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At least 289 records · Page 16Linked to original sources
PubMed1996

Quantitative cardiac perfusion: a noninvasive spin-labeling method that exploits coronary vessel geometry.

PURPOSE: To quantitate myocardial arterial perfusion with a noninvasive magnetic resonance (MR) imaging technique that exploits the geometry of coronary vessel anatomy. MATERIALS AND METHODS: MR imaging was performed with a spin-labeling method in six arrested rabbit hearts at 4.7 T. Selective inversion of magnetization in the short-axis imaging section along with all myocardium apical to that section produces signal enhancement from arterial perfusion. A linescan protocol was used for validation of flow enhancement. Flow was quantitated from two images and validated with spin-echo (SE) imaging. Regional perfusion defects were created by means of coronary artery ligation and delineated with gadolinium-enhanced imaging. RESULTS: Linescan estimates of T1 obtained at physiologic flows agreed with model predictions. Flow-induced signal enhancement measured on SE images also agreed with expected values. Finally, perfusion abnormalities created by means of coronary artery ligation were detected. CONCLUSION: This spin-labeling method provides quantitative estimates of myocardial arterial perfusion in this model and may hold promise for clinical applications.

Animals↗
PubMed1994

Long-term prognosis of medically treated patients with acute myocardial infarction and one-vessel coronary artery disease.

Long-term prognosis was studied in 156 patients with acute myocardial infarction (AMI) with 1-vessel coronary artery disease (CAD). During a mean follow-up period of 110 months, 19 patients (14%) had reinfarction, 15 (9.6%) died (including 7 deaths of cardiac origin) and 15 (9.6%) were hospitalized for worsening of angina. A coronary arteriogram was obtained twice in 54 patients. The coronary arteriogram revealed multivessel CAD in all cases with reinfarction (n = 14). Ten percent of the patients with multivessel disease experienced a reinfarction during the initial 3 years after the onset of the first AMI. The recurrence rate of AMI in patients with 1-vessel disease increased gradually from the third year after the onset of their first AMI, reaching 10% in 6.7 years. The recurrence of AMI at the same region as the original infarction was detected in only 1 patient. Six of 19 patients (32%) with recurrence of AMI died and 13 survived after the reinfarction. It was difficult to predict future progression from the outcome of the comparison between the first and second coronary arteriograms. Thus, in patients with uncomplicated AMI with 1-vessel CAD, the prognosis is relatively good and the frequency of reinfarction is very low with conservative treatment.

Adult↗
PubMed2007

MRI of the coronary vessel wall at 3 T: comparison of radial and cartesian k-space sampling.

OBJECTIVE: The purpose of our study was to compare the quality of 3D gradient-echo images obtained using radial versus cartesian k-space sampling at 3 T. CONCLUSION: This study shows that the quality of coronary vessel wall imaging of the right coronary artery with radial k-space sampling in 3D turbo field-echo sequences is superior to cartesian k-space sampling at 3 T. Radial k-space sampling at 3 T makes it possible to combine low motion artifact susceptibility with high signal-to-noise ratio.

Adult↗
PubMed1993

[Effect of endogenous metabolites on autoregulation and dilational reserve of coronary vessels].

The experiments have been performed on isolated Langendorff rat's hearts. Perfusion pressure (PP) has been increased from 40 to 120 mm Hg by steps. It has been found out, that captopril, indomethacin and verapamil (blockers of the angiotensin-converting enzyme, eicosanoids synthesis and calcium channels, respectively) increased volume velocity of coronary flow (VVCF) at PP within the range of 80-120 mm Hg, decreased the value of the autoregulation index and the coronary vasodilatory reserve by 28-39%, apparently due to decrease of the basal tone of coronary vessels, while the maximum reactive hyperemia coronary flow was not changed thereby. The blockade of No-synthase by NG-monomethyl-l-arginine (NG-MMLA) caused reduction of VVCF at PP 40 mm Hg by 28.5%, the autoregulation index by 79% and the coronary reserve by 29% due to reduction of reactive hyperemic flow. Captopril and NG-MMLA did not change while verapamil and indomethacin decreased intraventricular pressure. Thus, the decrease of the VVCF, caused by NG-MMLA and its increase caused by addition of inhibitors could be connected with inhibition of the synthesis of substances modulating autoregulation of coronary blood flow, and obviously did not depend on changes in functional activity of myocardium.

Amino Acid Oxidoreductases↗
PubMed1991

Bombesin-like immunoreactivity in skates and the in vitro effect of bombesin on coronary vessels from the longnose skate, Raja rhina.

Bombesin-like immunoreactivity is present in nerve fibers projecting to the cardiovascular system, including the coronary arteries, and to the gastrointestinal canal, and in endocrine cells of the gut of skates belonging to the family Rajidae. Synthetic bombesin contracted isolated coronary rings from the longnose skate, Raja rhina, in a cumulative fashion. The contractile response was 84% of that of 60 mM potassium chloride. The pD2-value for bombesin was 8.83 (S.E.M. = 0.33; n = 15). Phentolamine, atropine and two substance P-antagonists increased the sensitivity to bombesin, while atenolol, sotalol, nifedipine, tetrodotoxin and two bombesin antagonists were devoid of significant effects. We conclude from this study that a bombesin-like peptide is present in nerves innervating the cardiovascular system and the gastrointestinal canal of skates of the family Rajidae, and that bombesin contracts coronary vessels in vitro via a direct mechanism and/or via mechanisms involving alpha-adrenergic and muscarinergic receptors.

Animals↗
PubMed2000

Stimulation of bradykinin B(1) receptors induces vasodilation in conductance and resistance coronary vessels in conscious dogs: comparison with B(2) receptor stimulation.

BACKGROUND: Constitutive bradykinin B(1) receptors have been identified in dogs; however, their physiological implications involving the coronary circulation remain to be determined. This study examined, in conscious dogs, the coronary response to des-Arg(9)-bradykinin (a B(1) receptor agonist) and the mechanisms involved. METHODS AND RESULTS: Eleven dogs were instrumented with a left ventricular micromanometer, a circumflex coronary catheter, a cuff occluder, a Doppler flow probe, and ultrasonic crystals to measure coronary blood flow velocity (CBFv) and coronary diameter (CD). Intracoronary des-Arg(9)-bradykinin (3 to 100 ng/kg) and bradykinin (0.1 to 10 ng/kg) did not modify systemic hemodynamics but dose-dependently increased CBFv and CD. Des-Arg(9)-bradykinin was less potent than bradykinin. Hoe 140 (a B(2) antagonist, 10 microg/kg) abolished the effects of bradykinin but did not influence the effects of des-Arg(9)-bradykinin. When CBFv increase was prevented by the cuff occluder, CD responses to bradykinin and des-Arg(9)-bradykinin were maintained. Intracoronary lisinopril (0. 75 mg) increased the CD response to bradykinin, with only minimal effect on CBFv, and extended the duration of the effect. Lisinopril did not alter des-Arg(9)-bradykinin responses. Intracoronary N(omega)-nitro-L-arginine (2 mg/kg) decreased the CD effect of bradykinin and prevented the CBFv and CD effects of des-Arg(9)-bradykinin. The relaxing effect of des-Arg(9)-bradykinin on isolated coronary rings was prevented by des-Arg(9), [Leu(8)]-bradykinin. CONCLUSIONS: In the conscious dog, B(1) receptors are present in coronary vessels, and their stimulation produces vasodilation in conductance and resistance vessels, which is mediated essentially by NO but not modulated by angiotensin-converting enzyme. However, the coronary vasodilation induced by B(1) receptor stimulation is not as great as that produced by B(2) receptor stimulation.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1997

[Acute coronary vessel occlusion after PTCA--possibility of risk stratification using quantitative coronary angiography, clinical determinants and laboratory chemistry parameters].

Abrupt vessel closure of the dilated vessel continues to represent a significant limitation of coronary angioplasty. Despite increasing operator experience and improved technology, abrupt vessel closure continues to represent the most important complication of balloon angioplasty. Intracoronary stent implantation and pharmaceutical blockade of the GPIIb/IIIa receptor serve as effective tools in the prevention of abrupt vessel closure without completely resolving this problem. About 50% of patients presenting with abrupt vessel closure exhibit additional complications including myocardial infarction, necessity of CABG or death occurring in up to 10% of acute occlusions. The purpose of this study is to evaluate if quantitative coronary angiography and assessment of clinical and laboratory data allows risk stratification concerning the probability of abrupt vessel closure. PTCA in the setting of acute coronary syndrome is associated with a markedly increased risk of abrupt vessel closure, indicating that different risk factors may contribute to the development of abrupt vessel closure in patients presenting with stable angina or acute coronary insufficiency syndromes. 798 uncomplicated PTCA procedures for stable angina pectoris were compared with 68 interventions that were complicated by abrupt vessel closure. Furthermore, 133 successful angioplasty procedures for acute coronary syndromes defined as acute myocardial infarction or unstable angina pectoris were matched with 31 procedures for acute coronary syndromes with consecutive abrupt vessel closure. In patients presenting with stable angina pectoris stenosis length, stenosis eccentricity, minimal lumen diameter, degree of the stenosis after angioplasty, female gender, and fibrinogen could be defined as independent predictors of abrupt vessel closure. In acute coronary syndromes, only minimal lumen diameter, recanalization of completely occluded coronary arteries and fibrinogen were associated with an increased risk of abrupt vessel closure.

Aged↗
PubMedDate not supplied

Regulation of large coronary vessels by adrenergic mechanisms in conscious dogs.

The effects of alpha and beta adrenergic stimulation were examined in conscious dogs on measurements of left circumflex coronary blood flow and coronary arterial diameter and on calculations of mean coronary resistance (MCR) and left circumflex coronary internal cross-sectional area (CSA). Methoxamine (50 micrograms/kg/min), after transiently increasing left circumflex coronary dimensions, induced sustained reductions in left circumflex coronary diameter (9 +/- 2%) and CSA (27 +/- 5%) at a time when mean arterial pressure rose by 65 +/- 5%, left ventricular (LV) dP/dt had decreased only slightly, and heart rate and mean coronary blood flow were at control levels. Isoproterenol, (0.1 microgram/kg/min), increased heart rate by 66 +/- 8%, LV dP/dt by 58 +/- 5%, and CSA by 17 +/- 3%, while it decreased mean arterial pressure by 12 +/- 1% and MCR by 44 +/- 5%. After beta 1 adrenergic receptor blockade and with heart rate held constant, isoproterenol did not increase LV dP/dt but decreased mean arterial pressure similarly (13 +/- 2%) and induced attenuated increases in CSA (6 +/- 1%), and decreases in MCR (17 +/- 3%). After combined beta 1 and beta 2 adrenergic receptor blockades isoproterenol induced no significant effects. Thus, in the conscious dog, large coronary vessels not only react passively to changes in aortic pressure but also undergo substantial active changes. Alpha adrenergic stimulation is sufficiently powerful to reduce CSA, despite the opposing elevation of distending pressure. Moreover, large vessels appear to be regulated by beta 1 adrenergic mediated increase in myocardial metabolic demands, as well as by beta 2 adrenergic medicated vasodilation.

Animals↗
PubMed1987

Results of 232 consecutive percutaneous transluminal coronary angioplasty (PTCA) procedures in single- and double-vessel coronary artery disease.

Over a 3-year period, we performed 232 consecutive percutaneous transluminal coronary angioplasty (PTCA) procedures in 171 patients, 132 (77%) of whom were men and 39 (23%) of whom were women. The patients' ages ranged from 26 to 85 years (average, 56.5 years). All of the patients had symptoms of coronary insufficiency, manifested by stable angina in 106 cases, unstable angina in 44 cases, post myocardial infarction angina in 19 cases, arrhythmia in 1 case, and syncope in 1 case. All PTCA dilatations were done by the same operators, using the same technique. The procedures were categorized as follows: Group 1 included 157 single-vessel PTCA procedures, which had a success rate of 87.3%; these included 52 dilatations of the right coronary artery (success rate, 84%), 94 dilatations of the left anterior descending artery (success rate, 86%), and 11 dilatations of the left circumflex system (success rate, 90%). Group 2 included 29 double-vessel PTCA procedures (58 total procedures), which had an 88% success rate, and group 3 comprised 17 vein-graft PTCAs, with an 86.9% success rate. Complications included coronary artery occlusion in 15 cases (9.0%), myocardial infarction in four cases (2.3%), and cardiac arrhythmia in one case (0.6%). There were no deaths. Fifteen patients (8.8%) underwent coronary artery bypass surgery during the same hospitalization (3.8% of these operations were performed on an emergency basis). Thirty-six patients (15.5%) had a second PTCA procedure owing to restenosis, which occurred either before the patient was discharged from the hospital (eight cases) or 3 to 30 months after the original procedure. We conclude that, when performed by experienced operators with optimal technical resources, PTCA results in an acceptable success rate; therefore, this procedure should be a satisfactory method of myocardial revascularization in well-selected patients with either single- or double-vessel coronary artery disease.

Journal Article↗
PubMed1995

Investigation of coronary vessels in microscopic dimensions by two- and three-dimensional NMR microscopic imaging in the isolated rat heart. Visualization of vasoactive effects of endothelin 1.

BACKGROUND: Nuclear magnetic resonance (NMR) imaging of macroscopic coronary vessels is rapidly advancing, whereas little attention has focused on development of NMR techniques for investigation of coronary microvessels. Such techniques would be of particular importance, since conventional methods to visualize coronary microvessels have specific limitations. The aim of our study was to develop two- and three-dimensional (2D and 3D) high-resolution imaging of coronary microvessels. Quantitative analysis of vessel size was performed in tomograms and applied to evaluate the vasoconstrictor effect of endothelin 1. METHODS AND RESULTS: Angiographic imaging was performed on an 11.75-T magnet by 2D and 3D gradient-echo pulse sequences. In tomograms, the validity of this method in providing correct vessel size was tested by phantom experiments. Experiments were carried out in the isolated constant-pressure-perfused rat heart with continuous registration of coronary flow and left ventricular pressure. NMR pulse sequences were pressure-triggered in mid diastole. Four groups of hearts were studied. In group 1 (n = 20), 2D imaging perpendicular and parallel to the long axis of the heart was performed. Cross sections of vessels with diameter > 140 microns were clearly detectable. In group 2 (control, n = 5) and group 3 (n = 13), tomograms perpendicular to the long axis were obtained before and after administration of vehicle (group 2) and 200 pmol endothelin 1 bolus (group 3). Vehicle had no effect on vessel cross section. Endothelin 1, which decreased global coronary flow by 47%, reduced vessel cross section by 38 +/- 19%. A weak but, on average, significant inverse correlation between area of cross section and vessel size was found. In group 4 (n = 10), 3D imaging was performed in 7 normal hearts and 3 hearts with anterior myocardial infarction. A 3D image of the entire coronary artery tree was obtained, revealing excellent agreement with anatomic studies. In infarcted rat hearts, occlusion of the left coronary artery was demonstrated. CONCLUSIONS: Visualization and quantification of coronary microvessels are feasible by NMR microscopy. NMR microscopy bears the potential of becoming a powerful tool for the investigation of the coronary microcirculation.

Animals↗
PubMed1975

Kinetics of the red cell washout from coronary vessels of isolated feline hearts.

Twenty seven isolated feline hearts were perfused with cell-free oxygenated Ringer-Locke solutions. The concentration of red blood cells in samples of venous outflow collected from the coronary sinuses was determined by means of a Celloscope counter. Cellular concentrations decreased gradually as the perfusion time increased, and from 10(9) to 10(5) cells per millilitre after 300 ml perfusion. When the ventricular lumens were filled with residual blood (group I, 15 cats), several red cell peaks were superimposed on the smooth exponential decay curve of red cell washout. It is suggested that the peaks were caused by ejection of red cells from the ventricular lumens into communicating branches between the ventricular lumens and coronary capillaries. In cases of blood-emptied hearts (group II, 12 cats) these peaks did not occur, and mathematical analysis showed that summing three exponential functions could approximate the whole washout curve of red cells. This suggests that the coronary circulation may be described by three red cell compartments. The functional implication of this analysis for the microcirculation in the coronary vessels was discussed.

Animals↗
PubMed1991

Comparison of exercise performance in left main and three-vessel coronary artery disease.

From a consecutive series of patients who underwent rest and exercise radionuclide angiography over several years, we retrospectively identified 34 patients with left main coronary artery disease and 103 patients with three-vessel coronary artery disease who did not have significant left main disease. The results of gated equilibrium radionuclide angiography were compared in these 2 groups. Multiple exercise hemodynamic, exercise electrocardiographic, and exercise radionuclide angiographic parameters were considered in an attempt to separate the 2 groups. The only parameter that was significantly different between the 2 groups was exercise heart rate. However, no value of the exercise heart rate could meaningfully separate the 2 groups. Despite their known difference in prognosis, patients with left main and three-vessel disease had very similar exercise performance and could not be distinguished from one another by exercise electrocardiography or exercise radionuclide angiography. The inability to distinguish these two groups is a clear limitation of noninvasive exercise modalities.

Coronary Angiography↗
PubMedDate not supplied

Potential utility of rubidium 82 PET quantification in patients with 3-vessel coronary artery disease.

BACKGROUND: Standard perfusion imaging may underestimate the extent of disease in 3-vessel coronary atherosclerosis. This study determined whether positron emission tomography quantification of perfusion reserve by use of rubidium 82 net retention defined a greater extent of disease than the standard approach in patients with 3-vessel disease. METHODS AND RESULTS: Rb-82 net retention was quantified as an estimation of absolute perfusion at rest and with dipyridamole stress by use of dynamic positron emission tomography imaging. The percent of abnormal myocardial sectors, as compared with a normal database, for a standard and quantification approach was determined. Twenty-three patients were evaluated. Defect sizes were larger in patients with 3-vessel disease (n = 13) by use of quantification methods: 44% +/- 18% of the myocardial sectors were abnormal by use of the standard approach versus 69% +/- 24% of sectors when measured by quantification of the stress-rest perfusion difference (P =.008). In patients with single-vessel disease (n = 10), defect sizes were smaller with quantification methods. CONCLUSIONS: Quantification of Rb-82 net retention to measure the stress-rest perfusion difference in the myocardium defined a greater extent of disease than the standard approach in this group of patients with triple-vessel disease. More accurate measurement of the extent of coronary artery disease could facilitate better risk stratification and identify more high-risk patients in whom aggressive intervention is required.

Aged↗