Monitoring anticoagulation during percutaneous coronary interventions

Summary Monitoring of the activated clotting time in the interventional catheterization suite is essential to minimize the risk of acute thrombotic occlusion, as well as to minimize the risk of bleeding-related complications postprocedure. Based on the technique used, a Hemochron ACT of >400 seconds or a HemoTec ACT of >300 seconds is associated with a low risk of acute thrombotic occlusion. Avoiding an ACT of >500 seconds should minimize the risk of procedure-related bleeding complications.     

择期经皮冠状动脉腔内成形术对左室功能的影响

目的:选择行择期PTCA的38例首次急性心肌梗死患者,测定其术前、后的左心功能,旨在探讨择期PTCA对左室功能的影响。方法:所有患者均于PTCA术前1～2天及术后1周、3个月进行心脏彩超检查。超声检查左室功能指标包括:容量指标:EDV、ESV;收缩功能指标:EF、△T％;舒张功能指标:E/A、ACT_E。结果:PTCA术后1周与术前相比:EDV、ESV和ACT_E有所减少,EF、△T％有所增高,但均未达统计学意义。PTCA术后3个月与术前相比:EDV、ESV有明显降低(P<0.05),EF、△T％有明显增高(P<0.05),E/A、ACT_E有继续改善趋势,但未达统计学意义。结论:AMI接受择期PTCA有益于患者左室功能的恢复,术后1周改善不显著,至术后3个月除左室舒张功能外均有显著改善。     

Heparin dosing for percutaneous coronary angioplasty: Use of body surface area to improve initial activated clotting time values

Background: Activated clotting time (ACT) values during percutaneous transluminal coronary angioplasty (PTCA) after the initial 10,000 U heparin bolus are often below target values of 350 or 400 s (Hemochron) and have to be supplemented with additional heparin. This study evaluated the initial 10 min post-heparin bolus clotting time value using a body surface area (BSA)-adjusted heparin bolus versus the traditional 10,000 U heparin bolus. Hypothesis: Body surface area adjustment of initial heparin dosing prior to PTCA will be more effective in reaching target ACT values compared with the 10,000 U heparin bolus method. Methods: Twenty-seven patients receiving the BSA-adjusted heparin bolus were compared with 27 age- and gender-matched controls who had received the traditional heparin bolus. The adjusted heparin bolus formula used was [BSA(m²)/1.3m²] X 10,000 U of heparin. Results: The success rate at reaching the target value of 400 s was 13 of 27 (48.1%) and 2 of 27 (7.4%) for the BSA-guided and 10,000 U heparin-guided groups, respectively (p < 0.01). The success rate at reaching the 350 s target value was 25 of 27 (92.6%) and 6 of 27 (22.2%) for the BSA-guided and 10,000 U heparin-guided groups, respectively (p < 0.01). The 95% confidence intervals for the difference in success between the BSA-guided and 10,000 U heparin-guided groups were 0.19–0.62 and 0.52–0.89 for the 400 s and 350 s ACT targets, respectively. Conclusion: Body surface area adjustment of initial heparin dosing is a more effective method of reaching the initial ACT target values of 350 and 400 s compared with the traditional method prior to PTCA. This conclusion applies to the Hemochron ACT device and arterial samples, and adjustments may need to be made for other devices and/or venous samples.     

Minor myocardial injury after elective uncomplicated successful PTCA with or without stenting: detection by cardiac troponins.

Cardiac troponins are sensitive and specific markers for the detection of minor myocardial injury. However, they have been rarely used to monitor myocardial injury after coronary stenting. The purpose of the study was to measure cardiac troponin I (cTnI) and cardiac troponin T (cTnT) levels after elective uncomplicated successful percutaneous transluminal coronary angioplasty (PTCA) with or without coronary stenting and to compare their results with serum creatinine kinase MB isoenzyme (CKMB). CTnI and cTnT levels were compared with those of CK or CKMB in 98 consecutive patients with stable angina undergoing elective uncomplicated successful PTCA with stenting (n = 71) or without stenting (n = 27). Markers were measured before and 6, 12, 24, and 48 hr after the procedure. Peak postprocedural levels for each marker were compared and related to angiographic and procedural characteristics as well as to the occurrence of side-branch occlusion. None of the patients had abnormal markers before the procedure. Abnormal postprocedural values of one or more markers were observed in 28 patients (29%), 23 after stenting and 5 after PTCA alone. The frequencies of abnormal cTnI and cTnT levels were significantly higher than that of CKMB after coronary intervention (26% and 18% vs. 7%; P = 0.00016 and 0.015, respectively), with cTnI being the most significant. When compared with troponin-negative patients, abnormal cardiac troponin values were significantly related to total time of inflation (223 +/- 128 vs. 170 +/- 105 sec; P = 0.008) and inflation maximal pressure (12.9 +/- 2.3 vs. 12.0 +/- 2.7 atm; P = 0.04). Small side-branch occlusion was noticed in 36% of the troponin-positive patients and in 6% of the troponin-negative group (P = 0.00047). In conclusion, minor myocardial injury is not uncommon after elective uncomplicated successful PTCA with or without stenting. Cardiac troponins, especially cTnI, are more sensitive than CKMB for the detection of this minor myocardial injury. Total time of inflation and inflation maximal pressure are predictors of postprocedural elevation of cardiac troponins. Side-branch occlusion may account for some, but not all, periprocedural minor myocardial injury.     

Influence of temperature and time before centrifugation of specimens for routine coagulation testing

The accurate standardization of the preanalytical phase is of pivotal importance for achieving reliable results of coagulation tests. Because information on the suitable storage conditions for coagulation testing is controversial, we aimed at investigating the sample stability with regard to the temperature and time before centrifugation. The activated partial thromboplastin time (aPTT), prothrombin time (PT), fibrinogen and D-dimer were assayed in specimens collected from 26 consecutive patients on antivitamin K therapy on the ACL TOP analyzer. Three primary 3.6-ml siliconized evacuated tubes containing 0.109 mol/l buffered trisodium citrate were sequentially collected from each patient. These three tubes were mixed, pooled and divided into seven identical aliquots. The first aliquot was immediately centrifuged according to the standard protocol [1500 g for 15 min at room temperature (RT)] and analyzed. The other aliquots were left for 3, 6 and 24 h, respectively, at RT or 4 degrees C, and then centrifuged and analyzed. Test results were compared with those obtained on the reference specimen. Statistically significant prolongations were observed for aPTT in all the samples. Such differences exceeded the analytical quality specifications for desirable bias in the samples stored for 24 h. A significant reduction, yet comprised within the desirable bias, was observed for PT and fibrinogen in uncentrifuged specimens stored at RT for 3 and 6 h. No significant biases could be recorded in D-dimer. In conclusion, a 6-h storage of uncentrifuged specimens at either RT or 4 degrees C may still be suitable to achieve results of routine coagulation testing comprised within the analytical quality specifications for desirable bias.     

Reproducibility and variability of activated clotting time measurements in the cardiac catheterization laboratory.

The objective of this study was to characterize the reproducibility and variability in the measurement to the activated clotting time (ACT) when performed on two different types of instruments, the HemoTec ACT (Medtronic) and the Hemochron 801 (International Technidyne). The ACT has evolved into the most common point-of-care test used in the cardiac catheterization lab to manage patient heparinization. Since the test has not been standardized, different systems frequently produce different results under the same clinical conditions. Duplicate paired ACT tests (n = 885) from 359 patients were performed on both instruments. Prothrombin times (PT) and activated partial thromboplastin times (aPTT) were also determined on subsets of these same samples (PT = 533; aPTT = 487). The performance and relationships between the two tests were determined using a variety of statistical analytical techniques. The average difference between the ACT devices was only 8 sec, yet more than 60% of the measurements varied by more than 10%. Over one-fourth of measurements varied by more than 20%. The reproducibility to the HemoTec instrument was superior to the Hemochron instrument across the entire range of ACTs measured (mean coefficient of variation 2.4% +/- 3.1% vs. 7.2% +/- 6.1% for HemoTec and Hemochron, respectively; P < 0.00001; range = 65-555 sec). The relationship between the two ACTs was nonlinear. In therapeutic ranges used for interventional procedures (200-350 sec), HemoTec and Hemochron ACTs are not comparable to one another. Statistical comparative analysis indicated that the HemoTec ACT has better overall performance.     

Activated clotting time differential is a superior method of monitoring anticoagulation following coronary angioplasty

The standard high-range activated clotting time (sHR ACT) is used to monitor anticoagulation postangioplasty (PTCA), but may be unreliable. We assessed the accuracy of a new method we termed the ACT differential (ACT Diff), obtained by measuring the difference between an sHR ACT and a heparinase ACT from the same sample. Heparinase removes heparin from its sample and provides a current heparin-free baseline. For phase 1 of the study, the sHR ACT, ACT Diff, and laboratory APTT were measured in 250 samples from 75 PTCA patients. In 125 samples with an APTT prolonged but within measurement range, linear regression against the APTT was performed. The correlation coefficient was 0.74 for the ACT Diff and 0.24 for the sHR ACT. An ACT Diff of 15–25 sec was found to equal an APTT of 2.5–3.5 × control. In 50 samples with a normal activated partial thromboplastin time (APT), there was good differentiation by the ACT Diff of results from those adequately heparinized, with a value of 0.9 ± 4.4 sec. The sHR ACT was 114 ± 15.5 sec, and could not reliably distinguish between anticoagulated and nonanticoagulated samples. In 75 samples obtained with a high APTT (above measurement range), the ACT Diff was >30 sec in 95% of samples, and again this allowed differentiation from therapeutic samples. The equivalent sHR ACT was 148 sec, and could not reliably distinguish between anticoagulated and overanticoagulated samples as the ACT Diff could. In phase 2, to examine the clinical usefulness of the ACT Diff, 286 patients were managed post-PTCA by starting heparin when ACT Diff fell to <50 sec, maintaining ACT Diff at 15–25 sec during heparin infusions, and following cessation of heparin, by removing sheaths when the ACT Diff was <7 sec. These patients were compared to a control group of 250 patients. Major bleeding (5% vs. 0.5%, P < 0.005) and minor bleeding (30% vs. 13%, P < 0.001) were significantly reduced in the group managed using the ACT Diff. The reduction in bleeding was thought to be due to the rapid availability of reliable results. Abrupt closure was low in both groups (0% with ACT Diff vs. 0.8%). No other thrombotic events occurred. Following phases 1 and 2, the ACT Diff replaced the APTT in all PTCA patients at this institution. In the 18 mo from July 1993, 1,104 patients were managed this way. Incidence of major bleeding (0.2%), transfusion requirement (0.1%), false anneurysm (0.6%), and abrupt closure during heparin infusion (0.1%) remained low. In conclusion, the ACT Diff is more accurate than an sHR ACT, and its clinical use in PTCA patients is associated with a very low incidence of complications from anticoagulation. Its routine use should be considered by units unable to obtain rapid APTT results. © 1996 Wiley-Liss, Inc.     

Activated clotting times and activated partial thromboplastin times in patients undergoing coronary angioplasty who receive bolus doses of heparin

The accurate assessment of coagulation status is an important part of interventional procedures performed in the cardiac catheterization laboratory. While the traditional clinical means of assessing heparin anticoagulation has been with the activated partial thromboplastin time (APTT), the activated coagulation time (ACT) has come into widespread use in the catheterization laboratory as an assay of whole blood clotting time which can be performed rapidly at the bedside. The purpose of the present study was to (1) assess the anticoagulant effect of a 10,000 U bolus of heparin in PTCA patients and (2) document the relationship between ACTs and APTTs in a subset of these patients. Baseline and postheparin ACTs were measured using a HemoTec coagulation timer in 545 unselected PTCA patients. The average baseline ACT was 120 ± 22 sec. After a 10,000 U bolus of heparin the average ACT was 249 ± 44 sec; 58% of patients had an ACT < 250 sec, 17% had an ACT between 250 and 275 sec, 12% had an ACT between 275 and 300 sec, and 13% had an ACT >300 sec. A total of 175 paired ACT and APTT measurements were obtained in a random subset of these patients at baseline, after heparinization, and at 4–6 hr intervals after the procedure. The APTT was limited by absolute upper and lower limits of 150 and 22 sec; there were no such limits on the ACT. When limiting values were excluded, there was a strong overall correlation between ACT and APTT measurements (r = 0.92, p 0.001). We conclude that the activated coagulation time provides an accurate and reliable assessment of anticoagulation status. This test appears to be ideally suited for patients undergoing interventional procedures. There are, however, substantial differences in the automated systems currently in clinical use. The percent of patients achieving a target ACT of greater than 300 sec, as measured by a HemoTec system, after a 10,000 U bolus of heparin is low. These results are not extrapolatable to other ACT measurement techniques. © 1992 Wiley-Liss, Inc.     

Equipment-dependent mechanical distortion of a tortuous right coronary artery during PTCA

Guidewires can distort a tortuous vessel, creating the illusion of an intraluminal defect that does not exist. This case report demonstrates the changing severity of defects in the same vessel seen with two different types of guidewires varying in stiffness. © 1996 Wiley-Liss, Inc.     

冠状动脉造影后即刻支架术与择期支架术的临床研究

目的比较冠状动脉造影后即刻支架术与择期支架术的成功率和并发症发生率，从而探讨即刻支架术的临床应用价值。方法对2005年1—12月在我科行冠状动脉造影后即刻支架术（即刻组，n=115例）和择期支架术（择期组，n=172例）患者的资料进行分析。结果A型和B型病变的成功率和并发症率两组间差异无统计学意义（P〉0．05），而C型病变的成功率即刻组低于择期组（P〈0．01），而并发症率高于择期组（P=0．05）。结论A型和B型病变冠状动脉造影后即刻支架术是临床可行的，而C型病变不宜冠状动脉造影后即刻支架术。因此，冠状动脉造影后即刻支架术有一定的临床应用价值。     

Enhancement of platelet inhibition of ticlopidine plus aspirin vs aspirin alone given prior to elective PTCA

Background In many patients today, elective percutaneous transluminalcoronary angioplasty is followed by implantation of coronarystents to achieve optimal results. The current medical strategyto prevent early reocclusion is the inhibition of platelet aggregationby administration of ticlopidine, in addition to aspirin, immediatelyafter the procedure. In order to inhibit platelet aggregationas early as possible, many centres begin to treat patients withadditional ticlopidine the day before elective coronary intervention.The aim of this study was to determine the effect of this strategyon platelet aggregation before angioplasty. Method Fifty-two consecutive patients admitted to hospital forelective balloon angioplasty were prospectively randomized toreceive either standard oral aspirin 100mg per day or standardtherapy plus 250mg ticlopidine at the time of admission andthe morning before angioplasty. Adenosine diphosphate-, collagen-and epinephrine-induced platelet aggregation was measured immediatelybefore the procedure by an investigator who was blinded concerningthe arm of therapy. Results The two groups of patients were comparable in termsof age, sex, body mass index, anginal state, time interval betweenapplication of study drug and coronary intervention. Patientson aspirin and ticlopidine had a mean maximal platelet aggregationof 36±12% with adenosine diphosphate as agonist. Forthe control group, 54±12% was measured (P<0·001).Myocardial infarction or emergency coronary bypass graftingdid not occur in either group. Local haemorrhagic complicationsat the arterial access site occurred in five (aspirin) and six(aspirin and ticlopidine) patients (P=ns) none of them requiringblood transfusion. Conclusion The additional application of ticlopidine to chronicaspirin therapy the day before elective coronary balloon angioplastyleads to a significantly higher inhibition of platelet aggregationat the time of the intervention. It seems to be safe comparedto the standard procedure.     

Novel perfusion sleeve for use during balloon angioplasty: Initial clinical experience

The perfusion sleeve (PS) is an “over-the-balloon” catheter designed to add perfusion capability to standard PTCA catheters. To evaluate the clinical effectiveness of this device, eight patients underwent standard PTCA with the PS retracted in the guide (Inflation 1-Control) and after deployment of the PS (Inflation 3-Control). Between standard inflations the PS was advanced and aligned with the already positioned PTCA balloon which was inflated for up to 15 minutes (Inflation 2-Perfusion). TIMI III flow was present in 5/7 and TIMI II flow in 2/7 patients during Inflation 2-Perfusion. Absolute ST segment shift (mm) on the ECG was significantly less at 3 minutes and prior to balloon deflation with the PS in place (1.0 ± 1.4 and 1.1 ± 1.1 mm) compared to Inflation 1-Control and Inflation 3-Control (2.6 ± 1.3 and 2.3 ± 0.3 mm) respectively (P ≤ 0.05). Use of the PS in conjunction with standard PTCA is feasible, provides perfusion during prolonged balloon inflations and reduces the magnitude of ischemia. Cathet. Cardiovasc. Diagn. 44:358–362, 1998. © 1998 Wiley-Liss, Inc.     

Successful treatment of severe intra-abdominal bleeding associated with disseminated intravascular coagulation using recombinant activated factor VII

Recombinant activated factor VII (rFVIIa) is indicated mainly for the treatment of patients with haemophilia and inhibitors. However, little information is available on the use of rFVIIa in the treatment of the severe bleeding associated with disseminated intravascular coagulation (DIC). We report a pregnant woman with DIC, who developed severe intra-abdominal bleeding after caesarean section. Despite treatment with fresh-frozen plasma, fibrinogen, platelet transfusions and surgery, the abdominal bleeding persisted and intravenous treatment with rFVIIa was initiated. The response to treatment was rapid, with control of the bleeding and resolution of the coagulopathy. No side-effects related to rFVIIa were noted. This case suggests a potential role for rFVIIa in the treatment of severe and refractory bleeding associated with DIC.     

老年急性心肌梗死患者急诊经皮冠状动脉腔内成形术疗效和安全性的临床观察

目的　评价老年急性心肌梗死患者急诊冠状动脉介入治疗的疗效和安全性。方法　对 135例急性心肌梗死患者行急诊冠状动脉介入治疗术 ,根据年龄分为≥ 70岁组 (43例 )和 <70岁组 (92例 )。比较两组手术成功率及住院随访结果。结果　≥ 70岁组与 <70岁组比较 ,手术成功率 (97.6 %vs 97.9%)和因介入需要急诊冠状动脉旁路移植术率 (2 .3%vs1%)差异无显著性意义 ;≥ 70岁组精神症状显著高于 <70岁组 (11.6 %vs2 .1%)。结论　老年急性心肌梗死患者急诊经皮冠状动脉腔内成形术是安全有效的。     

冠状动脉狭窄程度和部位对经皮腔内冠状动脉成形术时发生室性异位搏动的影响

目的 :探讨冠状动脉 (冠脉 )狭窄程度和部位与急性冠脉完全堵塞时产生室性心律失常的关系。方法 :对 10 0例冠脉狭窄 (5 0 %～ 95 % )患者行经皮腔内冠状动脉成形术 (PTCA)球囊充盈 ,球囊充盈前、充盈时及充盈后同步记录 12导联心电图。结果 :球囊阻塞冠脉时室性心律失常的发生率为 12 %。发生室性心律失常的患者冠脉狭窄程度轻 [(70± 13) % :(85± 14) % ,P <0 .0 1],无侧支循环 ,易出现 ST段变化 (P <0 .0 5 ) ,扩张左前降支比扩张左回旋支和右冠脉更易发生室性心律失常 (P <0 .0 5 )。结论 :轻度冠脉狭窄和左前降支狭窄行 PTCA时似易发生室性异位搏动。     

Assessment of coronary artery stenosis during PTCA by measurement of the trans-stenotic pressure gradient: Comparison with quantitative coronary angiography

A fibreoptic pressure sensor mounted on an 0 018 inch guidewire(Pressure Guide®, RadiMedical Systems, Uppsala, Sweden)was used to measure the trans-stenotic pressure gradient in20 patients admitted for percutaneous transluminal coronaryangioplasty (PTCA) of a single, discrete stenosis. Pressuremeasurements were made both at rest and during maximal vasodilatationinduced by intracoronary injection of papaverine. From the ratioof distal coronary pressure divided by the proximal pressure,the relative coronary flow reserve was calculated. The aim ofthe study was to compare the different pressure-derived parametersby correlating them to stenosis geometry estimated by quantitativecoronary angiography. There was a moderate correlation betweenbaseline pressure gradient and percent area stenosi r= 0.64,P<0.001 and minimal cross-sectional area; r= 0.45, P<0005.A higher correlation was found between hyperaemic pressure gradientand area stenosis (r= 080, P<0001) and minimal cross-sectionalareas, respectively (r= 0.55, P<0 005). The best correlationwas found between relative coronary flow reserve and area stenosis(r= 0.86, P<0.001) and minimal cross-sectional area (r= 0.70,P<0001). In conclusion, pressure measurement using a pressure guidewireis useful as a complement to angiography in evaluation of coronarystenoses during PTCA. Pressures should be measured during maximalvasodilatation. Relative coronary flow reserve calculated fromthe pressure measurements provides additional information aboutthe fraction of normal maximal flow possible in the presenceof a stenosis.     

急性心肌梗死直接PTCA后早期ST段改变及其临床意义

目的探讨急性心肌梗死（AM I）行直接经皮冠状动脉腔内成形术（PTCA）+支架术后心电图早期ST段回落幅度与左心室结构、功能的关系。方法首次患AM I并接受直接PTCA的患者32例。比较PTCA术前和术后1 hST段抬高的高度,按ST段下移>50%及ST段下移<50%,分别分为A组（21例）和B组（11例）。所有患者于术后4周进行临床评估和二维彩色多普勒超声心动图检查。结果随访期间两组患者均未发生死亡,A组心功能ⅢⅣ级2例,B组心功能ⅢⅣ级5例（P<0.05）。4周后A组左心室射血分数（LVEF）、收缩末容积指数（LVESVI）、舒张末容积指数（LVEDVI）和全心室壁运动指数（GWMSI）均显著优于B组（P<0.05）;梗死区室壁运动指数（RWMSI）在两组间无显著性差异。结论成功的直接PTCA后ST段的早期回落是反映心肌组织再灌注的简便可靠的指标,ST段回落>50%者的心脏功能、室壁运动及左心室重构情况明显优于ST段回落<50%者。