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  • 1
    ISSN: 1432-1440
    Keywords: Cardiotoxicity of contrast media ; Angiocardiography ; Calcium addition to ionic contrast media ; Metrizamide ; Kardiale Nebenwirkungen von Kontrastmitteln ; Kalziumzusatz zu ionischen Kontrastmitteln ; Metrizamid ; Angiocardiographie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung In einer klinischen Vergleichsstudie wurde überprüft, inwieweit die kardialen Nebenwirkungen der Angiokardiographie durch Zusatz von Kalzium zum üblicherweise verwandten Diatrizoat (Urografin 76%) und Verwendung von nichtionischem Metrizamid (Amipaque) reduziert werden können. Fünfzehn Patienten wurden hierzu unter randomisierten Bedingungen mit Diatrizoat, mit und ohne Kalziumzusatz (11,3 mmol/l), und Metrizamid (320 mg/ml Jod), in jeweils einer Untersuchung, links und rechts koronarographiert und mit Diatrizoat sowie Metrizamid zweimalig lävographiert. Im Rahmen der selektiven, links- und rechtskoronaren Injektionen bewirkt der Kalzium-Zusatz bereits eine deutliche Abschwächung der bekannten kardiodepressiven Wirkung von Diatrizoat: Der linksventrikuläre Spitzendruck fällt statt im Mittel um 30±11% (einfache Standardabweichung) um lediglich 23±12% gegenüber dem Ausgangswert ab, dP/dtmax statt um 31±15% um lediglich 20±10%. Im paarweisen Vergleich der Injektionsreaktionen mit und ohne zugesetztem Kalzium, zeigt sich der Unterschied als schwach signifikant (p〈0,05). Bei Verwendung des nichtionischen Metrizamids zeigen sich die kardiodepressiven Nebenwirkungen in noch geringerer Ausprägung. Die Druckminderung im linken Ventrikel beträgt hier nur 13±10%, die Kontraktilität fällt lediglich um 7±7% ab (bezogen auf einen mittleren Ausgangswert). Der Unterschied zu den Reaktionen unter Diatrizoat allein ist mitp〈0,001 hochsignifikant. Die unter Diatrizoat zum Teil ausgeprägte Frequenzverlangsamung zeigt sich unverändert auch bei Zusatz von Kalzium. Bei Verwendung von Metrizamid ist sie nur angedeutet. Bei der linksventrikulären Injektion zeigen sich deutliche Unterschiede in der Phase peripherer Vasodilatation. Während es hier unter Diatrizoat zu einem deutlichen Druckabfall kommt, ist dieser unter Metrizamid, dem Kontrastmittel mit wesentlich niedrigerer Osmolarität, kaum nachzuweisen (p〈0,001). Da unter Metrizamid die unerwünschten, kardialen Nebenwirkungen, wie Senkung des Perfusionsdrucks, gering sind, erweist es sich als besonders geeignet für die Untersuchung von Risikopatienten. Hinsichtlich seiner geringen Nebenwirkungsrate übertrifft es auch Diatrizoat in Kombination mit Kalzium.
    Notes: Summary Cardiodepressive side effects of angiocardiography can be reduced by using non-ionic metrizamide (Amipaque) or adding calcium to diatrizoate (Urografin 76%). In 15 patients with coronary artery disease undergoing heart catheterization, we compared cardiac side effects of coronary angiography and left ventricular angiography using metrizamide and diatrizoate with and without additional calcium (11,3 mmol/l) as contrast media under randomized conditions. In selective intracoronary injection with diatrizoate alone, peak left ventricular pressure and contractility (dP/dtmax) showed a fall of 30±11% and 31±15% (n=33 injections). Using diatrizoate with added calcium (11,3 mmol/l), the fall was only 23±12% and 20±10% respectively (n=31 injections). With metrizamide (n=32 injections) cardiac side effects are even less and the decrease in pressure and contractility only 13±10% and 7±7% respectively, which its highly significant (p〈0,001) compared with the effect of diatrizoate. The heartrate slowing, not essentially altered by calcium addition, was minimal using non-ionic metrizamide. In left ventricular angiography, the pressure fall in the late phase after injection of diatrizoate, caused by decreased peripheral vascular resistance (vasodilation), was lacking when injecting metrizamide (p〈0,001). Metrizamide has even less cardiodepressive side effects than diatrizoate with additional calcium when used in angiocardiography and seems to be suitable particularly for the evaluation of high risk patients.
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  • 2
    ISSN: 1432-1912
    Keywords: Cardiac metabolism ; Myocardial ischemia ; Oxfenicine ; Oxygen debt ; Oxygen repayment ; Release of electrolytes and substrates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Potential protective effects of oxfenicine [(S)-4-hydroxyphenylglycine] in ischemic stressed canine myocardium have been studied. This compound is characterized as a drug leading to metabolic inhibition of free fatty acid (FFA) metabolism. The drug (0.06 mmol·kg−1 body weight) caused no changes in hemodynamics or energy demand (Et) but depressed myocardial oxygen consumption (MVO2) by 11% (P〈0.02). Significant changes in FFA and lactate metabolism were observed: lactate extraction (EX) increased from 22.5–37.1 μmol/min, extraction ratio (EXR) from 16.5–30% and oxygen extraction ratio (OER) from 24.8–38%; EX of FFA decreased from 6900–5000 nmol/min, EXR from 48.2–31.4% and OER from 59.7–46.6%. Arterial concentrations of FFA and lactate remained unchanged. EX, EXR and OER of glucose were not affected under basic conditions. In the same collective, repeated ischemia (3 min) was produced by proximal occlusion of the left anterior descending artery (LAD). The efficiency of the drug was examined by (a) the amounts of ischemia metabolites released in the early reperfusion and (b) quantification of O2-debt and O2-repayment in the occlusion- and reperfusion periods. Compared to control occlusions, premedication led to a reduced O2-debt (P〈0.01) combined with a reduced amount of oxygen additionally taken up in the early reperfusion (P〈0.05). Furthermore, release of potassium increased (+7.1%; P〈0.05); release of lactate (-32%, P〈0.001) and inorganic phosphate (-34%, P〈0.01) decreased. These data give support to the concept that a pharmacologically induced shift of cardiac metabolism with reduction of FFA utilisation may be favourable in circumstances with limited oxygen supply.
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  • 3
    ISSN: 1432-1912
    Keywords: Cardiac metabolism ; Ischemia ; Isosorbide dinitrate ; Nicorandil ; Oxygen-debt ; Oxygen-repayment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This study was designed to investigate the effects of nicorandil in comparison to isosorbide dinitrate (ISDN) on hemodynamics, on myocardial metabolism and on effectiveness in the preservation of ischemically stressed myocardium. Repeated ischemia (3 min) was produced in anaesthetized open-chest mongrel dogs by proximal, intermittent left anterior descending artery occlusion with subsequent reperfusion. In each experiment 2–3 control occlusions were compared to 2–3 occlusions under nicorandil or ISDN. Application of both nicorandil (0.64 μmol·kg−1 body weight, i.v.) and ISDN (1.27 μmol·kg−1 body weight, i.v.) led to a significant afterload reduction and to a decrease of the coronary vascular resistance. The efficiency of the compounds in the protection of ischemic myocardium was examined by quantification of oxygen-debt and oxygen-repayment in the occlusion and reperfusion periods. Compared to control, premedication with nicorandil led to a significant increase of oxygen-debt, whereas ISDN reduced it significantly. Oxygen-repayment remained unchanged. The influence of the drugs on the metabolism of glucose, lactate and free fatty acids (FFA) was examined under basic conditions, in ischemia and during reperfusion. For all substrates, extraction, extraction ratio and oxygen extraction ratio were calculated. Under basic conditions, glucose metabolism was significantly enhanced in both groups but FFA metabolism was inhibited only by ISDN. In ischemia, FFA metabolism was enhanced by nicorandil and depressed by ISDN. Data obtained in this study suggest that nicorandil may even aggravate the metabolic and energetic situation of ischemic myocardium and, on the other hand, clearly support the well documented protective effects of ISDN.
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  • 4
    ISSN: 1432-2013
    Keywords: Inert gas dilution method ; Deconvolution ; Circulatory transport function ; Indicator transit time ; Heterogeneity of myocardial blood flow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Following single breath inhalations of helium 49 simultaneous inlet-outlet pairs of helium dilution curves were recorded in seven dog experiments from the aortic and coronary sinus blood by use of mass spectrometric technique. After numeric deconvolution of the dilution curves the weighting function of tracer transit times was used for calculation of the mean myocardial blood flow per unit of tissue, which closely correlated with directly measured flow. Secondly, the degree of blood flow heterogeneity was estimated from the first moments of the weighting function of transit times and by compartmental analysis based on an inverse Laplace transform. In the intact heart the results suggest a rather constant dispersion of flows relative to the mean flowFF in the order of σ/FF=0.3. The apparent dispersion of flows is increased by α-adrenergic stimulation with pressure and volume load, particularly in a state of β-blockade, a finding, which may be attributed to variations of intercapillary distances and to a heterogeneity of blood flow per unit of tissue.
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  • 5
    ISSN: 1433-8580
    Keywords: Ischemia ; Oxygen debt ; Oxygen repayment ; Release of metabolic ischemia indicators ; Thromboxane synthetase inhibitor ; UK 38.485
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This study was performed to examine potential protective effects of UK 38.485, an inhibitor of thromboxane synthetase, in canine myocardium stressed by transient ischemia. On anesthetized open-chest mongrel-dogs (n = 9) repeated ischemia (3 min) was produced by proximal, intermittent occlusion of the left anterior descending artery. A total of 18 occlusions after 3 mg UK 38.485/kg body wt. and 12 occlusions after 5 mg UK 38.485/kg body wt. were compared to a total of 24 occlusions under control conditions. In each experiment, 2–3 control occlusions and 3–4 therapy occlusions were performed. The drug was applied i.v. in a dose of 3 or 5 mg/body wt. 30 min before the first therapy occlusion. In both groups, hemodynamics and energetics did not significantly change as compared to control. The efficiency of the drug in protecting ischemically stressed myocardium was examined by (a) quantification of oxygen debt and oxygen repayment in the occlusion and reperfusion periods and (b) the amounts of inorganic phosphate, lactate, and potassium released in the first minute of reperfusion. Compared to control occlusions, premedication with either 3 or 5 mg UK 38.485 led to a significantly reduced oxygen debt combined with a significant decrease of the release of inorganic phosphate, lactate, and potassium. The protective effect is suggested to be mainly due to enhanced flow to ischemic areas. Data obtained in this study suggest protective effects of the compound in the preservation of myocardium in transient ischemia and attest to the concept that thromboxane A2 may aggravate the metabolic and energetic situation of myocardium in circumstances with reduced oxygen supply.
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  • 6
    ISSN: 1435-1803
    Keywords: myocardial oxygen consumption ; coronary occlusion ; reperfusion ; quantification ; ischemic area
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In 9 open-chest mongrel dogs 4–6 intermittent 3-min occlusions of the LAD artery were performed with time intervals of about 45 min. Using a μ-computer, the following variables, were calculated online: energy demand according to the Bretschneider equation (Et) from digitized hemodynamic data; myocardial oxygen consumption (M $$\dot V$$ O2) from fiberoptically measured coronary sinus oxygen saturation and coronary sinus blood flow. Coronary occlusion led to a decrease in M $$\dot V$$ O2 in comparison to Et. The integral of the difference between M $$\dot V$$ 2 and E1 over the entire occlusion time yielded a total O2-deficiency (DO2) of 76 (±12%) μl O2/g ischemic tissue and a correlation coefficient with the weights of the intravitally stained ischemic areas of r=0.96. Additional O2-uptake in relation to Et during the early perfusion period yielded a correlation to the size of the ischemic area of r=0.95 and an average O2-repayment (RO2) of 32 (±14%) μl O2/g ischemic tissue. The determination of total myocardial O2-deficiency during ischemic stress as well as determination of O2-repayment during the early reperfusion period could be used to estimate the extent of ischemic stressed myocardium. Subsequently, the evaluation of pharmacological effects on myocardial ischemia should be possible.
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  • 7
    ISSN: 1435-1803
    Keywords: ischemic stress ; oxygen debt ; release of substrates and electrolytes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary As criterion for the degree of ischemic stress on myocardium during repeated cronary artery occlusion, the reproducibility of the release of potassium, lactate and inorganic phosphate in the early reperfusion period was examined. On 20 anaesthetized open-chest mongrel-dogs, local ischemia was induced by intermittent occlusion of the LAD artery. In each experiment the artery was occluded for 3 min 4 to 6 times with intervals of 45 min. Just before beginning, at the end of occlusion and after 5 min of reperfusion, arterial and coronary venous blood was collected simultaneously. Additionally, 3 ml of blood were withdrawn by syringe-pumps during the first minute of reperfusion. Intraindividually, the following standard-deviations were found in a representative experiment with 5 occlusions: potassium ±7% (22.62±1.6 μmol/min); inorganic phosphate ±9% (19.82±2.06 μmol/min); lactate ±11% (55.38±5.93 μmol/min). Interindividually, the correlation between the release of these markers and the perfusion bed of the ligated artery led to coefficients of about r∼0.88. On an average, per gram ischemic tissue/wet weight 0.74 μmol potassium, 0.6 μmol inorganic phosphate and 1.98 μmol lactate were released. The ratios between the releases remained constant independent of the size of ischemic area. An even closer correlation with coefficients of about r∼0.97 was found between the releases and the O2-debt in the occlusion period. Based on a synoptic assessment of metabolic and energetic parameters, this experimental model may render more detailed information on pharmacological interventions during ischemic stress.
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  • 8
    ISSN: 1435-1803
    Keywords: myocardial oxygen consumption ; myocardial energy demand (Et) ; left ventricular diastolic tone ; left ventricular diastolic wall tension ; left ventricular diastolic pressure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A marked increase in left ventricular diastolic pressure $$(\bar P_{LVD} )$$ relative to volume is regularly observed during angina pectoris and may contribute to further deteriorations of myocardial perfusion in the ischemic myocardium and to pulmonary congestion as well. A possible simultaneous increase in myocardial oxygen consumption (MVO2) due to a reversible diastolic tone during transient ischemia has not been taken into consideration in previous studies on alterations in ventricular diastolic properties. 13 closed-chest experiments were carried out in clinical catheterization technique with situations of high $$(M\dot VO_2 )$$ (18–50 mm Hg) relative to volume induced by right ventricular pacing (n=19; 172±5 beats/min) and catecholamine-induced reversible diastolic tone (n=17) in moderate hypothermia (31°C). $$\bar P_{LVD} $$ was directly measured and indirectly calculated from its hemodynamic determinants using Bretschneider's equation (Et) that does not consider ventricular diastolic pressure. In addition, an energy demand for maintenance of active diastolic wall tension (E5) was calculated from $$M\dot VO_2 $$ mean ventricular diastolic volume estimated from endsystolic and stroke volume, diastolic time and heart rate in ml O2/min·100g. During pacing tachycardia with high $$\bar P_{LVD} $$ (27.4±1.8 mm Hg) the $$\bar P_{LVD} $$ (12.49±0.50 ml O2/min·100 g) exceeds Et (10.11±0.25 ml O2/min·100 g) (p〈0.001), partly due to neglect of E5 (1.39±0.11 ml O2/min·100 g). During catecholamine-induced high $$M\dot VO_2 $$ (31.1±2.5 mm Hg) the $$\bar P_{LVD} $$ (12.29±0.83 ml O2/min·100 g) increases significantly (p〈0.001) over Et (10.43±0.81 ml O2/min ·100 g). Addition of E5 (1.76±0.14 ml O2/min·100g) to Et abolishes the differences between $$M\dot VO_2 $$ and Et yielding non-significantly different values. Results indicate by means of indirect energetic evidence the occurrence of a diastolic tone of the heart under unphysiologic conditions. Acute increases in $$\bar P_{LVD} $$ during angina pectoris are supposed to increase $$M\dot VO_2 $$ markedly due to an additional energy demand for maintenance of reversible active diastolic wall tension.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Basic research in cardiology 76 (1981), S. 115-123 
    ISSN: 1435-1803
    Keywords: myocardial oxygen consumption ; myocardial energy demand ; myocardial pumping efficiency ; unhomogeneous contraction ; active diastolic wall tension ; atrial pacing ; oxygen saving effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die Auswirkungen von Ventrikelstimulation (90–330/min) und Vorhofstimulation (120–210/min) auf den myokardialen O2-Verbrauch, seine hämodynamischen Determinanten und den Wirkungsgrad der Pumpfunktion wurden systematisch untersucht. An sechs intakten Hunden wurden 158 Steady-states ausgewertet. Die simultane Messung des myokardialen O2-Verbrauchs (5–30 ml/min·100 g) erfolgte direkt aus Koronardurchblutung (Druckdifferenzkatheter) und O2-Gehaltsdifferenz und indirekt nach der hämodynamischen Formel Eg=E0+E1+E2+E3+E4. Die Effekte von Vorhof- und Ventrikelstimulation wurden innerhalb eines Versuches jeweils bei identischen Herzfrequenzen verglichen. Zusätzlich erfolgte im Kontrollkollektiv eine physiologische Variation der Herzfrequenz und des O2-Verbrauchs durch Katecholamine und Atropin. Ventrikelstimulation führte mit steigender Schrittmacherfrequenz trotz reduzierter Hämodynamik zu einem überproportional ansteigenden O2-Verbrauch des Herzens, bezogen auf die hämodynamischen Determinanten bis zu 50%. Der Wirkungsgrad der Pumpfunktion nahm bei steigender Herzfrequenz konsekutiv deutlich ab. Das Herzzeitvolumen blieb beim suffizienten Herzen über einen weiten Frequenzbereich konstant. Vorhofstimulation zeigte dagegen günstige Effekte auf alle Parameter. Der O2-Verbrauch wurde, bezogen auf die hämodynamischen Determinanten, bis zu 25% gesenkt, bezogen auf Ventrikelstimulation sogar bis zu 60% bei deutlich besserer Hämodynamik. Die möglichen myokardialen, hämodynamischen und metabolischen Ursachen für die energetische Schere zwischen physiologischer und unphysiologischer Erregungsform des Herzens werden diskutiert.
    Notes: Summary The effects of ventricular pacing (90–330 beats/min) and atrial pacing (120–210 beats/min) on myocardial oxygen consumption $$(M\dot VO_2 )$$ and its hemodynamic determinants and on myocardial pumping efficiency were studied systematically on intact dogs. In six closed-chest experiments 158 steady states were analyzed. Myocardial blood flow was measured with a differential pressure sinus catheter, oxygen consumption (5–30 ml/min·100 g) was determined simultaneously by the Fick principle and the additive hemodynamic parameter Et. Ventricular and atrial pacing were compared with both methods at identical heart rates. Additionally, the coincidence between both methods of determining $$M\dot VO_2 $$ overproportionally up to 50% in sinus rhythm with sympathetic stimulation (norepinephrine, atropine) within each experiment. Ventricular pacing increased $$M\dot VO_2 $$ overproportionally up to 50% in relation to the hemodynamic determinants. Consequently, myocardial pumping efficiency markedly decreased with increasing ventricular rate. The close relation between directly measured $$M\dot VO_2 $$ and Et, found in previous studies, was maintained under sympathetic stimulation. Atrial pacing, as compared to ventricular pacing at identical rates, resulted in a decrease of $$M\dot VO_2 $$ up to 25% although the expected $$m\dot VO_2 $$ according to its hemodynamic determinants rather increased. The hemodynamic and metabolic mechanisms probably responsible for the energetic difference between ventricular and atrial pacing at equal heart rates are discussed.
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  • 10
    Publication Date: 2020-03-06
    Language: English
    Type: article , doc-type:article
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