Cardiac resynchronization improves coronary blood flow

Asynchronous ventricular activation, induced by left bundle branch block, is known to have deleterious effects on the systolic and diastolic functions of the left ventricle (LV). Cardiac resynchronization therapy (CRT) has been proposed as a complementary method to improve the LV systolic performance by restoring the synchronized contraction patterns in patients with advanced heart failure and left bundle branch block. However, the effect of CRT on myocardial blood flow is not well established. In the present study, we therefore examined the coronary blood flow in 20 patients with idiopathic dilated cardiomyopathy, implanted with a biventricular pacemaker according to the established CRT criteria. Color Doppler settings were adjusted for the optimal coronary flow imaging, and coronary flow velocities were obtained in all patients. Typical diastolic predominant phasic Doppler spectrum of the distal left anterior descending coronary artery (LAD) was recorded. Conventional echocardiographic variables, peak values of the diastolic and systolic LAD velocities, and the velocity time integrals were measured for three or five consecutive beats during CRT with pacemaker on and off. Successful CRT with biventricular pacing increased coronary blood flow velocities of the distal LAD in addition to its well-known benefits on the systolic and diastolic LV performance in patients with significant dyssynchrony. CRT decreased duration of mitral regurgitation and increased diastolic filling time. Peak diastolic velocities and velocity time integral of the distal LAD were increased significantly. In conclusion, successful CRT with biventricular pacing improves coronary blood flow velocities of the distal LAD.     

Total and effective coronary blood flow in coronary and noncoronary heart disease

There are no data available concerning total coronary blood flow to the whole heart (CBF) in man. "Effective" or "nutrient" coronary blood flow to the whole heart (MBF), supposedly a measure of flow through exchanging channels of the coronary circulation, has been measured but its validity has not been established. Accordingly, CBF and MBF were measured in 9 normal subjects, 26 patients with coronary heart disease (CHD), and 19 with noncoronary, mostly valvular heart disease (NCHD), by coincidence counting 84Rb technique. Two methods were used: single bolus (24 cases) and continuous infusion (30 cases). Various other parameters including myocardial oxygen utilization (MVO2) and lactate extraction ratio were determined. In the normal subjects CBF (386 +/- 77 ml/min) was significantly higher (P < 0.05) than in CHD (288 +/- 124 ml/min) and NCHD (292 +/- 111 ml/min). Likewise the normal MBF (380 +/- 81 ml/min) was significantly higher (P < 0.01) than in CHD (251 +/- 105 ml/min) as well as NCHD (258 +/- 104 ml/min). The myocardial Rb extraction ratio epsilon Rb) was significantly lower in normal subjects (39 +/- 9%) than in CHD (50 +/- 7%) and NCHD (52 +/- 11%) and this supports the view that epsilon Rb is flow-dependent. In both CHD and NCHD there was significant diminution of MVO2 as well as CBF. In CHD this was accompanied by a significant anaerobic trend but in NCHD it was not. It might therefore appear that in CHD, MVO2 is determined by perfusion whereas in NCHD, perfusion is determined by MVO2. In comparing CBF with MBF by paired observation testing, there was no significant difference in the normals (P > 0.3), whereas the differences were significant in CHD (P < 0.01) and NCHD (P < 0.02). This was merely a reflection of a reduced ratio of myocardial to total body epsilon Rb in CHD and NCHD, and available evidence indicates that this may be an expression of depressed transport of Rb+ rather than true shunting.     

Percutaneous assessment of coronary blood flow and cardiac biomarkers

The aim of this study was to compare blood flow determined by coloured microspheres vs. Doppler intravascular ultrasound (US) combined with angiography. A second endpoint was to assess cardiac troponin I (cTnI) as a marker of myocardial injury. Doppler and microspheres were compared in 11 closed chest pigs. Blood flow was measured by catheter-based percutaneous technique in the left circumflex artery (LCx) and compared with coloured microspheres injected in the left ventricle. cTnI was measured in all pigs (73). The mean blood flow (mL/min-1) was 23.3 +/- 8.7 vs. 21.9 +/- 12.1 by Doppler vs. microspheres (p = 0.156), correlation coefficient r = 0.90, p = 0.006. The mean coronary flow with Doppler technique and microspheres in the middle LCx was 22.9 +/- 7.6 vs. 21.2 +/- 6.2 (p = 0.077), and distal 23.9 +/- 10.9 vs. 23.1 +/- 12.1 (p = 0.698). Coronary blood flow measured by Doppler and angiography was comparable to myocardial blood flow measured by coloured microspheres injected in the left atrium or the left ventricle. cTnI was more sensitive to ischaemia than CK-MB mass.     

Improvement of coronary morphology and blood flow after stenting

Intravascular ultrasound (IVUS) and intracoronary Doppler (ICD) were performed in eight patients (54.3±6.5 years, 6 male) immediately after PTCA and after stenting. ICD was also performed before PTCA. After PTCA, IVUS has demonstrated intimal rupture in all patients. After stenting, IVUS revealed wall wrapping of the intimal flap with a free lumen in all patients. The lumen diameter was 2.42±0.55 mm after PTCA and was 2.74±0.49 mm after stenting (p<0.001). The cross-sectional area increased from 4.70±1.99 mm² post-PTCA to 6.40±2.15 mm² post-stent (p<0.005). Coronary flow velocity reserve, calculated by the ratio of mean flow velocity at rest and after intracoronary papaverine administration, increased from 2.05±1.01 to 2.99±1.14 after PTCA (p = 0.015); and increased to 4.51±1.33 after stenting (p<0.001). The morphological data derived from IVUS correlated with the functional information obtained with ICD. In addition to its established role in bail out situations, stent implantation may be considered when a suboptimal morphological and functional result has been demonstrated.     

冠状动脉慢血流的诊断与治疗进展

冠状动脉慢血流（coronary slow flow,CSF）现象是指排除冠状动脉痉挛、冠状动脉扩张、冠状动脉成型术后、冠状动脉造影术中冠状动脉内气体栓塞、心脏瓣膜病、结缔组织病等因素外,在冠状动脉造影中没有发现冠状动脉存在明显病变,而远端血流灌注延迟的现象。Tamble等于1972年首先报道了部分有胸痛症状的病例,经冠状动脉造影显示没有病变但血流速度明显减慢。此后随着冠状动脉造影的普及,这种现象逐渐为人们所重视。     

Prostacyclin and regional coronary blood flow in experimental myocardial infarction

Infusion of prostacyclin (PGI₂) has been reported to affect infarct size and myocardial blood flow favourably in various animal models of myocardial ischaemia. Recent data suggest that a similar effect of PGI₂ may occur also in humans with acute myocardial infarction. We addressed the hypothesis that PGI₂ redistributes myocardial blood flow following coronary ligation, and that this effect favours perfusion of myocardium at risk and thereby limits infarct size. Following ligation of a distal branch of the left coronary artery in anaesthetized dogs, PGI₂ (2–4 ng/kg/min) was infused for 72 h. Regional myocardial blood flow was assessed immediately after the coronary ligation and at the end of the drug infusion, by injection of ⁵⁷Co- and ¹¹³Sn-labelled microspheres, respectively. Coronary ligation reduced regional coronary blood flow by 40–70%. During the subsequent 72 h the blood flow increased, being at the end of the period 50–70% of the flow in the non-ischaemic myocardium. PGI₂ did not affect the spontaneous improvement of regional myocardial blood flow, as assessed at the end of the infusion. PGI₂ also failed to affect infarct size, either when expressed in relation to total left ventricular mass, or in relation to area at risk. We conclude that PGI₂, when infused immediately after coronary ligation in dogs in a clinically relevant dose, neither affects regional myocardial blood flow in the ischaemic regions, nor the size of the myocardial infarction.     

Role of K+ ATP channels and adenosine in the regulation of coronary blood flow during exercise with normal and restricted coronary blood flow.

Regulation of coronary vasomotor tone during exercise is incompletely understood. We investigated the contributions of K+ ATP channels and adenosine to the coronary vasodilation that occurs during exercise in the normal heart and in the presence of a coronary artery stenosis. Dogs that were chronically instrumented with a Doppler flow probe, hydraulic occluder, and indwelling catheter on the left anterior descending coronary artery were exercised on a treadmill to produce heart rates of approximately 200 beats/min. By graded inflation of the occluder to produce a wide range of coronary stenosis severities, we determined the coronary pressure-flow relation. K+ atp channel blockade with intracoronary glibenclamide (10-50 microgram/kg per min) decreased coronary blood flow during exercise at coronary pressures within and below the autoregulatory range, indicating that coronary K+ ATP channel activation is critical for producing coronary vasodilation with either normal arterial inflow or when flow is restricted by a coronary artery stenosis. Adenosine receptor blockade with intravenous 8-phenyltheophylline (5 mg/kg) had no effect on coronary flow at pressures within the autoregulatory range but decreased flow at pressures < 55 mmHg. In contrast, in the presence of K+ ATP channel blockade, the addition of adenosine receptor blockade further decreased coronary flow even at coronary pressures in the autoregulatory range, indicating increased importance of the vasodilator influence of endogenous adenosine during exercise when K+ atp channels are blocked. Intracoronary adenosine (50 microgram/kg per min) increased coronary flow at perfusion pressures both within and below the autoregulatory range. In contrast, selective K+ ATP channel activation with intracoronary pinacidil (0.2-5.0 microgram/kg per min) increased flow at normal but not at lower coronary pressures (< 55 mmHg). This finding demonstrates that not all K+ ATP channels are activated during exercise at pressures in the autoregulatory range, but that most K+ ATP channels are recruited as pressures approach the lower end of the autoregulatory plateau. Thus, K+ ATP channels and endogenous adenosine play a synergistic role in maintaining vasodilation during exercise in normal hearts and distal to a coronary artery stenosis that results in myocardial hypoperfusion during exercise.     

Enalaprilat,losartan and LU 135252 in coronary blood flow regulation

BACKGROUND: High plasma levels of angiotensin II are found in several pathologies such as hypertension, heart failure and myocardial infarction. The effect of high concentrations of angiotensin II on coronary circulation is not well defined. The aim of the present study was to assess coronary blood flow regulation during tachycardia in the presence of elevated coronary plasma levels of angiotensin II, and the changes induced by ACE inhibition and blockade of angiotensin II and endothelin-A receptors. DESIGN: Left anterior coronary artery was catheterized in 38 pigs to infuse the study drugs. Saline was infused for 15 min. Then, the first atrial pacing was performed. The pigs were distributed to: Group 1 (n = 7) angiotensin II; Group 2 (n = 7) enalaprilat + angiotensin II; Group 3 (n = 9) the bradykinin B2 antagonist HOE 140 + enalaprilat + angiotensin II; Group 4 (n = 7) losartan + angiotensin II; and Group 5 (n = 8) endothelin-A receptor antagonist LU 135252 + angiotensin II. After giving these infusions, a second pacing was repeated. RESULTS: The increase in coronary blood flow induced by pacing with angiotensin II was reduced from 181 +/- 21% to 116 +/- 37% (P = 0.006 vs. saline). Enalaprilat, losartan and LU 135252 restored the capacity of coronary blood flow to increase during pacing (151 +/- 39%, 162 +/- 35% and 161 +/- 16%, respectively; P = NS, vs. saline), while HOE 140 abolished the effect of enalaprilat. CONCLUSIONS: Moderately elevated coronary concentrations of angiotensin II reduced coronary blood flow during pacing. Enalaprilat, losartan and LU 135252 restored the hyperaemic coronary flow to similar values observed with saline. The beneficial effect of ACE inhibition is mediated through an increase in bradykinin.     

Alpha adrenoceptor regulation of coronary artery blood flow in normal and stenotic canine coronary arteries

The response of systemic blood pressure, heart rate, lead II ECG and left circumflex (LCX) coronary artery blood flow to left cardiac sympathetic nerve stimulation was measured in pentobarbital-anesthetized, open chest, spinal transected and vagotomized dogs. After beta adrenoceptor blockade, left cardiac sympathetic nerve stimulation produced frequency dependent decreases in LCX blood flow. Selective alpha-2 adrenoceptor blockade with idazoxan produced a greater inhibition of this decrease in LCX blood flow than did selective alpha-1 adrenoceptor blockade with prazosin. In an additional population of dogs which were similarly prepared but were not spinally transectioned or pretreated with a beta adrenoceptor antagonist, left cardiac sympathetic nerve stimulation produced an increase in LCX blood flow in all animals which reached a maximum within 40 sec, and then began to decline slowly. However, after beta adrenoceptor blockade, identical stimulation parameters produced only a decline in LCX blood flow which returned to the level of control resting blood flow by the end of the stimulation period. Both selective alpha-2 adrenoceptor blockade with idazoxan and selective alpha-1 adrenoceptor blockade with prazosin produced an inhibition of the LCX blood flow decrease provoked by left cardiac sympathetic nerve stimulation in dogs pretreated with beta adrenoceptor antagonists. Idazoxan produced a slightly greater inhibition of the LCX blood flow decrease than did prazosin, suggesting a greater role for postjunctional vascular alpha-2 adrenoceptors in LCX blood flow regulation during cardiac sympathetic nerve stimulation. The presence of a severe coronary artery stenosis reduced, but did not inhibit, the increase in LCX blood flow in response to cardiac sympathetic nerve stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)     

Hypoxemia after coronary bypass surgery modeled by resistance to oxygen diffusion

OBJECTIVE: To evaluate a model describing postoperative hypoxemia after cardiac surgery by using two variables, i.e., shunt and resistance to oxygen diffusion (Rdff). DESIGN: Estimation of these two variables in normal subjects and postoperative cardiac patients. SETTING: The pulmonary function laboratory for the normal subjects and the intensive care unit for the cardiac patients. PATIENTS/SUBJECTS: Nine postoperative cardiac patients and six healthy subjects. INTERVENTIONS: Inspired oxygen fraction was varied in normal subjects and in cardiac patients 3-6 hrs after surgery. This variation occurred in four to seven steps to achieve arterial oxygen saturations in the range 0.90-1.00. MEASUREMENTS AND MAIN RESULTS: Measurements were taken of arterial oxygen saturation, cardiac output, ventilation, and end-tidal gases at each inspired oxygen fraction. These measurements gave the following estimates for the normal subjects: shunt = 3.9+/-5.4% (mean +/- SD) and Rdiff = -5+/-16 torr/(L/min) [-0.7+/-2.2 kPa/(L/min)]; for the cardiac patients: shunt = 7.7+/-1.8% and Rdiff = 212+/-230 torr/(L/min) [28.2+/-30.6 kPa/(L/min)]. The increase in Rdiff (P = .01) was sufficient to explain the observed hypoxemia in these patients. The value for shunt was not significantly increased in the patients (p = .09). The two-variable model (shunt and Rdff) gave a better prediction of arterial oxygen saturation than a model with shunt as the only variable (p = .02). CONCLUSIONS: In cardiac patients requiring supplementary oxygen, the respiratory abnormality could, in our model, be best described by an increased Rdiff, not by an increased shunt value.     

冠脉介入对冠心病患者血流及炎症因子的影响

目的观察和分析经皮冠状动脉介入(PCI)干预后冠状动脉血流及基质金属蛋白酶-9(MMP-9)、白细胞介素-6(IL-6)等炎症因子水平的变化。方法选取46例择期行PCI术的急性冠脉综合征(ACS)患者作为PCI组,选取22例行常规冠状动脉造影检查的患者作为CA组,对两组患者术前、术后外周血标本中以及PCI患者术中病变局部血标本中的MMP-9、IL-6水平和术后冠状动脉的校正的TIMI计帧数(c TFC)进行检测和比较。结果 PCI组患者使用造影剂量和术后c TFC均显著高于CA组(P0.05);PCI组患者术后外周血标本IL-6水平较术前显著升高(P0.05)且显著高于CA组(P0.05),PCI组患者术中病变局部血标本IL-6水平显著高于术前或术后的外周血标本(P0.05);PCI组患者的术中病变局部血标本的IL-6水平(r=0.589)、术中局部血标本与术前外周血标本MMP-9水平的差值(r=0.372)和术中局部血标本与术前外周血标本IL-6水平的差值(r=0.628)与患者的c TFC呈正相关(P0.05)。结论 PCI术可显著改善ACS患者的冠脉血流,局部PCI操作、血流再灌注等因素可引起病变局部血清炎症因子水平的上升,其变化幅度较外周血更加显著。     

Absolute volumetric coronary blood flow measurement with digital subtraction angiography

The problems associated with visual interpretation of coronary arteriograms have been well-documented. There is a need for more physiologic means of assessing coronary artery stenosis during routine coronary arteriography. Volumetric coronary blood flow assessed as a function of time can be a valuable aid in the analysis of functional significance of arterial obstruction. A volumetric coronary blood flow measurement technique was investigated in a swine animal model using phase matched temporal subtraction images. The left anterior descending (LAD) coronary artery of swine animal models were instrumented with an ultrasound flow probe (US) and a vascular occluder producing stenosis. Contrast material injections (2–4 ml/sec for 3 sec) were made into the left coronary ostium during image acquisition. Phase-matched temporal subtraction (DSA) images were used to measure volumetric coronary blood flow in the LAD. In addition, a technique for automatic estimation of iodine calibration slope was also investigated. In 49 independent comparisons, the mean coronary blood flow (FPA) correlated extremely well with the mean US flow (FPA = 0.92US + 1.42 ml/min, r = 0.99, standard error of estimate (SEE) = 4.32 ml/min). Further more, the automatic iodine calibration technique was shown to be very accurate. In conclusion, accurate volumetric coronary blood flow measurements can be made before the onset of significant changes in coronary blood flow due to contrast injection.     

冠状动脉慢血流现象与血液生化指标的相关性分析

目的:探讨冠状动脉慢血流现象(coronary slow flow phenomenon,CSFP)与血尿酸(UA)、同型半胱氨酸(Hcy)、红细胞压积(Hct)及红细胞分布宽度(RDW)的相关性。方法:对因胸闷、胸痛症状行冠状动脉造影术(coronary angiography,CAG)住院患者的病例资料进行回顾性分析,选择其中CAG显示心外膜冠状动脉无明显狭窄但存在CSFP的121例患者作为CSFP组(SCF组),另将CAG证实心外膜冠状动脉完全正常且血流正常的606例患者设为正常血流组(NCF组)。比较两组患者UA、Hcy、Hct及RDW的差异,并分析CSFP与上述指标、UA与其他生化指标间的相关性。结果:SCF组UA、Hcy、Hct水平均较NCF组升高(P0.001);两组RDW水平差异无统计学意义。条件Logistic回归分析发现,UA、Hcy、Hct均为CSFP的危险因素;Spearman相关及偏相关性分析示UA与Hcy正相关(P0.001)。结论:UA、Hcy、Hct是CSFP发生的危险因素,UA与Hcy可能协同促进CSFP的发生发展。     

血液细胞成分与女性冠状动脉慢血流的关系

目的 探讨血液细胞成分与女性冠状动脉慢血流(slow coronary flow,SCF)的关系.方法 经冠状动脉造影证实冠状动脉狭窄＜40％的女性患者169例,根据校正的TIMI血流计帧法分为SCF组95例,对照组74例,比较2组临床血液细胞成分变化.结果 2组年龄、高血压病、2型糖尿病及吸烟史比例比较差异无统计学意义(P＞0.05);SCF组前降支动脉、回旋支动脉和右冠状动脉校正的TIMI血流帧数(28.2(23.5,32.9)、34.0(26.0,42.0)、28.0(22.0,34.0))高于对照组(17.6(13.2,20.0)、20.0(16.0,24.0)、18.0(16.0,22.0)帧)(P＜0.01),而白细胞计数((5.95(5.21,7.01))×109/L)、中性粒细胞与淋巴细胞比值(1.70(1.35,2.28))、红细胞分布宽度(42.2(40.4,43.8)fL)、血小板平均体积(10.5(9.9,11.1)fL)与对照组((6.09(5.54,7.03))×109/L、2.06(1.45,2.59)、41.6(40.0,43.6)fL、10.5(10.0,11.0)fL)比较差异无统计学意义(P＞0.05);SCF组红细胞压积(38.90％(36.70％,41.70％))高于对照组(38.00％(35.60％,40.00％))(P＜0.05).结论 红细胞压积是女性冠状动脉SCF的影响因素,高水平红细胞压积可能参与了SCF的病理生理过程.     

Systolic and diastolic changes in human coronary blood flow during Valsalva manoeuvre

Valsalva manoeuvre is reported to be sometimes successful for the relief of angina pectoris. The present study investigated how haemodynamic changes produced by Valsalva manoeuvre can interact to improve the relationship between cardiac work and coronary blood flow. Ten male subjects aged 53 ± 12 years (SD) were considered. Blood velocity in the internal mammary artery, previously anastomosed to the left descending coronary artery, was studied with Doppler technique. The subjects performed Valsalva manoeuvres by expiring into a tube connected to a mercury manometer, to develop a pressure of 40 mmHg. The arterial blood pressure curve was continuously monitored with a Finapres device from a finger of the left hand. During expiratory effort, an increase in heart rate and a decrease in arterial pulse pressure were followed by a more delayed and progressive increase in mean and diastolic pressures. Systolic blood velocity markedly decreased along with the reduction in pulse pressure and increase in heart rate. By contrast, diastolic and mean coronary blood velocities did not show any significant change. Since it is known that the Valsalva manoeuvre strongly reduces stroke volume and cardiac output, it is likely that a reduction in cardiac work also takes place. Since in diastole, i.e. when the myocardial wall is better perfused, coronary blood velocity did not show any significant reduction, it is likely that unchanged perfusion in the presence of reduced cardiac work is responsible for the relief from angina sometimes observed during Valsalva manoeuvre. It is also likely that the increase in heart rate prevents the diastolic and mean blood coronary velocity from decreasing during the expiratory strain, when an increased sympathetic discharge could cause vasoconstriction through the stimulation of the coronary α‐receptors.     

Tachycardia and coronary blood flow: non-invasive estimation during Valsalva manoeuvre and exercise

Summary. Simultaneous changes in cycle length and coronary blood flow were studied during Valsalva manoeuvre and supine cycloergometer exercise test in 10 male patients (mean age 4812 years) who had successfully undergone myocardial revascularization by surgical anastomosis of the left internal mammary artery on the left anterior descending coronary artery. Blood velocity curves in the left internal mammary artery were obtained by a non-invasive continuous-wave Doppler probe at rest, in the last phase of the expiratory effort of the Valsalva manoeuvre and at the maximum load attained during the exercise test. Mean arterial pressure by sphygmomanometer, and cardiac cycle length on the basis of Doppler recording were measured. Mean blood velocity, the length of the blood column entering the coronary bed at each cycle (cardiac cycle times mean velocity), an index of blood cell acceleration (the ratio of mean velocity to cardiac cycle), and an index of coronary resistance (the ratio of mean pressure to mean velocity), were calculated. For approximately the same change in cycle length, coronary resistance decreased in exercise, with an increased mean velocity, but increased in Valsalva, with no changes in mean velocity. The length of the blood column entering the coronary bed at each cycle was unchanged in exercise, with a marked increase in the acceleration index, while it decreased in Valsalva. Therefore, we hypothesize that tachycardia has a limiting effect on sympathetic coronary constriction in Valsalva when cardiac external work is decreased, and an additional vasodilatory effect on coronary bed in exercise when external work is increased.,     

Cardiac output,coronary blood flow,and blood gases during open-chest standard and compression-active-decompression cardiopulmonary resuscitation

OBJECTIVE: To determine whether open-chest compression-active-decompression (CAD) could improve cardiac output, coronary blood flow, blood gases, and resuscitation compared to open-chest manual compression in a porcine model of cardiac arrest. DESIGN: Prospective, randomized laboratory investigation for measurement of cardiac output, coronary blood flow, arterial and mixed venous blood gases and potassium levels, and return of spontaneous circulation. SUBJECTS: Ten pigs each weighing approximately 36.4 kg. INTERVENTIONS: Following preparation of the model and opening of the chest, ultrasonic flow probes were placed on the ascending aorta and left anterior descending artery. Cardiac arrest was induced by epicardial pacing. Subjects received either open-chest CAD or open-chest manual compression. After 10 min of arrest, defibrillation was attempted. MEASUREMENTS AND MAIN RESULTS: Cardiac output fell to 46+/-53% (95% CI: -20 to 112) and 41+/-14% (95% CI: 23-59) (P>0.05) of baseline with CAD and manual methods at 5 min after arrest, respectively. Similarly, coronary blood flow fell to 33+/-14% (95% CI: 16-50) and 42+/-16% (95% CI: 22-62) (P>0.05) of baseline at 5 min. Both groups developed similar levels of metabolic acidosis, mixed venous hypoxemia, and hyperkalemia, with potassium levels: 6.5+/-4.0 meq/l (95% CI: 1.6-11.4) at 5 min and 7.5+/-4.6 meq/l (95% CI: 1.8-13.2) at 10 min in the CAD group and 5.8+/-2.0 meq/l (95% CI: 3.4-8.3) at 5 min and 6.1+/-1.4 meq/l (95% CI: 4.4-7.9) at 10 min in the manual group. Levels of hyperkalemia were inversely proportional to the square of PvO(2). One pig in each group was resuscitated after defibrillation. CONCLUSION: We found no benefit using CAD. Both low coronary blood flow and hyperkalemia may have limited resuscitation.