Transcranial Doppler assessment of cerebral blood flow: effect of cardiac transplantation

Congestive heart failure and its associations with cognition and cerebral blood flow

BACKGROUND

Congestive heart failure (CHF) has been linked to dementia but for reasons not well understood. Our retrospective cohort study aims to determine if specific measures of CHF severity are associated with cognitive performance or cerebral blood flow velocity (CBFV) among decompensated CHF outpatients.

MATERIALS AND METHODS

One hundred and thirty-eight patients with transthoracic echocardiogram ≤1-year preceding consent were included. Forty-nine patients had concurrent transcranial Doppler ultrasonography administered by a trained technician assessing anterior cerebral artery, middle cerebral artery, and internal carotid artery (ICA) CBFV. CHF characteristics considered were NYHA classification, CHF type (heart failure with preserved ejection fraction vs. heart failure with mildly reduced/reduced ejection fraction), and left ventricular ejection fraction (LVEF; continuous [per 5%] or categorized [≤40%, 40%-55%, and ≥55%]). A trained psychometrist administered a standardized cognitive battery including Rey Auditory Verbal Learning Test, Rey Complex Figure Copy and Immediate Recall test, Letter-Number Sequencing (LNS) test, and Trail Making Tests. Adjusted multivariable linear regression models determined the association between CHF characteristics and standardized cognitive tests as well as between CHF characteristics and standardized CBFV, in distinct models.

RESULTS

On average, NYHA Class 1-2 patients had better LNS scores than NYHA Class 3-4 patients (β: 0.47; 95% CI: 0.09, 0.84). Patients with LVEF 40%-55% had higher ICA CBFVs than those with LVEF ≤40% (β: 13.7; 95% CI: 1.01, 26.39). No associations between other CHF characteristics and either cognitive performance or CBFV were found.

CONCLUSION

Blood flow may be an important mechanism behind CHF-related cognitive decline, but studies with larger sample sizes and a control group without CHF are needed.

Treating Aortic Valve Stenosis for Vitality Improvement: The TAVI Study

BACKGROUND

Degenerative aortic valve stenosis (AS) is the most common valvular heart disease among the elderly. Once cardiac symptoms occur, current guidelines recommend aortic valve replacement. Progressive degeneration/calcification reduces leaflet mobility with gradual cardiac output (CO) impairment. Low CO might induce abnormal brain-aging with cognitive impairment and increased risk of dementia, such as Alzheimer's disease or vascular dementia. On the contrary, cognitive improvement has been reported in patients in whom CO was restored. Transcatheter aortic valve implantation (TAVI) has proven to be a safe alternative to conventional surgery, with a similar mid-term survival and stroke risk even in low-risk patients. TAVI is associated with an immediate CO improvement, also effecting the cerebrovascular system, leading to an increased cerebral blood flow. The correlation between TAVI and cognitive improvement is still debated. The present study aims at evaluating this relationship in a cohort of AS patients where cognitive assessment before and after TAVI was available.

METHODS

a total of 47 patients were retrospectively selected. A transcranial Doppler ultrasound (TCD) before and after TAVI, a quality of life (QoL) score, as well as a mini-mental state examination (MMSE) at baseline and up to 36 months, were available.

RESULTS

TAVI was associated with immediate increase in mean cerebral flow at TCD. MMSE slowly increase at 36-months follow-up with improved QoL mainly for symptoms, emotions and social interactions.

CONCLUSIONS

this proof-of-concept study indicates that TAVI might induce cognitive improvement in the long-term as a result of multiple factors, such as cerebral flow restoration and a better QoL.

Septal E/e' Ratio Is Associated With Cerebral White Matter Hyperintensity Progression in Young-Old Hypertensive Patients

Background: The incidence of hypertension increases with age, as does that of brain abnormalities associated with cerebral pathologic and functional degeneration. Little is known about the relationship between hypertension-related cardiac changes and cerebral pathologic degeneration. We examined the relationship between left ventricular (LV) diastolic dysfunction and cerebral white matter hyperintensity (WMH) progression in young-old hypertensive patients. Methods and Results: This single-center prospective longitudinal observational study included 156 individuals aged 65-75 years with well-controlled hypertension, normal LV contraction, and no history of symptomatic heart failure. WMH was quantified on brain magnetic resonance imaging (MRI). The primary outcome was the rate of WMH volume progression between the baseline and follow-up MRI (∆WMH). Participants were classified into tertiles on the basis of ∆WMH (small, medium, and large ∆WMH). The mean (±SD) age at recruitment was 69.6±2.8 years, and the mean follow-up period was 4.6 years. The ratio of early diastolic mitral inflow velocity to early diastolic septal mitral annulus velocity (septal E/e') was significantly higher in the large ∆WMH group than in the small and medium ∆WMH groups. On multiple regression analysis, septal E/e' was significantly positively associated with square-root-transformed ∆WMH (β=0.457, P<0.001). Conclusions: Septal E/e' was significantly positively associated with the rate of progression of WMH volume, suggesting that LV diastolic dysfunction is associated with the progression of abnormal brain aging.

Hemorrhagic Cerebral Insults and Secondary Takotsubo Syndrome: Findings in a Novel In Vitro Model Using Human Blood Samples

Intracranial hemorrhage results in devastating forms of cerebral damage. Frequently, these results also present with cardiac dysfunction ranging from ECG changes to Takotsubo syndrome (TTS). This suggests that intracranial bleeding due to subarachnoid hemorrhage (SAH) disrupts the neuro-cardiac axis leading to neurogenic stress cardiomyopathy (NSC) of different degrees. Following this notion, SAH and secondary TTS could be directly linked, thus contributing to poor outcomes. We set out to test if blood circulation is the driver of the brain-heart axis by investigating serum samples of TTS patients. We present a novel in vitro model combining SAH and secondary TTS to mimic the effects of blood or serum, respectively, on blood-brain barrier (BBB) integrity using in vitro monolayers of an established murine model. We consistently demonstrated decreased monolayer integrity and confirmed reduced Claudin-5 and Occludin levels by RT-qPCR and Western blot and morphological reorganization of actin filaments in endothelial cells. Both tight junction proteins show a time-dependent reduction. Our findings highlight a faster and more prominent disintegration of BBB in the presence of TTS and support the importance of the bloodstream as a causal link between intracerebral bleeding and cardiac dysfunction. This may represent potential targets for future therapeutic inventions in SAH and TTS.

Cardiac Output and Cerebral Blood Flow: A Systematic Review of Cardio-Cerebral Coupling

Control of cerebral blood flow (CBF) is crucial to the management of neurocritically ill patients. Small studies which have examined the role of cardiac output (CO) as a determinant of CBF have inconsistently demonstrated evidence of cardio-cerebral coupling. Putative physiological mechanisms underpinning such coupling include changes in arterial blood pressure pulsatility, which would produce vasodilation through increased oscillatory wall-shear-stress and baroreceptor mediated reflex sympatholysis, and changes in venous backpressure which may improve cerebral perfusion pressure. We sought to summarize and contextualize the literature on the relationship between CO and CBF and discuss the implications of cardio-cerebral coupling for neurocritical care. A systematic review of the literature yielded 41 studies; all were of low-quality and at high-risk of bias. Results were heterogenous, with evidence for both corroboration and confutation of a relationship between CO and CBF in both normal and abnormal cerebrovascular states. Common limitations of studies were lack of instantaneous CBF measures with reliance on transcranial Doppler-derived blood flow velocity as a surrogate, inability to control for fluctuations in established determinants of CBF (eg, PaCO2), and direct effects on CBF by the interventions used to alter CO. Currently, the literature is insufficiently robust to confirm an independent relationship between CO and CBF. Hypothetically, the presence of cardio-cerebral coupling would have important implications for clinical practice. Manipulation of CBF could occur without the risks associated with extremes of arterial pressure, potentially improving therapy for those with cerebral ischemia of various etiologies. However, current literature is insufficiently robust to confirm an independent relationship between CO and CBF, and further studies with improved methodology are required before therapeutic interventions can be based on cardio-cerebral coupling.

Neurological complications of heart failure

Heart failure (HF) is a major global cause of death with increasing absolute worldwide numbers of HF patients. HF results from the interaction between cardiovascular aging with specific risk factors, comorbidities, and disease modifiers. The failing heart and neuronal injury have a bidirectional interaction requiring specific management strategies. Decreased cardiac output has been associated with lower brain volumes. Cerebral blood flow (CBF) may normalize following heart transplantation among severe HF patients. Stroke and cognitive impairment remain the main neurologic conditions associated with HF. However, HF patients may also suffer from chronic cerebral hypoperfusion. It seems likely that HF-related ischemic strokes are primarily the result of cardiac embolism. Atrial fibrillation (AF) is present in half of stroke patient with HF. The increased risk of hemorrhagic strokes is less well characterized and likely multifactorial, but may in part reflect a higher use of long-term antithrombotic therapy. The steady improvement of neuroimaging techniques has demonstrated an increased prevalence of silent ischemic lesions among HF patients. The populations most likely to benefit from long-term anticoagulant therapy are HF patients with AF. Cognitive impairment in HF can have a variety of clinical manifestations from mild memory problems to dementia.

Correlation of cardiac function and cerebral perfusion in a murine model of subarachnoid hemorrhage

Cerebral hypoperfusion is a key factor for determining the outcome after subarachnoid hemorrhage (SAH). A subset of SAH patients develop neurogenic stress cardiomyopathy (NSC), but it is unclear to what extent cerebral hypoperfusion is influenced by cardiac dysfunction after SAH. The aims of this study were to examine the association between cardiac function and cerebral perfusion in a murine model of SAH and to identify electrocardiographic and echocardiographic signs indicative of NSC. We quantified cortical perfusion by laser SPECKLE contrast imaging, and myocardial function by serial high-frequency ultrasound imaging, for up to 7 days after experimental SAH induction in mice by endovascular filament perforation. Cortical perfusion decreased significantly whereas cardiac output and left ventricular ejection fraction increased significantly shortly post-SAH. Transient pathological ECG and echocardiographic abnormalities, indicating NSC (right bundle branch block, reduced left ventricular contractility), were observed up to 3 h post-SAH in a subset of model animals. Cerebral perfusion improved over time after SAH and correlated significantly with left ventricular end-diastolic volume at 3, 24, and 72 h. The murine SAH model is appropriate to experimentally investigate NSC. We conclude that in addition to cerebrovascular dysfunction, cardiac dysfunction may significantly influence cerebral perfusion, with LVEDV presenting a potential parameter for risk stratification.

Associations between left ventricular function, vascular function and measures of cerebral small vessel disease: a cross-sectional magnetic resonance imaging study of the UK Biobank

OBJECTIVES

Impaired cardiovascular function has been associated with cognitive deterioration; however, to what extent cardiovascular dysfunction plays a role in structural cerebral changes remains unclear. We studied whether vascular and left ventricular (LV) functions are associated with measures of cerebral small vessel disease (cSVD) in the middle-aged general population.

METHODS

In this cross-sectional analysis of the UK Biobank, 4366 participants (54% female, mean age 61 years) underwent magnetic resonance imaging to assess LV function (ejection fraction [EF] and cardiac index [CI]) and cSVD measures (total brain volume, grey and white matter volumes, hippocampal volume and white matter hyperintensities [WMH]). Augmentation index (AIx) was used as a measure of arterial stiffness. Linear and non-linear associations were evaluated using cardiovascular function measures as determinants and cSVD measures as outcomes.

RESULTS

EF was non-linearly associated with total brain volume and grey matter volume, with the largest brain volume for an EF between 55 and 60% (both p < 0.001). EF showed a negative linear association with WMH (- 0.23% [- 0.44; - 0.02], p = 0.03), yet no associations were found with white matter or hippocampal volume. CI showed a positive linear association with white matter (β 3194 mm³ [760; 5627], p = 0.01) and hippocampal volume (β 72.5 mm³ [23.0; 122.0], p = 0.004). No associations were found for CI with total brain volume, grey matter volume or WMH. No significant associations were found between AIx and cSVD measures.

CONCLUSIONS

This study provides novel insights into the complex associations between the heart and the brain, which could potentially guide early interventions aimed at improving cardiovascular function and the prevention of cSVD.

KEY POINTS

• Ejection fraction is non-linearly and cardiac index is linearly associated with MRI-derived measures of cerebral small vessel disease. • No associations were found for arterial stiffness with cSVD measures.

Cardiorespiratory Fitness Mediates Cognitive Performance in Chronic Heart Failure Patients and Heart Transplant Recipients

We compared cognitive profiles in chronic heart failure patients (HF), heart transplant recipients (HT) and healthy controls (HC) and examined the relationship between cardiorespiratory fitness (V˙O_2peak), peak cardiac output (CO_peak) and cognitive performance. Stable HT patients (n = 11), HF patients (n = 11) and HC (n = 13) (61.5 ± 8.5 years) were recruited. Four cognitive composite scores targeting different cognitive functions were computed from neuropsychological tests: working memory, processing speed, executive functions and verbal memory. Processing speed and executive function scores were higher, which indicates lower performances in HF and HT compared to HC (p < 0.05). V˙O_2peak and first ventilatory threshold (VT₁) were lower in HF and HT vs. HC (p < 0.01). CO_peak was lower in HF vs. HT and HC (p < 0.01). Processing speed, executive function and verbal memory performances were correlated with V˙O_2peak, VT₁ and peak cardiac hemodynamics (p < 0.05). Mediation analyses showed that V˙O_2peak and VT₁ mediated the relationship between group and processing speed and executive function performances in HF and HT. CO_peak fully mediated executive function and processing speed performances in HF only. V˙O_2peak and CO_peak were related to cognitive performance in the entire sample. In addition, V˙O_2peak and VT₁ fully mediated the relationship between group and executive function and processing speed performances.

Cerebral Blood Flow in Patients with Severe Aortic Valve Stenosis Undergoing Transcatheter Aortic Valve Implantation

BACKGROUND

Transcatheter aortic valve implantation (TAVI) is a minimally invasive, life‐saving treatment for patients with severe aortic valve stenosis that improves quality of life. We examined cardiac output and cerebral blood flow in patients undergoing TAVI to test the hypothesis that improved cardiac output after TAVI is associated with an increase in cerebral blood flow.

DESIGN

Prospective cohort study.

SETTING

European high‐volume tertiary multidisciplinary cardiac care.

PARTICIPANTS

Thirty‐one patients (78.3 ± 4.6 years; 61% female) with severe symptomatic aortic valve stenosis.

MEASUREMENTS

Noninvasive prospective assessment of cardiac output (L/min) by inert gas rebreathing and cerebral blood flow of the total gray matter (mL/100 g per min) using arterial spin labeling magnetic resonance imaging in resting state less than 24 hours before TAVI and at 3‐month follow‐up. Cerebral blood flow change was defined as the difference relative to baseline.

RESULTS

On average, cardiac output in patients with severe aortic valve stenosis increased from 4.0 ± 1.1 to 5.4 ± 2.4 L/min after TAVI (P = .003). The increase in cerebral blood flow after TAVI strongly varied between patients (7% ± 24%; P = .41) and related to the increase in cardiac output, with an 8.2% (standard error = 2.3%; P = .003) increase in cerebral blood flow per every additional liter of cardiac output following the TAVI procedure.

CONCLUSION

Following TAVI, there was an association of increase in cardiac output with increase in cerebral blood flow. These findings encourage future larger studies to determine the influence of TAVI on cerebral blood flow and cognitive function.

The central nervous system and heart failure

The view that chronic heart failure was exclusively a disease of the heart dominated the cardiovascular literature until relatively recently. However, over the last 40 years it has increasingly come to be seen as a multisystem disease. Aside from changes in the sympathetic and parasympathetic nervous systems and the renin-angiotensin-aldosterone system, adaptations to the lungs, muscles and gastrointestinal tract have been clearly documented. It is clear that the brain and CNS are also affected in patients with heart failure, although this is often under recognized. The purpose of this review is to summarize the changes in the structure and biochemical function of the CNS in patients with chronic heart failure and to discuss their potential importance.

Left ventricular ejection fraction is associated with small vessel disease in ischaemic stroke patients

BACKGROUND AND PURPOSE

The purpose was to evaluate the association between the left ventricular ejection fraction (LVEF) and cerebral small vessel disease (cSVD) in ischaemic stroke patients.

METHODS

Consecutive first-ever ischaemic stroke patients between 2010 and 2013 were included. White matter hyperintensity (WMH) volumes were rated using both the Fazekas score and quantitative methods on fluid-attenuated inversion recovery images. As spectra of cSVD, lacunes, cerebral microbleeds (CMBs) and enlarged perivascular spaces (EPVSs) were also evaluated. To assess the dose-response relationship between LVEF and cSVD, the burdens of each radiological marker and the total cSVD score were rated.

RESULTS

A total of 841 patients were included [median WMH volume 2.98 (1.22-10.50) ml; the frequencies of lacunes, CMBs and moderate to severe EPVSs were 38%, 31% and 35%, respectively]. In the multivariate analysis about predictors of WMH volumes, the LVEF (B = -0.052, P < 0.001) remained significant after adjusting for confounders. LVEF was also a predictor of lacunes [adjusted odds ratio (aOR) 0.978, P = 0.012], CMBs (aOR = 0.96, P < 0.001) and moderate to severe EPVSs (aOR = 0.94, P < 0.001) after adjusting for their confounders. The LVEF values were negatively correlated with the burdens of lacunes (P = 0.026), CMBs (P < 0.001) and EPVSs (P = 0.002). The total cSVD score also showed a negative association with LVEF in a dose-response manner (P < 0.001).

CONCLUSIONS

The burden of cSVD is negatively correlated with the LVEF in a dose-response manner. Our results suggest clues for further studies about determining the pathophysiology of cSVD.

Peak exercise stroke volume effects on cognitive impairment in community-dwelling people with preserved ejection fraction

AIMS

The association of vascular dysfunction and amyloid beta deposition attracted attentions for its relationship with cognitive decline. Previous studies show the correlation between the declined cardiac function and the cognitive impairment. In the present study, we analysed the association between cognitive functions and cardiac parameters in community-dwelling people with preserved ejection fraction without heart failure.

METHODS AND RESULTS

Subjects were 108 Japanese community-dwelling middle-aged and older adults with preserved ejection fraction (25 men and 83 women; mean age 74.7 years). Cardiac functional parameters at rest were assessed with B-type natriuretic peptide and echocardiography. The cardiopulmonary exercise test was used to test these parameters during exercise. Cognitive function was assessed with the Japanese version of the Montreal Cognitive Assessment (MoCA-J). Other indices were assessed biochemically, physiologically, and physically. There were significant correlations between MoCA-J score and age (r = -0.388), peak oxygen uptake (VO₂ , r = 0.201), peak VO₂ /heart rate (HR, r = 0.243), peak VO₂ /weight (r = 0.244), peak metabolic equivalents (r = 0.244), usual walking speed (r = -0.200), and the Timed Up and Go test (r = -0.230). Multiple linear regression analysis showed peak VO₂ /HR was an independent determinant of MoCA-J score after adjusting for potential confounders (B = 0.424). After 6 months of exercise training with 64 subjects, we found that the per cent change of peak VO₂ /HR was related to the per cent change of MoCA-J score (r = 0.296).

CONCLUSIONS

These results suggested that peak VO₂ /HR (an index of stroke volume at peak exercise) might be associated with cognitive impairment based on the vascular cascade hypothesis.

Aging modifies the effect of cardiac output on middle cerebral artery blood flow velocity

An association between cerebral blood flow (CBF) and cardiac output (CO) has been established in young healthy subjects. As of yet it is unclear how this association evolves over the life span. To that purpose, we continuously recorded mean arterial pressure (MAP; finger plethysmography), CO (pulse contour; CO‐trek), mean blood flow velocity in the middle cerebral artery (MCAV; transcranial Doppler ultrasonography), and end‐tidal CO₂ partial pressure (PetCO₂) in healthy young (19–27 years), middle‐aged (51–61 years), and elderly subjects (70–79 years). Decreases and increases in CO were accomplished using lower body negative pressure and dynamic handgrip exercise, respectively. Aging in itself did not alter dynamic cerebral autoregulation or cerebrovascular CO₂ reactivity. A linear relation between changes in CO and MCAV_mean was observed in middle‐aged (P < 0.01) and elderly (P = 0.04) subjects but not in young (P = 0.45) subjects, taking concurrent changes in MAP and PetCO₂ into account. These data imply that with aging, brain perfusion becomes increasingly dependent on CO.

Dynamic cerebral autoregulation is impaired during submaximal isometric handgrip in patients with heart failure

The incidence of neurological complications, including stroke and cognitive dysfunction, is elevated in patients with heart failure (HF) with reduced ejection fraction. We hypothesized that the cerebrovascular response to isometric handgrip (iHG) is altered in patients with HF. Adults with HF and healthy volunteers were included. Cerebral blood velocity (CBV; transcranial Doppler, middle cerebral artery) and arterial blood pressure (BP; Finometer) were continuously recorded supine for 6 min, corresponding to 1 min of baseline and 3 min of iHG exercise, at 30% maximum voluntary contraction, followed by 2 min of recovery. The resistance-area product was calculated from the instantaneous BP-CBV relationship. Dynamic cerebral autoregulation (dCA) was assessed with the time-varying autoregulation index estimated from the CBV step response derived by an autoregressive moving-average time-domain model. Forty patients with HF and 23 BP-matched healthy volunteers were studied. Median left ventricular ejection fraction was 38.5% (interquartile range: 0.075%) in the HF group. Compared with control subjects, patients with HF exhibited lower time-varying autoregulation index during iHG, indicating impaired dCA ( P < 0.025). During iHG, there were steep rises in CBV, BP, and heart rate in control subjects but with different temporal patterns in HF, which, together with the temporal evolution of resistance-area product, confirmed the disturbance in dCA in HF. Patients with HF were more likely to have impaired dCA during iHG compared with age-matched control subjects. Our results also suggest an impairment of myogenic, neurogenic, and metabolic control mechanisms in HF. The relationship between impaired dCA and neurological complications in patients with HF during exercise deserves further investigation. NEW & NOTEWORTHY Our findings provide the first direct evidence that cerebral blood flow regulatory mechanisms can be affected in patients with heart failure during isometric handgrip exercise. As a consequence, eventual blood pressure modulations are buffered less efficiently and metabolic demands may not be met during common daily activities. These deficits in cerebral autoregulation are compounded by limitations of the systemic response to isometric exercise, suggesting that patients with heart failure may be at greater risk for cerebral events during exercise.

Subclinical Compromise in Cardiac Strain Relates to Lower Cognitive Performances in Older Adults

BACKGROUND

Global longitudinal strain (GLS), reflecting total shortening of the myocardium during the cardiac cycle, has emerged as a more precise myocardial function measure than left ventricular ejection fraction (LVEF). Longitudinal strain may be selectively affected in subclinical heart disease, even in the presence of normal LVEF. This study examines subclinical cardiac dysfunction, assessed by GLS and LVEF, and cognition among older adults.

METHODS AND RESULTS

Vanderbilt Memory and Aging Project participants who were free of clinical dementia, stroke, and heart failure (n=318, 73±7 years, 58% male) completed neuropsychological assessment and cardiac magnetic resonance to quantify GLS and LVEF. Linear regression models related GLS and LVEF to neuropsychological performances, adjusting for age, sex, race/ethnicity, education, Framingham Stroke Risk Profile, cognitive diagnosis, and APOE*ε4 status. Models were repeated with a cardiac×cognitive diagnosis interaction term. Compromised GLS (reflected by higher values) related to worse naming (β=-0.07, P=0.04), visuospatial immediate recall (β=-0.83, P=0.03), visuospatial delayed recall (β=-0.22, P=0.03), and verbal delayed recall (β=-0.11, P=0.007). LVEF did not relate to worse performance on any measure (P>0.18). No diagnostic interactions were observed.

CONCLUSIONS

Our study results are among the first to suggest that compromised GLS relates to worse episodic memory and language performance among older adults who are free of clinical dementia, stroke, and heart failure. Subclinical cardiac dysfunction may correlate with cognitive health in late life, even when LVEF remains normal. The results add to growing evidence that GLS may be a more sensitive and preferred method for quantifying subclinical changes in cardiac function.

Relative contributions of systemic hemodynamic variables to cerebral autoregulation during orthostatic stress

Postural changes impair the ability of the cerebrovasculature to buffer against dynamic pressure fluctuations, but the mechanisms underlying this impairment have not been elucidated. We hypothesized that autoregulatory impairment may reflect the impact of static central volume shifts on hemodynamic factors other than arterial pressure (AP). In 14 young volunteers, we assessed the relation of fluctuations in cerebral blood flow (CBF) to those in AP, cardiac output, and CO₂, during oscillatory lower body pressure (LBP) (±20 mmHg at 0.01 and 0.06 Hz) at three static levels (-20, 0, and +20 mmHg). Static and dynamic changes in AP, cardiac output, and CO₂ explained over 70% of the variation in CBF fluctuations. However, their contributions were different across frequencies and levels: dynamic AP changes explained a substantial proportion of the variation in faster CBF fluctuations (partial R² = 0.75, standardized β = 0.83, P < 0.01), whereas those in CO₂ explained the largest portion of the variation in slow fluctuations (partial R² = 0.43, β = 0.51, P < 0.01). There was, however, a major contribution of slow dynamic AP changes during negative (β = 0.43) but not neutral (β = 0.05) or positive (β = -0.07) LBP. This highlights the differences in contributions of systemic variables to dynamic and static autoregulation and has important implications for understanding orthostatic intolerance. NEW & NOTEWORTHY While fluctuations in blood pressure drive faster fluctuations in cerebral blood flow, overall level of CO₂ and the magnitude of its fluctuations, along with cardiac output, determine the magnitude of slow ones. The effect of slow blood pressure fluctuations on cerebrovascular responses becomes apparent only during pronounced central volume shifts (such as when standing). This underlines distinct but interacting contributions of static and dynamic changes in systemic hemodynamic variables to the cerebrovascular regulation.

Lower cardiac index levels relate to lower cerebral blood flow in older adults

OBJECTIVE

To assess cross-sectionally whether lower cardiac index relates to lower resting cerebral blood flow (CBF) and cerebrovascular reactivity (CVR) among older adults.

METHODS

Vanderbilt Memory & Aging Project participants free of stroke, dementia, and heart failure were studied (n = 314, age 73 ± 7 years, 59% male, 39% with mild cognitive impairment). Cardiac index (liters per minute per meter squared) was quantified from echocardiography. Resting CBF (milliliters per 100 grams per minute) and hypercapnia-induced CVR were quantified from pseudo-continuous arterial spin-labeling MRI. Linear regressions with ordinary least-square estimates related cardiac index to regional CBF, with adjustment for age, education, race/ethnicity, Framingham Stroke Risk Profile score (systolic blood pressure, antihypertensive medication use, diabetes mellitus, current cigarette smoking, left ventricular hypertrophy, prevalent cardiovascular disease [CVD], atrial fibrillation), APOE ε4 status, cognitive diagnosis, and regional tissue volume.

RESULTS

Lower cardiac index corresponded to lower resting CBF in the left (β = 2.4, p = 0.001) and right (β = 2.5, p = 0.001) temporal lobes. Results were similar when participants with prevalent CVD and atrial fibrillation were excluded (left temporal lobe β = 2.3, p = 0.003; right temporal lobe β = 2.5, p = 0.003). Cardiac index was unrelated to CBF in other regions assessed (p > 0.25) and CVR in all regions (p > 0.05). In secondary cardiac index × cognitive diagnosis interaction models, cardiac index and CBF associations were present only in cognitively normal participants and affected a majority of regions assessed with effects strongest in the left (p < 0.0001) and right (p < 0.0001) temporal lobes.

CONCLUSIONS

Among older adults without stroke, dementia, or heart failure, systemic blood flow correlates with cerebral CBF in the temporal lobe, independently of prevalent CVD, but not CVR.

Long-term outcomes and management of the heart transplant recipient

Cardiac transplantation remains the gold standard in the treatment of advanced heart failure. With advances in immunosuppression, long-term outcomes continue to improve despite older and higher risk recipients. The median survival of the adult after heart transplantation is currently 10.7 years. While early graft failure and multiorgan system dysfunction are the most important causes of early mortality, malignancy, rejection, infection, and cardiac allograft vasculopathy contribute to late mortality. Chronic renal dysfunction is common after heart transplantation and occurs in up to 68% of patients by year 10, with 6.2% of patients requiring dialysis and 3.7% undergoing renal transplant. Functional outcomes after heart transplantation remain an area for improvement, with only 26% of patients working at 1-year post-transplantation, and are likely related to the high incidence of depression after cardiac transplantation. Areas of future research include understanding and managing primary graft dysfunction and reducing immunosuppression-related complications.

Clinical Characteristics of Transplant-associated Encephalopathy in Children

We aimed to analyze characteristics of encephalopathy after both hematopoietic stem cell and solid organ pediatric transplantation. We retrospectively reviewed medical records of 662 pediatric transplant recipients (201 with liver transplantation [LT], 55 with heart transplantation [HT], and 67 with kidney transplantation [KT], 339 with allogeneic hematopoietic stem cell transplantation [HSCT]) who received their graft organs at Asan Medical Center between January 2000 and July 2014. Of the 662 patients, 50 (7.6%) experienced encephalopathy after transplantation. The incidence of encephalopathy was significantly different according to the type of organ transplant: LT, 16/201 (8.0%), HT, 13/55 (23.6%), KT, 5/67 (7.5%), and HSCT, 16/339 (4.7%) (P < 0.001). Drug-induced encephalopathy (n = 14) was the most common encephalopathy for all transplant types, but particularly after HSCT. Hypertensive encephalopathy was the most common after KT and HT, whereas metabolic encephalopathy was the most common after LT. The median time to encephalopathy onset also differed according to the transplant type: 5 days after KT (range 0-491 days), 10 days after HT (1-296 days), 49.5 days after HSCT (9-1,405 days), and 39 days after LT (1-1,092 days) (P = 0.018). The mortality rate among patients with encephalopathy was 42.0% (n = 21/50). Only 5 patients died of neurologic complications. Transplant-associated encephalopathy presented different characteristics according to the type of transplant. Specialized diagnostic approach for neurologic complications specific to the type of transplant may improve survival and quality of life in children after transplantation.

The N-terminal pro B-type natriuretic peptide, and risk of dementia and cognitive decline: a 10-year follow-up study in the general population

BACKGROUND

The N-terminal pro B-type natriuretic peptide (NT-proBNP) has a well-documented prognostic value for cardiovascular disease (CVD) and higher levels are associated with cognitive-dysfunction in patients with CVD. However, how NT-proBNP relates to incident dementia and cognitive-decline in community-dwelling persons is unknown.

METHODS

Between 1997 and 2001, serum NT-proBNP was measured in 6040 participants (mean age 69 years, 57% women) free of heart-failure and dementia from the Rotterdam Study. Participants were continuously followed-up for incident dementia until 2012, for 56,616 person-years. Cognition was assessed at baseline and reassessed between 2002 and 2006 by Letter-Digit-Substitution-task, Stroop test and Word-Fluency test. Associations of NT-proBNP with dementia (555 cases), Alzheimer's disease (357 cases) and vascular dementia (32 cases) were assessed linearly, and in quartiles using Cox regression. Associations of NT-proBNP with cognitive-decline were assessed using multiple linear regression. All analyses were repeated after excluding patients with CVD.

RESULTS

Higher NT-proBNP was associated with a higher risk of dementia, even after excluding patients with CVD and adjusting for cardiovascular risk factors, HR per SD 1.27 (95% CI 1.13 to 1.44). Associations were particularly strong for vascular dementia, HR per SD 2.04 (95% CI 1.18 to 3.55), but also for Alzheimer's disease when comparing the second and third quartile with first. Higher NT-proBNP was cross-sectionally associated with poorer performance in multiple cognitive tests but longitudinally only in Letter-Digit-Substitution-task.

CONCLUSIONS

NT-proBNP reflecting subclinical CVD is associated with dementia, particularly vascular dementia. NT-proBNP can be a useful marker of imminent cognitive-decline and dementia in absence of clinical CVD.

Cardiac Output and Cerebral Blood Flow

Cerebral blood flow (CBF) is rigorously regulated by various powerful mechanisms to safeguard the match between cerebral metabolic demand and supply. The question of how a change in cardiac output (CO) affects CBF is fundamental, because CBF is dependent on constantly receiving a significant proportion of CO. The authors reviewed the studies that investigated the association between CO and CBF in healthy volunteers and patients with chronic heart failure. The overall evidence shows that an alteration in CO, either acutely or chronically, leads to a change in CBF that is independent of other CBF-regulating parameters including blood pressure and carbon dioxide. However, studies on the association between CO and CBF in patients with varying neurologic, medical, and surgical conditions were confounded by methodologic limitations. Given that CBF regulation is multifactorial but the various processes must exert their effects on the cerebral circulation simultaneously, the authors propose a conceptual framework that integrates the various CBF-regulating processes at the level of cerebral arteries/arterioles while still maintaining autoregulation. The clinical implications pertinent to the effect of CO on CBF are discussed. Outcome research relating to the management of CO and CBF in high-risk patients or during high-risk surgeries is needed.

Possible neurocognitive benefits of exercise in persons with heart failure

More than 6 million Americans have heart failure (HF) and more than 500,000 are diagnosed each year. In addition to its many adverse medical consequences, HF is also a significant risk factor for neurological disorders like Alzheimer's disease and associated with cognitive impairment long prior to the onset of these conditions. Converging bodies of literature suggest cognitive dysfunction in HF may be at least partially modifiable. One key mechanism for cognitive improvement is improved cerebral blood flow, which may be possible with exercise in patients with HF. This brief review provides a model for the likely neurocognitive benefits of exercise in HF and encourages further work in this area.

Obesity as a risk factor for poor neurocognitive outcomes in older adults with heart failure

Heart failure (HF) has reached epidemic proportions and is a significant contributor to poor outcomes. HF is an established risk factor for Alzheimer's disease, vascular dementia, and abnormalities on neuroimaging. Moreover, up to 80% of HF patients also exhibit milder impairments on cognitive tests assessing attention, executive function, memory, and language. The mechanisms of cognitive impairment in HF are not entirely clear and involve a combination of physiological processes that negatively impact the brain. Cerebral hypoperfusion and common comorbid conditions in HF are among the most commonly proposed contributors to poor neurocognitive outcomes in this population. Obesity is another likely risk factor for adverse brain changes and cognitive impairment in HF, as it is a known contributor to neurocognitive outcomes in healthy and patient samples. This paper reviews the literature on HF and cognitive function and introduces obesity as a significant risk factor for poor neurocognitive outcomes in this population.

Heart failure and Alzheimer's disease

It has recently been proposed that heart failure is a risk factor for Alzheimer's disease. Decreased cerebral blood flow and neurohormonal activation due to heart failure may contribute to the dysfunction of the neurovascular unit and cause an energy crisis in neurons. This leads to the impaired clearance of amyloid beta and hyperphosphorylation of tau protein, resulting in the formation of amyloid beta plaques and neurofibrillary tangles. In this article, we will summarize the current understanding of the relationship between heart failure and Alzheimer's disease based on epidemiological studies, brain imaging research, pathological findings and the use of animal models. The importance of atherosclerosis, myocardial infarction, atrial fibrillation, blood pressure and valve disease as well as the effect of relevant medications will be discussed.

Low cardiac index is associated with incident dementia and Alzheimer disease: the Framingham Heart Study

BACKGROUND

Cross-sectional epidemiological and clinical research suggests that lower cardiac index is associated with abnormal brain aging, including smaller brain volumes, increased white matter hyperintensities, and worse cognitive performances. Lower systemic blood flow may have implications for dementia among older adults.

METHODS AND RESULTS

A total of 1039 Framingham Offspring Cohort participants free of clinical stroke, transient ischemic attack, and dementia formed our sample (age, 69±6 years; 53% women). Multivariable-adjusted proportional hazard models adjusting for Framingham Stroke Risk Profile score (age, sex, systolic blood pressure, antihypertensive medication, diabetes mellitus, cigarette smoking, cardiovascular disease history, atrial fibrillation), education, and apolipoprotein E4 status related cardiac magnetic resonance imaging-assessed cardiac index (cardiac output divided by body surface area) to incident all-cause dementia and Alzheimer disease (AD). Over the median 7.7-year follow-up period, 32 participants developed dementia, including 26 cases of AD. Each 1-SD unit decrease in cardiac index increased the relative risk of both dementia (hazard ratio [HR]=1.66; 95% confidence interval [CI], 1.11-2.47; P=0.013) and AD (HR=1.65; 95% CI, 1.07-2.54; P=0.022). Compared with individuals with normal cardiac index, individuals with clinically low cardiac index had a higher relative risk of dementia (HR=2.07; 95% CI, 1.02-4.19; P=0.044). If participants with clinically prevalent cardiovascular disease and atrial fibrillation were excluded (n=184), individuals with clinically low cardiac index had a higher relative risk of both dementia (HR=2.92; 95% CI, 1.34-6.36; P=0.007) and AD (HR=2.87; 95% CI, 1.21-6.80; P=0.016) compared with individuals with normal cardiac index.

CONCLUSION

Lower cardiac index is associated with an increased risk for the development of dementia and AD.

Relationship between cognitive impairment and echocardiographic parameters: a review

With >24 million people affected worldwide, dementia is one of the main public health challenges modern medicine has to face. The path leading to dementia is often long, with a wide spectrum of clinical presentations, and preceded by a long preclinical phase. Previous studies have demonstrated that clinical strokes and covert vascular lesions of the brain contribute to the risk for developing dementia. Although it is not yet known whether preventing such lesions reduces the risk for dementia, it is likely that starting preventive measures early in the course of the disease may be beneficial. Echocardiography is a widely available, relatively inexpensive, noninvasive imaging modality whereby morphologically or hemodynamically derived parameters may be integrated easily into a risk assessment model for dementia. The aim of this review is to analyze the information that has accumulated over the past two decades on the prognostic value of echocardiographic factors in cognitive impairment. The associations between cognitive impairment and echocardiographic parameters, including left ventricular systolic and diastolic indices, left atrial morphologic parameters, cardiac output, left ventricular mass, and aortic root diameter, have previously been reported. In the light of these studies, it appears that echocardiography may help further improve currently used risk assessment models by allowing detection of subclinical cardiac abnormalities associated with future cognitive impairment. However, many limitations, including methodologic heterogeneity and the observational designs of these studies, restrict the scope of these results. Further prospective studies are required before integrating echocardiography into a preventive strategy.

Subfoveal choroidal thickness in patients with chronic heart failure analyzed by spectral-domain optical coherence tomography

PURPOSE

To evaluate the subfoveal choroidal thickness (SFCT) measured by enhanced depth imaging optical coherence tomography (EDI-OCT) in eyes of chronic heart failure (CHF) patients.

METHODS

Fifty-six patients with CHF and 56 age- and gender-matched healthy individuals were enrolled. The SFCT was measured by EDI-OCT. The ejection fraction of left ventricle (EFLV), age, intraocular pressure (IOP), axial length (AL), systolic and diastolic blood pressure, and ocular perfusion pressure (OPP) were also measured.

RESULTS

Mean SFCT was 181.2 ± 80.23 μm in the study group and 283.6 ± 52.4 μm in the control group (p = 0.000). There was a statistically significant correlation between the SFCT and each of EFLV and age. SFCT value was not statistically significantly associated with AL, IOP and OPP.

CONCLUSION

Our results suggest that SFCT is lower in eyes of CHF patients compared to age- and gender-matched healthy individuals.

Prevalence of memory disorders in ambulatory patients aged ≥70 years with chronic heart failure (from the EFICARE study)

The aim of this multicenter observational study conducted in France was to determine the prevalence of memory impairment in ambulatory patients aged≥70 years with chronic heart failure (HF). Two hundred ninety-one cardiologists recruited 912 ambulatory patients with HF (mean age 79.2±5.8 years) from January to November 2009. Memory was evaluated by the delayed-recall Memory Impairment Screen (MIS-D). Memory impairment was defined as MIS-D score≤6 and severe memory impairment as MIS-D score≤4. HF was diagnosed 4.4±4.8 years earlier and mean left ventricular ejection fraction was 43.6±12.0%. Memory impairment was found in 416 subjects (45.6%, 95% confidence interval 42.4 to 48.8) and severe memory impairment in 213 subjects (23.4%, 95% confidence interval 20.6 to 26.1), whereas cardiologists only suspected memory impairment in 109 patients (12%; before evaluation by MIS). Determinants of memory disorders included older age, lower education level, depression, history of stroke, renal failure, and less regular physical activity. The severity of memory impairment increased with increasing severity of HF (New York Heart Association classification; p<0.00001). In conclusion, memory impairment in older patients with HF is common. The use of a simple-to-use tool such as the MIS-D may identify patients at risk and enable implementation of management strategies to improve therapeutic compliance.

Decreased physical activity predicts cognitive dysfunction and reduced cerebral blood flow in heart failure

OBJECTIVE

Cognitive impairment in heart failure (HF) is believed to result from brain hypoperfusion subsequent to cardiac dysfunction. Physical inactivity is prevalent in HF and correlated with reduced cardiac and cognitive function. Yet, no longitudinal studies have examined the neurocognitive effects of physical inactivity in HF. The current study examined whether reduced physical activity increases risk for cognitive impairment and brain hypoperfusion over time in HF.

METHODS

At baseline and 12 months later, 65 HF patients underwent neuropsychological testing, transcranial Doppler ultrasonography, and were asked to wear an accelerometer for seven days.

RESULTS

Lower baseline step count and less time spent in moderate free-living activity best predicted worse attention/executive function and decreased cerebral perfusion at the 12-month follow-up. Decreased baseline cerebral perfusion also emerged as a strong predictor of poorer 12-month attention/executive function.

CONCLUSIONS

Lower physical activity predicted worse cognition and cerebral perfusion 12 months later in HF. Physical inactivity in HF may contribute to cognitive impairment and exacerbate risk for conditions such as Alzheimer's disease. Larger studies are needed to elucidate the mechanisms by which physical inactivity leads to cognitive dysfunction in HF, including clarification of the role of cerebral hypoperfusion.

Neurologic aspects of heart transplantation

Cardiac transplantation remains the best treatment option for patients with end-stage, NYHA class IV heart failure who have failed conventional therapy. However, transplant rates have remained static largely due to limited organ donor supplies. Therefore, appropriate allocation of this precious resource is critical to maximize benefit, both at a patient level and at a societal level. Neurologic diseases, such as cerebrovascular disease and peripheral neuropathy, are prevalent in this patient population, as the major risk factors for heart disease place patients at risk for neurologic disease as well. Examples include hypertension, smoking, hypercholesterolemia, obesity, and diabetes. Pretransplant neurologic evaluation is very important to identify conditions that may limit survival after cardiac transplantation. In general, systemic diseases exacerbated by immunosuppression, conditions limiting ability to rehabilitate, and dementias are considered contraindications. Post-transplant neurologic complications are divided into central versus peripheral, and early versus late. The most common early complication is ischemic stroke. Other serious complications include hemorrhagic stroke, encephalopathy, and critical illness neuropathy. Over the long term, post-transplant immunosuppressive regimens are considered "a double edged sword." Although immunosuppressive medications are critical to preventing rejection and allograft dysfunction, they do have significant risk of morbidity and mortality associated with them, including neurologic side-effects. These include: (1) drug toxicities, such as lowering of seizure thresholds; (2) encephalopathy, such as posterior reversible encephalopathy syndrome (PRES); (3) infections; (4) malignancies, such as post-transplant lymphoproliferative disorder (PTLD). Many of the same considerations discussed in adult heart transplant recipients apply to pediatric heart transplant recipients as well. In children, seizures are the most common neurologic complication, although other neurologic complication rates are comparable.

Cerebral blood flow as a marker for recovery of left ventricular systolic dysfunction in patients with idiopathic dilated cardiomyopathy

BACKGROUND

This study was intended to investigate whether cerebral blood flow (CBF) could predict the recovery of left ventricular (LV) systolic dysfunction in patients with idiopathic dilated cardiomyopathy (DCMP).

METHODS AND RESULTS

Between July 2001 and March 2009, 107 patients who had been diagnosed with idiopathic DCMP underwent radionuclide angiography to assess their CBF. The recovery of LV systolic dysfunction was defined as recovery of the ejection fraction (EF) measured by transthoracic echocardiography to a level of 40% or greater and an increase of 10% or greater in its absolute value during follow-up. The EF was followed for at least 36 months if it did not recover. Thirty-four patients (31.8%) recovered and had greater CBF than the nonrecovered patients (41.9 ± 3.4 vs. 37.1 ± 4.9 mL/min/100g, P < .001). On multivariate logistic analysis, CBF (odds ratio 1.216) and symptom duration (odds ratio 0.952) were independent predictors of the recovery of LV systolic dysfunction. There was also a weak negative correlation between CBF and symptom duration (r = -0.334, P < .001). Furthermore, CBF was associated with LVEF improvement seen at the 1- and 2-year follow-up times according to multiple linear regression analysis.

CONCLUSIONS

CBF was associated with recovery of LV systolic dysfunction in patients with idiopathic DCMP. Therefore, measurement of CBF would be helpful to predict the clinical course of their disease.

The relationship of depression and disease stage to patient perceptions of Parkinson’s disease

The present study aimed to perform an in-depth exploration of perceptions of Parkinson’s disease (PD) and their relationship to depression and disease stage using semi-structured interviews. 37 participants with PD formed four groups: depressed and non-depressed with either mild or moderate-severe stage PD. Interviews were analysed using Framework Analysis. Moderate-severe stage patients reported a greater variety of perceptions than those with mild symptoms. Depressed and non-depressed patients differed in their perceptions of the consequences, treatment control and emotional reaction to PD. Helping patients to adjust life goals to accommodate PD and employ adaptive coping strategies may help to relieve depressive symptoms in PD.

Relation of left ventricular ejection fraction to cognitive aging (from the Framingham Heart Study)

Heart failure is a risk factor for Alzheimer's disease and cerebrovascular disease. In the absence of heart failure, it was hypothesized that left ventricular ejection fraction (LVEF), an indicator of cardiac dysfunction, would be associated with preclinical brain magnetic resonance imaging (MRI) and neuropsychological markers of ischemia and Alzheimer disease in the community. Brain MRI, cardiac MRI, neuropsychological, and laboratory data were collected from 1,114 Framingham Heart Study Offspring Cohort participants free from clinical stroke or dementia (aged 40 to 89 years, mean age 67 ± 9 years, 54% women). Neuropsychological and neuroimaging markers of brain aging were related to cardiac MRI-assessed LVEF. In multivariable-adjusted linear regressions, LVEF was not associated with any brain aging variable (p values >0.15). However, LVEF quintile analyses yielded several U-shaped associations. Compared to the referent (quintile 2 to 4), the lowest quintile (quintile 1) LVEF was associated with lower mean cognitive performance, including Visual Reproduction Delayed Recall (β = -0.27, p <0.001) and Hooper Visual Organization Test (β = -0.27, p <0.001). Compared to the referent, the highest quintile (quintile 5) LVEF values also were associated with lower mean cognitive performance, including Logical Memory Delayed Recall (β = -0.18, p = 0.03), Visual Reproduction Delayed Recall (β = -0.17, p = 0.03), Trail Making Test Part B - Part A (β = -0.22, p = 0.02), and Hooper Visual Organization Test (β = -0.20, p = 0.02). Findings were similar when analyses were repeated excluding prevalent cardiovascular disease. In conclusion, although these observational cross-sectional data cannot establish causality, they suggest a nonlinear association between LVEF and measures of accelerated cognitive aging.

Treatment of vascular dementia. Recommendations of the Scientific Department of Cognitive Neurology and Aging of the Brazilian Academy of Neurology

Scientific Department of Cognitive Neurology and Aging of ABN had a consensus meeting to write recommendations on treatment of vascular dementia, there was no previous issue. This disease has numerous particularities and can be considered a preventable dementia. Prevention treatment is primary care of vascular risk factors or a secondary prevention of factors that could cause recurrence of ischemic or hemorrhagic brain modifications. In these guidelines we suggested only symptomatic treatment, pharmacologic or non-pharmacologic. We have reviewed current publications on MEDLINE (PubMed), LILACS e Cochrane Library databases. Recommendations are concern to the following factors and their prevention evidences, association, or treatment of vascular dementia: physical activity, tobacco use, diet and food supplements, arterial hypertension, diabetes mellitus, obesity, statins, cardiac failure, atrial fibrillation, antithrombotics, sleep apnea, carotid revascularization, symptomatic pharmacological treatment.

Pumps, aqueducts, and drought management: vascular physiology in vascular cognitive impairment

Vascular cognitive impairment has been traditionally defined by structural pathology, an accumulation of infarcts, leading to progressive cognitive decline. Recent evidence, however, suggests that cognitive impairment may be independently mediated by hemodynamic dysfunction, including global and hemispheral hypoperfusion and altered cerebral blood flow regulation. In this review, we examine evidence for the contribution of hemodynamic impairment to cognitive dysfunction in the setting of large vessel disease, cardiac failure, and microvascular disease. If there is a hemodynamic component of vascular cognitive impairment, then treatments proposed to correct impaired vascular physiology may reasonably be expected to treat the cognitive dysfunction as well.

Association between hypotension, low ejection fraction and cognitive performance in cardiac patients

BACKGROUND AND PURPOSE

Impaired cardiac function can adversely affect the brain via decreased perfusion. The purpose of this study was to determine if cardiac ejection fraction (EF) is associated with cognitive performance, and whether this is modified by low blood pressure.

METHODS

Neuropsychological testing evaluating multiple cognitive domains, measurement of mean arterial pressure (MAP), and measurement of EF were performed in 234 individuals with coronary artery disease. The association between level of EF and performance within each cognitive domain was explored, as was the interaction between low MAP and EF.

RESULTS

Adjusted global cognitive performance, as well as performance in visuoconstruction and motor speed, was significantly directly associated with cardiac EF. This relationship was not entirely linear, with a steeper association between EF and cognition at lower levels of EF than at higher levels. Patients with low EF and low MAP at the time of testing had worse cognitive performance than either of these alone, particularly for the global and motor speed cognitive scores.

CONCLUSIONS

Low EF may be associated with worse cognitive performance, particularly among individuals with low MAP and for cognitive domains typically associated with vascular cognitive impairment. Further care should be paid to hypotension in the setting of heart failure, as this may exacerbate cerebral hypoperfusion.

Cardiac output as a potential risk factor for abnormal brain aging

Heart failure has served as a clinically useful model for understanding how cardiac dysfunction is associated with neuroanatomic and neuropsychological changes in aging adults, theoretically because systemic hypoperfusion disrupts cerebral perfusion, contributing to clinical brain injury. This review summarizes more recent data suggesting that subtle cardiac dysfunction or low normal levels of cardiac function, as quantified by cardiac output, are related to cognitive and neuroimaging markers of abnormal brain aging in the absence of heart failure or severe cardiomyopathy. Additional work is required, but such associations suggest that reduced cardiac output may be a risk factor for Alzheimer's disease (AD) and abnormal brain aging through the propagation or exacerbation of neurovascular processes, microembolism due to thrombosis, and AD neuropathological processes. Such mechanistic pathways are discussed in the context of a theoretical model that posits a direct pathway of injury between cardiac output and abnormal brain aging (i.e., reduced systemic blood flow disrupts cerebral blood flow homeostasis), contributing to clinical brain injury, independent of shared risk factors for both cardiac dysfunction and abnormal brain aging.

Cardiac index is associated with brain aging: the Framingham Heart Study

BACKGROUND

Cardiac dysfunction is associated with neuroanatomic and neuropsychological changes in aging adults with prevalent cardiovascular disease, theoretically because systemic hypoperfusion disrupts cerebral perfusion, contributing to subclinical brain injury. We hypothesized that cardiac function, as measured by cardiac index, would be associated with preclinical brain magnetic resonance imaging (MRI) and neuropsychological markers of ischemia and Alzheimer disease in the community.

METHODS AND RESULTS

Brain MRI, cardiac MRI, neuropsychological, and laboratory data were collected on 1504 Framingham Offspring Cohort participants free of clinical stroke, transient ischemic attack, or dementia (age, 61+/-9 years; 54% women). Neuropsychological and brain MRI variables were related to cardiac MRI-assessed cardiac index (cardiac output/body surface area). In multivariable-adjusted models, cardiac index was positively related to total brain volume (P=0.03) and information processing speed (P=0.02) and inversely related to lateral ventricular volume (P=0.048). When participants with clinically prevalent cardiovascular disease were excluded, the relation between cardiac index and total brain volume remained (P=0.02). Post hoc comparisons revealed that participants in the bottom cardiac index tertile (values <2.54) and middle cardiac index tertile (values between 2.54 and 2.92) had significantly lower brain volumes (P=0.04) than participants in the top cardiac index tertile (values >2.92).

CONCLUSIONS

Although observational data cannot establish causality, our findings are consistent with the hypothesis that decreasing cardiac function, even at normal cardiac index levels, is associated with accelerated brain aging.

Cerebrovascular complications after heart transplantation

Neurological complications in orthotopic heart transplantation represent a major cause of morbidity and mortality despite successful transplantation. The most frequent perioperative neurological complications are delirium or encephalopathy. In this period cerebrovascular complication ranges between 5-11%. After the perioperative period, the 5-year stroke risk after cardiac transplantation is 4.1%. In a retrospective study conducted with 314 patients who underwent cardiac transplantation, it was found that 20% of cerebrovascular complications occurred within the first two weeks after transplantation, while 80% occurred in the late postoperative phase. Of these, ischemic stroke is the most common subtype. In the perioperative periode, hemodynamic instability, cardiac arrest, extracorporeal circulation over 2 hours, prior history of stroke, and carotid stenosis greater than 50% have been reported to be risk factors for the occurrence of cerebrovascular complications. Perioperative cerebrovascular complications are associated with higher mortality and poor functional outcome at one year follow-up.After the perioperative period, the only factor that has been significantly associated with an increased risk of cerebrovascular complications is a history of prior stroke, either ischemic or hemorrhagic. Other associated factors include unknown atrial fibrillation, septic emboli from endocarditis, cardiac catheterization and perioperative hemodynamic shock. According to the TOAST etiologic classification, the most prevalent etiologic subtype of ischemic stroke is undetermined cause.

Effect of cardiac resynchronization therapy on cerebral blood flow

Decreased cerebral blood flow is frequently observed in patients with heart failure, and this could be the result of impaired cardiac systolic function. Cardiac resynchronization therapy (CRT) improves cardiac function and heart failure symptoms in selected patients. The effects of CRT on cerebral blood flow have not been previously evaluated. In the present study, left ventricular systolic function and cerebral blood flow were assessed in 35 patients with heart failure, before and 6 months after CRT. Additionally, 15 patients with heart failure, who were not candidates for CRT, were included as a control group. The peak systolic velocity, end-diastolic velocity, mean velocity, and pulsatility index ([peak systolic velocity--end-diastolic velocity]/mean velocity) were obtained using transcranial Doppler from the right middle cerebral artery from the temporal window in all subjects. Response to CRT was defined as a reduction in the left ventricular end-systolic volume of > or =15%. At 6 months of follow-up, the peak systolic velocity had significantly increased from 83 +/- 20 cm/s to 100 +/- 20 cm/s (p = 0.001), the end-diastolic velocity had increased from 29 +/- 7 cm/s to 37 +/- 8 cm/s (p <0.001), and the mean velocity had increased from 47 +/- 10 cm/s to 58 +/- 11 cm/s (p <0.001) only in the responders to CRT. In contrast, no significant changes in cerebral blood flow were observed in the nonresponders and the controls. In conclusion, CRT induced an increase in cerebral blood flow in patients with heart failure. This increase in cerebral blood flow was related to the improvement in left ventricular systolic function.