K. Hamouda

Cardiac surgery antibiotic prophylaxis and calculated empiric antibiotic therapy

Background Ongoing debate exists concerning the optimal choice and duration of antibiotic prophylaxis as well as the reasonable calculated empiric antibiotic therapy for hospital-acquired infections in critically ill cardiac surgery patients. Methods A nationwide questionnaire was distributed to all German heart surgery centers concerning antibiotic prophylaxis and the calculated empiric antibiotic therapy. Results The response to the questionnaire was 87.3%. All clinics that responded use antibiotic prophylaxis, 79% perform it not longer than 24 h (single-shot: 23%; 2 doses: 29%; 3 doses: 27%; 4 doses: 13%; and >5 doses: 8%). Cephalosporin was used in 89% of clinics (46% second-generation, 43% first-generation cephalosporin). If sepsis is suspected, the following diagnostics are performed routinely: wound inspection 100%; white blood cell count 100%; radiography 99%; C-reactive protein 97%; microbiological testing of urine 91%, blood 81%, and bronchial secretion 81%; procalcitonin 74%; and echocardiography 75%. The calculated empiric antibiotic therapy (depending on the suspected focus) consists of a multidrug combination with broad-spectrum agents. Conclusion This survey shows that existing national guidelines and recommendations concerning perioperative antibiotic prophylaxis and calculated empiric antibiotic therapy are well applied in almost all German heart centers.

Impact of diabetes mellitus on the contractile properties of the left and right atrial myofilaments

OBJECTIVES The incidence of diabetes mellitus in patients with ischaemic cardiomyopathy is increasing. To evaluate the impact of diabetes mellitus on contractility, we examined the calcium-induced force in left and right atrial myofilaments of patients with and without diabetes. METHODS We included 149 patients (106 without diabetes, 43 with diabetes), scheduled for elective coronary artery bypass grafting from August 2016 to June 2017. The left and right atria were excised and prepared for skinned fibre measurements (pCa-force curve). The unit for the force measurements is Millinewton (mN). Comprehensive demographic data as well as echocardiographic findings of the patients were collected. RESULTS We observed a significant decrease of left atrial force values in patients with diabetes, averaged over all calcium concentrations (patients with diabetes 0.50 ± 0.19 mN vs 0.68 ± 0.23 mN in patients without diabetes, P = 0.002) as well as in right atrial fibres (patients with diabetes 0.35 ± 0.17 mN vs 0.47 ± 0.21 mN in patients without diabetes, P = 0.005). There was a significant influence of repeated measurements (of the calcium concentrations) on force in left atrial myofilaments (P < 0.001). There was also a significant impact of diabetes on the force values of the different calcium concentrations in left atrial myofilaments (P 0.002). In right atrial myofilaments we also found a significant influence of repeated measurements (of the calcium concentrations) on force (P < 0.001). Additionally the impact of diabetes on the force values was significant (P = 0.005). CONCLUSIONS We demonstrated that diabetes mellitus has a significantly negative impact on calcium-induced force development in left and right atrial myofilaments.

Myofilament function and body mass index

Body mass is reported to influence myocardial performance. Recent studies have emphasised the importance of negative inotropic adipocyte-derived factors and their impact on cardiac contractile function. However, the underlying mechanisms remain unclear. We aimed to determine whether body mass impacts cardiac force development on the level of the contractile apparatus. We examined the influence of body mass index (BMI) (3 groups: group I >25, group II 25–30, group III >30) on the myocardial performance of skinned muscle fibres. Right atrial tissue preparations of 70 patients undergoing aortocoronary bypass operation (CABG, 48 patients, group a) and aortic valve replacement (AVR, 22 patients, group b) were obtained. The fibres were exposed to a gradual increase in the calcium concentration, and the force values were recorded. The statistical analysis was performed using Pearsons correlation (P<0.05 significant). A BMI >30 (group III) was associated with less force (mean force 1.58±0.1 mN, P=0.02, max force 2.24±0.17 mN, P=0.02 vs. group II (mean force 1.8±0.3 mN, P=0.04, max force 2.59±0.2 mN, P=0.03) and group I (mean force 1.8±0.1 mN, P=0,03, max force 2.62±0.3 mN, P=0.03). Dividing the groups in the post-surgical procedure, the impact of BMI on force development in group III was more intense in the CABG group compared to the AVR group: 2.0±0.2 mN vs. 2.4±0.1 mN, P=0.04. In accordance with the literature, a BMI >30 is associated with reduced force capacities. Additionally, the underlying cardiac disease may aggravate the impact of weight on cardiac force. Further studies are needed to evaluate the clinical relevance of this experimental observation and the potential consequences for the treatment of cardiac function.

How to Deal with a Porcelain Aorta in Combined Valve Surgery

Objectives: Cardiac surgery in patients scheduled for combined single/multiple valve and CABG surgery with undetected porcelain aorta is challenging. The aim of this retrospective study was to characterize patients who were treated with “no-touch technique” and additional replacement of the ascending aorta with hypothermic circulatory arrest addressing the porcelain aorta and identify determinants for clinical outcome. Methods: From 01/2008 to 04/2015, 29 patients (75.5 ± 8.2 years, EuroSCORE II 8.3; 95% CI: 5.5–15.8) with preoperatively undetected porcelain aorta and combined single/multiple valve and CABG surgery were observed. In all patients the ascending aorta was replaced using circulatory arrest. Factors influencing a combined endpoint (hospital mortality, stroke and prolonged ventilation) were evaluated. Results: The 30-day mortality was 6.9% (n = 2), Stroke occurred in 6.9% (n = 2), prolonged ventilation was necessary in 35% (n = 10). Summarized the combined endpoint was met by 12 individual patients. The combined endpoint was influenced by history of stroke, surgery of mitral and/or tricuspid valve surgery, BSA, creatinine clearance, LVEF, however, only BSA (p = 0.0019), creatinine clearance (p = 0.035) and LVEF (p = 0.024) reached statistical significance. Mean survival was 5.26 years (CI 95%: 4.16–6.36). One year and three year survival were 85.9 ± 6.5% and 75.6 ± 9.1%, respectively. Long-term survival was significantly influenced by the combined endpoint (p = 0.011). Conclusion: Although our data indicate that undetected porcelain aorta in complex cardiac surgery can be operated with good short and long-term results, better preoperative imaging in patients at risk for porcelain aorta could influence the treatment strategy and improve clinical outcome.

Degree of Carotid Artery Stenosis in Neurologically Asymptomatic Cardiac Surgical Patients Suffering from Perioperative Stroke: Results of an Observational Study

Background Postoperative stroke in cardiac surgical patients remains a serious adverse outcome. Methods A total of 2,784 consecutively operated cardiac surgical patients without preoperative neurologic impairment were analyzed retrospectively with regard to impact of preoperative carotid stenosis on the incidence of postprocedural new onset of stroke. Therefore, all analyzed patients were assigned to four groups depending on preoperative degree of carotid artery stenosis detected by carotid duplex sonography (group I: < 50%, group II: 50-75%, group III: 76-89%, and group IV: > 90%). Results All pre-, intra-, and postoperative risk factors for neurological disorders were comparable throughout the cohort. Of the 2,784 patients, 65 (2.3%) met the inclusion criteria (preoperatively neurologically asymptomatic status, preoperatively carotid duplex ultrasonography study not older than 6 months, heart surgery with extracorporeal circulation, stroke until 48 hours after operation). Of the 65 patients who met the inclusion criteria, 43 (66.2%) were in group I, 11 (16.9%) in group II, 5 (7.7%) in group III, and 6 (9.2%) in group IV (p = 0.175). The overall incidence of an ipsilateral stroke relating to the carotid stenosis was 38 (1.4%) patients. Of these, 27 (71.1%) patients were in group I, 6 (15.8%) patients in group II, 2 (5.3%) patients in group III, and 3 (7.9%) patients in group IV (p = 0.568). Conclusion This observational study demonstrates that the degree of carotid stenosis in neurologically asymptomatic cardiac surgical patients is not able to predict the probability of perioperative stroke. Until further results from prospective randomized trials with neurologically asymptomatic cardiac surgical patients are presented, a cautious attitude for concomitant carotid endarterectomy is still justified.

No touch technique and hypothermic circulatory arrest for porcelain aorta in combined valve surgery

Cardiac surgery in patients scheduled for combined single or multiple valve and CABG surgery with preoperatively undetected porcelain aorta is challenging. Different surgical strategies may address this problem. Abortion of the initial operation with subsequent interventional therapy and hypothermic circulatory arrest offer clampless treatment options in these patients.