Efficacy of Pulsatile Flow Perfusion in Adult Cardiac Surgery: Hemodynamic Energy and Vascular Reactivity

Background: The role of pulsatile (PP) versus non-pulsatile (NP) flow during a cardiopulmonary bypass (CPB) is still debated. This study’s aim was to analyze hemodynamic effects, endothelial reactivity and erythrocytes response during a CPB with PP or NP. Methods: Fifty-two patients undergoing an aortic valve replacement were prospectively randomized for surgery with either PP or NP flow. Pulsatility was evaluated in terms of energy equivalent pressure (EEP) and surplus hemodynamic energy (SHE). Systemic (SVRi) and pulmonary (PVRi) vascular resistances, endothelial markers levels and erythrocyte nitric-oxide synthase (eNOS) activity were collected at different perioperative time-points. Results: In the PP group, the resultant EEP was 7.3% higher than the mean arterial pressure (MAP), which corresponded to 5150 ± 2291 ergs/cm3 of SHE. In the NP group, the EEP and MAP were equal; no SHE was produced. The PP group showed lower SVRi during clamp-time (p = 0.06) and lower PVRi after protamine administration and during first postoperative hours (p = 0.02). Lower SVRi required a higher dosage of norepinephrine in the PP group (p = 0.02). Erythrocyte eNOS activity results were higher in the PP patients (p = 0.04). Renal function was better preserved in the PP group (p = 0.001), whereas other perioperative variables were comparable between the groups. Conclusions: A PP flow during a CPB results in significantly lower SVRi, PVRi and increased eNOS production. The clinical impact of increased perioperative vasopressor requirements in the PP group deserves further evaluation.

Clinical monitoring of activated clotting time during cardiothoracic surgery: comparing the Hemochron® Response and Hemochron® Signature Elite

Introduction: The Activated Clotting Time (ACT) is commonly used to manage anticoagulation during cardiac surgery. The aim of this study was to compare the older manually operated Hemochron® Response and the automated Hemochron® Signature Elite. Methods: In this observational study the clinically relevant differences of both devices were investigated simultaneously, using duplicate measurements, in 29 patients who underwent a Coronary Artery Bypass Grafting (CABG) or Aortic Valve Replacement (AVR) in order to determine reliability, bias, and to detect which method has the lowest variation. Blood samples were obtained from the arterial line prior to surgery, after administration of 300 IU/kg heparin, 5 minutes after initiation of cardiopulmonary bypass and successively every 30 minutes, and after protamine administration. Results: A total of 202 measurements were performed. Of these 10 measurements were out of range in the Response and 9 in the Elite. About 27 single unstable magnet errors were seen in the Response versus no measurement errors in the Elite. No statistically significant differences between the Response (p = 0.22, Wilcoxon rank) and Elite (p = 0.064) duplicates were observed. The Response values were consistently higher during heparinization than the Elite measurements (p = 0.002, repeated measurements) with an average positive bias of around 56 seconds during heparinization (Bland-Altman). Overall, the coefficient of variation (CoV) increased during heparinization. Conclusion: The Elite was more reliable, but the variation was higher for the Elite than the Response. The observed positive bias in the Response compared to the Elite could affect heparin administration during surgery making the two systems not interchangeable.

Transit time flow measurement of coronary bypass grafts before and after protamine administration

Background Intraoperative graft assessment with tools like Transit Time Flow Measurement (TTFM) is imperative for quality control in coronary surgery. We investigated the variation of TTFM parameters before and after protamine administration to identify new benchmark parameters for graft quality assessment. Methods The database of the REQUEST (“REgistry for QUality AssESsmenT with Ultrasound Imaging and TTFM in Cardiac Bypass Surgery”) study was retrospectively reviewed. A per graft analysis was performed. Only single grafts (i.e., no sequential nor composite grafts) where both pre- and post-protamine TTFM values were recorded with an acoustical coupling index > 30% were included. Grafts with incomplete data and mixed grafts (arterio-venous) were excluded. A second analysis was performed including single grafts only in the same MAP range pre- and post- protamine administration. Results After adjusting for MAP, we found a small increase in MGF (29 mL/min to 30 mL/min, p = 0.009) and decrease in PI (2.3 to 2.2, p < 0.001) were observed after the administration of protamine. These changes were especially notable for venous conduits and for CABG procedures performed on-pump. Conclusion The small changes in TTFM parameters observed before and after protamine administration seem to be clinically irrelevant, despite being statistically significant in aggregate. Our data do not support a need to perform TTFM measurements both before and after protamine administration. A single TTFM measurement taken either before or after protamine may suffice to achieve reliable data on each graft’s performance. Depending on the specific clinical situation and intraoperative changes, more measurements may be informative. Trial registration Clinical Trials Number: NCT02385344, registered February 17th, 2015.

Optimal protamine dosing after cardiopulmonary bypass: The PRODOSE adaptive randomised controlled trial

Background The dose of protamine required following cardiopulmonary bypass (CPB) is often determined by the dose of heparin required pre-CPB, expressed as a fixed ratio. Dosing based on mathematical models of heparin clearance is postulated to improve protamine dosing precision and coagulation. We hypothesised that protamine dosing based on a 2-compartment model would improve thromboelastography (TEG) parameters and reduce the dose of protamine administered, relative to a fixed ratio. Methods and findings We undertook a 2-stage, adaptive randomised controlled trial, allocating 228 participants to receive protamine dosed according to a mathematical model of heparin clearance or a fixed ratio of 1 mg of protamine for every 100 IU of heparin required to establish anticoagulation pre-CPB. A planned, blinded interim analysis was undertaken after the recruitment of 50% of the study cohort. Following this, the randomisation ratio was adapted from 1:1 to 1:1.33 to increase recruitment to the superior arm while maintaining study power. At the conclusion of trial recruitment, we had randomised 121 patients to the intervention arm and 107 patients to the control arm. The primary endpoint was kaolin TEG r-time measured 3 minutes after protamine administration at the end of CPB. Secondary endpoints included ratio of kaolin TEG r-time pre-CPB to the same metric following protamine administration, requirement for allogeneic red cell transfusion, intercostal catheter drainage at 4 hours postoperatively, and the requirement for reoperation due to bleeding. The trial was listed on a clinical trial registry (ClinicalTrials.gov Identifier: NCT03532594). Participants were recruited between April 2018 and August 2019. Those in the intervention/model group had a shorter mean kaolin r-time (6.58 [SD 2.50] vs. 8.08 [SD 3.98] minutes; p = 0.0016) post-CPB. The post-protamine thromboelastogram of the model group was closer to pre-CPB parameters (median pre-CPB to post-protamine kaolin r-time ratio 0.96 [IQR 0.78–1.14] vs. 0.75 [IQR 0.57–0.99]; p < 0.001). We found no evidence of a difference in median mediastinal/pleural drainage at 4 hours postoperatively (140 [IQR 75–245] vs. 135 [IQR 94–222] mL; p = 0.85) or requirement (as a binary outcome) for packed red blood cell transfusion at 24 hours postoperatively (19 [15.8%] vs. 14 [13.1%] p = 0.69). Those in the model group had a lower median protamine dose (180 [IQR 160–210] vs. 280 [IQR 250–300] mg; p < 0.001). Important limitations of this study include an unblinded design and lack of generalisability to certain populations deliberately excluded from the study (specifically children, patients with a total body weight >120 kg, and patients requiring therapeutic hypothermia to <28°C). Conclusions Using a mathematical model to guide protamine dosing in patients following CPB improved TEG r-time and reduced the dose administered relative to a fixed ratio. No differences were detected in postoperative mediastinal/pleural drainage or red blood cell transfusion requirement in our cohort of low-risk patients. Trial registration ClinicalTrials.gov Unique identifier NCT03532594.

Simple periprocedural precautions to reduce Doppler microembolic signals during AF ablation

Background Doppler microembolic signals (MES) occur during atrial fibrillation ablation despite of permanent flushed transseptal sheaths, frequent controls of periprocedural coagulation status and the use of irrigated ablation catheters Purpose To investigate the number and type of MES depending on the procedure time, prespecified procedure steps, the activated clotting time (ACT) during the ablation procedure and the catheter contact force. Methods In a prospective trial, 53 consecutive atrial fibrillation patients underwent pulmonary vein isolation by super-irrigated “point-by-point” ablation. All patients underwent a periinterventional, continuous transcranial Doppler examination (TCD) of the bilateral middle cerebral arteries during the complete ablation procedure. Results An average of 686±226 microembolic signals were detected by permanent transcranial Doppler. Thereby, 569±208 signals were differentiated as gaseous and 117±31 as solid MES. The number of MES with regard to defined procedure steps were as follows: gaseous: [transseptal puncture, 26 ± 28; sheath flushing, 24±12; catheter change, 21±11; angiography, 101±28; mapping, 9±9; ablation, 439±192; protamine administration, 0±0]; solid: [transseptal puncture, 8±8; sheath flushing, 9±5; catheter replacement, 6±6; angiography, not measurable; mapping, 2±5; ablation, 41±22; protamine administration, 0±0]. Significantly less MES occurred with shorter procedure time, higher ACT and the use of tissue contact force monitoring. Conclusion The current study demonstrates that during atrial fibrillation ablation using irrigated, “point-by-point” RF ablation, masses of microembolic signals are detected in transcranial ultrasound especially in the period of RF current application. The number of MES depends on the total procedure time and the reached ACT during ablation. The use of contact force monitoring might reduce MES during RF ablation.

Antithrombotic Therapy in Chronic Total Occlusion Interventions

Chronic total occlusion (CTO) recanalization is among the most complex subsets of coronary interventions. Hence, optimum peri- and post-procedural anticoagulation and antiplatelet therapy is key for the achievement of successful revascularization and reduction of major adverse cardiovascular outcomes in patients undergoing CTO percutaneous coronary intervention (PCI). Unfractionated heparin is still considered the gold standard anticoagulant because its action can be reversed by protamine administration, with bivalirudin being reserved mainly for patients with heparin-induced thrombocytopenia. However, small studies comparing unfractionated heparin with bivalirudin in CTO interventions have shown similar outcomes. Glycoprotein IIb/IIIa inhibitors should, in general, be avoided. Aspirin in combination with clopidogrel for 6–12 months is the standard post CTO PCI dual antiplatelet regimen. For the most complex cases, clopidogrel can be substituted by a more potent P2Y12 inhibitor, namely ticagrelor or prasugrel.

An Exploratory, Observational Cohort Study on the Dynamics of Heparin Binding Protein in Cardiothoracic Surgery Using Cardiopulmonary Bypass

BackgroundSurgical trauma and cardiopulmonary bypass (CPB) cause an inflammatory response, difficult to differentiate from postoperative infections. Heparin-binding protein (HBP) is released from neutrophils and has been shown to predict infection-related organ dysfunction and disease progression to severe sepsis. In order to explore the potential of HBP as a biomarker for postoperative infections and asess possible confounding effects of concomitant medications, this study aimed to investigate the pre-, intra- and postoperative dynamics of HBP in cardiac surgery with CPB.Methods Thirty patients undergoing cardiac surgery with CPB were included, of which 15 underwent coronary artery bypass grafting (CABG) surgery and 15 underwent complex procedures with longer CPB duration. Ten patients undergoing lung surgery without CPB were also included as a conventional surgery reference group. HBP was measured at nine different perioperative time points.Results Our results showed that HBP levels were not affected by surgical trauma by itself. An increase in HBP levels was observed immediately following heparin administration and further increased during CPB. Prior to protaminization, we measured higher peak HBP-levels in the complex group (345.7 (287.8-472.6) ng/mL) compared with the CABG group (152.7 (85.3-204.0) ng/mL, p<0.001). HBP decreased rapidly following cessation of CPB and simultaneous protamine administration. Delay of protamine administration revealed that protamine, and not the cessation of CPB is primarily responsible for the rapidly reduced HBP concentration. At the arrival to the ICU, the median HBP levels were 24.8 (15.6-38.1) ng/mL for CABG patients compared with 50.5 (36.5-104.6) ng/mL for complex surgery patients (p=0.004). One day after surgery, HBP levels in all three groups were below the proposed cutoff of 30 ng/mL, previously found to predict development of organ dysfunction during infection, while other biomarkers for infections remained elevated.ConclusionsHBP levels are elevated by administration of heparin and the use of CPB but reduced by protamine administration. At postoperative day one, HBP levels were below the threshold for infection with organ dysfunction, indicating that postoperative HBP measurement may be a better screening tool for postoperative infections than other biomarkers of infections that remain elevated after surgery.

Anticoagulation management during pulmonary endarterectomy with cardiopulmonary bypass and deep hypothermic circulatory arrest

Introduction: Pulmonary endarterectomy requires cardiopulmonary bypass and deep hypothermic circulatory arrest, which may prolong the activated clotting time. We investigated whether activated clotting time–guided anticoagulation under these circumstances suppresses hemostatic activation. Methods: Individual heparin sensitivity was determined by the heparin dose–response test, and anticoagulation was monitored by the activated clotting time and heparin concentration. Perioperative hemostasis was evaluated by thromboelastometry, platelet aggregation, and several plasma coagulation markers. Results: Eighteen patients were included in this study. During cooling, tube-based activated clotting time increased from 719 (95% confidence interval = 566-872 seconds) to 1,273 (95% confidence interval = 1,136-1,410 seconds; p < 0.01) and the cartridge-based activated clotting time increased from 693 (95% confidence interval = 590-796 seconds) to 883 (95% confidence interval = 806-960 seconds; p < 0.01), while thrombin–antithrombin showed an eightfold increase. The heparin concentration showed a slightly declining trend during cardiopulmonary bypass. After protamine administration (protamine-to-heparin bolus ratio of 0.82 (0.71-0.90)), more than half of the patients showed an intrinsically activated coagulation test and intrinsically activated coagulation test without heparin effect clotting time >240 seconds. Platelet aggregation through activation of the P2Y12 (adenosine diphosphate test) and thrombin receptor (thrombin receptor activating peptide-6 test) decreased (both −33%) and PF4 levels almost doubled (from 48 (95% confidence interval = 42-53 ng/mL) to 77 (95% confidence interval = 71-82 ng/mL); p < 0.01) between weaning from cardiopulmonary bypass and 3 minutes after protamine administration. Conclusion: This study shows a wide variation in individual heparin sensitivity in patients undergoing pulmonary endarterectomy with deep hypothermic circulatory arrest. Although activated clotting time–guided anticoagulation management may underestimate the level of anticoagulation and consequently result in a less profound inhibition of hemostatic activation, this study lacked power to detect adverse outcomes.

P451Optimizing the EP lab workflow in atrial fibrillation ablation - The use of Z stitch for groin access closure

Introduction As catheter ablation became the standard therapy for atrial fibrillation (AF), the number of AF procedures has risen exponentially. Therefore, workflow optimization is crucial in order to meet the rising demands for EP interventions. Recently, instead of standard groin compression we have started using the "Z stitch" for introducers’ removal. This novel method does not necessitate protamine administration and often lengthy manual compression. Purpose We aim to demonstrate utilization of "Z stitch" for groin access closure in cryoballoon (CB) ablation and its impact on EP lab workflow. Methods We have analyzed all patients having undergone CB ablation utilizing the "Z stitch" (Z group) and the last 50 consecutive CB patients who received standard groin compression (non-Z group). Procedures were performed under conscious sedation. Both femoral veins were punctured and a single introducer was placed in each vein. A single transeptal puncture was preformed guided by intracardial ultrasound and a 28 mm cryoballoon was used. A single 180 seconds freeze strategy was employed. In the past, protamine was slowly administered after ablation and at least 15 minute manual groin compression was applied until no visual bleeding could be detected. Elastic bandage was placed around both groins. Later on, the "Z stitch" was used around both introducers without the need for protamine administration, manual compression and bandage placement (Picture). The stitches were removed next morning. Results A total of 100 consecutive patients (79% male, 61.2 ± 10.6 years old) were evaluated, 50 in both groups. There was no difference in the mean procedure duration ("skin to skin") between two groups. However, a total lab time was significantly longer in non-Z group. There was no differences in complication rates, which consisted solely of phrenic nerve palsy and groin complications. There was no AV fistula or pseudoaneurysms detected in our cohort (Table). Conclusion Utilization of Z stitches for introduces’ removal seems safe and effective way to achieve hemostasis after cryoballoon ablation. It abolishes the need for protamine administration which can cause serious advert events. Manual compression is no longer required. Consequently, EP lab workflow is improved, since the total lab time utilization per patient is significantly shortened. Results non-Z group Z group p Procedure duration (min) 69.4 ± 20.4 73.4 ± 24.8 0.380 Lab time (min) 129.9 ± 35.3 109.1 ± 30.6 0.002 Complications (N) 5 (2 hematoma) 4 (2 hematoma) NS Abstract Figure. Z stich