Cerebral microemboli during left heart catheterization

Acute Myocardial Infarction and Risk of Cognitive Impairment and Dementia: A Review

Cognitive impairment (CI) shares common cardiovascular risk factors with acute myocardial infarction (AMI), and is increasingly prevalent in our ageing population. Whilst AMI is associated with increased rates of CI, CI remains underreported and infrequently identified in patients with AMI. In this review, we discuss the evidence surrounding AMI and its links to dementia and CI, including pathophysiology, risk factors, management and interventions. Vascular dysregulation plays a major role in CI, with atherosclerosis, platelet activation, microinfarcts and perivascular inflammation resulting in neurovascular unit dysfunction, disordered homeostasis and a dysfunctional neurohormonal response. This subsequently affects perfusion pressure, resulting in enlarged periventricular spaces and hippocampal sclerosis. The increased platelet activation seen in coronary artery disease (CAD) can also result in inflammation and amyloid-β protein deposition which is associated with Alzheimer's Dementia. Post-AMI, reduced blood pressure and reduced left ventricular ejection fraction can cause chronic cerebral hypoperfusion, cerebral infarction and failure of normal circulatory autoregulatory mechanisms. Patients who undergo coronary revascularization (percutaneous coronary intervention or bypass surgery) are at increased risk for post-procedure cognitive impairment, though whether this is related to the intervention itself or underlying cardiovascular risk factors is debated. Mortality rates are higher in dementia patients with AMI, and post-AMI CI is more prevalent in the elderly and in patients with post-AMI heart failure. Medical management (antiplatelet, statin, renin-angiotensin system inhibitors, cardiac rehabilitation) can reduce the risk of post-AMI CI; however, beta-blockers may be associated with functional decline in patients with existing CI. The early identification of those with dementia or CI who present with AMI is important, as subsequent tailoring of management strategies can potentially improve outcomes as well as guide prognosis.

Silent cerebral emboli following percutaneous closure of atrial septal defect in pediatric patients: a diffusion-weighted MRI study

PURPOSE

The aim of this prospective study was to investigate the incidence of silent cerebrovascular embolic events associated with percutaneous closure of atrial septal defect (ASD) in pediatric patients.

METHODS

A total of 23 consecutive pediatric patients (mean age, 10.4±3.8 years; range, 4-17 years) admitted for transcatheter closure of ASD were recruited in the study. The patients were scanned with a 1.5 Tesla clinical scanner. Two cranial magnetic resonance imaging (MRI) examinations were acquired before the procedure and within 24 hours following the catheterization. MRI included turbo spin-echo fluid-attenuated inversion recovery (FLAIR) sequence and diffusion-weighted imaging technique with single-shot echo-planar spin-echo sequence. The transcatheter closure of ASD was performed by three expert interventional cardiologists. Amplatzer septal occluder device was implemented for the closure of the defect. No contrast medium was administered in the course of the procedure.

RESULTS

None of the patients had diffusion restricted cerebral lesions resembling microembolic infarctions on postprocedural MRI. Preprocedural MRI of two patients revealed nonspecific hyperintense white matter lesions on FLAIR images with increased diffusion, which were considered to be older ischemic lesions associated with previously occurred paradoxical embolism.

CONCLUSION

The current study suggests that percutaneous closure of the ASD, when performed by experienced hands, may be free of cerebral microembolization in pediatric patients. However, due to the relatively small sample size, further studies with larger patient groups are needed for the validation of our preliminary results.

Incidence and risk factors of cerebrovascular events following cardiac catheterization

Background

One of the most daunting complications of cardiac catheterization is a cerebrovascular event (CVE). We aimed to assess the real‐life incidence, etiology, and risk factors of cardiac catheterization‐related acute CVEs in a large cohort of patients treated in a single center.

Methods and Results

We undertook a retrospective analysis of 43 350 coronary procedures performed on 30 907 procedure days over the period 1992‐2011 and compared patient and procedural characteristics of procedures complicated by CVEs with the remaining cohort. CVEs occurred in 47 cases: 43 were ischemic, 3 intracerebral hemorrhages, and 1 undetermined. The overall CVE rate was 0.15%, with percutaneous coronary intervention (PCI) and diagnostic coronary angiography rates 0.23% and 0.09%, respectively. Using a forward stepwise multivariate logistic regression model including patient demographic and procedural characteristics, a total of 5 significant predictors were defined: prior stroke (OR=15.09, 95% CI [8.11 to 28.08], P<0.0001), presence of coronary arterial thrombus (OR=2.79, 95% CI [1.25 to 6.22], P=0.012), age >75 years (OR=3.33, 95% CI [1.79 to 6.19], P<0.0001), triple vessel disease (OR=2.24, 95% CI [1.20 to 4.18], P=0.011), and performance of intervention (OR=2.21, 95% CI [1.12 to 4.33], P=0.021). An additional analysis excluded any temporal change of CVE rates but demonstrated a significant increase of all high‐risk patient features.

Conclusion

In a single‐center, retrospective assessment over nearly 20 years, cardiac catheterization‐related CVEs were very rare and nearly exclusively ischemic. The independent predictors for these events were found to be the performance of an intervention and those associated with increased atherosclerotic burden, specifically older age, triple vessel disease, and prior stroke. The presence of intracoronary thrombus appears also to raise the risk of procedure‐related CVE.

Cognitive function in patients undergoing coronary angiography

OBJECTIVE

To measure cognition in patients before and after coronary angiography.

DESIGN

Prospective observational cohort study.

SETTING

University teaching hospital.

PATIENTS

56 patients presenting for elective coronary angiography.

MAIN OUTCOME MEASURES

Computerised cognitive test battery administered before coronary angiography, before discharge from hospital and 7 days after discharge. A matched healthy control group was used as a comparator.

RESULTS

When analysed by group, coronary angiography patients performed worse than matched controls at each time point. When the cognitive change was examined for each individual, of the 48 patients tested at discharge, 19 (39.6%) were classified as having a new cognitive dysfunction, and of 49 patients tested at day 7, six (12.2%) were classified as having a new cognitive dysfunction.

CONCLUSIONS

The results confirm that cognitive function is decreased in patients who have cardiovascular disease. Furthermore, coronary angiography may exacerbate this impaired cognition in some patients.

Occurrence and clinical impact of microembolic signals during or after cardiosurgical procedures

BACKGROUND AND PURPOSE

Microembolic signals (MESs) are detectable within the transcranial Doppler frequency spectrum downstream from vascular atherothrombotic or cardiothrombotic lesions. A frequent occurrence of MESs has also been shown during bypass surgery or after mechanical valve implantation. We sought to compile the knowledge on MES prevalence, the clinical impact of these cardiogenic MESs, and microemboli composition.

SUMMARY OF REVIEW

We performed a systematic MEDLINE search and summarized the currently available literature about MESs during or after cardiosurgical procedures for this state-of-the-art report.

CONCLUSIONS

The nature of cardiogenic MESs is heterogeneous, and their prevalence is highly variable, reflecting their different origin from a broad spectrum of cardiosurgical conditions. The occurrence and number of MESs during cardiac catheterization and percutaneous coronary angioplasty seem to have a clinical impact but need to be explored further. In patients with prosthetic heart valves, in those with left ventricular assist devices, and during cardiac surgery, the occurrence of MESs has an important clinical impact, and MES monitoring has proven its reliability. Although the data encourage intensifying MES detection in cardiac disorders, their heterogeneous nature does not yet allow the use of MESs as a general surrogate parameter for neuronal damage or cardial thromboembolic risk.

Transcranial Doppler Detection of Microembolic Signals During Pulmonary Vein Antrum Isolation: Implications for Titration of Radiofrequency Energy

BACKGROUND

Cerebrovascular events are an important complication during pulmonary vein antrum isolation (PVAI). Microembolic signals (MES) have been associated with stroke and neurological impairment. However, the incidence of MES during PVAI, and their relationship to microbubble formation and radiofrequency (RF) parameters are unknown.

OBJECTIVES

We sought to assess the relationship between MES, microbubble detection, and neurological outcome and the impact of RF titration strategy on these parameters.

METHODS

We studied 202 patients in two groups undergoing PVAI using an intracardiac echocardiography (ICE)-guided technique. MES were detected by transcranial Doppler (TCD) using insonation of the middle cerebral arteries. The number of microbubbles on ICE were qualitatively labeled as FEW, MODERATE, and SHOWER. In group I (n = 107), RF output was titrated to avoid microbubble formation and in group II (n = 95), standard power-limited RF output was used.

RESULTS

TCD detected MES in all 202 patients during PVAI with an average of 1,793 +/- 547 per patient; 90% were detected during left atrial ablation. Over 85% of MES occurred after microbubbles. Group I patients had significantly lower numbers of MES (1,015 +/- 438 per patient) compared to group II patients (2,250 +/- 864 per patient) (P < 0.05). Group II also had a 3.1% incidence of acute neurological complications versus 0.9% in group I (P = 0.10). Patients with clinical events had significantly higher numbers of MES. There were no significant correlations between RF power, temperature, or impedence and MES number.

CONCLUSIONS

MES directly correlate to the amount of microbubble formation on ICE, and may result in cerebroembolic complications. Titration of RF according to microbubble formation by ICE during PVAI may be important for minimizing the occurrence of MES and possibly acute neurological complications.

Cerebral emboli during left heart catheterization may cause acute brain injury

AIMS

Left heart catheterization carries a risk for cerebral complications. The aims of this prospective study were to determine the frequency and composition of catheterization-related cerebral microemboli and to detect cerebral morphological changes and acute cognitive impairment due to catheterization.

METHODS AND RESULTS

Forty-seven unselected patients undergoing elective left heart catheterization, either by transradial or by transfemoral access, were monitored for cerebral microemboli using multifrequency transcranial Doppler. Cerebral magnetic resonance imaging (MRI) with diffusion-weighted imaging sequences and neuropsychological assessments were carried out on the day before and the day after catheterization. A median number of 754 cerebral microemboli were detected: 92.1% were gaseous and 7.9% were solid. New cerebral lesions were observed in 15.2% of the transradial, but none of the transfemoral, catheterization patients (P=0.567). These lesions were significantly associated with a higher number of solid microemboli (P=0.016) and a longer fluoroscopy time (P=0.039). There was also a significantly higher number of solid microemboli during transradial than during transfemoral catheterization (P=0.012). Cognitive impairment following the investigations was associated with the degree of pre-catheterization cerebral MRI injury (P=0.03).

CONCLUSION

During left heart catheterization, cerebral microemboli, especially those which are solid, may damage the brain. Cardiac catheterization may therefore pose a greater risk for the brain than previously acknowledged.

Characterization of ultrasound-detected cerebral microemboli in patients undergoing cardiac catheterization using an in vitro middle cerebral artery model

Cerebral embolization has been documented as one of the complications of diagnostic heart catheterization by transcranial Doppler (TCD). This study aimed to evaluate our hypothesis that the nature of embolic signals involved in different stages of catheter manipulation may be distinct. TCD-detected cerebral emboli occurring at different phases of cardiac catheterization were registered and differentiated by comparing their acoustic signatures with the Doppler signals generated from clinically frequently encountered embolic materials in an in vitro middle cerebral artery model. We found that there was a significant difference in embolic signal intensity and duration between different phases of cardiac catheterization. Our data suggest that different types of emboli may be involved in different phases of the catheterization. Cathet Cardiovasc Intervent 2001;53:323-330.

Cerebral microembolism detected by transcranial Doppler during cardiac procedures

BACKGROUND AND PURPOSE

Cerebral embolism with clinical sequelae may rarely complicate cardioversion and cardiac catheterization. Transcranial Doppler sonography has recently been introduced to monitor microemboli entering the middle cerebral artery in cardiac and carotid surgery. We therefore used this technique to evaluate the risk of asymptomatic embolism during common cardiac procedures.

METHODS

Patients were monitored by transcranial Doppler while undergoing direct current cardioversion (n=15) and cardiac catheterization (n=17).

RESULTS

Microemboli were detected in all patients having cardiac catheterization but in only 1 patient after cardioversion.

CONCLUSIONS

Microembolism occurred frequently during cardiac catheterization and rarely during cardioversion. It is not yet known whether this has clinical relevance.