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Biomedical subjects

R Bugiardini

Publications and source records attributed to R Bugiardini.

At least 37 records · Page 2Linked to original sources
PubMed1987

Effect of oral levodopa and carbidopa on coronary spasm in variant angina pectoris.

The effect of oral administration of 500 mg of levodopa with 50 mg of carbidopa, a peripheral dopadecarboxylase inhibitor, on coronary vasomotion during vasoconstrictor stimuli was examined in 15 patients with variant angina presenting with hyperventilation-induced myocardial ischemia. Patients were studied during 3 noninvasive sessions and 1 angiographic session. In all sessions the basic protocol consisted of provocation of coronary spasm by hyperventilation before and 2 hours after levodopa and carbidopa administration. During angiography, great cardiac vein blood flow, right atrial and aortic pressures were measured, and coronary angiograms were recorded at baseline and 1 to 4 minutes after each hyperventilation. Samples for dopamine plasma levels were drawn before and throughout the studies. In 3 selected patients, levodopa and carbidopa were associated with 30 mg of domperidone, an antagonist of dopamine peripheral receptors. Levodopa and carbidopa consistently prevented the occurrence of ischemia after hyperventilation in 6 of the 15 patients. This was due to inhibition of local coronary spasm in 2 patients and reduced coronary constriction in 4. Ischemia due to hyperventilation was still prevented despite addition of domperidone with levodopa and carbidopa. Plasma dopamine levels were 23 +/- 15 before and 739 +/- 284 pg/ml 2 hours after administration of levodopa and carbidopa. These findings are consistent with either a decreased central dopaminergic activity and associated disregulation of vasomotor tone, or a peripheral vasodilatory effect of increasing dopamine.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1987

Myocardial ischemia during intravenous prostacyclin administration: hemodynamic findings and precautionary measures.

This study reports coronary and systemic hemodynamics, and metabolic responses to atrial pacing, prostacyclin (PGI2), and iloprost, its stable analogue, in 16 patients with severe coronary obstruction as well as predominant narrowing in the left anterior descending artery. PGI2 caused ischemia in six patients with low anginal threshold during pacing. In three of them ischemia was also precipitated by iloprost. Drugs were infused at therapeutic doses and were discontinued when pain occurred. Angina disappeared promptly (less than or equal to 3 minutes) and spontaneously after the infusion of PGI2, whereas after the analogue it was long lasting (greater than or equal to 5 minutes) and was relieved by 125 mg intravenous aminophylline, an antagonist of dipyridamole-induced coronary dilation. Ischemia was associated with a drug-induced decrease in arterial blood pressure and reflex tachycardia, and occurred despite increased great cardiac vein (GCV) blood flow and decreased resistance, which is consistent with either a failure of regional flow to increase proportionally to the metabolic demand or a subendocardial-subepicardial steal. However, the following findings favor the latter hypothesis: heart rate and rate-pressure product at the onset of pain were lower with drugs than with pacing, and GCV blood flow, measured at a comparable heart rate, was less with pacing than with drugs. In conclusion, PGI2 and analogues may induce ischemia in patients with advanced coronary artery disease. The mechanism appears to be related to a dipyridamole-like maldistribution of flow. Counteraction of ischemia can be achieved by aminophylline.

Cardiovascular Agents↗
PubMed1986

Effects of iloprost, a stable prostacyclin analog, on exercise capacity and platelet aggregation in stable angina pectoris.

The effects of iloprost, a chemically stable compound with prostacyclin mimetic activity, on exercise capacity and platelet aggregation were assessed in 24 patients with effort angina and proved critical (at least 70% diameter narrowing) coronary artery disease. Upright bicycle ergometer testing (25-W increments every 2 minutes) was performed during drug and placebo infusions using a crossover, randomized, single-blind protocol. Samples for measurements of adenosine diphosphate-induced platelet aggregation in platelet-rich plasma were obtained in all patients before and during the study. Compared with placebo, intravenous iloprost consistently (p less than 0.001) prolonged exercise duration and time to onset of significant (0.1 mV) ST depression. Angina and ST depression occurred at a greater heart rate and rate-pressure product. Benefits were remarkable in some patients (67%) and not in others. Iloprost administration resulted in reduced platelet aggregation at peak exercise in all patients, whether they had consistent or little response to the drug. Thus, iloprost administration may improve exercise capacity in patients with stable exertional angina pectoris. Improvements are independent of changes in the major determinants of myocardial oxygen demand and associated with markedly reduced platelet aggregation, which may account for increased myocardial perfusion in patients with high sensitivity to coronary constriction.

Angina Pectoris↗
PubMed1986

Differential transmyocardial platelet behavior in response to pacing and ergonovine-induced myocardial ischemia.

In 17 anginal patients with critical narrowing of the left anterior descending artery, we studied the effects of acute ischemia, either induced by atrial pacing or by ergonovine, on transmyocardial platelet behavior. Six other patients with atypical chest pain and normal coronary arteries served as controls. Simultaneous arterial and great cardiac vein samples were drawn during control and ischemia to measure the levels of platelet factor four (PF4) and beta-thromboglobulin (BTG). During pacing-induced ischemia the great cardiac vein-arterial differences of PF4 and BTG decreased significantly, indicating a reduced platelet aggregability; no significant changes were observed in the control patients. By contrast, when ischemia resulted from ergonovine-induced spasm of the left anterior descending artery (five patients), the great cardiac vein-arterial differences increased, indicating enhanced platelet aggregability. Again no differences were observed in the patients with a negative ergonovine test. The results of our study suggest that the transcardiac platelet behavior may vary during different ischemic conditions. When ischemia is due to increased myocardial demands and flow is normal or increased, myocardial metabolites released from the ischemic area may oppose platelet aggregation. By contrast, spasm and the stagnant flow resulting from it may enhance platelet aggregation.

Adult↗
PubMed1986

[Opposing effects of propranolol and diltiazem on the angina threshold during an exercise test in patients with syndrome X].

Patients with angina pectoris, exercise induced myocardial ischemia, normal coronary arteries and no evidence of epicardial spasm, i.e. patients with syndrome x, have been suggested to haven inadequate increase in coronary blood flow during tachycardia, possibly due to a functional disorder of small coronary vessels. To evaluate the best medical management of this syndrome we studied 13 patients who showed the above set of findings. Patients were given propranolol (160 mg daily), diltiazem (360 mg daily) and placebo for 2 weeks, using a randomized single blind protocol. Upright bicycle ergometer testing was performed at the end of each period of treatment. Compared to placebo, diltiazem significantly (p less than 0.001) prolonged exercise duration (x +/- SD: 365 +/- 86 vs 303 +/- 89 sec) and time to onset of angina (358 +/- 88 vs 276 +/- 90 sec). Angina appeared in 7 patients with diltiazem vs 13 patients with placebo and occurred at a higher rate pressure product (26.3 +/- 3.5 vs 24.1 +/- 2.8 X 10(-3); p less than 0.02). Conversely, following propranolol exercise duration and time to onset of angina were unchanged and angina appeared in all patients at a lower rate pressure product (18.3 +/- 2.9 vs 24.4 +/- 3.6 X 10(-3); p less than 0.001). The most likely explanations for these findings are: propranolol counteracts beta 2-adrenergic receptors, thus further reducing coronary reserve. This may lower the anginal threshold; Diltiazem reduces smooth muscle tone in small coronary vessels. This may result in increased coronary reserve and exercise duration.

Adult↗
PubMed1985

Different susceptibility to myocardial ischemia provoked by hyperventilation and cold pressor test in exertional and variant angina pectoris.

Coronary constriction at the site of atherosclerotic stenoses has been suggested to play an important role in modulating the frequency of symptoms in patients with exertional angina. To investigate whether stimuli triggering coronary constriction have similar effects in patients with exertional and variant angina, responses to hyperventilation (HV) and cold pressor test (CPT) were evaluated. Twenty patients with chronic exertional angina, positive exercise test results and coronary heart disease were compared with 14 patients with variant angina and ST-segment elevation during an ergonovine test. In patients with exertional angina, the CPT produced diagnostic ST-segment depression in 6 of 20 patients (30%) at levels of rate-pressure product much lower than those during the exercise test; all patients had low effort tolerance and severe coronary artery disease. HV produced diagnostic ST-segment depression in only 1 of 20 patients (5%) (p less than 0.05 compared to that with CPT). Conversely, in patients with variant angina, HV produced ST-segment elevation in 11 of 14 patients (78%) and CPT produced elevation in only 2 of 14 (14%) (p less than 0.01). Thus, coronary constriction can provoke myocardial ischemia not only in patients with variant angina but also in some patients with exertional angina. Furthermore, the 2 groups of patients have a different susceptibility to stimuli known to produce coronary constriction.

Adult↗
PubMed1985

Myocardial ischemia induced by prostacyclin and iloprost.

Vasodilators of resistive vessels may induce ischemia in patients with coronary artery disease. To evaluate this possibility during prostacyclin (PGI2; scalar doses up to 10 ng/kg/min) and prostacyclin analog (iloprost; scalar doses up to 6 ng/kg/min) infusions, we studied 33 patients with angina pectoris and proved coronary artery disease. Patients were also submitted to dipyridamole (0.15 mg/kg/min for 4 minutes) and exercise stress testing (starting at 25 W and increasing 25 W every 2 minutes). In a preliminary study the hemodynamic and side effects of iloprost were studied in seven healthy subjects. At an iloprost dose of 4 to 6 ng/kg/min, these subjects had a significant decrease in mean arterial pressure and total peripheral and pulmonary vascular resistances. Side effects were limited to facial flushing and slight headache and were readily reversible. PGI2 induced typical chest pain and significant ST segment depression in six patients with severe coronary artery disease (three with left main and three with triple vessel disease) and poor exercise tolerance (means +/- SD = 362 +/- 99 seconds). All six patients had had angina during the dipyridamole infusion. Similar findings were observed after iloprost infusion in four of these. Aminophylline (125 mg iv) completely relieved chest pain. Although the rate-pressure products occasionally rose during PGI2 and iloprost infusions, there were no significant changes between ischemic (11.3 +/- 2.3 and 10.6 +/- 1.4 X 10(-3) U) and preischemic (10.8 +/- 1.5 and 10.7 +/- 1.4 X 10(-3) U) rates of infusion. Our data indicate that PGI2 and iloprost may induce ischemia independently of changes in oxygen demand, and suggest that these drugs dilate small coronary vessels. This may result in decreased subendocardial perfusion pressure and/or "coronary steal."

Adult↗
PubMed1985

[The relation between myocardial oxygen consumption and ischemia during exertion in patients with angina pectoris: effect of propranolol].

Patients with coronary artery disease exhibit a reduced coronary vasodilator reserve in response to exercise testing. Drugs which block coronary beta adrenergic receptors could exacerbate this abnormality leaving the vasoconstrictor alpha tone unopposed and/or counteracting the beta 2-mediated vasodilation elicited by the increase in myocardial oxygen demand. To test this hypothesis we administered propranolol 40 mg qid and placebo, using a cross over randomized single blind protocol, to 14 patients each with effort angina and critical coronary stenosis (greater than or equal to 75%). We performed computer-assisted multistage bicycle ergometer testings (25 W increments at 2 min intervals) after 2 weeks open label placebo (control) and at 2 week intervals following daily administration of propranolol and placebo. Compared to placebo, propranolol reduced significantly (p less than 0.001) peak heart rate (x +/- SD: 114 +/- 6 vs 150 +/- 11 beats/min) and rate pressure product (20.1 +/- 2.1 vs 28.0 +/- 3.9 X 10(-3)) and increased exercise duration (462 +/- 91 vs 355 +/- 85 sec). Conversely 0.1 mV ST segment depression was observed at lower heart rate (106 +/- 9 vs 127 +/- 8 beats/min, p less than 0.001) and rate pressure product (16.9 +/- 3.6 vs 22.4 +/- 2.4 X 10(-3), p less than 0.001). No significant differences were found between placebo and control. Moreover, we assessed the regression lines of the relationship between ST segment depression (ST) and heart rate (HR) during exercise. These have been shown to be shifted to the right after surgical revascularization and are an indirect measure of coronary reserve.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

[Myocardial ischemia induced by the cold pressor test in patients with exertion angina. Case contribution].

The aim of the present study was to assess the incidence of myocardial ischemia during cold pressor test in patients with stable exertional angina pectoris. Thirty-seven patients with proven coronary artery disease were submitted to cold pressor and exercise stress testing; computer assisted electrocardiographic recordings were obtained throughout the examinations. Cold stimulation provoked electrocardiographic signs of subendocardial ischemia only in 3 patients. They had suffered of a previous myocardial infarction and showed low exercise tolerance and severe coronary lesions (one with triple vessel and 2 with left main disease). Interestingly, only one of these patients gave an history of angina during cold exposure. Thus these data indicate that chest pain and electrocardiographic signs of ischemia are an uncommon event during cold pressor stimulation which occurs more likely in patients with fairly severe coronary narrowings. More sensitive markers of ischemia and/or different modalities of cold application are required for studies concerning the relationship between cold exposure and angina pectoris.

Angina Pectoris↗
PubMed1985

[Changes in angina threshold induced by administration of ergonovine maleate during pacing in patients with chronic exertional angina].

It is widely accepted that the occurrence of chest pain and/or ST segment elevation during ergonovine testing is a hallmark of abnormal coronary constriction. However, the negativity of this test cannot be considered as an incontrovertible proof of the absence of coronary sensitivity to vasoconstriction. Indeed, it could only indicate that the resulting effect is inadequate to critically reduce coronary blood flow. To test this hypothesis we studied 12 patients with proven coronary artery disease and negative ergonovine test who had complained of chronic exertional angina pectoris and referred variable threshold for the occurrence of pain. They were submitted to atrial pacing (starting from 90 bpm, with 10 bpm increments every 2 min) before (control) and after ergonovine administration (total dose = 0.675 mg). Time, heart rate and rate pressure product were evaluated at the onset of angina and significant ischemia (0.1 mV ST segment depression). After ergonovine, angina was achieved earlier (405 +/- 173 vs 526 +/- 180 sec, p less than 0.005) than during control and at a lower heart rate (116 +/- 15 vs 131 +/- 15 bpm, p less than 0.001) and rate pressure product (15.8 +/- 2.0 vs 18.8 +/- 2.3 X 10(3) U, p less than 0.001). Changes in anginal threshold were widely variable among cases being that the time to onset of pain was dramatically reduced in certain patients but unchanged in one. Similar results were obtained when substituting the ischemic to the anginal threshold. Thus, negativity to ergonovine testing does not imply the absence of coronary constriction which may be revealed when increasing myocardial oxygen demand by atrial pacing.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1984

Evaluation of the effects of catheter sampling for the study of platelet behavior in the pulmonary and coronary circulation.

To study the effects of sampling through cardiac catheters on indices of platelet function, we measured the levels of platelet factor 4 (PF4), beta thromboglobulin (BTG), and platelet aggregate ratio (PAR) in 10 patients with atrioventricular accessory pathway (AVNAP), six patients with primary pulmonary hypertension (PPH), and six patients with critical narrowing of the left anterior descending artery (LAD). In AVNAP and LAD patients samples were drawn simultaneously from a peripheral vein, coronary sinus, and brachial artery; in AVNAP patients samples were also obtained from the axillary vein before the coronary sinus was entered. In PPH patients samples were drawn from pulmonary artery, aorta, and a peripheral vein; in these patients the effects of an intravenous infusion of prostacyclin (PGI2) (2 to 8 ng/kg/min) on PF4, BTG, and PAR were also studied at all sampling sites. In all patients arterial, coronary sinus, pulmonary arterial, and axillary venous levels of PF4, BTG, and PAR significantly exceeded those measured in the peripheral vein. PGI2 infusion resulted in a significant decrease of PF4 at all sampling sites, while no consistent BTG changes were observed and PAR levels did not decrease in the peripheral vein. Although a considerable interpatient variability in PF4 levels was observed, a significant (r = 0.91) correlation was found in patients with AVNAP between simultaneous coronary sinus and arterial PF4 levels. The value of PF4 coronary sinus-arterial difference in LAD patients was consistently higher than that calculated in AVNAP patients (54.5 +/- 28.9 vs 4.2 +/- 3.8 ng/ml).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗