New tree-ring data from Canadian boreal and hemi-boreal forests provide insight for improving the climate sensitivity of terrestrial biosphere models

Understanding boreal/hemi-boreal forest growth sensitivity to seasonal variations in temperature and water availability provides important basis for projecting the potential impacts of climate change on the productivity of these ecosystems. Our best available information currently comes from a limited number of field experiments and terrestrial biosphere model (TBM) simulations of varying predictive accuracy. Here, we assessed the sensitivity of annual boreal/hemi-boreal forest growth in Canada to yearly fluctuations in seasonal climate variables using a large tree-ring dataset and compared this to the climate sensitivity of annual net primary productivity (NPP) estimates obtained from fourteen TBMs. We found that boreal/hemi-boreal forest growth sensitivity to fluctuations in seasonal temperature and precipitation variables changed along a southwestern to northeastern gradient, with growth limited almost entirely by temperature in the northeast and west and by water availability in the southwest. We also found a lag in growth climate sensitivity, with growth largely determined by the climate during the summer prior to ring formation. Analyses of NPP sensitivity to the same climate variables produced a similar southwest to northeast gradient in growth climate sensitivity for NPP estimates from all but three TBMs. However, analyses of growth from tree-ring data and analyses of NPP from TBMs produced contrasting evidence concerning the key climate variables limiting growth. While analyses of NPP primarily indicated a positive relationship between growth and seasonal temperature, tree-ring analyses indicated negative growth relationships to temperature. Also, the positive effect of precipitation on NPP derived from most TBMs was weaker than the positive effect of precipitation on tree-ring based growth: temperature had a more important limiting effect on NPP than tree-ring data indicated. These mismatches regarding the key climate variables limiting growth suggested that characterization of tree growth in TBMs might need revision, particularly regarding the effects of stomatal conductance and carbohydrate reserve dynamics.

Adding Tree Rings to North America's National Forest Inventories: An Essential Tool to Guide Drawdown of Atmospheric CO2

Tree-ring time series provide long-term, annually resolved information on the growth of trees. When sampled in a systematic context, tree-ring data can be scaled to estimate the forest carbon capture and storage of landscapes, biomes, and—ultimately—the globe. A systematic effort to sample tree rings in national forest inventories would yield unprecedented temporal and spatial resolution of forest carbon dynamics and help resolve key scientific uncertainties, which we highlight in terms of evidence for forest greening (enhanced growth) versus browning (reduced growth, increased mortality). We describe jump-starting a tree-ring collection across the continent of North America, given the commitments of Canada, the United States, and Mexico to visit forest inventory plots, along with existing legacy collections. Failing to do so would be a missed opportunity to help chart an evidence-based path toward meeting national commitments to reduce net greenhouse gas emissions, urgently needed for climate stabilization and repair.

Do Women With Anxiety or Depression Have Higher Rates of Myocardial Ischemia During Exercise Testing Than Men?

BACKGROUND

Women diagnosed with coronary artery disease (CAD) typically experience worse outcomes relative to men, possibly through diagnosis and treatment delays. Reasons for these delays may be influenced by mood and anxiety disorders, which are more prevalent in women and have symptoms (eg, palpitations and fatigue) that may be confounded with CAD. Our study examined sex differences in the association between mood and anxiety disorders and myocardial ischemia in patients with and without a CAD history presenting for exercise stress tests.

METHODS AND RESULTS

A total of 2342 patients (women n=760) completed a single photon emission computed tomographic exercise stress test (standard Bruce Protocol) and underwent a psychiatric interview (The Primary Care Evaluation of Mental Disorders) to assess mood and anxiety disorders. Ischemia was assessed using single photon emission computed tomography, with odds ratio used to calculate the effect of sex and mood/anxiety on the presence of ischemia during stress testing by CAD history in a stratified analyses, adjusted for relevant covariates. There was a sex by anxiety interaction with ischemia in those without a CAD history (P=0.015): women with anxiety were more likely to exhibit ischemia during exercise than women without anxiety (odds ratio, 1.75; 95% confidence interval, 1.05-2.89). No significant effects were observed for men nor mood.

CONCLUSIONS

Women with anxiety and no CAD history had higher rates of ischemia than women without anxiety. Results suggest that anxiety symptoms, many of which overlap with those of CAD, might mask CAD symptoms among women (but not men) and contribute to referral and diagnostic delays. Further research is needed to confirm this hypothesis.

Exercise Lowers Plasma Angiopoietin-Like 2 in Men with Post-Acute Coronary Syndrome

Pro-inflammatory angiopoietin-like 2 (angptl2) promotes endothelial dysfunction in mice and circulating angptl2 is higher in patients with cardiovascular diseases. We previously reported that a single bout of physical exercise was able to reduce angptl2 levels in coronary patients. We hypothesized that chronic exercise would reduce angptl2 in patients with post-acute coronary syndrome (ACS) and endothelial dysfunction. Post-ACS patients (n = 40, 10 women) were enrolled in a 3-month exercise-based prevention program. Plasma angptl2, hs-CRP, and endothelial function assessed by scintigraphic forearm blood flow, were measured before and at the end of the study. Exercise increased VO₂peak by 10% (p<0.05), but did not significantly affect endothelial function, in both men and women. In contrast, exercise reduced angptl2 levels only in men (-26±7%, p<0.05), but unexpectedly not in women (+30±16%), despite similar initial levels in both groups. Exercise reduced hs-CRP levels in men but not in women. In men, levels of angptl2, but not of hs-CRP, reached at the end of the training program were negatively correlated with VO₂peak (r = -0.462, p = 0.012) and with endothelial function (r = -0.419, p = 0.033) measured at baseline: better initial cardiopulmonary fitness and endothelial function correlated with lower angptl2 levels after exercise. Pre-exercise angptl2 levels were lower if left ventricular ejection time was long (p<0.05) and the drop in angptl2 induced by exercise was greater if the cardiac output was high (p<0.05). In conclusion, in post-ACS men, angptl2 levels are sensitive to chronic exercise training. Low circulating angptl2 reached after training may reflect good endothelial and cardiopulmonary functions.

Relative associations between depression and anxiety on adverse cardiovascular events: does a history of coronary artery disease matter? A prospective observational study

OBJECTIVES

To assess whether depression and anxiety increase the risk of mortality and major adverse cardiovascular events (MACE), among patients with and without coronary artery disease (CAD).

DESIGN AND SETTING, AND PATIENTS

DECADE (Depression Effects on Coronary Artery Disease Events) is a prospective observational study of 2390 patients referred at the Montreal Heart Institute. Patients were followed for 8.8 years, between 1998 and 2009. Depression and anxiety were assessed using a psychiatric interview (Primary Care Evaluation of Mental Disorders, PRIME-MD). Outcomes data were obtained from Quebec provincial databases.

MAIN OUTCOME MEASURES

All-cause mortality and MACE.

RESULTS

After adjustment for covariates, patients with depression were at increased risks of all-cause mortality (relative risk (RR)=2.84; 95% CI 1.25 to 6.49) compared with patients without depression. Anxiety was not associated with increased mortality risks (RR=0.86; 95% CI 0.31 to 2.36). When patients were stratified according to CAD status, depression increased the risk of mortality among patients with no CAD (RR=4.39; 95% CI 1.12 to 17.21), but not among patients with CAD (RR=2.32; 95% CI 0.78 to 6.88). Neither depression nor anxiety was associated with MACE among patients with or without CAD.

CONCLUSIONS AND RELEVANCE

Depression, but not anxiety, was an independent risk factor for all-cause mortality in patients without CAD. The present study contributes to a better understanding of the relative and unique role of depression versus anxiety among patients with versus without CAD.

Differential association of insulin resistance with cognitive and somatic symptoms of depression

AIM

To examine the associations of depressive symptoms with insulin resistance, evaluating somatic and cognitive depressive symptoms separately.

METHODS

A total of 328 individuals (mean age 60 years) referred for exercise stress testing, taking part in the Mechanisms and Outcomes of Silent Myocardial Ischemia study, completed the Beck Depression Inventory II. A fasting venous blood sample was collected for assessments of insulin and glucose level; the HOMA-IR (homeostatic model assessment of insulin resistance) was calculated. In principal component analysis, Beck Depression Inventory II items were forced to load onto two components (somatic and cognitive depressive symptoms). Adjusting for age, sex, BMI, medication use, smoking, physical activity, diabetes and cardiovascular disease, general linear model analyses were conducted to examine the associations between the components and log HOMA-IR .

RESULTS

Principal component analysis showed that nine items loaded onto a cognitive depressive symptoms component and 10 items loaded onto a somatic depressive symptoms component. When examined separately, both components were significantly associated with log HOMA-IR however, when including both components simultaneously in the model, only somatic depressive symptoms remained significantly associated with log HOMA-IR. Back-transformed, a one-unit change in somatic depressive symptoms was associated with a 1.07 (95% CI 1.002, 1.14) change in HOMA-IR and a one-unit change in cognitive depressive symptoms was associated with a 1.03 (95% CI 0.97, 1.14) change in HOMA-IR.

CONCLUSION

Somatic depressive symptoms seem to be more strongly associated with insulin resistance than do cognitive depressive symptoms. Monitoring somatic depressive symptoms may be more appropriate than monitoring cognitive depressive symptoms among depressed individuals with high insulin resistance.

The interaction between anxiety and depressive symptoms on brachial artery reactivity in cardiac patients

The association between anxiety, depression, and endothelial function (EF) was assessed in a sample of 295 cardiac outpatients (n=222 men; mean age=59). Patients were administered the Beck Depression Inventory-II and the State-Trait Anxiety Inventory, trait scale. EF was assessed through forearm hyperemic reactivity, a nuclear medicine variation of the flow-mediated dilatation technique, which calculates the rate of uptake ratio (RUR) between hyperaemic and non-hyperaemic arms. Neither effect of anxiety (F=1.40, p=.24) nor depression (F=2.66, p=.10) was found in a model predicting EF, however there was an interaction (F=4.11, p=.04). Higher anxiety and lower depressive symptoms were associated with superior RUR compared to lower anxiety and lower depressive symptoms. Anxiety had no influence on RUR in those patients with higher depressive symptoms, who generally displayed the lowest levels of RUR, i.e., poor function. It is speculative whether this potential protective role of anxiety may be guided by behavioral or physiological mechanisms.

Examining historical and current mixed-severity fire regimes in ponderosa pine and mixed-conifer forests of western North America

There is widespread concern that fire exclusion has led to an unprecedented threat of uncharacteristically severe fires in ponderosa pine (Pinus ponderosa Dougl. ex. Laws) and mixed-conifer forests of western North America. These extensive montane forests are considered to be adapted to a low/moderate-severity fire regime that maintained stands of relatively old trees. However, there is increasing recognition from landscape-scale assessments that, prior to any significant effects of fire exclusion, fires and forest structure were more variable in these forests. Biota in these forests are also dependent on the resources made available by higher-severity fire. A better understanding of historical fire regimes in the ponderosa pine and mixed-conifer forests of western North America is therefore needed to define reference conditions and help maintain characteristic ecological diversity of these systems. We compiled landscape-scale evidence of historical fire severity patterns in the ponderosa pine and mixed-conifer forests from published literature sources and stand ages available from the Forest Inventory and Analysis program in the USA. The consensus from this evidence is that the traditional reference conditions of low-severity fire regimes are inaccurate for most forests of western North America. Instead, most forests appear to have been characterized by mixed-severity fire that included ecologically significant amounts of weather-driven, high-severity fire. Diverse forests in different stages of succession, with a high proportion in relatively young stages, occurred prior to fire exclusion. Over the past century, successional diversity created by fire decreased. Our findings suggest that ecological management goals that incorporate successional diversity created by fire may support characteristic biodiversity, whereas current attempts to "restore" forests to open, low-severity fire conditions may not align with historical reference conditions in most ponderosa pine and mixed-conifer forests of western North America.

The impact of metabolic syndrome and endothelial dysfunction on exercise-induced cardiovascular changes

OBJECTIVE

There is limited information regarding the synergistic or additive effects of metabolic syndrome (MS) and endothelial dysfunction (ED) on cardiovascular disease (CVD). Altered cardiovascular responses to exercise have been shown to predict future cardiovascular events as well as assess autonomic function. The present study evaluated the impact of MS and brachial artery reactivity (a proxy of ED) on peak exercise-induced cardiovascular changes.

DESIGN AND METHODS

Individuals (n = 303) undergoing a standard nuclear medicine exercise stress test were assessed for MS. Participants underwent a Forearm Hyperaemic Reactivity test and were considered to have dysfunctional reactivity if their rate of uptake ratio (RUR) was <3.55. Resting and peak blood pressure (BP) and heart rate (HR) were measured. Reactivity was calculated as the difference between peak and resting measures.

RESULTS

Analyses, adjusting for age, sex, resting HR, total metabolic equivalents (METs), and a history of major CVD, revealed a main effect of MS (F = 5.51, η(2) = 0.02, P = 0.02) and RUR (F = 6.69, η(2) = 0.02, P = 0.01) on HR reactivity, such that patients with MS and/or poor RUR had reduced HR reactivity. There were no interactive effects of RUR and MS. There were no effects of RUR or MS on systolic BP (SBP) or diastolic BP (DBP) reactivity or rate pressure product (RPP) reactivity.

CONCLUSIONS

The presence of decreased HR reactivity among participants with MS or poor brachial artery reactivity, combined with the lack of difference in other exercise-induced cardiovascular changes, indicates that these patients may have some degree of parasympathetic dysregulation. Further longitudinal studies are needed to understand the long-term implications of MS and endothelial abnormalities in this context.

The research on endothelial function in women and men at risk for cardiovascular disease (REWARD) study: methodology

Background

Endothelial function has been shown to be a highly sensitive marker for the overall cardiovascular risk of an individual. Furthermore, there is evidence of important sex differences in endothelial function that may underlie the differential presentation of cardiovascular disease (CVD) in women relative to men. As such, measuring endothelial function may have sex-specific prognostic value for the prediction of CVD events, thus improving risk stratification for the overall prediction of CVD in both men and women. The primary objective of this study is to assess the clinical utility of the forearm hyperaemic reactivity (FHR) test (a proxy measure of endothelial function) for the prediction of CVD events in men vs. women using a novel, noninvasive nuclear medicine -based approach. It is hypothesised that: 1) endothelial dysfunction will be a significant predictor of 5-year CVD events independent of baseline stress test results, clinical, demographic, and psychological variables in both men and women; and 2) endothelial dysfunction will be a better predictor of 5-year CVD events in women compared to men.

Methods/Design

A total of 1972 patients (812 men and 1160 women) undergoing a dipyridamole stress testing were recruited. Medical history, CVD risk factors, health behaviours, psychological status, and gender identity were assessed via structured interview or self-report questionnaires at baseline. In addition, FHR was assessed, as well as levels of sex hormones via blood draw. Patients will be followed for 5 years to assess major CVD events (cardiac mortality, non-fatal MI, revascularization procedures, and cerebrovascular events).

Discussion

This is the first study to determine the extent and nature of any sex differences in the ability of endothelial function to predict CVD events. We believe the results of this study will provide data that will better inform the choice of diagnostic tests in men and women and bring the quality of risk stratification in women on par with that of men.

Silent ischemia: silent after all?

OBJECTIVE

To examine the association of nonpain symptoms in men and women with exercise-related silent ischemia, as well as the independence of these findings from other clinical factors.

METHODS

A prospective study of 482 women and 425 men (mean age 58 years) undergoing exercise stress testing with myocardial perfusion imaging. Analyses were performed on 60 women and 155 men with no angina but medical perfusion imaging evidence of ischemia during exercise.

MEASURES

The presence of various non-pain-related symptoms. Ischemia is indicated by myocardial perfusion defects on exercise stress testing with single photon emission computed tomography.

RESULTS

Women reported more nonangina symptoms than men (P<0.05). They experienced fatigue, hot flushes, tense muscles, shortness of breath and headaches more frequently (P<0.05). Symptoms relating to muscle tension and diaphoresis were associated with ischemia after controlling for pertinent clinical covariates. However, the direction of association differed according to sex and history of coronary artery disease events or procedures. Sensitivity of the detection models showed modest improvements with the addition of these symptoms.

CONCLUSIONS

While patients who experience silent ischemia experience a number of nonpain symptoms, those symptoms may not be sufficiently specific to ischemia, nor sensitive in detecting ischemia, to be of particular help to physicians in the absence of other clinical information.

Health behaviors and endothelial function

An unhealthy lifestyle, including excess caloric intake, lack of exercise, smoking, and excessive alcohol consumption, increases one's risk of developing cardiovascular disease (CVD). However, the exact mechanisms by which these behaviors influence the development and progression of CVD have yet to be determined. Endothelial function (EF) has been shown to be a potent predictor of CVD, yet the effects of health behaviors on EF are not clear. The literature assessing the role of four health behaviors, obesity (a proxy of excess caloric intake), smoking, physical inactivity, and alcohol consumption, on the development of endothelial dysfunction is reviewed. Potential mechanisms through which these behaviors may influence EF are discussed. Smoking, being overweight or obese, and physical inactivity are all associated with decreased EF. A direct causal relationship between these measures and EF is suggested by the fact that improvements in these behaviors leads to parallel improvements in EF. The influence of alcohol consumption is somewhat more contentious, with some studies indicating a dose-response relationship such that those with greater consumption have poor EF. However, other studies have shown that those who drink moderately have the best EF. Although there is a growing body of literature implicating poor health behaviors in the development of endothelial dysfunction, more work is needed to establish the exact mechanisms by which this occurs. To our knowledge, there are no studies that have assessed the impact of multiple health behaviors or the interaction of health behaviors on EF.

Soil seed banks and plant community assembly following disturbance by fire and logging in interior Douglas-fir forests of south-central British Columbia

Relationships between soil seed banks and aboveground understory vegetation were examined in dry Douglas-fir (Pseudotsuga menziesii (Beissn.) Franco) forests near Kamloops, British Columbia, to compare the effects of different disturbance types (low and high severity fires and non-salvage logging), and to evaluate how seed banks contribute to post-disturbance vegetation establishment. Sites were selected to represent disturbances at 1, 5, and 10 years prior to sampling, and data were analyzed using nonparametric univariate and multivariate statistical techniques. Seed density and species composition of seed banks did not differ significantly among the 1 year disturbed sites; however, the rooted frequencies of seed-origin plants in the establishing vegetation decreased in the order: lightly burned > severely burned > logged. Seed dispersal within the first year following fire is believed to be an important recovery mechanism on burned sites. Low frequencies of seed-derived plants, particularly conifer seedlings, on logged sites pose concerns for the initial recovery of vegetation following logging; nonetheless, the lack of significant differences in understory species composition between sites burned 5 years prior to sampling and sites logged 10 years prior to sampling, and their corresponding undisturbed sites, suggests that vegetation recovery can occur relatively quickly. Rooted frequencies of plants establishing naturally in burned areas were similar to those in undisturbed areas, which suggests that post-fire erosion control seeding using agronomic species may not be necessary in these forests.

Detection of exercise-induced myocardial ischemia from symptomatology experienced during testing in men and women

BACKGROUND AND OBJECTIVES

To examine the capacity of angina and related symptoms experienced during exercise-stress testing to detect the presence of ischemia, controlling for other clinical factors.

METHOD

The authors undertook a prospective study of 482 women and 425 men (mean age 58 years) undergoing exercise stress testing with myocardial perfusion imaging. One hundred forty-six women and 127 men reported chest pain, and of these, 25% of women and 66% of men had myocardial perfusion imaging evidence of ischemia during testing. The present article focuses on patients with chest pain during testing.

MAIN OUTCOME MEASURES

Outcome measures included chest pain localization, extension, intensity and quality, as well as the presence of various nonpain-related symptoms. Backward logistical regression analyses were performed separately on men and women who had experienced chest pain during testing.

RESULTS

Men who described their chest pain as 'heavy' were 4.6 times more likely to experience ischemia during testing (P=0.039) compared with other men, but this pain descriptor only slightly improved accuracy of prediction beyond that provided by control variables. In women, several symptoms added to the sensitivity of the prediction, such as a numb feeling in the face or neck region (OR 4.5; P=0.048), a numb feeling in the chest area (OR 14.6; P=0.003), muscle tension (OR 5.2; P=0.013), and chest pain that was described as hot or burning (OR 4.3; P=0.014).

CONCLUSIONS

A more refined evaluation of symptoms experienced during testing was particularly helpful in improving detection of ischemia in women, but not in men. Attention to these symptoms may favour timely diagnosis of myocardial perfusion defects in women.

The role of ischaemia and pain in the blood pressure response to exercise stress testing in patients with coronary heart disease

Silent myocardial ischaemia is a common phenomenon in patients with coronary heart disease. However, very little is known about the underlying mechanisms of silent ischaemia. One potential pathway that may contribute to this absence of pain is increased blood pressure. The main aim of the current study was to assess the associations among blood pressure, pain and ischaemia in patients undergoing a standard exercise stress test. We hypothesized that patients who experienced chest pain during exercise would have lower baseline and peak blood pressures compared to those who did not experience chest pain. A total of 1,355 patients (418 women) who underwent a single-photon emission computed tomography treadmill exercise stress test and had not experienced a cardiac event in the past 2 weeks participated in the current study. Myocardial perfusion defects were assessed at rest and during the stress challenge. Systolic blood pressure (SBP), diastolic blood pressure, heart rate (HR) and rate pressure product (RPP) were assessed during rest and at peak exercise. There were no main effects of either pain or ischaemia on the baseline cardiovascular variables. Peak exercise data revealed main effects of pain on SBP, RPP and HR, and main effects of ischaemia on SBP and RPP, controlling for age, sex, baseline level, medication status and cardiac history. These findings suggest that acute rather than chronic increases in blood pressure may be one mechanism to explain the phenomena of silent myocardial ischaemia in cardiac patients, and may potentially provide a target for future treatment strategies.

Angina symptoms in men and women with stable coronary artery disease and evidence of exercise-induced myocardial perfusion defects

BACKGROUND

To examine sex differences in pain and associated symptoms in patients with exercise-related ischemia, as well as the independence of these findings from other clinical factors.

METHODS

Prospective study of 482 women and 425 men (mean age 58 years) undergoing exercise stress testing with myocardial perfusion imaging (MPI). Analyses were performed on 38 women and 94 men with both angina and MPI evidence of ischemia during exercise.

MEASURES

Chest pain localization, extension, intensity, quality, and presence of various non-pain-related symptoms.

RESULTS

Women rated their pain as more intense, used different words to describe it, and reported more non-pain-related symptoms than men (P < .05). They experienced pain and other sensations in the neck area more frequently (P < .05). Most of these differences remained after controlling for clinical or psychological variables, with the exception of pain intensity measures.

CONCLUSIONS

Sex differences in the experience of symptoms associated with MPI evidence of myocardial ischemia may complicate timely and accurate diagnosis of ischemia in women.

A pilot study: the Noninvasive Surface Cooling Thermoregulatory System for Mild Hypothermia Induction in Acute Myocardial Infarction (the NICAMI Study)

BACKGROUND

Hypothermia reduces metabolic demands, limits reperfusion injury, and helps salvage the injured myocardium during ST-elevation myocardial infarction (STEMI). The aim of this study was to assess early induction of noninvasive mild hypothermia in patients with acute myocardial infarction undergoing primary percutaneous coronary intervention (PCI).

METHODS

This was a safety and feasibility study of the Medivance Arctic Sun noninvasive thermoregulatory system (Medivance Inc, Louisville, Colo), used as adjunctive therapy in patients with first-time STEMI. Cooling was initiated by circulating chilled water through the Arctic Sun Energy Transfer Pads placed on the patient before primary PCI. Target temperature was 34.5 degrees C, maintained during 3 hours. Shivering was controlled with intravenous meperidine, and meperidine-related nausea was prevented with intravenous ondansetron.

RESULTS

Nine patients underwent successful noninvasive surface cooling. All patients were Killip class I with a mean age of 62 years (8/9 males). Successful primary stenting was performed in all patients with glycoprotein inhibitors administered in 6 of 9 cases. Mean cooling time from induction to target temperature was 79 minutes (49 minutes in the last 4 enrolled cases). Mean total cooling duration was 267 minutes. Mean peak troponin T was 5.81 microg/L. Final TIMI flow grade 3 and final TIMI perfusion grade 3 were achieved in 9 of 9 patients and in 3 of 9 patients, respectively. Mean infarct size (by Myoview single photon emission computed tomography scans) was 23%. No hemodynamic or arrhythmic instability were documented.

CONCLUSION

Mild hypothermia can be safely induced with noninvasive surface cooling in patients with STEMI undergoing primary PCI, allowing earlier myocardial protection before mechanical reperfusion therapy.

Myocardial perfusion study of panic attacks in patients with coronary artery disease

Panic disorder (PD) and panic-like anxiety have been associated with an increased risk of cardiovascular death. No study has specifically examined the association between panic attacks and ischemia in patients who have coronary artery disease (CAD). We hypothesized that panic attacks would induce myocardial perfusion defects in patients who have CAD and PD. Sixty-five patients who had CAD and positive results with nuclear exercise stress testing (35 with PD and 30 without PD served as controls) underwent a well-established panic challenge test (1 vital capacity inhalation of a gas mixture containing 35% carbon dioxide and 65% oxygen) and were injected with technetium-99m sestamibi at inhalation. Single-photon emission computed tomography was used to assess per-panic challenge perfusion defects, and heart rate, blood pressure, and 12-lead electrocardiogram were continuously measured during the procedure. Patients were not withdrawn from their cardiac medications. Patients who had PD were significantly younger than the controls; otherwise groups did not differ with respect to gender, cardiac medications, nuclear exercise test results, and baseline heart rate and blood pressure. Seventy-four percent of patients (26 of 35) who had PD had a panic attack at inhalation versus 6.7% of controls (2 of 30, p <0.001). As hypothesized, patients who had PD and demonstrated a panic attack were more likely to develop a reversible myocardial perfusion defect than were controls who did not have an attack (80.9% vs 46.4% p = 0.009). Thus, despite being on their cardiac medications, panic attacks preferentially induced significant perfusion defects in patients who had CAD and PD. In conclusion, panic attacks in patients who have CAD appear to be bad for the heart.

Rémunération, postes de travail et accidents: Une relation interactive

La principale conclusion de cet article est qu'il existe un lien significatif entre le mode de rémunération et le risque d'accidents qui est interactif avec le poste de travail, la remuneration au rendement s'accompagnant d'un risque réduit chez les ébénistes et menuisiers et accru chez les manœuvres. De plus, chez ces derniers, le risque d'accidents est significativement plus élevé pour certains sièges spécifiques de lésion: la colonne lombaire, les poignets et les doigts.

Absentéisme et assiduité au travail: deux moyens d'adaptation au stress

Les objectifs de cette étude sont de tester de nouveau les relations entre d'une part le stress intrinsèque et extrinsèque et d'autre part, l'absence et l'assiduité au travail et de déterminer la nature des relations entre le stress au travail et différentes mesures de fréquence des absences et de temps perdu.

Personality, Social Support and Workers' Stress

The study examines social support as a correlate of perceived job demands and psychological strain and as a moderator of the relationship between stimulus and response, according to personality traits. 807 hospital employees were administered an occupational stress questionnaire. Data was obtained regarding two sources of job demands (intrinsic and extrinsic), three psychological symptoms (anxiety, depression and irritation), four categories of personality and three areas of social support. Using hierarchical regression procedures (Arnold 1982) the results suggest that the effects of social support vary significantly depending upon the source of job demands, the workers' personality and the psychological symptom manifested.

Quantitative hyperemic reactivity in opposed limbs during myocardial perfusion imaging: a new marker of coronary artery disease

OBJECTIVES

We sought to evaluate the feasibility and validity of a new method to quantify the hyperemic response of the forearms that can be incorporated into a rest myocardial perfusion protocol.

BACKGROUND

Evaluation of the hyperemic response could provide useful clinical information in the detection and risk stratification of atherosclerotic vascular disease.

METHODS

Patients with proven coronary artery disease (CAD) (n = 46) were compared with low-risk subjects without such evidence (n = 47). A regular dose of Myoview was injected after 5 min of right arm ischemia. Three dimensionless parametric ratios (right/left) were derived from the analysis of activity-time curves of the hyperemic right forearm and that of the contralateral left forearm.

RESULTS

The maximal ingress upslope ratio was 40% lower in the CAD group (3.0 +/- 0.2 vs. 4.2 +/- 0.3, p < 0.0005), and the integral to peak ratio was also lower (23 +/- 4 vs. 52 +/- 11, p < 0.01), whereas the peak activity ratio was nonsignificantly lower (3.0 +/- 0.3 vs. 3.8 +/- 0.3, p = 0.07). Using a value of 3.55 for the maximal upslope ratio, this approach could predict the presence of CAD with a sensitivity of 0.70 and a specificity of 0.60.

CONCLUSIONS

This simple and noninvasive method is feasible and can discriminate between patients with known CAD and those at low risk of atherosclerosis. Refinements of this approach and its inclusion in larger clinical trials are needed to determine whether it could provide additional value to myocardial scintigraphic imaging.

Are exercise stress tests appropriate for assessing myocardial ischemia in patients with major depressive disorder?

BACKGROUND

Major depressive disorder (MDD) disproportionately affects patients with coronary artery disease (CAD). Evidence of myocardial ischemia with electrocardiography (ECG) or single-photon-emission-computed-tomography (SPECT) assessments during exercise testing is an important determinant of CAD prognosis. However, many key symptoms of MDD, such as reduced interest in daily activities, lack of energy, and fatigue, may affect exercise performance and the detection of ischemia in patients with MDD. This study evaluated the extent to which MDD and depressive symptomatology moderate exercise test performance and compared the ability of ECG versus SPECT for detecting ischemia in 1367 consecutive patients who underwent exercise testing.

METHODS

All patients underwent a brief, structured psychiatric interview (PRIME-MD) and completed the Beck Depression Inventory (BDI) on the day of their exercise (treadmill) test.

RESULTS

A total of 183 patients (13%) met diagnostic criteria for MDD. Patients with MDD achieved a significantly lower percent of maximal predicted heart rate (%MPHR), exhibited lower peak exercise mets, and spent less time exercising compared with patients without MDD (all P values <.05). BDI scores were also negatively correlated with all 3 indices of exercise performance (all P values <.01). There were no differences in rates of SPECT ischemia in patients with MDD (40%) versus patients without MDD (45%; P =.23); however, rates of ECG ischemia were significantly lower (30%) in patients with MDD than in patients without MDD (48%; P <.0001).

CONCLUSIONS

Results suggest that patients with CAD who have MDD, depressive symptomatology, or both exhibit poor exercise tolerance and performance and that ECG, as compared with SPECT, may not be as reliable in detecting ischemia in patients who are depressed.

β-Radiation for the Creation of Linear Lesions in the Canine Atrium

Background— Creating linear lesions is important for the treatment of arrhythmias such as atrial flutter and fibrillation. Making these lesions with standard radiofrequency catheters can be difficult and may result in charring and thrombosis. The purpose of this study was to evaluate β-radiation as a novel energy source for creating linear myocardial lesions.

Methods and Results— Eight dogs with intact conduction across the cavotricuspid isthmus were studied. The isthmus was irradiated (25 to 50 Gy) with strontium/yttrium-90 delivered via a deflectable 7F catheter (Novoste Corporation). There were no immediate effects, but bidirectional conduction block developed during follow-up studies in 7 of 8 dogs. The dog without conduction block received 25 Gy. After the animals were euthanized, histology revealed transmural, linear areas of fibrosis without any thrombus.

Conclusions— β-Radiation can safely and effectively create linear lesions that are contiguous and nonthrombogenic. This energy source may become an interesting adjunct to radiofrequency for the treatment of atrial flutter and fibrillation.

Shell cross-linked cylinders of polyisoprene-b-ferrocenyldimethylsilane: formation of magnetic ceramic replicas and microfluidic channel alignment and patterning

Stable organometallic cylindrical nanostructures have been prepared by shell cross-linking of PI320-b-PFS53 wormlike micelles in hexane through metal-catalyzed hydrosilylation at 23 degrees C. The cross-linked structures permit the formation of cylindrical ceramic replicas containing size- and separation-tunable arrays of Fe nanoclusters. In addition, microfluidic alignment of the cross-linked cylinders was possible.

Detection of myocardial perfusion abnormalities after a recent acute coronary syndrome by quantitative Levovist myocardial contrast echocardiography: comparison with 99m Tc-Myoview SPECT imaging

BACKGROUND

The value of stress harmonic power Doppler imaging (HPDI) for the evaluation of myocardial perfusion has never been assessed in patients after acute coronary syndrome (ACS).

OBJECTIVE

To evaluate the agreement between stress HPDI and single photon emission computed tomography (SPECT) imaging for the assessment of myocardial perfusion after unstable angina or myocardial infarction.

PATIENTS AND METHODS

Thirty patients with a recent ACS underwent HPDI and SPECT. Images were obtained at rest and during dipyridamole infusion (0.56 mg/kg over 4 min). Apical two- and four-chamber views were used for HPDI. Ten myocardial segments were scored for myocardial perfusion. Semiquantitative and quantitative video intensity analysis with background subtraction were performed.

RESULTS

Concordance by patients between quantitative HPDI and SPECT was 76% (kappa=0.40, Phi=0.46) for normal versus abnormal perfusion. When semiquantitative analysis was used, concordance was 72% (kappa=0.42, Phi=0.46). Agreement between methods was best in the left anterior descending artery territory for quantitative (80%) (kappa=0.60, Phi=0.60) and semiquantitative analysis (78%) (kappa=0.51, Phi=0.60) for normal versus abnormal perfusion. Discrepancies between HPDI and SPECT were most important in the circumflex territory, with a concordance of 59% (kappa=0.22) for identification of normal perfusion versus irreversible and reversible defects.

CONCLUSIONS

These results suggest that HPDI can detect myocardial perfusion at rest and during pharmacological stress in patients after a recent ACS. Given the suboptimal agreement with SPECT, further advances are required before the routine use of contrast echocardiography is possible for the assessment of myocardial perfusion.

Two-year angiographic follow-up of intracoronary Sr90 therapy for restenosis prevention after balloon angioplasty

BACKGROUND

Postcoronary angioplasty vascular brachytherapy (VBT) has emerged as a successful intervention for restenosis prevention in some clinical scenarios. Longer-term follow-up after VBT in de novo nonstented lesions has not been reported.

METHODS AND RESULTS

Thirty patients treated with post-percutaneous transluminal coronary angioplasty (PTCA) VBT with Sr90 underwent clinical and angiographic follow-up at 6 and 24 months. Specific vessel segment quantitative coronary angiographic analyses were performed to identify radiation edge effects. Nineteen patients who had not undergone index procedure stenting or target vessel revascularization (TVR) over the 2-year period were analyzed separately. Of the 30 patients, 3 underwent TVR by 6-month follow-up. An additional 4 patients required TVR between 6 and 24 months. In the total cohort of 26 patients undergoing angiographic follow-up at 6 and 24 months, an increase in minimal lumen diameter of the initial target segment was noted at 6 months compared with postprocedure analysis (2.31+/-0.48 versus 2.04+/-0.43 mm, P<0.05). At 24 months, this was no longer significant (2.19+/-0.61 mm). In the proximal segments of the entire cohort and the nonintervened subgroup, the principal late loss occurred over the first 6 months with no additional late loss at 2-year follow-up. The distal segments remained stable over the entire follow-up period.

CONCLUSIONS

Although some late failures of post-PTCA VBT are seen between 6 and 24 months, most treated vessels remain stable with no late loss or additional luminal increase beyond the 6-month period. This suggests that late aneurysm formation and significant late edge restenosis are unlikely in VBT after PTCA of de novo lesions for up to 2 years.

Treatment of long, diffuse, in-stent restenotic lesions with beta radiation using strontium 90 and sequential positioning "pullback" technique: procedural details and clinical outcomes

BACKGROUND

Long, diffuse, in-stent restenotic lesions have been problematic for many patients, necessitating the need for multiple repeat percutaneous coronary interventions (PCI). The need for repeat PCI has been significantly reduced in patients since the advent of vascular brachytherapy. In-stent restenosis resulting in long lesions (> 30 mm) presents even more of a challenge. The interventional injury length created during PCI is usually greater than 30 mm and the vascular brachytherapy systems available in most hospitals are 30 mm or 40 mm in length. The purpose of this paper is to define "pullback technique" and to report the Montreal Heart Institute (MHI) data to show that the pullback technique using the Novoste system seems to be a safe and effective method for using vascular brachytherapy to treat long, diffuse, in-stent restenotic lesions.

METHODS

We reviewed the database of patients enrolled in the Compassionate Use Registry between August 1999 and July 2000. The data are reported on 23 consecutive patients treated with the pullback technique.

RESULTS

The mean lesion length was 49.4 +/- 19.8 mm. Three patients (13%) underwent target vessel revascularization. Angiographic follow-up was obtained in 18 patients (78%). Seven patients (38.8%) showed angiographic restenosis (> 50% luminal re-narrowing). No aneurysms or zones of ectasia were noted.

CONCLUSION

This angiographic and clinical evaluation of the MHI Compassionate Use Registry data show the pullback technique to be safe from both a dosimetric and clinical point of view.

Sauna-induced myocardial ischemia in patients with coronary artery disease

PURPOSE

Sauna bathing is a popular recreational activity that is generally considered to be safe. However, there have been case reports of adverse cardiac events. We sought to determine whether sauna use caused myocardial ischemia in patients with coronary artery disease.

METHODS

Sixteen patients with proven coronary artery disease were submitted to three conditions (rest, exercise, and sauna bathing) with continuous electrocardiographic (ECG) monitoring and regular blood pressure measurements. During each condition, patients were injected with Tc-99 sestamibi followed by nuclear scintigraphic imaging. Perfusion defect scores were calculated in 15 patients.

RESULTS

Sauna bathing was well tolerated. There was a mean (+/- SD) increase in heart rate of 32% +/- 20% in the sauna (resting mean heart rate = 60 +/- 9 beats per minute vs sauna mean heart rate = 79 +/- 11 beats per minute, P <0.001) and a 13% +/- 6% drop in systolic blood pressure (resting mean systolic blood pressure = 142 +/- 14 mm Hg vs sauna mean systolic blood pressure = 123 +/- 15 mm Hg, P <0.001). There were no arrhythmias or ECG changes in the sauna. Compared with rest, there was significant ischemia during sauna bathing (average perfusion defect score at rest = -0.44 vs average sauna score = -0.93, P <0.001). The perfusion defect score in the sauna was worse than the resting score in 14 of the 15 patients. Sauna-associated perfusion defect scores were highly correlated with exercise-induced scores (R2 = 0.65, P <0.001).

CONCLUSION

In patients with stable coronary artery disease, sauna use is clinically well tolerated but is associated with scintigraphically demonstrated myocardial ischemia.

Effects of intracoronary beta-radiation therapy after coronary angioplasty: an intravascular ultrasound study

BACKGROUND

Endovascular radiation is emerging as a potential solution for the prevention and treatment of restenosis. Its effects on the morphology of unstented vessels cannot be determined by angiography and therefore require the use of intravascular ultrasound.

METHODS AND RESULTS

Through a 5F noncentered catheter for delivery of a 90Sr/Y source train, 12, 14, or 16 Gy at 2 mm was delivered to native coronary arteries after successful balloon angioplasty in 30 patients. Four patients required stent deployment in the first week. Quantitative coronary angiography and IVUS were performed during the initial procedure and at 6-month follow-up. Binary angiographic restenosis was present in 3 of 30 patients, with target lesion and vessel revascularization performed in 3 and 5 patients, respectively. Angiographic late loss was -0.02+/-0.60 mm, with a -0.09+/-0.46 loss index. IVUS demonstrated no significant reduction in lumen area (from 5.69+/-1.72 mm2 after treatment to 6. 04+/-2.63 mm2 at follow-up), with no significant change in external elastic membrane area (13.71+/-4.54 to 14.22+/-4.71 mm2) over the 6-month follow-up. Wall area was 8.01+/-3.85 mm2 after radiation therapy and 8.19+/-3.44 mm2 at follow-up (P=NS). No significant differences were noted between the different dose groups.

CONCLUSIONS

beta-Radiation therapy resulted in a low restenosis rate with negligible late loss by angiography. By IVUS, beta-radiation was shown to inhibit neointima formation, with no reduction of total vessel area at 6-month follow-up.

Efficacy of beta radiation in prevention of post-angioplasty restenosis. An interim report from the beta energy restenosis trial

Restenosis remains a major limitation of coronary angioplasty in spite of major advances in techniques and technology. Recent studies have demonstrated that ionizing radiation may limit the degree of this problem. Gamma radiation has been shown to be effective in reducing in stent restenosis in humans, and beta radiation following encouraging results in animals has been shown to be feasible in humans. The objective of this study was to assess the feasibility of a 5 F non-centered catheter to deliver beta radiation emitting seeds to the lesion site post angioplasty and its effect on restenosis. Following successful angioplasty, patients were randomized to treatment with 12, 14 or 16 Gy at the angioplasty site. This was delivered with a 5 F non-centered catheter. Twelve beta radiation emitting seeds (90Sr/Y) were delivered to an area 3 cm in length to cover the angioplasty site. Angiographic follow-up was performed at 6 months. Baseline and follow-up angiograms were performed by blinded investigators at a core laboratory. This interim report comprises the first 35 patients to complete 6-month angiographic follow-up. There were no major radiation incidents. Four patients had evidence of angiographic restenosis. The MLD (mm) and percent stenosis were 0.77 +/- 0.27/72.5 +/- 8.6 pre angioplasty, 2.08 +/- 0.4/25.7 +/- 9.8 post angioplasty and radiation and 2.05 +/- 0.59/25.7 +/- 19.8 at follow-up respectively.

CONCLUSION

Beta radiation can be feasibly and safely delivered post coronary angioplasty with a very encouraging reduction of restenosis.

Panic disorder in coronary artery disease patients with noncardiac chest pain

In this study we address the following questions: (1) What percentage of coronary artery disease (CAD) patients that present with chest pain, but whose symptoms cannot be fully explained by their cardiac status, suffer from panic disorder (PD)? (2) How do patients with both CAD and PD compare to patients without CAD and to patients without either PD or CAD in terms of psychological distress? Four hundred forty-one consecutive walk-in emergency department patients with chest pain underwent a structured psychiatric interview (ADIS-R) and completed psychological scales. Fifty-seven percent (250 of 441) of these patients were diagnosed as having noncardiac chest pain and constituted this study's sample. A total of 30% (74 of 250) of noncardiac chest pain patients had a documented history of CAD. Thirty-four percent (25 of 74) of CAD patients met criteria for PD. Patients with both PD and CAD displayed significantly more psychological distress than CAD patients without PD and patients with neither CAD nor PD. However, they did not differ from non-CAD patients with PD. PD is highly prevalent in patients with CAD that are discharged with noncardiac diagnoses. The psychological distress in these patients appears to be related to the panic syndrome and not to the presence of the cardiac condition.

Panic disorder in emergency department chest pain patients: prevalence, comorbidity, suicidal ideation, and physician recognition

PURPOSE

To establish the prevalence of panic disorder in emergency department (ED) chest pain patients; compare psychological distress and recent suicidal ideation in panic and non-panic disorder patients; assess psychiatric and cardiac comorbidity; and examine physician recognition of this disorder.

DESIGN

Cross-sectional survey (for psychiatric data). Prospective evaluation of patient discharge diagnoses and physician recognition of panic disorder.

SETTING

The ambulatory ED of a major teaching hospital specializing in cardiac care located in Montreal, Canada.

SUBJECTS

Four hundred and forty-one consenting, consecutive patients consulting the ED with a chief complaint of chest pain.

PRIMARY OUTCOME MEASURE

Psychiatric diagnoses (AXIS I). Psychological and pain test scores, discharge diagnoses, and cardiac history.

RESULTS

Approximately 25% (108/441) of chest pain patients met DSM-III-R criteria for panic disorder. Panic disorder patients displayed significantly higher panic-agoraphobia, anxiety, depression, and pain scores than non-panic disorder patients (P < 0.01). Twenty-five percent of panic disorder patients had thoughts of killing themselves in the week preceding their ED visit compared with 5% of the patients without this disorder (P = 0.0001) even when controlling for co-existing major depression. Fifty-seven percent (62/108) panic disorder patients also met criteria for one or more current AXIS I disorder. Although 44% (47/108) of the panic disorder patients had a prior documented history of coronary artery disease (CAD), 80% had atypical or nonanginal chest pain and 75% were discharged with a "noncardiac pain" diagnosis. Ninety-eight percent of the panic patients were not recognized by attending ED cardiologists.

CONCLUSIONS

Panic disorder is a significantly distressful condition highly prevalent in ED chest pain patients that is rarely recognized by physicians. Nonrecognition may lead to mismanagement of a significant group of distressed patients with or without coronary artery disease.

Is cardiac migraine a clinical entity?

Chest pain because of a disorder of the coronary circulation is assumed to be ischemic in nature. Irrespective of the underlying pathophysiological mechanism, it is accepted that all routes lead to myocardial ischemia in the pathway to anginal pain. The authors describe a patient with a history of vasoactive disorders including migraine, asthma, documented variant angina with prolonged episodes of chest pain, and scintigraphic evidence of inferior and posterior wall ischemia during exercise and ergonovine testing in the absence of significant underlying stenoses. Remarkably, severe retrosternal chest pain, ST segment depression in multiple leads, and relative increased uptake in the inferior and posterior walls on Tc-99m sestamibi tomographic images developed during pharmacologic coronary vasodilatation with dipyridamole, leading the authors to speculate as to the possible existence of a nonischemic chest pain syndrome caused by coronary vasodilatation either in association with variant angina or as a separate entity.

Structural – compositional variation in three age-classes of temperate rainforests in southern coastal British Columbia

Relationships between forest structure and species composition were examined in three age-classes of temperate rain forest in southern coastal British Columbia. Old forests (> 250 years) exhibited greater structural and compositional heterogeneity than young (31–60 years) and mature (61–80 years) forests. Size-class distributions of living and dead standing trees in the three age groups suggested both qualitative and quantitative differences in regeneration and mortality processes. The canonical correlation between structure and composition was high (Rc = 0.84), but a substantial amount of total variation remained unexplained by the analysis. Principal component analysis (PCA) axis 1 of species composition separated the lower elevation (warmer and drier) mature forests from the higher elevation (cooler and wetter) young and old forests. PCA axis 1 of structure separated the young and mature forests as a group from the old forests. PCAs of the separate age-classes indicated weaker compositional – structural linkages than with all age-classes combined. Study area differences explained greater proportions of variation in young and mature forests (up to 53%) than in old forests (< 10%). The results indicate a slow recovery process following impacts from human disturbance in coastal forests. Key words: canonical correlation analysis, old-growth temperate rain forest, principal component analysis, species composition, forest structure.

Time course of technetium-99m sestamibi myocardial distribution in dogs with a permanent or transient coronary occlusion

The influence of duration of coronary occlusion and reperfusion on technetium-99m hexakis-2-methoxyisobutylisonitrile (99mTc-sestamibi) myocardial redistribution between necrotic, salvaged and non-ischaemic myocardium was investigated in dogs submitted either to a 90-min or a 24-h permanent left descending coronary artery occlusion (groups 1 and 2) or to a 90-min occlusion followed by 30 min, 6 h or 22.5 h of reperfusion (groups 3, 4 and 5). In all groups, 99mTc-sestamibi and radiolabelled microspheres were injected at 45 min of occlusion. After delimiting the area at risk and the infarct by Evans blue perfusion and triphenyltetrazolium chloride staining, radioactivity of heart slices from normal, viable-ischaemic and necrotic myocardium was measured in a gamma counter. A significant (P < 0.001) linear relationship between 99mTc-sestamibi distribution and myocardial blood flow was observed in the area at risk of groups 1 (r = 0.92), 2 (r = 0.84), 3 (r = 0.90), 4 (r = 0.93) and 5 (r = 0.58). In all groups, the mean percentage of 99mTc-sestamibi uptake in the ischaemic over normal zone overestimated significantly (P < 0.05) the mean percentage of the ratio in myocardial blood flow measured with microspheres (group 1: 13.3 +/- 1.4 vs. 7.7 +/- 1.2; group 2: 15.9 +/- 2.0 vs 5.6 +/- 1.2; group 3: 14.9 +/- 1.6 vs 6.2 +/- 1.0; group 4: 20.9 +/- 1.7 vs 10.9 +/- 1.8; group 5: 51.0 +/- 2.7 vs 14.0 +/- 2.0).(ABSTRACT TRUNCATED AT 250 WORDS)