Marek Pojar

Impact of cardiopulmonary bypass on peripheral tissue metabolism and microvascular blood flow.

The aim of this study was to monitor and compare the changes in metabolism and blood flow in the skeletal muscles during cardiac operations performed with cardiopulmonary bypass (CPB) and operations without CPB (off-pump) by means of interstitial microdialysis (Figure 1). Surgical revascularization, coronary artery bypass grafting (CABG), was performed in 40 patients randomized to two groups. Twenty patients (On-Pump Group) were operated on using CPB, 20 patients (Off-Pump Group) were operated on without CPB. Interstitial microdialysis was performed by 2 probes of a CMA 60 (CMA Microdialysis AB, Solna, Sweden) inserted into the patient’s deltoid muscle. Microdialysis measurements were performed at 30-minute intervals. Glucose, lactate, pyruvate and glycerol as markers of basic metabolism and tissue perfusion were measured in samples from the first probe, using a CMA 600 Analyzer (CMA Microdialysis AB). Blood flow through the interstitium was monitored by means of dynamic microdialysis of ethanol as a flow-marker in the dialysates taken from the second probe (ethanol dilution technique). Results in both the groups were statistically processed and compared. Both the groups were similar in respect of preoperative characteristics. Dynamic changes of interstitial concentrations of the measured analytes were found in both the patient groups (on-pump vs. off-pump) during the operation. There was no significant difference in dialysate concentrations of glucose and lactate between the groups. Significant differences were detected in pyruvate and glycerol interstitial concentrations, lactate/pyruvate ratio and lactate/glucose ratio between the on-pump vs. off-pump patients. In the Off-Pump Group, pyruvate concentrations were higher and the values of concentrations of glycerol lower. The lactate/pyruvate ratio and the lactate/glucose ratio, indicating the aerobic and anaerobic tissue metabolism status, were lower in the Off-Pump Group. There was no significant difference in dialysate concentrations of ethanol as a flow-marker during the surgery in either of the groups. There was no statistically significant difference between the groups (On-Pump Group vs. Off-Pump Group) comparing the postoperative clinical outcome (ICU stay, ventilation duration, length of hospital stay). The dynamic changes in the interstitial concentrations of the glucose, glycerol, pyruvate and lactate were found in both the groups of patients (On-Pump Group and Off-Pump Group), but there was no difference in local blood flow when the ethanol dilution technique was used. These results showed significantly higher aerobic metabolic activity of the peripheral tissue of patients in the Off-Pump Group vs. the On-Pump Group during the course of cardiac revascularization surgery. Results suggest that extracorporeal circulation, cardiopulmonary bypass, compromises peripheral tissue (skeletal muscles) energy metabolism. These changes have no impact on the postoperative clinical outcome; no significant difference between the groups was found.

Tissue and plasma concentrations of cephuroxime during cardiac surgery in cardiopulmonary bypass — a microdialysis study

Aim: Wound and mediastinal infections are still very serious complications of open-heart surgery, in spite of the use of prophylactic antibiotics. The use of cardiopulmonary bypass (CPB) is associated with profound physiological changes affecting the pharmacokinetic behaviour of antibiotics. The aim of this pilot study was to monitor the tissue concentrations of cephuroxime (prophylactic antibiotic) in skeletal muscle during cardiac surgery using CPB by interstitial microdialysis. These concentrations were compared with plasma concentrations of cephuroxime. Material and methods: Nine adult patients operated on using CPB were enrolled in this study. Cephuroxime was used as a prophylactic antibiotic (1st dose — 3 g of cefuroxime i.v. with anesthesia induction, 2nd dose — 1.5 g i.v. after CPB with protamine sulphate, 3rd dose — 1.5 g i.v. 8 hours after the surgery). Interstitial microdialysis was performed by probe CMA 60 (CMA Microdialysis AB, Sweden) inserted into the patients deltoid muscle. Concentrations of cephuroxime in dialysates and in plasma were determined by the modified fluid chromatography method. The unbound cephuroxime fraction in plasma was obtained by using an ultrafiltration method. Samples of dialysates were collected at the following intervals: before CPB, each 30 minutes of CPB, at the end of CPB. Samples of blood were collected at these intervals: incision, start of CPB, each 30 minutes of CPB, at the end of CPB, at the end of surgery. Concentrations of cephuroxime in tissue were corrected by in vivo recoveries of the microdialysis probes. Results: Plasma concentrations of cephuroxime were 163.5 ± 40.1, 79.3 ± 17.4, 73.7 ± 16.8, 66.1 ± 18.3, 57.0 ± 10.9, 120.7 ± 29.9 (mg . L — 1) and concentrations of free plasma fraction of cephuroxime were 119.5 ± 35.2, 67.8 ± 15.5, 66.0 ± 12.5, 54.8 ± 12.2, 49.6 ± 9.8, 102.6 ± 26.0 (mg . L — 1). The concentrations of cephuroxime in dialysates were 44.3 ± 15.7, 36.1 ± 11.6, 31.9 ± 9.3, 34.6 ± 12.3, 27.6 ± 12.9, 56.7 ± 17.6 (mg . L — 1). The mean in vivo recovery of cephuroxime in this study was 30%. Corrected concentrations (calculated by in vivo recovery) of cephuroxime in skeletal muscle were 148, 120, 106, 115, 92, 189 (mg . L — 1). Conclusion: Our preliminary results show that CPB can modify the time course of cephuroxime plasma and tissue concentrations. A decrease in plasma drug concentrations occurred at the start of CPB and lasted until CPB ended. An increase in plasma concentrations corresponds to the second drug dose after CPB. The concentrations of cephuroxime in skeletal muscle (corrected by recovery) during CPB are higher than plasma concentrations. It is influenced by important changes during CPB; closely associated with hemodilution, a shift of intravascular volume, solutes and albumin to the extravascular space and inconstant protein binding of cephuroxime during operation. Perfusion (2007) 22, 129—136.

Peripheral tissue metabolism during off-pump versus on-pump coronary artery bypass graft surgery: the microdialysis study.

OBJECTIVE The aim of this study was to monitor and compare metabolic changes in the skeletal muscle during coronary artery bypass grafting surgery with and without cardiopulmonary bypass (CPB) by means of interstitial microdialysis. Glucose, lactate, pyruvate and glycerol were assessed as markers of basic metabolism and tissue perfusion. METHODS Twenty patients undergoing surgical myocardial revascularization were enrolled in this pilot study. Ten patients were operated on without CPB (group A, off-pump) and 10 patients using normothermic CPB (group B, on-pump). Interstitial microdialysis was performed by a CMA 60 (CMA/Microdialysis AB, Sweden) probe, inserted into the patients left deltoid muscle. Microdialysis measurements were performed at 30 min intervals. Glucose, lactate, pyruvate and glycerol were measured in samples using a CMA 600 Analyser (CMA/Microdialysis AB, Sweden). Results in both groups were statistically processed and the groups were compared. RESULTS Both groups were similar with regards to preoperative characteristics. Dynamic changes of interstitial concentrations of the measured analytes were found in off-pump (group A) and on-pump (group B) patients during the operation. There were no significant differences in dialysate concentrations of glucose and lactate between the groups. Significant differences were detected in pyruvate concentrations, lactate-pyruvate ratio and glycerol concentrations between off-pump versus on-pump patients. Pyruvate concentrations were higher in the off-pump group (p<0.05), the lactate-pyruvate ratios indicating the aerobic/anaerobic metabolism status were lower in the off-pump group (p<0.01) and the values of the concentrations of glycerol were lower in the off-pump group (p<0.01). CONCLUSION Dynamic changes in the interstitial concentrations of the glucose, glycerol, pyruvate and lactate were found in both groups of patients (off-pump and on-pump). The presented preliminary results suggest that extracorporeal circulation during cardiac operations could compromise skeletal muscle energy metabolism.

Thoracoscopic Radiofrequency Ablation for Lone Atrial Fibrillation: Box‐Lesion Technique

We report the feasibility and outcomes of box‐lesion ablation technique to treat stand‐alone atrial fibrillation (AF).

Left Hemothorax: An Unusual Complication of Delayed Right Ventricular Perforation by a Permanent Pacemaker Lead

Cardiac ventricle perforation by a pacemaker (PM) lead is an uncommon complication of PM implantation. We report a patient with a delayed right ventricular perforation from a permanent PM lead which presented as a left hemothorax. doi: 10.1111/jocs.12080 (J Card Surg 2013;28:325–327)

Surgical Cryoablation of Drug Resistant Ventricular Tachycardia and Aneurysmectomy of Postinfarction Left Ventricular Aneurysm

Heart failure is usually associated with left ventricle remodelling, wall thickening, and worsening of the systolic function. Ventricular tachycardia is a common and a negative prognostic factor in patients with endocardial scarring following myocardial infarction and aneurysm formation. The authors present a case of a 51-year-old man with ischemic heart disease, who suffered myocardial infarction four years ago. The patient was admitted to the hospital with sustained ventricular tachycardia despite maximal pharmacotherapy and also underwent unsuccessful percutaneous radiofrequency ablation in the right ventricle. Transthoracic echocardiography revealed left ventricle dysfunction with ejection fraction of 25%, aneurysm of the apex of the left ventricle with thrombus formation inside the aneurysm. Surgical therapy consisted of the cryoablation applied at the transitional zone of the scar and viable tissue and the resection of the aneurysm. The patient remained free of any ventricular tachycardia four months later.

Surgical treatment of postinfarction ventricular septal defect: risk factors and outcome analysis

OBJECTIVES Postinfarction ventricular septal defect is a serious mechanical complication of acute myocardial infarction associated with high postoperative mortality. The aim of this study was to review our experience with surgical repair of postinfarction ventricular septal defect and to identify predictors of early and late outcomes. METHODS Thirty-nine patients (19 men and 20 women, mean age 68.4 ± 9.9 years) with postinfarction ventricular septal defect who underwent surgical repair at our institution between 1996 and 2016 were retrospectively evaluated. Risk factors were assessed by univariate analysis, with those found significant included in multivariate analysis. RESULTS The ventricular septal defect was anterior in 21 (54%) patients and posterior in 18 (46%) patients. Mean aortic cross-clamp time was 91.8 ± 26.8 min, and mean cardiopulmonary bypass time was 146.3 ± 49.7 min. Twelve (31%) patients underwent concomitant coronary artery bypass grafting. The 30-day mortality rate was 36% (n = 14). The 30-day survival rate was higher with than without concomitant coronary artery bypass grafting (83% vs 56%), but concomitant coronary artery bypass grafting did not influence late survival (P = 0.098). Univariate analysis identified age, emergency surgery, inotropic support, Killip class, preoperative aspartate aminotransferase concentration, renal replacement therapy and ventricular septal defect diagnosis to operation interval as predictors of 30-day mortality. However, multivariate analysis showed that age and renal replacement therapy were the only independent risk factors of 30-day mortality. CONCLUSIONS Surgical repair of postinfarction ventricular septal defect has a high 30-day mortality rate. Higher age at presentation and postoperative renal replacement therapy are independent predictors of early mortality.

Midterm outcomes of mini-invasive surgical and hybrid ablation of atrial fibrillation

BACKGROUND We evaluated the feasibility and effectiveness of thoracoscopic and a staged surgical and transcatheter ablation technique to treat stand-alone atrial fibrillation (AF). METHODS . Between 2009 and 2016, a cohort of 65 patients underwent bilateral totally thoracoscopic ablation of symptomatic paroxysmal AF (n=30; 46%), persistent AF (n=18; 28%) or long-standing persistent AF (n=17; 26%) followed by catheter ablation in case of AF recurrence. Surgical box lesion procedure included bilateral pulmonary vein and left atrial posterior wall ablation using irrigated bipolar radiofrequency with documentation of conduction block. RESULTS There were no intra- or peri-operative ablation-related complications. There was no operative mortality, no myocardial infarction, and no stroke. Skin-to-skin procedure time was 120.5 ± 22.0 min and the postoperative average length of stay was 8.1 ± 3.0 days. At discharge, 60 patients (92%) were in sinus rhythm. Median follow-up time was 866 days (IQR, 612-1185 days). One-year success rate after surgical procedure was 78% (off antiarrhythmic drugs). Eleven patients (17%) underwent catheter re-ablation. Sixty (92%) patients were free of atrial fibrillation after hybrid ablation (on demand) at 1 year follow up after the last ablation. The success at 24-months was achieved in 96% (paroxysmal) and 78% (persistent) patients. At the last follow-up control, 69% patients discontinued oral anticoagulant therapy. CONCLUSIONS . Combination of mini-invasive surgical and endocardial treatment (two-stage hybrid procedure) is a safe and effective method for the treatment of isolated (lone) AF. This procedure provided good midterm outcomes.

Single-Center Experience with Minimally Invasive Mitral Operations through Right Minithoracotomy

Background: To report single-institution experience with minimally invasive mitral valve operations through the right minithoracotomy over a 5-year period. Methods: Patients who underwent minimally invasive mitral valve surgery (MIMVS) between January 2012 and December 2016 were included. Clinical follow-up data were collected in a prospective database and analyzed retrospectively. Results: Data from 151 patients were assessed (mean age, 63.4 ± 9.7 years; 55% were females). Overall 30-day mortality was 0.7% (n = 1). Mean operating time, cardiopulmonary bypass, and aortic cross-clamp times were 254.9 ± 48.7, 140.5 ± 36.1, and 94.8 ± 27.0 minutes, respectively. Associated procedures were tricuspid valve annuloplasty (37.1%, n = 56) and closure of atrial septal defect (6.0%, n = 9). Cryoablation was performed in 43.7% of patients (n = 66). One patient (0.7%) required conversion to median sternotomy and six patients (4.0%) underwent re-explorations due to bleeding. Median postoperative hospital stay was 12 days. Overall survival at 5 years was 94.1% ± 2.0%. Freedom from reoperation was 94.6% ± 2.9% at 5 years. Conclusions: MIMVS is a feasible, safe, and reproducible approach with low mortality and morbidity. Mitral valve surgery through a small thoracotomy is a good alternative to conventional surgical access.

Penetrating aortic injury.

41-year-old man was referred to our department Abecause of sudden onset chest pain while using a lawn mower. Physical examination showed a penetrating chest injury of the left hemithorax. Chest computed tomography with contrast revealed a foreign body in the posterior mediastinum stuck between the thoracic descending aorta and the spine (Figs 1A, 1B, black arrows). A tangential thoracic aortic injury with intramural hematoma, caused by the foreign body, was evident. Considering the high probability of fatal aortic perforation, a stent graft was introduced into the thoracic descending aorta (Fig 1B, white arrow). After aortic wall stabilization by the implanted stent graft, the foreign body was extracted surgically from a left posterolateral thoracotomy, and a suture closed the penetrating canal in the left upper pulmonary lobe. The foreign body was an approximately 10-cm corroded wire (Fig 1C), which penetrated the chest wall and the anterior and the mediastinal aspect of the left upper pulmonary lobe and lodged in the posterior mediastinum. The patient recovered uneventfully. We believe that the wire got stuck in the lawn mower and was ejected as a projectile, causing a penetrating chest injury. This case demonstrates an uncommon cause of acute aortic syndrome, and also emphasizes the necessity of taking a multidisciplinary approach to such patients so an immediate and lifesaving intervention can be performed on time.