Rashad Zayat

Ultrasound-assisted treatment of sternocutaneous fistula in post-sternotomy cardiac surgery patients

OBJECTIVES Using an ultrasonic debridement system (low frequency, 25 kHz), we aimed to completely remove bacterial biofilms and preserve vital sternal tissue and to compare this procedure with conventional surgical therapy. METHODS In this retrospective study, we evaluated 37 consecutive patients (25 males) between April 2011 and June 2013 in whom sternocutaneous fistula (SCF) was treated with the ultrasound-assisted wound (UAW) system (Group A, n = 18) or with conventional surgical therapy (Group B, n = 19). Treatment in Group A consisted of a complete dissection of the SCF followed by a multistep UAW debridement session after an interval of 3 days. Our final step in both groups was secondary wound closure with a musculocutaneous flap. RESULTS Patients in both groups were categorized as high risk with respect to several of the known SCF risk factors. In both groups, a similar variety of bacteria were isolated: 61% were gram-positive species, 16.5% were gram-negative species and 10.5% were Candida albicans. Time to secondary wound closure following eradication was significantly shorter in Group A (10 ± 5.4 vs 15 ± 7.1 days in Group B, P = 0.012). Postoperative antibiotic treatment time (16 ± 9.3 vs 22 ± 10.7 days in Group B, P = 0.078) showed a trend in favour of Group A, but the mean hospitalization time (22 ± 12.0 vs 26 ± 14.3 days in Group B, P = 0.34) did not differ between groups. Recurrence of SCF tended to be less frequent in Group A (6 vs 21% in Group B, P = 0.46). In Group B, one infection-related death was noted. The mean follow-up time was 8 ± 2.7 (Group A) and 10 ± 5.7 (Group B) months. CONCLUSIONS Ultrasonic debridement is a promising adjunct to SCF treatment. In combination with adequate surgical and antimicrobial therapy, we documented good mid-term results in our trial group.

Comparison between radial artery tonometry pulse analyzer and pulsed-Doppler echocardiography derived hemodynamic parameters in cardiac surgery patients: a pilot study

Background Bedside non-invasive techniques, such as radial artery tonometry, to estimate hemodynamic parameters have gained increased relevance as an attractive alternative and efficient method to measure hemodynamics in outpatient departments. For our pilot study, we sought to compare cardiac output (CO), and stroke volume (SV) estimated from a radial artery tonometry blood pressure pulse analyzer (BPPA) (DMP-Life, DAEYOMEDI Co., Gyeonggi-do, South Korea) to pulsed-wave Doppler (PWD) echocardiography derived parameters. Methods From January 2015 to December 2016, all patients scheduled for coronary artery bypass (CABG) surgery at our department were screened. Exclusion criteria were, inter alia, moderate to severe aortic- or Mitral valve disease and peripheral arterial disease (PAD) > stage II. One hundred and seven patients were included (mean age 66.1 ± 9.9, 15 females, mean BMI 27.2 ± 4.1 kg/m2). All patients had pre-operative transthoracic echocardiography (TTE). We measured the hemodynamic parameters with the BPPA from the radial artery, randomly before or after TTE. For the comparison between the measurement methods we used the Bland-Altman test and Pearson correlation. Results Mean TTE-CO was 5.1 ± 0.96 L/min, and the mean BPPA-CO was 5.2 ± 0.85 L/min. The Bland-Altman analysis for CO revealed a bias of −0.13 L/min and SD of 0.90 L/min with upper and lower limits of agreement of −1.91 and +1.64 L/min. The correlation of CO measurements between DMP-life and TTE was poor (r = 0.501, p < 0.0001). The mean TTE-SV was 71.3 ± 16.2 mL and the mean BPPA-SV was 73.8 ± 19.2 mL. SV measurements correlated very well between the two methods (r = 0.900, p < 0.0001). The Bland-Altman analysis for SV revealed a bias of −2.54 mL and SD of ±8.42 mL and upper and lower limits of agreement of −19.05 and +13.96 mL, respectively. Conclusion Our study shows for the first time that the DMP-life tonometry device measures SV and CO with reasonable accuracy and precision of agreement compared with TTE in preoperative cardiothoracic surgery patients. Tonometry BPPA are relatively quick and simple measuring devices, which facilitate the collection of cardiac and hemodynamic information. Further studies with a larger number of patients and with repeated measurements are in progress to test the reliability and repeatability of DMP-Life system.

Perioperative onset of acquired von Willebrand syndrome: Comparison between HVAD, HeartMate II and on-pump coronary bypass surgery

Objectives Acquired von Willebrand syndrome (AvWS) is associated with postoperative bleeding complications in patients with continuous flow left ventricular assist devices (CF-LVADs). The aim of this study is to analyze the perioperative vWF profile comparing an axial pump (HMII) to a centrifugal pump (HVAD) regarding the correlation between perioperative occurrence of AvWS, early- and late-postoperative bleeding events. Methods From July 2013 until March 2015 blood samples of 33 patients (12 HMII/ 8 HVAD/ 13 controls) were prospectively collected at 12 different time points and analyzed for the vWF antigen (vWF:Ag), its activity (vWF:Ac) and the vWF:Ac/vWF:Ag-ratio (vWF:ratio). The follow up period for postoperative bleeding events was from July 2013 until July 2016. Results Postoperatively, there was no difference in the vWF-profile between HVAD and HMII groups. However, a subgroup of patients already had significantly lower vWF:ratios preoperatively. Postoperatively, both CF-LVAD groups presented significantly lower vWF:ratios compared to the control group. Bleeding events per patient-year did not differ between the two groups (HMII vs. HVAD: 0.67 vs. 0.85, p = 0.685). We detected a correlation between vWF:ratio <0.7at LVAD-start (r = -0.583, p = 0.006) or at the end of surgery (r = -0.461, p = 0.035) and the occurrence of pericardial tamponade. In the control group, the drop in both vWF:Ag and vWF:Ac recovered immediately postoperatively above preoperative values. Conclusion A subgroup of patients with end-stage heart failure already suffers AvWS preoperatively. In both CF-LVAD groups, AvWS begins immediately after surgery. Intraoperative vWF:ratios <0.7 correlate with higher incidences of pericardial tamponade and re-operation. The presumably dilutive effect of the heart lung machine on vWF vanishes immediately at the end of surgery, possibly as part of an acute-phase response.

Risk factors for the development of right ventricular failure after left ventricular assist device implantation—a single-centre retrospective with focus on deformation imaging

OBJECTIVES Right heart failure (RHF) after the implantation of a left ventricular assist device (LVAD) remains a dreaded postoperative complication. Using 2D speckle-tracking echocardiography, it is possible to acquire right ventricular global and regional function. The aim of our study was to assess whether speckle-tracking echocardiography values will better predict the RHF post-continuous-flow LVAD implantation. METHODS From January 2014 to January 2016, 54 patients who underwent LVAD implantation were included and retrospectively analysed. Clinical, invasive haemodynamic (right and left heart catheterization), laboratory and transthoracic echocardiography data were reviewed. Multivariable logistic regression was performed using RHF as dependent variable. RESULTS Thirteen patients (24%) developed RHF. These patients had significantly elevated procalcitonin (P = 0.011), elevated central venous pressure (CVP) pre- and post-LVAD implantation (P = 0.002 and 0.031, respectively), higher right ventricular (RV) and pulmonary systolic pressure (P = 0.016 and 0.013, respectively), higher Michigan Risk Score (P = 0.001) and a lower peak systolic longitudinal strain of the basal RV free wall (P = 0.032). Haemoglobin, procalcitonin, RV systolic pressure, basal right ventricular free wall and pre-CVP entered the final multivariable analysis, only basal right ventricular free wall (P < 0.001) and pre-CVP (P < 0.001) remained significant predictors of RHF. The sensitivity and specificity of the final model were 85.7% and 95.4%, respectively. The negative predictive value reached 94%. CONCLUSIONS 2D strain parameters of the RV free wall seem to be auspicious for RV function and predicting RHF. Moreover, intraoperative CVP should not be neglected since elevated values proved to be highly associated with RHF. Our results represent a valuable supplement to other scores by considering both echocardiography and intraoperative data.

In vitro comparison of the hemocompatibility of EVAHEART and HeartMate 3

Objectives Shear stress from left ventricular assist devices induces von Willebrand factor degradation and platelet dysfunction, leading to nonsurgical bleeding. We characterized the hemostatic changes induced by 2 centrifugal left ventricular assist devices, the HeartMate 3 (Abbott Inc, Chicago, Ill) and the EVAHEART (Evaheart Inc, Houston, Tex), for comparison. Methods Whole blood from 8 healthy volunteers was used ex vivo. Blood from the same donor was used for 6 hours of circulation in a miniature mock‐loop system consisting of 2 identical extracorporeal circuits to compare the following experimental settings: (1) optimal revolutions per minute (rpm) for the HeartMate 3 (n = 4; 5000 rpm) and the EVAHEART (n = 4; 2500 rpm) and (2) equal rpm (3000 rpm for the HeartMate 3 and EVAHEART, n = 4 vs n = 4). For both settings, blood flow was adjusted to 1 mock‐loop filling volume per minute (HeartMate 3 = 82 mL/min, EVAHEART = 100 mL/min). A panel of coagulation markers was analyzed to investigate hemostatic changes. Results The free plasma hemoglobin concentration was significantly lower in the EVAHEART compared with the HeartMate 3 after 6 hours of mock‐loop circulation under both settings (optimal: 37 ± 31 vs 503 ± 173 mg/dL, P < .0001; equal: 27 ± 4 vs 139 ± 135 mg/dL, P = .024). Loss of von Willebrand factor high‐molecular‐weight multimers occurred in both left ventricular assist devices and settings, but the von Willebrand factor:activity/von Willebrand factor:antigen ratio after 6 hours was significantly lower in optimal settings for the HeartMate 3 (P = .009). The thrombin‐antithrombin complex level was significantly lower with the EVAHEART for both settings (P < .0001). Conclusions The EVAHEART left ventricular assist device caused less hemolysis, resulted in lower coagulation activation, and provided better preservation of von Willebrand factor functional activity compared with the HeartMate 3 device. These findings prove that left ventricular assist device design plays a major role in minimizing blood damage during left ventricular assist device support. Graphical abstract Figure. No Caption available.

Sildenafil Reduces the Risk of Thromboembolic Events in HeartMate II Patients with Low-Level Hemolysis and Significantly Improves the Pulmonary Circulation

Low-level hemolysis (LLH) after left ventricular assist device implantation contributes to thromboembolic events (TE). Free plasma hemoglobin (fHb) scavenges nitric oxide (NO), which causes endothelial dysfunction and activates platelets. fHb also interacts with von Willebrand factor (vWF). We hypothesized that improved hemodynamic and enhanced NO signaling in HeartMate II (HMII) patients with LLH taking the phosphodiesterase-5 inhibitor sildenafil may reduce the risk of TE.From 2011 to 2015, 83 patients underwent HMII implantation. Patients with LLH as defined by elevated lactate dehydrogenase (400 < LDH ≤ 700 U/L) at hospital discharge were identified. Patients were categorized into 4 groups: 1) LLH + sildenafil, 2) LLH no sildenafil, 3) no LLH + sildenafil, and 4) no LLH no sildenafil. Adverse event-free survival was compared between the groups.Thirty-four patients (40.9%) were discharged with LLH and 22 (64.7%) of them took sildenafil. LDH and fHb remained significantly elevated in both LLH groups compared to the no LLH patients (P < 0.0001). Overall incidence of pump thrombosis (PT) was 4.8% and of ischemic stroke (IS) was 8.4%. HMII patients with LLH not on sildenafil had higher risk of TE (hazard ratio (HR): 14.4, 95%-CI: 1.8-117.1, P = 0.001). vWF activity and bleeding incidence did not differ between the LLH and no LLH patients. Mean pulmonary artery pressure and pulmonary vascular resistance decreased significantly in HMII taking sildenafil (P < 0.0001) while cardiac index increased (P < 0.0001).Sildenafil treatment among HMII patients with LLH reduced the risk of thromboembolic events and significantly improved and decompressed the pulmonary circulation during HMII support.

In vitro head-to-head comparison of anticoagulation properties of two heparin brands in a human blood miniature mock loop

OBJECTIVES The first aim was the development of a human blood miniature mock-loop system consisting of 2 identical extracorporeal circuits, which enable systematic head-to-head comparisons of test substances. In a second step, we evaluated the suitability of the mock-loop system, by comparing 2 different brands of heparin (ROTEXMEDICA vs B.BRAUN), which have showed different anticoagulation capacities in the clinic. METHODS For 1 experiment (18 in total), blood of the same healthy human donor was divided into 2 portions (2 × 50 ml), heparinized with 37.5 IU⋅ml-1 of the competing test substances and diluted to a haematocrit value of 20-25%. Each mock loop was filled with 70 ml, and in vivo heparin degradation was simulated in 3 different groups by protamine application, representing 0%, 50% and 100% heparin antagonization. At baseline, 5, 60, 120, 240 and 360 min, blood samples were taken to perform thromboelastometry, flow cytometry, haemolysis and general haemostasis analysis. RESULTS Blood pressure, blood flow and blood temperature within the loops remained stable for 6 h in all groups. After 6 h, in the 100% antagonized ROTEXMEDICA heparin group, significantly increased haemolysis (148.7 ± 80 mg⋅dl-1 vs 57.5 ± 15.8 mg⋅dl-1), activated platelets (8 ± 3.8% vs 3.3 ± 0.7%), D-dimers (7376 ± 7144 ng ml-1 vs 576.2 ± 190 ng ml-1) and fulminant blood clots were detected. CONCLUSIONS Our in vitro system is suitable for the detection of reduced anticoagulation capacity of a test drug, which was reported in vivo previously.

Are elevated serum haemolysis markers a harbinger of adverse events in HeartMate II patients

OBJECTIVES Haemolysis during left ventricular assist device support is associated with thrombosis. In this retrospective study, we analysed whether low-level haemolysis (LLH) as defined by simultaneously elevated lactate dehydrogenase (LDH) and free haemoglobin (fHb) levels had an impact on thromboembolic and bleeding events and on von Willebrand factor levels in HeartMate II patients. METHODS After exclusion of patients with LDH >700 U/l and fHb >40 mg/dl at hospital discharge, 79 HeartMate II patients were included. LDH and fHb levels were measured at discharge and in 3 months interval. von Willebrand factor activity and antigen activity were measured 3 months postoperatively. Outcomes regarding ischaemic stroke (IS), pump thrombosis (PT) and gastrointestinal bleeding were recorded. Patients with LLH (400 < LDH ≤ 700 U/l and 30 < fHb ≤ 40 mg/dl) at discharge (pre-Hemolyzers) were compared with the rest of the cohort (non-Hemolyzers). Competing risk analysis and Cox regression were applied for the comparison between groups. RESULTS In all, 20% of the patients were identified as pre-Hemolyzers. Of these, 5 patients had PT and 3 patients had IS compared with 2 PT and 2 IS in the non-Hemolyzers group (P = 0.003 and P = 0.053, respectively). Fifty percent of the pre-Hemolyzers suffered gastrointestinal bleeding compared with 42% of the non-Hemolyzers (P = 0.399). The cumulative risk of thromboembolic events (IS or PT) in the pre-Hemolyzers group was significantly higher compared with the non-Hemolyzers group (hazard ratio 11.8, 95% confidence interval 3.7-37.7; P = 0.005). LLH did not have an impact on von Willebrand factor and the incidence of gastrointestinal bleeding. CONCLUSIONS LLH as assessed by elevated fHb and LDH values at discharge during HeartMate II support is associated with thromboembolic events.

Synchronous or Staged Carotid Endarterectomy and Coronary Artery Bypass Grafting? Propensity score matched study

BACKGROUND The optimal treatment strategy in patients presenting with hemodynamically significant carotid artery disease who are to undergo cardiac surgery, remains controversial. In this study, we retrospectively analyzed the outcome data of patients receiving synchronous or staged coronary artery bypass graft (CABG) surgery and carotid endarterectomy (CEA). METHODS Between 2011 and 2016, 3173 patients underwent CABG surgery in our institution, of whom 323 received CABG and CEA either as synchronous (N = 307) or as staged (N = 16) procedures. Patients´ characteristics, peri- and postoperative data were collected from our digital medical database. Propensity score matching was used to match each patient from the staged group to two appropriate patients (1:2 matching) from the synchronous group (synchronousmatched). RESULTS The overall incidence of ischemic stroke (IS) and transitory ischemic attack (TIA) was 4.9% and 5.6%, respectively. No hemorrhagic stroke was noted in both groups. Incidence of IS did not differ significantly between matched groups (P = 1.000). Significantly higher rates of postoperative neurological complications, such as TIA and delirium, were found in the synchronousmatched group (P = .041 and P = .043, respectively) compared with the staged group. Additionally, there were more postoperative respiratory insufficiencies in the synchronousmatched group (P = .043). Thirty days mortality did not differ significantly between the matched groups. CONCLUSION In this experience combined with the data given in literature, our findings suggest a possible superiority of the staged CABG/CEA approach. Large, randomized studies are required to verify our findings and to establish applicable guidelines.

Is Systolic Right Ventricular Function Reduced after Thoracic Non-Cardiac Surgery? A Propensity Matched Echocardiographic Analysis

Purpose: To assess whether thoracic non-cardiac surgery has an influence on right ventricular function (RVF) compared to known impaired postoperative RV function after cardiac surgery. Methods: In all, 50 patients (mean age: 61 years), who underwent thoracic non-cardiac surgery were included and matched using propensity score to 50 patients, receiving coronary artery bypass graft surgery (CABG) (CABGmatched). All patients had transthoracic echocardiography (TTE) including two-dimensional speckle tracking (2D-STE) and tissue Doppler imaging (TDI) pre- and 1 week postoperatively. Results: No significant changes in RV measurements including tricuspid annular plane systolic excursion (TAPSE), tricuspid annular systolic velocity (TASV), RV fractional area change (RV-FAC), and 2D-STE of the RV and RV freewall within the thoracic non-cardiac surgery patients comparing pre- and postoperative values. Comparing RV TTE values between CABGmatched patients and thoracic surgery patients, only TAPSE differed between groups preoperatively (p <0.0001), where postoperatively, all RV measurements differed significantly between the two groups: TAPSE (p <0.0001), TASV (p <0.001), RVFAC (p = 0.005), and RV 2D-STE (p <0.0001) indicating impairment of RV function post-CABG surgery compared to thoracic non-cardiac surgery. Conclusion: Thoracic non-cardiac surgery including an opening of the pleural cavity did not influence RV function early postoperative, whereas CABG surgery with pericardiotomy led to an impaired global RV function.