Marc R. de Leval

Human factors and cardiac surgery: A multicenter study ☆ ☆☆ ★ ★★

OBJECTIVE To study the role of human factors on surgical outcomes, with a series of 243 arterial switch operations performed by 21 surgeons taken as a model. METHODS The following data were collected: patient-specific and procedural variables, self-assessment questionnaires, and a written report from a human factors researcher who observed the operation. The relationship of patient-specific variables to outcomes (death and death and/or near miss) was used to develop a multivariable baseline model to analyze the role of human factors after adjustment for these variables. RESULTS The overall mortality was 6.6% with 24.3% of cases resulting in death and death and/or near misses. The self-assessment questionnaires were found to be unhelpful. Major and minor human failures were extracted from the written report. Major negative events were potentially life-threatening failures, whereas minor events were failures that, in isolation, were not expected to have serious consequences. Major events were closely related to death (P <.001) and death and/or near misses (P <.001). Appropriate compensation, however, sharply reduced the risk of death (P =.003). The total number of minor events was also closely related to both death and death and/or near misses (P <.001). CONCLUSION The study highlights the role of human factors in negative surgical outcomes. Even in the most eventful circumstances, however, appropriate human factors defense mechanisms can lead to a successful outcome.

Patient handover from surgery to intensive care: using Formula 1 pit‐stop and aviation models to improve safety and quality

Background:  We aimed to improve the quality and safety of handover of patients from surgery to intensive care using the analogy of a Formula 1 pit stop and expertise from aviation.

The human factor in cardiac surgery: errors and near misses in a high technology medical domain.

In this review, we discuss human factors research in cardiac surgery and other medical domains. We describe a systems approach to understanding human factors in cardiac surgery and summarize the lessons that have been learned about critical incident and near-miss reporting in other high technology industries that are pertinent to this field.

Behavioural markers of surgical excellence

Abstract This paper applies the concept of behavioural markers of performance, previously used to understand the characteristics of the most successful aviation crews (Connelly, E.P., 1997. A Resource Package for CRM Developers: Behavioural Markers of CRM Skill From Real World Case Studies and Accidents. University of Texas Crew Research Project Technical Report, pp. 97–103; Helmreich, R.L., Merritt, A.C., 1998. Culture at Work in Aviation and Medicine: National, Cultural and Professional Influences. Ashgate Publishers, Aldershot, UK), to a surgical domain. A framework of ‘behavioural markers’ of surgical excellence was developed based on existing research. This framework was used to explain differences in ‘procedural excellence scores’ amongst a group of sixteen UK paediatric cardiac surgeons who had participated in a multi-centre UK study on the influence of human factors on surgical outcomes. Procedural exellence scores were derived from multivariable logistic regression models of the number of major and minor events (i.e. errors) per case, adjusted for known patient risk factors. Two binary outcomes were predicted; death and death and/or near miss. Results showed that those surgeons with the best scores (surgeons 3, 5, 8 and 14) were characterised by more of the behavioural markers than surgeons with lower scores. It is concluded that although behavioural markers have proven a useful method to explain performance differences between surgeons, further research is needed to validate and quantify the markers developed in this study and to test their applicability in other medical domains.

Computational fluid dynamics in the evaluation of hemodynamic performance of cavopulmonary connections after the Norwood procedure for hypoplastic left heart syndrome.

OBJECTIVE Computational fluid dynamics have been used to study the hemodynamic performance of surgical operations, resulting in improved design. Efficient designs with minimal energy losses are especially important for cavopulmonary connections. The purpose of this study was to compare hydraulic performance between the hemi-Fontan and bidirectional Glenn procedures, as well as the various types of completion Fontan operations. METHODS Three-dimensional models were constructed of typical hemi-Fontan and bidirectional Glenn operations according to anatomic data derived from magnetic resonance scans, angiocardiograms, and echocardiograms. Boundary conditions were imposed, and fluid dynamics were calculated from a mathematic code. Power losses, flow distribution to each lung, and pressures were measured at three predetermined levels of pulmonary arteriolar resistance. Models of the lateral tunnel, total cavopulmonary connection, and extracardiac conduit completion Fontan operations were constructed, and power losses, total flow distribution, vena caval and pulmonary arterial pressures, and flow distribution of inferior vena caval return were calculated. RESULTS The hemi-Fontan and bidirectional Glenn procedures performed nearly identically, with similar power losses and nearly equal flow distributions to each lung at all levels of pulmonary arteriolar resistance. However, the lateral tunnel Fontan procedure as performed after the hemi-Fontan operation had lower power losses (6.9 mW, pulmonary arteriolar resistance 3 units) than the total cavopulmonary connection (40.5 mW) or the extracardiac conduit (42.9 mW), although the inclusion of an enlargement patch toward the right in the total cavopulmonary connection was effective in reducing the difference (10.0 mW). Inferior vena caval flow to the right lung was 52% for the lateral tunnel, compared with 19%, 30%, 19%, and 15% for the total cavopulmonary connection, total cavopulmonary connection with right-sided enlargement patch, extracardiac conduit, and extracardiac conduit with a bevel to the left lung, respectively. CONCLUSIONS According to these methods, the hemi-Fontan and bidirectional Glenn procedures performed equally well, but important differences in energy losses and flow distribution were found after the completion Fontan procedures. The superior hydraulic performance of the lateral tunnel Fontan operation after the hemi-Fontan procedure relative to any other method may be due to closer to optimal caval offset achieved in the surgical reconstruction.

Innervation of Human Atrioventricular and Arterial Valves

BACKGROUND Limited information exists on the innervation of human cardiac valves and the relationship of nerve fibers and terminals with functional elements within leaflets. METHODS AND RESULTS We examined human AV and arterial valves, obtained postmortem and at surgery, using quantitative immunohistochemical, histochemical, and confocal microscopic techniques. Significant differences in nerve density and distribution were found both between and within cardiac valves. Nerve density within the anterior leaflet of the mitral valve, for example, was twofold greater than that in the posterior leaflet (P < .001). Nerves within the AV valves were situated in the atrial layer and extended over the proximal and medial portions of the leaflets, whereas those in the arterial valves were situated in the ventricular layer. No nerves reached either the free edge or the fibrous core of the leaflets. The arterial valves displayed a similar density of innervation, except for the noncoronary leaflet of the aortic valve in which the innervation was attenuated (P < .01). The innervation of aortic valvar leaflets was age dependent. Nerve terminal arborizations, arising from myelinated nerves and exhibiting variable morphology, were detected in all four cardiac valves and in some tendinous cords. Nerve terminals exhibited either acetylcholinesterase activity or tyrosine hydroxylase and neuropeptide Y immunoreactivity. Varicose nerve fibers occurred in close physical proximity to valvar endothelial, smooth muscle, and fibroblast cells. CONCLUSIONS Human cardiac valves have distinct patterns of innervation that comprise both primary sensory and autonomic components. The presence of distinct nerve terminals and the close association of varicose nerve fibers with endothelial, smooth muscle, and fibroblast cells suggest a possible neural involvement in the control of valvar function.

Four decades of Fontan palliation

The Fontan palliation was introduced in 1968 to treat cardiac malformations unsuitable for biventricular repair. This procedure has transformed the surgical management of congenital heart disease. In this Review, we reflect on the outcomes and clinical problems associated with this unique circulation after more than 40 years of experience. We also summarize the evolution of the Fontan procedure, highlight the long-term clinical issues and their management, and consider future expectations of a circulation driven by a single ventricle with the systemic and pulmonary blood flow in series rather than in parallel.

The Fontan circulation: a challenge to William Harvey?

In children born with only one ventricle, the systemic and pulmonary venous blood mixes. The Fontan operation, by which the blood flows through the creation of a serial arrangement in which no ventricle interposes, has become the procedure of choice. The development of this therapy and the current issues associated with it are discussed here.AbstractThe Fontan operation, which places the systemic and pulmonary circulations in series and is driven by a single ventricular chamber, is the treatment of choice for patients born with one ventricle. Its introduction 35 years ago was the result of a flurry of experimental and clinical research that had started in the 1940s. A large number of children have benefited and continue to benefit from the Fontan operation, but there is a genuine concern that, despite the refinement of the surgical procedures in the past 20 years, continuing attrition might be inevitable. This adverse effect can lead to a decline in functional capacity, and premature late death.The Fontan operation, which places the systemic and pulmonary circulations in series and is driven by a single ventricular chamber, is the treatment of choice for patients born with one ventricle. Its introduction 35 years ago was the result of a flurry of experimental and clinical research that had started in the 1940s. A large number of children have benefited and continue to benefit from the Fontan operation, but there is a genuine concern that, despite the refinement of the surgical procedures in the past 20 years, continuing attrition might be inevitable. This adverse effect can lead to a decline in functional capacity, and premature late death.

Is a high-risk biventricular repair always preferable to conversion to a single ventricle repair?

OBJECTIVES The aim of this report is to examine the short-and intermediate-term outcome of a complex biventricular repair compared with a single ventricle repair in patients with two functional ventricles. PATIENT POPULATION Since 1986, 34 patients with atrioventricular concordance or discordance, ventriculoarterial discordance, ventricular septal defect, and pulmonary stenosis or atresia have undergone biventricular repair (group I). Another group of 16 patients (group II) with the same diagnoses have undergone a single ventricle repair consisting of a total cavopulmonary connection because of either a straddling atrioventricular valve (11 patients) or an uncommitted ventricular septal defect (5 patients). RESULTS The mean length of follow-up was 3.9 years in group I and 3.0 years in group II. Freedom from reoperation at 7 years was 45.5% in group I and 100% in group II (p = 0.014). The actuarial estimate of survival at 7 years was 68.0% in group I and 93.8% in group II (p = 0.048). CONCLUSION Short- and intermediate-term morbidity and mortality were greater in patients undergoing a biventricular repair than in a similar group of patients undergoing total cavopulmonary connection. It is unknown whether the long-term results of a total cavopulmonary connection in patients with two ventricles are as good as those obtained with a biventricular approach. However, there may be situations in which the short- and intermediate-term risks of a complex biventricular repair may outweigh the long-term disadvantages of a single ventricle approach.

Computational Fluid Dynamics Simulations in Realistic 3-D Geometries of the Total Cavopulmonary Anastomosis: The Influence of the Inferior Caval Anastomosis

Fluid dynamics of Total Cavo-Pulmonary Connection (TCPC) were studied in 3-D models based on real dimensions obtained by Magnetic Resonance (MR) images. Models differ in terms of shape (intra- or extra-cardiac conduit) and cross section (with or without patch enlargement) of the inferior caval (IVC) anastomosis connection. Realistic pulsatile flows were submitted to both the venae cavae, while porous portions were added at the end of the pulmonary arteries to reproduce the pulmonary afterload. The dissipated power and the flow distribution into the lungs were calculated at different values of pulmonary arteriolar resistances (PAR). The most important results are: i) power dissipation in different TCPC designs is influenced by the actual cross sectional area of the IVC anastomosis and ii) the inclusion of a patch minimizes the dissipated power (range 4-13 mW vs. 14-56 mW). Results also show that the perfusion of the right lung is between 15% and 30% of the whole IVC blood flow when the PAR are evenly distributed between the right and the left lung.