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PubMed1993

2-Phenylethoxy-9-methyladenine: an adenosine receptor antagonist that discriminates between A2 adenosine receptors in the aorta and the coronary vessels from the guinea pig.

Substituting a methyl group for the ribose moiety of N6-substituted adenosines that are selective agonists at the adenosine A1 receptor creates antagonists that are A1-selective. Inasmuch as 2-phenylethoxyadenosine is a selective agonist for the adenosine A2 receptor, 2-phenylethoxy-9-methyl-adenine (PEMA) was synthesized and tested as a potential adenosine A2 receptor antagonist. In guinea pig hearts, PEMA antagonized with the same potency (pKB approximately 6.1) the A1-mediated negative dromotropic and inotropic actions and the A2-mediated coronary vasoactivity of the nonselective adenosine receptor agonist 5'-N-ethylcarboxamidoadenosine (NECA). PEMA at concentrations up to 30 microM did not antagonize the NECA-induced relaxations in guinea pig aortic rings. At concentrations exceeding 10 microM, PEMA caused xanthine-insensitive relaxations of both the aorta and the coronary vessels. Pharmacological resultant analysis revealed A2 receptor antagonism by PEMA in the guinea pig aorta (pKB = 5.2). The nonselective adenosine receptor antagonist 8-p-sulfophenyl-theophylline antagonized NECA responses in all four assays with equal potency (pKB approximately 5.7). Thus, PEMA does not discriminate between A2 receptors in the coronary vessels and A1 receptors in the atria of the guinea pig, but it is 10-fold more potent at antagonizing the A2 receptor in coronaries than the A2 receptors in the aorta. The data suggest that the A2 receptors in the coronary vasculature may be of the A2a subtype, whereas those in the aorta may be of the A2b subtype.

Adenine↗
PubMed2002

Minimally invasive single-vessel coronary artery bypass with the internal thoracic artery and early postoperative angiography: midterm results of a prospective study in 120 consecutive patients.

BACKGROUND: This prospective study was undertaken to determine the role of the minimally invasive direct coronary artery bypass with early postoperative angiography and midterm follow-up in 120 consecutive patients with single-vessel coronary artery disease. METHODS: Minimal access (6 to 10 cm), without complete sternotomy and no cardiopulmonary bypass, was used. The lesions were located at the proximal left anterior descending coronary artery in 95% of the patients. Routine coronary angiography was performed before discharge. RESULTS: Postoperative angiography was performed in 104 (90.4%) of those 115 patients who had coronary revascularization concluded by the mini-access method. The internal thoracic artery patency rate was 98.1% (95.2% grade A). Two (1.7%) patients presented with perioperative myocardial infarction, which led to the single in-hospital death (0.8%). Of the remaining 119 patients, 113 (95.0%) were asymptomatic. The event-free probability was 94.9% and the actuarial survival was 98.3% with 42 months of follow-up. CONCLUSIONS: For selected patients with single-vessel coronary artery disease and no major myocardial dysfunction, minimally invasive direct coronary artery bypass is a safe operation and a less invasive alternative to conventional coronary artery bypass grafting.

Adult↗
PubMed1984

Relation between electrocardiographic and scintigraphic location of myocardial ischemia during exercise in one-vessel coronary artery disease.

The purpose of this study was to determine the usefulness of exercise electrocardiography in predicting the site of myocardial ischemia. Fifty-two patients were studied who had angiographically documented 1-vessel coronary artery disease (CAD) and exercise-induced reversible thallium-201 perfusion defects. The patients were divided into 2 groups: group I (28 patients) had left anterior descending CAD and group II (24 patients) had left circumflex or right CAD. There were no significant differences between the 2 groups in severity of coronary stenosis, heart rate and systolic blood pressure during exercise. The size of the perfusion defect was larger in group I than II (28 +/- 12% vs 19 +/- 10%, p less than 0.02). There was no significant difference between the 2 groups in the frequency of ST depression in the anterior, inferior or lateral electrocardiographic leads. ST depression occurred in 16 patients (57%) in group I and 11 patients (46%) in group II (difference not significant). The sensitivity of the exercise electrocardiogram was 52% using 12 leads, 50% using 3 leads (V3, V5 and aVF) and 50% using V5 alone (difference not significant). Thus, the site of ST depression during exercise is not a good predictor of the site of exercise-induced perfusion defect or anatomic site of CAD. The use of 12 leads does not improve the sensitivity of exercise electrocardiography in patients with CAD.

Adult↗
PubMed1997

Mechanisms of limited maximum coronary flow in severe single-vessel coronary artery disease in humans due to vertical steal.

We evaluated the usefulness of a decrease in the average peak velocity from 4 to 10 minutes after infusion of dipyridamole for detecting myocardial ischemia in 50 patients, including patients with a prior myocardial infarction. The decrease in the average peak velocity from 4 to 10 minutes associated with vertical steal and combined with a coronary flow reserve of < 1.6 had a high predictive value for myocardial ischemia in patients with or without prior myocardial infarction.

Aged↗
PubMed2006

QT interval dispersion as a new marker of restenosis after percutaneous transluminal coronary angioplasty of isolated single-vessel coronary artery stenosis.

BACKGROUND: There are no reliable non-invasive markers of restenosis after percutaneous transluminal coronary angioplasty (PTCA). The aim of our study was to measure changes in QT interval dispersion after PTCA and to determine whether restenosis subsequently affects QT interval dispersion. METHODS AND RESULTS: Fifty-six consecutive patients - 41 men and 15 women (mean age: 56.2 +/-8.3 years) - with isolated stenosis of the left anterior descending artery who underwent successful PTCA were studied. A symptom-limited treadmill exercise test was performed within 7 days after PTCA and then again before repeated angiography. Repeated coronary angiography revealed restenosis in 15 patients (26.8%) and no signs of significant stenosis in 41 patients (73.2%). QT interval dispersion in the group of patients with restenosis measured before exercise increased from baseline 34 +/- 7 to 49 +/- 15 ms after 6 months (p < 0.01) and QT interval dispersion measured immediately after exercise increased from baseline 38 +/- 4 to 68 +/- 21 ms after 6 months (p < 0.001). In contrast, patients without restenosis showed no significant changes in QT interval dispersion measured before (baseline: 34 +/- 9 ms; after 6 months 33 +/- 12 ms; p = NS) and immediately after exercise (baseline: 34 +/- 12 ms; after 6 months: 33 +/- 10; p = NS). When QT interval dispersion > or =60 ms (measured 6 months after PTCA procedure) was considered as a potential marker of restenosis, this indicator had very high sensitivity and specificity when measured immediately after exercise (80 and 95% respectively). CONCLUSIONS: QT interval dispersion significantly increases in the group of patients with documented restenosis and may be a simple, non-invasive marker of restenosis. However, further studies are needed to confirm this observation.

Angioplasty, Balloon, Coronary↗
PubMedDate not supplied

[The effect of the synthetic antioxidant emoxypine on the tonus of the coronary vessels].

Intracoronary administration of emoxypine caused the dose-dependent increase in the average coronary blood flow without changing the parameters of cardiohemodynamics. Emoxypine failed to change the structure of the phase coronary blood flow. When administered at the concentration of 5.10(-4)M emoxypine increased the volume rate of the perfusate outflow from the rat isolated heart cavities and decreased the value of potassium contracture of isolated segments of the coronary vessels. The data obtained indicate the direct coronarolytic action of emoxypine.

Animals↗
PubMed1985

[Scanning and transmission electron microscopy findings in the coronary vessels in physiologic and pathologic states].

Scanning and transmission electron microscopic examinations of the coronary vessels were performed on rats, and the findings compared. Both procedures demonstrated a tightly meshed network of arterial endothelium orientated to the direction of flow, thereby allowing optimal adaptation to changes in direction of blood flow, high intervascular pressure, structures of the remaining intima components and variable states of arterial wall tension. Venous endothelium proved to possess a markedly less uniform constitution, the texture of the inner surfaces being strongly determined by the surrounding perivascular tissue. Induction of arterial hypertension in rats (via GOLDBLATT-hypertension) and in Cynomolgus monkeys (via aortic constriction), and hyperlipidemia in hypertensive rats through a fatty diet enabled the study of a wide spectrum of coronary artery endothelium disease, primarily at early stages. Both species demonstrated hypertensive endothelial dehiscence (gaps), basically passive in nature and due to increased endothelial mobility. Occasionally, peculiar cytoplasma deformations could be found surrounded by circumscribed, consecutive endothelial gaps, allowing speculation of increased contraction-like states of intraendothelial filament tension due to hypertension. Areas of intima damage were usually focal and demonstrated numerous degenerative endothelial changes, endothelium necrosis and defects. Small endothelial gaps were covered by a film of thombocytes, though this finding was seen only in monkeys. Attempts at endothelium regeneration and reparation were manifest in increased endothelial mitosis, pseudoendotheliums, endothelial giant cells and films of leucocyte aggregations covering endothelium defects. Migration of leucocytes into the intima was actively furthered through small leaks in the endothelium. Hyperlipidemic and hypertensive rats showed endothelial bloating, due in part to vacuolar intracytoplasmatic lipid deposits with phagocytosis of fine particles of cholesterin crystals.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2002

Single-vessel coronary artery stenosis: myocardial perfusion imaging with Gadomer-17 first-pass MR imaging in a swine model of comparison with gadopentetate dimeglumine.

PURPOSE: To evaluate the ability of Gadomer-17 to depict perfusion defects in a closed-chest swine model of single-vessel coronary artery disease. MATERIALS AND METHODS: Twelve pigs underwent closed-chest placement of a flow reducer for 70%-90% luminal stenosis in the proximal left anterior coronary artery. Magnetic resonance (MR) perfusion imaging with Gadomer-17 and gadopentetate dimeglumine, microsphere blood flow (MBF) testing, and technetium 99m ((99m)Tc) 2 methoxyisobutylisonitrile (MIBI) single photon emission computed tomography (SPECT) were performed during dipyridamole vasodilation. Comparisons of percentage signal intensity (SI) increase (PSIC) in remote and ischemic myocardium were made with repeated measurements analysis of variance after injection of both tracers. RESULTS: Perfusion defects and reduced PSIC in the anterior ischemic versus the inferior remote myocardium could be identified after injection of both Gadomer-17 (PSIC, 66% +/- 30 [mean +/- SD] vs 100% +/- 32, respectively; P <.001) and gadopentetate dimeglumine (PSIC, 49% +/- 31 vs 81% +/- 43, respectively; P <.005). The size of perfusion defect depicted with both tracers was highly correlated with defect size at (99m)Tc MIBI SPECT (r = 0.69, P <.05 for Gadomer-17 and r = 0.60, P =.05 for gadopentetate dimeglumine) and with areas of reduced MBF (r = 0.70, P <.05 for Gadomer-17 and r = 0.80, P <.05 for gadopentetate dimeglumine). PSIC also correlated with MBF (r = 0.89, P <.001 for Gadomer-17 and r = 0.75, P <.001 for gadopentetate dimeglumine). Gadomer-17 allowed differentiation of ischemic from nonischemic myocardium, as demonstrated by reduced PSIC (PSIC, 48% +/- 38 vs 72% +/- 31, respectively; P <.001) until 20 minutes after contrast material injection. In contrast, differentiation of ischemic from nonischemic myocardium was possible only until 55 seconds after injection of gadopentetate dimeglumine (PSIC, 36% +/- 24 vs 56% +/- 27, respectively; P <.005) but not at any time point thereafter. CONCLUSION: With the study conditions, Gadomer-17 provided more prolonged differentiation of ischemic from remote myocardium than that with gadopentetate dimeglumine.

Animals↗
PubMed1999

New minimally invasive surgical technique using arterial T-grafts for treatment of double-vessel coronary artery disease: experimental study.

Minimally invasive surgery has been used successfully in patients with single-vessel coronary artery disease (CAD), but there are no clinical reports of surgical techniques for the treatment of multivessel disease in this field using both internal mammary arteries (IMAs). Therefore a canine model has been established to demonstrate the feasibility of a minimally invasive surgical treatment of coronary artery double-vessel disease using both IMAs. Ten mongrel dogs underwent bilateral thoracoscopic preparation of both internal mammary arteries through small left lateral chest ports. Using the Port Access endovascular cardiopulmonary bypass system the right IMA (RIMA) was anastomosed as a free graft end-to-side to the left IMA (LIMA) as a T-graft. After induction of cardioplegic arrest the RIMA was anastomosed to the circumflex artery and the LIMA to the left anterior descending artery. All animals were weaned from cardiopulmonary bypass without inotropic support. The electrocardiogram showed sinus rhythm with no signs of ischemia. Intraoperative coronary angiography demonstrated patency of all anastomoses. The minimally invasive surgical treatment of double-vessel CAD using arterial T-grafts of both IMAs is thus feasible. Surgical trauma can be further reduced by harvesting the RIMA transmediastinally through the left lateral chest.

Anastomosis, Surgical↗
PubMed2004

Total arterial revascularization for multiple vessel coronary artery disease: with or without cardiopulmonary bypass.

BACKGROUND: To assess the usefulness of off-pump technique for more technically demanding coronary artery bypass procedures using exclusively arterial conduits. METHODS: Analysis of perioperative data of 324 consecutive patients in whom total arterial revascularization for multiple- vessel coronary artery disease was performed--181 cases on-pump and 143 cases off-pump. RESULTS: On average in the on-pump group 2.7 +/- 0.8 (range, 2-5) grafts per patient were constructed versus 2.4 +/- 0.7 (range, 2-4) grafts per patient in the off-pump group (P < .001). Of the total number of 490 anastomoses performed on-pump, 83 (17%) were side-to-side and of 349 anastomoses performed off-pump, 51(15%) were side-to-side, a nonsignificant difference (P = .4). The aorta was used as a site for proximal anastomosis of 1 or more arterial conduits in 105 patients (58%) who underwent on-pump surgery and in 57 patients (40%) who underwent off-pump surgery (P = .002). In the off-pump group, the right internal thoracic artery (RITA) was rarely (12%) routed through the transverse sinus to circumflex branches compared with the on-pump group (34%) (P = .017). RITA in off-pump patients was more often used to revascularize the anterior wall (47% versus 29%; P = .08). We observed no difference in mortality (1.7% versus 0%; P = .3), incidence of perioperative myocardial infarction (8.8% versus 7.7%; P = .8), stroke (1.7% versus 1.4%; P = .8), or atrial fibrillation (24% versus 19%; P = .3). We observed less inotropic support and less blood-product use in off-pump patients. CONCLUSION: Total arterial revascularization for multiple-vessel coronary artery disease may be safely performed off-pump. We observed tendency to somewhat smoother postoperative course in the off-pump group.

Adult↗
PubMed2003

Initial experiences with in vivo intravascular coronary vessel wall imaging.

PURPOSE: To evaluate potential use of a loopless internal receiver coil for in vivo coronary artery vessel wall imaging in five domestic swine. MATERIALS AND METHODS: Intravascular free-breathing black blood coronary vessel wall imaging was performed using a previously described double inversion fast spin echo technique after x-ray guided placement of an internal receiver coil in or in close proximity to the target vessel (LAD, LCX). RESULTS: Image quality using the phased array coil was reproducible, while image quality with the internal receiver coil was heavily dependent on coil position with respect to the examined artery, and likely also dependent on blood flow and/or cardiac-related coil motion. With internal coil placement in the left circumflex coronary artery, images of the left anterior descending vessel wall appeared similar or superior compared to commercially available phased array surface coil images. With coil placement in the target vessel itself, imaging was suboptimal because of the extremely high signal intensity (hotspot) in close proximity to the vessel wall, leading to low contrast between the vessel wall and the surrounding tissues and blood. CONCLUSION: In this study, we demonstrate the feasibility of in vivo intravascular coronary vessel wall imaging. Continued research is necessary to minimize coil motion and optimize coil sensitivity algorithms.

Animals↗
PubMed1985

Regional left ventricular systolic function in patients with segmental early relaxation and single-vessel coronary artery disease.

The purpose of this study was to determine whether systolic function is compromised in segments of the left ventricle that manifest early relaxation and are supplied by a diseased coronary artery. Regional fractional area of shortening (FAS) was evaluated from resting ventriculograms of 24 patients. Nine patients had no cardiac disease or segmental early relaxation (SER) and served as controls. Fifteen patients had single-vessel coronary artery disease (60% to 95% diameter stenosis of the left anterior descending coronary artery). Among these 15 patients, seven had no evidence of SER and eight had SER localized to the anterior wall. In patients with coronary disease and SER, and FAS of the anterolateral segment, 1.30 +/- 0.08, was greater than either controls, 1.07 +/- 0.12 (p less than 0.01) or patients with coronary disease but no SER, 1.03 +/- 0.19 (p less than 0.01). Among patients with coronary disease and SER, the FAS of the anterolateral segment was greater than the corresponding diaphragmatic segment (1.30 +/- 0.08 vs 0.97 +/- 0.12) (p less than 0.001). There was no difference in the FAS between these two segments in either controls or in patients with coronary disease, but without SER. These results indicate that SER of the anterior wall in patients with disease of the left anterior descending coronary artery is associated with enhanced systolic function of the anterolateral region. This observation is incompatible with the concept that ischemia is an underlying mechanism of SER.

Adult↗