Transient Global Cerebral Hypoperfusion as a Characteristic Cerebral Hemodynamic Pattern in the Acute Stage after Combined Revascularization Surgery for Pediatric Moyamoya Disease: N-Isopropyl-P-[123I] Iodoamphetamine Single-Photon Emission Computed Tomography Study

<b><i>Introduction:</i></b> Surgical revascularization prevents cerebral ischemic attack by improving cerebral blood flow (CBF) in both adult and pediatric patients with moyamoya disease (MMD). Uneven hemodynamic changes, including local cerebral hyperperfusion and remote ischemia, can cause delayed intracerebral hemorrhage and perioperative infarctions in adult MMD patients, but the characteristic hemodynamic pattern among pediatric MMD patients after revascularization surgery is poorly understood. <b><i>Methods:</i></b> This study included 16 consecutive pediatric MMD patients (age, 6–16 years; mean age, 11.3) undergoing superficial temporal artery-middle cerebral artery anastomosis combined with encephalo-duro-myo-synangiosis on 21 affected hemispheres. Perioperative management was conducted by aspirin administration and strict blood pressure control (110–130 mm Hg). We prospectively performed N-isopropyl-p-[¹²³I] iodoamphetamine single-photon emission computed tomography on postoperative days (POD) 1 and 7 and analyzed the temporal changes in perioperative hemodynamics. <b><i>Results:</i></b> Four patients (19.0%, 4/21) exhibited immediate CBF improvement from POD 1, which was classified as “immediate redistribution pattern.” In contrast, 9 (42.9%, 9/21) demonstrated transient hemispheric global hypoperfusion at POD 1 and subsequent CBF improvement at POD 7, which was defined as “transient hypoperfusion pattern.” Although 8 patients, including 4 with “transient hypoperfusion pattern” (44.4, 4/9), developed mild transient neurological deterioration in the acute stage, it resolved in all 21 patients, and there were no permanent neurological deficits. <b><i>Discussion/Conclusions:</i></b> This study revealed that the “transient hypoperfusion pattern” after revascularization surgery is relatively common among pediatric MMD patients, and its outcome is favorable under strict perioperative management.

Hemodynamic Patterns of Spinal Cord Perfusion in Thoracoabdominal Aortic Aneurysm Repair

Paraplegia in aortic surgery is due to its impact on spinal cord perfusion whose hemodynamic patterns (SCPHP) are not clearly defined. Detailed morphological analysis of vascular network and collateral network modifications within Monro–Kellie postulate due to the fixed theca confines was performed to identify SCPHP. SCPHP may begin with intraspinal “backflow” (I-BF), that is, hemorrhage from anterior and posterior spinal arteries, backward via the connected anterior and posterior radicular medullary arteries, through the increasing diameter and decreasing resistance of segmental arteries (SAs), off their aortic orifices outside vascular network at 0 operative field pressure. The I-BF blood bypasses both intra- and extraspinal capillary networks and causes depressurization (0 diastolic pressure) and full ischemia of dependent spinal cord. When the occlusion of those SAs orifices arrests I-BF, the hemodynamic pattern of intraspinal “steal” (I-S) may take place. The formerly I-BF blood, in fact, is now variably shared between the fraction maintained in its physiological intraspinal network and that keeping flowing as I-S through the extraspinal capillary network. I-S is, however, counteracted by the extraspinal “steal” from the connected mammary/paraspinous-independent extraspinal feeders, all physically competing for the same room left by the missed physiological SA direct aortic blood inflow. Steal phenomenon evolves within the 120-hour time frame of CNm, whose intraspinal anatomical changes may offer the physical basis within the Monro–Kelly postulate, respectively of the intraoperative and postoperative paraplegia. The current procedures could not prevent the unphysiological SCPHP but awareness of details of their various features may offer the basis for improvements tailored, to the adopted intra- and postoperative procedures.

Transposition of Great Arteries

TGA is the commonest complex congenital cyanotic cardiac anomaly occurring during the first week of life. It is characterized by the unusual anomaly of ventriculoarterial discordance, with the aorta (A) originating from the right ventricle (RV) and the pulmonary artery (PA) from the left ventricle (LV). In the common Dextro form (DTGA), A is abnormally located to the right, anterior, and inferior of PA. The anatomic configuration results in the lethal hemodynamic pattern of 2 independent and parallel running circulatory circuits, which mandates creating a conduit to ensure the mixing of oxygenated and deoxygenated blood for survival. In the rare Levo form (LTGA), the aorta is placed anterior and to the left of PA with ventricular inversion. TGA is well tolerated in the fetus and is challenging to diagnose by fetal echocardiography unless the outflow tracts are specifically visualized. Postnatally the typical findings of murmur and cyanosis vary according to the associated cardiac defects and the degree of intercirculatory mixing. The arterial switch operation (ASO), which involves establishing ventriculoarterial concordance, is the standard surgical repair of D-TGA and has replaced the atrial switch procedures due to its superior long-term outcomes. The Rastelli procedure is used for complex DTGA cases. DTGA has a 90% mortality rate in the first year of life if untreated, while over 95% survive for 5 to 25 years after surgery. Post-surgical course may be complicated and require surgical revisions. The long-term outcome is associated with normal or mild to moderate neurodevelopmental disabilities, depending upon the type, complexity, and course of the disease. Expert follow-up of the patients into adulthood is an integral part of the management of TGA for best outcomes.

Hemodynamic Response to Three Types of Urban Spaces before and after Lockdown during the COVID-19 Pandemic

(1) Background: Prolonged lockdowns with stay-at-home orders have been introduced in many countries since the outbreak of the COVID-19 pandemic. They have caused a drastic change in the everyday lives of people living in urbanized areas, and are considered to contribute to a modified perception of the public space. As research related to the impact of COVID-19 restrictions on mental health and well-being emerges, the associated longitudinal changes of brain hemodynamics in healthy adults remain largely unknown. (2) Methods: this study examined the hemodynamic activation patterns of the prefrontal and occipital cortices of 12 participants (5 male, Mage = 47.80, SDage = 17.79, range 25 to 74, and 7 female, Mage = 39.00, SDage = 18.18, range 21 to 65) passively viewing videos from three urban sites in Singapore (Urban Park, Neighborhood Landscape and City Center) at two different time points—T1, before the COVID-19 pandemic and T2, soon after the lockdown was over. (3) Results: We observed a significant and marginally significant decrease in average oxyhemoglobin (Oxy-Hb) over time for each of the visual conditions. For both green spaces (Urban Park and Neighborhood Landscape), the decrease was in the visual cortex, while for the City Center with no green elements, the marginal decrease was observed in the visual cortex and the frontal eye fields. (4) Conclusions: The results suggest that the COVID-19-related lockdown experienced by urban inhabitants may have contributed to decreased brain hemodynamics, which are further related to a heightened risk of mental health disorders, such as depression or a decline in cognitive functions. Moreover, the busy City Center scenes induced a hemodynamic pattern associated with stress and anxiety, while urban green spaces did not cause such an effect. Urban green scenes can be an important factor to offset the negative neuropsychological impact of busy urban environments post-pandemic.

Pulsed-wave doppler ultrasound in canine reproductive system – Part 1: technical aspects

The purpose of this article is to review the literature on the essential technical aspects of implementing the pulsed Doppler, as part of the teachings to their use in the diagnosis of changes in the canine reproductive system. A narrative review was carried out, using scientific articles, monographs, theses and dissertations published and available in online databases: Periodical Capes (Coordination for the Improvement of Higher Education Personnel), SciELO (Scientific Electronic Library Online) and Google Scholar, in addition to specific books on the topic. Two-dimensional ultrasound has been widely used in medicine since 1942, leading to advancements in disease identification and subsequent prognosis. In terms of vascular assessment, Doppler ultrasound is used to evaluate the blood flow inside the vessel, its direction, and hemodynamic pattern. Among all types of Doppler ultrasound, the Color Doppler (CD), Power Doppler (PD), and the Pulsed-wave Doppler (PW) are commonly used in the identification of abnormalities through ultrasound flow imaging and the analysis of hemodynamic indices: peak systolic velocity (PSV), end diastolic velocity (EDV), resistance index (RI), and pulsatility index (PI). To accurately estimate these hemodynamic indices, however, it is essential to know the technical adjustments and parameters such as the pulse repetition frequency (PRF), size of the sample volume (Gate), angle of insonation, gain, baseline, and wall filter, which need to be corrected to avoid technician derive artifacts such as aliasing, signal absence, and mirror imaging. In medicine, the use of Doppler Mode in reproductive functions is already well established, but its use in veterinary medicine is still a subject of recent studies.

Differences in Penile Hemodynamic Profiles in Patients with Erectile Dysfunction and Anxiety

Background: Penile echo-color Doppler ultrasound (PCDU) is the gold standard for the diagnosis of arterial erectile dysfunction (ED). Its reliability in patients with anxiety was questioned, due to false-positive results. Aim: To assess the penile hemodynamic response to intracavernous injection (ICI) of alprostadil in patients with anxiety-related ED. Methods: Patients with non-organic ED and a 5-item International Index of Erectile Function (IIEF-5) score ranging between 5 and 7 were enrolled. They were asked to compile the 7-item Generalized Anxiety Disorder (GAD-7) questionnaire to assess the degree of anxiety and were divided according to the GAD-7 score in Group 1 with minimal level of anxiety (n = 20), Group 2 with mild anxiety (n = 20), Group 3 with moderate anxiety (n = 20), and Group 4 with severe anxiety (n = 20). Peak systolic velocity (PSV) and the end-diastolic velocity (EDV) were sampled in all patients, through PCDU in the flaccid state, and 5, 10, 15, and 20 min after ICI of alprostadil at the standard dose of 10 μg. Results: In penile flaccidity, the patients showed a mean PSV of 8.0 ± 4.0 cm/s. The degree of anxiety was found to significantly influence both PSV and EDV at all assessed time-points. Particularly, it was negatively associated with the PSV at time 5 (r = −0.9, p < 0.01), 10 (r = −0.9, p < 0.01), 15 (r = −0.9, p < 0.01), and 20 (r = −0.7, p < 0.01) minutes, and positively with the EDV at time 5 (r = 0.7, p < 0.01), 10 (r = 0.6, p < 0.01), 15 (r = 0.5, p < 0.01), and 20 (r = 0.3, p < 0.01) minutes. Although all patients showed a mean dynamic PSV > 25 cm/s (which excluded an arterial ED according to the current guidelines), a peculiar hemodynamic pattern was found in patients with severe anxiety. In these patients, normal PSV values were reached only after 20 min from ICI, suggesting a “late-responder” profile. Conclusion: If further studies confirm the existence of a distinct hemodynamic profile in patients with severe anxiety, sampling the PSV and the EDV values could be proposed, for detecting patients with severe anxiety-related ED. Dynamic PCDU could be considered an accurate diagnostic test in patients with non-organic ED, since zero false-positive results were found in the present study. PSV in the flaccid state is not able to discriminate between arterial- or non-organic ED.

FEATURES OF HEMODYNAMICS IN HEAD MAGISTRAL AND CEREBRAL ARTERIES IN THE PATIENTS WITH MIGRAINE

The aim of the study was to Doppler sonography study of the structural and functional state of head magistral arteries (HMA) and cerebral arteries in the patients with various forms of migraine. Materials and methods: We conducted the clinical Doppler examination of 124 young patients (18-45 years old), including 55 men and 69 women in the conditions of the clinical base of the Kharkiv Medical Academy of Postgraduate Education in 2017-2019. The criteria for involvement of patients in the study were: migraine without aura (group 1 – 63 patients), migraine with aura (group 2 – 61 patients) The control group consisted of 45 patients of the corresponding gender and age. The condition of HMA and cerebral arteries was studied using the ultrasound device. Results: The presence of extravasal compressions of vertebral arteries (VA) is typical for the patients with migraine, as well as for some cases of the hypoplasia of the VA in the group of the patients with migraine with aura. In the patients with migraine with aura, there was a decrease in the velocity values in the extracranial VA segments. The velocity values in the external carotid arteries (ECA) were slightly reduced in both groups. The most significant were the changes in the hemodynamics in the middle cerebral arteries (MCA), which were manifested by the pattern of the excessive perfusion in the patients of the migraine without aura and the pattern of the hampered perfusion in the MCA in the patients of the migraine with aura. Conclusions: 1. In the patients with migraine with aura, a decrease in the velocity values in the extracranial segments of the VA was observed, in some cases combined with the hypoplasia of the vertebral artery, the hampered perfusion in middle cerebral arteries. 2. The excessive perfusion in middle cerebral arteries is the most critical hemodynamic pattern in the patients with migraine without aura. 3. The extravasal compression of vertebral arteries, combined with the hyperperfusion in posterior cerebral arteries, is a typical hemodynamic pattern both in the group of the patients with migraine with aura, and in the group of the patients with migraine without aura.

Pulmonary hypertension or cardiology aerobatics

Pulmonary hypertension (PH) is a group of diseases with a hemodynamic pattern of progressive increase in pulmonary vascular resistance (PVR) and pulmonary artery pressure (PAP), which leads to right ventricular dysfunction and the development of right ventricular heart failure.

Relationship between aortic valve stenosis and the hemodynamic pattern in the renal circulation, and restoration of the flow wave profile after correction of the valvular defect

Objective The index of maximal systolic acceleration ([AImax]: maximal systolic acceleration of the Doppler waveform divided by peak systolic velocity) shows diagnostic accuracy in screening of renal artery stenosis. This study aimed to determine whether an upstream factor of resistance, such as aortic valve stenosis (AVS), can affect Doppler parameters detected in the peripheral arteries. Methods In this prospective study, we measured the AImax in non-stenotic renal interlobar arteries of 62 patients with AVS. Patients were divided into three groups on the basis of severity of valvulopathy as follows: mild-to-moderate AVS (M-AVS; n = 24), intermediate AVS (I-AVS; n = 15), and severe AVS (S-AVS; n = 23) based on Nishimura’s criteria. Results The AImax in the renal parenchymal arteries was significantly lower in the S-AVS group (8.9 ± 3.6 s−1) than in the M-AVS (15.3 ± 3.8 s−1) and I-AVS groups (16.7 ± 5.2 s−1). The AImax was positively correlated with the aortic valve area and inversely correlated with the tranvalvular aortic pressure gradient. After aortic valve replacement, the AImax significantly increased from 10.7 ± 4.0 s−1 at baseline to 19.3 ± 4.4 s−1. Conclusions Proximal resistance can lead to diagnostic bias of Doppler parameters that are applied in the diagnosis of peripheral vasculopathies, particularly in renal artery stenosis.

ESTIMATION OF WALL SHEAR STRESS OF COMPLIANT THORACIC AORTA WITH ANEURYSM

In this paper, a numerical estimation of wall shear stress (WSS) in a compliant Thoracic Aorta (TA) with aneurysm is modeled and the hemodynamic pattern is studied using Computational Fluid Dynamics (CFD). Thoracic Aortic Aneurysm (TAA) is an excessively localized enlargement of TA caused by weakness in the arterial wall and it can rupture the inner wall intima and continue on to the outer wall adventitia. WSS is a tangential force exerted by blood flow on the vessel wall, and its estimation is clinically very important because any change in WSS is considered as a vital cue in the onset of aneurysm. In this work, a three-dimensional (3D) model of a TAA reconstructed from computed tomography (CT) images comprising of 600 slices with 1-mm resolution from neck to hip is considered and patient-specific simulations have been carried out in compliant TA under rest and exercise conditions. The findings show that the change in wall geometry was marginal due to variation in pressure forces inside and is not the primary source for expansion of an aneurysm. It was inferred that expansion was rather due to thinning of the wall, owing to damage caused to the inner lining of the tissues, at regions of high WSS. It was found that the geometry extraction is important as any change in length causes a corresponding variation in mass flow through it. Although mass conservation is maintained irrespective of the length, it does affect the rate of flow due to shifting in the pressure boundary conditions with the length as it varies the pressure inside the system. Modeling of the geometry is very important as the change in mass flow will affect the outlet velocity and strength of vortices. Surprisingly, the split-up of flow is consistent but the geometric change in the model has no effect on WSS values and flow pattern. The results of this study provide important information such as blood flow pattern and pressure drops in the compliant TA on WSS estimations with TAA diseases.