The concept of an anatomy related individual arterial access: lowering technical and clinical complications with transradial access in bovine- and type-III aortic arch carotid artery stenting.

BACKGROUND: Carotid artery stenting (CAS) from the femoral approach can be anatomically very difficult and the incidence of complications is higher in patients with anatomical variations of the aortic arch, difficulties related to peripheral vascular disease and/or with access site complications. Because the typical morphology in patients with a bovine- or type-III aortic arch applies for an arterial access from the right upper extremity (e.g. radial, brachial) we evaluated success rates and safety of the right transradial access in a prospective study. PATIENTS AND METHODS: Between June 2009 and October 2010, seventeen patients (mean age 74,4 ± 9 years, 10 male) with a bovine- (n = 4) or type-III aortic arch (n = 12) underwent CAS with a planned transradial- (n = 3) or after problematic transfemoral access (n = 14). In patients with a type-III aortic arch (n = 13), the right target common carotid artery (CCA) was cannulated from the right radial artery with a 5F IMA diagnostic catheter-, in patients with a bovine aortic arch (n = 4), the left CCA was accessed from the right radial artery with a 5F Amplatz- or Judkins left catheter. In all patients a 6F- (n = 14) or 5F- (n = 3) shuttle sheath was inserted via the diagnostic catheter and a 0.035” extra-stiff guidewire. All interventions were carried out with the use of a peripheral embolization protection device (EPD). Primary study endpoints were procedural success and major adverse cardiac and cerebrovascular events (MACCE), secondary endpoints were access site complications and the mean intervention time. RESULTS: Procedural success could be achieved in all patients (100 %), MACCE and access site complications did not occur in any patient. Mean interventional time was 48 ± 18 min. CONCLUSIONS: CAS using the right transradial approach for left CAS in bovine-type aortic arch or the right transradial approach in type-III aortic arch for right CAS appears to be safe and technically feasible.

Transradial access in percutaneous coronary interventions: technique and procedure.

After showing significantly lower complication rates in diagnostic coronary angiography, the radial artery access was successfully introduced as a useful vascular access site for transradial percutaneous coronary intervention in order to enhance patients' comfort and reduce hospital workload and costs. Moreover, due to the reduced need for antiplatelet therapy cessation as a result of lower bleeding complications, patients treated with transradial access showed a significantly better cardiac outcome in randomized interventional acute coronary syndrome studies.Procedural success and postprocedural radial arteritis or radial occlusions are closely related to anatomical circumstances (e.g., anomalous radial branching patterns, tortuosity, e.g., radial loops and small radial artery diameters), or risk factors for radial spasms (e.g. smoking, anxiety, vessel diameter, age, gender) which can effectively be reduced by the use of smaller catheters (4-5 Fr) and the administration of an adjuvant pharmacological therapy before (3000 U heparin, verapamil, nitroglycerine) and after (ibuprofen) the intervention.For successful radial sheath access and transradial catheterization, it is important to use dedicated radial access needles ≤ 21-gauge and steel wires ≤ 0.018 in. In order to pass the brachiocephalic trunk without difficulties or complications and access the ascending aorta, the use of inspiration maneuvers is of central importance.

A kinetic model for cardiac PET with [1-carbon-11]-acetate.

UNLABELLED: Carbon-11-labeled acetate is a unique tracer for noninvasive assessment of myocardial oxidative metabolism with PET. Because adequate kinetic models have been missing, data evaluation in the past was performed mostly with phenomenological approaches such as mono- or biexponential fitting which cannot account for the influence of finite input duration and blood volume encountered in noninvasive PET investigations. METHODS: To investigate to what extent the current data evaluation schemes are justified, we developed a comprehensive model of [1-11C]-acetate kinetics in the myocardium which incorporates five tissue compartments: free acetate, activated acetate, CO2 precursors, amino acids and CO2. We derived the analytical solution of the model equations which is used for simulations and data fitting. RESULTS: The five-compartment model can reproduce in detail known experimental data. The resulting values of the eight model parameters compare favorably with existing biochemical facts. We have established the relation between parameters of the detailed model and one- and two-compartment models used for the evaluation of PET investigations. CONCLUSION: The kinetics of [1-11C]-acetate are adequately described by a five-compartment model. One- and two-compartment models are sufficient for simultaneous quantitative assessment of myocardial oxidative metabolism and perfusion with [1-11C]-acetate and PET.

Effect of carbon-11-acetate recirculation on estimates of myocardial oxygen consumption by PET.

Mono- and biexponential fitting of myocardial 11C-acetate kinetics does not account for the effect of recirculating 11C activity following intravenous injection of the tracer. A tracer kinetic model comprising two and three compartments was developed to describe intravascular and myocardial 11C-acetate kinetics defined by PET. This model approach including a correction for 11C-metabolites in blood was validated by correlating the model parameter estimates with directly measured oxygen consumption (MVO2) in 11 closed-chest dog experiments over a wide range of cardiac work. The model parameter k2 closely correlated with oxygen consumption (r = 0.94). This approach was subsequently applied to human studies and k2-related to rate-pressure product (PRP). In comparison to conventional monoexponential fitting of 11C-acetate tissue kinetics, the model approach improved the correlation coefficients of scintigraphic MVO2 estimates and PRP values from 0.61 to 0.91. Thus, analysis of myocardial 11C-acetate and clearance kinetics with a tracer kinetic model corrects for recirculating 11C-activity and may provide more consistent estimates of myocardial oxygen consumption.

[1-(11)C]Acetate as a quantitative perfusion tracer in myocardial PET.

UNLABELLED: Our objective was to investigate the properties of [1-(11)C]acetate as a quantitative perfusion tracer for myocardial PET studies. METHODS: We determined the flow dependence of the effective acetate extraction by a comparison with [(13)N]ammonia in 24 patients at rest (n = 8) and under pharmacologic vasodilation (n = 16). Furthermore, we compared the statistical quality of the perfusion values derived with both tracers. Quantification was based on an irreversible 2-compartment model for [(13)N]ammonia and a reversible 1-compartment model for [1-(11)C]acetate. Area-conserving polar maps were used to determine the correlation between the unidirectional uptake parameters of both tracers on a pixel-by-pixel basis for the whole left ventricular myocardium. RESULTS: A fit of a generalized Renkin-Crone formula to the data yielded the unidirectional acetate extraction fraction E(f) = 1 - 0.64e(-1.20/f). An extraction correction based on this formula led to good quantitative agreement of perfusion values derived with [(13)N]ammonia and [1-(11)C]acetate over the whole observed flow range (average difference of flow values, 3%; correlation coefficient, 0.96). This agreement proved the applicability of acetate as a quantitative perfusion tracer even under stress conditions. An analysis of the statistical properties of the parameter estimates showed, moreover, that statistical errors were reduced by a factor of nearly 2 in comparison with ammonia. CONCLUSION: [1-(11)C]acetate allows accurate quantification of myocardial perfusion with PET at rest as well as under stress conditions. The use of acetate leads to distinctly improved statistical accuracy for the perfusion estimates in comparison with ammonia. This accuracy facilitates the generation of reliable parametric polar maps, which are especially useful for clinical application of myocardial perfusion quantification.

The effect of ion composition on cellular membrane potentials during selective coronary arteriography.

An animal experimental study on seven thoracotomized dogs was designed to investigate the effects of intracoronarily injected sodium meglumine diatrizoate on myocardial electrophysiology and to evaluate the contribution of the corresponding changes of electrolyte levels in coronary blood. For this purpose the effects of alterations in the Na+-, K+- and Ca++-concentrations in coronary blood were studied separately by intracoronarily injected model solutions. Membrane potentials were recorded from the left ventricular myocardium by a modified microelectrode technique which is applicable to the beating and blood perfused heart in situ. Following selective coronary arteriography there was a temporary hyperpolarization of resting potentials and a prolongation of action potentials which may be explained by a contrast-induced local deficiency of potassium and calcium ions and by a relative prevalence of sodium ions in coronary blood. In selective coronary arteriography the synchronicity of cardiac excitation is disturbed by the regional prolongation of action potentials, which may induce ventricular arrhythmias.

Thermal recovery after passage of the pulmonary circulation assessed by deconvolution.

For indicator-dilution studies, complete thermal recovery after passage of heat through the pulmonary circulation would be desirable. However, the results in the literature obtained by extrapolation techniques are inconsistent. To overcome problems of the extrapolation approach, transport functions of the pulmonary circulation (including the left heart) were computed by deconvolution of pulmonary arterial and aortic pairs of thermodilution curves after central venous indicator injection (10 ml of an ice-cold blood indocyanine green dye mixture). Thermal recovery was determined as the finite integral of the transport function. Thirteen mongrel dogs under piritramid-N2O anesthesia were examined under base-line conditions, in orthostasis to alter the distribution of pulmonary blood flow (9 dogs), and in oleic acid edema (8 dogs). Using the deconvolution approach, thermal recovery was 0.97 +/- 0.04 under base-line conditions, 0.96 +/- 0.03 in orthostasis, and 0.96 +/- 0.05 in pulmonary edema. Thermal recovery determined from extrapolated dilution curves was greater than 100% in all groups, a physically impossible finding. It is concluded that thermal recovery is incomplete but insensitive with respect to the distribution of blood flow and to the size of the extravascular compartment. Monoexponential extrapolation is unsuited for the determination of thermal recovery.

Posttraumatic myocardial infarction with severe coronary intimal dissection documented by intravascular ultrasound.

We present a case of posttraumatic myocardial infarction after blunt chest trauma in a previously healthy man. Coronary angiography showed an eccentric occlusion in the midportion of the left anterior descending artery. Subsequent intracoronary ultrasound imaging revealed a severe intimal dissection. The outcome after intracoronary stent placement was excellent. This rare but potentially harmful complication of blunt chest trauma should be kept in mind and coronary angiography performed immediately when coronary occlusion is suspected. Intravascular ultrasound imaging is a helpful tool in the assessment of coronary artery occlusion caused by intimal dissection.

Changes in myocardial substrate utilisation and protection of ischemic stressed myocardium by oxfenicine [(S)-4-hydroxyphenylglycine].

Potential protective effects of oxfenicine [(S)-4-hydoxyphenylglycine] 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 less than 0.02). Significant changes in FFA and lactate metabolism were observed: lactate extraction (EX) increased from 22.5-37.1 mumol/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 less than 0.01) combined with a reduced amount of oxygen additionally taken up in the early reperfusion (P less than 0.05). Furthermore, release of potassium increased (+7.1%; P less than 0.05); release of lactate (-32%, P less than 0.001) and inorganic phosphate (-34%, P less than 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.

Effectiveness of nicorandil in the preservation of myocardium stressed by transient ischemia and its influence on cardiac metabolism during coronary artery occlusion with subsequent reperfusion: a comparison with isosorbide dinitrate.

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 mumol X kg-1 body weight, i.v.) and ISDN (1.27 mumol X 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.(ABSTRACT TRUNCATED AT 250 WORDS)

[Renal sympathetic denervation--physical-antomical basics, procedure, and analysis of clinical and technical parameters on procedure success and efficacy]. / Renale sympathische Denervierung: physikalisch-anatomische Grundlagen, technisches Vorgehen und Analyse klinischer und technischer Einflussgrößen auf die Effizienz der Hochfrequenzablation.

BACKGROUND: Evidence from human and animal models indicate that excessive central sympathetic nerve activity (SNA) plays a pathogenic role in triggering and sustaining hypertension. Thus, treatments targeting this neurogenic (sympathetic) triggered hypertension were evaluated and renal sympathetic denervation (RND) showed promising results. However, little is known about the parameters influencing efficacy of high frequency energy in the arterial model. PATIENTS AND METHODS: Data from all 40 consecutive patients suffering from therapy-resistant hypertension who underwent RND and completed a 1-year follow-up were retrospectively analyzed. We focussed on procedural success, complications and efficacy (office-blood pressure, 24-h-blood pressure) and its correlations to quantity of ablations and intima media thickness. RESULTS: In all patients (65.9 ± 11.6 years (range 42-83); 72.5% male) the procedure was successful. Ablations with arterial access from the upper extremity were technically unsuccessful. With the use of 13.6 ± 1.7 (10-17) ablations, office-blood pressure (1-year) could be reduced from 162/89 mmHg to 142/82 mmHg and 24-h-blood pressure from 149/83 mmHg to 139/79 mmHg, respectively, including a medium to strong correlation to quantity of ablations (r = 0.57, r = 0.63) while documenting only a weak correlation to IMT (r = -0.29, r = -0.25). CONCLUSION: In comparison to the Simplicity studies, the hypertension lowering effects were less profound but consistently present over time in the 24-h-blood pressure assessments. The positive correlation of the quantity of ablations we found seems to be plausible regarding the unpredictable allocations of the sympathetic nerves i.e. in profoundly kinking vessels in hypertensives. The physics of high-frequency energy application in the arterial model needs further research.

Estimation of myocardial blood flow heterogeneity by transorgan helium transport functions.

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 flow F in the order of sigma/F = 0.3. The apparent dispersion of flows is increased by alpha-adrenergic stimulation with pressure and volume load, particularly in a state of beta-blockade, a finding, which may be attributed to variations of intercapillary distances and to a heterogeneity of blood flow per unit of tissue.

Quantification of ischemic stress during repeated coronary artery occlusion in the dog. A method for validation of therapeutic effects. I. Estimation of O2-debt and O2-repayment.

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 mu-computer, the following variables were calculated online: energy demand according to the Bretschneider equation (Et) from digitized hemodynamic data; myocardial oxygen consumption (MVO2) from fiberoptically measured coronary sinus oxygen saturation and coronary sinus blood flow. Coronary occlusion led to a decrease in MVO2 in comparison to Et. The integral of the difference between MVO2 and Et over the entire occlusion time yielded a total O2-deficiency (DO2) of 76 (+/- 12%) microliter 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%) microliter 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.

Quantification of ischemic stress during repeated coronary artery occlusion in the dog. A method for validation of therapeutic effects. II. Reproducibility of the release and uptake of electrolytes and substrates.

As criterion for the degree of ischemic stress on myocardium during repeated coronary 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. Intra-individually, the following standard-deviations were found in a representative experiment with 5 occlusions: potassium +/- 7% (22.62 +/- 1.6 mumol/min); inorganic phosphate +/- 9% (19.82 +/- 2.06 mumol/min); lactate +/- 11% (55.38 +/- 5.93 mumol/min). Interindividually, the correlation between the release of these markers and the perfusion bed of the ligated artery led to coefficients of about r approximately 0.88. On an average, per gram ischemic tissue/wet weight 0.74 mumol potassium, 0.6 mumol inorganic phosphate and 1.98 mumol 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 approximately 0.97 was found between 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.

[Comparison of the acute cardiovascular side effects of iopamidol, metrizamide and amidotrizoate after intracoronary and left ventricular injections]. / Vergleich der akuten kardiovaskulären Nebenwirkungen von Iopamidol, Metrizamid und Amidotrizoat bei intrakoronarer und linksventrikulärer Injektion.

The acute cardiovascular side effects of iopamidol (osmolality: 0.8 osmol/kg), metrizamide (0.6 osmol/kg), and amidotrizoate (2.1 osmol/kg) during coronary arteriography (n = 30) and left ventriculography (n = 9) have been compared in anesthetized closed-chest dogs (n = 5). The influences of these contrast media on hemodynamics, coronary circulation, ECG and physicochemical properties of coronary sinus blood were evaluated. Following intracoronary injection, iopamidol and metrizamide cause positive inotropism while amidotrizoate initially induces cardiodepression. All contrast solutions lead to marked increase of myocardial blood flow. Electrocardiographic changes are greater after amidotrizoate (P less than 0.05). A fall of cationic content in coronary sinus blood is seen after each contrast medium. Amidotrizoate leads to more decrease of potassium (P less than 0.01) and both ionized and total calcium (P less than 0.001). Increase of osmolality and hydrogen ionic content is greater after amidotrizoate than after iopamidol and metrizamide (P less than 0.01). Following left ventricular injection, marked peripheral vasodilation, as seen after amidotrizoate, does not occur after low osmolality compounds. There are no significant differences between iopamidol and metrizamide in spite of the slightly higher osmolality of the former. Thus, both contrast materials should be equivalent with respect to their acute cardiovascular side effects under clinical conditions. Advantages of low osmolality radiological contrast media are discussed.

Heterogeneity of myocardial blood flow under normal conditions and its dependence on arterial PO2.

We studied the heterogeneity of myocardial blood flow in nine anesthetized closed-chest dogs using an indicator-dilution technique that allows the stochastic description of transport characteristics for three inert gases (helium, argon, and xenon) from the coronary inflow to outflow. The results show that under normal conditions the transcoronary transport of the tracers is spatially heterogeneous. Heterogeneity is strongly dependent on the arterial oxygen tension over a range of 40-200 Torr. This could be similarly observed with each tracer gas despite different physicochemical properties and was largely independent from the magnitude of coronary blood flow. The results are interpreted to mean that the arteriolar or intratissue PO2 influences myocardial blood flow over a broad range and possibly acts as an important integrating factor in the local regulation of coronary blood flow and flow reserve.

Comparison of the effects of right atrial, right ventricular apex and atrioventricular sequential pacing on myocardial oxygen consumption and cardiac efficiency: a laboratory investigation.

As the impact of cardiac pacing on myocardial energetics has not yet been established, this laboratory investigation was undertaken to evaluate the effects of right atrial (AP), right ventricular apex (VP) and atrioventricular sequential pacing (AVP) on cardiac energetics in a closed-chest model. Ninety-two pacing interventions were performed in ten anesthetized mongrel dogs with normal loading conditions and contractile states. The energetic effects of pacing were assessed in terms of myocardial oxygen consumption (MVO2), its hemodynamic determinants and cardiac efficiency. Efficiency was calculated as the ratio of O2-equivalent of external cardiac work to MVO2, using standard definitions. In the first series of experiments 36 intra-individual comparisons were made between AP and VP at identical rates (95-210 beats/min). In the second series AVP was compared to VP in 10 intra-individual comparisons at identical rates (109-190 beats/min). MVO2 was lower (p less than 0.001) during AP (8.30 +/- 2.14 ml O2/min.100 g) compared to VP (10.16 +/- 3.15 ml O2/min.100 g) at the same rate (158 +/- 32 beats/min). Efficiency (p less than 0.001) was considerably higher during AP (21.6 +/- 5.7%) compared to VP (12.8 +/- 5.9%). During AVP, MVO2 (10.85 +/- 1.76 ml O2/min.100 g) was not significantly different from VP (10.57 +/- 1.34 ml O2/min.100 g) at the same rate (146 +/- 25 beats/min). Hemodynamics were superior with AVP compared to VP. Efficiency was significantly higher (p less than 0.01) with sequential (15.4 +/- 3.9%) as compared to ventricular pacing (12.0 +/- 3.2%). In conclusion, this study indicated that VP exerts disadvantageous effects on MVO2 and cardiac efficiency. AP has beneficial effects on cardiac energetics because it improves the relationship between mechanical performance of the heart and its energy requirements. AVP results in a higher efficiency than VP due to superior hemodynamics, despite MVO2 levels comparable to those of VP. The mechanism of energy waste with right ventricular apex pacing is probably related to an asynchronous contraction in the ventricular myocardium due to a nonphysiological spread of excitation.