Cerebral Pulsatility Index Is Elevated in Patients with Elevated Right Atrial Pressure

Intracranial Pressure and Cerebral Hemodynamics in Infants Before and After Glenn Procedure

OBJECTIVES

This prospective cohort study aimed to investigate changes in intracranial pressure (ICP) and cerebral hemodynamics in infants with congenital heart disease undergoing the Glenn procedure, focusing on the relationship between superior vena cava pressure and estimated ICP.

DESIGN

A single-center prospective cohort study.

SETTING

The study was conducted in a cardiac center over 4 years (2019-2022).

PATIENTS

Twenty-seven infants with congenital heart disease scheduled for the Glenn procedure were included in the study, and detailed patient demographics and primary diagnoses were recorded.

INTERVENTIONS

Transcranial Doppler (TCD) ultrasound examinations were performed at three time points: baseline (preoperatively), postoperative while ventilated (within 24-48 hr), and at discharge. TCD parameters, blood pressure, and pulmonary artery pressure were measured.

MEASUREMENTS AND MAIN RESULTS

TCD parameters included systolic flow velocity, diastolic flow velocity (dFV), mean flow velocity (mFV), pulsatility index (PI), and resistance index. Estimated ICP and cerebral perfusion pressure (CPP) were calculated using established formulas. There was a significant postoperative increase in estimated ICP from 11 mm Hg (interquartile range [IQR], 10-16 mm Hg) to 15 mm Hg (IQR, 12-21 mm Hg) postoperatively (p = 0.002) with a trend toward higher CPP from 22 mm Hg (IQR, 14-30 mm Hg) to 28 mm Hg (IQR, 22-38 mm Hg) postoperatively (p = 0.1). TCD indices reflected alterations in cerebral hemodynamics, including decreased dFV and mFV and increased PI. Intracranial hemodynamics while on positive airway pressure and after extubation were similar.

CONCLUSIONS

Glenn procedure substantially increases estimated ICP while showing a trend toward higher CPP. These findings underscore the intricate interaction between venous pressure and cerebral hemodynamics in infants undergoing the Glenn procedure. They also highlight the remarkable complexity of cerebrovascular autoregulation in maintaining stable brain perfusion under these circumstances.

Pulsatility analysis of the circle of Willis

Purpose

To evaluate the phenomenological significance of cerebral blood pulsatility imaging in aging research.

Methods

N = 38 subjects from 20 to 72 years of age (24 females) were imaged with ultrafast MRI with a sampling rate of 100 ms and simultaneous acquisition of pulse oximetry data. Of these, 28 subjects had acceptable MRI and pulse data, with 16 subjects between 20 and 28 years of age, and 12 subjects between 61 and 72 years of age. Pulse amplitude in the circle of Willis was assessed with the recently developed method of analytic phase projection to extract blood volume waveforms.

Results

Arteries in the circle of Willis showed pulsatility in the MRI for both the young and old age groups. Pulse amplitude in the circle of Willis significantly increased with age (p = 0.01) but was independent of gender, heart rate, and head motion during MRI.

Discussion and conclusion

Increased pulse wave amplitude in the circle of Willis in the elderly suggests a phenomenological significance of cerebral blood pulsatility imaging in aging research. The physiologic origin of increased pulse amplitude (increased pulse pressure vs. change in arterial morphology vs. re-shaping of pulse waveforms caused by the heart, and possible interaction with cerebrospinal fluid pulsatility) requires further investigation.

Hypertension Correlates With Stronger Blood Flow Pulsatility in Small Perforating Cerebral Arteries Assessed With 7 Tesla Magnetic Resonance Imaging

BACKGROUND

Hypertension alters the structure and function of cerebral blood vessels, and is an important risk factor for stroke and cerebral small vessel disease (cSVD). However, the pathophysiological process is not yet well understood. This study aimed to investigate the relationship between the pulsatility measures in small perforating arteries and hypertension, since hypertension-induced arterial stiffening may lead to a higher blood flow pulsatility and lower damping.

METHODS

We examined 28 patients with essential hypertension and 25 age- and sex-matched healthy controls (mean age: 63.4, range: 43-81 years, 26 males). Blood flow velocity waveforms were acquired in the lenticulostriate arteries (LSAs) and the middle cerebral artery using phase-contrast MRI at 7 Tesla. Several cSVD markers were scored. The velocity and pulsatility measures were compared between the hypertensives and controls.

RESULTS

A higher pulsatility index (PI) in the LSAs and a lower damping factor (DF) was found in the hypertensive compared to the normotensive group (P=0.015, P=0.015, respectively), but no association was found for the PI in the middle cerebral artery. Higher systolic and mean arterial pressures were associated with higher PI in the LSA and DF. For diastolic blood pressure, only an association with a lower DF was found. Adjusting for cSVD score did not alter these relationships.

CONCLUSIONS

This study shows a higher PI in the LSAs and a lower DF in subjects with hypertension, independent of cSVD presence. This supports the hypothesis that hypertension-induced arterial remodeling may alter the intracerebral blood flow velocity profiles, which could eventually contribute to cerebral tissue damage.

REGISTRATION

URL: https://trialsearch.who.int/; Unique identifier: NL7537 and NL8798.

Echocardiographic correlates of MRI imaging markers of cerebral small-vessel disease in patients with atrial-fibrillation-related ischemic stroke

Background and objectives

Atrial fibrillation (AF) has been linked to dementia risk, partly explained by cerebral small vessel disease (CSVD). Since AF and cardiovascular comorbidities were associated with cardiac dysfunction, we aimed to determine the association between echocardiographic parameters and neuroimaging markers of CSVD in patients with AF-related ischemic stroke.

Methods

This cross-sectional study enrolled patients with AF-related ischemic stroke from March 2013 to December 2019 who underwent transthoracic echocardiography and brain 3T MRI, including T1, T2, Flair, and SWI imaging sequences. We assessed the presence of lacunes and cerebellar microbleeds (CMBs), the severity of white matter hyperintensity (WMH) scored by the Fazekas scale (0-6), and the severity of enlarged perivascular spaces (EPVS) in basal ganglia (BG) and centrum semiovale (CSO) classified into three categories (0-10, 10-25, and >25). CSVD burden was rated on a 0-to-4 ordinal scale. Generalized linear regression analysis and post hoc comparisons with Bonferroni correction were performed to assess the association between various echocardiographic parameters and these lesions, adjusted for demographics and potential confounders.

Results

119 patients (68.38 ± 12.692 years; male 45.4 %) were included for analysis, of whom 55 (46.2%) had lacunes, 40 (33.6%) had CMBs, and median severity for WMH, BG-EPVS, CSO-EPVS, and CSVD burden were 2 (IQR: 1-3), 1 (IQR: 1-2), 1 (IQR: 0-1), and 1 (IQR: 1-2) respectively. In multivariable, fully adjusted models, left ventricular posterior wall thickness (LVPW) was associated with a higher risk of lacunes (RR 1.899, 95% CI: 1.342-2.686) and CSVD burden (RR = 2.081, 95%CI: 1.562-2.070). Right atrial diameter (RAD) was associated with greater CSO-EPVS (RR = 2.243, 95%CI: 1.234-4.075). No echocardiographic parameters were revealed to be associated with CMBs and WMH.

Conclusion

In patients with AF-related ischemic stroke, LVPW is associated with a higher risk of lacunes and CSVD burden, while RAD was associated with greater CSO-EPVS. Larger studies are required to determine these associations and to elucidate if these associations can help facilitate cognitive evaluation and brain MRI screening.

Left ventricular ejection fraction and right atrial diameter are associated with deep regional CBF in arteriosclerotic cerebral small vessel disease

Background

Systemic cardiac hypoperfusion is a well-acknowledged contributor to ischemic leukoencephalopathy. However, it has remained elusive how atherosclerosis-mediated cardiac remodelling modifies cerebral perfusion homeostasis as well as neuroimaging burden in cerebral small vessel disease (CSVD) development.

Methods

This retrospective study identified 103 arteriosclerotic CSVD (aCSVD) patients (CSVD burden^low 0 ~ 1, n = 61 and CSVD burden^high 2 ~ 4, n = 42) from Sep. 2017 to Dec. 2019 who underwent transthoracic echocardiography(n = 81), structural magnetic resonance imaging and arterial spin labelling (ASL). Total CSVD burden was graded according to the ordinal “small vessel disease” rating score (0–4). We investigated the univariate and multivariate linear regression of mean deep regional cerebral blood flow (CBF) as well as logistic regression analysis of CSVD burden^high.

Results

Right atrial diameter (B coefficient, − 0.289; 95% CI, − 0.578 to − 0.001; P = 0.049) and left ventricular ejection fraction (B coefficient, 32.555; 95% CI, 7.399 to 57.711; P = 0.012) were independently associated with deep regional CBF in aCSVD patients. Binary logistic regression analysis demonstrated decreased deep regional CBF (OR 0.894; 95% CI 0.811–0.985; P = 0.024) was independently associated with higher CSVD burden after adjusted for clinical confounders. Multivariate receiver operating characteristics curve integrating clinical risk factors, mean deep CBF and echocardiographic parameters showed predictive significance for CSVD burden^high diagnosis (area under curve = 84.25, 95% CI 74.86–93.65%, P < 0.0001).

Conclusion

The interrelationship of “cardiac -deep regional CBF-neuroimaging burden” reinforces the importance and prognostic significance of echocardiographic and cerebral hemodynamic assessment in CSVD early-warning.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12883-021-02096-w.

A proposed algorithm for combining transcranial Doppler ultrasound monitoring with cerebral and somatic oximetry: a case report

PURPOSE

Transcranial Doppler (TCD) ultrasound is a non-invasive monitor of cerebral blood velocity that can be used intraoperatively. The purpose of this report is to describe how different patterns seen on TCD can help identify the cause of cerebral desaturation when near-infrared spectroscopy (NIRS) oximetry is used concomitantly.

CLINICAL FEATURES

A 69-yr-old male patient undergoing coronary revascularisation and aortic valve replacement developed perioperative complications that were detected using a combination of transtemporal TCD of the middle cerebral artery along with cerebral and somatic NIRS. Initial brain desaturation was secondary to hypocapnia during which TCD-derived blood velocity and somatic NIRS values remained unchanged. After the procedure, a second episode of brain desaturation occurred secondary to a technical issue with the aortic valve prosthesis requiring a return to cardiopulmonary bypass (CPB); there were no high-intensity transient signals (HITS) on TCD. Brain desaturation occurred a third time following the second attempt to separate from CPB at which time TCD detected a significant amount of HITS suggesting air emboli that were associated with acute right ventricular dysfunction; there was also a reduction in somatic NIRS.

CONCLUSIONS

Combining TCD with cerebral NIRS allows for the rapid identification of three different mechanisms of brain desaturation. An algorithm is proposed to help identify the origin of NIRS cerebral desaturation. Prospective clinical trials are needed to investigate potential benefits of multimodal brain monitoring and its impact on short and/or long-term clinical outcomes.

Clinical and Technical Limitations of Cerebral and Somatic Near-Infrared Spectroscopy as an Oxygenation Monitor

Cerebral and somatic near-infrared spectroscopy monitors are commonly used to detect tissue oxygenation in various circumstances. This form of monitoring is based on tissue infrared absorption and can be influenced by several physiological and non-physiological factors that can induce error in the interpretation. This narrative review explores those clinical and technical limitations and proposes solutions and alternatives in order to avoid some of those pitfalls.