Rainer Petzina

Negative pressure wound therapy for post-sternotomy mediastinitis reduces mortality rate and sternal re-infection rate compared to conventional treatment

OBJECTIVE Negative pressure wound therapy (NPWT) is a recently introduced treatment modality for post-sternotomy mediastinitis. The aim of this study was to compare the mortality rate, the sternal re-infection rate and the length of hospital stay in patients with post-sternotomy mediastinitis after NPWT and conventional treatment. METHODS We retrospectively analysed 118 patients with post-sternotomy mediastinitis after cardiac surgery. One group of 69 patients was treated with NPWT and the other group of 49 patients with conventional therapy. RESULTS There were no major differences between the two groups concerning preoperative data (EuroScore) or primary cardiac surgery (mainly coronary artery bypass grafting). NPWT therapy was found to reduce mortality rate (P=0.005) and sternal re-infection rate (P=0.008) compared with conventional treatment and tended to lead to a shorter length of hospital stay (P=0.08). CONCLUSIONS NPWT for post-sternotomy mediastinitis demonstrates encouraging clinical results with a reduction of the mortality rate and the sternal re-infection rate compared with conventional treatment. The results support NPWT as the first-line treatment for deep sternal wound infections.

Preventing heart injury during negative pressure wound therapy in cardiac surgery: assessment using real-time magnetic resonance imaging.

OBJECTIVE Heart rupture is a devastating complication to negative pressure wound therapy in cardiac surgery. Also, reduced cardiac output during negative pressure wound therapy has been reported. The present study aimed to examine the effects of negative pressure wound therapy on the position of the heart in relation to the thoracic wall using magnetic resonance imaging in a porcine sternotomy wound model. METHODS Six pigs had median sternotomy followed by negative pressure wound therapy at -75, -125, and -175 mm Hg. Real-time magnetic resonance imaging movies (10 images/s) were acquired in a midventricular transverse plane or a midsagittal plane during the application of negative pressure wound therapy. RESULTS Similar finding were observed at all different negative pressures studied. Negative pressure wound therapy caused the heart to be displaced toward the thoracic wall, and in some cases, the right ventricular free wall bulged into the space between the sternal edges, and the sharp edges of the sternum jutted into and deformed the anterior surface of the right ventricular free wall. These events were not affected by the interposition of 4 layers of paraffin gauze dressing but were hindered by the placement of a rigid barrier between the anterior portion of the heart and the inside of the thoracic wall. CONCLUSION The results show altered position of the heart in relation to the sternum during negative pressure wound therapy. This may explain 2 potentially hazardous events associated with negative pressure wound therapy, namely, risk for heart rupture and reduced cardiac output. Inserting a rigid barrier over the heart may be a protective measure that is clinically practicable.

Off-pump transapical mitral valve replacement: evaluation after one month

OBJECTIVES The present study investigates outcomes one month after implanting pigs with a novel mitral valved stent. METHODS A novel nitinol stent custom designed for this study included a bovine pericardial valve. Six pigs received a valved stent into the mitral position by means of the transapical implantation technique. Afterwards, haemodynamic stability and valve function were assessed, immediately after implantation (n = 6), 4 weeks (n = 4) and 8 weeks (n = 1) thereafter using transoesophageal echocardiography (TEE), ventriculography and cardiac computed tomography (CT). Four of 6 surviving pigs were sacrificed at 4 weeks after implantation and one at 8 weeks thereafter. RESULTS Optimal deployment and positioning were obtained in all but one animal. This animal died of unrecognized imperfect valved stent positioning after 4 days. The average mean gradient across the new valves and the left ventricular outflow tract (LVOT) were small. Mild regurgitation developed after valved stent deployment in one of six animals just after 1 h, and in none thereafter. All animals exhibited normal haemodynamics after mitral valved stent implantation, and stability was maintained throughout the monitoring period. Migration, embolization and paravalvular leakage were not evident in the remaining animals after 4 and 8 weeks. Gross evaluation revealed that 50-70% of the atrial element was covered by tissue growth at 4 weeks/8 weeks. CONCLUSIONS This study demonstrates adequate deployment and anchorage of a unique, repositionable mitral valved stent. A good valve function was revealed in animals observed for 4 weeks and in one pig after 8 weeks.

Elevated growth differentiation factor 15 levels predict outcome in patients undergoing transcatheter aortic valve implantation

Transcatheter aortic valve implantation (TAVI) has emerged as a treatment of aortic stenosis in patients at high surgical risk. However, risk stratification in this elderly population is challenging, as patients at extreme risk might not benefit from TAVI. While several clinical criteria have been proposed for estimating the outcome, prediction of individual risk remains difficult. Therefore, our aim was to assess the prognostic value of the biomarker growth differentiation factor 15 (GDF15).

Factors influencing results and outcome after transmyocardial laser revascularization

BACKGROUND Transmyocardial laser revascularization (TMR) has been increasingly used during the recent past for patients with diffuse coronary artery disease. Because this operation is associated with significant morbidity and mortality, it is important to select patients for TMR who are likely to benefit from the procedure. METHODS We performed an univariate logistic regression analysis of 20 factors on the benefits and outcomes of 134 patients who underwent isolated TMR at our institution between November 1994 and May 2000. RESULTS Responders and nonresponders differed significantly with regard to the incidence of diabetes mellitus. For diabetic patients the chance of profiting from the TMR operation was only 43% of that of nondiabetic patients (odds ratio = 0.43 [0.20 to 0.92]). Furthermore, patients with a preoperative body mass index of less than 25 had a threefold increase in the probability of death during the first year after TMR as compared to patients whose body mass index was 25 or more (odds ratio = 2.97 [1.05 to 8.40]). The incidence of diabetes was also slightly but not significantly different between 1-year survivors and nonsurvivors. CONCLUSIONS In diabetic patients we recommend caution in selecting therapeutic TMR because outcomes are less satisfactory than in nondiabetics. Furthermore, patients with a body mass index below 25 have a significantly higher risk for death during the first postoperative year. Studies based on larger patient populations should follow.

Prevention of surgical site sternal infections in cardiac surgery: a two-centre prospective randomized controlled study

OBJECTIVES Surgical site infection (SSI) of the sternum is a devastating complication in cardiac surgery. The aim of this prospective randomized controlled two-centre clinical study was to compare the use of a gentamicin-collagen sponge (Genta-Coll® resorb) and of a cyanoacrylate-based microbial skin sealant (InteguSeal®) on the SSI rate of the sternum. METHODS We analysed data from 996 consecutive patients following isolated coronary artery bypass grafting between 2012 and 2014. The patients were randomized into three groups: standard group (S-group), Genta-Coll group (G-group) and InteguSeal group (I-group). The primary study end-point was to analyse the incidence of superficial and deep sternal SSI. The secondary study end-point was to determine independent risk factors for an increased SSI rate. RESULTS Of the 996 patients investigated, 332 patients were in S-group, 336 patients in G-group and 328 patients in I-group. The mean age was 67.7 ± 9.4 years, 18.6% were women and the overall SSI rate was 6.2% with 2.2% deep sternal wound infections. SSI rates were 8.3% (S-group), 5.4% (G-group) and 4.9% (I-group) (P 0.16). Multiple regression analysis demonstrated a preoperative body mass index (BMI) of >30 kg/m2 (P 0.047), re-thoracotomy for postoperative bleeding (P < 0.001) and sternum instability (P < 0.001) as independent predictors for an increased SSI rate. CONCLUSIONS The application of InteguSeal® or Genta-Coll® resorb had no significant influence on the incidence of the sternal SSI rate in 996 consecutive cardiac surgery patients but demonstrated a trend towards a benefit from using these prophylactic approaches. Multiple regression analysis demonstrated a preoperative BMI of >30 kg/m2, re-thoracotomy for bleeding and sternum instability as independent predictors for an increased sternal SSI rate.

Extent of Myocardial Tissue Damage During Transmyocardial Laser Revascularization with the CO2 Heart Laser

OBJECTIVE AND BACKGROUND Transmyocardial laser revascularization (TMR) is the only surgical treatment for patients with severe diffuse coronary artery disease, who are not candidates for bypass grafting or percutaneous angioplasty. However, vaporization of tissue during the creation of channels leads to a certain loss of viable myocardium during every TMR procedure. METHODS We analyzed serum levels of creatine kinase and creatine kinase MB subtype in 163 patients after sole TMR with a CO2 laser (wave length 10.6 microm, 800-watt power). The control group consisted of 35 consecutive CABG patients and 30 consecutive redo-CABG patients. Additionally, in the TMR group we measured echocardiographically the left ventricular ejection fraction before and after TMR. We recorded the total amount of laser energy applied, average and maximum energy per channel, and the number of created channels, in order to calculate the correlation between these parameters and postoperative enzyme levels or changes in the LVEF. RESULTS After TMR, we measured higher creatine kinase levels compared to those in CABG patients (607.8+/-558.4 U/L vs. 285.0+/-292.3 U/L, p < 0.01). The relative proportion of CK-MB of total CK, however, was significantly lower after TMR, compared to that of the control group (4.5+/-3.0% vs. 10.1+/-6.4%, p < 0.01). Patients with a pronounced postoperative increase in CK-MB levels or a higher percentage of CK-MB of total CK also after TMR operations show a decline in left ventricular contractility. In the laser group, the maximum enzyme levels were detected significantly later than in the control group (25.0+/-19.4 h postoperatively vs. 8.7+/-9.1 h, p < 0.01). There was no significant correlation between the technical laser parameters or the number of created channels and the percentage of CK-MB of total CK or changes in left ventricular ejection fraction. CONCLUSIONS CO2 laser TMR does not result in significant injury to the myocardium. Cardiac enzymes play an important role in the detection of perioperative myocardial infarction in TMR patients.

Off-pump coronary artery bypass prevents visceral organ damage

OBJECTIVES Visceral malperfusion after coronary artery bypass grafting (CABG) results in high morbidity and mortality. This study was designed to evaluate the effect of CABG performed by surgical techniques on visceral perfusion and function. METHODS Pigs (n = 28) were studied in four groups: I. Sham; II. Off-pump coronary artery bypass grafting (OPCAB): 1 h stabilizer with 40 min intracoronary shunt; III. Extracorporeal circulation (ECC): 1 h ECC with 40 min aortic cross-clamping and cardioplegic arrest; IV. Impella: 1 h left ventricular blood-pump support and stabilizer with 40 min intracoronary shunt. A left internal mammary to left anterior descending coronary artery bypass was performed in Groups II-IV. All animals were observed for a further 240 min. During the experiment haemodynamics, creatinine clearance, intestinal fatty acid binding protein (iFABP), pancreatic (lipase and amylase) and liver enzymes (α-glutathione s-transferase, glutamate-oxaloacetate transaminase (GOT), gamma-glutamyl transferase (GGT), glutamate dehydrogenase and glutamate-pyruvate transaminase (GPT)) were measured. Visceral perfusion (VP) was assessed in both kidneys, intestine, pancreas, liver and spleen with 15 µm fluorescent microspheres. RESULTS During OPCAB surgery, VP decreased slightly. Renal functional parameters, iFABP, pancreatic and liver enzymes remained unchanged. ECC and Impella led to significantly reduced renal, pancreatic and intestinal blood flow (P < 0.05). Creatinine clearance, pancreatic and liver (GPT, GGT) enzymes were significantly decreased only after ECC (P < 0.05). ECC and Impella resulted in a significantly increased iFABP level (P < 0.05). GOT was elevated significantly after surgery in Groups II, III and IV (P < 0.05). CONCLUSIONS CABG with ECC or Impella leads to impaired visceral blood flow and function. OPCAB minimizes these procedure associated alterations.

Short- and long-term follow-up after minimally invasive direct coronary artery bypass in octogenarians

OBJECTIVES Demographic changes lead to a rising incidence of octogenarians undergoing surgical revascularization of coronary artery disease. Minimally invasive direct coronary artery bypass (MIDCAB) represents a surgical treatment with reduced trauma and without the use of cardiopulmonary bypass. The aim of this study was to evaluate short- and long-term outcomes after MIDCAB in octogenarians. METHODS Between 1998 and 2012, 1060 patients underwent MIDCAB at our department. Among them, 72 patients (6.8%) were older than 80 years at the time of operation. Incidence of major adverse cardiac and cerebrovascular events (MACCEs) was compared between octogenarians [median age 82 (81; 85) years, 63.9% male] and younger MIDCAB patients [median age 64 (56; 70) years, 70.7% male] after 30 days and during follow-up. The impact of demographics and preoperative comorbidities on mortality during follow-up was analysed. RESULTS At baseline, the elderly group presented with a statistically significant higher logistic EuroSCORE I (9.2 vs 2.2%, P < 0.001). Within 30 days, octogenarians showed a mortality rate of 5.6% (younger patients 0.8%, P = 0.006) and an MACCE rate of 5.6% (younger patients 1.3%, P = 0.024). The median follow-up time of 30-day survivors was 5.5 (2.9; 7.6) years and follow-up completeness reached 96.9%. In the elderly group, 1-, 3- and 5-year survival rates were 89, 78 and 63% in comparison with 97, 94 and 90% in the younger group (P < 0.001), respectively. The estimated median survival time in octogenarians was 6.7 (CI 4.854; 8.629) years. Logistic regression showed preoperative renal impairment, peripheral arterial occlusive disease and pulmonary hypertension to have a stronger impact on mortality during follow-up than age above 80 years. CONCLUSIONS MIDCAB represents a safe treatment option in octogenarians and is associated with a good perioperative outcome and satisfying long-term results in octogenarians.

Impact of patient-prosthesis mismatch following aortic valve replacement on short-term survival: a retrospective single center analysis of 632 consecutive patients with isolated stented biological aortic valve replacement.

OBJECTIVES The impact of patient-prosthesis mismatch (PPM) after aortic valve replacement (AVR) on short-term and long-term mortality remains controversial. The objective of this study was to evaluate the incidence and severity of PPM and its impact on short-term survival in a large cohort of patients treated with isolated stented biological AVR in a single institution. METHODS We analyzed retrospectively data of 632 consecutive patients with aortic stenosis undergoing isolated stented biological AVR between January 2007 and February 2012 at our institution. PPM was defined as an indexed effective orifice area ≤ 0.85 cm(2)/m(2). Statistical analyses were performed to identify influencing variables on valve size implanted. RESULTS Of the 632 patients investigated, 46% were females and mean age was 71.9 ± 10.4 years. PPM was observed in 93.8% (593 of 632 patients). In 71% of the patients, moderate (0.65-0.85 cm(2)/m(2)) PPM was present and in 22.8% severe (< 0.65 cm(2)/m(2)) PPM was present. The 30-day mortality was 1.4% (9 of 632 patients) with all being females. PPM was not associated with increased 30-day mortality. Multiple regression analyses demonstrated the usefulness of sex, height, body mass index, and body surface area as simultaneous predictors of the valve size implanted (R(2)= 0.39). CONCLUSION PPM had no discernable impact on short-term survival, although it was present in 93.8% of our patients following isolated stented biological AVR.