Renal failure in 57 925 patients undergoing coronary procedures using iso-osmolar or low-osmolar contrast media

We compared the Swedish Coronary Angiography and Angioplasty Registry with the Swedish 'Hospital Discharge Register' to assess contrast media (CM)-induced renal failure. Hospitals used only one type CM. From 2000 to 2003, iodixanol (iso-osmolar) was used in 45 485 patients, ioxaglate (low osmolar) in 12 440 subjects. To include the earlier used CM iohexol (low osmolar), analysis extended back to 1990 (86 334 patients). Incidence of clinically significant renal failure was greatest for patients receiving the iso-osmolar CM iodixanol (1.7%). Ioxaglate-treated patients had a significantly lower renal failure incidence (0.8%, P<0.001). The odds ratio for iodixanol-treated patients was significantly higher than for ioxaglate (1 vs 0.48, P<0.001). In subsets of either diabetic patients or patients with previous renal failure, odds ratios for renal failure remained greater in the iodixanol groups (P<0.01). Hospitals switching CM to iodixanol experienced a doubling in clinically significant renal failure after cardiac procedures. Dialysis was required in 0.2% of patients receiving iodixanol, which was significantly higher (P<0.01) than for ioxaglate-treated patients (0.1%). Iohexol-treated patients had a similar low risk for developing clinically significant renal failure (0.9%) as ioxaglate. In conclusion, risk of developing renal failure and required dialysis after coronary procedures is higher when patients received iodixanol than ioxaglate or iohexol.     

低渗非离子造影剂对肾小管上皮细胞凋亡的作用及其机制

目的 探讨低渗非离子型造影剂碘必乐诱导体外培养的人肾小管上皮细胞（HK-2细胞）凋亡的作用及机制。 方法 体外培养的HK-2细胞,分为阴性对照组、不同剂量（1.16、4.63、18.5、74、296 gI/L）的碘必乐作用组（作用时间为6 h）。通过流式细胞仪、Hoechst 33258染色观察细胞凋亡的比例和形态学变化;Western印迹方法检测凋亡蛋白天冬氨酸半胱氨酸蛋白酶3（caspase-3）的表达水平,并选取作用最强的剂量（296 gI/L）刺激2、4、6、12 h,观察caspase-3表达变化。选取不同剂量碘必乐作用1 h,与阴性对照组比较,观察细胞外信号调节激酶（ERK）和p38丝裂原活化蛋白激酶（MAPK）信号通路磷酸化水平的变化,并观察不同剂量p38MAPK抑制剂SB203580对碘必乐诱导的caspase-3和Bcl-2表达的影响。 结果 流式细胞仪检测结果示74、296 gI/L碘必乐作用下细胞凋亡率较阴性对照显著升高（均P < 0.05）。Hoechst 33258染色结果示296 gI/L碘必乐可致明显的细胞凋亡形态学改变,凋亡细胞核呈致密浓染或核碎裂。Western印迹检测方法表明,碘必乐以剂量和时间依赖方式诱导细胞内caspase-3表达,以296 gI/L作用12 h表达最强;各剂量碘必乐作用下细胞内ERK1/2磷酸化水平与阴性对照组的差异均无统计学意义（均P > 0.05）,而一定剂量的碘必乐处理组细胞内p38MAPK磷酸化水平较阴性对照组显著升高（均P < 0.05）。应用p38MAPK特异性抑制剂（30 μmol/L）预处理2 h可以阻断细胞内p38MAPK信号通路的磷酸化,抑制碘必乐诱导的细胞内caspase-3表达并部分上调Bcl-2表达,与碘必乐阳性对照组的差异均有统计学意义（P < 0.05）。 结论 低渗非离子型造影剂碘必乐以剂量和时间依赖方式诱导体外培养的HK-2细胞凋亡,其机制可能与上调caspase-3和下调抗凋亡蛋白Bcl-2有关,而p38MAPK信号通路的激活可能参与了该过程的调控。     

Evaluation of left ventricular function and coronary sinus blood flow during exercise after aortocoronary bypass surgery. Influence of revascularization of the left anterior descending artery

Left ventricular function and coronary sinus blood flow at rest and during exercise were evaluated in 27 patients after aortocoronary bypass surgery and in 13 normal subjects (G-C). Twenty patients (G-1) had successfully revascularized left anterior descending artery (LAD). In 7 patients (G-2), the revascularization for LAD was not complete. There was no difference among 3 groups in stroke work index (SWI), left ventricular end-diastolic pressure (LVEDP) and coronary sinus blood flow (CSF) at rest. SWI during exercise in G-2 (44.7 +/- 14.7 g. M/beat/m2) was significantly lower than that in G-1 and G-C (67.9 +/- 15.0, 77.2 +/- 17.0 g.M/beat/m2) (p less than 0.02, p less than 0.002). LVEDP during exercise in G-2 (32 +/- 6 mmHg) was significantly higher than that in G-1, G-C (17 +/- 7, 13 +/- 3 mmHg) (p less than 0.001, p less than 0.001). CSF during exercise in G-2 (160 +/- 64 ml/min) was significantly lower than that in G-1, G-C (357 +/- 79, 290 +/- 113 ml/min) (p less than 0.001, p less than 0.002). These data indicated that left ventricular function during exercise and coronary sinus blood flow reserve for exercise in patient with completely revascularized LAD was significantly better than that in patients with incompletely revascularized LAD.     

Akinetic versus dyskinetic left ventricular aneurysms diagnosed by gated scintigraphy: difference in surgical outcome

Forty-one patients selected for left ventricular aneurysm resection and coronary artery bypass grafting were studied by gated radionuclide ventriculography, and right heart catheterization before and after operation to establish whether the presence of paradoxically systolic expansion, as defined by radionuclide ventriculography, influenced the surgical outcome. Patients with systolic paradoxically moving left ventricular aneurysms (n = 28) improved their functional classification (New York Heart Association) (p less than 0.01) and exercise tolerance (watt-minutes) (p less than 0.001) compared with preoperative values, in contrast to the patients with akinetic aneurysms (n = 13), whose status remained unchanged. Left ventricular ejection fraction at rest (p less than 0.001) and exercise (p less than 0.0001) improved along with a significant reduction in left ventricular end-diastolic (p less than 0.002) and end-systolic volume indices (p less than 0.001) among the patients with paradoxical left ventricular aneurysms versus no change in the akinetic group. In a multivariate analysis of different preoperative variables, the presence of dyskinesia was found to be the only independent predictor of a favorable surgical outcome (p less than 0.004). In conclusion, the presence of dyskinesia represents an important marker of the outcome after aneurysmectomy.     

Succinylcholine does not worsen bupivacaine-induced cardiotoxicity in pentobarbital-anaesthetized dogs

The intravascular injection of a large dose of bupivacaine induces electrophysiological cardiac impairment, mainly by slowing ventricular conduction velocity, and haemodynamic depression, by a decrease in myocardial contractility. When cardiotoxicity occurs, succinylcholine rapidly stops convulsions. However, the possible interactions between bupivacaine and succinylcholine on cardiac electrophysiology and haemodynamic status have never been investigated. Thus, we used an experimental electrophysiological model involving closed-chest dogs. Three groups (n = 6) of pentobarbital-anaesthetized dogs were given 0.2 mg.kg-1 atropine iv. Dogs in Group 1 were given saline. The others received 4 mg.kg-1 bupivacaine iv over ten seconds. Dogs in Group 2 were then given saline and those in Group 3 were then given 2 mg.kg-1 succinylcholine iv from one to two minutes after the administration of bupivacaine. The following electrophysiological variables were measured: heart rate represented by RR interval (RR), PR, atria-His (AH), and His-ventricle (HV) intervals, QRS duration, and QT interval corrected for heart rate (QTc). The following haemodynamic variables were measured: mean aortic pressure (MAoP), the peak of the first derivative of left ventricular pressure (LV dP/dt max), and LV end diastolic pressure (LVEDP). Comparison between Groups 1 and 2 showed that bupivacaine induced more than 100% HV interval lengthening and QRS widening (P less than 0.01), prolonged QTc interval by more than 25% (P less than 0.01), and decreased LV dP/dt max by more than 50% (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)     

Acute hemodynamic effects of pericardial closure in man

The acute hemodynamic effects of pericardial closure were studied in 30 patients with normal left ventricular function, who were undergoing coronary artery bypass surgery. Closure of the pericardium resulted in decreases in arterial blood pressure (P less than 0.01), cardiac index (P less than 0.001), mean right atrial (P less than 0.001), mean pulmonary artery (P less than 0.001) and pulmonary capillary wedge pressure (P less than 0.001). The observed hemodynamic changes are probably caused by a change in the ventricular pressure-volume relationships.     

Hemodynamic and cardiac electrophysiologic effects of lidocaine-bupivacaine mixture in anesthetized and ventilated piglets

BACKGROUND: The sensory blockade induced by a lidocaine-bupivacaine mixture combines the faster onset of lidocaine and the longer duration of bupivacaine. The current study compared the effects of large doses lidocaine (16 mg/kg), bupivacaine (4 mg/kg), and a mixture of 16 mg/kg lidocaine-4 mg/kg bupivacaine on hemodynamic and cardiac electrophysiologic parameters in anesthetized and ventilated piglets. METHODS: After carotid artery cannulation, a double micromanometer measured mean aortic pressure, left ventricular end diastolic pressure, and the first derivative of left ventricular pressure. Electrocardiogram recording and a bipolar electrode catheter measured RR, PQ, QRS, QT C, JT C, AH, and HV intervals. Lidocaine, bupivacaine, or the mixture was administered intravenously over 30 s, and studied parameters were measured throughout 30 min. RESULTS: Mean aortic pressure decreased in all groups ( P < 0.05). The first derivative of left ventricular pressure was decreased in all groups ( P < 0.001) but to a greater extent with the mixture compared with lidocaine ( P < 0.04). RR, QT C, and JT C intervals were similarly increased in all groups ( P < 0.05). In all groups, PQ, AH, HV, and QRS intervals were widened ( P < 0.001). The lengthening of PQ was greater with bupivacaine ( P < 0.02). The lengthening of AH was greater and delayed with bupivacaine compared with lidocaine ( P < 0.03). The lengthening of HV and the widening of QRS were greater and delayed with bupivacaine ( P < 0.01). The widening of QRS was greater with the mixture than with lidocaine ( P < 0.01). CONCLUSIONS: The alterations of ventricular conduction parameters are greater with 4 mg/kg bupivacaine than with a mixture of 16 mg/kg lidocaine-4 mg/kg bupivacaine, whereas the hemodynamic parameters are similarly altered.     

帕瑞昔布钠对急性心肌梗死大鼠心功能的影响

目的 评价帕瑞昔布钠对急性心肌梗死大鼠心功能的影响.方法 成年雄性SD大鼠24只,体重230～250 g,随机分为3组(n=8):假手术组(S组)、急性心肌梗死组(AMI组)和帕瑞昔布钠组(P组).AMI组和P组采用结扎左冠状动脉前降支的方法制备大鼠急性心肌梗死模型,S组冠状动脉穿线但不结扎;24 h后P组腹腔注射帕瑞昔布钠8 mg/kg,1次/d,连续3 d,AMI组用生理盐水替代.术后第4天测定并记录左心室收缩压(LVSP)、左心室舒张末期压(LVEDP)、左心室收缩压最大上升速率(+dp/dtmax)和左心室收缩压最大下降速率(-dp/dtmax);采集颈总动脉血样3 ml,采用放射免疫法测定血浆血栓素A2(TXA2)和前列腺素I2(PGI2)的浓度,并计算PGI2/TXA2;采血后取左心室心肌组织,测定梗死面积,计算心肌梗死体积.结果 与S组比较,AMI组和P组LVSP、±dp/dtmax、血浆PGI2浓度和PGI2/TXA2降低,LVEDP和血浆TXA2浓度升高(P＜0.05).与AMI组比较,P组LVSP、±dp/dtmax、血浆PGI2浓度和PGI2/TXA2升高,LVEDP和血浆TXA2浓度降低(P＜0.05).AMI组和P组心肌梗死体积比较差异无统计学意义(P＞0.05).结论 帕瑞昔布钠可改善急性心肌梗死大鼠左心室功能,其机制与调节PGI2/TXA2相对平衡有关.     

盐酸戊乙奎醚后处理对心肌缺血-再灌注大鼠心功能的影响

目的探讨盐酸戊乙奎醚后处理对心肌缺血-再灌注(IR)大鼠心功能的影响。方法选择SPF级健康雄性Wistar大鼠32只,8周龄,体重220~250 g。将大鼠随机分为四组:假手术组(S组)、假手术+盐酸戊乙奎醚组(SP组)、IR组和IR+盐酸戊乙奎醚后处理组(IP组),每组8只。S组冠状动脉左前降支仅穿线不结扎,30 min后经尾静脉注射生理盐水1 mg/kg。SP组冠状动脉左前降支仅穿线不结扎,30 min后经尾静脉注射盐酸戊乙奎醚1 mg/kg。IR组冠状动脉左前降支穿线结扎30 min后,松开结扎线,再灌注3 h。于再灌注(松开结扎线)前即刻经尾静脉注射生理盐水1 mg/kg。IP组于再灌注前即刻经尾静脉注射盐酸戊乙奎醚1 mg/kg。于开胸前5 min、再灌注后3、6 h,采用经胸超声心动图监测大鼠左心室舒张末压(LVEDP)、左心室收缩末压(LVESP)、左心室射血分数(LVEF)、左心室缩短分数(LVFS),采用智能血压计监测大鼠尾动脉MAP,采用ELISA法检测血清肌钙蛋白T(cTnT)浓度。结果与开胸前5 min比较,再灌注后3、6 h IR组和IP组LVEDP明显升高,LVESP、LVEF、LVFS、MAP明显降低(P<0.05);再灌注后3、6 h S组、IR组和IP组血清cTnT浓度明显升高(P<0.05)。与再灌注后3 h比较,再灌注后6 h IR组LVEDP、血清cTnT浓度明显升高,LVESP、LVEF、LVFS、MAP明显降低(P<0.05)。与S组比较,再灌注后3、6 h IR组和IP组LVEDP、血清cTnT浓度明显升高,LVESP、LVEF、LVFS、MAP明显降低(P<0.05)。与IR组比较,再灌注后3、6 h IP组LVEDP、血清cTnT浓度明显降低,LVESP、LVEF、LVFS、MAP明显升高(P<0.05)。S组和SP组上述指标差异均无统计学意义。结论盐酸戊乙奎醚后处理能够维持血流动力学稳定,降低cTnT浓度,改善心肌缺血-再灌注大鼠的心功能。     

Influence of desflurane on regional distribution of coronary blood flow in a chronically instrumented canine model of multivessel coronary artery obstruction

The influence of desflurane on myocardial perfusion measured by a microsphere technique during a total occlusion of the left anterior descending coronary artery and concomitant moderate or severe stenosis of the left circumflex coronary artery was evaluated in chronically instrumented dogs. Hemodynamics, regional contractile function, and myocardial blood flow were measured during the conscious state and after anesthesia with desflurane (8.2%-9.2% and 12.5%-12.7%) with and without control of arterial pressure. Total left anterior descending occlusion produced in combination with a left circumflex coronary artery stenosis significantly (P less than 0.05) increased heart rate and left ventricular end diastolic pressure in the absence of desflurane anesthesia. Desflurane, administered only in the presence of left anterior descending occlusion and left circumflex stenosis, significantly (P less than 0.05) decreased mean arterial pressure, left ventricular systolic pressure, and left ventricular positive dP/dt50 without change in heart rate. Blood flow to the subendocardium of normal myocardium was reduced during the high concentration of desflurane (P less than 0.05), but perfusion of the subepicardium and midmyocardium was maintained at conscious levels. When the left circumflex stenosis was of moderate severity, only blood flow to the subendocardium distal to the stenosis was reduced by desflurane (P less than 0.05). In the presence of a severe stenosis, perfusion was decreased in the subepicardium, midmyocardium, and subendocardium of the stenotic zone (P less than 0.05). During the reduction in arterial pressure produced by desflurane, collateral blood flow in the left anterior descending region was reduced in dogs with either a moderate or severe left circumflex stenosis (P less than 0.05). When arterial pressure and heart rate conditions observed in the postocclusion conscious state were restored during the high concentration of desflurane, myocardial blood flow in all regions returned to those levels present in the conscious state (P less than 0.05). Ratios of flow between occluded and normal zones were decreased when hypotension produced by desflurane was uncontrolled, but when arterial pressure and heart rate were adjusted to conscious postocclusion levels using partial thoracic aorta occlusion and atrial pacing, the ratio remained at conscious control levels regardless of the degree of left circumflex stenosis severity (P less than 0.05). Results of this investigation indicate that desflurane does not redistribute blood flow away from collateral-dependent myocardium to other regions via a "coronary steal" mechanism in a chronically instrumented canine model of multivessel coronary artery disease.     

Experimental model of left ventricular failure

A model of chronic cardiac failure has undergone extensive hemodynamic investigation. Under anesthesia the homonymous and second diagonal coronary arteries of sheep have been ligated. The resulting myocardial infarction caused significant acute hemodynamic impairment (paired two-tailed t tests), mean pulmonary artery pressure increasing from 7.31 +/- 0.94 to 13.80 +/- 1.19 mm Hg (p less than 0.001), pulmonary artery diastolic pressure increasing from 4.94 +/- 1.03 to 11.13 +/- 1.27 mm Hg (p less than 0.001), and directly measured left ventricular end-diastolic pressure increasing from 9.31 +/- 1.52 to 17.42 +/- 1.82 mm Hg (p less than 0.001) after infarction documented with invasive monitoring. There was a hemodynamically significant left ventricular aneurysm (paired two-tailed t tests) in animals studied 3 months later, with increased mean pulmonary artery pressure from 7.20 +/- 1.15 to 13.80 +/- 2.00 mm Hg (p = 0.009), an increase in pulmonary artery diastolic pressure from 4.60 +/- 1.30 to 12.10 +/- 2.06 mm Hg (p = 0.006), and an increase in left ventricular end-diastolic pressure from 11.00 +/- 1.94 mm Hg before infarction to 17.00 +/- 2.69 mm Hg (p = 0.038). We conclude that this is a useful model of chronic left ventricular failure that is reproducible and applicable to investigations of therapeutic options in chronic heart failure.     

Influence of incremental preoperative risk factors on the perioperative outcome of patients undergoing emergency versus urgent coronary artery bypass grafting

A retrospective analysis of 127 patients with impending myocardial infarction undergoing coronary artery bypass grafting was performed to evaluate incremental risk factors associated with perioperative mortality and morbidity. Fifty-four patients (group 1) were operated upon as emergencies within 24 h and 73 patients underwent urgent coronary revascularization within a mean of 3.4 days (group II) after admission. The incidence of non-transmural myocardial infarctions (NTMI), haemodynamic parameters, the number of diseased vessels and the incidence of a preceding percutaneous coronary dilatation (PTCA) were not statistically different between the groups. The overall perioperative mortality was 8.7% (16.7% group I, 2.7% group II). Major non-fatal complications were frequent in the surviving collective including low cardiac output in 14 patients (12.1%) and transmural or subendocardial perioperative infarction in 12 patients (10.3%). Perioperative mortality was associated with reduced left ventricular myocardial function (P less than 0.001), operation within 24 hr after onset of anginal symptoms (P less than 0.001) or subendocardial infarction (P less than 0.025) in the 4 weeks before operation. Perioperative mortality was independent of the degree of coronary stenosis, number of distal anastomoses or performance of a coronary endarterectomy. Of the patients, 90.5% (87.5% of group I and 92.3% of group II) included in a mean follow-up of 16.8 months (range 5-27 months) were graded into Canadian Heart Functional Class I. Successful coronary surgery for acute myocardial ischaemia results in excellent late functional recovery. The major risk factors for fatal perioperative outcome are reduced left ventricular function and the necessity of every early surgical intervention.     

Experimental study on coronary bypass grafts--functional and pathologic comparison of late changes in various coronary grafts]

The internal thoracic artery (ITA) has excellent long-term patency when used as a conduit for coronary artery bypass (CAB), but there are still some problems, such as flow capacity and limited graft length of the ITA. This study was performed to evaluate the functional and pathologic late changes in left ITA grafts (LITAG), vein grafts (VG), ITA-vein (ITA-VG) and ITA-ITA composite grafts (ITA-ITAG) in a canine model of coronary artery bypass. Twenty-nine adult mongrel dogs underwent bypass of the left circumflex coronary artery (CX) with one of the above grafts. More than five months postoperatively (mean follow up period 245 +/- 78 days), changes in graft flow (CX flow in control group), mean aortic pressure (AoP), left ventricular end diastolic pressure (LVEDP), diastolic pressure time index/tension time index (DPTI/TTI), left atrial pressure (LAP) and right atrial pressure (RAP) with atrial pacing were compared with control group, and postmortem specimens were examined microscopically. With atrial pacing, AoP and RAP did not change in any group. Increases in graft flow, LVEDP and LAP with decrease in DPTI/TTI were observed in ITAG and ITA-ITAG groups, but these changes were similar to control group. On the other hand, increases in LVEDP and LAP with decreases in graft flow and DPTI/TTI were observed in VG and ITA-VG groups, and these changes were different from control group. No atherosclerotic change without anastomotic site was observed in any ITA which was used in ITAG, ITA-ITAG and ITA-VG groups, while intimal thickening and irregular dilatation were observed in al veins which were used in VG and ITA-VG groups. In conclusion, this study shows that ITA is a excellent conduit for CAB because of sufficient flow capacity and no atherosclerosis without anastomotic site in a long-term period. And to elongate ITA as a CAB graft, ITA-ITAG could be more appropriate than ITA-VG.     

T grafts with the right internal thoracic artery to left internal thoracic artery versus the left internal thoracic artery and radial artery: flow dynamics in the internal thoracic artery main stem.

OBJECTIVE: Complete arterial coronary artery bypass grafting with 2 grafts can be achieved even in triple vessel disease by use of a T configuration. There is still uncertainty whether the coronary flow reserve in the main stem of the left internal thoracic artery is sufficient to supply more than 1 anastomosed coronary vessel. METHODS: Between March 1996 and February 1999, 251 patients with multivessel coronary artery disease underwent complete arterial revascularization with T grafts, using either the left internal thoracic artery with the free right internal thoracic artery graft (n = 73, group I) or the left internal thoracic artery and radial artery (n = 178, group II). A mean of 4.0 (group I) versus 4.3 (group II) coronary vessels were anastomosed per patient. One week (n = 92) and 6 months (n = 28) after the operation, flow was measured in the proximal left internal thoracic artery with a Doppler guide wire. Maximum flow was determined after injection of adenosine (30 microg). RESULTS: The in-hospital mortality was 2.7% (group I) versus 2.3% (group II). At angiography (n = 142, 56.6%) the patency rate was 96.3% (group I) versus 98.2% (group II). There was no significant difference between baseline flow, maximum flow, and coronary flow reserve between the 2 groups. Coronary flow reserve increased in both groups within the first 6 postoperative months (group I, 1.85 +/- 0.31 vs 2.77 +/- 0.77, P =.0002; group II, 1.82 +/- 0.4 vs 2.53 +/- 0.73, P =.009). CONCLUSION: Both variants of T grafts allow for complete arterial revascularization with good perioperative results. The flow reserve of the proximal internal thoracic artery is adequate for multiple coronary anastomoses irrespective of the choice of the second arterial graft.     

Hemodynamic changes during off-pump coronary artery bypass anastomosis in patients with coexisting mitral regurgitation: improvement with milrinone

We hypothesized that mitral regurgitation (MR) would be exacerbated, cardiac index (CI) decreased, and mean pulmonary artery pressure (MPAP) increased in patients with coexisting MR during off-pump coronary artery bypass (OPCAB) anastomosis, and that milrinone could ameliorate increases in MR that occur during OPCAB anastomosis. Subjects comprised 140 patients scheduled for elective OPCAB divided into three groups: patients without MR (MR(-) group; n = 57), patients with MR (MR(+) group; n = 41), and patients with MR who received milrinone (M+MR(+) group; n = 42). Patients with grade 1+ or 2+ MR were included, whereas those with grade 3+ or 4+ MR were excluded. Hemodynamic variables were measured after the induction of anesthesia and during anastomosis. IV infusion of milrinone (0.5 microg . kg(-1) . min(-1)) started immediately after the induction of anesthesia in the M+MR(+) group. CI was significantly decreased (P < 0.0001), and MPAP and MR were significantly increased (P < 0.001) during left coronary anastomosis in the MR(+) group compared with the MR(-) group. CI was significantly higher (P < 0.001), and neither MPAP nor MR were increased (P < 0.05) during left coronary artery anastomosis in the M+MR(+) group compared to the MR(+) group. In patients with MR, anastomosis of the left coronary artery branches was associated with decreased CI and increased regurgitation and MPAP. In such patients, treatment with milrinone helps to stabilize hemodynamics during anastomosis.     

Increased plasma apolipoprotein(a) levels in IDDM patients with microalbuminuria

Patients with insulin-dependent diabetes mellitus (IDDM) have a significantly increased risk of macrovascular disease, particularly if they have persistent proteinuria. To determine whether altered levels of apolipoprotein(a) [apo(a)], the plasminogenlike glycoprotein of the potentially atherogenic lipoprotein(a); contribute to the increased risk of atherosclerosis, apo(a) levels were measured in 107 patients with IDDM and compared with nondiabetic control subjects and male elective coronary artery graft patients. Apo(a) levels were increased in diabetic patients with microalbuminuria (geometric mean 245 U/L, 95% confidence interval [CI] 142-427, n = 30) and albuminuria (mean 196 U/L, 95% CI 97-397, n = 18) with levels comparable to patients with coronary artery disease (mean 193 U/L, 95% CI 126-298, n = 40), which were higher than in the control group (mean 107 U/L, 95% CI 85-134, n = 140; P = 0.016). Apo(a) levels in diabetic patients without microalbuminuria (mean 86 U/L, 95% CI 63-116, n = 59) were comparable with the control population and less than in those with microalbuminuria (P less than 0.001) and albuminuria (P = 0.014). The elevated apo(a) levels found in patients with IDDM and increased urinary albumin loss may contribute to their heightened risk of macrovascular disease.     

High-dose hydromorphone (Dilaudid) for coronary artery bypass surgery

The hemodynamic effects of high-dose hydromorphone hydrochloride (H), 1.25 mg/kg, were investigated in 10 patients with normal ventricular function undergoing coronary artery bypass graft (CABG) surgery. One patient with unstable angina was excluded from the study because of hypotension and facial flushing after a 6-mg test dose of H. Nine patients showed no significant change in heart rate (HR), mean arterial pressure (MAP), cardiac index (CI), left ventricular stroke work index (LVSWI), systemic vascular resistance (SVR), pulmonary capillary wedge pressure (PCWP), or coronary perfusion pressure (CPP) after H; central venous pressure (CVP) increased significantly (P less than 0.05). Loss of consciousness did not occur reliably after H. The addition of 50% N2O to H produced significant decreases in CI and LVSWI (P less than 0.05). Hemodynamic responses to tracheal intubation, skin incision, and sternotomy included depression of CI, elevation of SVR, and increased MAP (P less than 0.05). Vasodilators were required in eight patients before aortic cannulation and after extracorporeal circulation. Mean time to awakening was 7.6 hr after the full dose of H, and extubation was performed the morning after surgery (21 hr after H) according to our usual practice. We conclude that very large doses of H (equivalent in analgesic terms to 10 mg/kg of morphine sulfate) are well tolerated by most patients undergoing CABG surgery, but unconsciousness and complete suppression of sympathetic responses require supplementation of H with additional anesthetic agents or vasodilators.     

Thoracic epidural anaesthesia decreases the incidence of ventricular arrhythmias during acute myocardial ischaemia in the anaesthetized rat

The aim of the present investigation was to study the effect of high thoracic epidural anaesthesia (TEA) on the incidence of ventricular arrhythmias after ligation of the left coronary artery in chloralose-anaesthetized rats. Forty animals were randomly assigned to receive either 40-50 microliter of bupivacaine (5 mg/ml) or saline in implanted thoracic epidural catheters. TEA decreased mean arterial pressure (MAP) from 118 +/- 5 mmHg to 72 +/- 4 mmHg and heart rate (HR) from 450 +/- 9 to 387 +/- 8 beats/min, while epidural saline did not affect MAP and HR. In both groups coronary artery ligation induced a transient decrease in MAP within the first 5-10 min after ligation. In the control group HR increased, during the 30-min post-ligation period, from 453 +/- 9 to 474 +/- 10 beats/min (P less than 0.05) while no significant change was seen in the TEA group. In both groups the mortality rate was 10%. In the TEA group 30% and in the control group 0% had normal sinus rhythm during the recording period (P less than 0.001). The incidence of ventricular fibrillation and/or tachycardia was significantly lower (P less than 0.05) in the TEA group (20%) compared to the control group (53%). The incidence of ventricular extrasystoles did not differ between the two groups. We conclude that TEA-induced blockade of sympathetic afferents and efferents may offer protection against malignant ventricular arrhythmias in the early phase of acute myocardial infarction.     

Acadesine (AICA-riboside) improves postischemic cardiac recovery.

To test if acadesine (5-aminoimidazole-4-carboxamide riboside), a purine precursor, has cardioprotective effects, 16 dogs were placed on total cardiopulmonary bypass and subjected to global myocardial ischemia. Hemodynamic recovery was compared between a control (n = 8) group receiving standard cardioplegia and an acadesine (n = 8) group pretreated with intravenous acadesine (2.5 mg.kg-1.min-1 for 5 minutes, then 0.5 mg.kg-1.min-1) before ischemia, during ischemia, and until 10 minutes after removal of the aortic cross-clamp. Additionally, in the acadesine group the cardioplegia also contained 20 mumol/L acadesine. While the dogs were on cardiopulmonary bypass, global warm myocardial ischemia was induced by aortic cross-clamping for 5 minutes under normothermic conditions to simulate an angioplasty accident. Five minutes after aortic cross-clamping, hypothermic cardioplegia (30 mL/kg) was administered. The left anterior descending coronary artery was occluded before the first infusion of cardioplegia to simulate poor cardioplegia delivery that can occur during an emergency coronary artery bypass procedure after an angioplasty accident. The left anterior descending artery occlusion was released, and additional cardioplegia (15 mL/kg) infusions were made every 30 minutes thereafter during 120 minutes of cardioplegic ischemia. Thirty minutes after reperfusion, all animals in both groups were weaned from bypass and recovery data were obtained to compare with baseline preischemic values. There were no significant differences in heart rate, left atrial pressure, or systemic vascular resistance between groups after weaning from bypass. Peak developed pressure recovered to 79% +/- 19% (mean +/- standard deviation) of baseline in the acadesine group compared with 56% +/- 22% in the control group (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Influence of obesity on the early and long term results of surgery for coronary artery disease

In order to determine the effect of obesity on the results of coronary artery bypass graft (CABG) surgery, we compared 250 obese patients undergoing CABG procedures between 1984 and 1987 with 250 age- and sex-matched controls of normal body mass index (BMI) undergoing CABG in the same period. The obese group had a greater incidence of diabetes mellitus (p less than 0.02), hypertension (p less than 0.05), hyperlipidaemia (p less than 0.05), and left main stem coronary artery disease (p less than 0.001). No differences were identified in the surgery performed, but obesity was associated with prolonged total bypass time (p less than 0.05). Operative mortality was 0.8% in both groups. Multivariate analysis demonstrated obesity to be an independent risk factor for perioperative morbidity (p less than 0.05). Univariate: respiratory (p less than 0.01); leg wound (p less than 0.001); myocardial infarction (p less than 0.02); arrhythmias (p less than 0.02); sternal dehiscence (p less than 0.02). At a mean follow-up time of 36.9 months obese patients exhibited a greater incidence of significant recurrent angina (p less than 0.01), which was associated with further weight gain (mean 12.2 kg; linear correlation: p less than 0.001, r = 0.891). Although in CABG surgery operative mortality is not increased in obese patients, aggressive pre- and postoperative weight control is indicated to reduce both perioperative morbidity and the incidence of recurrent angina.