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Transoesophageal and epicardial echocardiography are indispensible intraoperative imaging modalities to guide paediatric heart disease surgeries and influence surgical decision-making. A less well-described role of intraoperative imaging is its utility in evaluating coronary artery patency and flow. Focused two-dimensional, colour, and spectral Doppler imaging of the coronary arteries should be performed during surgeries involving coronary manipulation or re-implantation, or in cases where there is unexpected ventricular dysfunction or electrographic signs concerning for ischaemia. Intraoperative imaging allows for any anatomical issues to be detected and addressed promptly in the operating room. Imaging of the coronary arteries should identify unobstructed coronary ostia and proximal course without kinking, angulation, narrowing, or significant calibre change to suggest stenosis or extrinsic compression from neighbouring structures. The aim of this review is to highlight the usefulness of transoesophageal and epicardial echocardiography in evaluating coronary artery patency and flow, provide a how-to guide for optimal imaging, and to introduce a practical guideline to achieve best clinical practice.

Bioresorbable vascular scaffolds (BVSs) represent the newest tool in the treatment of coronary artery disease (CAD). Conversely to the previous metal stents and thanks to the polylactate-based backbone, BVSs could be visualized by magnetic resonance imaging (MRI) without artifacts. These properties allow a potential non-invasive assessment of coronary artery patency after percutaneous coronary intervention (PCI), avoiding cardiac catheterization included iodine contrast and radiation exposure, and potentially more sophisticated imaging tool as the optical coherence tomography (OCT). We reviewed the available medical literature on the coronary MRI evaluation of BVS after PCI, also discussing its potential diagnostic role in the long-term follow-up of these patients.

The aim of the present study was to assess the effectiveness of standard medical therapy in lowering the risk of cardiovascular death in the remote period after myocardial revascularization (MR), taking into account the presence of renal dysfunction. Material and Methods: The study included 90 patients with coronary heart disease (CHD) and indications for revascularization. We evaluated a drug therapy obtained at different stages of revascularization, as well as the severity of patients’ condition and the prevalence of renal dysfunction. Results: In the remote period after MR (5.8±0.05 years), 71/78.9% patients participated in the study; death occurred in 10/12.3% patients. The duration of therapy for chronic myocardial ischemia before MR (P=0.005), as well as compliance with prescribed therapy during 6 months (P=0.008) after this procedure, affected cardiovascular death in the remote period after MR. Using statins before MR reduced the risk of cardiovascular death by 17.2% (P=0.01), beta-blockers -14.95% (P=0.04), and ACE inhibitors (ACEIs) - 15.75% (P=0.03). The lack of regular use of acetylsalicylic acid (ASA) for 6 months after RM was associated with an increase in the risk of cardiovascular death up to 36.2% (P=0.005). Statins and ACEIs are drugs that reduce the risk of cardiovascular death in the presence of renal dysfunction (P

Vascular response after coronary angioplasty varies according to the technique. Acute response after balloon angioplasty is characterized by luminal gain in most cases, although dissection can occur during the procedure, putting coronary artery patency at risk. Arterial “elastic recoil”

Acute myocardial infarction (MI) is a life-threatening condition rarely encountered in neonates. The patients usually present with sudden cardiogenic shock. Clinical management in neonates is extremely challenging. If treatment is delayed, the prognosis is dismal. We report on a 4-day-old full-term male newborn presenting with acute MI and cardiogenic shock secondary to proximal thromboembolic occlusion of the left descending coronary artery. Hemodynamic stabilization could only be achieved after extracorporeal membrane oxygenation (ECMO) support. Coronary artery patency restoration was performed by selective intracoronary lysis with recombinant tissue plasminogen activator (r-tPA). ECMO support could be discontinued and myocardial function recovered within 6 weeks. We discuss the potential etiologies of acute perinatal MI and the role of ECMO support in the immediate post-MI period. Prompt recognition, timely referral to a cardiac center with availability of specialized advanced treatment options, and management in an orchestrated interdisciplinary approach are crucial for achieving a good outcome.

BackgroundOutcome in ST-segment elevation myocardial infarction (STEMI) is affected by patency of the infarct-related artery (IRA) on the initial angiogram. There is a controversy if preloading with antiplatelet drugs affects initial IRA patency in case of shortening transportation time for primary percutaneous coronary intervention (PCI). The aim of the study was to assess the relation between IRA patency and platelet reactivity on admission after preloading with aspirin and clopidogrel within 2h to primary PCI.MethodsThe study included 49 subjects who received 600mg of clopidogrel and 300mg of aspirin and underwent primary PCI within 120min from loading. Platelet reactivity testing was performed on admission with means of impedance aggregometry after induction with arachidonic acid (ASPItest) and adenosine diphosphate with prostaglandin E1 (ADPtest HS) to assess response to aspirin and clopidogrel, respectively. IRA patency was defined as TIMI flow 2 or 3 on the initial angiogram.ResultsPatent IRA on the initial angiogram was found in 20 patients (41%). Median time between preloading with antiplatelet drugs and primary PCI was 64min (IQR 59–84min). Patients who received clopidogrel earlier than 84min before PCI (fourth quartile) had more suppressed platelet reactivity than patients in the first quartile (

Multidetector computed tomography has been shown to be useful in the evaluation of coronary artery bypass grafts in previous studies. We studied the accuracy of multidetector computed tomography in the detection of patency and significant stenosis of both grafts and native postanastomotic coronary arteries.Ninety-six patients with 216 grafts (98 left mammary artery, 8 right mammary artery, 8 radial artery, and 102 venous grafts) were investigated by 16-slice computed tomography. Native postanastomotic coronary arteries were also evaluated. Patients unable to maintain a breath hold of 40 s were excluded. Computed tomography data were compared with the results of conventional angiography.On a segment-based model, the overall feasibility of computed tomography was 98.1% (212 of 216 grafts) for bypass grafts and 93.1% (201 of 216 segments) for postanastomotic coronary arteries. The leading cause of unfeasibility for postanastomotic coronary arteries was the small diameter of the examined vessel (1.5 mm). Computed tomography correctly diagnosed all the 25 occluded grafts. Of the 33 significant stenoses of grafts, computed tomography correctly diagnosed 31. Sensitivity, specificity, positive predictive value, and negative predictive value were 100%, 98.5%, 96.5%, and 100%, respectively, for bypass graft; and 100%, 97.7%, 85%, and 100%, respectively, for coronary arteries. On a patient-based model, the feasibility, sensitivity, specificity, positive predictive value, and negative predictive value were 89.4% (86 of 96 patients), 100%, 93%, 86.4%, and 100%, respectively.Multidetector computed tomography allows a very accurate assessment of arterial and venous conduits and of postanastomotic native coronary arteries in patients with previous bypass graft. Despite high feasibility (93.1%), limitations of the method were breath-hold duration (35 to 40 s) and postanastomotic assessment of small vessels (which, however, precluded the analysis in only 4.6% of cases).

Background Accurate assessment of coronary stents after PCI using non-invasive imaging remains challenging despite technological improvements. New bioresorbable vascular scaffolds (BVS) have recently become available promising improved non-invasive imaging properties, which however have not be examined specifically yet. Therefore we investigated CT and MRI visualization properties of the only two CE-marked coronary BVSs. Methods The Abbott Absorb and the Elixir DESolve BVS were placed in plastic tubes filled with contrast agent and scanned with a latest generation CT respectively MR system. For CT image quality was assessed by two blinded, independent readers and in-scaffold diameter difference as well as in-scaffold attenuation difference were measured. For MRI in-scaffold signal intensity, in-scaffold lumen visibility and in-scaffold signal homogeneity were measured. Results In CTA both BVSs showed no significant difference to nominal tube diameter (DESolve 101%, Absorb 100%) and to nominal tube attenuation (DESolve 96%, Absorb 98%) and were both rated with the highest score for unrestricted lumen visualization. In MRA both BVSs showed unimpaired signal intensity (DESolve 103%, Absorb 100%), lumen visibility (DESolve 92%, Absorb 89%) and lumen homogeneity (DESolve SD 7.1%, Absorb SD 9.5%) when compared to the unstented tube. There was no significant difference between CTA and MRA results of both BVSs. Conclusions Coronary BVSs show no relevant impairment for subjective and objective measures of in-stent lumen visualization by CT and MRI and will therefore allow reliable non-invasive assessment of coronary artery patency after PCI with deployment of a BVS, which is an (additional) advantage when compared to conventional stents.

Background Current thrombolytic–antithrombotic regimens in acute myocardialinfarction (AMI) are limited by incomplete early coronary reperfusion and by reocclusion and reinfarction. We compared the effects of low molecular weight heparin (LMWH) versus unfractionated heparin (UFH) as an adjunct to recombinant tissue-plasminogen activator (alteplase) on coronary artery patency and clinical outcomes in AMI. Methods Patients with AMI treated with alteplase \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \((n=439)\) \end{document} were randomised to either subcutaneous dalteparin (120IU/kg every 12h) for 4–7 days or intravenous infusion of UFH for 48h. Coronary angiography was performed between day 4 and hospital discharge. Clinical events and safety were evaluated until day 30. Results Overall there were higher thrombolysis in myocardial infarction (TIMI) flows in the infarct related coronary artery in the dalteparin group \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \((p=0.016)\) \end{document}. The predefined primary end-point, TIMI grade 3 flow, did not reach statistical significance (dalteparin 69.3% versus heparin 62.5%; \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(p=0.163\) \end{document}). However, TIMI 0-1 flow (13.4 versus 24.4%; \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(p=0.006\) \end{document}) and its combination with intraluminal thrombus (27.9 versus 42.0%;\batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(p=0.003\) \end{document}) were less common in the dalteparin group. During the period of randomised treatment there were less myocardial reinfarctions in the dalteparin group \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \((p=0.010)\) \end{document} but after cessation of dalteparin there were more reinfarctions resulting in no difference in death or MI at 30 days. There were no significant differences in major bleeding or stroke after 30 days. Conclusions In alteplase treated AMI adjunctive dalteparin for 4–7 days seems to reduce the risk of early coronary artery occlusion and reinfarction. However, early after cessation of treatment there is a raised risk of events, which might eliminate any long-term gains.

Thrombolytic therapy revolutionised the management of acute myocardial infarction (AMI). The ability to re-establish coronary artery patency with intravenous thrombolytic drugs has transformed our therapeutic approach, despite patency failures and re-occlusions. However, the established agents are not perfect and a number of novel thrombolytic drugs have consequently been developed and evaluated. This article reviews the currently available agents, discusses available adjunctive therapies and examines the future developments that may affect the application of this therapy.

Background Continuous ST monitoring has during the past decade become widespread in coronary care units (CCU) and is now even recommended by international task forces to survey patients with acute coronary syndromes. ST monitoring has also been shown to be a well-validated technology to predict prognosis and coronary artery patency in patients with acute ST-elevation infarction. However, all evaluations in previously presented trials have been made inside a core laboratory by specially trained personnel. Methods In the Assessment of the Safety and Efficacy of a New Thrombolytic (ASSENT 2) ST-monitoring substudy, 448 patients with ST-elevation infarction from 22 hospitals were monitored by vectorcardiography. The local nurse responsible for the patient made an evaluation of the ST trend curve. This was compared with a blinded core laboratory evaluation and examined versus 30-day mortality. Results No significant differences were found between the local and central evaluations of ST-segment recovery. The accuracy of the local evaluation, compared with the central one, in deciding whether patients had ≥50% ST-segment recovery at 60 or 90 minutes was >90%. A large low-risk group (30% of the patients) with 0.8% 30-day mortality could be identified by the local evaluation. Conclusions ST monitoring with vectorcardiography can accurately be done in the clinical setting. The local evaluation was as least as accurate as the core laboratory evaluation in predicting prognosis. (Am Heart J 2001;142:58-62.)

Thrombolytic agents are a first-line therapeutic option for establishing coronary artery patency in acute myocardial infarction. Three fibrin-specific thrombolytics--alteplase, reteplase, and tenecteplase--are available in the United States and have undergone preliminary patency trials and large randomized, comparative, survival studies. Patency rates differ among them, although overall mortality benefit is similar. Because of this fact and the economic impact of the drugs, competition in this market is significant. Distinguishing features of the drugs will likely influence selection. Reteplase and tenecteplase offer ease of administration with bolus dosing. Increased fibrin specificity appears to play a significant role in separating them. Tenecteplase, the most highly fibrin specific, is associated with decreased risk of noncerebral bleeding and reduced need for blood transfusions in all patients, as well as longer survival in those with late presentation acute myocardial infarction. Current trials will reveal the role of these agents in combination with glycoprotein lIb-IIIa receptor antagonists.

Background: Established tenets of occurrence of reperfusion ventricular arrhythmias in acute myocardial infarction (AMI) do not provide insight into the timing of achieving reperfusion or whether coronary artery patency is sustained. We assessed the significance of ventricular arrhythmias in the non-invasive prediction of timely reperfusion and sustained restoration of coronary patency after thrombolysis in patients with AMI.

Continuous ST-segment analysis is an accurate and noninvasive tool for monitoring coronary artery patency in patients with acute myocardial infarction. This type of monitoring also is easy to use and cost-effective. The critical care nurse plays a pivotal role in initiating ST-segment monitoring, promptly detecting ST-segment changes, and rapidly intervening to achieve myocardial reperfusion.

In patients who have ST-segment elevation myocardial infarction (STEMI), a patent infarct-related artery on the initial angiogram is associated with improved clinical outcomes, including decreased mortality. The present study assessed the influence of administering aspirin, beta blockers, statins, and angiotensin-converting enzyme inhibitors before STEMI on infarct-related artery patency. Our data demonstrate that patients who have STEMI and receive these medications on an outpatient basis before the event have a higher likelihood of having a patent infarct-related artery compared with patients who do not receive these medications. Further, our data demonstrate a graded association according to the number of such medications being administered: the likelihood of a patent infarct-related artery increased to50% as the number of these medications increased.

AIM To evaluate the diagnostic value of ultrafast CT in comparison to established methods in cardiology. MATERIAL AND METHODS Cine and flow studies were performed in 30 patients with cardiac diseases on evolution CT. Cardiac structure and function were analysed visually and quantitatively (left ventricular ejection fraction, left ventricular myocardial mass, patency of coronary arteries, perfusion of left ventricular myocardium). The CT findings were compared with echocardiographic and angiographic findings. RESULTS Cardiac structure, functional parameters and disorders of myocardial contraction were clearly detectable by ultrafast CT, which proved inferior in assessing cardiac valves. The patency of the first and second third of normal main coronary arteries could be estimated correctly. The estimation of the distal third, of obstructed coronary arteries and of the role of collaterals was impossible. Ten of 16 areas of myocardial infarction showed low or no enhancement. CONCLUSIONS Ultrafast CT excellently reflects cardiac structure and function. It is an alternative to echocardiography. In view of the results of coronary artery patency one can hope that part of cardiac catheterisation would be avoidable in future.

Non-invasive assessment of coronary artery patency has been attempted with different imaging modalities over the last few decades. The continuous motion of the heart, the respiratory movement, together with the small and tortuous nature of the coronary arteries, made this a technically challenging task. Over the last decade, significant advances in computed tomography (CT) technology helped CT coronary angiography (CTCA) to evolve as a non-invasive alternative to conventional catheter based coronary angiography. Clinical experience with CTCA has since grown rapidly and led to its acceptance as a useful diagnostic technique for coronary artery disease in certain patient populations. Recently, there has been exponential growth in the availability and use of CTCA in several centres across the world. In order to appreciate the potential impact of CTCA on current clinical practice, it is important to understand its advantages and limitations and its clinical performance in comparison with established techniques.

Percutaneous transluminal coronary angioplasty may be complicated by the occurrence of major coronary artery dissection, which may precipitate critical myocardial ischemia, necessitating urgent surgical intervention. We report two cases of massive dissection following angioplasty, in which novel methods were used to stabilize arterial integrity. In the first, laser balloon angioplasty was used to repair the dissection; in the other, a coronary stent was inserted. In both cases, coronary artery patency was achieved with reperfusion of the distal coronary bed, thus avoiding the need for acute surgical intervention. Both patients are free of limiting symptoms at follow-up.

Successful reperfusion following thrombolysis results in increased heart rate variability in the first 24 hours after administration. Preservation of autonomic function may contribute to improved prognosis when coronary artery patency is restored with intravenous thrombolysis.

Myocardial reperfusion is the treatment of choice in acute myocardial infarction. Pharmacological thrombolysis restores coronary artery patency in about two thirds of patients with acute myocardial infarction. However, mechanical reperfusion with primary angioplasty and stenting achieves higher patency rates with less complications, especially in high-risk patients. Adjunctive pharmacotherapy and new device technology may improve the outcome of primary angioplasty. Facilitated angioplasty using a combination of half-dose thrombolysis, platelet glycoprotein IIb/IIIa antagonists, and early intervention, appears to be a promising strategy for the treatment of acute myocardial infarction in the modern era. The efficacy and safety of this approach are currently evaluated in several ongoing trials. Copyright 2003, Elsevier Science (USA). All rights reserved.

In contrast to the large body of information regarding graft patency, data regarding atherosclerosis progression and vessel patency in surgically bypassed native coronary arteries are less clear. We aimed to determine native coronary artery patency one year after CABG, and to identify clinical and

Invasive coronary angiography (CAG) is well recognized as the standard procedure in the study of coronary artery disease, especially to assess coronary artery patency or stenosis, and for the performance of therapeutic coronary intervention. 1 However, inconvenience to the patient, economic considerations of the procedure, and some incidence, albeit low, of associated complications have prompted the search for a noninvasive and safe alternative without sacrificing high diagnostic

Summary Prompt restoration of coronary artery patency in acute myocardial infarction is associated with substantial improvements in morbidity and mortality. The pivotal role of thrombolysis and aspirin in achieving these goals is well established. However, despite the success of thrombolytic therapy in large trials, clinical assessment in individual patients often suggests that reperfusion has not occurred after initial therapy. This review considers the validity of such bedside predictions and discusses whether such patients should be managed differently.

The success of current thrombolytic strategies is undermined by ongoing thrombin activity, but it is uncertain whether prevention of thrombin generation or direct thrombin antagonism is effective in achieving more optimal thrombolysis. To address this question, 24 dogs with electrically induced coronary thrombus undergoing thrombolysis with tissue-type plasminogen activator (1 mg/kg) over 20 min, were given one of the following adjunctive regimens in a random fashion. Twelve dogs received saline, and served as the control group; a direct thrombin antagonist, hirudin, was given at a dose of 20 micrograms/kg/min for 90 min to six dogs, and a selective factor Xa inhibitor, tick anticoagulant peptide (TAP), was administered to six dogs at a dose of 30 micrograms/kg/min for 90 min. The time to reperfusion was similar in the saline and hirudin groups (34 +/- 4 vs 37 +/- 7 min; P = NS) but shorter in the TAP group (21 +/- 4 min; P0.05). Coronary blood flow was restored to 100% of its baseline value for 7 +/- 2 min in control dogs, and for 20 +/- 6 min in the hirudin group (P0.05). In the TAP group, coronary blood flow was restored to 100% of its baseline value for more than 120 min in all dogs (P0.01 vs others treatments). Reocclusion occurred in 89% and 50% of dogs receiving saline and hirudin, respectively (P = NS), but in none of the TAP-treated dogs (P0.01). Plasma fibrinopeptide A (FpA) and thrombin-antithrombin III complex (TAT) levels were determined in all dogs as indicators of thrombin activation. In the saline group, FpA and TAT during reperfusion were 19 +/- 2 ng/ml and 104 +/- 24 ng/ml respectively (P0.02 vs baseline) indicating high thrombin activity. In contrast, during reperfusion in hirudin-treated dogs FpA and TAT remained similar to baseline (10 +/- 3 ng/ml and 53 +/- 4 ng/ml respectively; both P0.05 vs saline). Reperfusion in TAP-treated dogs did not alter FpA and TAT in plasma, which remained similar to baseline (9 +/- 1 ng/ml and 39 +/- 5 ng/ml respectively; both P0.05 vs saline). Scanning electron microscopy of coronary arteries showed residual thrombi with intense platelet and fibrin deposition adherent to the deendothelialized surface of the vessels following saline and hirudin therapy. In contrast, TAP-treated arteries were characterized by the absence of fibrin and minimal platelet deposition. In conclusion, these hemodynamic, biochemical and morphologic data suggest that adjunctive treatment with a higher tier blockade of the coagulation cascade is superior to direct thrombin inhibition in maintaining coronary artery patency following thrombolysis in the experimental canine electrolytic model. These findings highlight the potential adverse effects of unchecked thrombin generation in the setting of thrombolytic therapy.

The treatment of acute myocardial infarction (AMI) has changed dramatically over the past 15 years. In this issue (p. 617), Dr Gershlick presents an excellent review of strategies available to promote coronary artery patency in AMI, highlighting the limitations of thrombolytic therapy. In particular, he criticizes the preoccupation with door to needle or pain to needle time. Is there really more to optimizing myocardial salvage than timely thrombolysis?

To evaluate the cost implications of prophylactic aortic counterpulsation (IASP) to sustain coronary artery patency during acute myocardial infarction. we evaluated 102 (55%) from the 182 patients enrolled in the randomized IABP study. After coronary artery patency was established during acute cardiac catheterization, pts were randomized to IABP (N = 52) for 48 hours versus standard therapy, Control (C) = 50. During the hospitalization. pts with IASP had less recurrent ischemia (4% vs. 21%), less reinfarction (3% vs. 8%), less reocclusion (8% vs. 21%), and less need for emergency PTCA (2% vs. 11%). The duration of hospitalization (IABP = 104vs. C = 9.7 daysl and CCU stay (IABP = 4.7 vs. C = 3.9 days) were similar. The outcomes were similar in the sUbstudy compared with the overall clinical trial. Median costs were: Cath Lab $ CCU/ICU $ Non-ICU $ Total $ IABP 5,910 3,239 1,804 17,903 Control 5,679 2,781 1,851 17,913 The cost of hospitalization was significantly greater in pts with recurrent ischemia ($21,069vs. $17,492, p = 0.02) or reinfarction ($22,772 vs. $17,721, p = 0.06) compared with patients without these complications. Thus These findings suggest that a strategy of prophylactic IASP therapy after patency has been established during acute myocardial infarction while improving clinical outcomes does not increase hospitalization cost.

A case of catheter-induced spasm in a 40-year-old male one year after orthotopic cardiac transplantation is presented. The fact that spasm can occur in this setting of total cardiac denervation demonstrates that other factors can play an important part in modifying the status of coronary artery patency.

Continuous ST-segment Holter recordings were analyzed from 46 patients with acute myocardial infarction (AMI) receiving intracoronary streptokinase (SK) during the first 48 hours of hospitalization. Changes in ST deviation and the time periods of these changes were quantitated and correlated with angiographic evidence of reperfusion. Thirty-six patients had total occlusion of the infarct vessel and 10 had subtotal occlusion. Of the 36 vessels that were totally occluded, 19 were reperfused and 17 were not. In patients in whom reperfusion was successful, an ST steady state was achieved 55 +/- 32 minutes after SK administration. In patients in whom it was not successful, a steady state was achieved in 219 +/- 141 minutes (p less than 0.001). Achievement of steady state within 100 minutes after SK reperfusion indicated successful reperfusion with 89% sensitivity and 82% specificity. All patients with subtotal occlusion achieved an ST steady state before SK infusion. No patient with total occlusion achieved a steady state before SK. Achievement of ST steady state before SK infusion was 100% sensitive and 100% specific for subtotal occlusion at initial angiography. Continuous, quantitative ST-segment analysis is a sensitive and specific noninvasive technique for following coronary artery patency during AMI.

ObjectivesWe sought to assess the effect of sildenafil, a highly-specific type 5 phosphodiesterase (PDE5) inhibitor, on platelet-mediated cyclic coronary flow reductions occurring in a canine model of coronary thrombosis despite aspirin therapy.BackgroundThe PDE5 inhibitors augment the antithrombotic effects of nitric oxide in vitro and in vivo, but it has been proposed that the PDE5 inhibitor sildenafil is prothrombotic.MethodsCyclic coronary flow reductions were induced in the left anterior descending coronary artery by creation of a stenosis, endothelial injury, and thrombus formation followed by treatment with aspirin, heparin, and tissue plasminogen activator. After an initial observation period, dogs were treated with or without sildenafil (100 μg/kg bolus followed by 4 μg/kg/min infusion).ResultsCyclic coronary flow reductions ceased in five of six animals 18 ± 5 min after initiation of sildenafil but continued in all six control animals. The portion of the observation period during which the coronary artery was patent increased from 52 ± 9% to 83 ± 5% after sildenafil administration (p = 0.008) but did not differ between the first and second observation periods in untreated dogs (49 ± 11% vs. 44 ± 11%, respectively). Among animals with plasma free sildenafil levels ≥20 nmol/l, cyclic coronary flow reductions were 73 ± 12% less frequent and the time to cessation of cycling 72 ± 14% shorter than in animals with levels

A variety of therapeutic interventions are administered to survivors of myocardial infarction (MI) depending on disease severity and prognosis. For those patients who are under the care of a physician during the early hours following infarction, reperfusion of an infarct-related artery has been shown to reestablish antegrade flow in this vessel(1). It has been suggested that replenishing oxygen to the marginally-necrotic tissue can reverse myocardial injury (2,3). Nonetheless, thrombolytic therapy is not expected to reverse factors responsible for the initiation of the thrombus. As long as these exist, there is a high risk of vessel reclosure and further myocardial necrosis. The incidence of incomplete or total reocclusion within the initial forty-eight hours has been reported as high as fifteen to thirty-five percent (4,5). Thus after coronary artery patency is established, a persistent effort must be made to reduce the risk of reocclusion or recurrent ischemia following infarction.