Reduction of Cerebral Emboli: In vitro Study with a Novel Cerebral Embolic Protection Device

Aim

To assess the efficacy of the TriGUARD 3™, a novel cerebral embolic protection (CEP) device in reducing cerebral embolization by deflecting embolic debris away from the cerebral circulation using a quantitative in vitro model.

Methods and Results

This in vitro study assessed the ability of a cerebral embolic protection device to deflect embolic debris, by measuring the percent of particles and air bubbles, 200 µm and 300 µm in size, from entering the cerebral circulation compared to unprotected controls. A 3D printed silicone model of the ascending aorta, the aortic arch with its three major cerebral arteries and the descending aorta was connected to a custom-made simulator that mimics physiological pulsatile flow patterns of the left ventricle. Comparative analyses were used to assess the efficacy of the cerebral embolic protection device to deflect particles and air bubbles away from the major cerebral arteries. The percent of particles and air bubbles entering the major cerebral arteries was significantly lower with cerebral embolic protection compared to unprotected controls (p<0.0001). Cerebral protection resulted in 97.4–100% reduction in air bubble counts, and 97.4–97.8% reduction in particle counts compared to unprotected controls.

Conclusion

This in vitro study used simulated physiologic flow conditions in an aortic arch model to demonstrate >97% efficacy of the TriGUARD 3 CEP device, in reducing cerebral embolization of particulate and air bubbles of 200 µm to 300 µm in size.

Radiofrequency-intravascular ultrasound assessment of lesion coverage after angiography-guided emergent percutaneous coronary intervention in patients with non-ST elevation myocardial infarction

Using radiofrequency-intravascular ultrasound (VH-IVUS), we have previously demonstrated that in 50% of patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention with optimal angiographic result, the stent does not fully cover the whole VH-IVUS-derived thin-cap fibroatheroma (VH-TCFA) related to the culprit lesion. Presently, we set out to extend these findings to 20 patients with non-STEMI with Thrombolysis In Myocardial Infarction flow 3 in the infarct-related artery before intervention who were then treated with angiography-guided direct stent implantation. The lesion was imaged with VH-IVUS before and after intervention, but the results were blinded to the operator. Plaque rupture site was identified in 8 lesions (40%), all proximal to the minimum lumen area (MLA) site. The maximum necrotic core site was found proximal to MLA in 18 lesions and at the MLA in 2 lesions. Although the plaque rupture site was fully covered with the stent in all lesions, an uncovered VH-TCFA was found in 7 lesions (35%), 4 in the proximal reference segment, 1 in the distal reference segment, and 2 in both the proximal and distal reference segments. In conclusion, in 35% of patients with non-STEMI undergoing angiography-guided emergent percutaneous coronary intervention, the stent does not fully cover a VH-TCFA related to the culprit lesion.

Virtual histology-intravascular ultrasound assessment of lesion coverage after angiographically-guided stent implantation in patients with ST Elevation myocardial infarction undergoing primary percutaneous coronary intervention

An occlusion or severe stenosis (angiographic culprit lesion) of the infarct-related artery is frequently located at the site of the maximum thrombus burden, whereas the origin of the plaque rupture (the true culprit) can be situated proximal or distal to it. The aim of this study was to examine stent coverage of true culprit lesions in 20 patients who underwent primary percutaneous coronary intervention and had Thrombolysis In Myocardial Infarction (TIMI) grade 3 flow restored in the infarct-related artery by angiographically guided direct stenting. Images of lesions were obtained using virtual histology-intravascular ultrasound before and after intervention (blinded to the operator). Plaque rupture sites were identified by intravascular ultrasound in 12 lesions (60%), 11 proximal and 1 distal to the minimum luminal area (MLA). Maximum necrotic core sites were found proximal to the MLA in 16 lesions, at the MLA in 3 lesions, and distal to the MLA in 1 lesion. Plaque rupture sites were fully covered by stents in 11 lesions. Virtual histology-intravascular ultrasound-derived thin-cap fibroatheroma longitudinal geographic misses were found in 10 lesions, 7 in the proximal reference segment and in 3 patients in the proximal and distal reference segments. In conclusion, in about 50% of patients who undergo primary percutaneous coronary intervention for ST-segment elevation myocardial infarction with optimal angiographic results, the stent does not fully cover the maximum necrotic core site related to the culprit lesion.

Tissue characterisation of atherosclerotic plaque in coronary artery bifurcations: an intravascular ultrasound radiofrequency data analysis in humans

AIMS

To investigate tissue characteristics of atherosclerotic plaques in coronary artery bifurcations.

METHODS AND RESULTS

Using a global virtual histology registry, geometric and compositional characteristics of plaque in three segments (proximal, distal, and at the bifurcation) of coronary bifurcation sites were analysed with intravascular ultrasound radiofrequency data (RFD) analysis. A total of 256 bifurcation sites were analysed: left main (LM)-left anterior descending artery (LAD), 41; LAD-diagonal artery, 128; left circumflex artery-obtuse marginal artery, 34; and right coronary artery-acute marginal artery, 53. The plaque+media (P+M) burden was larger in the distal segments of LM-LAD bifurcation sites than in the proximal and at the bifurcation segments (46.55±12.08% vs. 40.40±11.76%, 41.15±11.01%, p<0.001). The % necrotic core (NC) and % dense calcium (DC) at the bifurcation and distal segments of LM-LAD bifurcation sites was significantly greater than in the proximal segments (6.75±5.09%, 7.36±6.01% vs. 4.89±4.78%, p<0.05, and 3.31±2.87%, 3.73±3.28% vs. 1.89±2.10%, p<0.001). In contrast, P+M burden, % NC and % DC in the proximal segments of non-LM bifurcation sites was significantly greater than at the bifurcation and distal segments (49.41±12.12% vs. 45.34±11.21%, 46.80±10.68% / 8.08±6.21% vs. 6.47±5.11%, 6.28±5.05% / 4.57±4.67% vs. 3.38±3.44%, 3.55±3.74%, all p<0.001).

CONCLUSIONS

The results demonstrate that heterogeneous nature of coronary atherosclerosis at coronary bifurcations according to their segments and anatomical locations (LM-LAD vs. non-LM bifurcations). The further investigation for the clinical efficacy of the RFD analysis on bifurcation sites are warranted.

Diabetes mellitus is associated with plaque classified as thin cap fibroatheroma: an intravascular ultrasound study

We compared measures of ID coronary atherosclerosis between diabetic and non-diabetic patients enrolled in a prospective multinational IVUS registry. The region of interest was the most diseased 10 mm segment of a single coronary artery. Coronary plaque was quantified using greyscale IVUS and further classified by phenotype (ID-adaptive intimal thickening, ID-pathological intimal thickening, ID-TCFA, ID-fibroatheroma, or ID-fibrocalcific) using VH-IVUS. There was a non-significant trend for greater total plaque volume in diabetic (n=191) compared with non-diabetic (n=584) patients (94.8 vs. 88.1 mm(3), p=0.36, adjusted for multiple comparisons). There was a greater proportion of ID-TCFA among diabetic patients (21.6 vs. 13.6%, p=0.01 after adjustment for multiple comparisons; p=0.08 following multivariable adjustment for age and clinical demographics), while differences in pathological intimal thickening, fibroatheroma and fibrocalcific plaque were not significant between groups. ID-TCFA was more common in the most diseased 10 mm segment of diabetic than in non-diabetic coronary arteries. Multivariable adjustment demonstrated age and possibly the presence of diabetes to be independent predictors of ID-TCFA.

Synergistic effect of cardiovascular risk factors on necrotic core in coronary arteries: a report from the global intravascular radiofrequency data analysis registry

OBJECTIVES

This study explored whether an individual or a cluster of risk factors affects the extent of necrotic core (NC) assessed by intravascular ultrasound (IVUS) radiofrequency data (RFD) analysis.

BACKGROUND

Several systemic diseases contribute to the development of coronary artery disease.

METHODS

The Global Intravascular Radiofrequency Data Analysis Registry was a prospective, multicenter, nonrandomized database that enrolled 990 patients with coronary artery disease in whom 1 major coronary artery was imaged by IVUS-RFD. For the multivariable analysis, the population was divided into 4 classes: young women, young men (both <or=62 years), old women, and old men (>62 years). Mean NC area was categorized as 1: top quartile (>or=0.62 mm(2)) or as 0: lower 3 quartiles.

RESULTS

Young patients had less NC compared with older patients (0.40 +/- 0.36 mm(2) of NC vs. 0.50 +/- 0.46 mm(2) in old patients, p = 0.0007). Nondiabetic patients had less NC than diabetic patients (0.43 +/- 0.41 mm(2) of NC vs. 0.51 +/- 0.44 mm(2) in diabetic patients, p = 0.02). The NC area was lower in normotensive patients (0.40 +/- 0.36 mm(2)) than in hypertensive patients (0.48 +/- 0.44 mm(2)) (p = 0.02). In the bivariate analysis, age, hypertension, diabetes, and prior coronary artery bypass graft were statistically significant, however in logistic regression analysis, only age (odds ratio [OR]: 1.023, 95% confidence interval [CI]: 1.009 to 1.037, p = 0.001) and diabetes (OR: 1.636, 95% CI: 1.174 to 2.279, p = 0.004) remained statistically significant. In a per-class logistic regression analyses including only diabetes as covariate, the OR in young women was 2.1 (95% CI: 0.77 to 6.0, p = 0.14), in young men the OR was 1.6 (95% CI: 0.90 to 2.7, p = 0.11), in old women the OR was 2.3 (95% CI: 1.09 to 4.9, p = 0.03), and in old men the OR was 1.6 (95% CI: 0.96 to 2.7, p = 0.07). Further, when only patients with diabetes and hypertension were included, young men (OR: 2.0, p = 0.041), old women (OR: 3.04, p = 0.046), and old men (OR: 2.2, p = 0.025) were significant.

CONCLUSIONS

Individually and collectively, age and diabetes mellitus are associated with an increase in NC by IVUS-RFD analysis.

Interventions aimed at improving immunization rates

BACKGROUND

Immunization rates for children and adults are rising, but coverage levels have not reached national goals. As a result of low immunization rates, vaccine-preventable diseases still occur. In an era of increasing complexity of immunization schedules, rising expectations about the performance of primary care, and large demands on primary care physicians, it is important to understand and promote interventions that work in primary care settings to increase immunization coverage. A common theme across immunization programs in all nations involves the challenge of determining the denominator of eligible recipients (e.g., all children who should receive the measles vaccine), and identifying the best strategy to ensure high vaccination rates. Strategies have focused on patient-oriented interventions (e.g., patient reminders), provider interventions, and system interventions. One intervention strategy involves patient reminder/recall systems.

OBJECTIVES

Assess the effectiveness of patient reminder/recall systems in improving immunization rates, and compare the effects of various types of reminders in different settings or patient populations.

SEARCH STRATEGY

A systematic search was performed using MEDLINE (1966-1998) and 4 other bibliographic databases: EMBASE, PsychINFO, Sociological Abstracts, and CAB Abstracts. Authors also performed a search of EPOC in April 2001 to update the review. Two authors reviewed the lists of titles and abstracts, and used the inclusion criteria to mark potentially relevant articles for full review. The reference lists of all relevant articles and reviews were back searched for additional studies. Publications of abstracts, proceedings from scientific meetings, and files of study collaborators were also searched for references.

STUDY DESIGN

Randomized controlled trials (RCT), controlled before and after studies (CBA), and interrupted time series (ITS) studies written in English.

TYPES OF PARTICIPANTS

Health care personnel who deliver immunizations and children (birth to 18 years) or adults (18 years and up) who receive immunizations in any setting. Types of interventions: Any intervention that falls within the Effective Practice and Organization of Care Group (EPOC) scope and that includes patient reminder and/or recall in at least one arm of the study. Types of outcome measures: Immunization rates, or the proportion of the target population up-to-date on recommended immunizations. Outcomes were acceptable for either individual vaccinations (e.g., influenza vaccination) or standard combinations of recommended vaccinations (e.g., all recommended vaccinations by a specific date or age).

DATA COLLECTION

Each study was read independently by two reviewers. Disagreements between reviewers were resolved by a formal reconciliation process to achieve consensus.

ANALYSIS

Results are presented for individual studies as relative rates for randomized controlled trials, and as absolute changes in percentage points for controlled before and after studies. Pooled results were presented using the random effects model.

MAIN RESULTS

Patient reminder/recall systems were effective in improving immunization rates in 33 of 41 included studies, irrespective of baseline immunization rates, patient ages, type of setting, or type of vaccination. Increases in immunization rates due to reminders were in the range of 5 to 20 percentage points. Reminders were effective for childhood vaccinations (OR=2.02, 95% CI =1.49,2.72), childhood influenza vaccinations (OR=4.19, 95% CI =2.07,8.49), adult pneumococcus or tetanus (OR=5.14, 95%CI = 1.21, 21.8), and adult influenza vaccinations (OR=2.29, 95%CI = 1.69, 3.10). While reminders were most effective in academic settings (OR = 3.33, 95% CI = 1.98, 5.58), they were also highly effective in private practice settings (OR=1.79, 95% CI = 1.45, 2.22) and public health clinics (OR = 2.09, 95% CI = 1.42, 3.07). All types of reminders were effective (postcards, letters, telephone or autodialer calls), with telephone being the most effective but most costly.

REVIEWER'S CONCLUSIONS

Patient reminder/recall systems in primary care settings are effective in improving immunization rates.

Resistance of Streptococcus pneumoniae to deformylase inhibitors is due to mutations in defB

Resistance to peptide deformylase inhibitors in Escherichia coli or Staphylococcus aureus is due to inactivation of transformylase activity. Knockout experiments in Streptococcus pneumoniae R6x indicate that the transformylase (fmt) and deformylase (defB) genes are essential and that a def paralog (defA) is not. Actinonin-resistant mutants of S. pneumoniae ATCC 49619 harbor mutations in defB but not in fmt. Reintroduction of the mutated defB gene into wild-type S. pneumoniae R6x recreates the resistance phenotype. The altered enzyme displays decreased sensitivity to actinonin.

Measuring the process of preventive service delivery in primary care practices for children

BACKGROUND

Children may fall behind on preventive services because they do not receive needed services at the time of an office visit (a missed opportunity). However, methods are needed to measure problems in the care delivery process that lead to missed opportunities. We developed a method to examine the key steps in the preventive service delivery process and identify problems; we assessed the feasibility and validity of the method in primary care practices for children.

METHODS

Using 3 data collection methods, we measured key steps in the process of preventive service delivery in primary care offices: a chart audit was used to measure each child's preventive service status before and after an office visit, a brief parent exit interview was used to assess preventive service delivery not documented in the chart, and a staff checklist was used to assess the role of nursing and other office staff. The feasibility of using this combination of measures to identify problems in the care delivery process was evaluated in 3 representative primary care practices (2 pediatric, 1 family practice) among children 5 years and younger.

RESULTS

The measurement method was implemented in all 3 practices. The validity of the method was supported by its ability to detect differences among practices in the proportion of children eligible for immunizations and screening tests and in the proportion of children undergoing key steps in the process of preventive service delivery. The practice with the lowest proportion of children whose charts were screened for preventive services needs had the lowest performance of preventive services.

CONCLUSIONS

It is possible to assess specific elements in the process of preventive service delivery in primary care practices. Use of this approach may help practices design and monitor interventions to improve the quality of preventive care delivery.

The rational clinical examination. Does this infant have pneumonia?

Acute lower respiratory tract illness is common among children seen in primary care. We reviewed the accuracy and precision of the clinical examination in detecting pneumonia in children. Although most cases are viral, it is important to identify bacterial pneumonia to provide appropriate therapy. Studies were identified by searching MEDLINE from 1982 to 1995, reviewing reference lists, reviewing a published compendium of studies of the clinical examination, and consulting experts. Observer agreement is good for most signs on the clinical examination. Each study was reviewed by 2 observers and graded for methodologic quality. There is better agreement about signs that can be observed (eg, use of accessory muscles, color, attentiveness; kappa, 0.48-0.66) than signs that require auscultation of the chest (eg, adventitious sounds; kappa, 0.3). Measurements of the respiratory rate are enhanced by counting for 60 seconds. The best individual finding for ruling out pneumonia is the absence of tachypnea. Chest indrawing, and other signs of increased work of breathing, increases the likelihood of pneumonia. If all clinical signs (respiratory rate, auscultation, and work of breathing) are negative, the chest x-ray findings are unlikely to be positive. Studies are needed to assess the value of clinical findings when they are used together.

Access to care: a home visitation program that links public health nurses, physicians, mothers, and babies

The purpose of the project here was to develop and test interventions designed to improve access to care and health outcomes for Medicaid-eligible infants during their first 6 months of life. The goal of the intervention was to overcome personal and structural barriers to care by combining the efforts of county health departments and private physicians' offices in 2 counties in North Carolina. The project combined home visits and an office intervention.

What mothers say about why poor children fall behind on immunizations. A summary of focus groups in North Carolina

OBJECTIVES

To develop a more thorough understanding of the factors that impede poor parents' utilization of health care services for their children and to refine interventions to improve immunization rates.

METHODS

We conducted focus group sessions with mothers whose children received care at the health departments in five North Carolina counties. Mothers were uninsured or were receiving Medicaid. A total of 50 women participated; group size varied from three to seven mothers.

RESULTS

Socially disadvantaged mothers faced barriers at multiple points in the process of obtaining preventive care for their children. Organizational barriers, such as a lack of flexibility in scheduling and long waiting times, were exacerbated by personal barriers, such as a lack of reliable transportation, chaotic home environments, and employment conflicts. Lack of knowledge regarding the timing of childhood immunizations and misperceptions about the safety of immunizations were also important obstacles. Mothers made several suggestions, such as changes in scheduling, greater assistance with transportation, improved waiting facilities, and increased health education.

CONCLUSIONS

Our study suggests that even with improved financing of well-child care, many important barriers to adequate immunization will remain. Many of the changes that mothers in our focus groups advocated are not related to insurance coverage and would be simple and inexpensive to implement. To help with these changes, we developed a checklist for use by health departments to determine which organizational barriers exist at their facility and suggest strategies to overcome the problems. Organizational, personal, and attitudinal barriers pose serious problems for socioeconomically disadvantaged families. To improve vaccination rates for children, new personnel and programs are probably less important than careful strategies to maximize existing resources.

Establishment of cell type by compartmentalized activation of a transcription factor

Early in the process of spore formation in Bacillus subtilis a septum is formed that partitions the sporangium into daughter cells called the forespore and the mother cell. The daughter cells each have their own chromosome but follow dissimilar programs of gene expression. Differential gene expression in the forespore is now shown to be established by the compartmentalized activity of the transcription factor sigma F. The sigma F factor is produced prior to septation, but is active only in the forespore compartment of the post-septation sporangium. The sigma F factor is controlled by the products of sporulation operons spoIIA and spoIIE, which may be responsible for confining its activity to one of the daughter cells.

Differentiation and the establishment of cell type during sporulation in Bacillus subtilis

Differentiation in Bacillus subtilis involves the formation of specialized cell types called the mother cell and the forespore. These differ from each other and from their parent in developmental fate. Establishment of the two cell types and their subsequent differentiation is governed by the compartmentalized action of six developmental transcription factors.

Control of developmental transcription factor sigma F by sporulation regulatory proteins SpoIIAA and SpoIIAB in Bacillus subtilis

The sporulation operon spoIIA of Bacillus subtilis consists of three cistrons called spoIIAA, spoIIAB, and spoIIAC. Little is known about the function of spoIIAA and spoIIAB, but spoIIAC encodes a sigma factor called sigma F, which is capable of directing the transcription in vitro of genes that are expressed in the forespore chamber of the developing sporangium. We now report that the products of the spoIIA operon constitute a regulatory system in which SpoIIAA is an antagonist of SpoIIAB (or otherwise counteracts the effect of SpoIIAB) and SpoIIAB is, in turn, an antagonist of SpoIIAC (sigma F). This conclusion is based on the observations that (i) overexpression of spoIIAB inhibits sigma F-directed gene expression, (ii) a mutation in spoIIAB stimulates sigma F-directed gene expression, (iii) a mutation in spoIIAA blocks sigma F-directed gene expression, and (iv) a mutation in spoIIAB relieves the block in sigma F-directed gene expression caused by a mutation in spoIIAA. The SpoIIAA/SpoIIAB/SpoIIAC regulatory system could play a role in controlling the timing of sigma F-directed gene expression and/or could be responsible for restricting sigma F-directed gene expression to the forespore chamber of the sporangium.

A psychodynamic approach to suicide prevention

This paper sets forth a new theoretical approach to understanding the psychological etiology of suicide. The theory is demonstrated by an in-depth clinical case example, and its implications for the management of the suicidal candidate in his acute interim and long-term care are described. The theory assumes that the primary motivation to suicide comes from a clinically characteristic, unremitting psychological pain. The role of the suicidal prevention center is discussed with specific emphasis on the quality of the engagement between a center staff person and the suicidal patient. A future course for suicide centers is suggested based on the theory.