Normal Coronary Artery Flow Research Articles

Categorising myocardial infarction with advanced cardiovascular imaging

A 66-year-old man collapsed at home with chest pain. He was found by paramedics to be in ventricular fibrillation leading to a cardiac arrest. A post-resuscitation electrocardiogram showed sinus rhythm and inferolateral ST-segment elevation. On arrival at our department he had an emergency invasive coronary angiogram which showed an occluded left circumflex artery, confirming myocardial infarction (MI). We opened the artery using a balloon, and following recanalisation, we identified a substantial filling defect indicative of a large thrombus (figure). Following stent implantation, normal coronary artery flow was restored and the patient made an uneventful recovery—although brief paroxysms of atrial fibrillation were noted on cardiac monitoring in the ensuing 24 h.

QT interval and P wave dispersion in slow coronary flow phenomenon.

BACKGROUNDSlow coronary flow (SCF) phenomenon is an angiographic finding which is defined as slow contrast passage through coronary arteries which may predispose patients to serious cardiac complications such as fatal arrhythmias. P-wave and QT-interval dispersion are electrocardiographic findings which are related to atrial fibrillation and ventricular tachyarrhythmias. In the present study, the relation between SCF and presence of P-wave and QT-interval dispersion in electrocardiography has been evaluated.METHODS47 patients with normal coronary arteries and SCF and 40 patients with normal coronary artery flow without SCF were enrolled in this case control study. Standard electrocardiogram (ECG) was analyzed for P-wave and QT-interval dispersion. SCF was identified in normal coronary vessels by use of Thrombolysis in Myocardial Infarction (TIMI) frame count (TFC) method (TFC > 27). Corrected TIMI frame count (CTFC) of coronary vessels as well as mean CTFC along with QT-interval and P-wave dispersion were compared between 2 groups. The study data were analyzed by SPSS software and P value less than 0.050 was considered to be significant.RESULTSQT-interval [76.17 (35.23) ms versus 39.25 (19.26) ms] and P-wave [39.74 (17.48) ms versus 19.50 (8.54) ms] dispersion were significantly higher among patients with SCF phenomenon (P < 0.050). In addition, there was a positive significant linear correlation between TFC and P-wave and QT-dispersion (r = 0.857, r = 0.861, respectively, P < 0.050).CONCLUSIONAccording to the results, increasing TFC among patients with SCF will result in P wave and QT interval dispersion and therefore this finding can be considered as an indicative marker for cardiac events.

PLGF expression in coronary artery smooth muscle cells is sensitive to changes in shear stress

Hemodynamic forces (stretch and shear stress) have a profound effect on the vasculature by regulating collateral artery remodeling (arteriogenesis) and development of atherosclerotic plaque. Placental growth factor (PLGF) stimulates arteriogenesis via monocyte recruitment. However, little is known about the effects of hemodynamic forces on PLGF. Based on a previous finding that arterial ligation increases PLGF in downstream collaterals, we hypothesized that PLGF is regulated by shear stress. To test this hypothesis, human coronary artery smooth muscle cells (HCASMC) were grown on the bottom of porous inserts and human coronary endothelial cells (HCAEC) were grown on the top. The HCAEC layer was then exposed to 3 levels of shear for 2 h in a cone and plate device (time‐averaged shear of 10 dyn/cm2 mimicking normal coronary artery flow; 2.5 dyn/cm2recirculatory shear simulating turbulent flow post‐stenosis; or no shear) (N=5 experiments in duplicate). Shear did not affect PLGF mRNA in HCAEC (qPCR). Interestingly, however, PLGF mRNA in HCASMC was increased by ~50% by normal shear, compared to recirculatory shear (p&lt;0.05), although HCASMC were not directly exposed to shear. Preliminary PLGF protein analysis (ELISA) was consistent with the RNA data. These findings suggest that PLGF expression in HCASMC may be regulated by hemodynamic forces in an endothelium‐dependent manner. Funding: NIH R01 HL084494 (PL).

Thrombus aspiration in ST-elevation myocardial infarction in Sweden

Percutaneous coronary intervention (PCI) with balloon angioplasty and stenting is the optimal therapy in ST-segment elevation myocardial infarction (STEMI). While this treatment alleviates the major acute problem of having an occluded or highly stenosed coronary artery, distal embolization of thrombus material and other debris often precludes restoration of normal coronary artery flow [ [1] Henriques J.P. Zijlstra F. Ottervanger J.P. et al. Incidence and clinical significance of distal embolization during primary angioplasty for acute myocardial infarction. Eur Heart J. 2002; 23: 1112-1117 Crossref PubMed Scopus (553) Google Scholar ]. Thrombus aspiration may contribute to improve coronary artery flow post PCI [ 2 Sardella G. Mancone M. Bucciarelli-Ducci C. et al. Thrombus aspiration during primary percutaneous coronary intervention improves myocardial reperfusion and reduces infarct size: the EXPIRA (thrombectomy with export catheter in infarct-related artery during primary percutaneous coronary intervention) prospective, randomized trial. J Am Coll Cardiol. 2009; 53: 309-315 Abstract Full Text Full Text PDF PubMed Scopus (298) Google Scholar , 3 Svilaas T. Vlaar P.J. van dH I. et al. Thrombus aspiration during primary percutaneous coronary intervention. N Engl J Med. 2008; 358: 557-567 Crossref PubMed Scopus (884) Google Scholar , 4 Ikari Y. Sakurada M. Kozuma K. et al. Upfront thrombus aspiration in primary coronary intervention for patients with ST-segment elevation acute myocardial infarction: report of the VAMPIRE (VAcuuM asPIration thrombus REmoval) trial. JACC Cardiovasc Interv. 2008; 1: 424-431 Abstract Full Text Full Text PDF PubMed Scopus (125) Google Scholar , 5 Burzotta F. Trani C. Romagnoli E. et al. Manual thrombus-aspiration improves myocardial reperfusion: the randomized evaluation of the effect of mechanical reduction of distal embolization by thrombus-aspiration in primary and rescue angioplasty (REMEDIA) trial. J Am Coll Cardiol. 2005; 46: 371-376 Abstract Full Text Full Text PDF PubMed Scopus (327) Google Scholar , 6 Beran G. Lang I. Schreiber W. et al. Intracoronary thrombectomy with the X-sizer catheter system improves epicardial flow and accelerates ST-segment resolution in patients with acute coronary syndrome: a prospective, randomized, controlled study. Circulat. 2002; 105: 2355-2360 Crossref PubMed Scopus (165) Google Scholar ] and it is an easy, quickly performed and cheap adjunct to PCI. However, most previous studies on thrombus aspiration have not been powered for hard clinical endpoints. To date, the only large-scale randomized trial of thrombus aspiration for STEMI to demonstrate a survival benefit is the single-center TAPAS trial in which death was a secondary end point [ 3 Svilaas T. Vlaar P.J. van dH I. et al. Thrombus aspiration during primary percutaneous coronary intervention. N Engl J Med. 2008; 358: 557-567 Crossref PubMed Scopus (884) Google Scholar , 7 Vlaar P.J. Svilaas T. van dH I. et al. Cardiac death and reinfarction after 1 year in the Thrombus Aspiration during Percutaneous coronary intervention in Acute myocardial infarction Study (TAPAS): a 1-year follow-up study. Lancet. 2008; 371: 1915-1920 Abstract Full Text Full Text PDF PubMed Scopus (746) Google Scholar ]. In recent guidelines thrombus aspiration has been upgraded to a class IIa recommendation (i.e. it is reasonable to perform the procedure) with a level of evidence: B (i.e. limited populations evaluated) [ [8] Kushner F.G. Hand M. Smith Jr., S.C. et al. Focused Updates: ACC/AHA Guidelines for the Management of Patients With ST-Elevation Myocardial Infarction (updating the 2004 Guideline and 2007 Focused Update) and ACC/AHA/SCAI Guidelines on Percutaneous Coronary Intervention (updating the 2005 Guideline and 2007 Focused Update): a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. Circulat. 2009; 120: 2271-2306 Crossref PubMed Scopus (912) Google Scholar ].

Thrombus Aspiration in ST-Elevation myocardial infarction in Scandinavia (TASTE trial). A multicenter, prospective, randomized, controlled clinical registry trial based on the Swedish angiography and angioplasty registry (SCAAR) platform. Study design and rationale

In ST-elevation myocardial infarction (STEMI), distal embolization of thrombus material often precludes restoration of normal coronary artery flow. Small-scaled studies have demonstrated that intracoronary thrombus aspiration improves flow and myocardial perfusion, but only one larger randomized single-center study has suggested a survival benefit. Thrombus aspiration is widely used in clinical practice and is recommended by international guidelines despite limited evidence. The Thrombus Aspiration in ST-Elevation myocardial infarction in Scandinavia is a multicenter, prospective, randomized, controlled, clinical open-label trial based on the Swedish angiography and angioplasty registry (SCAAR) platform with blinded evaluation of end points. A total of 5,000 patients with STEMI undergoing primary percutaneous coronary intervention (PCI) will randomly be assigned either to conventional PCI or to thrombus aspiration followed by PCI. SCAAR will be used as the platform for randomization, allowing a broad population of all-comers in the registry network to be enrolled. All follow-up will also be done in SCAAR and other national registries. The primary end point is time to all-cause death at 30 days. The Thrombus Aspiration in ST-Elevation myocardial infarction in Scandinavia trial is the largest trial to date to evaluate the effect of thrombus aspiration on death following PCI in patients with STEMI. We propose the term randomized clinical registry trial to describe the novel entity of using an online national registry as platform for case records, randomization, and follow-up.

Abstract 3351: The Coronary Suction Wave in Humans Is Not Diminished by Ischemia Induced Left Ventricular Diastolic Dysfunction.

Background: A dominant suction wave due to ventricular relaxation has been postulated to contribute to normal coronary artery flow. We hypothesised that this wave would: be present in diseased coronary arteries, occur at the appropriate time in the cardiac cycle and be diminished following coronary artery balloon occlusion due to ischemia induced diastolic LV dysfunction. Methods: Simultaneous coronary pressure - velocity and LV pressure - volume were invasively recorded at baseline and after 1 minute coronary balloon occlusion, in 10 patients with single vessel coronary disease and normal LV function. Net coronary wave intensity (WI) = (dP/dt).(dU/dt) was calculated using MatLab software. Results: A dominant forward pushing wave and a backward suction wave (figure - shaded wave) were demonstrated in diseased coronary arteries. The suction wave occurred early in diastole, during active ventricular relaxation. Ischemia induced LV diastolic dysfunction was demonstrated after coronary artery occlusion (mean % Δ from baseline (SD): LV dP/dt min = −14.8 (13.8), p=0.008, LV Tau = +19.1(14.9), p = 0.011) but there was no significant change in suction WI (mean (SD): baseline = −1.35 (0.20) m −2 s −2 x10 5 , post-balloon occlusion −1.49(0.59) m −2 s −2 x10 5 , p =0.67). Conclusion: The coronary suction wave occurs in diseased coronary arteries at the appropriate time in the cardiac cycle but is not diminished by ischemia induced diastolic left ventricular dysfunction.

Critique of the session on diagnostic testing

During the session on diagnostic testing, various diagnostic tests used to identify the cause of chest pain were discussed. This critique of diagnostic assessments of the complex etiology of chest pain is presented as a contribution toward further investigation and clarification of this difficult clinical syndrome. The first step in the evaluation process is to exclude coronary artery disease. Patients with angina and normal coronary artery flow may have atypical disease, such as microvascular angina or syndrome X. The precise relationship between these disorders and esophageal disease or gastroesophageal reflux, as well as their possible involvement in chest pain of undetermined origin, requires further definition. A limitation of esophageal provocation tests is that they may identify the esophagus as the source of pain without determining the specific esophageal disorder that causes the pain. Problems associated with 24-hour pH and pressure monitoring include (a) poor correlation between reflux episodes and heartburn symptoms, (b) the lack of a good functioning swallowing signal, and (c) the huge amount of data that must be analyzed, along with shortcomings in computer-aided analysis. Nevertheless, the various available diagnostic tests can provide important information to the clinician.