Is visceral flow during intra-aortic balloon pumping size or volume dependent?

AIM: We evaluated the influence of intra-aortic balloon size and volume on mesenteric and renal flows. METHODS: Thirty healthy swine underwent 120-minute ligation of the left anterior descending coronary artery followed by 6 hours of reperfusion. Then, they were randomly assigned to the following five groups of animals, with six animals in each group: no intra-aortic balloon pump (IABP), a short 35-mL IABP, a short 40-mL IABP, a long 35-mL IABP and a long 40-mL IABP. Superior mesenteric artery (SMA) and renal flows were measured at baseline (t0), at 2-hour ischemia (t1) and every hour thereafter until 6 hours of reperfusion (from tR1 to tR6). RESULTS: SMA flows increased significantly at tR1 only in the two short IABP groups (p<0.001) and balloon volume did not appear to affect flows which, at any experimental time-point, were comparable using 35 mL or 40 mL balloons (p>0.05). Renal flows appeared to be influenced by balloon length, but not by volume. Indeed, flows in the renal arteries rose during IABP treatment; the increase was significantly higher in the short balloon groups and throughout the whole reperfusion (all, p<0.001). CONCLUSIONS: Changes in visceral perfusion during IABP assistance were significantly related to balloon length, but not to its volume. This could be relevant for the evolution of balloon engineering design in order to reduce the incidence of mesenteric ischemia following IABP. Further research is necessary to confirm these findings.

Surgical ablation in patients undergoing mitral valve surgery: impact of lesion set and surgical techniques on long-term success.

AIMS: To assess the results and impact of lesion set and surgical technique on long-term success of surgical ablation during mitral surgery. METHODS AND RESULTS: The patient population consisted of 685 subjects with persistent and long-standing persistent atrial fibrillation (AF) undergoing cardiac surgery for mitral valve disease as the primary indication and concomitant ablation between January 2003 and January 2012 at three institutions. One hundred and sixty-six underwent unipolar (24.2%), 371 (54.2%) bipolar, and 148 (21.6%) had combined ablation. Median follow-up was 58.4 months (interquartile range 43.3-67.9). To appropriately account for death, a competing risk model was employed to identify predictors of cumulative incidence of recurrent AF among lesion set and surgical techniques. Eight-year freedom from recurrent arrhythmia without antiarrhythmic drugs was 0.60 ± 0.02. Success rate was higher using bipolar radiofrequency (RF) (P < 0.001), after performing mitral isthmus line (P = 0.003) and following the biatrial technique (P < 0.001). Competing risk regression revealed that use of unipolar RF [sub-hazard ratio (SHR) 2.41 (1.52-3.43), P < 0.001], combined unipolar/bipolar ablation [SHR 1.93 (0.89-2.57), P = 0.003] and the absence of right atrial ablation [SHR 2.79 (1.27-3.48), P < 0.001] were predictors of cumulative incidence of long-term recurrence. CONCLUSIONS: Our experience suggests that the use of bipolar clamp improves long-term results in surgical treatment of AF and that right-sided ablation should be routinely added. Randomized studies are necessary to confirm our findings.

Uniportal versus multiportal video-assisted thoracoscopic surgery for spontaneous pneumothorax.

BACKGROUND: Multiportal video-assisted thoracic surgery (mVATS) is the standard approach for the surgical treatment of spontaneous pneumothorax. However, uniportal VATS (uVATS) has emerged as an alternative aiming to minimize surgical morbidity. This study aims to strengthen the evidence on the safety and efficiency of uVATS compared to mVATS. METHODS: From January 2004 to December 2020, records of patients who had undergone surgical treatment for primary or secondary spontaneous pneumothorax were evaluated for eligibility. Patients who had undergone pleurectomy combined with bullectomy or apical wedge resection via uVATS or mVATS were included. Surgical characteristics and postoperative data were compared between patients who had undergone surgery via uVATS or mVATS. Univariable and multivariable analyses were performed to determine whether the surgical approach was associated with any complication (primary outcome), major complications (i.e., Clavien-Dindo ≥ 3), recurrence, prolonged hospitalization or prolonged chest drainage duration (secondary outcomes). RESULTS: A total of 212 patients were enrolled. Patients treated via uVATS (n = 71) and mVATS (n = 141) were significantly different in pneumothorax type (secondary spontaneous; uVATS: 54 [76%], mVATS: 79 [56%]; p = 0.004). No significant differences were observed in (major) complications and recurrence rates between both groups. Multivariable analyses revealed that the surgical approach was no significant predictor for the primary or secondary outcomes. CONCLUSIONS: This study indicates that uVATS is non-inferior to mVATS in the surgical treatment of spontaneous pneumothorax regarding safety and efficiency, and thus the uVATS approach has the potential for further improvements in the perioperative surgical care for spontaneous pneumothorax.

Surgical mediastinal lymph node staging for non-small-cell lung carcinoma.

BACKGROUND: The current preferred approach for surgical mediastinal staging of non-small-cell lung carcinoma is video-assisted mediastinoscopy. An alternative technique in which lymph nodes are resected instead of biopsied is video-assisted mediastinoscopic lymphadenectomy (VAMLA) that is suggested to be superior in detecting N2 disease. Yet, evidence is conflicting and furthermore limited by sample size. The objective was to compare mediastinal staging through VAMLA and video-assisted mediastinoscopy. METHODS: A single-center cohort study was conducted. All consecutive patients that underwent surgical mediastinal staging of non-small-cell lung carcinoma by VAMLA (2011 to 2018) were compared to historic video-assisted mediastinoscopy controls (2007 to 2011). Patients with negative surgical mediastinal staging underwent subsequent anatomical resection with systematic regional lymphadenectomy. Primary outcome was the sensitivity and negative predictive value for detecting N2 disease. RESULTS: Two-hundred-sixty-nine video-assisted mediastinoscopic lymphadenectomies and 118 video-assisted mediastinoscopies were performed. The prevalence of N2 disease was 20% and 26% respectively in the VAMLA and video-assisted mediastinoscopy group, while the rate of unforeseen pN2 resulting from lymph node dissection during anatomical resection was 4% and 11%, respectively. Invasive staging using VAMLA demonstrated superior sensitivity of 0.82 and a negative predictive value of 0.96 when compared to video-assisted mediastinoscopy (0.62 and 0.89, respectively), offering a 64% decrease in risk of unforeseen pN2 following anatomical resection. However, VAMLA is also associated with a 75% risk increase on complications (P=0.36). CONCLUSIONS: We conclude that performing invasive mediastinal lymph node assessment for staging of non-small-cell lung carcinoma, VAMLA should be the preferred technique with superior sensitivity and negative predictive value in detecting N2 disease. Though, VAMLA is also associated with an increased risk of complications.

The learning curve of video-assisted mediastinoscopic lymphadenectomy for staging of non-small-cell lung carcinoma.

OBJECTIVES: The objective of this study was to define the learning process of video-assisted mediastinoscopic lymphadenectomy (VAMLA) by the assessment of consecutive procedural metrics. METHODS: We conducted a single-centre retrospective observational study of all consecutive VAMLAs performed between 2011 and 2018 for the staging of non-small-cell lung carcinoma. Learning curves were assessed using non-risk adjusted cumulative observed minus expected (CUSUM) failure charts of complications. Boundary lines were defined by the acceptable and unacceptable complication rates of 4.5% and 15.0%. The Kruskal-Wallis test with post hoc analysis was used to assess trends in operation time and blood loss. RESULTS: Two-hundred-thirty-six unique VAMLAs by 4 surgeons performing their first procedures were evaluated. CUSUM charts of surgeons A and B showed a typical learning curve with an initial incline, followed by a turning point towards lower complications rates after 16-17 cases, whereas surgeons C and D showed an average performance. The median time between consecutive VAMLAs was shorter for surgeons A and B (13.0 vs 28.5-38.0 days for surgeons C and D). Overcoming the learning curve, complication rates of surgeons A and B decreased from 19% to 3% and from 18% to 5%, respectively. Operation time and blood loss showed a significant improvement after, respectively, 81-100 and 61-80 procedures compared to the first 20 procedures. CONCLUSIONS: VAMLA is a safe procedure to adopt and perform with acceptable complication rates from the first operation onward, regardless of the caseload. To overcome its learning curve, 16-17 cases are required, preferably at least 1 per 2 weeks.

Optical imaging versus CT and plain radiography to quantify pectus severity: a systematic review and meta-analysis.

BACKGROUND: Computed tomography (CT) and two-view chest radiographies are the most commonly used imaging techniques to quantify the severity of pectus excavatum (PE) and pectus carinatum (PC). Both modalities expose patients to ionizing radiation that should ideally be avoided, especially in pediatric patients. In an effort to diminish this exposure, three-dimensional (3D) optical surface imaging has recently been proposed as an alternative method. To assess its clinical value as a tool to determine pectus severity we conducted a systematic review in which we assessed all studies that compared 3D scan-based pectus severity measurements with those derived from CT-scans and radiographies. METHODS: Six scientific databases and three registries were searched through April 30th, 2019. Data regarding the correlation between severity measures was extracted and submitted to meta-analysis using the random-effects model and I2-test for heterogeneity. RESULTS: Five observational studies were included, enrolling 75 participants in total. Pooled analysis of participants with PE demonstrated a high positive correlation coefficient of 0.89 [95% confidence interval (CI): 0.81 to 0.93; P<0.001] between the CT-derived Haller index (HI) and its 3D scan equivalent based on external measures. No heterogeneity was detected (I2=0.00%; P=0.834). CONCLUSIONS: 3D optical surface scanning is an attractive and promising imaging technique to determine the severity of PE without exposure to ionizing radiation. However, further research is needed to determine novel cut-off values for 3D scans to facilitate clinical decision making and help determine surgical candidacy. No evidence was found that supports nor discards the use of 3D scans to determine PC severity.

Chest tube drainage versus video-assisted thoracoscopic surgery for a first episode of primary spontaneous pneumothorax: a systematic review and meta-analysis.

Primary spontaneous pneumothorax affects up to 28 patients per 100 000 population yearly and is commonly resolved by chest tube drainage. However, drainage is also known to be associated with ipsilateral recurrence rates ranging from 25% to 43%. Preventive video-assisted thoracoscopic surgery (VATS) may be an effective alternative to diminish these recurrence rates and its associated morbidity. The aim of this study was to compare the efficacy of chest tube drainage and VATS as first line treatments of an initial episode of primary spontaneous pneumothorax. The MEDLINE, EMBASE, CENTRAL and Clinicaltrials.gov databases were searched through 16 September 2018. Data regarding the ipsilateral recurrence rate and the length of hospitalization were extracted and submitted to meta-analysis using the random-effects model and the I2 test for heterogeneity. Two randomized controlled trials and 2 observational studies were included, enrolling a total of 479 patients. Pairwise analysis demonstrated significantly reduced ipsilateral recurrence rates [odds ratio 0.15, 95% confidence interval (CI) 0.07-0.33; P < 0.00001] and length of hospitalization (standardized mean difference -2.19, 95% CI -4.34 to -0.04; P = 0.046) in favour of VATS. However, a significant level of heterogeneity was detected for the length of hospitalization (I2 = 97%; P < 0.00001). Subgroup analysis that stratified study design found no statistical differences regarding recurrence rate. In conclusion, VATS can be an effective and attractive alternative to standard chest tube drainage, with reduced ipsilateral recurrence rates and length of hospitalization. However, given the low quality of the majority of included studies, more well-designed randomized controlled trials are necessary to strengthen the current evidence.

Comparing short versus standard-length balloon for intra-aortic counterpulsation: results from a porcine model of myocardial ischaemia-reperfusion.

OBJECTIVES: We compare a short and a standard-size balloon with same filling volumes to verify the differences in terms of visceral flow, coronary circulation and haemodynamic performance during aortic counterpulsation in an animal model of myocardial ischaemia-reperfusion injury. METHODS: Eighteen healthy pigs underwent 120-min ligation of the left anterior descending coronary artery followed by 6 h of reperfusion, and they were randomly assigned to have intra-aortic balloon counterpulsation (IABP) with a 40-ml short-balloon (n = 6) or a 40-ml standard-length balloon (n = 6), or to undergo no IABP implantation (controls, n = 6). Haemodynamics and visceral and coronary flows were measured at baseline (t0), at 2 h of ischaemia (t1) and every hour thereafter until 6 h of reperfusion (from tR1 to tR6), respectively. RESULTS: Mesenteric flows increased significantly at tR1 only in the short-balloon group (P < 0.001) and it was constantly higher than in the standard-balloon group regardless of mean arterial pressure, systemic vascular resistance and cardiac output (CO; all, P < 0.001). Renal blood flows were significantly increased during IABP treatment with values constantly and significantly higher in short balloons at any following experimental step (all, P < 0.05). IABP improved CO and coronary blood flow, and reduced afterload, myocardial resistances and myocardial oxygen consumption without differences between the short and the standard-length balloon (all, P > 0.05). CONCLUSIONS: The short balloon prevents visceral ischaemia and, compared with the standard-size balloon, it does not lose IABP beneficial cardiac and coronary-related effects. Further studies are warranted to confirm our findings.

The Optimal Weaning Strategy for Intraaortic Balloon Counterpulsation: Volume-Based Versus Rate-Based Approach in an Animal Model.

BACKGROUND: Changes in hemodynamics, coronary circulation, visceral flow, and biochemical marker rate reduction or volume deflation for intraaortic balloon pump discontinuation were assessed. METHODS: Twelve healthy pigs were randomly assigned to two groups, the rate-based (RB, n = 6) and volume-based weaning groups (VB, n = 6). Hemodynamics and visceral and coronary flows were measured at baseline after 2 hours of intraaortic balloon pump 1:1, during the first 5 hours of weaning (frequency rate reduced to 1:2 in the RB group and volume decreased by 10%/h in the VB group), after 1 hour of frequency rate 1:3 in the RB group or a volume decrease by 75% in the VB group, 2 hours after withdrawal, and 4 hours after withdrawal. RESULTS: The animals weaned by progressive VB deflation showed a greater degree of vasodilation, better cardiac output and stroke volume, fewer negative values of cardiac cycle efficiency, and higher dP/dTmax compared with those weaned by RB reduction (p < 0.05 for all). The VB group also exhibited increased coronary flow, lower oxygen consumption of the myocardium, and coronary resistance during VB weaning (p < 0.05 for all). The serum lactate level was lower in the VB group at each experimental point (p < 0.05 for all), but visceral flows were scarcely affected by the weaning method. CONCLUSIONS: Volume reduction was the most effective weaning method considering that frequency reduction weaning was responsible for significant negative effects on hemodynamics and coronary circulation.

The ABLA-BOX: An In Vitro Module of Hybrid Atrial Fibrillation Ablation.

OBJECTIVE: We present the first testing study on the ABLA-BOX, a new in vitro module of hybrid atrial fibrillation ablation. METHODS: ABLA-BOX consists of two chambers that mimic the epicardial and endocardial sides of the heart. The septum between chambers provides catheter access on both sites of the cardiac tissue. A circuit, filled with freshly obtained porcine blood, including a pump, an oxygenator, and a heating device, circulate the blood inside the system. Left atrial fresh tissue is mounted on a tissue holder and magnetically fixed. Epicardial and endocardial catheters are fixed on the catheter holders and blocked with the locker knob. The system allows control of ablation force, flow rate, temperature, and flow pattern. RESULTS: Epicardial contact force of 100 g and endocardial force of 30 g resulted in larger lesion volumes (P < 0.001), areas (P < 0.001), and lesion diameters (P = 0.03 and P = 0.008), than the combination of 100/20 g. In addition, with a flow rate of 5 L/min, lesion volumes (P = 0.02), areas (P < 0.001), and diameters (both, P < 0.001) were significantly larger in comparison with those of 3 L/min. Furthermore, dimensions (both, P < 0.001), volume (P < 0.001), and area (P < 0.001) of the lesions at a circulating blood temperature of 38.0°C were larger than with a lower blood temperature (36.0°C). Finally, ablations made under stable flow pattern resulted in greater lesion diameters (P = 0.04 and P = 0.03) as well as larger volumes (P = 0.02) and areas (P = 0.03) than under turbulent-like flow reproduced with the system rotor set to 400 rpm. CONCLUSIONS: The ABLA-BOX allowed easy hybrid ablation with different setups, which can provide cardiologists and cardiac surgeons with reliable and more valuable insights.

Short intra-aortic balloon pump in a swine model of myocardial ischaemia: a proof-of-concept study.

OBJECTIVES: This proof-of-concept study examined the haemodynamic performance as well as the coronary and visceral organ perfusion using a new short balloon for intra-aortic counterpulsation (IABP) in a swine model of myocardial ischaemia. METHODS: Eighteen healthy pigs underwent 120-min ligation of the left anterior descending coronary artery followed by 6 h of reperfusion, and they were randomly assigned into 3 groups undergoing IABP implantation with a 35-ml short balloon (n = 6), a 40-ml short balloon (n = 6) or no IABP implantation (controls, n = 6). Haemodynamics, and visceral and coronary flows were measured at baseline (t0), at 2 h of ischaemia (t1) and every hour thereafter until 6 h of reperfusion (from tR1 to tR6), respectively. RESULTS: Mesenteric and renal flows increased significantly at tR1 only in the IABP groups (all, P < 0.001) and were significantly higher than controls throughout the reperfusion periods (P < 0.001). Coronary systolic and diastolic blood flows increased only at tR1 in the IABP groups (all, P < 0.001) but were higher than controls at tR1-tR6. The IABP was associated with enhanced haemodynamics compared with controls. No difference was detected using different balloon volumes (all, P > 0.05). CONCLUSIONS: The new short balloon significantly increased visceral flow, enhanced haemodynamics and improved coronary circulation during reperfusion following myocardial ischaemia in our experimental model.

Contact forces during hybrid atrial fibrillation ablation: an in vitro evaluation.

PURPOSE: Data on epicardial contact force efficacy in dual epicardial-endocardial atrial fibrillation ablation procedures are lacking. We present an in vitro study on the importance of epicardial and endocardial contact forces during this procedure. METHODS: The in vitro setup consists of two separate chambers, mimicking the endocardial and epicardial sides of the heart. A circuit, including a pump and a heat exchanger, circulates porcine blood through the endocardial chamber. A septum, with a cut out, allows the placement of a magnetically fixed tissue holder, securing porcine atrial tissue, in the middle of both chambers. Two trocars provide access to the epicardium and endocardium. Force transducers mounted on both catheter holders allow real-time contact force monitoring, while a railing system allows controlled contact force adjustment. We histologically assessed different combinations of epi-endocardial radiofrequency ablation contact forces using porcine atria, evaluating the ablation's diameters, area, and volume. RESULTS: An epicardial ablation with forces of 100 or 300 g, followed by an endocardial ablation with a force of 20 g did not achieve transmurality. Increasing endocardial forces to 30 and 40 g combined with an epicardial force ranging from 100 to 300 and 500 g led to transmurality with significant increases in lesion's diameters, area, and volumes. CONCLUSIONS: Increased endocardial contact forces led to larger ablation lesions regardless of standard epicardial pressure forces. In order to gain transmurality in a model of a combined epicardial-endocardial procedure, a minimal endocardial force of 30 g combined with an epicardial force of 100 g is necessary.

The "Spacemaker", a New Device for Minimally Invasive Cardiothoracic Surgery: An Evaluation and Feasibility Study.

OBJECTIVE: Our aim was to evaluate a new inflatable lung retractor, the "Spacemaker", and its efficacy in facilitating minimally invasive cardiothoracic surgery without the need of one lung ventilation or carbon dioxide overpressure insufflation. METHODS: The device was tested in 12 anesthetized pigs (90-100 kg) placed on standard endotracheal ventilation. The device was introduced into the right or left side of the chest, depending on the intended procedure to be performed, via a 3-cm incision in the fifth intercostal space. A total of seven animals were used to evaluate hemodynamic and respiratory response to the device, whereas another five animals were used to assess the feasibility of a variety of minimally invasive cardiothoracic surgical procedures. RESULTS: Introduction was easy and unhindered. The device was inflated up to 0.6 bar, thereby pushing the lung tissue gently away cranially, posteriorly, and caudally without interfering with pulmonary function or resulting in respiratory compromise. In addition, hemodynamics remained stable throughout the experiments. Different closed-chest surgical procedures such as left atrial appendage exclusion, pulmonary vein exposure, pacemaker lead placement, and endoscopic stabilization for coronary surgery, were successfully performed. Removal was quick and complete in all cases, and lung tissue showed no remnant atelectasis. CONCLUSIONS: The "Spacemaker" may represent a reliable alternative to current conventional techniques to facilitate minimally invasive cardiothoracic surgery. Further research is warranted to confirm the effectiveness and the safety of this device and to optimize the model before its use in humans and its introduction into clinical practice.

Guideline adherence in antithrombotic treatment after concomitant ablation surgery in atrial fibrillation patients.

OBJECTIVES: We investigated real-life oral anticoagulation (OAC) treatment after surgical ablation and examined its adherence to current recommendations. We also explored factors related to OAC use preoperatively and at follow-up. METHODS: One hundred and fifteen patients with atrial fibrillation (AF) were evaluated during 12-month follow-up after surgery. Patients were divided into two categories according to the congestive heart failure, hypertension, age ≥75 years, diabetes and prior stroke [or transient ischaemic attack or thromboembolism] (CHADS2) score: 60 patients were assigned to the high-risk group (CHADS2 score ≥2) and 55 to the low-risk group (CHADS2 score ≤1). OAC use was defined as guideline adherent, undertreatment or overtreatment. RESULTS: Baseline overall guideline adherence was 62%. OAC was underprescribed in high-risk patients and overprescribed in low-risk patients (both, P < 0.001). The only factor associated with OAC use after logistic regression analysis were age >75 years (P = 0.01) and preoperative AF > paroxysmal (P = 0.013). Overall guideline adherence at 12-month follow-up showed a trend towards a better adherence in the sinus rhythm (SR) subgroup (74% vs 55%, P = 0.02). OAC was underprescribed in high-risk patients and overprescribed in low-risk patients (both P < 0.001). After logistic regression analysis, preoperative OAC use (P = 0.007) and other indications for OAC (P = 0.01) were predictors of anticoagulation treatment. CONCLUSIONS: Real-life OAC prescription in AF patients showed a moderate guideline adherence, with high-risk patients being undertreated and low-risk patients being overtreated. These findings stress the importance that antithrombotic treatment in patients undergoing AF surgery needs to be critically re-evaluated.

Poststernotomy mediastinitis and the role of broken steel wires: retrospective study.

OBJECTIVE: Mediastinitis is a severe complication of cardiac surgery. Sternal instability is concomitantly present in most cases. Broken steel wires may cause sternal instability. In this study, the role of broken steel wires in sternal closure was evaluated in patients who developed poststernotomy mediastinitis. METHODS: Preoperative, perioperative, and postoperative data of patients who underwent thoracic surgery between 1996 and 2006 were retrieved from the SUMMIT registry database. Patients needing reoperation for mediastinitis were identified. Patients' charts and chest radiographs from initial surgery to reoperation for mediastinitis were reviewed. RESULTS: Forty-five patients developed postoperative mediastinitis needing reoperation (0.6%). Because of loss to follow-up, 31 patients were evaluated. Eight patients (25.8%) presented fractured steel wires. Most of the broken steel wires (87.5%) manifested at the cranial site of figure-of-eight configurations. In the patients without broken steel wires, mediastinitis manifested after 14 days compared with 38 days in the patients with broken wires. Time until mediastinitis was not significantly different (P = 0.229). The mean time until steel wire disruption was 14 days (range, 4-48 days). CONCLUSIONS: Broken steel wires were observed before mediastinitis became manifest. Fracturing occurred mainly at the cranial site of figure-of-eight configurations. The results of the present study emphasize that closure technique plays a prominent role in the development of mediastinitis. Because mediastinitis is associated with an increased risk for early morbidity, attention should be paid to patients presenting with broken steel wires. New techniques for median sternotomy closure are needed that are less prone to mechanical fatigue than are steel wires.