Improvement of cerebral blood flow and cognitive function following pacemaker implantation in patients with bradycardia

Pacemaker Implants and Their Influence on the Daily Life of Patients with Dementia with Lewy Bodies: A Qualitative Case Study

INTRODUCTION

Dementia with Lewy bodies (DLB) is an incurable form of dementia associated with detriments to the daily life of patients and carers from their family. Symptoms of orthostatic hypotension, syncope, and falls are supportive of DLB diagnosis. These symptoms may also be present among people with sick sinus syndrome (SSS), and subsequent pacemaker treatment to manage bradyarrhythmia is associated with improved cognitive function. The prevalence of SSS seems to be higher among people with underlying Lewy body pathology compared to the general age-matched population (5.2% vs. 0.17%). To our knowledge, how people with DLB and their family carers may experience pacemaker treatment to manage bradyarrhythmia has not been previously reported. Therefore, the aim of this study was to explore how people with DLB experience daily life following a pacemaker implant to manage associated symptoms of bradyarrhythmia.

METHODS

A qualitative case study design was used. Two men with DLB and their spouse carers were repeatedly interviewed as a dyad within 1 year following implant of a dual-chamber rate-adaptive (DDD-CLS) pacemaker to manage SSS in the men. Content analysis was used to assess the qualitative interview data collected.

RESULTS

Three categories emerged: (1) gaining control, (2) maintaining a social life, and (3) being influenced by concurrent diseases. Less syncope/falls and remote pacemaker monitoring increased a sense of control in everyday life, while perceived physical and/or cognitive improvements influenced social participation. The men were still affected by concurrent diseases, which continuously influenced each couple's daily life.

CONCLUSION

Identifying and managing concurrent bradyarrhythmia through a pacemaker implant could improve well-being for people with DLB.

Periprocedural complications of cardiac implantable electronic device implantation in very elderly patients with cognitive impairment: A prospective study

Very elderly people (over 80 years) with cardiac implantable electronic devices (CIEDs) indications often have a higher prevalence of aging comorbidity, among which cognitive impairment is not uncommon. This study aimed to investigate periprocedural complications of CIED implantation among very elderly patients with and without cognitive impairment. One hundred eighty patients ≥80 years of age indicated for CIED implantation were included in our study. During hospitalization, the cognitive evaluation was performed according to the Diagnostic and Statistical Manual of Mental Disorders (fifth edition). According to the cognitive test results, patients were divided into 2 groups (90 patients with normal cognitive function and 90 patients with cognitive impairment). Meanwhile, their physical parameters and laboratory measurements were completed. The procedural data and periprocedural complications were collected from both groups. The association between cognitive impairment and periprocedural complications was analyzed using univariate and multiple logistic regression analyses. During a one-month follow-up, the most frequent periprocedural complications in very elderly patients were pocket hematoma and thrombosis events. Cognitively impaired patients had a higher incidence of complications than normal cognitive patients. Multivariate regression analysis showed that cognitive impairment was positively correlated with periprocedural complications in very elderly patients. Cognitive impairment is associated with increased periprocedural complications of CIED implantation in very elderly patients.

Improvement of Cognitive Function and Interleukin 1 Beta Serum Concentrations Following Cardiac Pacemaker Implantation in Patients with Symptomatic Bradycardia

Background and aim: Bradyarrhythmias cause a low cerebral blood flow with secondary neuronal ischemia and cognitive dysfunction. This study aims to assess the effect of cardiac pacemaker implantation (PI) on the cognitive function and inflammatory markers (TNF alpha, IL1β). Material and method: We conducted a prospective observational study on a number of 31 patients with symptomatic bradyarrhythmias. We performed the cognitive function assessment by two tests (Mini-Mental State Examination and Trail Making Test A), cardiac output assessment (echocardiographic), and determination of IL 1β and TNF alpha serum concentrations before pacemaker implantation and after an average period of 42 days from pacemaker implantation.Results: After pacemaker implantation we observed an increase in the cardiac index by 0.71 L/min/m² (p < 0.001) and a better scoring in cognitive performance; the mean MMSE score increased by two points (p < 0.001), and Trail Making Test A had an improvement of 16 s (p < 0.001). Regarding the inflammatory markers, a significant decrease in IL-1β with 8.6 pg/mL (p = 0.049) after pacemaker implantation was observed. Additionally, we found statistically significant correlations between IL1β and TNF alpha (positive correlation, p = 0.005), between the MMSE and cardiac index (p < 0.001), between the Trail Making Test and cardiac index (p = 0.001), and between the MMSE and Trail Making Test (p = 0.003). Conclusions: Our findings suggest that cardiac pacemaker implantation was associated with improved cognitive function—possibly related to an increased cardiac output and with adecreased serum IL1β concentration in subjects with symptomatic bradycardia.

Neurologic complications of brady-arrhythmias

Brady-arrhythmias are responsible for both overt as well as subtle neurologic signs and symptoms, from the seemingly benign and nonspecific symptoms associated with presyncope, to sudden focal neurologic deficits. A brief background on nodal and infra-nodal brady-arrhythmias is provided, followed by extensive discussion regarding neurologic complications of brady-arrhythmias. The multiple mechanisms of and associations between Brady-arrhythmias and transient ischemic attacks and ischemic stroke are discussed. Controversial associations between brady-arrhythmias and neurologic disease are discussed as well, such as potential roles of brady-arrhythmias in cognitive impairment and sequelae of chronotropic incompetence; and the contribution of brady-arrhythmias to syncope and associated injuries to the nervous system. The chapter is written to stand on its own, with guidance toward other pertinent sections of this text where appropriate for further reading.

Neurological Injury and Cerebral Blood Flow in Single Ventricles Throughout Staged Surgical Reconstruction

BACKGROUND

Patients with a single ventricle experience a high rate of brain injury and adverse neurodevelopmental outcome; however, the incidence of brain abnormalities throughout surgical reconstruction and their relationship with cerebral blood flow, oxygen delivery, and carbon dioxide reactivity remain unknown.

METHODS

Patients with a single ventricle were studied with magnetic resonance imaging scans immediately prior to bidirectional Glenn (pre-BDG), before Fontan (BDG), and then 3 to 9 months after Fontan reconstruction.

RESULTS

One hundred sixty-eight consecutive subjects recruited into the project underwent 235 scans: 63 pre-BDG (mean age, 4.8±1.7 months), 118 BDG (2.9±1.4 years), and 54 after Fontan (2.4±1.0 years). Nonacute ischemic white matter changes on T2-weighted imaging, focal tissue loss, and ventriculomegaly were all more commonly detected in BDG and Fontan compared with pre-BDG patients (P<0.05). BDG patients had significantly higher cerebral blood flow than did Fontan patients. The odds of discovering brain injury with adjustment for surgical stage as well as ≥2 coexisting lesions within a patient decreased (63%-75% and 44%, respectively) with increasing amount of cerebral blood flow (P<0.05). In general, there was no association of oxygen delivery (except for ventriculomegaly in the BDG group) or carbon dioxide reactivity with neurological injury.

CONCLUSIONS

Significant brain abnormalities are commonly present in patients with a single ventricle, and detection of these lesions increases as children progress through staged surgical reconstruction, with multiple coexisting lesions more common earlier than later. In addition, this study demonstrated that BDG patients had greater cerebral blood flow than did Fontan patients and that an inverse association exists of various indexes of cerebral blood flow with these brain lesions. However, CO₂ reactivity and oxygen delivery (with 1 exception) were not associated with brain lesion development.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT02135081.

Case report: severe bradycardia, a reversible cause of "Cardio-Renal-Cerebral Syndrome"

Background

Cardio-Renal Syndromes were first classified in 2008 and divided into five subtypes. The type 1 Cardio-Renal Syndrome (CRS) is characterized by acute decompensation of heart failure leading to acute kidney injury (AKI). Bradyarrhythmia was not mentioned in the classification as a cause for low cardiac output (CO) in type 1 CRS. Besides, CRS was not previously associated with central nervous system (CNS) injury despite the fact that cardiac, renal and neurological diseases can coexist.

Case presentation

We report the case of a 93-year old diabetic man who presented for obnubilation. He had a slow atrial fibrillation, was not hypotensive and was not taking any beta-blocker. He developed, simultaneously, during his hospitalization, severe bradycardia (<35 beats per minute), oligoanuria and further neurological deterioration without profound hypotension. An ECG revealed a complete atrioventricular (AV) block and all his symptoms were completely reversed after pacemaker insertion. His creatinine decreased progressively afterwards and at discharge, he was conscious, alert and well oriented.

Conclusion

Our case highlights the importance of an early recognition of low cardiac output secondary to severe bradyarrhythmia and its concurrent repercussion on the kidney and the brain. This association of the CRS with CNS injury-that we called “Cardio-Renal-Cerebral Syndrome”–was successfully treated with permanent pacemaker implantation.

Mechanical Ventilation After Bidirectional Superior Cavopulmonary Anastomosis for Single-Ventricle Physiology: A Comparison of Pressure Support Ventilation and Neurally Adjusted Ventilatory Assist

We evaluated the effects of different respiratory assist modes on cerebral blood flow (CBF) and arterial oxygenation in single-ventricle patients after bidirectional superior cavopulmonary anastomosis (BCPA). We hypothesized that preserved auto-regulation of respiration during neurally adjusted ventilatory assist (NAVA) may have potential advantages for CBF and pulmonary blood flow regulation after the BCPA procedure. We enrolled 23 patients scheduled for BCPA, who underwent pressure-controlled ventilation (PCV), pressure support ventilation (PSV), and NAVA at two assist levels for all modes in a randomized order. PCV targeting large V T (15 mL × kg(-1)) resulted in lower CBF and oxygenation compared to targeting low V T (10 mL × kg(-1)). During PSV and NAVA, ventilation assist levels were titrated to reduce EAdi from baseline by 75 % (high assist) and 50 % (low assist). High assist levels during PSV (PSVhigh) were associated with lower PaCO2, PaO2, and O2SAT, lower CBF, and higher pulsatility index compared with those during NAVAhigh. There were no differences in parameters when using low assist levels, except for slightly greater oxygenation in the NAVAlow group. Modifying assist levels during NAVA did not influence hemodynamics, cerebral perfusion, or gas exchange. Targeting the larger V T during PCV resulted in hyperventilation, did not improve oxygenation, and was accompanied by reduced CBF. Similarly, high assist levels during PSV led to mild hyperventilation, resulting in reduced CBF. NAVA's results were independent of the assist level chosen, causing normalized PaCO2, improved oxygenation, and better CBF than did any other mode, with the exception of PSV at low assist levels.

Drug-induced cognitive impairment: Effect of cardiovascular agents

INTRODUCTION

Cardiovascular agents can be associated with a negative effect on cognition, especially in older adults, critically ill people, and those with baseline cognitive impairment. Negative effect on cognition is commonly reported as uncomplicated acute confusion and delirium and, less commonly, chronic cognitive changes due to drug-induced depression and/or dementia.

METHODS

A literature review of case reports, case series, prospective cohort studies, clinical trials, and literature reviews were included in this study. Articles were located using online databases PubMed and Medline using the following keywords: antiarrhythmic agents, anticholinergic burden, antihypertensive agents, beta-blockers, cardiovascular agents, cognitive impairment, delirium, cognition, dementia, depression, digoxin, diuretics, and drug-induced cognitive impairment.

RESULTS

In general, use of all antihypertensives, especially in the case of polypharmacy or inappropriate dosing, can lead to hypotension and/or bradycardia, and thus lead to mental/cognitive status change due to decreased cerebral perfusion. Use of diuretics can be associated with fluid/electrolyte and/or acid-base imbalance, resulting in the onset of confusion and delirium. In addition, cardiovascular agents with central bioavailability, such digoxin and select antiarrhythmics, and antihypertensives may carry a risk for cognitive impairment due to various mechanisms proposed, such as antagonism of central muscarinic acetylcholine receptors, neurotransmission imbalance in the brain, and disruption of physiologic function of sodium/potassium ATPase in the neuronal cells.

DISCUSSION

When dealing with an individual who presents with acute, subacute, and chronic changes in cognitive function, one should perform a thorough medication history as the first step in order to aid in the identification of drug-induced cognitive impairment.

Relationship of cerebral blood flow to aortic-to-pulmonary collateral/shunt flow in single ventricles

OBJECTIVE

Patients with single ventricle can develop aortic-to-pulmonary collaterals (APCs). Along with systemic-to-pulmonary artery shunts, these structures represent a direct pathway from systemic to pulmonary circulations, and may limit cerebral blood flow (CBF). This study investigated the relationship between CBF and APC flow on room air and in hypercarbia, which increases CBF in patients with single ventricle.

METHODS

106 consecutive patients with single ventricle underwent 118 cardiac magnetic resonance (CMR) scans in this cross-sectional study; 34 prior to bidirectional Glenn (BDG) (0.50±0.30 years old), 50 prior to Fontan (3.19±1.03 years old) and 34 3-9 months after Fontan (3.98±1.39 years old). Velocity mapping measured flows in the aorta, cavae and jugular veins. Analysis of variance (ANOVA) and multiple linear regression were used. Significance was p<0.05.

RESULTS

A strong inverse correlation was noted between CBF and APC/shunt both on room air and with hypercarbia whether CBF was indexed to aortic flow or body surface area, independent of age, cardiopulmonary bypass time, Po2 and Pco2 (R=-0.67--0.70 for all patients on room air, p<0.01 and R=-0.49--0.90 in hypercarbia, p<0.01). Correlations were not different between surgical stages. CBF was lower, and APCs/shunt flow was higher prior to BDG than in other stages.

CONCLUSIONS

There is a strong inverse relationship between CBF and APC/shunt flow in patients with single ventricle throughout surgical reconstruction on room air and in hypercarbia independent of other factors. We speculate that APC/shunt flow may have a negative impact on cerebral development and neurodevelopmental outcome. Interventions on APC may modify CBF, holding out the prospect for improving neurodevelopmental trajectory.

TRIAL REGISTRATION NUMBER

NCT02135081.

Cardiovascular risk factors promote brain hypoperfusion leading to cognitive decline and dementia

Heart disease is the major leading cause of death and disability in the world. Mainly affecting the elderly population, heart disease and its main outcome, cardiovascular disease, have become an important risk factor in the development of cognitive decline and Alzheimer's disease (AD). This paper examines the evidence linking chronic brain hypoperfusion induced by a variety of cardiovascular deficits in the development of cognitive impairment preceding AD. The evidence indicates a strong association between AD and cardiovascular risk factors, including ApoE(4), atrial fibrillation, thrombotic events, hypertension, hypotension, heart failure, high serum markers of inflammation, coronary artery disease, low cardiac index, and valvular pathology. In elderly people whose cerebral perfusion is already diminished by their advanced age, additional reduction of cerebral blood flow stemming from abnormalities in the heart-brain vascular loop ostensibly increases the probability of developing AD. Evidence also suggests that a neuronal energy crisis brought on by relentless brain hypoperfusion may be responsible for protein synthesis abnormalities that later result in the classic neurodegenerative lesions involving the formation of amyloid-beta plaques and neurofibrillary tangles. Insight into how cardiovascular risk factors can induce progressive cognitive impairment offers an enhanced understanding of the multifactorial pathophysiology characterizing AD and ways at preventing or managing the cardiovascular precursors of this dementia.

Does depression impact cognitive impairment in patients with heart failure?

Prevalence studies have noted the cooccurrence of cognitive decline and depression in persons with heart failure. Cognitive impairment is associated with significant mortality and deteriorated quality of life, likely due to impairments in memory and executive function, which impact a patient's ability to understand and comply with prescribed treatment plans. This is especially true in complex diseases such as heart failure. Evidence from literature supports the possibility of a pathophysiological relationship between cognitive impairment, depression, and heart failure. Yet, very few studies have sought to investigate this relationship. This paper reviews current literature on the association between depression and cognitive impairment in persons with heart failure and explores possible mechanisms explaining this complex triad.

Cognitive impairment in heart failure

Cognitive impairment (CI) is increasingly recognized as a common adverse consequence of heart failure (HF). Although the exact mechanisms remain unclear, microembolism, chronic or intermittent cerebral hypoperfusion, and/or impaired cerebral vessel reactivity that lead to cerebral hypoxia and ischemic brain damage seem to underlie the development of CI in HF. Cognitive decline in HF is characterized by deficits in one or more cognition domains, including attention, memory, executive function, and psychomotor speed. These deficits may affect patients' decision-making capacity and interfere with their ability to comply with treatment requirements, recognize and self-manage disease worsening symptoms. CI may have fluctuations in severity over time, improve with effective HF treatment or progress to dementia. CI is independently associated with disability, mortality, and decreased quality of life of HF patients. It is essential therefore for health professionals in their routine evaluations of HF patients to become familiar with assessment of cognitive performance using standardized screening instruments. Future studies should focus on elucidating the mechanisms that underlie CI in HF and establishing preventive strategies and treatment approaches.

[Neurological aspects of chronic heart failure]

Chronic heart failure (CHF) is one of the leading causes of hospitalization, morbidity and mortality. Moreover, there is a high rate of neurological as well as neuropsychological comorbidities, namely ischemic stroke, structural brain alterations, cognitive impairment, sleep apnea and possible side-effects of HF medication such as delirium or (intracerebral) hemorrhage. The higher stroke risk in patients with HF increases further with age, concomitant arterial hypertension or atrial fibrillation (AF). In women the stroke risk increases with reduced ejection fraction (EF). In general stroke in HF patients is associated with a poor outcome and higher mortality, which is increased more than 2-fold. Furthermore, approximately 25-80% of all patients with CHF experience cognitive impairments such as decreased attention and concentration, memory loss, diminished psychomotor reaction time and decreased executive functions. Cognitive impairment in patients with HF has been linked to losses in gray matter, (silent) ischemic strokes, decreased cerebral perfusion and higher mortality. Moreover, sleep apnea occurs in more than half of all patients with CHF and reduced EF. However, prospective studies are needed to test whether early detection and optimal treatment of HF reduces the burden of neurological and neuropsychological sequelae.

Usefulness of acute delirium as a predictor of adverse outcomes in patients >65 years of age with acute decompensated heart failure

Delirium is an acute confusional state that is very prevalent in older patients hospitalized with acute decompensated heart failure (ADHF). The association between delirium and ADHF outcome has not been well described. We analyzed 883 consecutive patients >65 years of age admitted with ADHF. Acute delirium was diagnosed based on the Confusion Assessment Method. Delirious patients (total n = 151) had an increased in-hospital all-cause death compared to nondelirious patients (n = 17, 11%, vs n = 45, 6%; adjusted odds ratio [OR] 1.93, 95% confidence interval [CI] 1.07 to 3.48, p = 0.02). Of those surviving to discharge (n = 821), on multivariable logistic regression analysis, delirium was independently associated with increased risk of 30-day (adjusted OR 4.24, 95% CI 2.77 to 6.47, p <0.001) and 90-day (adjusted OR 3.72, 95% CI 2.51 to 5.54, p <0.001) rehospitalizations for ADHF and higher nursing home placement (adjusted OR 2.70, 95% CI 1.59 to 5.30, p <0.001) after adjusting for age, gender, cardiac risk factors, dementia, activities of daily living, instrumental activities of daily living, coronary artery disease, atrial fibrillation, left ventricular ejection fraction, angiotensin-converting enzyme inhibitor and/or angiotensin receptor blocker, β blockers, Charlson co-morbidity index, and other potential confounders. Furthermore, delirium was strongly associated with 90-day all-cause mortality in patients discharged from the hospital (adjusted hazard ratio 2.10, CI 1.53 to 2.88, p <0.0001). In conclusion, acute delirium serves as an important prognostic determinant of in-hospital and posthospital discharge outcomes including increased ADHF readmission risk in older hospitalized patients with ADHF. Thus, delirium plays an important role in the risk stratification and prognosis of patients with ADHF.

The COGNITION study rationale and design: influence of closed loop stimulation on cognitive performance in pacemaker patients

BACKGROUND

Several studies showed the beneficial effect of pacemaker implantation on cognitive performance in patients with bradycardia. But it has never been investigated if patients with chronotropic incompetence may improve their cognitive performance if treated by a rate-adaptive system reacting to mental stress in comparison to the most frequently used accelerometer-driven pacing.

METHODS

The randomized, single-blind, multicenter COGNITION study evaluates if closed loop stimulation (CLS) offers incremental benefit in the speed of cognitive performance and the overall well-being of elderly patients with bradycardia compared with accelerometer-based pacing. Four hundred chronotropically incompetent patients older than 55 years will be randomized 3-6 weeks after implantation to CLS or accelerometer sensor. Follow-up visits are performed after 12 and 24 months. The speed of cognitive performance, which is the underlying function influencing all other aspects of cognitive performance, will be assessed by the number connection test, a standardized psychometric test for the elderly. Secondary endpoints include patient self-assessment of different aspects of health (by visual analogue scales), quality of life (by SF-8 health survey), the incidence of atrial fibrillation (episodes lasting for longer than 24 hours), and the frequency of serious adverse events.

CONCLUSION

In the ongoing COGNITION study, we aim at long-term comparison of two rate-adaptive systems, focusing on the cognitive performance of the patients, which was neglected in the past evaluation of pacemaker sensors.

Neuroimaging and correlates of cognitive function among patients with heart failure

BACKGROUND/AIMS

We purposed to investigate the relationship between cerebral abnormalities detected by magnetic resonance imaging (MRI) and cognitive performance in nondemented outpatients with heart failure (HF).

METHODS

In 58 patients with HF neuropsychological assessment was performed including tests of mental speed, executive functions, memory, language and visuospatial functions. Deep, periventricular and total white matter hyperintensities (WMH), lacunar and cortical infarcts, global and medial temporal lobe atrophy (MTA) were investigated on MRI of the brain. Correlations between MRI findings and the cognitive measures were calculated.

RESULTS

MTA correlated with memory (r = -0.353, p < 0.01), with executive functions (r = -0.383, p < 0.01) and the Mini Mental State Examination (r = -0.343, p < 0.05). Total WMH and deep WMH were found to correlate with depression and anxiety scores, but not with cognitive measures. Age, estimated premorbid intelligence and MTA were independent predictors of diminished cognitive performance.

CONCLUSIONS

In HF patients, MTA was related to cognitive dysfunction, involving memory impairment and executive dysfunction, whereas WMH was related to depression and anxiety.

Chronic ischemia and neurocognition

Cognitive impairment from a major stroke as a consequence of carotid disease is an acknowledged clinical outcome; however, cognitive impairment without major stroke is open to discussion. The three recognized mechanisms for cognitive dysfunction from internal carotid artery are microembolization, white-matter disease, and hypoperfusion. The last has been most difficult to characterize physiologically. In this article, the authors review evidence supporting the existence of chronic ischemia in the brain and its direct impact on cognitive functions. By incorporating the pathophysiology of chronic ischemia into the algorithm of the management of carotid artery disease, we may be able to extend the goals of carotid artery revascularization beyond merely preventing stroke to include preventing or reversing cognitive decline.

Profile of Cognitive Impairment in Chronic Heart Failure

OBJECTIVES

To determine the frequency and pattern of cognitive dysfunction in outpatients with chronic congestive heart failure (CHF) and to identify the corresponding demographic and clinical correlates.

DESIGN

Case-control study.

SETTING

Outpatient clinic in a community hospital.

PARTICIPANTS

Sixty-two outpatients with CHF, 53 controls diagnosed with cardiovascular disease uncomplicated by CHF (cardiac controls), and 42 healthy controls were investigated.

MEASUREMENTS

Neuropsychological assessment included tests of mental speed, executive function, memory, language, and visuospatial function. Composite z-scores for five cognitive domains and mean z-score for overall cognitive performance were computed. The cutoff score to indicate cognitive impairment was defined as the overall healthy participants' cognitive z-score minus 2 standard deviations. Independent demographic and clinical predictors of cognitive impairment were identified using linear regression analysis.

RESULTS

Patients with CHF showed a pattern of general cognitive impairment, including impairment of executive function, memory, language, mental speed, and attention. Twenty-five percent (P=.04) of patients with CHF were classified as cognitively impaired, compared with 15% of the cardiac controls and 4% of the healthy controls. Independent predictors of cognitive impairment in patients with CHF were estimated intelligence, New York Heart Association class, and presence of the apolipoprotein (Apo)E epsilon4 allele.

CONCLUSION

Cognitive dysfunction is relatively common in patients with CHF, with deficits being most prominent in the domains of executive function, memory, language, and mental speed. Disease severity and ApoE genotype are likely to be important determinants for cognitive impairment in patients with chronic CHF.

Cognitive impairment in heart failure: a systematic review of the literature

BACKGROUND

Heart failure (HF) and cognitive impairment are common medical conditions that are becoming increasingly prevalent in the aging Western population. They are associated with frequent hospitalisation and increased mortality, particularly when they occur simultaneously. Evidence from a number of studies suggests that HF is independently associated with impairment in various cognitive domains.

AIMS

This systematic literature review evaluates the relation between cognitive deterioration and heart failure.

METHODS

We searched electronic databases from 1966 to May 2006 for studies that investigated cognitive function in HF patients. Twenty-two controlled studies that met the inclusion criteria were selected for analysis. Study characteristics and data on global cognitive performance, memory scores, psychomotor speed and depression scores were extracted and analysed using the Cochrane Review Manager software.

RESULTS

Pooled analysis shows diminished neuropsychological performance in HF patients, as compared to control subjects. In a pooled sample of 2937 heart-failure patients and 14,848 control subjects, the odds ratio for cognitive impairment was 1.62 (95% confidence interval:1.48-1.79, p<0.0001) among subjects with HF.

CONCLUSION

This review confirms the relationship between HF and cognitive impairment, but it also stresses the need for additional systematic neuropsychological data and adequate neuro-imaging from representative populations of HF patients.

Congestive heart failure and Alzheimer's disease

The increase in average life expectancy is resulting in an increasing prevalence of major invalidating illnesses, such as cardiovascular disease and dementia. Congestive heart failure (CHF) is a chronic, progressive disease representing the advanced stage of cardiac illnesses. Cognitive impairment is known to be a frequent feature of CHF patients. The epidemiologic pictures of mild cognitive impairment (MCI), Alzheimer's disease (AD) and CHF are predicted to worsen with the demographic expansion of the elderly population. Nevertheless, there has been little structured research on cognitive impairment in patients with CHF. This is unfortunate not only because CHF is the leading cause of hospitalization in the elderly and a leading cause of disability and death, but also for important clinical and socioeconomic implications including those related to comorbidity in advanced age and the need to early detect factors which may precipitate the conversion of MCI to AD. In this review, several aspects of the role of CHF in cognitive impairment are evaluated. Owing to the lack of studies focusing on CHF in AD, the pathophysiology of cardiac failure in cognitive impairment is addressed in light of possible preventive strategies against the onset of AD. These include prevention of oxygen radical and peroxynitrite production, supplementation of nitric oxide (NO) donors, as well as the achievement of an adequate antioxidant supply, better if obtained with a targeted and individualized nutritional approach. A systematic neuropsychologic testing of older patients with heart failure is to identify those with early cognitive impairment and promptly establish traditional therapies such as angiotensin converting enzyme (ACE) inhibitors, digoxin or beta-blockers. The neuropsychologic assessment in CHF patients is also fundamental to disclose conditions potentially favoring the onset of cognitive impairment such as depression. Finally, management schemes should include exercise training programs as well as patient and caregiver education.

How do heart disease and stroke become risk factors for Alzheimer's disease?

BACKGROUND

Heart disease and stroke are two of the major leading causes of death and disability in the world. Mainly affecting the elderly population, heart disease and stroke are important risk factors for Alzheimer's disease (AD).

METHODS

This review examines the evidence linking chronic brain hypoperfusion (CBH) produced by several types of heart disease and stroke on the development of AD.

RESULTS

The evidence indicates a strong association between such risk factors as coronary artery bypass surgery (CABG), atrial fibrillation, aortic/mitral valve damage, hypertension, hypotension, congestive heart failure, cerebrovascular-carotid atherosclerosis, and transient ischemic attacks in producing CBH. In people whose cerebral perfusion is already diminished by their advanced age, further cerebral blood flow reductions from heart-brain vascular-related risk factors, seemingly increases the probability of AD. The evidence also suggests that a neuronal energy crisis brought on by a relentless CBH is responsible for protein synthesis defects that later result in the classic AD neurodegenerative lesions such as the formation of excess beta-amyloid plaques and neurofibrillary tangles.

CONCLUSIONS

Knowledge of how heart disease and stroke can progress to AD should provide a better understanding of the physiopathology characteristic of AD and also target more precise therapy in preventing, controlling or reversing this dementia.

Cholinergically Mediated Augmentation of Cerebral Perfusion in Alzheimer's Disease and Related Cognitive Disorders: The Cholinergic-Vascular Hypothesis

The treatment of Alzheimer's disease (AD) with cholinesterase inhibitors (ChEIs) is based on the cholinergic hypothesis. This hypothesis fails to account for the global nature of the clinical effects of ChEIs, for the replication of these effects in other dementias, and for the strong and unpredictable intraindividual variation in response to treatment. These findings may be better explained by the premise that ChEIs primarily act by augmenting cerebral perfusion: the cholinergic-vascular hypothesis. This article will review the evidence from preclinical and clinical investigations on the vascular role of the cholinergic neural system. The clinical relevance of this hypothesis is discussed with respect to its interactions with the vascular and amyloid hypotheses of AD. Implications for treatment are indicated. Finally, we propose that the role of the cholinergic system in neurovascular regulation and functional hyperemia elucidates how the cholinergic deficit in AD contributes to the clinical and pathological features of this disease.

Neurocognitive Function in Patients with Ventricular Assist Devices: A Comparison of Pulsatile and Continuous Blood Flow Devices

The effect of successful ventricular assist device (VAD) implantation on neurocognitive function in terminal heart failure is uncertain. Additionally, the different impact of continuous versus pulsatile blood flow devices is unknown. A total of 29 patients (mean age 53 years), surviving implantation of a ventricular assist device as bridge to transplantation were prospectively followed (continuous flow: Micromed DeBakey, n = 11; pulsatile flow: Thoratec and Novacor, n = 18). Normative data were obtained in 40 age- and sex-matched healthy subjects (mean age 54 years). Neurocognitive function was objectively measured by means of cognitive P300 auditory evoked potentials before operation (baseline), at intensive care unit (ICU) discharge, and at the 8-week and 12-week follow-up. Before implantation of the VAD, cognitive P300 evoked potentials were impaired (prolonged) compared with age- and sex-matched healthy subjects (p < 0.001). After successful VAD implantation, P300 evoked potentials markedly improved compared with before operation (ICU discharge, p = 0.007; 8-week follow-up, p = 0.022; 12-week follow-up, p < 0.0001). Importantly, there was no difference between continuous and pulsatile VADs (before operation, p = 0.676; ICU discharge, p = 0.736; 8-week follow-up, p = 0.911 and 12-week follow-up, p = 0.397; respectively). Nevertheless, P300 peak latencies did not fully normalize at 12-week follow-up compared with healthy subjects (p = 0.012). Successful VAD implantation improves neurocognitive impairment in patients with terminal heart failure. Importantly, this effect is independent of the type of VAD (pulsatile vs. continuous blood flow).

Correlates of cognitive impairment among patients with heart failure: results of a multicenter survey

PURPOSE

Cognitive impairment is an exceedingly prevalent condition among patients with heart failure, independently associated with disability and mortality. However, the determinants of cognitive dysfunction associated with heart failure are still unclear. We assessed the correlates of cognitive impairment among patients with heart failure enrolled in a multicenter pharmacoepidemiology survey.

METHODS

The association with cognition of demographic characteristics, objective tests and measures, medications, and comorbid conditions was assessed in 1511 patients with heart failure who had been admitted to 81 hospitals throughout Italy. Cognitive impairment was defined by a Hodkinson Abbreviated Mental Test score < 7.

RESULTS

According to multivariate logistic regression modeling, age (per each decade: OR = 2.01; 95% confidence interval [CI] 1.72-2.35), the comorbidity score (OR 1.11; 95% CI 1.03-1.20), education (OR 0.88; 95% CI 0.84-0.2), low serum albumin (OR 1.78; 95% CI 1.35-2.34), sodium (OR 1.56; 95% CI 1.06-2.29), and potassium levels (OR 1.58; 95% CI 1.09-2.29), hyperglycemia (OR 1.33; 95% CI 1.02-1.73), anemia (OR 1.38; 95% CI 1.09-1.75), and systolic blood pressure levels > or = 130 mm Hg (OR 0.60; 95% CI 0.37-0.97) were independently associated with cognitive impairment, after adjusting for potential confounders. Among participants with abnormal laboratory findings on admission, restoration of normal glucose, potassium, and hemoglobin levels during hospital stay was associated with improved cognitive performance at discharge.

CONCLUSIONS

Cognitive impairment among patients with heart failure is associated with several comorbid conditions, some of which are potentially treatable. This highlights the key role of comprehensive approach to the assessment and treatment of patients with heart failure.

Brain versus lung: hierarchy of feedback loops in single-ventricle patients with superior cavopulmonary connection

BACKGROUND

CO2 vasodilates and O2 vasoconstricts the cerebral vascular bed; the opposite is true in the lungs. When the brain and lungs are connected exclusively in series, which feedback loop predominates is unknown. The circulation of the superior cavopulmonary connection (SCPC) provides a unique physiology to answer this question.

METHODS AND RESULTS

To determine cerebral and pulmonary blood flow and to establish the hierarchy of cerebral and pulmonary feedback mechanisms, 12 intubated, ventilated, single-ventricle patients in SCPC physiology (age 2.2+/-0.5 years) underwent magnetic resonance imaging velocity mapping of their jugular veins and aorta in room air, hypercarbia, and 100% O2. Flows in these vessels and arterial blood gases were measured. With 22+/-6 torr CO2 (Pco2) increased from 40 to 63 mm Hg, P<0.01), flow to the brain and lungs increased (1.5 to 2.7 L/min per m2, P=0.0003), Po2 improved (48 to 60 mm Hg, P=0.0004), and cardiac index increased (4.3 to 5.4 L/min per m2, P=0.0003). The increased cardiac index accounted for the increased cerebral and pulmonary blood flow (R=0.73, P=0.02) and cerebral O2 transport increased by 80% (P=0.0005) while preserving body O2 delivery. Hyperoxia did not change cerebral and pulmonary blood flow; Po2 increased 94% (P=0.01).

CONCLUSIONS

The cerebral CO2 feedback loop predominates over the pulmonary one when they directly compete with each other. CO2 has a major impact on flow distribution whereas O2 has little impact. Increased CO2 improves cerebral oxygenation in SCPC patients. This may provide a clue in determining neurological sequelae in SC physiology and may influence timing of Fontan completion.

Spontaneous subarachnoid hemorrhage and serious cardiopulmonary dysfunction--a systematic review

INTRODUCTION

: The association between the degree of neurological deficit and cardiopulmonary dysfunction in patients with spontaneous subarachnoid hemorrhage (SAH) is poorly understood.

METHOD

A systematic search (MEDLINE, bibliographies, to 9.2004) was performed for prospective studies (any architecture; > or = 10 patients with SAH), reporting on neurological deficit and cardiopulmonary dysfunction. Neurological deficit was graded according to the Hunt-Hess or Botterell scores as minimal (1 or 2 points), moderate (3), or severe (4 or 5), and tested for an association with cardiopulmonary dysfunction (Chi-square test).

RESULTS

Relevant data came from two randomized trials, four case control studies, and 31 uncontrolled series. In eight studies (386 patients), ECG abnormalities were found in 32% of patients with minimal, 55% with moderate, and 58% with severe neurological deficit (P < 0.0001). In six studies (135), echocardiographic abnormalities were found in 4% of patients with minimal, 30% with moderate, and 52% with severe neurological deficit (P = 0.0001). In two trials (63), creatinine phosphoskinase was increased in 18% of patients with minimal, 71% with moderate, and 100% with severe neurological deficit (P < 0.0001). In three trials (309), troponin-I was increased in 10% of patients with minimal, 20% of patients with moderate, and 46% with severe neurological deficit (P < 0.0001). In five trials (163), pulmonary edema was found in 4% of patients with minimal, 12% with moderate, and 35% with severe neurological deficit (P < 0.0001). Seventeen studies reported on mortality; 26% of the patients died, 80% of deaths were directly related to SAH.

CONCLUSIONS

In patients with spontaneous SAH, cardiopulmonary dysfunction is more likely to occur with increasing neurological deficit.

Use of angiotensin-converting enzyme inhibitors and variations in cognitive performance among patients with heart failure

AIMS

Cognitive dysfunction is a prevalent condition among patients with heart failure, and is independently associated with disability and mortality. Angiotensin-converting enzyme (ACE)-inhibitors might increase cerebral blood flow in subjects with heart failure. Our aim was to assess whether starting treatment with ACE-inhibitors might improve cognition in patients with heart failure.

METHODS AND RESULTS

Analyses involved 12 081 subjects, 1220 of whom had a verified diagnosis of heart failure, enrolled in a multi-centre pharmaco-epidemiology survey. None of these participants received ACE-inhibitors before hospitalization. Among participants with heart failure, cognitive performance improved in 30% of 446 participants who started ACE-inhibitors, but only in 22% of remaining patients (P=0.001). Among participants without heart failure, cognition improved in 19% of those receiving ACE-inhibitors, and in 18% of untreated patients (P=0.765). Use of ACE-inhibitors among patients with heart failure was associated with improving cognition (odds ratio=1.57; 95% CI 1.18-2.08) also in the multivariable regression modelling, independently of baseline or discharge blood pressure levels. The probability of improving cognitive performance was higher for dosages above the median values, as compared with lower doses (odds ratios=1.90 and 1.42; P for trend=0.001), and increased with duration of treatment (odds ratios for the lower, middle, and upper tertiles=1.25, 1.34, and 1.59; P for trend=0.007).

CONCLUSION

Treatment with ACE-inhibitors might selectively improve cognitive performance in patients with heart failure. However, up-titration of these agents might be required to yield the greatest benefit.

The effects of cognitive impairment on mortality among hospitalized patients with heart failure

PURPOSE

Cognitive impairment is a common, potentially reversible condition among older patients with heart failure. Because cerebral metabolic abnormalities have been associated with reduced survival in younger patients with advanced heart failure, we assessed the effect of cognitive impairment on the survival of older patients with heart failure.

METHODS

The association between cognitive dysfunction and in-hospital mortality was assessed in 1113 patients (mean [+/- SD] age, 78 +/- 9 years) who had been admitted for heart failure to 81 hospitals throughout Italy. One-year mortality was assessed in 968 patients with heart failure (age, 76 +/- 10 years) participating in the same study. Cognitive impairment was defined as a Hodkinson Abbreviated Mental Test score <7.

RESULTS

In-hospital death occurred in 65 (18%) of the 357 participants with cognitive impairment and in 26 (3%) of the 756 patients with normal cognition (P <0.0001). Out-of-hospital mortality was 27% (51/191) among patients with cognitive impairment and 15% (115/777) among other participants (P <0.0001). In multivariate Cox regression models, decreasing levels of cognitive functioning were associated with increasing in-hospital mortality; cognitive impairment was associated with an almost fivefold increase in mortality (relative risk = 4.9; 95% confidence interval: 2.9 to 8.3) after adjusting for several potential confounders.

CONCLUSION

Cognitive impairment is an independent prognostic marker in older patients with heart failure. Assessment of cognitive functioning, even by simple screening tests, should be part of the routine assessment of elderly patients with heart failure.

Well-being and cerebral oxygen saturation during acute heart failure in humans

Cerebral symptoms and near-infrared spectrophotometry-determined cerebral oxygen saturation (ScO2) were followed in patients treated for normotensive acute congestive heart failure. The reproducibility and normal range for ScO2 were established from 39 resting subjects without cardio-respiratory disease: the ScO2 ranged from 55 to 78% with a coefficient of variation for triple determination of 6%. Patients rated cerebral symptoms on a scale with end-points of 0 (best) and 10 (worst). In eight patients with acute heart failure, arterial oxygen tension increased during decongestive treatment, from 9.1 (4.9-10) to 10.4 kPa (7.3-17); median with range, as did arterial oxygen saturation, from 94 (48-97) to 97% (87-99) (P<0.02), whereas the mean arterial pressure, heart rate and arterial carbon dioxide tension remained unchanged. The cerebral symptom score improved from 8 (3-10) to 1 (1-9) and the ScO2 increased from 34 (20-58) to 50% (19-91) (P<0.02). A ninth patient presented with a silent but massive myocardial infarction: she was cerebrally obtunded with a ScO2 of 18% and soon died. In patients with normotensive acute heart failure and cerebral symptoms, cerebral oxygen saturation is low, and during successful treatment ScO2 increases with the well-being of the patient.

Cyclosporine may affect improvement of cognitive brain function after successful cardiac transplantation

BACKGROUND

The effects of cardiac transplantation on cognitive brain function are uncertain.

METHODS AND RESULTS

We measured cognitive brain function and quality of life in out-of-hospital cardiac transplant candidates (n = 55; ejection fraction, 19.9%; age, 54.8 years [means]). After transplantation, the patients were serially reevaluated at 4 months (n = 25) and at 12 months (n = 19). Brain function was measured objectively by cognitive P300 evoked potentials. Additionally, standard psychometric tests (Trail Making Test A, Mini-Mental State Examination, and Profile of Mood State test) were performed. Cognitive P300 evoked potentials were impaired in cardiac transplant candidates (359 ms, recorded at vertex) compared with 55 age- and sex-matched healthy subjects (345 ms, P < .01). Trail Making Test A was also abnormal (45 versus 31 seconds in 55 healthy subjects, P < .01). After transplantation, P300 measures were normalized at 4 months (345 ms, P < .05 versus before transplantation) but declined again at 12 months (352 ms, P = NS versus before transplantation). Stepwise multiple regression analysis revealed that cumulative cyclosporine dosage was the only predictor of individual cognitive brain function 4 months (753 mg/kg body wt, P < .05) and 12 months (2006 mg/kg body wt, P < .01) after transplantation, respectively.

CONCLUSIONS

Objective cognitive P300 auditory evoked potential measurements indicate that cognitive brain function is significantly impaired in patients suffering from stable end-stage heart failure. Successful cardiac transplantation is effective to fully normalize impaired brain function. Subsequent relative long-term decline of cognitive brain function after successful cardiac transplantation is strongly suggested to be related to cumulative cyclosporine neurotoxicity.