Intravenous Injection Of Adenosine Research Articles

Abstract 9764: Simultaneous Assessment of Coronary Flow Reserve and Left Ventricular Strain During Vasodilator Stress Measured by 13 N-ammonia Positron Emission Tomography/Magnetic Resonance Imaging

Introduction: Hybrid positron emission tomography (PET)/magnetic resonance imaging (MRI) is able to yield important information regarding molecular and functional imaging in a one-stop examination. The aim of this study was to investigate the relationship between coronary flow reserve (CFR) and left ventricular longitudinal strain (LVLS) using simultaneous acquisitions on hybrid 13 N-ammonia PET/MRI. Methods: Thirty-eight patients with suspected coronary artery disease (CAD) who underwent 13 N-ammonia PET/MRI were enrolled. Vasodilator stress was induced by intravenous injection of adenosine. CFR was calculated from dynamic acquisition of 13 N-ammonia PET. LVLS was evaluated by feature-tracked MRI. Myocardial flow reserve (MFR) and LVLS values were based on a 17-segment model and three coronary territories, left anterior descending artery (LAD), left circumflex artery (LCx), and right coronary artery (RCA). Results: We analyzed 577 myocardial segments in the left ventricle. LVLS under vasodilator stress was significantly increased compared with LVLS at rest in myocardial segments with MFR ≥2.0 (P<0.01), whereas there were no changes between LVLS under stress and LVLS at rest in the segments with MFR < 2.0 (P=0.24). Similarly, regional values of LVLS under vasodilator stress were significantly increased compared with those measured at rest in the coronary territories of LAD (P<0.01), LCx (P<0.01), and RCA (P<0.01) with MFR ≥ 2.0, whereas there were no differences between LVLS at rest and LVLS under stress in those territories with CFR < 2.0 (P=0.45). These data revealed that left ventricular strain under vasodilator stress was impaired in segments with lower CFR. Conclusion: Simultaneous assessment of regional CFR and LV strain was feasible using by 13 N-ammonia PET/MRI. 13 N-ammonia PET/MRI was able to detect not only impaired CFR but also morphological abnormalities, which may improve diagnostic and predictive capacity in patients with CAD.

Abstract 9916: Prognostic Value of Simultaneous Analysis With Myocardial Flow Reserve and Right Ventricular Strain by Hybrid 13 N-ammonia Positron Emission Tomography/Magnetic Resonance Imaging in Coronary Artery Disease

Introduction: Myocardial flow reserve (MFR) derived from 13 N-ammonia positron emission tomography (PET) is used to predict adverse cardiac events in the patients with coronary artery disease (CAD). Right ventricular (RV) strain measured by magnetic resonance imaging (MRI) is used to evaluate RV function. This study aimed to evaluate the prognostic value of combined MFR and RV strain measured by hybrid 13 N-ammonia PET/MRI in patients with CAD. Methods: Sixty-one patients who underwent 13 N-ammonia PET/MRI were enrolled. MFR was calculated from dynamic acquisition of 13 N-ammonia PET under vasodilator stress with intravenous injection of adenosine. RV global longitudinal strain (GLS) was measured by wall motion tracking techniques in cine-mode MRI. The end points were defined as a composite of all-cause death, myocardial infarction, sustained ventricular arrhythmia, hospitalization due to decompensated heart failure, and revascularization. Results: At a follow-up of 2.8 ± 1.9 years, 21 events occurred. Kaplan-Meier analysis showed that the event-free rate was significantly lower in the group with MFR < 1.80 than that with MFR ≥ 1.80 (P < 0.001, Figure a). Additionally, the event-free rate was significantly lower in the group with RVGLS > –18.22% than that with RVGLS ≤ –18.22% (P = 0.025, Figure b). After dividing the patients into four groups by the median MFR and the median RVGLS, the event-free rate was lowest in the combined group of MFR < 1.80 and RVGLS > -18.22% than any other groups (P < 0.001, Figure c). In the Cox proportional hazard analysis, MFR and RVGLS were independent predictors of cardiac adverse events in the patients with CAD. Conclusion: The simultaneous assessment of MFR and RV strain by 13 N-ammonia PET/MRI revealed the feasibility of precise risk stratification for cardiac events in patients with CAD.

Abstract 12890: Prognostic Value of Relative Flow Reserve by Hybrid 13 N-ammonia Positron Emission Tomography/Magnetic Resonance Imaging in Coronary Artery Disease

Background: 13 N-ammonia PET has been used to evaluate myocardial blood flow (MBF) and coronary flow reserve (CFR) quantitatively. Relative flow reserve (RFR) was defined as the ratio of hyperemic MBF in a stenotic area to hyperemic MBF in a normal perfused area. The aim of this study was to examine the prognostic value of RFR in patients with coronary artery disease (CAD). Methods: We enrolled consecutive 66 patients with suspected CAD who underwent hybrid 13 N-ammonia PET/MRI. Under vasodilator stress with intravenous injection of adenosine, MBF and CFR were calculated from dynamic acquisition of 13 N-ammonia PET. RFR was calculated as the ratio of hyperemic MBF of a stenotic myocardial area to hyperemic MBF of a non-stenotic reference vascular territory. MRI images were simultaneously acquired with PET. Left ventricular ejection fraction (LVEF) was calculated from cine mode MRI. The end points were defined as composite of all-cause death, sustained ventricular arrhythmia, hospitalization due to decompensated heart failure and coronary artery revascularization. Results: Over the median follow-up of 3.6 ± 1.3 years, there were 22 (33.3%) adverse cardiac events. Kaplan-Meier analysis demonstrated lower event free rates in patients with CFR < 2.0 (P < 0.01, Figure A) and RFR < 0.81 (P = 0.022, Figure B), but not in those with stress MBF < 1.34 (P = 0.295) and stress LVEF < 55% (P = 0.187). Univariate Cox regression analysis showed that abnormal RFR (< 0.81) was significantly associated with adverse events (HR 3.72, 95% CI 1.21-18.01, P = 0.02). Conclusion: RFR is a useful marker to predict cardiac adverse events in patients with CAD. It would be an alternative approach to perform only stress scan without rest scan to reduce radiation exposure and scan time.

Simultaneous assessment of coronary flow reserve and left ventricular function during vasodilator stress evaluated by 13N-ammonia hybrid PET/MRI

To explore changes in left ventricular (LV) function and the relationship of these changes with myocardial blood flow (MBF) evaluated by 13N-ammonia hybrid positron-emission tomography (PET)/magnetic resonance imaging (MRI) during vasodilator stress in patients with suspected coronary artery disease (CAD). Fifty-two consecutive patients with suspected CAD, who underwent 13N-ammonia PET/MRI, were enrolled. Vasodilator stress was induced by intravenous injection of adenosine. MBF and coronary flow reserve (CFR) were calculated from dynamic acquisition of 13N-ammonia PET. LV function was evaluated by MRI both at rest and during vasodilator stress. An abnormal perfusion on myocardial images was defined as a summed difference score of ≥4. MRI showed that the LV end-diastolic volume, LV end-systolic volume, and LV ejection fraction (LVEF) remained unchanged during vasodilator stress in all patients (n=52) as well as in the patients with CFR of <2 (n=27), stress MBF of <1.3 ml/g/min (n=28), abnormal myocardial perfusion (n=30), and more than one diseased vessel (n=46). In only four patients, the LVEF measured by MRI decreased by >5% during vasodilator stress. In these four patients, CFR was lower (1.57±0.12 versus 2.18±0.86, p<0.01) and the number of diseased vessels was higher (2.75±0.50 versus 1.48±0.92, p<0.01) than in patients without post-stress LV dysfunction. The LV volume and systolic function evaluated by cardiac MRI remained unchanged during vasodilator stress; however, LV dysfunction during vasodilator stress may occur in patients with severe CAD.

Reduction of AF Recurrence After Pulmonary Vein Isolation by Eliminating ATP‐Induced Transient Venous Re‐Conduction

Recent evidence has suggested that the transient re-conduction of the isolated pulmonary vein (PV) induced by the intravenous injection of adenosine (dormant PV conduction) might predict the incidence of subsequent venous reconnection after the procedure, which is the main cause of the atrial fibrillation (AF) recurrence after PV isolation (PVI). We tested the hypothesis that the elimination of these dormant PV conductions by additional radiofrequency (RF) applications can improve the efficacy of the PVI. One hundred forty-eight patients (124 males; mean age 53 +/- 9 years) with drug-refractory AF underwent the PVI procedure. The standard PVI was performed in 94 patients (Group A), whereas the elimination of adenosine triphosphate (ATP)-induced dormant conduction using additional RF energy was performed in addition to the standard PVI in other 54 patients (Group B). Dormant conduction was observed in 56% of the patients (30/54) in Group B and 95% of these transient re-conductions were successfully eliminated by additional RF applications (mean: 1.5 +/- 1.0 times). During the mean follow-up period of 20 months, recurrences of AF after the procedures were observed significantly less frequently in Group B (20%) than in Group A (40%) (P < 0.05). The use of additional RF applications to eliminate transient PV reconnection induced by ATP injection led to a reduction of AF recurrence after PVI, most likely due to the minimization of the subsequent PV reconnection.

Paroxysmal Supraventricular Tachycardia in a Patient with Wolff-Parkinson-White Syndrome Induced by Central Venous Cannulation and Surgical Stimuli during Operation: A case report

Wolff-Parkinson-White (WPW) syndrome is a cardiac conduction disorder that presents potentially life-threatening consequences, and it is important that anesthesiologists recognize this syndrome because the sudden development of tachyarrhythmias may result in deleterious hemodynamic changes. We report an episode of severe hemodynamic changes induced by the insertion of a guide wire during central venous cannulation and operation in a 62-yr-old female patient with WPW syndrome. Initially, unstable paroxysmal supraventricular tachycardia was developed during central venous cannulation, which was disappeared immediately upon removing the guide wire. Subsequently, paroxysmal supraventricular tachycardia with severe hemodynamic changes developed 2 hours after operation, and this was successfully treated with an intravenous injection of adenosine, deep anesthesia with sevoflurane and fentanyl, and dopamine infusion. The patient recovered uneventfully after the operation.

Stimulation of vagus nerve modifies negative chronotropic and hypotensive effects of adenosine.

The effects of electrical stimulation of the vagus nerve on the negative chronotropic and hypotensive effects of adenosine were studied on adult rats. Intravenous injection of adenosine to control rats significantly reduced the heart rate and induced a transient blood pressure drop followed its increase. Preliminary electrical stimulation of the right vagus nerve reduced the magnitude and duration of adenosine-induced bradycardia and changed the dynamics of adenosine-induced arterial pressure perturbations.

Influence of Beta-Adrenergic and Vagal Activity on the Effect of Exogenous Adenosine on Supraventricular Tachycardia Termination

Adenosine, which binds to cell surface receptors and couples with guanosine triphosphate-binding inhibitory proteins (Gi), is potent in terminating supraventricular tachycardia (SVT). However, whether the differences in autonomic tone will influence this effect remains unknown. This study was designed to investigate the role of β-adrenergic and vagal activity on the action of adenosine. Forty patients with clinically documented SVT (22 with atrioventricular node reentrant tachycardia and 18 with atrioventricular reciprocating tachycardia) were divided into 4 groups with 10 patients in each group. In groups 1 and 2, adenosine was intravenously injected during the baseline state and during infusion of isoproterenol (2 and 4 μg/min, respectively). Group 2 patients received atropine (0.04 mg/kg) injection before isoproterenol infusion. In groups 3 and 4, intravenous injection of adenosine was given during the baseline state and after injection of atropine (0.02 and 0.04 mg/kg, respectively). Group 4 patients received propranolol (0.2 mg/kg) before atropine injection. The minimal dose of adenosine to terminate tachycardia during isoproterenol infusion of 2 μg/min was greater than that during the baseline state in both groups 1 and 2. The minimal dose of adenosine during isoproterenol infusion with 4 μg/min was higher than that with 2 μg/min in group 2, but not in group 1 patients. In both groups 3 and 4, the minimal dose of adenosine required to terminate tachycardia during atropine injection with 0.02 mg/kg was greater than that during the baseline state. The minimal effective dose of adenosine during atropine injection with 0.04 mg/kg was higher than that with 0.02 mg/kg in group 4, but not in group 3 patients. In conclusion, either limb of the autonomic nervous system may modulate the adenosine dosage required for termination of SVT. Patients taking drugs such as β blockers or vagolytic agents may need alterations in the dose of adenosine for therapy.Infusion of isoproterenol or atropine increased the minimal effective dose of intravenous adenosine required for termination of supraventricular tachycardia. This suggested that differences in autonomic tone may influence the effects of adenosine.

Respiratory Response to Adenosine in Newborn Lambs Is Modified by Hypoxemia and by Heat Stress

A study was made to determine whether adenosine is involved in the regulation of breathing and whether the respiratory response to injections of adenosine and its analogue L-PIA (phenylisopropyl adenosine) is modified by moderate hypoxemia or by heat stress. Unanesthetized lambs with chronically implanted catheters were used for the investigation. Intravenous injections of adenosine caused an increase in the rate of breathing lasting for 5-30 s, except during heat stress, when the rate of breathing decreased. Injection of L-PIA also increased the rate of breathing, but the effects lasted longer than after injection of adenosine. During heat stress the response to injection of L-PIA varied. Both the arterial blood pressure and heart rate decreased transiently after intravenous injection of adenosine or L-PIA, while the central venous pressure increased. Adenosine might thus be part of a positive feedback system that stimulates breathing under normal environmental conditions with or without moderate hypoxemia. The respiratory responses to injection of adenosine during heat stress are different, which might indicate that under this condition the effects of adenosine on breathing are modified by its influence on temperature control.

Effect of ADP-induced platelet aggregation on lung fluid balance in sheep.

The effects of platelet aggregation (PA), induced by an intravenous injection of adenosine 5'-diphosphate (ADP), on pulmonary fluid and protein exchange and on arterial blood gases were determined in artificially ventilated sheep prepared with lung lymph fistulas. ADP injection produced small increases (P less than 0.01) in pulmonary lymph flow (Qlym) and transvascular protein clearance (Qlym X lymph-to-plasma protein concentration ratio). These changes were not associated with significant increases in pulmonary arterial and left atrial pressures, pulmonary blood flow, or pulmonary vascular resistance. ADP-induced PA did not increase the pulmonary endothelial permeability to proteins, because an elevation of pulmonary microvascular pressure (Pmv), induced by inflation of a left atrial balloon catheter, produced the same increases in Qlym and protein clearance as in normal sheep after comparable increases in Pmv. The increases in Qlym and protein clearance can be explained by an increase in pulmonary vascular surface area. ADP-induced PA decreased the arterial oxygen tension, which was sustained for the 3 h duration of the study; the arterial carbon dioxide tension did not change and the arterial pH decreased (P less than 0.05) after PA. Chronic depletion of platelets with antiplatelet serum prevented the increases in Qlym and protein clearance and the arterial hypoxemia, indicating that these changes were the direct result of PA. Thus ADP-induced PA in sheep increased pulmonary fluid filtration and protein clearance by an increase in the vascular surface area. Also PA produced a rapid and prolonged arterial hypoxemia, which may result from the release of vasoactive and bronchoactive factors causing a maldistribution of ventilation and perfusion.

Blood pressure lowering action of adenosine diphosphate and related compounds.

It was found upon intravenous injection of adenosine and its mono-, di-, and triphosphate in the rat that ADP produced the greatest fall in arterial blood pressure. At low dose levels ADP was about 147 times as potent as adenosine and about 45 times as potent as AMP or ATP on an equimolar basis. The rat is more sensitive to the blood pressure lowering action of the adenosine compounds than other species thus far tested.