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Background: Pulse wave velocity (PWV) is an indicator of arterial stiffness, and predicts cardiovascular events independently of blood pressure. Currently, PWV is commonly measured by the foot-to-foot technique thus giving a global estimate of large arterial stiffness. However, and despite its importance, methods to measure the stiffness of the ascending aorta are limited. Objective: To introduce a method for calculating local PWV in the human ascending aorta using non-invasive ultrasound measurements of its diameter (D) and flow velocity (U). Approach: Ten participants (four females) were recruited from Brunel University students. Ascending aortic diameter and velocity were recorded with a GE Vivid E95 equipped with a 1.5–4.5 MHz phased array transducer using M-mode in the parasternal long axis view and pulse wave Doppler in the apical five chamber view respectively. Groups of six consecutive heartbeats were selected from each 20 s run based on the most similar cycle length resulting in three groups for D and three for U each with six waveforms. Each D waveform was paired with each U waveform to calculate PWV using ln(D)U-loop method. Main results: The diastolic portions of the diameters or velocities waveforms were truncated to allow the pairs to have equal length and were used to construct ln(D)U-loops. The trimmed average, excluding 10% of extreme values, resulting from the 324 loops was considered representative for each participant. Overall mean local PWV for all participants was 4.1(SD = 0.9) m s−1. Significance: Local PWV can be measured non-invasively in the ascending aorta using ultrasound measurements of diameter and flow velocity This should facilitate more widespread assessment of ascending aortic stiffness in larger studies.

Objective: Hypertension is associated with reduced cerebral blood flow, but it is not known how this impacts on wave dynamics or potentially relates to arterial morphology. Given the location of the internal carotid artery (ICA) and risks associated with invasive measurements, wave dynamics in this artery have not been extensively assessed in vivo. This study explores the feasibility of studying wave dynamics in the internal carotid artery non-invasively. Approach: Normotensive, uncontrolled and controlled hypertensive participants were recruited (daytime ambulatory blood pressure 135/85 mmHg, respectively; n = 38). Wave intensity, reservoir pressure and statistical shape analyses were performed on the right ICA and ascending aorta high-resolution phase-contrast magnetic resonance angiography data. Main results: Wave speed in the aorta was significantly lower in normotensive compared to hypertensive participants (6.7 ± 1.8 versus 11.2 ± 6.2 m s−1 for uncontrolled and 11.8 ± 4.6 m s−1 for controlled hypertensives, p = 0.02), whilst there were no differences in wave speed in the ICA. There were no significant differences between the groups for the wave intensity or reservoir pressure. Interestingly, a significant association between the anatomy of the ICA and wave energy (FCW and size, r2 = 0.12, p = 0.04) was found. Significance: This study shows it is feasible to study wave dynamics in the ICA non-invasively. Whilst changes in aortic wave speed confirmed an expected increase in arterial stiffness, this was not observed in the ICA. This might suggest a protective mechanism in the cerebral circulation, in conjunction with the effect of vessel tortuosity. Furthermore, it was observed that ICA shape correlated with wave energy but not wave speed.

Liver dynamic contrast enhanced (DCE) MRI pharmacokinetic modelling could be useful in the assessment of diffuse liver disease and focal liver lesions, but is compromised by errors in arterial input function (AIF) sampling. In this study, we apply cardiac output correction to arterial input functions (AIFs) for liver DCE MRI and investigate the effect on dual-input single compartment hepatic perfusion parameter estimation and reproducibility. Thirteen healthy volunteers (28.7 ± 1.94 years, seven males) underwent liver DCE MRI and cardiac output measurement using aortic root phase contrast MRI (PCMRI), with reproducibility (n = 9) measured at 7 d. Cardiac output AIF correction was undertaken by constraining the first pass AIF enhancement curve using the indicator-dilution principle. Hepatic perfusion parameters with and without cardiac output AIF correction were compared and 7 d reproducibility assessed. Differences between cardiac output corrected and uncorrected liver DCE MRI portal venous (PV) perfusion (p = 0.066), total liver blood flow (TLBF) (p = 0.101), hepatic arterial (HA) fraction (p = 0.895), mean transit time (MTT) (p = 0.646), distribution volume (DV) (p = 0.890) were not significantly different. Seven day corrected HA fraction reproducibility was improved (mean difference 0.3%, Bland–Altman 95% limits-of-agreement (BA95%LoA) ±27.9%, coefficient of variation (CoV) 61.4% versus 9.3%, ±35.5%, 81.7% respectively without correction). Seven day uncorrected PV perfusion was also improved (mean difference 9.3 ml min−1/100 g, BA95%LoA ±506.1 ml min−1/100 g, CoV 64.1% versus 0.9 ml min−1/100 g, ±562.8 ml min−1/100 g, 65.1% respectively with correction) as was uncorrected TLBF (mean difference 43.8 ml min−1/100 g, BA95%LoA ±586.7 ml min−1/ 100 g, CoV 58.3% versus 13.3 ml min−1/100 g, ±661.5 ml min−1/100 g, 60.9% respectively with correction). Reproducibility of uncorrected MTT was similar (uncorrected mean difference 2.4 s, BA95%LoA ±26.7 s, CoV 60.8% uncorrected versus 3.7 s, ±27.8 s, 62.0% respectively with correction), as was and DV (uncorrected mean difference 14.1%, BA95%LoA ±48.2%, CoV 24.7% versus 10.3%, ±46.0%, 23.9% respectively with correction). Cardiac output AIF correction does not significantly affect the estimation of hepatic perfusion parameters but demonstrates improvements in normal volunteer 7 d HA fraction reproducibility, but deterioration in PV perfusion and TLBF reproducibility. Improved HA fraction reproducibility maybe important as arterialisation of liver perfusion is increased in chronic liver disease and within malignant liver lesions.

Intravascular photoacoustics (IV-PA) is an emerging atherosclerosis imaging modality that provides chemical-specific optical information of arterial walls with acoustic depth penetration and resolution. As lipid composition of atherosclerotic plaques is considered to be one of the primary indicators for plaque vulnerability, many IV-PA applications are calibrated so as to target plaque necrotic cores. Based on the mode of optical excitation and the corresponding signal processing technique, IV-PA is categorized into two different modalities. The pulse-based IV-PA has been the universal IV-PA imaging mode with its high peak power and straightforward time-domain signal processing technique. As an alternative, the low power continuous-wave (CW)-based IV-PA has been under intense development as a radar-like frequency-domain signal processing modality. The two state-of-the-art types of IV-PA are reviewed in terms of their physics and imaging capabilities, with major emphasis on frequency-swept CW-based IV-PA that has been recently introduced in the field.

This study investigated (a) the hypothesis that stroke patients with aortic atheroma would show comparable atherosclerotic changes in the carotid arteries, which are easily accessible for ultrasound evaluation and (b) the possibility of carotid duplex sonography as a replacement for transoesophageal echocardiography (TEE) for the exclusion or prediction of relevant aortic plaques.In 301 consecutive patients (mean age 62 years) with acute cerebral ischaemia, two dimensional ultrasound measurements were taken of common carotid artery intima media thickness (IMT) and maximal plaque area (PA) and the local degree of internal carotid artery (ICA) stenosis were determined. Maximal aortic wall thickness (AWT) was assessed by TEE.An IMTor =0.9 mm yielded a negative predictive value (NPV) of 95.8% for exclusion of aortic atheromasor =4 mm and an NPV of 100% for the exclusion of aortic thrombi. However, positive predictive value of IMT0.9 mm was low (29.6%), increasing only slightly in the presence of carotid plaques (33%). Incidence of aortic thrombi was significantly higher withor =50% compared with50% ICA stenosis (11.3% v 3.9%, respectively). IMT and PA correlated moderately with AWT (r = 0.47, r = 0.53, respectively; p0.001). Systolic blood pressure, coronary heart disease and peripheral artery disease, increased IMT, and ICA stenosisor =50% were independently related to AWTor =4 mm.A high NPV of normal carotid ultrasound does not support routine TEE for the exclusion of complex aortic plaques as a high risk source of cerebral embolism. However, in patients with carotid atherosclerosis, particularly in those with ICA stenosisor =50%, TEE should be performed to exclude an additional high risk source for stroke.

The literature concerning patent ductus arteriosus is briefly reviewed. A persistent patent ductus arteriosus may be eliminated by surgical division or ligation. When the duct remains open after the first year of life, spontaneous obliteration is not likely to occur. Unless associated with other cardiovascular anomalies, its surgical treatment in children over the age of four years should be considered in order that life expectancy may be increased. The surgical mortality in skilled hands is sufficiently low to justify this conclusion. Since recanalization has frequently followed ligation of a patent ductus arteriosus, division is considered the procedure of choice. A modified technic for division of a patent ductus arteriosus is presented. This technic is considered to have several advantages, being safer and more widely applicable than the technics now in use. Twelve cases are reported in which the diagnosis of patent ductus arteriosus was made and operation performed. In one case the preoperative diagnosis of patent ductus was in error. There was one surgical (anesthetic?) death. Other cases reported in detail include: one in which massive hemorrhage occurred following division of the duct and in which convalescence was complicated by the occurrence of pulmonary emboli; one in which the aorta was clamped for a total of thirty- five minutes while hemorrhage was being controlled and the duct divided; one case in which attacks resembling narcolepsy were apparently relieved following ligation of the duct; and one in which decortication of the lung was performed at the time of ductus ligation.