Towards automated detection of psychosocial risk factors with text mining

Background

Psychosocial risk factors influence early retirement and absence from work. Health checks by occupational health nurses (OHNs) may prevent deterioration of work ability. Health checks are documented electronically mostly as free text, and therefore the effect of psychological risk factors on working capacity is difficult to detect.

Aims

To evaluate the potential of text mining for automated early detection of psychosocial risk factors by examining health check free-text documentation, which may indicate medical statements recommending early retirement, prolonged sick leave or rehabilitation. Psychosocial risk factors were extracted from OHN documentation in a nationwide occupational health care registry.

Methods

Analysis of health check documentation and medical statements regarding pension, sick leave and rehabilitation. Annotations of 13 psychosocial factors based on the Prima-EF standard (PAS 1010) were used with a combination of unsupervised machine learning, a document search engine and manual filtering.

Results

Health check documentation was analysed for 7078 employees. In 83% of their health checks, psychosocial risk factors were mentioned. All of these occurred more frequently in the group that received medical statements for pension, rehabilitation or sick leave than the group that did not receive medical statement. Documentation of career development and work control indicated future loss of work ability.

Conclusions

This study showed that it was possible to detect risk factors for sick leave, rehabilitation and pension from free-text documentation of health checks. It is suggested to develop a text mining tool to automate the detection of psychosocial risk factors at an early stage.

P314 The functional effects of intramural course of coronary arteries by two-dimensional speckle-tracking dobutamine stress

Background

Intramural course of a coronary artery is a common anatomic variant, especially in the left anterior descending coronary artery (LAD). However, its effect on the myocardial function during stress remains still unclear.

Purpose

We compared regional myocardial strain measured by speckle tracking during dobutamine stress echocardiography (DSE) in patients with or without intramural course of the LAD.

Methods

Fifty patients (63 ±7 years) were prospectively enrolled and underwent DSE, computed tomography angiography (CTA), quantitative 15-Oxygen water positron emission tomographic perfusion imaging (PET), and invasive angiography. Patients with superficial (>1 mm) or deep (>2 mm) intramural course in the LAD were identified using CTA. Regional longitudinal strain and strain rate (LS, LSr), circumferential strain and strain rate (CS, CSr), as well as radial strain and strain rate (RS, RSr) were measured at rest, at a dobutamine dose of 20 mg/kg/min, at peak stress, and at early recovery (1 min after stress). Obstructive coronary artery disease (CAD) was defined as >75% stenosis or 40% to 75% stenosis combined with either fractional flow reserve < 0.80 or ischemia on PET.

Results

Intramural course of the LAD was detected in 17 patients. Of these, 8 patients had obstructive CAD and were excluded. Thus, 9 patients with intramural course and 11 controls without intramural course or obstructive CAD in the LAD were included. Myocardial strain and strain rate in the myocardial territory distal to intramural segment were similar to those in controls at rest, dobutamine stress and early recovery (Figure). Furthermore, there were no significant differences, at all time points, between the regional strain values of the myocardial segments those distal to the superficial and deep intramural course. In the myocardium distal to an intramural coronary segment, regional myocardial flow measured by PET during adenosine stress correlated with the regional LS (r = 0.80, p = 0.004), LSr (r = 0.66, p = 0.03), and CS (r = 0.69, p = 0.02) and RS (r = 0.53, p = 0.07) at the peak dobutamine stress. However, there was no correlation between flow and strain at rest.

Conclusions

Myocardial strain is not consistently affected in patients with intramural course of the LAD during dobutamine stress as assessed by speckle tracking echocardiography. Larger studies are warranted to evaluate whether certain anatomical variants cause abnormalities in systolic myocardial strain.

Abstract P314 Figure.

Health check documentation of psychosocial factors using the WAI

Background

Health checks in occupational health (OH) care should prevent deterioration of work ability and promote well-being at work. Documentation of health checks should reflect and support continuity of prevention and practice.

Aims

To analyse how OH nurses (OHNs) undertaking health checks document psychosocial factors at work and use the Work Ability Index (WAI).

Methods

Analysis of two consecutive OHN health check records and WAI scores with statistical analyses and annotations of 13 psychosocial factors based on a publicly available standard on psychosocial risk management: British Standards Institution specification PAS 1010, part of European Council Directive 89/391/EEC, with a special focus on work-related stress and workplace violence.

Results

We analysed health check records for 196 employees. The most frequently documented psychosocial risk factors were home-work interface, work environment and equipment, job content, workload and work pace and work schedule. The correlations between the number of documented risk and non-risk factors and WAI scores were significant: OHNs documented more risk factors in employees with lower WAI scores. However, documented psychosocial risk factors were not followed up, and the OHNs' most common response to detected psychosocial risks was an appointment with a physician.

Conclusions

The number of psychosocial risk factors documented by OHNs correlated with subjects' WAI scores. However, the documentation was not systematic and the interventions were not always relevant. OHNs need a structure to document psychosocial factors and more guidance in how to use the documentation as a tool in their decision making in health checks.

Allergic sensitization is associated with rhinovirus-, but not other virus-, induced wheezing in children

BACKGROUND

Data on the link between atopy and viral wheeze are limited.

AIM

To evaluate the association between IgE sensitization and viral infection in wheezing children.

METHODS

This is an observational study in hospitalized wheezing children (n = 247; median age 1.6 ; interquartile range 1.1, 2.9). Eighteen respiratory viral infections were studied using all available methods. A specific immunoglobulin E (IgE) sensitization for common food and aeroallergens and other atopy-related variables including total IgE, blood and nasal eosinophils, exhaled nitric oxide, eczema and atopic eczema, parental allergy and asthma, number of wheezing episodes, positive asthma predictive index or asthma and use of inhaled corticosteroid were correlated with specific viral etiology.

RESULTS

Atopy was closely associated with sole rhinovirus etiology (n = 58) but not with sole respiratory syncytial virus, sole enterovirus, sole human bocavirus, sole other virus, mixed viral, or virus negative etiology. The number of sensitizations was particularly associated with sole rhinovirus etiology (odds ratio 4.59; 95% confidence interval 1.78, 11.8; adjusted to age and sex), followed by aeroallergen sensitization (respectively; 4.18; 2.00, 8.72), total IgE level (2.06; 1.32, 3.21), food allergen sensitization (2.02; 1.08, 3.78), and nasal eosinophil count (1.52; 1.08, 2.13).

CONCLUSIONS

According to our data, allergic sensitization is positively linked to rhinovirus-, but not other virus-, associated wheezing and calls attention for studies to test rhinovirus-associated wheezing as a part of asthma risk indices.

A novel g.-1258G>A mutation in a conserved putative regulatory element of PAX9 is associated with autosomal dominant molar hypodontia

Mutations in the transcription factor PAX9 which plays a critical role in the switching of odontogenic potential from the epithelium to the mesenchyme during tooth development cause autosomal dominant non-syndromic hypodontia primarily affecting molars. Linkage analysis on a family segregating autosomal dominant molar hypodontia with markers flanking and within PAX9 yielded a maximum multipoint LOD score of 3.6. No sequence variants were detected in the coding or 5'- and 3'-untranslated regions (UTRs) of PAX9. However, we identified a novel g.-1258G>A sequence variant in all affected individuals of the family but not in the unaffected family members or in 3088 control chromosomes. This mutation is within a putative 5'-regulatory sequence upstream of PAX9 highly conserved in primates, somewhat conserved in ungulates and carnivores but not conserved in rodents. Bioinformatics analysis of the sequence determined that there was no abolition or creation of a putative binding site for known transcription factors. Based on our previous findings that haploinsufficiency for PAX9 leads to hypodontia, we postulate that the g.-1258G>A variant reduces the expression of PAX9 which underlies the hypodontia phenotype in this family.

Cardiac Positron Emission Tomography/Computed Tomography Imaging Accurately Detects Anatomically and Functionally Significant Coronary Artery Disease

Background— Computed tomography (CT) is increasingly used to detect coronary artery disease, but the evaluation of stenoses is often uncertain. Perfusion imaging has an established role in detecting ischemia and guiding therapy. Hybrid positron emission tomography (PET)/CT allows combination angiography and perfusion imaging in short, quantitative, low-radiation-dose protocols.

Methods and Results— We enrolled 107 patients with an intermediate (30% to 70%) pretest likelihood of coronary artery disease. All patients underwent PET/CT (quantitative PET with 15 O-water and CT angiography), and the results were compared with the gold standard, invasive angiography, including measurement of fractional flow reserve when appropriate. Although PET and CT angiography alone both demonstrated 97% negative predictive value, CT angiography alone was suboptimal in assessing the severity of stenosis (positive predictive value, 81%). Perfusion imaging alone could not always separate microvascular disease from epicardial stenoses, but hybrid PET/CT significantly improved this accuracy to 98%. The radiation dose of the combined PET and CT protocols was 9.3 mSv (86 patients) with prospective triggering and 21.8 mSv (21 patients) with spiral CT.

Conclusion— Cardiac hybrid PET/CT imaging allows accurate noninvasive detection of coronary artery disease in a symptomatic population. The method is feasible and can be performed routinely with <10 mSv in most patients.

Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT00627172.

Identification of ALOX5 as a gene regulating adiposity and pancreatic function

AIMS/HYPOTHESIS

We previously used an integrative genetics approach to demonstrate that 5-lipoxygenase (5-LO) deficiency in mice (Alox5 (-/-)) protects against atherosclerosis despite increasing lipid levels and fat mass. In the present study, we sought to further examine the role of 5-LO in adiposity and pancreatic function.

METHODS

Alox5 (-/-) and wild-type (WT) mice were characterised with respect to adiposity and glucose/insulin metabolism using in vivo and in vitro approaches. The role of ALOX5 in pancreatic function in human islets was assessed through short interfering RNA (siRNA) knockdown experiments.

RESULTS

Beginning at 12 weeks of age, Alox5 (-/-) mice had significantly increased fat mass, plasma leptin levels and fasting glucose levels, but lower fasting insulin levels (p<0.05). Although Alox5 (-/-) mice did not exhibit insulin resistance, they had impaired insulin secretion in response to a bolus glucose injection. Histological analyses revealed that Alox5 (-/-) mice had increased islet area, beta cell nuclear size, and numbers of beta cells/mm(2) islet (p<0.05), indicative of both hyperplasia and hypertrophy. Basal and stimulated insulin secretion in isolated Alox5 (-/-) islets were significantly lower than in WT islets (p<0.05) and accompanied by a three- to fivefold decrease in the expression of the genes encoding insulin and pancreatic duodenal homeobox 1 (Pdx1). Direct perturbation of ALOX5 in isolated human islets with siRNA decreased insulin and PDX1 gene expression by 50% and insulin secretion by threefold (p<0.05).

CONCLUSIONS/INTERPRETATION

These results provide strong evidence for pleiotropic metabolic effects of 5-LO on adiposity and pancreatic function and may have important implications for therapeutic strategies targeting this pathway for the treatment of cardiovascular disease.

Transoesophageal echocardiography in selecting patients for anticoagulation after ischaemic stroke or transient ischaemic attack

OBJECTIVES

To investigate prospectively the role of transoesophageal echocardiography (TEE) in selecting patients for anticoagulation in an unselected stroke population.

METHODS

Transthoracic echocardiography (TTE) and TEE were done in all clinically suitable hospitalised patients (n = 457) with transient ischaemic attack or ischaemic stroke in the acute phase during a two year period in Turku University Hospital. 441 patients were successfully evaluated for cardiac sources of embolism using TEE within 31 days of the event.

RESULTS

A major risk factor for a cardiac source of embolism excluding atrial fibrillation, acute myocardial infarction, and prosthetic valve was detected in 10% of patients and a minor risk factor for a cardiac source of embolism in 46%. When a major risk factor of a cardiac source of embolism was detected using TTE or TEE and no contraindications were present, the patient was given anticoagulation drugs. If a minor risk factor for a cardiac source of embolism was detected, anticoagulation treatment was started after clinical assessment, if no contraindications were present. In 62 (14%) cases, the patient was given oral anticoagulation drugs or the necessity of ongoing anticoagulation treatment was confirmed on the basis of TEE. When these anticoagulation treated patients were evaluated using logistic regression analysis, they were found to have significantly more atrial fibrillation and histories of myocardial infarctions. Moreover, the patients were mainly men. When patients in sinus rhythm and without any history of cardiac disease were analysed, 8% of patients were found to have been given anticoagulation drugs on the basis of TEE data.

CONCLUSION

This study suggests that TEE should be used in patients with stroke even without any clinical evidence of cardiac disease when the patients are candidates for anticoagulation.

Effect of medroxyprogesterone on pulmonary arterial pressure, exhaled nitric oxide, ECG and arterial blood gases

OBJECTIVES

To evaluate the effect of medroxyprogesterone acetate (MPA) therapy on pulmonary arterial pressure (PAP), exhaled nitric oxide (NO), electrocardiogram (ECG), and on arterial blood gases (ABG).

DESIGN

A double-blind randomized placebo-controlled cross-over trial.

SETTING

University hospital in Turku, Finland.

SUBJECTS

Fourteen postmenopausal women with respiratory impairment.

INTERVENTIONS

A 2-week placebo and a 2-week MPA period (60 mg day -1) followed by 6-week placebo or MPA washout periods.

MAIN OUTCOME MEASURES

The systolic PAP was estimated by Doppler echocardiography. PAP, ECG, NO and ABG were monitored at baseline, after 2-week placebo and MPA periods, and after 3- and 6-week placebo and MPA washout periods.

RESULTS

The mean PaCO2 at baseline was 5.4 +/- 0.6 kPa (mean +/- SD). The average decrease of PaCO2 on MPA was -0.8 +/- 0.3 kPa (P < 0.001) and 0.3 +/- 1.0 kPa (P = 0.007) at the 3-week washout. The mean systolic PAP at baseline was 44.3 +/- 14.5 mm Hg. MPA did not change PAP until the 6-week washout, when the average increase of + 6.9 +/- 19.8 mm Hg (P = 0.002) was observed. No changes occurred in PaO2, exhaled NO or the ECG axes. The PR interval was shorter only on MPA (15.9 +/- 27.0 ms, P = 0.020) whereas the QRS duration remained shorter up to 3-week washout (3.9 +/0 5.5 ms, P = 0.008 and 4.0 +/- 14.3 ms, P = 0.032). The systolic and diastolic BP and the heart rate did not change.

CONCLUSIONS

Despite prolonged decrease in PaCO2, short-term MPA had no effect on exhaled NO and did not decrease systolic PAP in postmenopausal women with respiratory impairment. MPA shortened the PR interval and the QRS duration, the latter effect being sustained at least up to 3 weeks.

Population-based twin study of the effects of migration from Finland to Sweden on endothelial function and intima-media thickness

Finnish men have higher coronary heart disease (CHD) mortality than Swedish men do. To assess the impact of migration to a country with lower CHD mortality on subclinical atherosclerosis, we measured early functional and structural atherosclerotic vascular changes in twins discordant for migration from Finland to Sweden. Conventional CHD risk factors, flow-mediated dilatation (FMD) of the brachial artery, carotid intima-media thickness, and carotid artery compliance were measured in 74 male twin pairs (20 monozygous, 54 dizygous), aged 42 to 69 years, in which co-one twin had migrated more than 20 years ago permanently to Sweden. There were no significant differences in CHD risk factors except for diastolic blood pressure and body fat percentage, which were higher in Sweden. In all subjects, mean FMD was non-significantly higher in Sweden (5.7+/-4.3% vs 4.9+/-4.2%, P=0.22), but in monozygous twins the difference in FMD was highly significant (7.2+/-4.4 vs 3.7+/-2.9%, P=0.003). There was no significant difference in intima-media thickness or carotid artery compliance between Sweden and Finland. We conclude that in Finnish monozygous twins the endothelial function is better among the twins that have migrated to a country with lower CHD prevalence.

Transthoracic color Doppler echocardiography: a new way to diagnose coronary artery disease

Until now, transthoracic echocardiography (TTE) has had the capability to visualize only the proximal portions of the main coronary arteries. However, we noticed that transthoracic color Doppler echocardiography has marked potential to visualize flow in the coronary arteries. In clinical cases we tested whether this method is useful for visualizing stenoses and flow even in peripheral branches of the coronaries. This article presents two illustrative clinical cases. In our experience, transthoracic color Doppler echocardiography is very suitable for clinical use.

Reduced myocardial flow reserve relates to increased carotid intima-media thickness in healthy young men

Increased carotid artery wall thickness and lipoprotein oxidation are key early events in atherosclerosis. To test the hypothesis that reduced myocardial flow reserve is a marker of subclinical atherosclerosis, we examined the relationships between flow reserve and carotid artery intima-media thickness (IMT) in young men free from coronary heart disease. Basal and dipyridamole stimulated coronary blood flow was measured using positron emission tomography (PET) in 55 healthy men aged 36+/-4 years. Myocardial flow reserve was calculated as the ratio of stimulated flow to basal flow. The mean carotid artery IMT was measured using high-resolution ultrasound. Oxidised LDL was measured as baseline LDL diene conjugation. Myocardial flow reserve decreased across the quartiles of increasing IMT (P=0.006), and was 5.2+/-1.9 in the lowest quartile for IMT and 3.7+/-1.2 in the highest (P=0.04, I vs. IV quartile). In univariate analysis, oxidised LDL correlated inversely with flow reserve (r=-0.35, P=0.01) and directly with IMT (r=0.51, P<0.001). The association between flow reserve and IMT remained significant (P< or =0.01) in multivariate regression model including age, blood pressure, left ventricular mass, ox-LDL, total cholesterol, HDL-cholesterol and triglycerides as covariates. These data support the concept that reduced myocardial flow reserve reflects subclinical atherosclerosis in asymptomatic subjects, and suggest that increased lipoprotein oxidation is directly related to early structural and functional atherosclerotic vascular changes.

Long-term reproducibility of ambulatory blood pressure in unselected elderly subjects

The aim of this study was to evaluate the long-term reproducibility and validity of 24-h ambulatory blood pressure measurements (ABPM) in an unselected elderly population. In a rural Finnish community 503 randomly chosen invited persons over 65 years of age participated and went through 24-h ABPM. As part of the validation of the methodology, the reproducibility study was conducted in 26 persons (age 65-76 years). Two identical sets of measurement were performed at 4-12 (median 8) month intervals. The agreement between measurements was assessed by correlation coefficients and standard deviation (SD) of the differences. There were no significant differences in 24-h, daytime and night-time average diastolic blood pressure (DBP) and daytime average systolic blood pressure (SBP) between the two measurements. During the second measurement, 24-h SBP and night-time average SBP were slightly higher than those obtained by the first monitoring. Average 24-h SBP and DBP were 18 and 7 mmHg lower, respectively, than office blood pressure averages. The correlation coefficients were significantly higher for 24-h ambulatory blood pressure than for office blood pressure. The SD of the mean difference between visits was significantly lower for 24-h ambulatory blood pressure than for office blood pressure measurements. These findings show that the long-term reproducibility of ambulatory blood pressure is good in an elderly unselected population and better than the office blood pressure reproducibility.

Coronary flow reserve: measurement with transthoracic Doppler echocardiography is reproducible and comparable with positron emission tomography

Detection of early vascular changes indicated by lowered coronary flow reserve (CFR) would allow early treatment and prevention of atherosclerosis. The purpose of this study was to test whether it is possible to reproducibly measure CFR with transthoracic Doppler echocardiography (TTE) in healthy volunteers. We measured CFR using dipyridamole infusion in ten healthy male volunteers with two methods: TTE and positron emission tomography (PET) with oxygen-15-labelled water (group A). However, CFR was assessed twice with TTE in eight healthy male volunteers (group B) to study the reproducibility of this method. We compared CFRs obtained using TTE flow measurements in the left anterior descending coronary artery (LAD) and PET flow measurements in the corresponding myocardial area. Coronary flow in LAD could be measured in all subjects using TTE. By TTE, an average CFR based on peak diastolic flow velocity (PDV) was 2.72 +/- 1.16, mean diastolic flow velocity (MDV) 2.56 +/- 1.06 and velocity time integral (VTI) 1.87 +/- 0.49. The results were reproducible in two repeated TTE studies (coefficient of variation in MDV 6.1 +/- 4.3%, n=8). By PET, CFR was 2.52 +/- 0.84. CFR assessed by TTE correlated closely with that measured by PET (MDV r=0.942, P<0.001; PDV r=0.912, P<0.002 and VTI r=0.888, P<0.006) and intraclass correlation was 0.929 (MDV) and tolerance limits for differences of CFRs was -0.78 to 0.72. We show that CFR measured by TTE has an excellent correlation with CFR measured by PET. We also found that TTE measurements of CFR were highly reproducible.

Epidural infusion of bupivacaine and fentanyl reduces perioperative myocardial ischaemia in elderly patients with hip fracture--a randomized controlled trial

BACKGROUND

Perioperative myocardial ischaemia is an important risk factor for cardiac morbidity and mortality after noncardiac surgery. The impact of analgesic management on the incidence and severity of cardiac ischemia was studied in 77 elderly patients undergoing surgical treatment of traumatic hip fracture.

METHODS

After hospital admission and written consent, patients were randomised to conventional analgesic regimen (intramuscular oxycodone, OPI group) or continuous epidural infusion of bupivacaine/fentanyl (EPI group). The analgesic regimens were started preoperatively. Patients were operated under spinal anaesthesia and the treatments were continued three days postoperatively. ECG was continuously recorded. ST segment depression of > or = 0.1 mV or elevation of > or = 0.2 mV lasting > or = 1 min were considered as ischaemic episodes. Nocturnal arterial oxygen saturation (SaO2) was recorded perioperatively, and subjective pain was assessed every morning using a visual analogue scale (VAS).

RESULTS

Fifty-nine (OPI 30, EPI 29) patients were evaluable for efficacy. Thirteen patients (43%) in the OPI and 12 patients (41%) in the EPI group had ischaemic episodes (NS). However, significantly more patients in the OPI group had ischaemic episodes during the surgery (8 vs. 0 in the EPI group, P=0.005). The median (quartal deviation) total ischaemic burden (i.e. integral of ST-change vs. time) in patients with ischaemic episodes was ten times larger in the OPI group (340 [342] mm x min) compared with the EPI group (30 [36] mm x min) (P=0.002). There were no significant differences between the groups in average heart rates or in heart rates at the start of ischaemic episodes or in maximal heart rates during the attacks. Average nocturnal SaO2 was similar in the two groups and there were no differences in the number of hypoxaemic (SaO2<90%) episodes. Preoperatively there were no differences in subjective pain, but postoperative and average perioperative VAS scores for pain were almost 40% lower in the EPI group (P=0.006). Perioperative myocardial infarctions were not detected.

CONCLUSIONS

Continuous epidural bupivacaine/fentanyl analgesic regimen, started preoperatively, reduces the amount of myocardial ischaemia in elderly patients with hip fracture.

Reduced myocardial flow reserve does not impair exercise capacity in asymptomatic men

We examined whether impaired coronary flow reserve in healthy men is associated with changes in cardiac performance and exercise-induced ischemia. A comparison between 7 asymptomatic men with low flow reserve (<3.5) and 8 men with normal flow reserve (>3.5) showed no differences in these parameters, suggesting that the mechanisms that control myocardial blood flow during exercise remain normal despite the alterations in the mechanisms that control the vasodilatory reaction to dipyridamole.

Is routine echocardiography useful in patients hospitalized for chest pain? Evidence of areal myocardial dysfunction detected only by echocardiography

To assess the diagnostic value of routine two-dimensional echocardiography in the coronary care unit setting, we studied 81 unselected patients admitted for acute chest pain. Using electrocardiography (ECG), clinical history and serum markers of myocardial injury, the patients were retrospectively diagnosed as having had definite acute myocardial infarction (AMI) with (n=13) or without (n=31) previous infarction, possible AMI with (n=14) or without (n=15) previous infarction, and non-coronary cardiac or other causes of chest pain (n=8). Abnormal wall motion was observed in 75/77 patients with a cardiac origin of symptoms (sensitivity 97%), and there were no false-positive wall motion findings. In the 73 patients who were finally diagnosed with coronary artery disease (CAD), echocardiography showed wall motion abnormality in at least one additional coronary territory area in which there were no diagnostic ECG changes for 56% of patients with CAD (41/73) (P<0. 001). These areas were considered to be indicative of the presence of myocardium at risk for future cardiac events. We conclude that in addition to being a sensitive and accurate tool for detection of ischaemic wall motion abnormalities, two-dimensional echocardiography can give valuable information about the area of myocardium at risk. Therefore, therapeutic decisions can be affected by the findings of the routine echocardiographic examination, which is recommended even in unselected coronary care unit patients.

Genomewide scan for familial combined hyperlipidemia genes in finnish families, suggesting multiple susceptibility loci influencing triglyceride, cholesterol, and apolipoprotein B levels

Familial combined hyperlipidemia (FCHL) is a common dyslipidemia predisposing to premature coronary heart disease (CHD). The disease is characterized by increased levels of serum total cholesterol (TC), triglycerides (TGs), or both. We recently localized the first locus for FCHL, on chromosome 1q21-q23. In the present study, a genomewide screen for additional FCHL loci was performed. In stage 1, we genotyped 368 polymorphic markers in 35 carefully characterized Finnish FCHL families. We identified six chromosomal regions with markers showing LOD score (Z) values >1.0, by using a dominant mode of inheritance for the FCHL trait. In addition, two more regions emerged showing Z>2.0 with a TG trait. In stage 2, we genotyped 26 more markers and seven additional FCHL families for these interesting regions. Two chromosomal regions revealed Z>2.0 in the linkage analysis: 10p11.2, Z=3.20 (theta=.00), with the TG trait; and 21q21, Z=2.24 (theta=.10), with the apoB trait. Furthermore, two more chromosomal regions produced Z>2.0 in the affected-sib-pair analysis: 10q11.2-10qter produced Z=2.59 with the TC trait and Z=2.29 with FCHL, and 2q31 produced Z=2.25 with the TG trait. Our results suggest additional putative loci influencing FCHL in Finnish families, some potentially affecting TG levels and some potentially affecting TC or apoB levels.

Role of echocardiography in systemic arterial embolism. A review with recommendations

The ability of echocardiography to diagnose sources of embolism and the role of the examination in the prediction of thromboembolism are reviewed. In addition, the yield of transthoracic (TTE) and transoesophageal echocardiography (TEE) is analysed in patients with suspected embolism and guidelines are proposed for performing echocardiography in this setting. In general, echocardiography is reliable for diagnosing sources of embolism and this applies in particular to TEE in the case of atrial, valvular, and aortic abnormalities. However, the method is useful for predicting embolism in a few cases only. There is a substantial risk in the event of mobile or protruding thrombi, but screening for these and other markers of thromboembolism seems to be unproductive in most groups of risk patients. Yet, in the presence of atrial fibrillation, echocardiography may be helpful in defining patients with an otherwise normal heart and low risk of embolism--and in defining the relatively rare patient with a clinically low-risk profile but moderate-to-severe left ventricular systolic dysfunction and a high risk of embolism. TEE-guided conversion of atrial fibrillation without weeks of preceding anticoagulation may prove useful, after further investigation. The risk of embolism in relation to the size and mobility of valvular vegetations has remained controversial. In patients with suspected recent embolism, TTE results in less than 5% new therapeutic consequences. In those with a normal TTE, the yield of TEE seems to be equally low. We therefore recommend a selective strategy: TTE and TEE can be omitted when a cardiac source of embolism appears from the clinical setting and in most patients with an obvious predisposition to cerebrovascular disease. However, in the latter cases TTE should be performed if indicated by the clinical situation, e.g. in the presence of fever and murmur. TTE is also recommended when there are no obvious markers of primary vascular disease. To preclude very rare sources of embolism (e.g. atrial thrombi despite sinus rhythm), supplementary TEE is recommended in younger patients in whom primary vascular disease is very unlikely. The diagnosis by TEE of common conditions such as atrial septal aneurysms and patent foramen ovale cannot, however, be taken as proof of the mechanism of a systemic arterial occlusive event; thus it is difficult to change therapy on the basis of such diagnoses.

Circadian rhythm of frequency-domain measures of heart rate variability in pregnancy

OBJECTIVE

To examine frequency domain measures of heart rate variability and their circadian rhythms in pregnancy.

DESIGN

A longitudinal study.

SETTING

University hospital in Turku, Finland.

PARTICIPANTS

Sixteen healthy women between 11 and 27 weeks of pregnancy; 12 women before pregnancy; and four women postpartum.

MAIN OUTCOME MEASURES

Heart rate variability as measured in frequency domain from 24-hour ambulatory electrocardiography.

RESULTS

Pregnancy was associated with a lower standard deviation of R-R intervals (P < 0.01), with reduced very low (P < 0.05), low (P < 0.01), and high frequency (P < 0.05) power spectral components of heart rate variability. The high frequency power was lower at night in pregnancy, but similar in the daytime in pregnant and nonpregnant women.

CONCLUSIONS

Pregnancy is associated with an overall reduction in heart rate variability, most markedly reflected in the low frequency component. This suggests altered baroreflex or sympathetic modulation of heart rate, and decreased vagal activation at night.

Glucose uptake in the chronically dysfunctional but viable myocardium

BACKGROUND

The regulation of glucose uptake in the dysfunctional but viable myocardium has not been studied previously in humans.

METHODS AND RESULTS

Seven patients with an occluded major coronary artery but no previous infarction were studied twice with 2-[(18)F]fluoro-2-deoxy-D-glucose positron emission tomography, once in the fasting state and once during hyperinsulinemic euglycemic clamping. Myocardial blood flow was measured with [(15)O]H2O. The myocardial region beyond an occluded artery that showed stable wall-motion abnormality represented chronically dysfunctional but viable tissue. Six of the patients were later revascularized, and wall-motion recovery was detected in the corresponding regions, which confirmed viability. A slightly reduced myocardial blood flow was detected in the dysfunctional than in the remote myocardial regions (0.81 +/- 0.27 versus 1.02 +/- 0.23 mL x g(-1) x min(-1),P=.036). In the fasting state, glucose uptake was slightly increased in the dysfunctional regions compared with normal myocardium (15 +/- 10 versus 11 +/- 10 micromol/100 g per minute, P=.038). During insulin clamping, a striking increase in glucose uptake by insulin was obtained in both the dysfunctional and the normal regions (72 +/- 22 and 79 +/- 21 micromol/100 g per minute, respectively; P<.001, fasting versus clamping).

CONCLUSIONS

Contrary to previous suggestions, glucose uptake can be increased strikingly by insulin in chronically dysfunctional but viable myocardium. This demonstrates that insulin control over glucose uptake is preserved in the dysfunctional myocardium and provides a rational basis for metabolic intervention.

Exercise echocardiography in the diagnosis of coronary artery disease

The purpose of this study was to test the applicability of exercise echocardiography in the diagnosis of coronary artery disease. The results were compared to findings of coronary angiography. 118 patients, 100 males and 18 females, who were all referred to coronary angiography for suspected ischaemic heart disease, underwent exercise echocardiography using a cycle ergometer. At coronary angiography 108 patients had significant stenosis in at least one coronary artery. Ten patients had angiographically normal coronary arteries. A new or increased wall motion abnormality detected by echocardiography after the exercise was considered an ischaemic response. Of the 108 patients with coronary artery disease, 101 had abnormal exercise echocardiograms, and the overall sensitivity of exercise echocardiography in detecting ischaemic heart disease was 94%. Among the 10 patients without coronary artery disease, seven had normal and three had abnormal exercise echocardiograms, and the specificity of the test was 70%. In conclusion, exercise echocardiography is a reliable diagnostic method in screening of ischaemic heart disease, and it can be combined relatively easily with the exercise examinations.

Saline contrast and colour Doppler transoesophageal echocardiography in detecting a patent foramen ovale and right-to-left shunts in stroke patients

A paradoxical embolism due to right-to-left shunt through a patent foramen ovale (PFO) can be responsible for stroke and other ischaemic cerebral events. We studied the usefulness of saline contrast transoesophageal echocardiography after the Valsalva manoeuvre in detecting PFO and right-to-left shunts in 28 adult patients without known reason for a recent stroke. The results were compared with conventional transthoracic colour Doppler and with transoesophageal colour Doppler techniques. A PFO was found in 24 patients (86%) of our selected study population, whereas in four patients no PFO was found. A PFO with left-to-right shunt could be diagnosed by transthoracic colour Doppler echocardiography in only one case. A PFO with left-to-right shunt was found by transoesophageal colour Doppler echocardiography in 17 patients (61%), but in only three of them was a right-to-left shunt detected, even after the Valsalva manoeuvre. In contrast, a PFO with right-to-left shunt could be detected in 21 patients (75%) by using saline contrast transoesophageal echocardiography with the Valsalva manoeuvre. However, the method was unable to detect three cases of PFO with only left-to-right shunt, which were detected by colour Doppler transoesophageal echocardiography. In conclusion, our results show that saline contrast transoesophageal echocardiography with the Valsalva manoeuvre greatly improves the echocardiographic detection of PFO with right-to-left shunts in stroke patients.

Imaging of the heart by MRI and PET

This review article describes the clinical usefulness and future potential of two new methods for the imaging of the heart, which have recently also become available outside research laboratories. These methods are magnetic resonance imaging (MRI) and positron emission tomography (PET). MRI is the most rapidly increasing imaging modality in medicine today. The moving heart forms a challenge to conventionally rather slow MRI-techniques. Techniques based on ECG-gating have been mandatory in making cardiac cine-MRI possible. Even though MRI provides accurate and quantitative information of the heart, conventional methods are time-consuming, confined to special laboratories, and rather expensive. Therefore, the clinical use of cardiac MRI is, in many laboratories, limited to cases in which echocardiography does not provide adequate information (e.g. pulmonary circulation) or when the patient is not willing to have transoesophageal echocardiography for better visibility. MRI is also used instead of or to complement invasive angiography to study large vessels, and it provides excellent information on paracardiac masses. Cardiac MRI is developing rapidly and within the next few years it is likely to have a profound impact on cardiac imaging. This is based on its noninvasive nature and on the comprehensive anatomic (including coronary arteries), functional, flow, perfusion and possibly also metabolic information it has the potential to provide in a manner not comparable to any other imaging method. PET is a nuclear medicine imaging modality that allows quantitative characterization of a variety of physiological and metabolic processes in vivo. Using positron-emitting flow tracers and analogues of metabolic substrates, regional myocardial blood flow, glucose and fatty acid metabolism and oxygen consumption can be studied noninvasively by PET in research as well as in clinical practice. For example, regional myocardial glucose utilization rates can be measured accurately by PET. This allows us to study the effects of nutritional interventions, hormonal and neural effects as well as disease processes on the glucose utilization of the human heart. PET is currently the only technique that permits noninvasive quantification of regional myocardial perfusion in absolute terms. Over the last decade, PET has also emerged as a clinically useful tool to study coronary artery disease and myocardial viability.

Pre-excitation syndrome in Leber's hereditary optic neuropathy

Pre-excitation syndrome is common in families with Leber's hereditary optic neuropathy (LHON). 24 Finnish families with LHON were screened for the 11778 and the 3460 mitochondrial DNA mutations. 5 of 30 individuals with LHON and the 11778 mutation had the Wolff-Parkinson-White pre-excitation syndrome. None of 10 with the 3460 mutation or of 11 with "other" mutations had this syndrome. Overall, 5 of 51 LHON patients and 9 of 112 symptom-free maternal relatives had Wolff-Parkinson-White syndrome (9%). In paternal relatives, the frequency was 1.6%. Mitochondrial DNA causal for LHON may contribute to pre-excitation syndrome.

Enhancement of myocardial [fluorine-18]fluorodeoxyglucose uptake by a nicotinic acid derivative

Recently, the euglycemic hyperinsulinemic clamp technique was shown to give excellent image quality during metabolic steady-state conditions. Acipimox is a new potent nicotinic acid derivative that rapidly reduces serum free fatty acid (FFA) levels by inhibiting lipolysis in peripheral tissue.

METHODS

To compare the effects of acipimox administration and insulin clamp on [18F]fluorodeoxyglucose ([18F]FDG) uptake and myocardial glucose utilization, five nondiabetic and seven type II diabetic patients who had had previous myocardial infarctions were studied twice: once during a clamp study and once after the administration of acipimox (2 x 250 mg orally). All patients also underwent resting SPECT perfusion imaging prior to PET scans.

RESULTS

The patients tolerated acipimox well. Although fasting plasma glucose levels were higher in diabetic patients (9.2 +/- 3.4 versus 5.5 +/- 0.3 mM, p = 0.03), they were decreased both during clamping and after acipimox; during imaging, no significant differences between the groups and approaches were detected. By visual analysis, the image quality and myocardial [18F]FDG uptake patterns were similar during clamping and after acipimox. Compared with the relative [18F]FDG uptake values obtained during clamping, acipimox yielded similar results in normal, mismatch and scar segments (r = 0.88, p = 0.0001). Similar rMGU values were also obtained during both approaches.

CONCLUSION

Thus, PET imaging with [18F]FDG after the administration of acipimox is a simple and feasible method for clinical viability studies both in nondiabetic and diabetic patients. It results in excellent image quality and gives rMGU levels similar to the insulin clamp technique.

Comparison of cardiovascular reflex tests and blood pressure measurement in prediction of pregnancy-induced hypertension

A changed pressor response to some cardiovascular reflex tests and an increase in midtrimester blood pressure has been reported to precede the appearance of hypertension in pregnancy-induced hypertensive disorders (PIH). In order to compare the value of midtrimester blood pressure with the cardiovascular reflex tests, in predicting the risk of PIH, the Valsalva manoeuvre, the orthostatic test, the deep breathing test and the isometric handgrip test were performed prospectively in 94 women studied once at 21-29 weeks of pregnancy. Eight subjects developed PIH 3-12 weeks after the testing. The resting blood pressure in midpregnancy was related to PIH later in pregnancy. The most powerful measures were the supine diastolic resting blood pressure (odds ratio, 1.24; 95% confidence limits, 1.08-1.43) and the mean arterial pressure (odds ratio, 1.25; 95% confidence limits, 1.09-1.44). Signs of autonomic dysfunction were found in 37% of the patients developing PIH and in 8% of the healthy remaining subjects (P = 0.04). The results show that the preclinical stage of PIH is associated with some changes in the neural hemodynamic control. However, cardiovascular reflex tests do not add much information on the risk of PIH compared with measuring of the resting blood pressure during mid-pregnancy.

Evaluation of left ventricular volume and mass with breath-hold cine MR imaging

Left ventricular (LV) volumes and mass were evaluated in 10 healthy volunteers with breath-hold cine magnetic resonance (MR) imaging. The results were compared with those obtained with conventional cine MR imaging. The breath-hold studies showed no ghosting artifact, and cardiac edges were clearly identified because of the reduced blurring. Measurements of LV end-diastolic volume (LVEDV), LV end-systolic volume (LVESV), and LV mass obtained with breath-hold cine MR imaging showed close correlation with those obtained with conventional cine MR imaging (r = .98, .97, and .99, respectively). The interobserver variabilities for LVEDV, LVESV, and LV mass determined with breath-hold cine MR imaging (4.0%, 8.0%, and 3.7%, respectively) were equal to or less than those determined with conventional cine MR imaging (4.0%, 8.6%, and 5.0%, respectively). The authors conclude that breath-hold cine MR imaging is highly useful because an accurate assessment of cardiac function is obtained in less than 5 minutes.

Magnetic resonance imaging and spectroscopy of the human heart

Magnetic resonance imaging and spectroscopy have a great potential both for clinical cardiac diagnostics and for research in cardiac physiology, metabolism and disease. At the present time, cardiac MRI already is the method of choice in several clinical conditions, especially in imaging central vasculature and intra- and paracardiac masses. With the recent development of contrast agents and ability to measure both flow velocities and flow volume, the cardiac MRI is likely to have a profound role in evaluating coronary arterial disease as well as valvular heart disease. The limitations due to long imaging times of cardiac MRI-studies are likely to be overcome with the development of ultrafast imaging techniques in the near future. On the other hand, cardiac MRS is still a research tool, which needs technical improvements before it can be widely utilized in clinical work. However, attempts to this aim are highly justified, when the possibility that MRS will provide metabolic information of the heart is considered and bearing in mind, that MR-magnets with sufficient field strength for MRS are increasingly in use in most modern hospitals. The role of magnetic resonance imaging (MRI) and spectroscopy (MRS) in the evaluation of heart diseases is still evolving. Some clear indications for clinical use of cardiac MRI have already become apparent, whereas cardiac MRS is still confined to research applications. The current paper consists of a review of the role of MRI for cardiovascular diagnosis together with a review of the currents status of cardiac MRS.

MR imaging of the myocardium using nonionic contrast medium: signal-intensity changes in patients with subacute myocardial infarction

OBJECTIVE

Gadodiamide injection (Omniscan, Sanofi Winthrop Pharmaceuticals, New York) is a new nonionic MR contrast medium that has been shown in animal studies to provide persistent differential enhancement of myocardial infarction. Because differential enhancement of normal and infarcted myocardium may be useful for the diagnosis and sizing of myocardial infarctions, we assessed the effectiveness of gadodiamide injection in enhancing signal-intensity differences between infarcted and normal myocardium on spin-echo T1-weighted images.

SUBJECTS AND METHODS

Signal intensity of normal and infarcted myocardium, contrast ratio, contrast-to-noise ratio, and signal-to-noise ratio were measured in 12 patients with subacute myocardial infarction (mean, 16 days after diagnosis) before and after injection of contrast medium. Precontrast T1-weighted and T2-weighted images were obtained with a 1.5-T MR imager. T1-weighted images were acquired 5, 15, and 30 min after gadodiamide injection (0.2 mmol/kg) and T1-weighted images with fat saturation were acquired 10 min after gadodiamide injection.

RESULTS

Gadodiamide injection significantly increased signal intensity of normal (34 +/- %) and infarcted (90 +/- %) myocardium compared with their signal intensities on precontrast T1-weighted images. The contrast ratio was significantly increased, and the augmented ratios persisted throughout the 45-min observation period. The contrast ratio on T2-weighted images was comparable to that on contrast-enhanced T1-weighted images (with or without the use of fat saturation). However, the signal-to-noise and contrast-to-noise ratios of T2-weighted images were significantly lower than those of contrast-enhanced T1-weighted images. The maximum contrast-to-noise ratio for visualizing myocardial infarction was achieved on contrast-enhanced T1-weighted images with fat saturation.

CONCLUSION

Improved and persistent contrast between infarcted and normal myocardium can be produced on MR images by injecting gadodiamide at a dose of 0.2 mmol/kg, which provides prolonged delineation of myocardial infarctions. Maximum contrast-to-noise ratios for detecting myocardial infarction can be produced by using fat-saturated T1-weighted imaging after a high dose of this nonionic contrast medium has been administered.

Measurement of T1 relaxation times of cardiac phosphate metabolites using BIR-4 adiabatic RF pulses and a variable nutation method

T1 relaxation times of PCr and beta-ATP in human cardiac and skeletal muscle were evaluated using a variable nutation method. This allows T1 measurements with a constant TR and a significant reduction in acquisition time compared with the partial saturation method. Four 1D CSI datasets were obtained using 30 degrees, 45 degrees, 60 degrees, and 90 degrees BIR-4 adiabatic RF pulses within 40 min. The T1 of the phosphate phantom obtained with this method agreed with values obtained with the partial saturation method. The T1s of PCr and beta-ATP in heart are 3.98 +/- 0.18 s and 1.86 +/- 0.16 s (mean +/- SE). Our results demonstrated that T1 values in heart and skeletal muscle are not significantly different.

Assessment of left ventricular diastolic function in dilated cardiomyopathy with cine magnetic resonance imaging: effect of an angiotensin converting enzyme inhibitor, benazepril

The effects of angiotensin converting-enzyme inhibitor, benazepril, on diastolic function in patients with dilated cardiomyopathy, with (n = 4) or without (n = 11) mitral regurgitation, were examined with the time-volume curve of the left ventricle derived from cine magnetic resonance images. Peak filling rate/end-systolic volume and ejection fraction were increased in the group without regurgitation (p < 0.01) but not in the group with regurgitation after treatment. There was a strong correlation between peak filling rate/end-systolic volume and ejection fraction (r = 0.89) and between the change in peak filling rate/end-systolic volume and that in ejection fraction after treatment (r = 0.74) in the group without regurgitation. These findings suggest that in some patients with dilated cardiomyopathy benazepril has favorable effects on diastolic function, which seem to be related to improvement in systolic function. This drug may not be as beneficial in patients with dilated cardiomyopathy complicated by mitral regurgitation.

Radiographic pulmonary changes of gastro-oesophageal reflux disease in elderly patients

The aim of this study was to investigate the association of gastro-oesophageal reflux disease (GORD) with radiographic pulmonary changes. One hundred and thirty-seven patients aged over 60 years referred for endoscopy for abdominal symptoms were included in the study. In patients with any suspicion of GORD (n = 95), 24-hour oesophageal pH monitoring was carried out. All the patients were interviewed before the examinations. Chest radiography was performed in all patients. Odds ratio of respiratory symptoms was 8.7 (95% confidence interval 3.4-22.4) in patients with total reflux time of more than 10% compared with those who had total reflux time of less than 10%. In chest radiography, bilateral pleural adhesions and thickenings and bilateral parenchymal scars were significantly more common in patients with, than in those without, regurgitation or large hiatal openings. The occurrence of bilateral scars and pleural thickenings increased with the extent of gastro-oesophageal reflux in pH monitoring. Odds ratios of bilateral pleural thickening and pulmonary scars were 3.1 (95% confidence interval 0.8-11.5) and 5.8 (1.1-29.6) in patients with total reflux time over 10%, compared with patients who had normal total reflux time. The findings indicate that respiratory involvement is a characteristic feature of GORD in elderly patients.

Is there need for change of health examinations for sea pilots?

Sea pilots must be capable of carrying out their work in all situations. Thus, they must not have any disease or defect, that could impair their job performance. By periodic medical examinations attempts are made to ensure their working capacity. In most countries these examinations are carried out by a general practitioner and they include only few if any objective laboratory tests. The aim of the present investigation was to study the effectiveness of the periodic medical examinations to find out in the population of pilots examined persons with health risks, especially risks for cardiovascular diseases. All the pilots examined were over 45 years old (n = 135, response rate 88%). Self-evaluation of health was carried out by a questionnaire. Blood analyses were made and chest X-ray as well as exercise-ECC were taken. The most common subjective symptoms concerned musculoskeletal and gastrointestinal systems; sleep disturbances were also quite common. The three most frequent diseases diagnosed earlier by a doctor were musculoskeletal and gastrointestinal diseases, and arterial hypertension. About 24% of pilots had a lower physical working capacity than predicted. The body mass index indicated at least 11% overweight in half of the cases. At exercise-ECG four pilots appeared to have an ischaemic heart disease and additionally eleven pilots had abnormal ECG. Over 80% of pilots had a serum cholesterol value higher than 5 mmol/l, and serum triglyceride values exceeded the normal value of 2.0 mmol/l in every fourth case. Serum glutamyl transaminase was pathological in over 20% of the cases, and serum glucose level in 8%. The findings by routine physical examinations were very few consisting of stiffness in musculoskeletal system, two cases of elevated blood pressure, two heart murmurs, varicose veins etc. In two cases an inguinal hernia was suspected. The current periodic health examinations does not seem to effectively prevent a person with possible health defect from working as a sea pilot. More objective tests must be included in these examinations and more attention should be paid to prevention of overweight, effective treatment of musculoskeletal symptoms, improving physical working capacity and helping pilots to manage their psychic stress.

Acute hemodynamic effects of medetomidine and clonidine in healthy volunteers: a noninvasive echocardiographic study

Single intravenous (i.v.) doses of 4(5)-[1-(2,3-dimethylphenyl)ethyl]imidazole, medetomidine (MED), (25, 50, and 100 micrograms) and clonidine (CLO 200 micrograms) were administered to five healthy male volunteers in a randomized, double-blind, placebo-controlled, multiple cross-over study. The hemodynamic effects of the drugs were determined by a two-dimension Doppler-echocardiographic method. Blood pressure (BP) and heart rate (HR) were monitored noninvasively. Cardiac output (CO) was maximally reduced by 23% after 100 micrograms MED and 200 micrograms CLO. Dose-related decreases were observed in systolic BP (SBP) and diastolic BP (DBP) and HR. Maximal reductions were 18 and 11 mm Hg and 11 beats/min after 100 micrograms MED, and 18 and 13 mm Hg and 12 beats/min after CLO. Calculated total peripheral resistance (TPR) and the PR interval on ECG remained unchanged. Ejection fraction (EF) and stroke volume (SV) were not significantly affected by either drug, but mean circumferential fiber shortening velocity (VCF) and the preejection period/left ventricular ejection time (PEP/LVET) ratio indicated a tendency to slightly decreased myocardial performance. We conclude that the new selective alpha 2-adrenoceptor agonist, MED, resembles CLO in its acute hemodynamic actions in healthy humans.

Exercise thallium-201 scintigraphy in the localization of myocardial ischaemia

We performed a retrospective study in order to study the ability of thallium-201 exercise scintigraphy to detect and to localize coronary artery perfusion defects (in comparison with a recent coronary angiogram). We studied 81 patients (67 males); their average age was 52.3 years (men 50.5 and women 54.1 years). They performed a pulse-conducted cycle exercise test, and 2 min before end of exercise 75 MBq of thallium-201 was infused intravenously, and tomographic images were reconstructed by using a Siemens-Rota SPECT gamma camera immediately and 4 h after exercise. The thallium-201 uptake defects were attributed to different coronary arteries, and the results were compared with a coronary angiogram made afterwards in 48 patients. The groups of one-, two- and three-vessel disease were 27, 21, and 21 patients, and only 12 patients did not have significant (over 50%) stenoses. The latter had the highest ejection fraction and working capacity. Sensitivity of thallium-201 exercise scintigraphy was 65%, whereas that of exercise ECG was 41% in patients with a low ejection fraction, while in the whole material the sensitivity of thallium-201 scintigraphy was 91% and that of exercise ECG was 54%. A stenosis in the right coronary artery was best localized by the thallium-201 scintigram (86% correctly); a stenosis in the left anterior descending artery was localized correctly in 75% of the cases, but a stenosis in left circumflex artery was localized correctly only in 44%. We conclude that exercise thallium-201 scintigraphy is a useful method not only in detecting but also in localizing coronary artery disease.

Role of pulmonary diseases and physical condition in the regulation of vasoactive hormones

Lungs have many non-respiratory metabolic functions, of which some take place in the capillary endothelium, while others are in parenchymal lung tissue. We have studied the role of the lungs in the metabolism of vasoactive and some other hormones by comparing patients who have undergone lung resection to those having various obstructive or fibrotic lung diseases. We have also compared these groups with persons in good physical health. The data suggested that lung resection patients had low angiotensin II levels in plasma but the response of angiotensin II to exercise was normal. Also adrenalin concentration was low in the lung resection group while dopamine did not show any significant difference between the groups. When hormone levels were correlated to the exercise data, renin levels were especially related to physical condition. Serum post-exercise renin values were inversely related to the uneven distribution of lung perfusion, possibly thus reflecting the diminished pulmonary vascularization. A negative association was found between angiotensin II and diffusion capacity. Thus, the angiotensin II levels may preferably be controlled by the non-circulatory functions of the lungs.

Immunologic and nonimmunologic responsiveness in ragweed-sensitized dogs

The relationship between airway responsiveness to inhaled antigen and histamine, immunologic release of lung histamine, immunologic responsiveness of skin, and specific immunoglobulin E (IgE) antibodies were examined in 11 inbred allergic dogs immunized with extracts of ragweed and grass and 5 nonimmunized control dogs from the same colony. Airway responsiveness to antigen and histamine was characterized by the doses that increased the airflow resistance of the total respiratory system to twice the control values (ED200). Highly significant correlations were found between airway responsiveness and cutaneous responsiveness to antigen and other immunologic characteristics (e.g., IgE and histamine released from lung by inhaled antigen) in all dogs. In ragweed-sensitized dogs, there was an inverse correlation between immunologic responsiveness (reflected by the cutaneous response to antigen and histamine released from lung by inhaled antigen) and nonimmunologic responsiveness of airways (histamine ED200: r = 0.73, P less than 0.05 and r = 0.75, P less than 0.01, respectively). Antigen ED200 was also correlated with histamine release from lung after antigen inhalation (r = 0.74; P less than 0.01). We conclude that airway reactions to inhaled antigen in allergic dogs are dependent not only on immunologic factors but also on the degree of nonimmunologic airway responsiveness to histamine and that these factors are correlated inversely.

Airway responsiveness to inhaled antigen, histamine, and methacholine in inbred, ragweed-sensitized dogs

We studied the responses to antigen in animals selected from a colony of inbred dogs sensitized to specific allergens to determine if they had characteristics similar to those of human asthmatics. They were immunized with ragweed and grass pollen extracts (10 micrograms in alum) immediately after routine vaccination with attenuated live virus (distemper and hepatitis) and killed bacteria (Leptospira) at 4, 8, and 12 wk of age. Subsequently, ragweed and grass injections were repeated every 2 months. Immunized dogs made specific IgE-antibodies in serum averaging 3 to 4 times that of control animals (no immunization with pollen or vaccine). They showed positive skin responses to the injection of ragweed pollen extract, whereas control dogs did not respond to ragweed pollen by quantitative skin test or inhalation challenge. In immunized dogs under barbiturate anesthesia, air-flow resistance of the total respiratory system increased from 0.60 +/- 0.07 (mean +/- SEM) before to 12.6 +/- 3.4 cm H2O/lps 5 min after the start of antigen aerosol; respiratory resistance remained increased for 20 min and was associated with 0 hypoxemia and increased arterial plasma histamine. In addition, airway responsiveness to both inhaled histamine and methacholine was greater in immunized dogs than in nonimmunized dogs of comparable age. Airway responses to each agonist were highly reproducible on repeated testing. These results indicate that physiologic responses to antigen by inbred, ragweed-sensitized dogs resemble human asthma closely and that these dogs appear suitable for a variety of experimental studies of asthma with respect to pathogenesis, diagnosis, prevention, and treatment.

Cigarette smoke-induced bronchoconstriction in dogs: vagal and extravagal mechanisms

We reassessed the severity of cigarette smoke-induced bronchoconstriction and the mechanisms involved in anesthetized dogs. To evaluate the severity of smoke-induced bronchoconstriction, we measured airway pressure and airflow resistance (Rrs, forced oscillation method). We studied the mechanisms in other dogs by measuring airway pressure, central airway smooth muscle tone in tracheal segments in situ, and respiratory center drive by monitoring phrenic motor nerve output, including the role of vagal and extravagal nerves vs. the role of blood-borne materials during inhalation of cigarette smoke. Rrs increased more than fourfold with smoke from one cigarette delivered in two tidal volumes. About half the airway response was due to local effects of smoke in the lungs. The remainder was due to stimulation of the respiratory center, which activated vagal motor efferents to the airway smooth muscle. Of this central stimulation, about half was due to blood-borne materials and the rest to vagal pulmonary afferents from the lungs. We conclude that inhalation of cigarette smoke in dogs causes severe bronchoconstriction which is mediated mainly by extravagal mechanisms.

Development of the lipolytic activity in isolated perfused perinatal rabbit lungs and the influence of maternal cigarette smoke exposure on it

The ability of the lungs to release fatty acids from circulating triglycerides or lipoproteins for its own phospholipid synthesis may be one of the factors which limit the rate of surfactant formation. Therefore, the development of the lipolytic activity of lungs obtained from late fetal and neonatal rabbits has been studied and the results correlated to the phospholipid content of lungs of similar ages. Isolated lungs were perfused with a medium which contained cold and radioactive triglyceride, and the release of fatty acids into the perfusion medium was analyzed by both colorimetric and radiochemical methods. The phospholipids of the postmitochondrial supernatant fractions of the lungs were extracted and quantified by measuring inorganic phosphorus. Finally, the influence of maternal cigarette smoke exposure on the lipolytic activity of the lungs of their litters were studied. A high lipolytic activity in the lungs of 28-day-old fetuses was detected. The activity decreased towards birth, and was lowest on the first day after birth (about 20% of that observed in 28-day-old fetuses). However, it increased again during the first week after birth. Exposure of the mothers to cigarette smoke during the last 10 days before delivery did not affect the pulmonary lipolytic activity of the offspring. Although the lung phospholipid content increased 3.6-fold from 28 days of fetal life to 1 week after birth, it remained unchanged on the days when the lung lipolytic activity was lowest. We conclude that changes in lung lipolytic activity influence lung phospholipid synthesis, and consequently influence also surfactant formation in the lungs.

The metabolism of arachidonic acid to an antiaggregatory compound in isolated lungs of fetal and neonatal rabbits

The developmental pattern of fetal and neonatal rabbit lungs to generate an antiaggregatory compound from arachidonic acid (AA) was studied in isolated rabbit lungs, which were perfused with Krebs bicarbonate buffer. The antiaggregatory effect of the nonrecirculating perfusion effluent was tested by adding a small portion of the effluent to human platelet rich plasma (PRP) in a Born-type aggregometer before the aggregation was induced by ADP. The production of an antiaggregatory compound was minimal, when exogenous AA was not infused into the pulmonary circulation. When arachidonate (40 nmol/min) was infused into the pulmonary circulation of rabbits which were 1 day or 1 week old, the perfusion effluent significantly inhibited the ADP induced aggregation of PRP. Perfused lungs from fetal rabbits (gestation age 28-31 days) formed also an antiaggregatory compound from AA, but the antiaggregatory effect was not as great as 1 day after birth. It seems that neonatal rabbit lungs metabolize AA more to an antiaggregatory compound than late fetal lungs. The fact that the AA induced production of an antiaggregatory compound is inhibited by simultaneous infusion of indomethacin favours the hypothesis that this antiaggregatory compound could be PGI2.

The metabolism of arachidonic acid in isolated rat lungs is not changed during cigarette smoke ventilation

Cigarette smoke ventilation of isolated perfused rat lungs partially inhibited the pulmonary vascular pressor response to arachidonic acid. The amounts of metabolites of exogenous arachidonic acid in the perfusion effluent remained unchanged during smoke ventilation. The antiaggregatory effect of the effluent during pulmonary infusion of AA was not decreased by smoke ventilation. The cause of the previously reported increased platelet aggregation after smoking remains unclear.

The inactivation of prostaglandin E2 and 5-hydroxytryptamine in isolated perfused fetal and neonatal rabbit lungs

The inactivation of prostaglandin E2(PGE2) and 5-hydroxytryptamine (5-HT) was studied in isolated perfused lungs from fetal and neonatal rabbits. PGE2 inactivation was considerable already at the 28th day of fetal life, as only 11% of injected substrate survived passage through the pulmonary circulation. However, the inactivation increased significantly during the last 3 prenatal days (4% survival) and remained at this level when analyzed one week postnatally. In contrast to PGE2-metabolism, 5-HT inactivation was relatively stable during the studied fetal period (47-49% inactivation), but was decreased significantly on the 7th day postnatally when compared to newborn litters. The results indicate that pulmonary prostaglandin and amine metabolism reach maturity at different times during the perinatal period.

The effect of cigarette smoke on the metabolism of arachidonic acid in isolated hamster lungs

The effects of cigarette smoke on the metabolism of exogenous arachidonic acid (AA) were investigated in isolated hamster lungs. Arachidonate was injected into the pulmonary circulation and the metabolites were analysed from the nonrecirculating perfusion effluent by thin layer chromatography. After the pulmonary injection of 66 nmol of 14C-AA about 20% of the injected radioactivity appeared in the perfusion effluent mostly as metabolites in six minutes. When isolated lungs were ventilated with cigarette smoke during the perfusion, the amounts of PGF2 alpha, PGE2 and two unidentified metabolite groups increased in the lung effluent. In two other experimental series hamsters were exposed to cigarette smoke before the lung perfusion either once for 30 min or during one hour daily for ten consecutive days. Neither pre-exposures caused any changes in the amounts of arachidonate metabolites in the lung effluent.