Cardiac surgeons' concerns, perceptions, and responses during the COVID-19 pandemic

Background

The coronavirus disease 2019 (COVID‐19) pandemic has had an unprecedented impact on health care and cardiac surgery. We report cardiac surgeons' concerns, perceptions, and responses during the COVID‐19 pandemic.

Methods

A detailed survey was sent to recruit participating adult cardiac surgery centers in North America. Data regarding cardiac surgeons' perceptions and changes in practice were analyzed.

Results

Our study comprises 67 institutions with diverse geographic distribution across North America. Nurses were most likely to be redeployed (88%), followed by advanced care practitioners (69%), trainees (28%), and surgeons (25%). Examining surgeon concerns in regard to COVID‐19, they were most worried with exposing their family to COVID‐19 (81%), followed by contracting COVID‐19 (68%), running out of personal protective equipment (PPE) (28%), and hospital resources (28%). In terms of PPE conservation strategies among users of N95 respirators, nearly half were recycling via decontamination with ultraviolet light (49%), followed by sterilization with heat (13%) and at home or with other modalities (13%). Reuse of N95 respirators for 1 day (22%), 1 week (21%) or 1 month (6%) was reported. There were differences in adoption of methods to conserve N95 respirators based on institutional pandemic phase and COVID‐19 burden, with higher COVID‐19 burden institutions more likely to resort to PPE conservation strategies.

Conclusions

The present study demonstrates the impact of COVID‐19 on North American cardiac surgeons. Our study should stimulate further discussions to identify optimal solutions to improve workforce preparedness for subsequent surges, as well as facilitate the navigation of future healthcare crises.

Long-term Outcomes of Multiple Arterial Coronary Artery Bypass Grafting: A Population-Based Study of Patients in British Columbia, Canada

Importance

Although the long-term survival advantage of multiple arterial grafting (MAG) vs the standard use of left internal thoracic artery (LITA) supplemented by saphenous vein grafts (LITA+SVG) has been demonstrated in several observational studies, to our knowledge its safety and other long-term clinical benefits in a large, population-based cohort are unknown.

Objective

To compare the safety and long-term outcomes of MAG vs LITA+SVG among overall and selected subgroups of patients.

Design, Setting, and Participants

In this population-based observational study, we included 20 076 adult patients with triple-vessel or left-main disease who underwent primary isolated coronary artery bypass grafting (MAG, n = 5580; LITA+SVG, n = 14 496) in the province of British Columbia, Canada, from January 2000 to December 2014, with follow-up to December 2015. We performed propensity-score analyses by weighting and matching and multivariable Cox regression to minimize treatment selection bias.

Exposures

Multiple arterial grafting or LITA+SVG.

Main Outcomes and Measures

Mortality, repeated revascularization, myocardial infarction, heart failure, and stroke.

Results

Of 5580 participants who underwent MAG, 586 (11%) were women and the mean (SD) age was 60 (8.7) years. Of 14 496 participants who underwent LITA+SVG, 2803 (19%) were women and the mean (SD) age was 68 (8.9) years. The median (interquartile range) follow-up time was 9.1 (5.1-12.6) years and 8.1 (4.5-11.7) years for the groups receiving MAG and LITA+SVG, respectively. Compared with LITA+SVG, MAG was associated with reduced mortality rates (hazard ratio [HR], 0.79; 95% CI, 0.72-0.87) and repeated revascularization rates (HR, 0.74; 95% CI, 0.66-0.84) in 15-year follow-up and reduced incidences of myocardial infarction (HR, 0.63; 95% CI, 0.47-0.85) and heart failure (HR, 0.79; 95% CI, 0.64-0.98) in 7-year follow-up. The long-term benefits were coherent by all 3 statistical methods and persisted among patient subgroups with diabetes, obesity, moderately impaired ejection fraction, chronic obstructive pulmonary disease, peripheral vascular disease, or renal disease. Multiple arterial grafting was not associated with increased morbidity or mortality rates at 30 days overall or within patient subgroups.

Conclusions and Relevance

Compared with LITA+SVG, MAG is associated with reduced mortality, repeated revascularization, myocardial infarction, and heart failure among patients with multivessel disease who are undergoing coronary artery bypass grafting without increased mortality or other adverse events at 30 days. The long-term benefits consistently observed across multiple outcomes and subgroups support the consideration of MAG for a broader spectrum of patients who are undergoing coronary artery bypass grafting in routine practice.

Proposed percutaneous aortic valve prosthesis made of cryogel

Transcatheter heart valves are promising for high-risk patients. Generally, their leaflets are made of pericardium stented in a Nitinol basket. Despite their relative success, they are associated with significant complications such as valve migration, implantation risks, stroke, coronary obstruction, myocardial infraction, acute kidney injury (which all are due to the release of detached solid calcific pieces in to the blood stream) and expected issues existing with tissue valves such as leaflet calcification. This study is an attempt to fabricate the first ever polymeric percutaneous valves made of cryogel following the geometry and mechanical properties of porcine aortic valve to address some of the above-mentioned shortcomings. A novel, one-piece, tricuspid percutaneous valve, consisting of leaflets made entirely from the hydrogel, polyvinyl alcohol cryogel reinforced by bacterial cellulose natural nanocomposite, attached to a Nitinol basket was developed and demonstrated. Following the natural geometry of the valve, a novel approach was applied based on the revolution about an axis of a hyperboloid shape. The geometry was modified based on avoiding sharp warpage of leaflets and removal of the central opening orifice area of the valve when valve is fully closed using the finite element analysis. The modified geometry was replaced by a cloud of (control) points and was essentially converted to Bezier surfaces for further adjustment. A cavity mold was then designed and fabricated to form the valve. The fabricated valve was sewn into the Nitinol basket which is covered by Dacron cloth. The models presented in this study merit further development and revisions for both aortic and mitral positions.

Oval housing for the St. Jude Medical bileaflet mechanical heart valve

The St. Jude Medical bileaflet mechanical heart valve was approved by the Food and Drug Administration in late 1970s. The basic idea for the design of the valve is simply two semicircular flat plates pivoting on hinges. The overall performance of St. Jude Medical valves such as blood flow being central, the leaflets opening completely, and the pressure drop across the valve being trivial is satisfactory. St. Jude Medical valves provide an improved hemodynamics compared to the other mechanical heart valve models; however, their non-physiological hemodynamics which may lead to red blood cells lysis and thrombogenicity still remains a major issue. In this study, we hypothesize that applying ovality to the housing might improve their hemodynamics significantly which is based on the fact that the native annulus is oval by nature. A quick but precise numerical model based on the finite strip method was developed by which the regurgitation flow volume and velocity of the proposed design were assessed in the closing phase. The results are satisfactory and an improved hemodynamics is observed. The proposed design can be considered for further numerical and experimental studies and shows promise and merits further development.

Lung Volume Reduction Surgery following Single-Lung Transplantation

Although single-lung transplantation is an established therapy for respiratory failure secondary to emphysema, hyperinflation of the native lung with concomitant compression of the transplanted lung is emerging as a cause of morbidity. In non-transplant emphysematous patients with hyperinflated lungs, pneumectomy was found to improve pulmonary function and quality of life. We report our experience on 5 single-lung transplant recipients with emphysema who underwent lung volume reduction surgery (pneumectomy, bullectomy, or anatomic resection) following transplantation. There were no perioperative deaths. Three patients underwent lung volume reduction because of a progressive symptomatic decline in pulmonary function that was thought to be secondary to hyperinflation of the native lung. Two of these patients had a sustained improvement in lung function and functional status over several years. Two other patients underwent lung volume reduction for removal of suspicious pulmonary nodules in the native lung. Both patients had a subsequent improvement in forced expiratory volume in one second. In our experience, lung volume reduction surgery after single-lung transplantation in emphysematous patients was a safe means of providing long-term improvement in pulmonary function.

Abstract 268: Using Lean Methodology to Reduce Variation in Care of Acute Coronary Syndrome Patients

Background: Regional variation in the utilization of health services is a well-documented phenomenon in health care with numerous studies reporting substantial and unexplained variations in coronary revascularization. In the Canadian province of British Columbia (BC), five cardiac centers provide coronary revascularization services. In 2011 Cardiac Services BC (CSBC) undertook a study that identified substantial regional variation in coronary revascularization that could not be explained by patient characteristics or risk factors. Following this initial project, CSBC launched an initiative to help better understand the regional variations and possibly devise and implement strategies to reduce them.

Methods: Using Lean methodology, we are mapping the key processes of care for ACS patients across BC (initially excluding emergent STEMI and cardiogenic shock) at each cardiac centre. The ACS patient journey will be mapped from admission to discharge through several key decision points that determine whether they will continue through to diagnostic catheterization and revascularization or to be medically managed alone.

The key decision points are:

1. Decision to refer to diagnostic catheterization and subsequent transfer if necessary.

2. Decision to continue to a revascularization procedure (PCI or CABG) after diagnostic catheterization.

The map will summarized these key decision points using multiple sources of data:

1. Flow and patient volumes into and out of each of these decision

2. Times between decision points and key care processes

3. Clinical influencers (ex: standard orders, best practice, established patterns of referral, and consultations) and non-clinical influencers (ex: resource capacity, transportation) that are considered at each decision point (process mapping and interview data).

Discussion: BC is attempting to reduce unexplained variation in coronary revascularization using the Lean methodology to take a systematic approach to the analysis of the process of ACS care across the province. Involving physicians and point of care staff in the detailed mapping process has proven to be a significant step in engaging key stakeholders in the project by allowing input into the process of describing the factors affecting variation of practice at each site. The next step is to convene provincially to determine where to improve standardized practice in order to improve patient outcomes at key points along the value stream.

Effect of heart rate on the hemodynamics of bileaflet mechanical heart valves’ prostheses (St. Jude Medical) in the aortic position and in the opening phase: A computational study

To date, to the best of the authors’ knowledge, in almost all of the studies performed around the hemodynamics of bileaflet mechanical heart valves, a heart rate of 70–72 beats/min has been considered. In fact, the heart rate of ~72 beats/min does not represent the entire normal physiological conditions under which the aortic or prosthetic valves function. The heart rates of 120 or 50 beats/min may lead to hemodynamic complications, such as plaque formation and/or thromboembolism in patients. In this study, the hemodynamic performance of the bileaflet mechanical heart valves in a wide range of normal and physiological heart rates, that is, 60–150 beats/min, was studied in the opening phase. The model considered in this study was a St. Jude Medical bileaflet mechanical heart valve with the inner diameter of 27 mm in the aortic position. The hemodynamics of the native valve and the St. Jude Medical valve were studied in a variety of heart rates in the opening phase and the results were carefully compared. The results indicate that peak values of the velocity profile downstream of the valve increase as heart rate increases, as well as the location of the maximum velocity changes with heart rate in the St. Jude Medical valve model. Also, the maximum values of shear stress and wall shear stresses downstream of the valve are proportional to heart rate in both models. Interestingly, the maximum shear stress and wall shear stress values in both models are in the same range when heart rate is <90 beats/min; however, these values significantly increase in the St. Jude Medical valve model when heart rate is >90 beats/min (up to ~40% growth compared to that of the native valve). The findings of this study may be of importance in the hemodynamic performance of bileaflet mechanical heart valves. They may also play an important role in design improvement of conventional prosthetic heart valves and the design of the next generation of prosthetic valves, such as percutaneous valves.

Hemodynamic study of the elliptic St. Jude Medical valve: A computational study

Despite successful implantation of St. Jude Medical bileaflet mechanical heart valves, red blood cell lysis and thrombogenic complications associated with these types of valves are yet to be addressed. In our previous study, we proposed an elliptic housing where 10% ovality was applied to the housing of St. Jude Medical valves. Our preliminary results suggested that the overall hemodynamic performance of St. Jude Medical valves improved in both the closing and opening phases. In this study, we evaluated the hemodynamics around the leaflets in the opening phase using a more sophisticated computational platform, computational fluid dynamics. Results suggested both lower shear stress and wall shear stress values and an overall improved hemodynamic performance in the proposed design. This improvement is characterized by lower values of shear stress and wall shear stress in the regions downstream of the leaflets, lower pressure drop across the valve and smaller recirculation zones in the sinuses areas. The proposed design may open a new chapter in the concept of design and hemodynamic improvement of the next generation of mechanical heart valves.

Abstract 378: Using Lean Methodology to Reduce Variation in Care of Acute Coronary Syndrome Patients

Background: Regional variation in the utilization of health services is a well-documented phenomenon in health care with numerous studies reporting substantial and unexplained variations in coronary revascularization. In the Canadian province of British Columbia (BC), five cardiac centers provide coronary revascularization services. In 2011 Cardiac Services BC (CSBC) undertook a study that identified substantial regional variation in coronary revascularization that could not be explained by patient characteristics or risk factors. Following this initial project, CSBC launched an initiative to help better understand the regional variations and possibly devise and implement strategies to reduce them. To get a better understanding of the different processes of care/utilization, one of the approaches used is the application of Lean methodology to the care of acute coronary syndrome (ACS) patients.

Methods: Lean methodology is being applied to the patient journey of ACS patients. At each revascularization center Value Steam Maps process maps (VSM) are being prepared through a series of meetings with support, frontline, administrative and clinical staff (see attached example). For each VSM the goal is to identify key decision points in the process of care for ACS patients and to drill down on (Root Cause Analysis) on the decision making environment and criteria used to determine the utilization of coronary revascularization services. Once VSM have been completed they will be compared across sites for similarities and differences. The differences in decision making will then be assessed to determine their effect on variation in utilization across the centers.

Discussion: BC is attempting to reduce unexplained variation in coronary revascularization using the Lean methodology to take a systematic approach to the analysis of the process of ACS care across the province. The next step will be to determine to what extent it is possible to standardize decision making at the key decision points across the HAs. Standardization will be achieved through a mix of best practices, evidence and application of guidelines. While the undertaking is still in the early stages it is expected that it will lead to, at the very least, ACS patients receiving the same care regardless of where they receive their care in BC.

A novel computational model for the hemodynamics of bileaflet mechanical valves in the opening phase

A powerful alternative means to study the hemodynamics of bileaflet mechanical heart valves is the computational fluid dynamics method. It is well recognized that computational fluid dynamics allows reliable physiological blood flow simulation and measurements of flow parameters. To date, in almost all of the modeling studies on the hemodynamics of bileaflet mechanical heart valves, a velocity (mass flow)-based boundary condition and an axisymmetric geometry for the aortic root have been assigned, which, to some extent, are erroneous. Also, there have been contradictory reports of the profile of velocity in downstream of leaflets, that is, in some studies, it is suggested that the maximum blood velocity occurs in the lateral orifice, and in some other studies, it is postulated that the maximum velocities in the main and lateral orifices are identical. The reported values for the peak velocities range from 1 to 3 m/s, which highly depend on the model assumptions. The objective of this study is to demonstrate the importance of the exact anatomical model of the aortic root and the realistic boundary conditions in the hemodynamics of the bileaflet mechanical heart valves. The model considered in this study is based on the St Jude Medical valve in a novel modeling platform. Through a more realistic geometrical model for the aortic root and the St Jude Medical valve, we have developed a new set of boundary conditions in order to be used for the assessment of the hemodynamics of aortic bileaflet mechanical heart valves. The results of this study are significant for the design improvement of conventional bileaflet mechanical heart valves and for the design of the next generation of prosthetic valves.

The occurrence of adverse events in relation to time after registration for coronary artery bypass surgery: a population-based observational study

Background

Our objective was to evaluate the effect of delays on adverse events while waiting for coronary artery bypass grafting (CABG).

Methods

An observational study that prospectively followed patients from registration on a wait list to removal for planned surgery, death while waiting, or unplanned emergency surgery. The population-based registry provided data on 12,030 patients with a record of registration on a wait list for first-time isolated CABG surgery between 1992 and 2005.

Results

In total, 104 patients died and 382 patients underwent an emergency surgery before planned CABG. The death rate was 0.5 per 1000 patient-weeks in the semiurgent group and 0.6 per 1000 patient-weeks the nonurgent group, adjusted OR = 1.07 (95% confidence interval [CI] 0.69—1.65). The emergency surgery rate of 1.2 per 1000 patient-weeks in the nonurgent group was lower compared to 2.1 per 1000 patient-weeks in the semiurgent group (adjusted OR = 0.72, 95% CI 0.54–0.97). However, the nonurgent group had a greater cumulative incidence of preoperative death than the semiurgent group for almost all weeks on the wait list, adjusted OR = 1.92 (95% CI 1.25–2.95). The surgery rate was 1.2 per 1000 patient-weeks in the nonurgent group and 2.1 per 1000 patient-weeks in the semiurgent group, adjusted OR = 0.72 (95% CI 0.54–0.97). The cumulative incidence of emergency surgery before planned CABG was similar in the semiurgent and nonurgent groups, adjusted OR = 0.88, (95% CI 0.64–1.20).

Conclusion

Despite similar death rates in the semiurgent and nonurgent groups, the longer waiting times in the nonurgent group result in a greater cumulative incidence of death on the wait list compared to that in the semiurgent group. These longer waiting times also offset the lower rate of emergency surgery before planned admission in the nonurgent group so that the cumulative incidence of the emergency surgery was similar in both groups.

Delays for coronary artery bypass surgery: how long is too long?

When access to elective surgery is rationed by wait lists, patients requiring coronary artery bypass grafting may have to wait after a decision to operate has been made. The current literature suggests that a long wait for planned surgical revascularization may lead to worsening of symptoms, deterioration in the patient's condition and a less favorable clinical outcome; it may also increase the probability of preoperative death and unplanned emergency admission. Yet there has been little evidence generated by appropriate statistical methodology that bears on the health effects of a delay in undergoing the operation. In this article, we present three potential approaches for summarizing wait-list data. We also discuss the utility of each method for determining the point at which a delay in waiting for coronary artery bypass surgery becomes too long, from the perspectives of hospital managers, surgeons and patients.

Evaluation of supply-side initiatives to improve access to coronary bypass surgery

Background

Guided by the evidence that delaying coronary revascularization may lead to symptom worsening and poorer clinical outcomes, expansion in cardiac surgery capacity has been recommended in Canada. Provincial governments started providing one-time and recurring increases in budgets for additional open heart surgeries to reduce waiting times. We sought to determine whether the year of decision to proceed with non-emergency coronary bypass surgery had an effect on time to surgery.

Methods

Using records from a population-based registry, we studied times between decision to operate and the procedure itself. We estimated changes in the length of time that patients had to wait for non-emergency operation over 14 calendar periods that included several years when supplementary funding was available. We studied waiting times separately for patients who access surgery through a wait list and through direct admission.

Results

During two periods when supplementary funding was available, 1998–1999 and 2004–2005, the weekly rate of undergoing surgery from a wait list was, respectively, 50% and 90% higher than in 1996–1997, the period with the longest waiting times. We also observed a reduction in the difference between 90th and 50th percentiles of the waiting-time distributions. Forty percent of patients in the 1998, 1999, 2004 and 2005 cohorts (years when supplementary funding was provided) underwent surgery within 16 to 20 weeks following the median waiting time, while it took between 27 and 37 weeks for the cohorts registered in the years when supplementary funding was not available. Times between decision and surgery were shorter for direct admissions than for wait-listed patients. Among patients who were directly admitted to hospital, time between decision and surgery was longest in 1992–1993 and then has been steadily decreasing through the late nineties. The rate of surgery among these patients was the highest in 1998–1999, and has not changed afterwards, even for years when supplementary funding was provided.

Conclusions

Waiting times for non-emergency coronary bypass surgery shortened after supplementary funding was granted to increase volume of cardiac surgical care in a health system with publicly-funded universal coverage for the procedure. The effect of the supplementary funding was not uniform for patients that access the services through wait lists and through direct admission.

Differences in myocardial PTEN expression and Akt signalling in type 2 diabetic and nondiabetic patients undergoing coronary bypass surgery

OBJECTIVE

Patients with diabetes experience increased cardiovascular complications after cardiac surgery. Hyperglycaemia predicts increased mortality after myocardial infarction and may influence cardiovascular risk in humans. Impaired prosurvival phosphatase and tensin homologue on chromosome 10 (PTEN)-Akt signalling could be an important feature of the diabetic heart rendering it resistant to preconditioning. This study was designed to evaluate for differences and relationships of myocardial PTEN-Akt-related signalling and baseline glycaemic control marker in type 2 diabetic and nondiabetic patients undergoing coronary artery bypass surgery.

METHODS

Right atrial biopsies and coronary sinus blood were obtained from 18 type 2 diabetic and 18 nondiabetic patients intraoperatively. Expression and phosphorylation of Akt, endothelial nitric oxide synthase (eNOS), Bcl-2 and PTEN were evaluated by Western blot. Plasma 15-F(2t) -isoprostane concentrations were evaluated by liquid chromatography-mass spectrometry.

RESULTS

PTEN expression and 15-F(2t) -isoprostane concentrations were significantly higher in diabetic patients. Increased fasting blood glucose levels correlated with increased coronary sinus plasma 15-F(2t) -isoprostane concentrations. Increased cardiac 15-F(2t) -isoprostane generation was highly correlated with myocardial PTEN expression. Bcl-2 expression and eNOS phosphorylation were significantly lower in diabetic compared with nondiabetic patients. Akt phosphorylation tended to be lower in diabetic patients; however, this tendency failed to reach statistical significance.

CONCLUSION

The current results suggest that prosurvival PTEN-Akt signalling is impaired in the diseased diabetic myocardium. Hyperglycaemia and increased oxidative stress may contribute to this phenomenon. These findings strengthen the understanding of the underlying biologic mechanisms of cardiac injury in diabetic patients, which could facilitate development of new treatments to prevent cardiovascular complications in this high-risk population.

Right-sided endocarditis secondary to a peritoneovenous shunt

A 51-year-old woman with a peritoneovenous shunt for refractory ascites presented with three months of increasing fatigue, exertional dyspnea, night sweats and positive blood cultures. Imaging revealed multiple pulmonary emboli. Transthoracic&nbsp; chocardiography demonstrated moderate tricuspid regurgitation and a large pedunculated right atrial mass attached to the interatrial septum. The echocardiographic appearance remained unchanged after one month of antibiotic therapy and&nbsp; nticoagulation. Intraoperatively, the mass was easily excised and the grossly abnormal tricuspid valve replaced. Pathology revealed endocarditis with multiple bacterial colonies, and fibromyxoid changes consistent with postinflammatory valve disease.

Giant cell arteritis presenting with aortic dissection: two cases and review of the literature

Aortitis is the most serious location of the disease giant cell (temporal) arteritis (GCA). Aortic dissection or the rupture of an aortic aneurysm can be responsible for sudden death among patients with GCA. This report discusses two cases of GCA presenting with aortic dissection. One case had histologically proven giant cell aortitis. The second case was a fatal aortic dissection preceded by a stroke. We describe the main features of aortic dissection and aortitis during GCA, reviewing the existing literature on this subject, and focusing on the requirement of prospective aortic imaging studies to screen patients with this kind of location.

Delay in admission for elective coronary-artery bypass grafting is associated with increased in-hospital mortality

BACKGROUND

Many health care systems now use priority wait lists for scheduling elective coronary artery bypass grafting (CABG) surgery, but there have not yet been any direct estimates of reductions in in-hospital mortality rate afforded by ensuring that the operation is performed within recommended time periods.

METHODS

We used a population-based registry to identify patients with established coronary artery disease who underwent isolated CABG in British Columbia, Canada. We studied whether postoperative survival during hospital admission for CABG differed significantly among patients who waited for surgery longer than the recommended time, 6 weeks for patients needing semi-urgent surgery and 12 weeks for those needing non-urgent surgery.

RESULTS

Among 7316 patients who underwent CABG, 97 died during the same hospital admission, for a province-wide death rate at discharge of 1.3%. The observed proportion of patients who died during the same admission was 1.0% (27 deaths among 2675 patients) for patients treated within the recommended time and 1.5% (70 among 4641) for whom CABG was delayed. After adjustment for age, sex, anatomy, comorbidity, calendar period, hospital, and mode of admission, patients with early CABG were only 2/3 as likely as those for whom CABG was delayed to experience in-hospital death (odds ratio 0.61; 95% confidence interval [CI] 0.39 to 0.96). There was a linear trend of 5% increase in the odds of in-hospital death for every additional month of delay before surgery, adjusted OR = 1.05 (95% CI 1.00 to 1.11).

CONCLUSION

We found a significant survival benefit from performing surgical revascularization within the time deemed acceptable to consultant surgeons for patients requiring the treatment on a semi-urgent or non-urgent basis.

Survival benefit of coronary-artery bypass grafting accounted for deaths in those who remained untreated

Background

Currently there are no direct estimates of mortality reduction afforded by coronary-artery bypass grafting (CABG) that take into account the deaths among patients for whom coronary revascularization was indicated but who did not undergo the treatment. The objective of this analysis was to compare survival after the treatment decision between patients who underwent CABG and those who remained untreated.

Methods

We used a population-based registry to identify patients with established coronary artery disease who were to undergo first-time isolated CABG. We measured the effect of surgical revascularization on survival after the treatment decision in two cohorts of patients categorized by symptoms, coronary anatomy, and left ventricular function.

Results

One in 10 patients died during the five years after treatment decision. The hazard of death among patients who underwent CABG was 51 percent of that for the untreated group, the adjusted hazard ratio was 0.51 (95 percent confidence interval, 0.43 to 0.61). The effect was stronger when CABG was performed within the recommended time: adjusted hazard ratios were 0.43 (95 percent confidence interval, 0.35 to 0.53) and 0.58 (95 percent confidence interval, 0.48 to 0.70) for early and late intervention, respectively; chi-square for the difference between hazard ratios was 12.2 (P < 0.001).

Conclusion

Estimates that account for patients who died before they could undergo a required CABG indicate a significant survival benefit of performing early surgical revascularization even for patients registered to undergo the operation on the non-urgent basis.

Interpretation of Transbronchial Lung Biopsies from Lung Transplant Recipients:Inter- and Intraobserver Agreement

BACKGROUND: Transbronchial lung biopsy results are crucial for the management of lung transplant recipients. Little information is available regarding the reliability and reproducibility of the interpretation of transbronchial lung biopsies.

OBJECTIVE: To examine the inter-reader variability between two lung pathologists with expertise in lung transplantation.

METHODS: Fifty-nine transbronchial lung biopsy specimens were randomly selected. Active infection had been excluded in all cases. The original interpretations (as per the Lung Rejection Study Group) for acute rejection grade included 19 biopsies scored as A0 (none), 14 scored as A1 (minimal), 12 as A2 (mild), 11 as A3 (moderate) and three as A4 (severe). The pathologists worked independently without clinical information or knowledge of the original interpretation. The specimens were graded using the Lung Rejection Study Group criteria for acute rejection (grades A0 to A4), airway inflammation (grades B0 to B4) and bronchiolitis obliterans (C0 absent and C1 present). Between-reader agreement for each category was analyzed using a Kappa statistic.

RESULTS: Because many transplant specialists initiate augmented immunosuppression with biopsy grades of A2 or higher, results for each reader were dichotomized as A0/A1 versus A2/A3/A4. Using this dichotomy, there was only moderate agreement (kappa 0.470, P<0.001) between readers. For categories B and C, the results were dichotomized for the absence or presence of airway inflammation and bronchiolitis obliterans, respectively. The level of agreement between readers was fair for category B (kappa 0.333, P=0.014) and poor for category C (kappa 0.166, P=0.108). The intrareader agreement for acute rejection was substantial (kappa 0.795, P=0.0001; kappa 0.676, P=0.0001).

CONCLUSIONS: Because the agreement between expert pathologists is only modest, optimum clinical decision-making requires that transbronchial lung biopsy results be used in an integrated clinical context.

The mosaic valve clinical performance at seven years: results from a multicenter prospective clinical trial

BACKGROUND AND AIM OF THE STUDY

The Mosaic valve is a third-generation stented porcine bioprosthesis built upon the historical durability of the Hancock II valve in an attempt to improve hemodynamic performance and durability.

METHODS

This multicenter trial was prospective and non-randomized in design. Between February 1994 and October 1999, six centers following a common study protocol enrolled 797 patients (mean age 70 years: range: 21-88 years) who underwent aortic valve replacement (AVR), and 232 patients (mean age 68 years; range: 17-84 years) who underwent mitral valve replacement (MVR). The cumulative follow up was 3,442 patient-years (pt-yr) for AVR (mean 4.3 years; maximum 8 years), and 870 pt-yr for MVR (mean 3.7 years; maximum 7 years). Follow up was complete for 95% of AVR patients, and for 97% of MVR patients.

RESULTS

The mean gradient and calculated effective orifice area average across all valve sizes remained stable at one, four and six years. Freedom from valve-related adverse events (mean +/- SE) at one, four and seven years after AVR were, respectively: Antithromboembolic-related hemorrhage (ARH) 97.0 +/- 0.6, 95.6 +/- 0.9, and 94.6 +/- 5.1%; primary hemolysis 100, 100, and 100%; and structural valve deterioration (SVD) 100, 100 and 100%. Freedom at one, four and seven years after MVR were: ARH 96.9 +/- 1.2, 95.6 +/- 2.0, and 95.6 +/- 7.6%; primary hemolysis 100, 100, and 100%; and SVD 100, 100, and 100%.

CONCLUSION

These mid-term results demonstrate the clinical safety and excellent performance of the Mosaic valve. Continued follow up will determine if this new-design, third-generation bioprosthesis will provide increased durability.

Outcome of mitral valve repair or replacement: a comparison by propensity score analysis

BACKGROUND

There are no randomized trials comparing outcomes after mitral valve (MV) repair and replacement. Propensity scoring is a powerful tool that has the potential to reduce selection bias in nonrandomized studies.

METHODS

From the BC Cardiac Registries, 2,060 patients presented for MV surgery, with or without CABG between 1991 and 2000. We then identified 322 MV repairs who were then matched by propensity score to an equal number of MV replacement patients. We compared survival and freedom from re-operation outcomes using Cox proportional hazards model analysis. Multivariable analysis was then used to compare outcomes in 358 MV repair patients with 352 MV replacement patients who had undergone chordal sparing surgery.

RESULTS

The comparison groups generated using propensity scores were well balanced with respect to all collected baseline risk factors. Median follow-up time was 3.4 years. Patients undergoing MV repair had significantly improved survival (RR 0.46; 95% CI, 0.28 to 0.75) but a trend toward more re-operations (RR 2.11; 95% CI, 1.00 to 4.47) compared with patients undergoing replacement. Mitral valve repair patients still had better survival (RR 0.52; 95% CI, 0.32 to 0.85) compared with MV replacement patients who had undergone chordal sparing surgery.

CONCLUSIONS

We used propensity score methods to reduce selection bias in a population-based cohort of patients undergoing MV repair/replacement. Repair was associated with better survival, but a trend to increased re-operation.

Noninvasive investigations for the early detection of chronic airways dysfunction following lung transplantation

BACKGROUND

The diagnosis of chronic rejection after lung transplantation is limited by the lack of a reliable test to detect airways disease early.

OBJECTIVES

To determine whether maximum midexpiratory flow (MMEF), or changes on high resolution computed tomography (HRCT) or ventilation/perfusion lung (V/Q) scans are sensitive and specific for early detection of bronchiolitis obliterans syndrome (BOS; forced expiratory volume in 1 s [FEV1] less than 80% post-transplant baseline) by evaluating long term survivors of lung transplantation at two sequential time points.

METHODS

Twenty-two stable lung transplant recipients underwent spirometry, HRCT scanning and V/Q scanning 1.6 +/- 0.9 years and 3.1 +/- 1.1 years post-transplant (time points 1 and 2, respectively; mean +/- SD).

RESULTS

Although HRCT was sensitive for the detection of BOS, it lacked specificity, and hence, there were no significant relationships between the presence of BOS and any of the HRCT parameters evaluated at time 1 or time 2. Of the V/Q parameters studied, the presence of heterogeneous perfusion (P=0.04, sensitivity 100%, specificity 33%) and segmental perfusion defects (P=0.04, sensitivity 60%, specificity 83%) were significantly related to BOS, but only at time 2. MMEF less than or equal to 75% post-transplant baseline was significantly related to the presence BOS at time 1 only (P=0.05, sensitivity 100%, specificity 47%). MMEF less than or equal to 75% post-transplant baseline at time 1 was sensitive for the development of BOS at time 2, but was limited by low specificity.

CONCLUSIONS

In this group of lung transplant recipients, HRCT and V/Q scanning, as well as analysis of MMEF, did not add information that was clinically more useful than FEV1 for the early identification of chronic rejection.

Pharmacokinetics and protein binding of mycophenolic acid in stable lung transplant recipients

Mycophenolate mofetil (MMF) use is increasing in solid organ transplantation. Mycophenolic acid (MPA), the active metabolite of MMF, is highly protein bound and only free MPA is pharmacologically active. The average MPA free fraction in healthy adult individuals, stable renal transplant recipients, and heart transplant recipients is approximately 2 to 3%. However, no data are currently available on MPA protein binding in stable lung transplant recipients and little is known regarding MPA's pharmacokinetic characteristics after lung transplantation. The purpose of this study was to characterize the pharmacokinetic profile and protein binding of MPA in this patient population. Seven patients were entered into the study. On administration of a steady-state morning MMF dose, blood samples were collected at 0, 1, 2, 3, 4, 5, 6, 8, 9, 10, and 12 hours post-dose. Total MPA concentrations were measured by a validated HPLC method with UV detection and followed by ultrafiltration of pooled samples for free MPA concentrations. Area under the curve (AUC), peak concentration (Cmax), time to peak concentration (Tmax), trough concentration (Cmin), free fraction (f), and free MPA AUC were calculated by traditional pharmacokinetic methods. Patient characteristics included; 3 males and 4 females, an average of 4.4 years post-lung transplant (range, 0.3-11.5 yr), mean (+/- SD) age of 50 +/- 10 years and weight 69 +/- 20 kg. Mean albumin concentration was 37 +/- 3 g/L and serum creatinine was 142 +/- 49 micromol/L. All patients were on cyclosporine and prednisone. MMF dosage ranged from 1 to 3 g daily (35.5 +/- 14.1 mg/kg/d; range, 15.2-60.0 mg/kg/d). Mean (+/- SD) AUC was 45.78 +/- 18.35 microg.h/mL (range, 16.56-74.22 microg.h/mL), Cmax was 17.37 +/- 7.69 microg/mL (range, 4.92-26.63 microg/mL), Tmax was 1.2 +/- 0.4 hours (range, 1.0-2.0 h), Cmin was 3.12 +/- 1.41 microg/mL (range, 1.47-4.82 microg/mL), f was 2.90 +/- 0.56% (range, 2.00-3.40%), and free MPA AUC was 1.29 +/- 0.50 microg.h/mL (range, 0.54-1.88 microg.h/mL). This is the first study to determine these pharmacokinetic characteristics of MPA in the lung transplant population. Further studies should focus on identification of MMF dosing strategies that optimize immunosuppressive efficacy and minimize toxicity in lung allograft recipients.

Amphotericin B disposition after aerosol inhalation in lung transplant recipients

BACKGROUND

Bronchopulmonary fungal infections continue to be a major cause of morbidity and mortality in lung transplant recipients, and amphotericin B remains the drug of choice for prophylaxis of most fungal infections. Unfortunately, intravenous amphotericin B has numerous serious adverse effects; thus, nebulized amphotericin B could decrease the incidence of adverse effects seen with the intravenous formulation and provide high local concentrations in the lung tissue. We performed a prospective pilot study to characterize the bronchoalveolar lavage (BAL), lung tissue, and plasma concentrations of amphotericin B following inhalation administration to lung transplant recipients.

METHODS

Amphotericin B 30 mg was administered by nebulizer prior to a routine bronchoscopy. Amphotericin B concentrations in BAL samples from the upper and lower lobes, transbronchial biopsies, and plasma (obtained by drawing a blood sample 30 min after the amphotericin B inhalation) were analyzed by HPLC.

RESULTS

Eight patients were enrolled in the study (mean age 50.0 +/- 16.1 y; number of years posttransplant 3.0 +/- 1.9; type of transplant 5 double-lung, 3 single-lung). The mean amphotericin B concentration in the upper and lower lobe BAL samples were 0.68 +/- 0.36 and 0.50 +/- 0.31 microgram/mL, respectively. Amphotericin B concentrations, detected in only 2 of 5 biopsy samples, were 0.118 and 0.03 microgram/g. Amphotericin B was detected in the plasma of only 1 patient (0.19 mg/L).

CONCLUSIONS

This pilot study demonstrated that detectable concentrations of amphotericin B can be attained in both the upper and lower BAL samples following aerosol administration. However, the frequency of the dose and duration of treatment still need to be determined in a larger study.

Impaired exercise performance after successful liver transplantation

BACKGROUND

Recipients of heart, lung, and kidney transplants have impaired peak exercise performance (peak Vo2 40% to 60% predicted, reduced anaerobic threshold [AT]) without evidence of ventilatory or cardiac limitations. The aim of this study was to determine whether similar exercise impairment occurs in liver transplant recipients.

METHODS

We studied eight healthy liver transplant recipients (age 42+/-9 [SD] years, 6 male, 31+/-13 months posttransplant). Immunosuppression included FK506 or cyclosporine, azathioprine or mycophenolate mofetil, and prednisone. Subjects underwent lung function testing and cardiopulmonary exercise testing on a cycle ergometer.

RESULTS

Peak exercise oxygen consumption (Vo2) was 22+/-8 ml/min/kg (66+/-20% predicted maximum). No subject demonstrated exercise desaturation or ventilatory limitation (peak minute ventilation 55+/-8% predicted maximum voluntary ventilation). Peak heart rate was 87+/-8% of predicted maximum. Early AT was evident (1.2+/-0.34 L/min, 48+/-11% predicted Vo2max).

CONCLUSIONS

Liver transplant recipients exhibit impaired peak exercise performance similar to that observed after other solid organ transplants, possibly as a result of chronic deconditioning or myopathy related to immunosuppressive medications.

A limited sampling strategy for cyclosporine area under the curve monitoring in lung transplant recipients

We developed a limited sampling strategy (LSS) for predicting cyclosporine (Neoral) area under the curve from concentration-time data obtained specifically from lung transplant recipients. The optimal and most clinically convenient LSS for lung transplant recipients, based on patient wait time, number of blood samples required, percent prediction error, and assessment of predictive performance is one that requires 2 blood samples collected at 1 and 3 hours post-dose: AUC = 1.75 x C(1) + 4.91 x C(3) + 185.62.

Surgical Closure of Patent Foramen Ovale for Stroke Prevention: Vancouver General Hospital Experience

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Background and Purpose Patent foramen ovale (PFO) is implicated as a potential cause of stroke, particularly in young patients with otherwise cryptogenic events. The natural history, risk of stroke recurrence and optimal secondary stroke prevention remains uncertain. Therapeutic options include long-term antiplatelet therapy, anti-coagulation therapy, and PFO closure by surgery or device. We report the results of 53 patients treated with surgical closure. Methods and Materials We have followed 53 consecutive surgically treated patients (23 men and 30 female). All patients were evaluated by a stroke neurologist, a cardiologist with expertise in adult congenital disease and a cardiovascular surgeon. Patients who met the following criteria were included: 1) embolic TIA or stroke, 2) PFO or PFO and atrial septal aneurysm (ASA), 3) investigations included cerebral angiography, transesophageal echocardiography, and hypercoagulable studies, 4) presumptive clinical diagnosis of paradoxical embolism with no other etiology detected. Follow up was obtained by clinic visit and standardized telephone questionnaire. Results Prior to surgery 27 patients had stroke and 26 had TIAs; 12 had multiple cerebrovascular events. The mean age at symptom onset was 41.8 ± 9.3 yrs (range 19 to 59). 22 patients had an isolated PFO and 31 had both a PFO and an ASA. Average PFO size measured at surgery was 8.8 ± 7.7 mm. 40 were treated with primary closure, 13 with suture and patch closure. Average post-surgical hospital stay was 4 days. There was no surgical mortality or major morbidity. Minor perioperative morbidity occurred in 13 patients. Average follow up postsurgery was 22.2 ± 17.4 months (range 0.7 to 90.8 months). There were no recurrent strokes and 1 recurrent TIA. Conclusions Surgical closure of PFO can be safely performed with low morbidity and mortality. In this group of carefully selected patients, there have been no recurrent strokes. Further studies are necessary to define high-risk patients for recurrent stroke who may benefit from surgical closure.

Treatment of post-transplant lymphoproliferative disease with rituximab monoclonal antibody after lung transplantation

Three patients with diffuse large B-cell type of post-transplant lymphoproliferative disease after lung transplantation were treated with rituximab, an anti-CD20 monoclonal antibody. Treatment resulted in two complete remissions and one non-response.

Recurrence of intravenous talc granulomatosis following single lung transplantation

Advanced pulmonary disease is an unusual consequence of the intravenous injection of oral medications, usually developing over a period of several years. A number of patients with this condition have undergone lung transplantation for respiratory failure. However, a history of drug abuse is often considered to be a contraindication to transplantation in the context of limited donor resources. A patient with pulmonary talc granulomatosis secondary to intravenous methylphenidate injection who underwent successful lung transplantation and subsequently presented with recurrence of the underlying disease in the transplanted lung 18 months after transplantation is reported.

Surgical management of adenocarcinoma of the cardia

BACKGROUND

The incidence of adenocarcinoma of the cardia is increasing. The surgical management remains controversial. The present study reviews our experience with surgically resected adenocarcinoma of the cardia.

METHODS

A retrospective review of 153 cases of surgically resected adenocarcinoma of the cardia was performed. Preoperative radiotherapy was used in 31 patients. The surgical approach, morbidity, mortality, impact of preoperative radiotherapy, and survival were determined.

RESULTS

The type of resection performed was a transhiatal esophagogastrectomy in 78%, a transthoracic esophagogastrectomy in 21%, and a transabdominal esophagogastrectomy in 1%. The in-hospital mortality rate was 4%. The frequency of complications was not associated with the use of preoperative radiotherapy or surgical approach. The 1-year (61%), 2-year (38%), 3-year (23%), and 5-year (16%) survival were not affected by the use of preoperative radiotherapy or surgical approach. Survival was significantly associated with stage and the presence of lymph node metastasis.

CONCLUSIONS

Adenocarcinoma of the cardia is associated with a poor long-term prognosis. The long-term survival does not appear to be affected by the use of preoperative radiotherapy or by surgical approach.

Upper esophageal sphincter myotomy in oculopharyngeal muscular dystrophy: long-term clinical results

From 1980 to 1995, 53 patients with oculopharyngeal muscular dystrophy (OPMD) underwent an upper esophageal sphincter (UES) myotomy for the control of marked dysphagia. From this number, a group of 21 patients had been evaluated for preoperative and postoperative symptoms in 1987. The same clinical assessment was performed in 1995 by an independent evaluator for a total of 37 patients including 12 patients from the first group. As a whole, after a mean follow-up of 6.2 years, surgery succeeded in 18 patients (49%), gave a partial improvement in 12 (32%) and failed in seven (19%). The 12 patients evaluated twice (in 1987 and 1995) have had very good early results, 8-69 months after UES myotomy: dysphagia was totally relieved in eight patients, occurred rarely in three and was moderate in one. Nevertheless, the very long-term follow-up (8 years later) has shown a recurrence of the swallowing and tracheobronchial symptoms in many cases.

Extended lung preservation with platelet-activating factor-antagonist TCV-309 in combination with prostaglandin E1

BACKGROUND

Ischemia-reperfusion injury is one of the major problems in organ transplantation. The role of platelet-activating factor (PAF) in the pathophysiology of ischemia-reperfusion injury and the protective effect of a novel phospholipid PAF analog (TCV-309) alone and combined with prostaglandin E1 (PGE1) is investigated in an extended (20 hours) ex vivo lung preservation.

METHODS

Forty-two swine were divided into three groups. Group A was the control. In groups B and C, the effect of PAF was blocked with TCV-309 administered 1 hour before cross-clamping for donor and recipient. Group C received PGE1 50 micrograms bolus in the donor pulmonary plegia, and the recipients received a 50 micrograms bolus plus 0.003 microgram/kg/min infusion at the time of implantation. Donor lungs were perfused with cold modified Collins solution and maintained in hypothermic storage (4 degrees C) for 20 hours. Hemodynamics, lung mechanics, gas exchange, and biochemistry were assessed before transplantation (donor) and at 30 minutes and 24 hours after reperfusion (recipient). At 24 hours after reperfusion, the histopathologic condition of transplanted lungs was evaluated.

RESULTS

Radioimmunoassay demonstrated a significant (p < 0.001) increase in the production of PAF and TXB2 in transplanted lungs at 24 hours after transplantation for group A only. Hemodynamics, gas-exchange parameters, and lung compliance were significantly (p < 0.05) better after transplantation for groups B and C. Wet lung weight was significantly less (p < 0.05) for group C. Semiquantitative morphometric analysis demonstrated the highest degree of damage for group A compared with groups B and C. A strong correlation (r2 = 70) between lung weight and histologic injury scores was observed among groups.

CONCLUSIONS

This study suggests that PAF is responsible in part for the deleterious effects of ischemia and reperfusion, that PAF-antagonist TCV-309 protects lungs from extended (20 hours) ischemic injury, and that PGE1 seems to have an additional beneficial effect.

Right outflow tract obstruction by a pedunculated neurofibroma: case report and literature review

Right outflow tract obstruction due to neurofibroma is rare, with only four cases identified in the world literature. Obstruction due to a pedunculated neurofibroma has never been reported. A 36-year-old woman with no known heart disease presenting with dyspnea, palpitations and chest pain was shown on echocardiogram to have a mobile right ventricular mass. Cardiac catheterization revealed normal coronary arteries and right ventricular outflow tract obstruction by a pedunculated mass, which was surgically removed and histologically proven to be a benign neurofibroma. Following surgery the patient's symptoms disappeared, with no recurrence three years postoperatively.

[Iatrogenic drug-induced diseases, requiring hospitalization, in patients over 65 years of age. 1-year retrospective study in an internal medicine department]

Iatrogenic pathology is mainly seen in the elderly. In a one year retrospective study, we showed that drug toxicity was responsible for 87 cases requiring hospitalisation in patients aged 65 years and above (7.7% of hospital admission for patients over 65 years). The major manifestations were: 21 cases of sera electrolyte disturbance, 19 concerning gastro-intestinal tract and liver, 16 cardiological disorders, 13 neurological complications, ten involving the endocrine system, six hematological complications. The most common drugs involved were: antihypertensive agents (36%), of which 20.5% were diuretics, psychotherapeutic drugs (24.8%), anti-inflammatory drugs (17.8%). The average cost per patient was calculated to 20,602 FF per patient. Impossibility for direct return to the original dwelling place was another complication in 29% of hospitalisations related to iatrogenic disorders. The high number of drugs taken daily increases the risk of drug interactions which was responsible for iatrogenic accidents in 12.6% of the patients of this study.