Occupational exposure to urban stressors and effects on atrial natriuretic peptide: preliminary results

PURPOSE

The aim of this pilot study is to evaluate whether occupational exposure to low doses of pollutants present in the air of the city selected for the study could cause alterations in the concentration of atrial natriuretic peptide (ANP) in workers from the Municipal Police with outdoor tasks, compared to those with indoor tasks.

METHODS

A total of 208 non-smoking male and female subjects were enrolled and divided on the basis of whether their tasks were mainly outdoors or indoors. The dosage of plasma ANP was carried out on all workers included in the study. Differences between means and frequencies were compared using student's t-test for unpaired data and chi-square test with Yates' correction, and they were considered significant when the p value was <0.05.

RESULTS

Even after the subdivision of the total sample on the basis of sex, mean plasma levels of ANP were higher but not statistically significant in traffic police compared with controls.

CONCLUSIONS

The preliminary results suggest that further studies should be conducted before the influence of urban pollution on ANP could be confirmed or rejected.

Professional exposure to anaesthetic gases in health workers: estimate of some hepatic and renal tests

OBJECTIVES

The aim of this study is to estimate whether the occupational exposure to low dose of anaesthetic gases could cause alterations of haematochemical hepatic and renal parameters in the health workers of a city hospital.

MATERIALS AND METHODS

After excluding the main confounding factors, 154 exposed subjects and 98 not exposed controls were included in the study. The exposed subjects were divided in more exposed (group 1: n.54) and less exposed (group 2: n.100). Each worker included in this study underwent the CBC test (Complete Blood Count test). The differences between means were compared using the Student T test for unpaired data and considered significant when the p value was < 0.05.

RESULTS

The mean values of serum albumin, alpha 1, alpha 2, beta and gamma globulins were significantly decreased in health workers of both groups compared to controls. The mean values of serum creatinine and gamma-GT were significantly higher in health workers of group 2 compared to controls.

CONCLUSIONS

The obtained results suggest that occupational exposure to low dose of anaesthetic gases could influence haematochemical hepatic and renal parameters in exposed health workers.

Workers of the printing industry and hepatic damage

BACKGROUND

Typesetting industry is still the primary instrument of communication, despite the development of new technological systems. This study focuses on the analysis of the hepatic effects induced by the use of some organic solvents employed in the printing industry.

METHODS

We studied a group of 194 workers: 93 exposed and 101 not exposed. The level of the exposure to chemical pollutants were assessed through the environmental monitoring of blood concentrations and the analysis of airborne substances. The health survey was performed through the collection of the medical history and the use of hepatic tests, which were evaluated by calculating Mean, Standard Deviation, Student's t-test and X² test with Yates Correction, to investigate statistically significant differences in some hepatic parameters: AST, ALT, ALP, GGT, fractional and total bilirubin. The environmental data sometimes exceeded the TLV-TWA.

RESULTS

The clinical evaluation of the hepatic parameters showed statistically significant differences as to the hematic concentrations of AST, ALT, GGT.

CONCLUSIONS

The results we obtained support the hypothesis of a risk among the printing industrial workers attributable to the hepatotoxic solvents. This risk seems to be related to the use of a mixture of solvents, although at low doses, and the analysis of the results obtained confirms the validity of the investigation for the health screening protocol adopted in order to identify subjects and/or population at risk of hepatotoxicity.

Correlation between urinary nickel and testosterone plasma values in workers occupationally exposed to urban stressors

BACKGROUND

The purpose of this study is to assess whether occupational exposure to low doses of nickel (Ni) present in urban air can cause alterations in the concentration of plasma testosterone in workers of the Municipal Police of a large Italian city assigned to different types of outdoor tasks.

METHODS

359 male subjects were included in the study and divided on the basis of job, age, length of service and smoking habits. The dosage of the atmospheric Ni was performed by personal dosimetries on a sample of the workers included in the study. For each worker included in the study the dosage of whole blood Ni and of the plasma testosterone was carried out. The total sample was subjected to the independent-samples T-test and the Mann-Whitney U test for variables with 2 modes (smoking cigarette) and the ANOVA test and the Kruskal Wallis test for variables with more than 2 modes (age, length of service and job function). The correlation of Pearson with p at 2 wings between the variables was evaluated in the total sample and after subdivision on the basis of smoking and on the basis of the job. After taking into account the major confounding factors the multiple linear regression was performed on the total sample and after breakdown by tasks.

RESULTS

The correlation between the values of urinary Ni and the values of plasma testosterone on the total sample and for all classes of subdivision was found constantly negative. These results were confirmed by multiple linear regression, which indicated the Ni as the only significant variable that can contribute to the alterations of the testosterone.

CONCLUSIONS

Based on the results, the Authors suggest that occupational exposure to low doses of Ni present in the urban environment is able to influence some lines of the hypothalamic-pituitary-gonadal axis in exposed workers.

Perceived stress and stress-related parameters

BACKGROUND

The purpose of this study is to evaluate, using a questionnaire developed by our research group, whether occupational exposure to physical, chemical and psychosocial urban stressors can lead to alterations in perceived stress in a group of both male and female outdoor workers. The study also examines possible correlations between the levels of stress as inferred from the scores of the questionnaire and the levels of certain stress-related parameters (prolactin levels, consumption of coffee, chocolate, alcohol and cigarette smoking).

METHODS

We evaluated a final sample of 480 subjects (342 male and 138 female). All workers included in the study were divided into three groups on the basis of scores of the questionnaire.

RESULTS

About 60% of workers showed a moderate or severe stress condition, with a statistically significant prevalence of female workers and younger subjects. There was a statistically significant correlation between the questionnaire score and the mean levels of stress-related parameters. The increase of perceived stress increases significantly the mean levels of prolactin and the consumption of coffee, chocolate and cigarettes. There was no statistically significant differences for alcohol consumption.

CONCLUSIONS

The results show that exposure to chemical physical and psycho-social urban stressors can influence perceived stress in outdoor workers. The questionnaire used in our research could be an useful instruments for physicians during the health surveillance visits

Professional exposure to ionizing radiations in health workers and white blood cells

BACKGROUND

The aim of this study is to estimate if low dose of occupational exposure to ionizing radiations can cause alterations of plasma concentrations of total white blood cells, lymphocytes, monocytes and granulocytes (eosinophils, basophils, neutrophils), in the health workers of a big hospital.

METHODS

266 non smokers subjects of both sexes (133 health workers and 133 controls) were included in this study, compared on the basis of sex, age and working seniority. The complete blood count (CBC) was performed in all included workers.

RESULTS

The differences between the mean values were compared using Student T-test for unpaired data. The frequencies of the single variables were compared using Chi (2) test with Yates correction. The differences were considered significant when the P values were < 0.05. The mean values and the distribution of the mean values of total white blood cell were significantly decreased in health workers of both sexes compared to controls. The average values of granulocytes neutrophils were significantly low in female health workers compared to female controls.

CONCLUSIONS

The obtained results suggest that low dose of occupational exposure to ionizing radiations is able to influence some lines of the hematopoietic system in exposed workers.

Occupational exposure to traffic pollutants and peripheral blood counts

Aim of the study is to evaluate whether occupational exposure to low doses of pollutants present in the air of the city selected for the study could cause alterations in peripheral blood counts in workers of the Municipal Police with outdoor tasks vs workers with indoor tasks. 279 non smoker males were enrolled and divided on the basis of their different kind of task. The dosage of air pollutants was carried out through the use of personal air samplers on a representative group of workers. Data obtained were subject to statistical evaluation consisting of Homogeneity of variance test, ANOVA univariate test with post hoc Bonferroni correction, Jonckheere-Terpstra test and multiple linear regression analysis. The differences were considered statistically significant when p values were lower than 0.05. Mean levels of RBC, HB, MCHC, WBC and neutrophil cells were significantly higher in traffic policemen and police drivers compared to controls (workers with indoor tasks). Mean levels of MCV, MCH and lymphocytes were significantly lower in traffic policemen and police drivers compared to controls. These results were confirmed by Multiple linear regression test and Jonckheere-Terpstra test. The results suggest that prolonged occupational exposure to low doses of traffic pollutants can alter some lines of the hematopoietic system in exposed workers.

A comparison of coronary artery stenting with angioplasty for isolated stenosis of the proximal left anterior descending coronary artery: five year clinical follow up

BACKGROUND

Stent implantation for isolated stenosis of the proximal left anterior descending coronary artery (LAD) with preserved left ventricular function has been found to have a better clinical and angiographic outcome at one year than balloon angioplasty (PTCA).

OBJECTIVE

To establish whether those results are maintained at five year follow up.

METHODS

Patients were followed at least every six months. For those who died during follow up, data were obtained from medical records.

MAIN OUTCOME MEASURES

Freedom from death, non-fatal myocardial infarction, cerebrovascular accident, and repeated target lesion revascularisation. Secondary end points were revascularisation in a remote region and freedom from angina.

RESULTS

Follow up was complete in all patients. At five years, the primary end point was reached more often by patients randomised to stent implantation than to PTCA (80% v 53%; odds ratio (OR) 0.29 (95% confidence interval (CI) 0.13 to 0.69); p = 0.0034). In the PTCA group, 35% of patients underwent target lesion revascularisation v 15% in the stent group (OR 0.33, 95% CI 0.13 to 0.80; p = 0.014). There was a trend towards increased mortality in the PTCA group than in the stent group (17% v 7%; OR 0.36, 95% CI 0.10 to 1.21; p = 0.098). No significant differences were found between PTCA and stent groups for non-fatal myocardial infarction (8% v 5%; OR 0.58, 95% CI 0.13 to 2.54; p = 0.46) or cerebrovascular accident (2% v 0%).

CONCLUSIONS

In patients with isolated stenosis of the proximal LAD, a five year clinical follow up confirmed a better outcome in those treated with stenting than with PTCA.

The use over time of statins in coronary patients in an Italian tertiary referral center

BACKGROUND

In the last decade, large-scale clinical trials have consistently shown that therapy with statins is of great benefit to patients with and at risk of developing coronary artery disease. We assessed, in a sample of patients with coronary artery disease in whom coronary angiography was indicated and hospitalized in the last 10 years, the use of statins at admission.

METHODS

One hundred patients with stable coronary artery disease were randomly selected per year from 1991 to 2000. The final study population consisted of 1000 patients. The prescription of statins for > or = 6 months before hospital admission was determined from a hospital-wide clinical database.

RESULTS

From 1995, the prevalence of patients treated with statins at hospital admission progressively increased. In 1991, only 2% of patients were treated with statins before hospital admission while in the year 2000, 38% of patients were receiving this treatment. The mean prevalence of patients treated with statins before and after 1995 was 3 vs 22% (p < 0.0001) respectively. The distribution of the demographic and clinical parameters and the prevalence of conventional cardiovascular risk factors were similar in patients treated or not treated with statins.

CONCLUSIONS

After 1994, in coincidence with the publication of the results of clinical trials showing the benefit of statins in patients with coronary artery disease, the use of these drugs increased significantly. This finding suggests that the widespread diffusion of the results of the major clinical trials and of guidelines drawn up by medical associations have had a significant impact on statin prescription in patients with coronary artery disease. Nevertheless our data also indicate that, despite overwhelming evidence on the benefits of statin therapy, in current clinical practice cardiologists are not optimally utilizing lipid management and that statins are frequently prescribed without an appropriate analysis of risk factors.

Unstable angina and elevated c-reactive protein levels predict enhanced vasoreactivity of the culprit lesion

BACKGROUND

Because plaque inflammation may modulate coronary vasomotion, the association between systemic levels of C-reactive protein (CRP) and coronary vasoreactivity was assessed in patients with stable or unstable angina.

METHODS AND RESULTS

In 31 patients with stable angina and 23 patients with unstable angina undergoing coronary angiography, minimal luminal diameter (MLD) of the culprit lesion was measured by quantitative coronary angiography at baseline, during the cold pressor test (CPT), and after intracoronary administration of nitroglycerin (NTG) and expressed as percent change from baseline. MLD of patients with unstable angina exhibited a greater reduction during CPT and a greater increase after NTG than did patients with stable angina (-17+/-14% versus -5+/-12%, P=0.0013, and 34+/-25% versus 8+/-20%, P<0.001, respectively). According to preprocedural serum levels of CRP, 36 patients had normal (</=0.5 mg/dL) and 18 patients had elevated CRP levels. MLD of patients with elevated CRP levels exhibited a greater reduction during CPT and a greater increase after NTG than of patients with normal CRP levels (-15+/-12% versus -7+/-14%, P=0.037, and 31+/-23% versus 13+/-25%, P=0.011, respectively). Both unstable angina and elevated CRP levels resulted in independent predictors of enhanced vasoreactivity at the multivariate analysis.

CONCLUSIONS

This study confirms enhanced vasoreactivity of the culprit lesion in patients with unstable angina compared with those with stable angina. More importantly, it demonstrates that inflammatory mechanisms play a key role in modulating the reactivity of coronary atherosclerotic plaques and may partially account for the enhanced vasoreactivity of the unstable plaques.

Endothelial activation in patients with cardiac syndrome X

BACKGROUND

The presence of endothelial dysfunction with increased endothelin-1 plasma concentrations in patients with cardiac syndrome X is still under debate. The aim of the present study was to evaluate the presence of endothelial dysfunction in patients with cardiac syndrome X.

METHODS AND RESULTS

++Endothelin-1 levels were evaluated with a sensitive radioimmunoassay with previous purification through reverse phase HPLC in 24 patients (3 men and 21 women, mean age 54+/-7 years) with typical angina, instrumental evidence of ischemia, and normal coronary angiograms both under baseline conditions and after oral glucose load (75 g D-glucose). We also measured plasma nitrite-plus-nitrate levels, a sharp index of endothelial nitric oxide production, and circulating concentrations of the soluble fraction of the endothelial adhesion molecule vascular cell adhesion molecule-1, a well-recognized marker of early endothelial dysfunction. Fourteen healthy subjects (1 man and 13 women, mean age 47+/-15 years) served as controls. There were no significant differences in baseline plasma endothelin-1 concentrations between patients and control subjects (0.55+/-0.34 versus 0.48+/-0.22 pg/mL, P=0.503). Plasma nitrite-plus-nitrate and soluble vascular cell adhesion molecule-1 concentrations were also similar between the 2 groups. After glucose ingestion, circulating endothelin-1 concentrations were significantly higher in patients with cardiac syndrome X than in control subjects (P<0.03 at 60, 90, and 120 minutes).

CONCLUSIONS

Our findings show that no basal endothelial damage is present in patients with cardiac syndrome X. Nevertheless, increased responsiveness of endothelin-1 to glucose loading suggests that patients with cardiac syndrome X present an increased susceptibility to releasing endothelin-1 under stressful circumstances.

Ischemic preconditioning during coronary angioplasty is preserved in elderly patients

BACKGROUND

To establish whether the adaptation to ischemia observed in humans during percutaneous transluminal coronary angioplasty (PTCA) after repeated balloon inflations, i.e. a clinical correlate of ischemic preconditioning, is preserved in elderly patients.

METHODS

We studied 53 consecutive patients undergoing successful angioplasty for an isolated stenosis of a major epicardial coronary artery. On the basis of age, patients were separated into terciles: patients in the lower and middle terciles were grouped together (Group 1, adult patients, n = 24, mean age 50 +/- 6 years) and compared with those in the upper tercile (Group 2, elderly patients, n = 29, mean age 68 +/- 3 years). Intracoronary electrocardiogram was obtained at the end of the first two balloon inflations. Collateral recruitment during repeated balloon inflations was assessed by using an intracoronary Doppler guide wire (23 patients) or by using an intracoronary pressure guide wire (30 patients).

RESULTS

In Group 1, ST-segment changes during the second inflation were significantly less than those at the end of the first inflation (6 +/- 3 vs 13 +/- 5 mm, p < 0.001). Similarly, in Group 2, ST-segment changes during the second inflation were significantly less than those at the end of the first inflation (6 +/- 4 vs 13 +/- 6 mm, p < 0.001). In both groups, collateral recruitment did not change from the first inflation to the second inflation (p = 0.1).

CONCLUSIONS

Our study confirms that adaptation to ischemia during repeated balloon inflations in the setting of PTCA is independent of collateral recruitment and, therefore, is mainly due to ischemic preconditioning. More importantly, our study indicates that ischemic preconditioning is preserved in elderly patients.

Predictive value of C-reactive protein in patients with unstable angina pectoris undergoing coronary artery stent implantation

This study was aimed at establishing the relation between baseline C-reactive protein levels and 12-month outcome in patients with unstable angina successfully treated with coronary artery stent implantation. Our results suggest that in patients with unstable angina and 1-vessel coronary disease successfully treated with coronary artery stent implantation, normal baseline serum levels of C-reactive protein identify a subgroup of patients at low risk of cardiac events during follow-up.

Preinfarction angina and myocardial preconditioning

In the current era of pharmacologic and mechanical reperfusion therapy, several studies have consistently shown that patients with myocardial infarction preceded by angina have smaller infarcts and a better in-hospital outcome after thrombolytic therapy than patients without preinfarction angina. At least three mechanisms may explain these differences between infarctions that are preceded by angina and those that are not: coronary collaterals, reperfusion rate, and ischemic preconditioning. Collaterals alone do not seem to explain the beneficial effects of preinfarction angina, although it is difficult to completely rule out their role in the clinical setting. The possibility that preinfarction angina is not protective per se, but rather is a predictor of a more rapid coronary reperfusion is attractive; however, it should be addressed by further clinical studies. Finally, it is likely that the beneficial effects of preinfarction angina are related to ischemic preconditioning. Although a direct demonstration of this hypothesis is still lacking, clinical features of preinfarction angina, which is characterized by anginal attacks preceding acute myocardial infarction, are very similar to those of ischemic preconditioning, in which brief ischemic episodes precede a prolonged ischemic period. Indeed, the demonstration of ischemic preconditioning in different clinical models of ischemia and reperfusion and the identification of some of its mediators suggest that in patients at high risk of myocardial infarction drugs known to block this endogenous form of protection should be used with caution, while drugs known to elicit preconditioning might have a relevant therapeutic role. However, the optimal timing, administration, and dosage for preconditioning-mimetic drugs in the appropriate clinical setting are still under debate and warrant further investigation.

Coronary flow reserve early and late after minimally invasive coronary artery bypass grafting in patients with totally occluded left anterior descending coronary artery

BACKGROUND

The impairment of flow reserve of the left anterior descending coronary artery in the early postoperative period in patients receiving a left internal thoracic artery graft has been related to the effects of cardiopulmonary bypass. Indeed, the late improvement in flow has been attributed to a late increase in left internal thoracic artery diameter.

METHODS

We evaluated 12 patients who underwent minimally invasive direct coronary artery bypass surgery with the internal thoracic artery used to graft an occluded left anterior descending artery without extracorporeal circulation. Early and 6 months after the operation, patients underwent a second angiogram of the left internal thoracic artery graft and assessment of coronary flow reserve by use of an intracoronary 0.014-inch Doppler guide wire.

RESULTS

At the late study, coronary flow reserve had increased compared with the early postoperative data from 1.8 +/- 0.4 (standard deviation) to 2.5 +/- 0.6 (P =.002) because of a significant decrease in baseline averaged peak velocity (32.4 +/- 6.2 vs 21.3 +/- 6.4 cm/s, P =.002), whereas the hyperemic values were similar (51 +/- 6 vs 53.7 +/- 21.9 cm/s, P =.6). The diameters of the thoracic artery (2.1 +/- 0.3 vs 2.2 +/- 0.3 mm, P =. 7) and the left anterior descending coronary artery (1.8 +/- 0.1 vs 1.8 +/- 0.2 mm, P =.5), as well as myocardial oxygen consumption (106 +/- 14 vs 101 +/- 16 mm Hg. beats/min. 10(-2), P =.5), were unchanged.

CONCLUSIONS

Our findings suggest that the late improvement in coronary flow reserve is independent of the diameter of the graft and probably reflects an early distal coronary vessel dysfunction, which normalizes with time.

Ischemic preconditioning in humans: models, mediators, and clinical relevance

Ischemic preconditioning, a powerful form of endogenous protection against myocardial infarction, has been demonstrated in several animal species and, recently, in isolated human cardiomyocytes. For both logistic and ethical reasons, no clinical study can meet the strict conditions of experimental studies on preconditioning with infarct size as the end-point. Nevertheless, the demonstration of adaptation to ischemia observed during in vitro studies on human atrial trabeculae, in patients in the setting of coronary bypass surgery, and in the setting of coronary angioplasty in the absence of collateral vessel recruitment strongly suggests that ischemic preconditioning occurs in humans. This notion is further supported by the observation that in these human models, the adaptation to ischemia is influenced by drugs acting on K(ATP) channels and on purinergic and alpha-adrenergic receptors, similar to what is observed in accepted experimental models of ischemic preconditioning. This important form of myocardial endogenous protection may also play a role in the warm-up phenomenon and in mediating the beneficial effects of preinfarction angina. The demonstration of ischemic preconditioning in humans and the identification of some of its mediators suggests that in patients at high risk for myocardial infarction, drugs known to block this endogenous form of protection should be used with caution, whereas drugs known to elicit preconditioning might have a relevant therapeutic role.

Coronary artery stent placement in patients with variant angina refractory to medical treatment

We performed a prospective study to establish the efficacy of coronary stent placement in a highly selected group of patients with focal coronary artery spasm in whom anginal attacks could not be prevented by full medical therapy. The results of this study indicate that intracoronary stent placement may represent an alternative and feasible treatment for patients with vasospastic angina refractory to aggressive medical therapy.

Exercise-induced myocardial ischemia triggers the early phase of preconditioning but not the late phase

The aim of the present study was to establish whether exercise-induced ischemia triggers the second window of protection in 15 patients with coronary artery disease undergoing 2 consecutive treadmill exercise tests and a third test 24 hours later. Our findings confirm that a first exercise-induced ischemic challenge induces the early phase of preconditioning but not the late phase, thus suggesting that either a late protective effect of preconditioning does not exist in the setting of demand ischemia or, if it exists, it must be weaker than the early protective effect.

Effects of K(ATP) channel blockade by glibenclamide on the warm-up phenomenon

AIMS

The increased tolerance to myocardial ischaemia observed during the second of two sequential exercise tests, i.e. the warm-up phenomenon, has been proposed as a clinical model of ischaemic preconditioning. As ATP-sensitive K+ channels appear to be a mediator of ischaemic preconditioning in both experimental and clinical studies, the aim of this study was to investigate the role of K(ATP) channels in the warm-up phenomenon.

METHODS AND RESULTS

Twenty-six patients with coronary artery disease were randomized to receive 10 mg oral glibenclamide, a selective ATP-sensitive K+ channel blocker, or placebo. Sixty minutes after glibenclamide or placebo administration, patients were given an infusion of 10% dextrose (8 ml x min(-1)) to correct glucose plasma levels or, respectively, an infusion of saline at the same infusion rate. Thirty minutes after the beginning of the infusions, both patient groups underwent two consecutive treadmill exercise tests, with a recovery period of 15 min to re-establish baseline conditions. Before exercise tests, blood glucose levels were similar in placebo and glibenclamide groups (96 +/- 10 vs 105 +/- 22 mg x 100 ml(-1), P=ns). After placebo administration, rate-pressure product at 1.5 mm ST-segment depression significantly increased during the second exercise test compared to the first (220 +/- 41 vs 186 +/- 29 beats x min(-1) x mmHg x 10(2), P<0.01), but it did not change after glibenclamide (191 +/- 34 vs 187 +/- 42 beats x min(-1) x mmHg x 10(2), P=ns), with a significant drug-test interaction (P=0.0091, at two-way ANOVA).

CONCLUSIONS

Glibenclamide, at a dose previously shown to abolish ischaemic preconditioning during coronary angioplasty, prevents the increase of ischaemic threshold observed during the second of two sequential exercise tests. These findings confirm that ischaemic preconditioning plays a key role in the warm-up phenomenon and that in this setting is, at least partially, mediated by activation of ATP-sensitive K+ channels.

Predictive value of C-reactive protein after successful coronary-artery stenting in patients with stable angina

Plasma levels of C-reactive protein were measured 72 hours after successful coronary artery stenting in 76 patients with stable angina pectoris. At 12-month follow-up, the cumulative event rate was higher in patients with abnormal levels of C-reactive protein than that observed in patients with normal C-reactive protein who were event free.

Phentolamine prevents adaptation to ischemia during coronary angioplasty: role of alpha-adrenergic receptors in ischemic preconditioning

BACKGROUND

Experimental studies indicate that alpha-adrenergic receptors are involved in ischemic preconditioning. Their role in humans is unknown.

METHODS AND RESULTS

Eighteen patients undergoing angioplasty for an isolated stenosis of the left anterior descending coronary artery were randomized to receive intravenous infusion of phentolamine or placebo during the procedure. Intracoronary ECG and cardiac pain were determined at the end of the first two balloon inflations. Average peak velocity in the contralateral coronary artery during balloon occlusion, an index of collateral recruitment, was also assessed by using a Doppler guide wire. In both phentolamine- and placebo-treated patients, average peak velocity significantly increased from baseline to the end of the first inflation (P<.01), but it did not show any further increase during the second inflation. In phentolamine-treated patients, ST-segment changes and cardiac pain severity during the second inflation were similar to those observed during the first inflation (13+/-9 versus 12+/-8 mm, P=NS, and 51+/-34 versus 54+/-32 mm, P=NS, respectively), whereas in placebo-treated patients, they were significantly less (6+/-4 versus 13+/-7 mm, P<.01, and 26+/-20 versus 49+/-22 mm, P<.05, respectively).

CONCLUSIONS

The adaptation to ischemia observed in humans after two sequential coronary balloon inflations is abolished by phentolamine and is independent of collateral recruitment. Thus, it occurs due to ischemic preconditioning and is, at least in part, mediated by alpha-adrenergic receptors.

Stent implantation for spontaneous coronary dissection

Spontaneous coronary artery dissection is a rare cause of acute myocardial infarction and sudden death. We report a case of diffuse spontaneous left coronary artery dissection occurring in the postpartum period, successfully treated by multiple stent implantation. Coronary angiography performed 3 months later showed no evidence of dissection and TIMI flow grade 3 in the treated coronary arteries. At 12-month follow-up the patient was asymptomatic.

Effects of A1 adenosine receptor blockade on the warm-up phenomenon

The increased tolerance to myocardial ischemia observed during the second of two sequential exercise tests, i.e. the warm-up phenomenon, has been proposed as a clinical model of ischemic preconditioning. Adenosine appears to be a mediator of ischemic preconditioning in both experimental and clinical settings. The purpose of this study was to investigate the role of A1 adenosine receptors in the warm-up phenomenon. A double-blind, placebo-controlled, cross-over design was used. Twelve patients with coronary artery disease and positive exercise test were randomized to receive either bamiphylline, a selective A1 adenosine receptor antagonist, or placebo, immediately prior to two consecutive treadmill exercise tests carried out on day 1. Then, on day 2 all patients underwent two consecutive exercise tests immediately after administration of the remaining treatment. During the first exercise test, bamiphylline, compared to placebo, increased the time to and rate-pressure product at 1.5 mm ST-segment depression (from 317 +/- 118 to 423 +/- 127 s, p < 0.05 and from 199 +/- 38 to 230 +/- 36 b/min.mmHg.10(2), p < 0.05, respectively). After both placebo and bamiphylline infusions, time to 1.5 mm ST-segment depression during the second exercise test was greater than that during the first test (445 +/- 121 vs 317 +/- 118 s, p < 0.001 and 483 +/- 128 vs 423 +/- 127 s, p < 0.05, respectively), as was rate-pressure product at 1.5 mm ST-segment depression (228 +/- 40 vs 199 +/- 38 b/min.mmHg.10(2), p < 0.01 and 253 +/- 42 vs 230 +/- 36 b/min.mmHg.10(2), p < 0.05, respectively). In conclusion, bamiphylline, at a dose able to increase ischemic threshold and exercise tolerance compared to placebo, does not prevent the warm-up phenomenon. These findings suggest that, in the setting of the warm-up phenomenon, A1 adenosine receptor blockade is insufficient to prevent ischemic preconditioning.

A comparison of coronary-artery stenting with angioplasty for isolated stenosis of the proximal left anterior descending coronary artery

BACKGROUND

Randomized studies have shown that the use of coronary-artery stenting as the initial treatment for coronary stenosis is associated with a lower risk of restenosis than is standard coronary angioplasty. We prospectively investigated the efficacy of these two approaches in selected patients with isolated stenosis of the proximal left anterior descending coronary artery.

METHODS

A total of 120 patients with isolated stenosis of the proximal left anterior descending coronary artery were randomly assigned to stent implantation or standard coronary angioplasty. The primary clinical end points were the rate of procedural success (defined as residual stenosis of less than 50 percent and the absence of death, myocardial infarction, and the need for coronary-artery bypass surgery during the hospital stay) and the rate of event-free survival (defined as freedom from death, myocardial infarction, and the recurrence of angina) at 12 months. The angiographic end point was the rate of restenosis 12 months after the procedure.

RESULTS

The two treatment groups did not differ significantly with respect to demographic, clinical, or angiographic characteristics. The rates of procedural success were similar in the two groups of patients (95 percent in the stenting group vs. 93 percent in the angioplasty group, P = 0.98). The 12-month rates of event-free survival were 87 percent after stenting and 70 percent after angioplasty (P = 0.04). The rates of restenosis were 19 percent after stent implantation and 40 percent after angioplasty (P = 0.02).

CONCLUSIONS

In patients with symptomatic isolated stenosis of the proximal left anterior descending coronary artery, stenting had advantages over standard coronary angioplasty in that it was associated with both a lower rate of restenosis and a better clinical outcome.

Effects of bamiphylline on exercise testing in patients with syndrome X

An abnormal stimulation of adenosine A1-receptors has been suggested to play a role in the pathogenesis of both chest pain and ischemia-like electrocardiographic changes in patients with syndrome X and a nonselective adenosine antagonist (theophylline) has been reported to be beneficial in these patients. In this study we investigated the acute effects of bamiphylline, a specific A1-receptor antagonist, in 16 patients with syndrome X (14 women, age 57 +/- 6 years), with both angina and ST-segment depression inducible during exercise testing. All patients underwent two treadmill exercise tests (Bruce modified protocol) on 2 separate days, 5 minutes after the end of randomized intravenous infusion of either placebo (saline solution) or bamiphylline (300 mg). Severity of chest pain was assessed by a 100 mm visual analogic scale. There were no significant differences in resting heart rate and blood pressure after bamiphylline or placebo. Rate-pressure product (20 600 +/- 5000 vs 20 200 +/- 5200 bpm.mmHg), time to 1 mm ST depression (549 +/- 196 vs 581 +/- 201 sec), time to angina (519 +/- 209 vs 571 +/- 196 sec), and exercise duration (717 +/- 134 vs 676 +/- 166 sec) were also not significantly different after bamiphylline or placebo, but there was a mild reduction of the severity of exercise-induced chest pain (30 +/- 22 vs 39 +/- 20 mm, p < 0.05) with the active drug. Thus, in patients with syndrome X, bamiphylline does not improve exercise-induced ST changes, suggesting that A1-receptors are not significantly involved in their appearance. In addition, bamiphylline had little effect on anginal pain, suggesting that this cannot be mediated exclusively by A1-receptor stimulation in these patients.

Differences of regional coronary flow reserve assessed by adenosine thallium-201 scintigraphy early and six months after successful percutaneous transluminal coronary angioplasty or stent implantation

This study assesses regional coronary flow reserve using adenosine thallium-201 scintigraphy early and 6 months after angiographically successful percutaneous transluminal coronary angioplasty (PTCA) or stent implantation. Seventeen consecutive men with a significant isolated left anterior descending coronary artery stenosis were scheduled for repeat coronary angiography and adenosine-planar thallium-201 scintigraphy within 24 hours and 6 months after successful PTCA (n = 8) or stent implantation (n = 9). After background subtraction, left ventricular segmental uptake was semiquantitatively assessed on thallium images. The perfusion defect severity was scored from 0 (normal) to 3. Coronary angiograms were analyzed using an automated edge contour detection computer analysis system. Data are expressed as mean value +/- 1 SD, and proportions as percentage. The residual narrowing was 17 +/- 8% after PTCA and 9 +/- 2% after stent implantation (p = 0.02). Twenty-four hours after the procedure, hypoperfused segments were detected in all patients (100%) and in 4 patients (44%) (p = 0.05), respectively. The total number of hypoperfused segments was greater after PTCA than after stent implantation (16 [40%] vs 7 [16%], p = 0.001, respectively) as was the perfusion defect severity (4.4 +/- 3.1 vs 1 +/- 1.2, p = 0.006). Six months after the procedure, 3 of the 5 patients who had undergone PTCA without restenosis still had reversible perfusion defects. None of the stent-treated patients had restenosis or reversible perfusion defects (p = 0.05). Among PTCA-treated patients without restenosis, the total number of hypoperfused segments and the perfusion defect severity were 9 of 25 (36%) and 0.8 +/- 0.8, respectively. Thus, a regional reduction in coronary flow reserve, occasionally observed early after successful stent implantation, is probably due to a transient alteration of small coronary vessels, as was also supported by the absence of perfusion defects 6 months after the procedure. The more severe impairment of regional coronary flow reserve observed early after successful PTCA is probably also due to angiographic underestimation of the residual stenosis, as suggested also by the persistence of reversible perfusion defects 6 months after the procedure in a few patients.

Mechanisms of the warm-up phenomenon

The warm-up phenomenon, described in patients with coronary artery disease, refers to the improved performance following a first exercise test. The aim of this study was to investigate the causes of the warm-up phenomenon. Fifteen patients with coronary artery disease and positive exercise test were enrolled. Patients were off treatment throughout the study. They underwent two consecutive treadmill exercise tests according to the Bruce protocol, with a recovery period of 10 min to re-establish baseline conditions. A third exercise test was then performed 2 h later. Before the onset of ischaemia, the rate-pressure product for a similar degree of workload was similar during the first and second exercise test, while it was lower during the third test (P < 0.05). Time to 1.5 mm ST-segment depression during the second and third exercise test was greater than during the first test (454 +/- 133 and 410 +/- 161 vs 354 +/- 127 s, P < 0.01, respectively). Similarly, the time to anginal pain onset was increased during the second and third exercise tests, compared to the first test (356 +/- 208 and 310 +/- 203 vs 257 +/- 204 s, P < 0.01, respectively). In contrast, rate-pressure product at 1.5 mm ST-segment depression during the second test was higher than that during the first test (232 +/- 47 vs 210 +/- 39 beats.min-1.mmHg.10(2), P < 0.01), while in the third test it was similar to that during the first (209 +/- 43 beats.min-1.mmHg.10(2), P = ns). The warm-up phenomenon observed a few minutes after exercise is characterized by an increase of both time to ischaemia and ischaemic threshold; this adaptation to ischaemia may be due to an improvement of myocardial perfusion or to preconditioning. Conversely, the warm-up phenomenon observed a few hours after repeated exercise is characterized by an increase of time to ischaemia but not of ischaemic threshold and is caused by a slower increase of cardiac workload. Thus, the mechanisms of the warm-up phenomenon may be different, time dependent and related to previous training.

Effects of A1 adenosine receptor blockade by bamiphylline on ischaemic preconditioning during coronary angioplasty

OBJECTIVE

The role of A1 adenosine receptors in preconditioning in humans is unknown. To establish whether bamiphylline, a selective antagonist of A1 adenosine receptors, abolishes ischaemic preconditioning in man, 36 consecutive patients undergoing single-vessel coronary angioplasty were randomized to receive intravenous infusion of bamiphylline (5 mg.kg-1) or placebo (0.9% NaCl) immediately prior to the procedure.

DESIGN

The mean values (+/- 1 SD) of ST segment shifts on the surface and intracoronary electrocardiograms were measured at the end of the first and second balloon inflations, both 2 min long. The severity of cardiac pain was obtained at the same time using a visual analogue scale.

RESULTS

In bamiphylline-treated patients, the mean ST segment shift and the severity of cardiac pain during the second inflation were similar to those during the first inflation (14 +/- 15 vs 16 +/- 16 mm, ns and 31 +/- 28 vs 31 +/- 29, ns, respectively). Conversely, in placebo-treated patients both the mean ST segment shift and the severity of cardiac pain during the second inflation were significantly less than those during the first inflation (10 +/- 6 vs 17 +/- 7 mm, P < 0.001 and 25 +/- 21 vs 39 +/- 31 mm, P < 0.01, respectively). Thus, bamiphylline abolishes ischaemic preconditioning observed in man during repeated coronary balloon inflations.

CONCLUSION

These results suggest that, in this setting, ischaemic preconditioning is mediated, at least in part, by A1 adenosine receptors.

Early postoperative myocardial ischemia after coronary artery bypass grafting. Detrimental effects of nitroglycerine infusion

This study was aimed at assessing the incidence and mechanisms of myocardial ischemia early after coronary artery bypass grafting and the effects of treatment with nitroglycerine. The electrocardiogram of 35 patients (29 males and 6 females, mean age 61 +/- 8 years) with stable angina and multivessel coronary disease, was monitored continuously for 24 hours after uncomplicated coronary artery bypass grafting. Patients were randomized to receive nitroglycerin infusion or placebo. Fourteen of the 35 patients (40%) had 24 transient ischemic episodes (mean duration 11.8 +/- 3.5 min; range 6-20 min with ST segment elevation in 6, ST segment depression in 7 and both ST segment elevation and depression in 1. Seventy-five per cent of the ischemic episodes occurred within the first 6 postoperative hours. The mean ejection fraction prior to surgery and the mean number of stenosed vessels and of the implanted grafts were similar in patients with and without postoperative ischemia (57 +/- 5 vs 57 +/- 6%, p = 0.86; 2.7 +/- 0.5 vs 2.8 +/- 0.4, p = 0.52 and 3.0 +/- 0.9 vs 3.2 +/- 0.7, p = 0.51, respectively) as well as total bypass time and cross-clamp time (123 +/- 38 vs 124 +/- 18 min, p = 0.89 and 67 +/- 20 vs 70 +/- 14 min, p = 0.68, respectively). The values of heart rate and systolic blood pressure at the onset of the ischemic episodes were similar to those recorded 15 min before (103 +/- 16 vs 106 +/- 18 b/min, p = 0.36 and 119 +/- 12 vs 121 +/- 14 mmHg, p = 0.48). Ischemic episodes were recorded in 9 of the 16 patients (56%) randomized to receive nitroglycerine and in 5 only of the 19 patients (26%) randomized to receive placebo (p = 0.05). Thus, transient ischemic episodes occurring early after coronary artery bypass grafting are not preceded by an increase in myocardial oxygen consumption; they appear to be due, therefore, to a primary reduction in coronary blood flow. Treatment with nitroglycerine is associated with a higher prevalence of ischemic episodes, thus suggesting that myocardial ischemia is unlikely to be caused by spasm of large epicardial vessels or grafts. Myocardial ischemia may be caused, instead, by extracorporeal circulation-induced alterations enhanced by the hypotensive effects of nitroglycerine.

Risk factors in patients with different clinical and angiographic manifestations of ischemic heart disease

In patients who present with unheralded myocardial infarction both the severity and the extent of coronary atherosclerosis appear to be less than that in patients with chronic stable angina, thus suggesting that, in the latter, protective factors may prevent or delay the evolution towards acute coronary syndromes. Therefore, risk factors were compared in 88 consecutive patients (73 men; mean age 56 +/- 9 years) with unheralded myocardial infarction and a single, discrete, > 70% stenosis in the proximal right, left circumflex or left anterior descending coronary artery (Group 1) and in 55 consecutive patients (46 men; mean age 58 +/- 9 years with chronic stable angina and multiple, diffuse, > 70% stenoses localized both in the right and left coronary arteries (Group 2). Continuous data are presented as mean value +/- 1 SD, proportions as percentages. In Group 1 mean serum levels of total cholesterol, low-density lipoprotein cholesterol and triglycerides were similar to those in mg/dl, p = 0.93 and 160 +/- 87 vs 155 +/- 76, p = 0.74, respectively) while the mean serum level of high-density lipoprotein cholesterol was higher in Group 2 (49 +/- 4 vs 46 +/- 4 mg/dl, p = 0.005). The prevalence of a positive family history of ischemic heart disease, hypertension and smoking habit were similar in the two groups, while the prevalence of diabetes mellitus was higher in Group 2 (29 vs 6%, p = 0.001). Thus, in patients with otherwise similar coronary risk factors, higher levels of high-density lipoprotein cholesterol and diabetes mellitus appear to be associated with a reduced tendency of coronary atherosclerosis to cause acute coronary syndromes.

Muscular and cardiac adenosine-induced pain is mediated by A1 receptors

OBJECTIVES

This study attempted to establish whether bamiphylline, a selective antagonist of A1 adenosine receptors, prevents the algogenic effects of adenosine in humans.

BACKGROUND

Experimental findings indicate that the sympathoexcitatory response elicited by adenosine is mediated by A1 receptors.

METHODS

An intrailiac infusion of increasing doses (from 125 to 2,000 micrograms/min) of adenosine was given to 20 patients. Adenosine infusion was then repeated after intrailiac infusion of either bamiphylline or saline solution. In 14 other patients with angina, increasing doses of adenosine (from 108 to 1,728 micrograms/min) were infused into the left coronary artery. Adenosine infusion was then repeated after the intravenous infusion of either bamiphylline or placebo. Coronary blood flow velocity was monitored by a Doppler catheter. Data relative to pain severity are expressed as median and all other data as mean value +/- 1 SD.

RESULTS

Bamiphylline prolonged the time to pain onset caused by the intrailiac adenosine infusion from 444 +/- 96 to 749 +/- 120 s (p < 0.001) and reduced pain severity from 45 to 24 mm (p < 0.01). After placebo infusion, the time to pain onset and pain severity were similar to that of baseline (428 +/- 112 vs. 430 +/- 104 s, p = 0.87 and 44 vs. 43 mm, p = 0.67, respectively). Bamiphylline prolonged the time to pain onset caused by intracoronary adenosine infusion from 519 +/- 128 to 603 +/- 146 s (p < 0.01) and reduced pain severity from 58 to 28 mm (p < 0.02). After placebo infusion, the time to pain onset and pain severity were similar to that at baseline (542 +/- 87 vs. 551 +/- 79 s, p = 0.14 and 55 vs. 50 mm, p = 0.61). Maximal coronary blood flow velocities before and after bamiphylline administration were similar (47 +/- 22 vs. 49 +/- 24 cm/s, p = 0.36) as well as before and after placebo administrtion (40 +/- 20 vs. 41 +/- 20 cm/s, p = 0.07).

CONCLUSIONS

Bamiphylline reduces adenosine-induced muscular and cardiac pain but does not affect adenosine-induced coronary vasodilation. These findings indicate that at the dose used in this study, bamiphylline does not detectably block vascular A2-receptor-mediated adenosine effects in humans, which suggests that the muscular and cardiac algogenic effects of adenosine are mediated mainly by A1 receptors.

Determinants of myocardial ischemia during percutaneous transluminal coronary angioplasty in patients with significant narrowing of a single coronary artery and stable or unstable angina pectoris

Previous studies have assessed the determinants of collateral vessel recruitment during coronary occlusion in patients undergoing percutaneous transluminal coronary angioplasty (PTCA). However, the determinants of severity of myocardial ischemia after sudden coronary occlusion do not necessarily coincide with those responsible for collateral vessel recruitment. The aim of this study was to assess the determinants of severity of myocardial ischemia during balloon inflation by recording surface and intra-coronary electrocardiograms (ECGs). In 62 consecutive patients with 1-vessel disease and without previous myocardial infarction undergoing successful PTCA for stable (n = 33) or unstable (n = 29) angina pectoris, the summation of the absolute values of ST-segment shifts from baseline on the intracoronary and surface ECG at the end of the first 2-minute inflation was obtained as an index of the severity of myocardial ischemia. Stenosis severity before PTCA was measured using computerized coronary angiography, while the grade of collateral filling was scored according to Rentrop's classification. The mean (+/- 1 SD) ST-segment shift at the end of balloon inflation was less in patients with than without collateral vessels (12 +/- 10 vs 23 +/- 15 mm, p < 0.05). Despite a similar prevalence of collateral vessels (34% vs 24%, p = NS), the mean ST-segment shift was also less in patients with unstable than stable angina (15 +/- 9 vs 24 +/- 17 mm, p < 0.05). However, the mean ST-segment shift was not associated with the severity of coronary stenosis before PTCA (r = 0.0004, p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Substance P potentiates the algogenic effects of intraarterial infusion of adenosine

OBJECTIVES

This study investigated whether substance P potentiates the muscular and cardiac pain caused by the intraarterial infusion of adenosine, an autocoid known to induce muscular and cardiac ischemic-like pain in humans.

BACKGROUND

Substance P is involved in the generation of neurogenic inflammation and causes cutaneous hyperalgesia. Because substance P is present in perivascular nerves it might also cause muscular and cardiac hyperalgesia. To test this hypothesis its effects on adenosine-induced muscular and cardiac pain were investigated in humans.

METHODS

A randomized, crossover study of the algogenic effects of the intrailiac infusion of increasing scalar doses (from 125 to 2,000 micrograms/min) of adenosine or substance P (11.2 pmol/min) for 3 min, followed by the simultaneous infusion of substance P plus the same doses of adenosine, was carried out in nine patients with no evidence of peripheral vascular disease. A similar protocol was carried out by infusing increasing scalar doses of adenosine (from 50 to 800 micrograms/min) or substance P (11.2 pmol/min) for 3 min, followed by the simultaneous infusion of substance P plus the same doses of adenosine, into the left coronary artery of eight patients with angina. Pain severity, assessed by a visual analog scale, is presented as median. The remaining data are presented as mean value +/- 1 SD.

RESULTS

All patients experienced pain during both adenosine and substance P plus adenosine infusion; no patient experienced pain during the infusion of substance P alone. During intrailiac infusion, all patients experienced pain in the right leg that occurred earlier (207 +/- 152 vs. 321 +/- 154 s, p < 0.05) and was greater (47 vs. 30 mm, p < 0.05) during the simultaneous infusion of substance P plus adenosine than during the infusion of adenosine. Similarly, during intracoronary infusion, all patients experienced chest pain that occurred earlier (409 +/- 242 vs. 596 +/- 210 s, p < 0.05) and was greater (51 vs. 33 mm, p < 0.05) during the simultaneous infusion of substance P plus adenosine than during infusion of adenosine. No patient exhibited electrocardiographic signs of ischemia.

CONCLUSIONS

Substance P does not cause muscular or cardiac pain, but it provokes muscular and cardiac hyperalgesia.

Ischemic preconditioning during coronary angioplasty is prevented by glibenclamide, a selective ATP-sensitive K+ channel blocker

BACKGROUND

Brief episodes of ischemia render the heart more resistant to subsequent ischemia; this phenomenon has been called ischemic preconditioning. In some animal species, myocardial preconditioning appears to be due to activation of ATP-sensitive K+ (KATP) channels. The role played by KATP channels in preconditioning in humans remains unknown. The aim of this study was to establish whether glibenclamide, a selective KATP channel blocker, abolishes the ischemic preconditioning observed in humans during coronary angioplasty following repeated balloon inflations.

METHODS AND RESULTS

Twenty consecutive patients undergoing one-vessel coronary angioplasty were randomized to receive 10 mg oral glibenclamide or placebo. Sixty minutes after glibenclamide or placebo administration, patients were given an infusion of 10% dextrose (8 mL/min) to correct glucose plasma levels or, respectively, an infusion of saline at the same infusion rate. Thirty minutes after the beginning of the infusion, both patient groups underwent coronary angioplasty. The mean values (+/- 1 SD) of ST-segment shifts on the surface 12-lead ECG and the intracoronary ECG were measured at the end of the first and second balloon inflations, both 2 minutes long. In glibenclamide-treated patients, the mean ST-segment shift during the second balloon inflation was similar to that observed during the first inflation (23 +/- 13 versus 20 +/- 8 mm, P = NS), and the severity of cardiac pain was greater (55 +/- 21 versus 43 +/- 23 mm on a scale of 0 to 100, P < .05). Conversely, in placebo-treated patients the mean ST-segment shift during the second inflation was less than that during the first inflation (9 +/- 5 versus 23 +/- 13 mm, P < .001), as was the severity of cardiac pain (15 +/- 15 versus 42 +/- 19 mm, P < .01). Blood glucose levels were significantly reduced 60 minutes after glibenclamide compared with those at baseline (53 +/- 9 versus 102 +/- 10 mg/100 mL, P < .001) in the glibenclamide group; however, before coronary angioplasty, blood glucose levels increased to 95 +/- 19 mg/100 mL, a value similar to that found in placebo group (96 +/- 11 mg/100 mL, P = NS).

CONCLUSIONS

In humans, ischemic preconditioning during brief repeated coronary occlusions is completely abolished by pretreatment with glibenclamide, thus suggesting that it is mainly mediated by KATP channels.

Evidence of cardiac suction in the presence of high end-diastolic filling pressure: a case report

Cardiac suction has been previously demonstrated in the normal heart and in cardiac diseases characterized by a normal or reduced end-diastolic ventricular pressure. We report a patient with tight mitral stenosis and severe tricuspid regurgitation who provides the evidence of cardiac suction, despite the presence of increased end-diastolic pressures. The negative diastolic pressures observed in our patient appear to be related to the preservation of a vigorous contraction of both ventricles resulting in small end-systolic volumes. In this setting the elastic potential energy stored in the myocardium during each vigorous contraction is released during diastole, thus creating a negative pressure which sucks blood into the ventricles.

Mechanisms of cardiac pain during coronary angioplasty

OBJECTIVES

This study was conducted to establish whether the cardiac pain patients experience during coronary angioplasty is modulated by 1) the stretching of the coronary artery wall, and 2) the mechanisms responsible for the ischemic preconditioning.

BACKGROUND

Anecdotal experimental observations indicate that stretching of the coronary artery wall is a stimulus adequate to cause cardiac pain. Furthermore, recent experimental studies indicate that adenosine, a mediator of the anginal pain, appears to play an important role in the genesis of ischemic preconditioning.

METHODS

We randomly allocated 48 consecutive patients undergoing coronary angioplasty into two groups. In Group A the second balloon inflation was performed at a higher level than the first; in Group B the first two inflations were performed at the same level of balloon pressure. The mean values (+/- 1 SD) of ST segment shift on the surface 12-lead electrocardiogram (ECG) and the intracoronary ECG were measured at the end of each inflation period. Severity of cardiac pain was also obtained at the same time by using a visual analog scale.

RESULTS

The mean ST segment shift during the second balloon inflation was significantly less than that during the first inflation in both groups of patients (12.8 +/- 9.3 vs. 18.5 +/- 11.9 mm, p < 0.001 and 13.7 +/- 10.1 vs. 21.3 +/- 13.9 mm, p < 0.001, respectively, in Groups A and B). Yet, the severity of cardiac pain during the second inflation was greater than that during the first inflation in Group A (40.8 +/- 32.7 vs. 26.9 +/- 27.2 mm, p < 0.01), whereas it was lesser in Group B (23.1 +/- 20.7 vs. 32.9 +/- 29.6 mm, p < 0.05). However, in the latter group, pain severity after normalization for the mean ST segment shift was similar during the first and second inflations (2.1 +/- 2.4 vs. 2.7 +/- 3.6, p = NS).

CONCLUSIONS

During coronary angioplasty, the cardiac pain experienced by patients is caused in part by stretching of the coronary artery wall. If the stretching is maintained at a constant level during repeated coronary occlusions, the cardiac pain is entirely predicted by the severity of myocardial ischemia and therefore does not appear to be directly modulated by the mechanisms responsible for the ischemic preconditioning.

Left ventricular volumes during exercise in normal subjects and patients with dilated cardiomyopathy assessed by first-pass radionuclide angiography

During isotonic exercise, left ventricular (LV) suction and the Frank-Starling law of the heart may have important roles in the enhancement of early LV diastolic filling and in the increase of myocardial contractility, respectively. It remains controversial whether these mechanisms operate in normal subjects or patients with dilated cardiomyopathy. Ten healthy subjects and 10 patients with idiopathic dilated cardiomyopathy who underwent maximal upright bicycle exercise testing were studied. First-pass radionuclide angiography was performed at both rest and peak exercise using a multicrystal gamma camera. In normal subjects, LV end-systolic volume at peak exercise was smaller than during baseline (17 +/- 7 vs 30 +/- 15 ml/m2; p < 0.05), whereas rapid filling volume was greater (52 +/- 16 vs 38 +/- 8 ml/m2; p < 0.01). In patients with dilated cardiomyopathy, both end-systolic (108 +/- 34 to 123 +/- 53 ml/m2; p = NS) and rapid filling (24 +/- 6 to 28 +/- 9 ml/m2; p = NS) volumes did not change from rest to peak exercise. A significant correlation was found between the changes in end-systolic volume at peak exercise and in peak rapid filling rate in normal subjects (r = 0.6; p < 0.05), but not in patients with dilated cardiomyopathy (r = 0.3; p = NS). In normal subjects, end-diastolic volume at peak exercise was similar to that during baseline (78 +/- 14 and 85 +/- 15 ml/m2, respectively; p = NS), whereas in patients with dilated cardiomyopathy, it was greater (164 +/- 50 vs 146 +/- 33 ml/m2; p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Prolonged asymptomatic catheter-induced left and right coronary artery spasm resistant to high dose of intracoronary nitroglycerin

A 58-year-old woman, referred to our hospital to undergo invasive assessment of mitral valve stenosis, demonstrated prolonged asymptomatic catheter-induced left anterior descending and right coronary artery spasm during coronary arteriography. Coronary spasms were not associated with ECG and arterial blood pressure changes. Intracoronary injection of nitroglycerin (300 and 600 micrograms bolus) did not resolve coronary spasm. Coronary angiography, repeated 24 hours later using the same procedure and materials, did not show any evidence of coronary artery spasm. The present clinical case is interesting for 3 reasons. First, the presence of prolonged proximal double-vessel coronary spasm not associated with symptoms or signs of acute myocardial ischemia; second, the incapacity of high dose of intracoronary nitroglycerin to resolve the coronary spasm; third, the dramatic changes in the sensitivity of coronary artery to mechanical stimulation in different days.

Peak exercise left ventricular performance in normal subjects and in athletes assessed by first-pass radionuclide angiography

The role of Frank-Starling law of the heart in determining the increase in cardiac output during exercise in humans is still controversial (e.g., the mechanisms responsible for the enhancement of left ventricular [LV] filling during the shortened diastolic interval). Ten weight lifters, 12 swimmers and 12 sedentary subjects who underwent maximal upright bicycle exercise testing were studied. First-pass radionuclide angiography was performed both at rest and at peak exercise using a multicrystal gamma camera. Compared with resting values, heart rate and cardiac index at peak exercise increased by 101 +/- 16 beats/min (p less than 0.001) and 6.7 +/- 2.8 liters/min/m2 (p less than 0.001) in weight lifters, by 96 +/- 9 beats/min (p less than 0.001) and 9.5 +/- 2 liters/min/m2 (p less than 0.001) in swimmers, and by 103 +/- 9 beats/min (p less than 0.001) and 7.3 +/- 1.8 liters/min/m2 (p less than 0.001) in sedentary subjects. Stroke volume increased by 20.5 +/- 9.8 ml/m2 (p less than 0.001) in swimmers only. End-diastolic volume at peak exercise did not change in weight lifters and in swimmers; it decreased by 8.2 +/- 8.6 ml/m2 (p less than 0.01) in sedentary subjects. A significant correlation was found between the decrease in end-systolic volume and the increase in peak rapid filling rate at peak exercise in all 3 groups (r = 0.65, p less than 0.05 in weight lifters; r = 0.59, p less than 0.05 in swimmers; r = 0.67, p less than 0.05 in sedentary subjects.(ABSTRACT TRUNCATED AT 250 WORDS)