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Biomedical subjects

F Crea

Publications and source records attributed to F Crea.

At least 73 records · Page 4Linked to original sources
PubMed1999

Comparison of response to serotonin of radial artery grafts and internal mammary grafts to native coronary arteries and the effect of diltiazem.

We studied the response of radial artery (RA) or left internal mammary artery grafts to the intraluminal infusion of serotonin in 22 consecutive patients 1 year after the operation, subsequently evaluating the effect of diltiazem in 9 patients. Serotonin causes a significant vasoconstriction of the RA grafts, but not of the left internal mammary artery grafts, whereas oral diltiazem treatment does not prevent the effect of the higher dose of serotonin on RA grafts.

Aged↗
PubMed1999

Effects of naloxone on myocardial ischemic preconditioning in humans.

OBJECTIVES: We attempted to establish whether naloxone, an opioid receptor antagonist, abolishes the adaptation to ischemia observed in humans during coronary angioplasty after repeated balloon inflations. BACKGROUND: Experimental studies indicate that myocardial opioid receptors are involved in ischemic preconditioning. METHODS: Twenty patients undergoing angioplasty for an isolated stenosis of a major epicardial coronary artery were randomized to receive intravenous infusion of naloxone or placebo during the procedure. Intracoronary electrocardiogram and cardiac pain (using a 100-mm visual analog scale) 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 the six patients of each group with a stenosis on the left anterior descending coronary artery. RESULTS: In naloxone-treated patients, ST-segment changes and cardiac pain severity during the second inflation were similar to those observed during the first inflation (12+/-6 vs. 11+/-7 mm, p = 0.3, and 58+/-13 vs. 56+/-12 mm, p = 0.3, respectively), whereas in placebo-treated patients, they were significantly less (6+/-3 vs. 13+/-6 mm, p = 0.002 and 31+/-21 vs. 55+/-22 mm, p = 0.008, respectively). In both naloxone- and placebo-treated patients, average peak velocity significantly increased from baseline to the end of the first inflation (p = 0.04 and p = 0.02, respectively), but it did not show any further increase during the second inflation. CONCLUSIONS: The adaptation to ischemia observed in humans after two sequential coronary balloon inflations is abolished by naloxone and is independent of collateral recruitment. Thus, it is due to ischemic preconditioning and is, at least partially, mediated by opioid receptors, suggesting their presence in the human heart.

Aged↗
PubMed1999

Effect of acetylsalicylate on cardiac and muscular pain induced by intracoronary and intra-arterial infusion of bradykinin in humans.

OBJECTIVES: This study assessed the algesic activity of bradykinin (BK) in humans and the effects of acetylsalicylate on muscular and cardiac BK-induced pain. BACKGROUND: Bradykinin is released by the ischemic myocardium and may be involved in the genesis of ischemic pain. METHODS: Increasing doses of BK (from 30 to 960 ng/min) were randomly infused, for periods of 2 min each, into the iliac artery of 10 patients. The same protocol was repeated 30 min after the IV administration of 1 g of acetylsalicylate. In eight other patients with coronary artery disease, the same increasing doses of BK, for periods of 2 min each, were infused into the left coronary artery. The same protocol was repeated 30 min after the IV administration of 1 g of acetylsalicylate. Time to pain onset and maximal pain severity were obtained. RESULTS: Before acetylsalicylate administration, all patients experienced pain during intra-iliac infusion of BK. After acetylsalicylate, eight patients did not experience any pain during BK infusion (p = 0.0014), and in the two remaining patients, time to pain onset and maximal pain severity were similar to those recorded before acetylsalicylate. Before acetylsalicylate administration, all patients experienced pain similar to their habitual angina during intracoronary BK infusion. After acetylsalicylate, six patients did not experience any pain during BK infusion (p = 0.0098), whereas in the two remaining patients time to pain onset and maximal pain severity were similar to those recorded before acetylsalicylate. CONCLUSIONS: Intra-iliac infusion of BK causes muscular pain, and its intracoronary infusion in patients with coronary artery disease causes cardiac pain, which is similar to their habitual angina. The BK-induced pain is abolished or reduced by acetylsalicylate, thus suggesting that acetylsalicylate-sensitive mediators, such as prostaglandins, are involved in its pathogenesis.

Aged↗
PubMed1999

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.

Adenosine Triphosphate↗
PubMed1999

Role of inflammation in the pathogenesis of unstable coronary artery diseases.

Inflammation has been shown to play a pivotal role in ischemic heart disease, in particular unstable angina. The instability that characterizes this syndrome is related to the waxing and waning of ischemic stimuli, especially thrombotic ones. Angiographically and autoptically the severity of the atherosclerotic background in unstable angina does not differ from that in chronic stable angina, but in the former mural thrombi are often found and coronary atherosclerotic plaques are characterized by an inflammatory infiltrate, mostly consisting of activated lymphocytes, macrophages and mast-cells. In addition to these local findings, systemic evidence also suggests the importance of the role of inflammation in unstable angina as platelets, neutrophils and monocytes are activated, and elevated levels of serum markers of inflammation, e.g. C-Reactive Protein, have been consistently found. CRP has been demonstrated to be a reliable marker of prognosis in coronary heart disease. The consequences of inflammation are a disruption in the dynamic balance between antithrombotic and prothrombotic activities, an altered extracellular matrix metabolism, hyper-reactivity of cells such as monocytes and smooth muscle cells, all important features of unstable angina. These findings have important prognostic implications, since markers of inflammation are associated to a worse prognosis, and may also have therapeutic implications in the near future.

Angina, Unstable↗
PubMed1999

Algogenic effects of the proximal and distal intracoronary infusion of adenosine. Pathophysiologic implications on the mechanisms of ischemic cardiac pain.

BACKGROUND: It has been hypothesized that ischemic cardiac pain might be due to a spatially restricted intense stimulation of non-specific cardiac receptors. If this hypothesis is correct a strong stimulation with an adequate stimulus of a limited myocardial region should cause more pain than a weaker stimulation of a larger myocardial region. METHODS: To test this hypothesis, we carried out a systematic study in 8 male patients (mean age 52 +/- 9 years) with uncomplicated stable angina pectoris and significant isolated proximal left anterior descending coronary artery stenosis in whom the same amount of adenosine, a known mediator of cardiac and muscular ischemic pain, was infused at the proximal and distal site of the left anterior descending coronary artery. Increasing doubling doses (from 108 to 3456 micrograms/min) or adenosine were infused for periods of 2 min each into the left anterior descending coronary artery through a 2.8 F catheter. Adenosine was infused in each patient both proximally to the first diagonal branch and distally to the last diagonal branch of the left anterior descending coronary artery. The initial infusion site, proximal or distal, was randomized. At the beginning of the study patients were asked to promptly report the onset of pain. Time to onset of adenosine-induced pain and maximal pain severity (assessed by a visual analog scale) were recorded. Twelve electrocardiographic leads were recorded throughout the study. RESULTS: Seven patients experienced pain during adenosine infusion both at the proximal and distal level. One patient experienced pain only during adenosine infusion at the proximal site. In all patients pain occurred earlier (176 +/- 125 vs 343 +/- 207 s, p = 0.005) and its severity was greater (51 mm, range 20-95, vs 27 mm, range 0-69, p = 0.002) during infusion at the proximal site. No patient exhibited electrocardiographic changes during the study. CONCLUSIONS: Adenosine infusion at a proximal coronary site causes pain which occurs earlier and is more severe than that experienced during its infusion at a distal site. These findings suggest that the intensity of ischemic cardiac pain is determined by the number of stimulated receptors rather than by the intensity of their stimulation.

Adenosine↗
PubMed1999

Circadian distribution of ischemic attacks and ischemia-related ventricular arrhythmias in patients with variant angina.

BACKGROUND: There are limited data about the circadian distribution of ischemic episodes in patients with variant angina. Furthermore, no previous study investigated whether ischemia-related ventricular arrhythmias follow a circadian variation in these patients. METHODS: The circadian variation of transient ischemia and ischemia-induced ventricular arrhythmias was assessed by cosinor methodology on 24-hour Holter recordings of 26 patients with variant angina. RESULTS: On the whole, 301 ischemic episodes were detected in the population, with premature ventricular complexes occurring in 49 of them (16%). Ischemic episodes followed a typical circadian variation (acrophase hr 02:36, p < 0.01) in the total sample. However, a significant circadian variation of ischemic episodes was detectable in the 14 patients without (n = 167, acrophase hr 04:00, p < 0.0001), but not in the 12 patients with (n = 134, p = 0.14) hemodynamically significant coronary stenoses, independently of the location (anterior/inferior) of ischemia. There was no significant circadian variation of ischemia-related ventricular arrhythmias. CONCLUSIONS: Among patients with variant angina, a clearcut circadian variation of ischemia is present in those without, but not in those with, hemodynamically significant coronary artery stenoses, thus suggesting that different pathophysiologic mechanisms may operate, at least in part, in triggering coronary spasm in these two subgroups of patients. There was no significant circadian variation of ischemia-related ventricular arrhythmias in these patients.

Angina Pectoris, Variant↗
PubMed1999

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.

Angina Pectoris↗
PubMed1999

Acute coronary syndromes in women: pathophysiology and therapeutic options.

Patients presenting with acute coronary syndromes disclose a number of gender-related differences. Women are more likely than men to have unstable angina and less likely to present with myocardial infarction. Women have a better prognosis than men among patients with unstable angina. Among patients with myocardial infarction without ST-segment elevation, men and women show similar outcomes. In contrast, among patients with myocardial infarction and ST-segment elevation, women consistently show a worse prognosis than men. This difference is not fully explained by age, comorbidities, extent of epicardial artery disease, or baseline left ventricular function, and may reflect gender differences in pathophysiological, functional and anatomical variables. Moreover, revascularization procedures and several anti-ischemic drugs appear underutilized in women.

Acute Disease↗
PubMed1998

Enhanced inflammatory response to coronary angioplasty in patients with severe unstable angina.

BACKGROUND: Systemic markers of inflammation have been found in unstable angina. Disruption of culprit coronary stenoses may cause a greater inflammatory response in patients with unstable than those with stable angina. We assessed the time course of C-reactive protein (CRP), serum amyloid A protein (SAA), and interleukin-6 (IL-6) after single-vessel PTCA in 30 patients with stable and 56 patients with unstable angina (protocol A). We also studied 12 patients with stable and 15 with unstable angina after diagnostic coronary angiography (protocol B). METHODS AND RESULTS: Peripheral blood samples were taken before and 6, 24, 48, and 72 hours after PTCA or angiography. In protocol A, baseline CRP, SAA, and IL-6 levels were normal in 87% of stable and 29% of unstable patients. After PTCA, CRP, SAA, and IL-6 did not change in stable patients and unstable patients with normal baseline levels but increased in unstable patients with raised baseline levels (all P<0.001). In protocol B, CRP, SAA, and IL-6 did not change in stable angina patients after angiography but increased in unstable angina patients (all P<0.05). Baseline CRP and SAA levels correlated with their peak values after PTCA and angiography (all P<0.001). CONCLUSIONS: Our data suggest that plaque rupture per se is not the main cause of the acute-phase protein increase in unstable angina and that increased baseline levels of acute-phase proteins are a marker of the hyperresponsiveness of the inflammatory system even to small stimuli. Thus, an enhanced inflammatory response to nonspecific stimuli may be involved in the pathogenesis of unstable angina.

Acute-Phase Proteins↗
PubMed1998

The "warm-up" phenomenon occurs in patients with chronic stable angina but not in patients with syndrome X.

Most patients with chronic stable angina show an improvement in ischemic threshold when a second exercise test is performed a few minutes after a first positive test. In this study we evaluated whether this "warm-up" phenomenon also occurs in patients with syndrome X. We performed 2 consecutive exercise tests in 14 patients with chronic stable angina and 11 patients with syndrome X. The second exercise test was performed after 10 minutes from the end of the first one, always after complete recovery to baseline of ST segment. In patients with stable angina, heart rate (108+/-18 vs 99+/-16 beats/min, p = 0.005), rate-pressure product (17,020+/-4,541 vs 15,215+/-3,734 beats/min x mm Hg, p = 0.028), and exercise time (587+/-297 vs 444+/-244 seconds, p = 0.002) at 1-mm ST depression were higher in the second test than in the first one and a significant improvement in these parameters during the second test was also observed at peak exercise. Conversely, in patients with syndrome X, there were no significant differences between the 2 tests in heart rate (128+/-18 vs 131+/-23 beats/min), rate-pressure product (19,922+/-5,153 vs 19,390+/-5,654 beats/min x mm Hg), and exercise time (592+/-243 vs 566+/-228 seconds) at 1-mm ST-segment depression. Similarly, in this group of patients, no significant differences in exercise variables between the 2 tests were observed at peak exercise. Thus, unlike patients with chronic stable angina, patients with syndrome X have no evidence of warm-up in response to repeated exercise testing.

Adaptation, Physiological↗
PubMed1998

Cost-effective pharmacological prevention of acute coronary syndromes.

The growing size of trials on primary and secondary prevention of acute coronary syndromes characterised by very broad inclusion criteria may seem logical to 'trialists', who reason that the the broader the inclusion criteria, the easier it is to recruit large numbers of patients in a short period of time and the more widely applicable are the results of the study. However, large trials with very broad inclusion criteria raise two grounds for concern for physicians. The first is that the broader the inclusion criteria for enrollment in a trial in order to prove a statistically significant benefit, the greater the heterogeneity of the study population which is likely to include both susceptible and non-susceptible patients to the tested treatment. The second is that this method of assessment rapidly increases the number of treatments that produce a statistically-significant improvement in prognosis within the same broad group of patients. On the contrary, the identification of potential responders to a specific treatment can provide a personalised form of medical care suited to the needs of each individual patient with an optimal cost-benefit ratio. This approach, however, represents a major challenge as it can only be based on the identification of homogeneous subgroups of patients with common risk factors for the development of acute coronary syndromes or of their recurrence. This challenge can only be overcome by a strong commitment in funding studies on the multiple causes of acute coronary syndromes.

Acute Disease↗
PubMed1998

Role of abnormal pain sensitivity and behavioral factors in determining chest pain in syndrome X.

OBJECTIVES: We sought to investigate whether patients with syndrome X have an abnormal perception of cardiac pain. BACKGROUND: Previous studies have reported an increased sensitivity to potentially painful cardiac stimuli in patients with syndrome X. However, it is not clear whether this increase is due to an increased perception of pain or to an enhanced tendency to complain. METHODS: We assessed cardiac sensitivity to pain in 16 patients with syndrome X and 15 control subjects by performing right atrial and ventricular pacing with increasing stimulus intensity (1 to 10 mA) at a rate 5 to 10 beats higher than the patient's heart rate. False and true pacing were performed in random sequence, with both patients and investigators having no knowledge of the type of stimulation being administered. RESULTS: No control subject had pacing-induced pain; conversely, 8 patients with syndrome X reported angina during atrial pacing (50%, p < 0.01) and 15 during ventricular pacing (94%, p < 0.001). During atrial stimulation, both true and false pacing caused chest pain in a similar proportion of patients (50% vs. 63%, p = 0.61), whereas during ventricular stimulation, true pacing caused chest pain in a higher proportion of patients (94% vs. 50%, p < 0.05). Pain threshold and severity of pain (1 to 10 scale) were similar during true and false atrial pacing, whereas true ventricular pacing resulted in a lower pain threshold (mean +/- SD 3.7 +/- 3.0 vs. 7.9 +/- 2.8 mA, p < 0.001) and a higher level of pain severity (7.3 +/- 2.7 vs. 3.1 +/- 3.5, p < 0.001) than did false pacing. CONCLUSIONS: Patients with syndrome X frequently reported chest pain even in the absence of cardiac stimulation. Yet, in addition to this increased tendency to complain, they also exhibited a selective enhancement of ventricular painful sensitivity to electrical stimulation.

Adult↗
PubMed1998

Enhanced activity of sodium-lithium countertransport in patients with cardiac syndrome X: a potential link between cardiac and metabolic syndrome X.

OBJECTIVES: This study was aimed at assessing both stimulated insulinemia and the sodium-lithium countertransport in a selected group of patients with cardiac syndrome X. BACKGROUND: Hyperinsulinemia, which is frequently present in patients with cardiac syndrome X, is often associated with an enhanced activity of the sodium-lithium countertransport, an in vitro marker of sodium-hydrogen exchange. METHODS: Fifteen patients with syndrome X and 14 matched controls were studied. After pharmacological washout, sodium-lithium countertransport was assessed from lithium-loaded red blood cells. Postload insulin levels were evaluated by a double-antibody radioimmunoassay. RESULTS: Maximal velocity of sodium-lithium countertransport was higher in patients with syndrome X compared to controls (635+/-200 vs. 324+/-49 micromol/liter/h, p = 0.001). Fourteen of the 15 patients with syndrome X (93%) presented sodium-lithium countertransport values higher than the mean +2 SD of the control group. At 120 min, 12 patients with syndrome X (80%) had plasma levels of insulin >420 pmol/liter, which corresponds to the mean value +2 SD of controls (p = 0.006). CONCLUSIONS: Both enhanced activity of the sodium-lithium countertransport and stimulated hyperinsulinemia are present in the vast majority of patients with cardiac syndrome X. As enhanced activity of the sodium-lithium countertransport has the potential to cause both glucose intolerance and smooth muscle hyperreactivity, it might represent a common cause of the metabolic and vascular alterations frequently found in syndrome X.

Biological Transport, Active↗