neuropsychological testing tested the cognitive domains intensity of attention, visual/verbal memory and executive function (including its subdomains selectivity of attention, visual/verbal fluency and working memory) using a comprehensive test battery. (i) Neither ICA-BF (median 630 (quartiles 570, 700) mL/min) nor ICA-PI (1.05 (0.96. 1.23)) related to left ventricular ejection fraction, left atrial volume index or NT-proBNP. (ii) Higher ICA-PI (r=0.25; P=0.011), but not ICA-BF (r=0.08; P=0.409), associated with increased volume of white matter hyperintensities beyond ageing, while neither ICA-PI nor ICA-BF related to cerebral or hippocampal atrophy indices. (iii) ICA-BF, but not ICA-PI, positively correlated with age-adjusted T-scores of executive function (r=0.38; P<0.001) and its subdomains working memory (r=0.32; P<0.001) and visual/verbal fluency (r=0.32; P<0.001). In a multivariate linear model of executive function, only ICA-BF (T=3.79; P<0.001), but not HF or magnetic resonance imaging parameters, remained a significant correlate of executive function. ICA-BF and ICA-PI, measured in broadly available extracranial sonography, independently related to measures of functional and structural brain changes in people with chronic HF, respectively. Due to limitations of this cross-sectional approach without a healthy control group, larger controlled longitudinal studies are needed to further elucidate the role of ICA-BF dysregulation and its implication for clinical care in this vulnerable cohort.

Detection of Cardiac Right-to-Left Shunts by Contrast-Enhanced Harmonic Carotid Duplex Sonography

Paradoxical embolization by cardiac right-to-left shunts (RLS) is increasingly recognized as an important factor for embolic stroke. Contrast-enhanced transcranial Doppler sonography (ce-TCDS) is an established diagnostic tool for RLS detection but is frequently limited because of an inadequate temporal acoustic bone window. The purpose of this study was to determine whether extracranial sonography (ECS) using harmonic frequencies improves detection of RLS. Extracranial color duplex sonography using harmonic frequencies enables visualization of even single ultrasound contrast agent microbubbles because of oscillation. Patients with stroke and positive RLS findings on transesophageal echocardiography underwent a simultaneous extracranial and transcranial sonographic examination of the proximal common carotid artery (CCA) and middle cerebral artery (MCA) on the same side. A Valsalva strain was performed for 10 seconds after intravenous bolus injection of a galactose-based nontranspulmonary contrast agent. The B-mode frame sequences of the transverse plane of the CCA obtained by harmonic ECS and the ce-TCDS recordings of high-intensity transient signals from the MCA were analyzed offline. In all patients with RLS, the shunts could be identified by harmonic ECS. A close correlation could be seen between the count of visualized microbubbles in the CCA and the number of high-intensity transient signals detected on ce-TCDS in the ipsilateral MCA. The results of this study indicate that contrast-enhanced ultrasound harmonic imaging of the CCA using a Valsalva strain might be an optional screening tool for detection of cardiac RLS in patients with insufficient acoustic bone windows.