Reel syndrome: a rare presentation of a rare cause of cardiac resynchronization malfunction.

Abstract: Reel syndrome is a rare cause of pacemaker lead displacement. This case report shows a rare presentation of Reel syndrome highlighting the importance of an early diagnosis and discussing the underlying mechanism, management and prevention.

Multidetector computed tomographic coronary angiography as an alternative to conventional coronary angiography in non-coronary surgical patients.

AIM: Aim of our study was to evaluate multidetector 64-slice spiral computed tomography (MSCT) as an alternative to traditional coronary angiography (CA) to detect concomitant coronary artery disease (CAD) in patients initially admitted for non-coronary surgical procedures. METHODS: We have analyzed data of 380 consecutive patients operated from 2006 to 2008 initially admitted for aortic (N.=170) or mitral (N.=67) valve disease, ascending aorta aneurysm ± aortic valve disease (N.=99), and other (combined valve diseases, tumors; N.=44). These patients were submitted either to MSCT (Group CT, N.=112) or to CA (Group A, N.=268). Inclusion criteria to perform MSCT were no previous myocardial infarction or documented CAD, normal left ventricular function, sinus rhythm, less than 2-3 premature ventricular or atrial contractions /min. RESULTS: In Group CT, CAD was definitively excluded in 95 patients (85%) and was detected in 17; 8 of those 17 patients were subsequently submitted to CA and coronary artery bypass surgery for significant CAD. As compared to those in Group A, patients in Group CT were younger (64±15 vs. 70±10 years, P<0.0001), had less hypertension (P=0.0001), chest pain (P<0.05), peripheral vascular disease (P<0.05). NYHA class, incidence of diabetes, smoking habit, family history of CAD were similar. The incidence of operative mortality, postoperative myocardial infarction was not significantly different in both Group CT (0%) and A (0.4%) (P=NS). CONCLUSION: In selected cardiac surgical patients less invasive 64-slice MSCT can be with some limits an alternative to CA to rule out CAD, as confirmed by the absence of postoperative ischemic complications.

Applicability and clinical results of percutaneous transluminal angioplasty with a novel, long, conically shaped balloon dedicated for below-the knee interventions.

AIM: The aim of this study was to assess the feasibility, safety and efficacy of percutaneous transluminal angioplasty (PTA) in patients with critical limb ischemia (CLI) using a novel balloon designed for below-the-knee (BTK) indications. METHODS: The authors have prospectively collected baseline, periprocedural and mid-term data of all consecutive patients with CLI due to BTK disease in which PTA was attempted using a long (210 mm), conically-shaped balloon (0.5 mm tapering from proximal to distal balloon edges). The primary objective was the assessment of acute success (composite of technical, angiographic and procedural success). The secondary assessments included limb salvage rate, major (above the ankle) and minor (below the ankle) amputation, change in Rutherford class and cutaneous oxygen tension, reocclusion/restenosis, rehospitalization, and repeat revascularization after one year. RESULTS: A total of 31 patients were treated with 36 long tapered balloons. Ten patients presented with ischemic tissue loss. Target lesions were mostly occlusive and diffuse, commonly involving the tibial arteries as well as the in-flow and out-flow vessels. Acute success was achieved in 100% of the cases without periprocedural complications. Clinical improvement in functional status was obtained and maintained after an average of 12 months, with a significant (P<0.001) decrease in Rutherford class, 100% limb salvage, no major amputation and five (16.1%) minor amputations. Duplex ultrasound control showed restenosis/reocclusion in two (6.5%) cases, whereas a total of seven (22.6%) patients underwent repeat revascularization (2 [6.5%] target lesion re-PTA). CONCLUSIONS: Infra-popliteal PTA with this new, BTK dedicated, long tapered balloon in patients with CLI was feasible and safe, and was associated favorable clinical results at both acute and mid-term follow-up.

Carotid artery stenting: findings based on 8 years' experience.

PURPOSE: Carotid artery stenting (CAS) may be an alternative to surgical endarterectomy not only in high-risk patients. Few data are available regarding the long-term clinical efficacy of CAS with the use of cerebral protection devices and the incidence of restenosis. Our experience demonstrates that if certain requirements are fulfilled, CAS can be considered a safe and effective treatment with high short-and long-term success rates. MATERIALS AND METHODS: In the past 8 years, we treated 1,003 patients (1,096 arteries) affected by internal carotid artery stenosis, 93 with bilateral stenosis. Of these, 567 (51.74%) were symptomatic and 529 (48.26%) asymptomatic lesions. The preprocedural evaluation was performed with Doppler ultrasound (US), magnetic resonance (MR) angiography/computed tomography (CT) angiography and a neurological evaluation. Antiplatelet therapy was administered before and after the procedure. RESULTS: Technical success was achieved in 1,092 cases (99.6%), and a cerebral protection device was successfully used in 1,019 procedures (92.9%). The 30-day transient ischaemic attack (TIA)/stroke/death rate was 2.16%: death (0.18%) major stroke (0.45%) and minor stroke/TIA (1.53%). During a follow-up up to 8 years, restenoses occurred in 39 cases (3.57%), of which 28 were post-CAS (2.57%) and 11 post-CAS performed for restenosis after carotid endarterectomy (1%). Only five symptomatic restenoses>80% were treated with a repeated endovascular procedure. CONCLUSIONS: A retrospective analysis of our experience suggests that CAS is a safe and effective procedure with better results than endarterectomy. In up to 8 years of follow-up, CAS seems to be effective in preventing stroke, with a low restenosis rate.

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.

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 (

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.

A prospective randomized trial comparing stenting to internal mammary artery grafting for proximal, isolated de novo left anterior coronary artery stenosis: the SIMA trial. Stenting vs Internal Mammary Artery.

OBJECTIVE: To compare coronary artery bypass grafting (CABG) with percutaneous transluminal coronary angioplasty (PTCA) in patients with proximal, isolated de novo left anterior descending coronary artery disease and left ventricular ejection fraction of 45%. PATIENTS AND METHODS: In the multicenter Stenting vs Internal Mammary Artery (SIMA) study, patients were randomly assigned to PTCA and stent implantation or to CABG (using the internal mammary artery). The primary clinical composite end point was event-free survival, including death, myocardial infarction, and the need for additional revascularization. Secondary end points were functional class, antianginal treatment, and quality of life. Analyses were by intention to treat. RESULTS: Of 123 patients who accepted randomization, 59 underwent CABG, and 62 were treated with stent implantation (2 patients were excluded because of protocol violation). At a mean +/- SD follow-up of 2.4+/-0.9 years, a primary end point had occurred in 19 patients (31%) in the stent group and in 4 (7%) in the CABG group (P<.001). This significant difference in clinical outcome is due to a higher incidence of additional revascularization in the stent group, the incidence of death and myocardial infarction being similar (7% vs 7%, respectively; P=.90). The functional class, need for antianginal drug, and quality-of-life assessment showed no significant differences. CONCLUSIONS: Both stent implantation and CABG are safe and highly effective treatments to relieve symptoms in patients with isolated, proximal left anterior descending coronary artery stenosis. Both are associated with a low and comparable incidence of death and myocardial infarction. However, similar to PTCA alone, a percutaneous approach using elective stent placement remains hampered by a higher need for repeated intervention because of restenosis.

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.

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.

[Coronary heart surgery in women: the risk factors and short-term results]. / Cardiochirurgia coronarica nella donna: fattori di rischio e risultati a breve termine.

BACKGROUND: Coronary artery bypass grafting is reported to have a higher (2-3 times) mortality in women than in men, most likely due to older age, higher incidence of hypertension, diabetes mellitus, hypercholesterolemia, obesity, angina and preoperative myocardial infarction, smaller diameter of coronary arteries, and smaller body surface area. METHODS: From January 1992 to December 1997, 347 female and 2098 male patients were submitted to isolated coronary artery bypass grafting. For both groups were considered: a) clinical presentation (age, height, weight, body surface area, NYHA and CCS functional classes, incidence of preoperative myocardial infarction); b) risk factors for cardiovascular diseases (diabetes mellitus, smoking habit, dyslipidemia, hypertension, familiarity); c) concomitant diseases (obesity, chronic obstructive pulmonary disease, peripheral vascular disease, thyroid dysfunction); d) hemodynamic and anatomical data (extent of coronary artery disease, diameter of coronary arteries, left ventricular function); e) surgical procedure (number and type of grafts used, urgent procedures, incidence of redo procedures). Early (up to 30 days after surgery) results were evaluated in terms of complications and mortality. RESULTS: On admission, women were older than men (p = 0.0001), were shorter (p < 0.0001), weighed less (p < 0.0001), and had a smaller body surface area (p < 0.0001); they had more severe angina (p = 0.002), diabetes mellitus (p = 0.002), hypercholesterolemia (p = 0.003), thyroid dysfunction (p < 0.0001), their coronary arteries were smaller (left anterior descending artery, p = 0.05; obtuse marginal branch, p = 0.008; diagonal branch, p = 0.01), and had less grafts implanted at surgery (p = 0.02). There was no difference between women and men in the use of the internal thoracic artery. Women did not have a higher mortality than men (4.6 vs 3.2%). Uni- and multivariate analysis did not show extraoperative risk factors for women; for men older age (p = 0.005) and poor left ventricular function (p = 0.01) were independent predictive factors of operative mortality. CONCLUSIONS: In spite of what is suggested by the literature, coronary artery bypass grafting does not have a significant higher operative risk for women than men, probably due to surgical technique refinements and extensive use of the internal thoracic artery.

Regional distribution and timing of wall motion abnormalities during echo-dipyridamole stress test in patients with stable angina: the elusive link between coronary stenoses and myocardial ischemia.

BACKGROUND: Classic experimental studies have shown that in the presence of a flow-limiting coronary artery stenosis, myocardial ischemia during metabolic or pharmacological arteriolar vasodilation causes wall motion abnormalities, which precede electrocardiographic (ECG) changes in the myocardial regions supplied by the stenotic branch. The aim of this study was to establish whether in patients with chronic stable angina the regional distribution of wall motion changes and sequence of ischemic events are similar to that observed in experimental models, as currently believed. METHODS: The study population consisted of 20 men and 4 women (mean age 59 +/- 10 years) who were recruited on the basis of the following criteria: 1) a history of chronic stable angina without clinical and instrumental evidence of previous myocardial infarction; 2) reproducible positive exercise tests for ECG myocardial ischemia and anginal pain; 3) angiographically normal left ventricular function; 4) isolated stenosis of the left anterior descending coronary artery (LAD). Patients underwent continuous 12-lead ECG and echocardiographic monitoring during dipyridamole infusion. RESULTS: During dipyridamole infusion 3 patients (13%) did not develop echocardiographic changes, ECG changes or angina, 14 (58%) exhibited ECG changes, 18 (75%) lamented angina and 16 (67%) developed echocardiographic changes. In 5 of these 16 patients (31.5%) echocardiographic changes occurred in LAD-dependent territories only, in 5 they occurred in non-LAD-dependent territories only (31.5%) and in 6 (37%) they occurred in both LAD- and non-LAD-dependent territories. A total of 14 patients exhibited both echocardiographic and ECG changes and/or angina. In 6 of these 14 patients (43%) echocardiographic changes were the first ischemic events; in the remaining 8 patients (57%) ECG changes and/or angina were the first ischemic events. CONCLUSION: In the majority of patients during dipyridamole infusion regional wall motion changes occur in territories supplied by non-stenotic coronary artery branches; they are probably caused, therefore, by distal vessel dysfunction. Furthermore, the sequence of ischemic events is different in individual patients. These findings indicate that in stable angina the mechanisms of ischemia are multiple and that the link between coronary stenoses and myocardial ischemia is very elusive.

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.

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.

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.

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.

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.