Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where Johan van der Merwe is active.

Publication


Featured researches published by Johan van der Merwe.


Interactive Cardiovascular and Thoracic Surgery | 2016

Late redo-port access surgery after port access surgery

Johan van der Merwe; Filip Casselman; Bernard Stockman; Yvette Vermeulen; Ivan Degrieck; Frank Van Praet

OBJECTIVES This study presents the first report on short- and long-term outcomes in redo-port access surgery after previous port access surgery (redo-PAS-PAS) for new or recurrent mitral valve (MV) and tricuspid valve (TV) disease. METHODS Our current surgical team performed redo-PAS-PAS in 26 consecutive patients who had previous port access surgery (mean age 65.8 ± 13.3 years, 46.2% female, 42.3% older than 70 years, mean logistical EuroSCORE 22.5 ± 21.6%) between 1 February 1997 and 30 June 2014. Surgical indications included among others MV prosthesis dysfunction (n = 8, 30.8%), endocarditis (n = 10, 38.5%) and TV dysfunction (n = 3, 11.5%). The mean time interval between primary PAS and redo-PAS-PAS was 70.32 ± 57.4 months. RESULTS Redo-PAS-PAS procedures included MV replacement (n = 19, 73.1%), MV repair (n = 5, 19.2%), and TV repair (n = 2, 7.7%). Sternotomy conversion was required in 5 patients (19.2%), of which 4 (15.4%) were early conversions due to lung adhesion and 1 (3.8%) due to a late intraoperative complication. The mean cardiopulmonary bypass and cross-clamp times were 163.3 ± 57.9 and 101.2 ± 43.8 min, respectively. Postoperative mechanical ventilation longer than 72 h was required in 4 patients (15.4%). In-hospital morbidities included hospital-acquired pneumonia (n = 3, 11.5%), postoperative air leaks (n = 2, 7.7%) and revision for bleeding (n = 1, 3.8%). The mean length of hospital stay was 16.1 days. Long-term clinical and echocardiographic follow-up were 48.3 ± 39.2 and 44.6 ± 32.9 months, respectively. The Kaplan-Meier analyses for survival and freedom from mitral and tricuspid valve reintervention (n = 26) at 5 years were 83.9 and 95.8%, respectively, with 91.3% of surviving patients classified as being NYHA II or less. Echocardiographic follow-up showed no residual mitral regurgitation more than grade I in all redo mitral valve repairs and no paravalvular leak post-valve replacement. CONCLUSIONS Redo-PAS-PAS is our routine approach and we apply this strategy in the majority of patients who had previous port access surgery. The predicted procedure-related mortality, morbidities, patient satisfaction and long-term outcomes are favourable.


Annals of cardiothoracic surgery | 2015

Minimally invasive primary aortic valve surgery: the OLV Aalst experience

Johan van der Merwe; Filip Casselman; Bernard Stockman; Frank Van Praet; Roel Beelen; Lieven Maene; Yvette Vermeulen; Ivan Degrieck

BACKGROUND The purpose of this study was to evaluate our in-hospital outcomes with primary J-sternotomy aortic valve surgery since the initiation of our program in 1997. METHODS Between October 1(st) 1997 and August 31(st) 2014, 768 patients (mean age: 69.1±11.2 years, 46.6% females, 15.6% aged greater than 80 years) underwent primary JS-AVS. Additional risk factors included diabetes mellitus (n=98, 12.2%), peripheral vascular disease (n=42, 5.5%) and body mass index greater than 30 (n=144, 18.8%). The mean logistical EuroSCORE I was 5.46%±4.5%. RESULTS Aortic valve replacement and repair were performed in 758 (98.7%) and 10 (1.3%) patients respectively, for isolated valve stenosis (n=472, 61.8%), incompetence (n=56, 7.3%) and mixed valve disease (n=236, 30.9%). Valve pathology included sclerosis (n=516, 67.2%), rheumatic disease (n=110, 14.3%) and endocarditis (n=10, 1.3%). Reasons for conversion to full sternotomy (n=23, 3.0%) included porcelain ascending aorta (n=3, 0.4%), inadequate visualization (n=2, 0.3%) and intra-operative complications (n=18, 2.3%). Mean length of hospital stay was 11.0±7.4 days. Morbidity included stroke (n=15, 2.0%), revision or re-exploration (n=52, 6.8%), atrial fibrillation (n=201, 26.2%) and sternitis (n=5, 0.7%). In-hospital mortality was 1.6% (n=12). Overall survival at 30 days was 98.0%. CONCLUSIONS JS-AVS is safe and is our routine approach for isolated aortic valve disease. Procedure related mortality is lower than predicted, conversion rates limited and significant morbidity minimal.


The Journal of Thoracic and Cardiovascular Surgery | 2016

The present day potential role of fractional flow reserve–guided coronary artery bypass graft surgery

Filip Casselman; Johan van der Merwe; Angela Ferrara; Emanuele Barbato

The favorable impact of fractional flow reserve measurements on the decision-making and overall outcomes of percutaneous coronary artery intervention is well established. However, the clinical application of fractional flow reserve in surgical revascularizations is still debated. The purpose of this article is to provide a comprehensive review on the current potential role of fractional flow reserve guidance in coronary artery bypass grafting.


The Annals of Thoracic Surgery | 2015

Single-Stage Minimally Invasive Surgery for Synchronous Primary Pulmonary Adenocarcinoma and Left Atrial Myxoma

Johan van der Merwe; Roel Beelen; Sebastiaan Martens; Frank Van Praet

We report the first successful short-term outcome of single-stage combined video-assisted thoracoscopic surgery lobectomy and port access surgery in a patient with operable primary right lower lobe adenocarcinoma and a synchronous cardiac myxoma. The video-assisted thoracic surgery right lower lobectomy with systematic lymph node dissection was performed first, followed by myxoma excision by port access surgery through the same working port incision. The histopathologic analysis confirmed a pT2a N0 M0 R0 (TNM 7th edition) primary poorly differentiated pulmonary adenocarcinoma and a completely excised cardiac myxoma. Postoperative recovery was uneventful, and follow-up at 6 weeks confirmed an excellent surgical and oncologic outcome.


Journal of Visceral Surgery | 2018

Endoscopic Port Access TM left ventricle outflow tract resection and atrioventricular valve surgery

Johan van der Merwe; Filip Casselman; Frank Van Praet

The continuous evolution in robotic-, endoscopic- and trans-catheter cardiac interventions resulted in innovative techniques that simultaneously address left ventricular outflow tract obstruction (LVOTO) and concomitant atrioventricular valve (AVV) pathology in the context of hypertrophic obstructive cardiomyopathy (HOCM). We present our brief report of 13 consecutive HOCM patients with concomitant AVV disease, who underwent endoscopic left ventricular septal myomectomy (LVSM) and AVV surgery by Endoscopic Port AccessTM Surgery (EPAS) between March 1st 2010 and October 31st 2015. Our EPAS technique in the context of HOCM utilizes peripheral cardiopulmonary bypass, endo-aortic balloon occlusion and a 4-cm right antero-lateral thoracic working port. Access to the LVOTO is obtained by detaching the anterior mitral valve (MV) leaflet from the annulus. Controlled sharp LVSM is then performed from the aortic leaflet base to the papillary muscles. Subsequent routine AVV surgery is performed using long shafted instruments. There were no sternotomy conversions, LVSM complications or 30-day mortalities. The mean length of hospitalization was 17.7±18.1 days. Long-term clinical and echocardiographic analysis of 645.7 patient-months (n=13, 100.0% complete) identified two late mortalities, which were not procedure-, HOCM- or AVV-related. All patients (n=13, 100.0%), including the late mortalities, had significant improvement in their quality of life, a 100% long-term freedom from re-intervention and no residual peak instantaneous LVOTO gradients more than 15 mmHg. This brief report emphasises that simultaneous LVSM and concomitant AVV surgery by EPAS can safely be performed in experienced centres with favourable long-term outcomes.


Interactive Cardiovascular and Thoracic Surgery | 2018

Endoscopic port access surgery for isolated atrioventricular valve endocarditis

Johan van der Merwe; Filip Casselman; Bernard Stockman; Apostolos Roubelakis; Yvette Vermeulen; Ivan Degrieck; Frank Van Praet

OBJECTIVES Our goal was to report the clinical and echocardiographic outcomes of endoscopic port access surgery for isolated active and convalescent atrioventricular valve endocarditis (AVVE). METHODS Our current surgical team performed endoscopic port access surgery in 66 consecutive patients with isolated AVVE (mean age, 65.5 ± 12.7 years, 37.9% women, mean EuroSCORE II 31.2 ± 24.9%, 45.5% prosthetic AVVE, Staphylococcus aureus 22.2%), between 1 May 2004 and 31 July 2015. Isolated mitral valve endocarditis was present in 53 (80.4%) patients, including 11 (16.7%) with periannular abscesses. RESULTS Procedures performed included mitral valve repair (n = 15, 22.7%) and left ventricular septal myomectomy (n = 1, 1.5%). Reasons for sternotomy conversion (n = 6, 9.1%) included lung adhesions (n = 3, 4.5%). The mean cardiopulmonary bypass and ischaemic times were 167.2 ±48.7 and 112.6 ± 33.3 min, respectively. In-hospital morbidities included revision for bleeding (n = 6, 9.1%). The 30-day survival rate was 87.9%. Causes of in-hospital deaths (n = 12) included low cardiac output syndrome (n = 3, 4.5%). Age, critical preoperative status and EuroSCORE II score predicted deaths individually at the 5% level of significance. The Kaplan-Meier analyses (mean 63.2 ± 42.5 months) for survival and freedom from AVVE reintervention at 10 years were 69.4% and 98.4%, respectively. Of the mid-term survivors (n = 50, 93.9% complete), 94.0% (n = 47) classified as New York Heart Association (NYHA) II or less with no mitral valve regurgitation greater than Grade I. CONCLUSIONS Complex atrioventricular valve surgery in the context of AVVE can be endoscopically performed in experienced centres and should not deter surgeons from offering patients with AVVE the potential benefits of minimally invasive cardiac surgery.


Open Journal of Cardiovascular Surgery | 2017

Mitral Valve Replacement—Current and Future Perspectives

Johan van der Merwe; Filip Casselman


Interactive Cardiovascular and Thoracic Surgery | 2016

Robotic-enhanced coronary surgery in octogenarians

Apostolos Roubelakis; Filip Casselman; Johan van der Merwe; Bernard Stockman; Ivan Degrieck; Frank Van Praet


Interactive Cardiovascular and Thoracic Surgery | 2016

Endoscopic atrioventricular valve surgery in adults with difficult-to-access uncorrected congenital chest wall deformities

Johan van der Merwe; Filip Casselman; Bernard Stockman; Yvette Vermeulen; Ivan Degrieck; Frank Van Praet


European Journal of Cardio-Thoracic Surgery | 2018

Reasons for conversion and adverse intraoperative events in Endoscopic Port Access™ atrioventricular valve surgery and minimally invasive aortic valve surgery

Johan van der Merwe; Frank Van Praet; Bernard Stockman; Ivan Degrieck; Yvette Vermeulen; Filip Casselman

Collaboration


Dive into the Johan van der Merwe's collaboration.

Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar

Emanuele Barbato

University of Naples Federico II

View shared research outputs
Researchain Logo
Decentralizing Knowledge