Use of a monoblock dual-mobility acetabular component in primary total hip arthroplasty in patients at high risk of dislocation

INTRODUCTION

Dislocation is amongst the most common complications following total hip arthroplasty (THA). Dual-mobility bearings have been suggested as one way to reduce the risk of dislocation, particularly among patients at increased risk. The purpose of this study was to determine the outcomes of a monoblock dual-mobility shell for patients at high risk for dislocation following primary THA.

METHODS

A total of 155 primary THAs with a monoblock, cementless dual-mobility acetabular component were performed in patients at high risk for dislocation. Two patients died prior to their two-year follow-up. The remaining 153 THAs were followed for a mean of 5.1 years (range: 2.1 to 9.3).

RESULTS

There were no dislocations; however, four patients underwent revision surgery: one for an early periprosthetic acetabular fracture, one for an early periprosthetic femoral fracture, one for a late periprosthetic femoral fracture, and one for leg-length discrepancy. Intraoperative complications included one periprosthetic acetabular fracture treated with protected weight-bearing and one intraoperative proximal femoral fracture treated with cerclage wiring. Harris Hip Scores improved from a mean of 42.4 points preoperatively to a mean of 82.4 points postoperatively (p < 0.001). No cups were radiographically loose. At a mean follow-up of 5.1 years, survivorship of the acetabular component was 99.3% (95% CI, 98.1-100%) and survivorship without any reoperation was 97.4% (95% CI, 95.9-100%).

DISCUSSION

Although there were no dislocations in this high-risk population, periprosthetic fractures of the femur and acetabulum were common with the implants utilised.

Influence of Injection Volume on Rate of Subsequent Intervention in Carpal Tunnel Syndrome Over 1-Year Follow-Up

PURPOSE

The optimal volume and dose of corticosteroid injections for treatment of carpal tunnel syndrome (CTS) have not yet been established. It is unknown whether the volume of injectate influences the outcome of carpal tunnel injection. The purpose of this study was to assess whether there is an association between the volume of injectate and subsequent intervention in the treatment of CTS.

METHODS

This study evaluated residents of Olmsted County, MN, who were treated with a corticosteroid injection for CTS between 2001 and 2010. Failure of treatment was the primary outcome, defined as a subsequent intervention: either a second injection or carpal tunnel release within 1 year of initial injection. General estimating equations logistic regression was used to assess the association between injectate volume and rate of treatment failure, adjusting for age, sex, effective dose of steroid, type of steroid injected, electrodiagnostic severity, and the presence of comorbidities such as rheumatoid arthritis, diabetes mellitus, peripheral neuropathy, and radiculopathy.

RESULTS

There were 856 affected hands in 651 patients. A total of 56% (n = 484) of treated hands received subsequent treatment within 1 year. Multivariable analysis showed that a larger injectate volume was significantly associated with reduced rate of treatment failure within 1 year. Rheumatoid arthritis and ultrasound-guided procedures were also associated with a reduced rate of treatment failure, whereas severe electrodiagnostic results were associated with an increased rate of failure.

CONCLUSIONS

This study showed that a larger volume of corticosteroid injection is associated with reduced odds of subsequent intervention after a single corticosteroid injection in CTS. Further research is needed to determine the optimal volume for steroid injections in the treatment of CTS.

TYPE OF STUDY/LEVEL OF EVIDENCE

Prognostic IV.

Factors Associated With Failure of Hip Arthroscopy in Patients With Hip Dysplasia

The purpose of this study was to compare a group of dysplastic hips treated successfully with hip arthroscopy with a group of dysplastic hips treated unsuccessfully with hip arthroscopy to determine (1) preoperative patient characteristics and radiographic parameters and (2) intraoperative findings and treatment associated with outcome. The authors retrospectively reviewed a prospective database of 20 adult patients (17 female, 3 male) with hip dysplasia who underwent primary hip arthroscopy between January 2009 and February 2013. Modified Beck scores to quantify cartilage damage as well as preoperative and postoperative radiographic measurements (including alpha, Tonnis, and lateral center edge angles [LCEAs]) were compared between patients who failed hip arthroscopy (11 patients) and those who did not (9 patients). Failure after hip arthroscopy was defined as a modified Harris hip score of less than 80 or the need for subsequent hip arthroscopy, arthroplasty, or periacetabular osteotomy. The mean follow-up for the successful patients was 58 months (range, 37-82 months), with an average modified Harris hip score of 93 at most recent follow-up. Preoperative radiographs showed a lower mean LCEA (18.0° vs 21.3°; P=.02) in the failure group, and all successes occurred with a LCEA of 17° or greater. The failure group was more likely to have rim resection of greater than 3 mm performed (hazard ratio, 3.53; P=.04). Among the hips with dysplasia undergoing arthroscopic treatment, patients with a poor outcome were more likely to have an LCEA of less than 17° and intraoperative rim resection of greater than 3 mm. Furthermore, the labral repair group did substantially better than the labral debridement group. [Orthopedics. 2018; 41(2):e234-e239.].

Irrigation and Debridement with Component Retention for Acute Infection After Hip Arthroplasty: Improved Results with Contemporary Management

BACKGROUND

There are conflicting data on the results of irrigation and debridement with component retention in patients with acute periprosthetic hip infections. The goals of this study were to examine contemporary results of irrigation and debridement with component retention for acute infection after primary hip arthroplasty and to identify host, organism, antibiotic, or implant factors that predict success or failure.

METHODS

Ninety hips (57 total hip arthroplasties and 33 hemiarthroplasties) were diagnosed with acute periprosthetic hip infection (using strict criteria) and were treated with irrigation and debridement and component retention between 2000 and 2012. The mean follow-up was 6 years. Patients were stratified on the basis of McPherson criteria. Hips were managed with irrigation and debridement and retention of well-fixed implants with modular head and liner exchange (70%) or irrigation and debridement alone (30%). Seventy-seven percent of patients were treated with chronic antibiotic suppression. Failure was defined as failure to eradicate infection, characterized by a wound fistula, drainage, intolerable pain, or infection recurrence caused by the same organism strain; subsequent removal of any component for infection; unplanned second wound debridement for ongoing deep infection; and/or occurrence of periprosthetic joint infection-related mortality.

RESULTS

Treatment failure occurred in 17% (15 of 90 hips), with component removal secondary to recurrent infection in 10% (9 of 90 hips). Treatment failure occurred in 15% (10 of 66 hips) after early postoperative infection and 21% (5 of 24 hips) after acute hematogenous infection (p = 0.7). Patients with McPherson host grade A had a treatment failure rate of 8%, compared with 16% (p = 0.04) in host grade B and 44% in host grade C (p = 0.006). Most treatment failures (12 of 15 failures) occurred within the initial 6 weeks of treatment; failures subsequent to 6 weeks occurred in 3% of those treated with chronic antibiotic suppression compared with 11% of those who were not treated with suppression (hazard ratio, 4.0; p = 0.3).

CONCLUSIONS

The success rate was higher in this contemporary series than in many previous series. Systemic host grade A was predictive of treatment success.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Incidence and long-term follow-up of isolated posterior cruciate ligament tears

PURPOSE

Isolated posterior cruciate ligament (PCL) tears are an uncommon injury. The goals of this study are to (1) determine the population-based incidence of isolated PCL tears, (2) compare the occurrence of secondary meniscal tears or arthritis in patients with PCL deficiency to patients without PCL tears, and (3) evaluate factors associated with long-term sequelae among patients with PCL deficiency.

METHODS

This retrospective study included a population-based incidence cohort of 48 patients with new-onset, isolated PCL tears between 1990 and 2010, as well as an age and sex-matched cohort of individuals without PCL tears. A chart review was performed to collect information related to the initial injury, treatment, and outcomes. Subjects were retrospectively followed to determine the development of subsequent meniscal tears, arthritis, or total knee arthroplasty (TKA).

RESULTS

The age- and sex-adjusted annual incidence of isolated, complete PCL tears was 1.8 (95 % CI 1.3, 2.3) per 100,000. During a mean 12.2-year follow-up, patients with isolated PCL tears had a significantly higher likelihood (HR 6.2, 95 % CI 1.8, 21.2) of symptomatic arthritis compared to individuals without PCL tears. The likelihood of subsequent meniscal tears (HR 2.1, 95 % CI 0.4, 10.7) and TKA (HR 3.2, 95 % CI 0.5, 19.6) was more frequent among patients with PCL tears compared to subjects without PCL tears. Older age at injury was significantly associated with future arthritis (P = 0.003) and TKA (P = 0.02).

CONCLUSION

Isolated PCL tears remain a rare injury with an estimated annual incidence of 2 per 100,000 persons. Patients with isolated PCL tears have a significantly higher risk of symptomatic arthritis than patients without PCL tears. Older age at injury is associated with a higher risk of arthritis and the need for TKA. The results of this study can be used to educate patients about the natural history of isolated PCL tears and provide a baseline of expectations for the future development of arthritis and subsequent meniscal injury following isolated PCL injury.

LEVEL OF EVIDENCE

Retrospective comparative study, Level III.

The Utility of Metal Ion Trends in Predicting Revision in Metal-on-Metal Total Hip Arthroplasty

BACKGROUND

There is a paucity of data examining metal ion levels over time.

METHODS

We retrospectively reviewed 59 patients (69 hips) with an articular surface replacement total hip arthroplasty. We reviewed prerevision cobalt and chromium concentrations over time.

RESULTS

Seventy-one percent of patients who were revised and had multiple ion measurements (12/17) demonstrated increasing cobalt ion levels or elevated ion levels over time. There was a trend toward an elevated risk of revision for increasing cobalt and chromium levels starting at 12 and 4 ppb, respectively; this was significant for chromium levels above 7 ppb (hazard ratio 22.35, P = .001). Similarly, there was a trend toward an elevated risk of pseudotumor formation for increasing cobalt and chromium levels starting at 5 and 2.5 ppb, respectively; this was significant for cobalt levels above 7 ppb (hazard ratio 6.88, P = .027).

CONCLUSION

In this paper, cobalt and chromium levels levels above 5 and 2.5 ppb started to demonstrate an increased risk of ARMD, and should be considered as a lower cutoff for discussion with patients about the potential for future revision.

Effectiveness of Ultrasound-Guided Compared to Blind Steroid Injections in the Treatment of Carpal Tunnel Syndrome

OBJECTIVE

To compare the effectiveness of ultrasound-guided injections to blind injections in the treatment of carpal tunnel syndrome (CTS) in a large community-based cohort.

METHODS

This study evaluated residents of Olmsted County, Minnesota, treated with a corticosteroid injection for CTS between 2001 and 2010. The proportion of patients receiving retreatment and the duration of retreatment-free survival between blind and ultrasound-guided injections were compared. Propensity score matching was used to control for confounding by indication.

RESULTS

In the matched data set consisting of 234 (of 600) hands treated with a blind injection and 87 (of 89) ultrasound-guided injection cases, ultrasound guidance was associated with a reduced hazard of retreatment (hazard ratio 0.59 [95% confidence interval (95% CI) 0.37-0.93]). In addition, ultrasound guidance was associated with 55% reduced odds of retreatment within 1 year compared to blind injections (adjusted odds ratio 0.45 [95% CI 0.24-0.83]).

CONCLUSION

This study indicates that ultrasound-guided injections are more effective in comparison to blind injections in the treatment of CTS.

Procedural intervention for arthrofibrosis after ACL reconstruction: trends over two decades

PURPOSE

Arthrofibrosis is a rare complication after anterior cruciate ligament (ACL) reconstruction. The purpose of this study was to (1) report a population-based incidence of arthrofibrosis (as defined by manipulation under anaesthesia or surgical lysis of adhesions) following ACL injury and reconstruction, (2) identify risk factors associated with development of arthrofibrosis, and (3) report outcomes of intervention for arthrofibrosis.

METHODS

This was a historical cohort study performed in Olmsted County, Minnesota. The Rochester Epidemiology Project (REP) was used to identify a population-based cohort of individuals with new-onset, isolated ACL tears between 1 January 1990 and 31 December 2010. The REP database provides access to all medical records for each resident of Olmsted County, regardless of the facility where the care was delivered. A total of 1841 individuals were identified with new-onset, isolated ACL tears and were confirmed with chart review. The intervention incidence for arthrofibrosis was then calculated, and various predictive factors including age, sex, calendar year, and meniscal injury were investigated.

RESULTS

During follow-up, 5 patients (1.0 %) in the non-operative cohort and 23 patients (1.7 %) in the ACL reconstruction cohort received intervention for arthrofibrosis, corresponding to an incidence of 0.7 per 1000 person-years in the non-operative cohort and 1.9 per 1000 person-years in the ACL reconstruction cohort. Female patients were 2.5 times more likely to have arthrofibrosis than males. The mean preoperative range of motion was -8° to 83° and improved to a mean of -2° to 127° post-operatively.

CONCLUSIONS

Arthrofibrosis remains a rare but potentially devastating complication after ACL reconstruction, and roughly 2 % of patients had post-operative stiffness that required intervention. Female patients are at higher risk of arthrofibrosis. However, when patients develop severe motion complications after ACL injury, interventions are generally effective in preventing permanent arthrofibrosis.

Are Short-term Outcomes of Hip Arthroscopy in Patients 55 Years and Older Inferior to Those in Younger Patients?

BACKGROUND

Hip arthroscopy for young patients with femoroacetabular impingement (FAI) has been successful, but the efficacy of hip arthroscopy in older patients is not clearly defined.

PURPOSE

To evaluate the clinical outcomes of patients 55 years and older who are undergoing hip arthroscopy and to compare outcomes with those of patients younger than 55 years.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A total of 201 (63 male, 138 female) patients undergoing primary hip arthroscopy for FAI without radiographic arthritis (Tönnis grade <3) were isolated from a prospective database and stratified by age to <55-year and ≥55-year groups. Patients were evaluated preoperatively and 1 and 2 years postoperatively using the modified Harris Hip Score (mHHS) and Hip Outcome Score (HOS: functional scores, as well as Activities of Daily Living [ADL] and Sport subscales). A Wilcoxon signed rank sum test was used to evaluate the differences in outcome scores between the cohorts at each interval.

RESULTS

The <55-year group included 174 patients (mean age, 37 ± 12 years), and the ≥55-year group included 27 patients (mean age, 61 ± 5 years). The minimum follow-up time was 2 years in each group. Preoperative Tönnis grades and mHHS scores (59 vs 59; P = .75) were similar between groups. The ≥55-year cohort underwent labral debridement more frequently (78% vs 36%; P =.02) and were more likely to have full-thickness cartilage defects (22% vs 4%; P = .04). Despite this, the mHHS in both groups improved significantly from baseline, without significant differences at 1 year (86 [≥55 years] vs 81 [<55 years]; P = .53) or 2 years (73.88 [≥55 years] vs 79.54 [<55 years]; P = .06). However, at a minimum 2-year follow-up, patients <55 years had significant improvements over patients ≥55 years in the HOS subscales for ADL score (85.6 vs 75.2; P = .03), ADL rating (80.1 vs 70.0; P = .004), Sport score (70.2 vs 55.6; P = .04), and Sport rating (70.2 vs 58.0; P = .04).

CONCLUSION

Although younger patients had superior HOS outcomes reported at 2 years compared with older patients after hip arthroscopy for FAI, both groups had significant improvement compared with their baseline. These data suggest that carefully selected patients 55 years and older without radiographic arthritis may benefit from hip arthroscopy.

Intravenous Tranexamic Acid Decreases Allogeneic Transfusion Requirements in Periacetabular Osteotomy

Bernese (Ganz) periacetabular osteotomy is associated with significant blood loss and the need for perioperative transfusion. Tranexamic acid decreases blood loss and minimizes transfusion rates in total joint arthroplasty. However, no reports have described its use in patients undergoing Bernese periacetabular osteotomy. This study reports the use of intravenous tranexamic acid in these patients. The study included 137 patients (150 hips) who underwent isolated periacetabular osteotomy at a single institution between 2003 and 2014. Of these, 68 patients (75 hips) received intravenous tranexamic acid 1 g at the time of incision and 1 g at the time of closure. A group of 69 patients (75 hips) served as control subjects who underwent periacetabular osteotomy without administration of intravenous tranexamic acid. Thromboembolic disease was defined as deep venous thrombosis or pulmonary embolism occurring within 6 weeks of surgery. Outcomes measured included transfusion requirements, pre- and postoperative hemoglobin values, operative times, and thromboembolic disease rates. Aspirin was used as the thromboembolic prophylactic regimen in 95% of patients. The rate of allogeneic transfusion was 0 in the tranexamic acid group compared with 21% in the control group (P=.0001). No significant difference was found in the autologous cell salvage requirement (.96 vs 1.01; P=.43) or the thromboembolic disease rate between the tranexamic acid group and the control group (2.67% vs 1.33%; P=.31). The use of intravenous tranexamic acid led to a decreased transfusion requirement with no increased risk of thromboembolic disease in this contemporary cohort of patients undergoing periacetabular osteotomy.

Is Anterior Cruciate Ligament Reconstruction Effective in Preventing Secondary Meniscal Tears and Osteoarthritis?

BACKGROUND

Reconstruction of anterior cruciate ligament (ACL) tears may potentially prevent the development of secondary meniscal injuries and arthritis.

PURPOSE/HYPOTHESIS

The purpose of this study was to (1) evaluate the protective benefit of ACL reconstruction (ACLR) in preventing subsequent meniscal tears or arthritis, (2) determine if earlier ACLR (<1 year after injury) offers greater protective benefits than delayed reconstruction (≥1 year after injury), and (3) evaluate factors predictive of long-term sequelae after ACLR. The hypothesis was that the incidence of secondary meniscal tears, arthritis, and total knee arthroplasty (TKA) would be higher in patients treated nonoperatively after ACL tears than patients treated with surgical reconstruction.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

This retrospective study included a population-based incidence cohort of 964 patients with new-onset, isolated ACL tears between 1990 and 2000 as well as an age- and sex-matched cohort of 964 patients without ACL tears. A chart review was performed to collect information related to the initial injury, treatment, and outcomes. A total of 509 patients were treated with early ACLR, 91 with delayed ACLR, and 364 nonoperatively. All patients were retrospectively followed (range, 2 months to 25 years) to determine the development of subsequent meniscal tears, arthritis, or TKA.

RESULTS

At a mean follow-up of 13.7 years, patients treated nonoperatively after ACL tears had a significantly higher likelihood of developing a secondary meniscal tear (hazard ratio [HR], 5.4; 95% CI, 3.8-7.6), being diagnosed with arthritis (HR, 6.0; 95% CI, 4.3-8.4), and undergoing TKA (HR, 16.7; 95% CI, 5.0-55.2) compared with patients treated with ACLR. Similarly, patients treated with delayed ACLR had a higher likelihood of developing a secondary meniscal tear (HR, 3.9; 95% CI, 2.2-6.9) and being diagnosed with arthritis (HR, 6.2; 95% CI, 3.4-11.4) compared with patients treated with early ACLR. Age >21 years at the time of injury, articular cartilage damage, and medial/lateral meniscal tears were predictive of arthritis after ACLR.

CONCLUSION

Patients treated with ACLR have a significantly lower risk of secondary meniscal tears, symptomatic arthritis, and TKA when compared with patients treated nonoperatively after ACL tears. Similarly, early ACLR significantly reduces the risk of subsequent meniscal tears and arthritis compared with delayed ACLR.

Incidence of Anterior Cruciate Ligament Tears and Reconstruction: A 21-Year Population-Based Study

BACKGROUND

The incidence of isolated anterior cruciate ligament (ACL) tears in the general population is not well defined.

PURPOSE/HYPOTHESIS

The purpose of this study was to define the population-based incidence of ACL tears, describe trends in ACL injuries over time, and evaluate changes in the rate of surgical management. The hypothesis was that the incidence of ACL injury and the rate of subsequent ACL reconstruction increase over time.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

The study population included 1841 individuals who were diagnosed with new-onset, isolated ACL tears (without concomitant ligament injury that required surgery) between January 1, 1990, and December 31, 2010. The complete medical records were reviewed to confirm diagnosis and to extract injury and treatment details. Age- and sex-specific incidence rates were calculated and adjusted to the 2010 US population. Poisson regression analyses were performed to examine incidence trends by age, sex, and calendar period.

RESULTS

The overall age- and sex-adjusted annual incidence of ACL tears was 68.6 per 100,000 person-years. Incidence was significantly higher in male patients than in females (81.7 vs 55.3 per 100,000, P < .001). The incidence of isolated ACL tears decreased significantly over time in males (P < .001) but remained relatively stable in females. Age-specific patterns differed in male and female patients, with a peak in incidence (241.0 per 100,000) between 19 and 25 years in males and a peak in incidence (227.6 per 100,000) between 14 and 18 years in females. The rate of ACL reconstruction increased significantly over time in all age groups (P < .001).

CONCLUSION

With an annual incidence of 68.6 per 100,000 person-years, isolated ACL tears remain a common orthopaedic injury. Differences in age-specific incidence trends in male and female patients may potentially reflect differences in sports participation patterns through the high school and college years. The significant increase in the rate of ACL reconstruction over time may reflect changing surgical indications or an increasing desire among patients to return to high levels of activity after ACL injury.

Incidence of and Factors Associated With the Decision to Undergo Anterior Cruciate Ligament Reconstruction 1 to 10 Years After Injury

BACKGROUND

Among patients treated nonoperatively for 1 year after anterior cruciate ligament (ACL) disruption, little is known about the frequency of ACL reconstruction within the first year of injury and the effect of age range, sex, and meniscal tears on the incidence of ACL reconstruction between 1 and 10 years after injury.

PURPOSE

To (1) define the rate of delayed ACL reconstruction (between 1 and 10 years after injury) in a population-based cohort of isolated ACL tears and (2) evaluate predictive factors associated with delayed reconstruction.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

The study included a population-based cohort of 1841 patients with new-onset, isolated ACL tears that occurred between January 1, 1990, and December 31, 2010. The complete medical records were reviewed to confirm diagnosis and collect data on clinical characteristics and details of subsequent ACL surgery. To evaluate the incidence of ACL reconstruction between 1 and 10 years after injury, landmark survival analysis was performed with a landmark set at 1 year after injury. Early and late predictors of ACL reconstruction were analyzed using Cox proportional hazards regression.

RESULTS

A total of 661 patients were treated nonoperatively for the first year after ACL tears. Over a mean 10 years of follow-up, 213 patients (32%) underwent ACL reconstruction between 1 and 10 years after injury. Young age (hazard ratio [HR], 0.55 per decade increase in age; 95% CI, 0.48-0.62) and meniscal tear at injury (HR, 1.48; 95% CI, 1.12-1.95) were significant predictors of undergoing delayed reconstruction. The rate of delayed ACL reconstruction decreased significantly over the study period (P < .03). There was no association between sex (HR, 0.89; 95% CI, 0.67-1.16) and delayed ACL reconstruction. Among patients who had delayed ACL reconstruction, 40% experienced a secondary meniscal tear before surgery.

CONCLUSION

In this study population of 1841 patients, 62% of patients received ACL reconstruction within 1 year of injury. Of patients treated nonoperatively for 1 year after ACL tears, 32% underwent delayed ACL reconstruction. Predictors of reconstruction beyond 1 year were young age (50% reduction in reconstruction per decade increased age) and baseline meniscal tear. Sex was not predictive for reconstruction beyond 1 year from injury.

Health Care Utilization and Direct Medical Costs of Tennis Elbow: A Population-Based Study

Background:

Tennis elbow is commonly encountered by physicians, yet little is known about the cost of treating this condition.

Hypothesis:

The largest cost associated with treating tennis elbow is procedural intervention.

Study Design:

Descriptive epidemiology study.

Level of Evidence:

Level 4.

Methods:

This retrospective population-based study reviewed patients who were treated for new-onset tennis elbow between January 1, 2003 and December 31, 2012. All patients were followed up through their medical and administrative records to identify health care encounters and interventions for tennis elbow. Unit costs for each health service/procedure were adjusted to nationally representative unit costs in 2013 inflation-adjusted dollars.

Results:

In a cohort of 931 patients who had 2 or more clinical encounters for new-onset lateral epicondylosis during a 12-month period after initial diagnosis, 62% received a median of 3 physical therapy sessions (cost, $100/session) and 40% received a median of 1 steroid injection (cost, $82/injection). Only 4% of patients received surgical intervention with mean costs of $4000. The mean (median) total direct medical cost of services related to lateral epicondylosis for the entire cohort was $660 ($402) per patient over the 1-year period after diagnosis. Patients who continued to be treated conservatively between 6 and 12 months after diagnosis incurred relatively low median costs of $168 per patient.

Conclusion:

In this cohort, a second encounter with a physician for tennis elbow was a strong predictor of increased treatment cost due to a higher likelihood of specialist referral, use of physical therapy, or treatment with steroid injection.

Clinical Relevance:

The majority of direct medical spending on tennis elbow occurs within the first 6 months of treatment, and relatively little expense occurs between 6 and 12 months after diagnosis unless a patient undergoes surgical intervention.

The epidemiology and health care burden of tennis elbow: a population-based study

BACKGROUND

Lateral elbow tendinosis (epicondylitis) is a common condition both in primary care and specialty clinics.

PURPOSE

To evaluate the natural history (ie, incidence, recurrence, and progression to surgery) of lateral elbow tendinosis in a large population.

STUDY DESIGN

Descriptive epidemiology study.

METHODS

The study population comprised a population-based incidence cohort of patients with new-onset lateral elbow tendinosis between January 1, 2000, and December 31, 2012. The medical records of a 10% random sample (n=576) were reviewed to ascertain information on patient and disease characteristics, treatment modalities, recurrence, and progression to surgery. Age- and sex-specific incidence rates were calculated and adjusted to the 2010 US population.

RESULTS

The age- and sex-adjusted annual incidence of lateral elbow tendinosis decreased significantly over time from 4.5 per 1000 people in 2000 to 2.4 per 1000 in 2012 (P<.001). The recurrence rate within 2 years was 8.5% and remained constant over time. The proportion of surgically treated cases within 2 years of diagnosis tripled over time, from 1.1% during the 2000-2002 time period to 3.2% after 2009 (P<.00001). About 1 in 10 patients with persistent symptoms at 6 months required surgery.

CONCLUSION

The decrease in incidence of lateral elbow tendinosis may represent changes in diagnosis patterns or a true decrease in disease incidence. Natural history data can be used to help guide patients and providers in determining the most appropriate course at a given time in the disease process. The study data suggest that patients without resolution after 6 months of onset may have a prolonged disease course and may need surgical intervention.

Characterisation of immune responses in healthy foals when a multivalent vaccine protocol was initiated at age 90 or 180 days

REASONS FOR PERFORMING STUDY

Protection from infectious disease requires antigen-specific immunity. In foals, most vaccine protocols are delayed until 6 months to avoid maternal antibody interference. Susceptibility to disease may exist prior to administration of vaccination at age 4-6 months.

OBJECTIVES

The aim of this investigation was to characterise immune activation among healthy foals in response to a multivalent vaccine protocol and compare immune responses when foals were vaccinated at age either 90 or 180 days.

STUDY DESIGN

Randomised block design.

METHODS

Twelve healthy foals with colostral transfer were blocked for age and randomly assigned to vaccination at age 90 days (treatment) or at age 180 days (control). Vaccination protocols included a 3-dose series and booster vaccine administered at age 11 months.

RESULTS

Immune response following vaccination at age 90 or 180 days was comparable for several measures of cellular immunity. Antigen specific CD4+ and CD8+ expression of interleukin-4, interferon-γ and granzyme B to eastern equine encephalomyelitis, western equine encephalomyelitis, West Nile virus, tetanus toxoid, equine influenza and equine herpesvirus-1/4 antigens were evident for both groups 30 days after initial vaccine and at age 344 days. Both groups showed a significant increase in antigen-specific immunoglobulin G expression following booster vaccine at age 11 months, thereby indicating memory immune responses.

CONCLUSIONS

The data presented in this report demonstrate that young foals are capable of immune activation following a 3-dose series with a multivalent vaccine, despite presence of maternal antibodies. Although immune activation does not automatically confer protection, several of the immune indicators measured showed comparable expression in foals vaccinated at 3 months relative to control foals vaccinated at age 6 months. In high-risk situations where immunity may be required earlier than following a conventional vaccine series, our data provide evidence that foals respond to immunisation initiated at 3 months in a comparable manner to foals initiated at an older age.

NICE thromboprophylaxis guidelines are not associated with increased pericardial effusion after surgery of the proximal thoracic aorta

INTRODUCTION

In 2010 the National Institute for Health and Clinical Excellence (NICE) released guidelines on venous thromboembolism. Strategy focused on risk assessment, antiembolic stockings, sequential compression devices, subcutaneous high dose enoxaparin (40 mg), early mobilisation and hydration. The 40 mg enoxaparin dose over the previous 20 mg regimen was worrisome, and its effect on pericardial effusion rates and mortality in proximal aortic surgery was investigated.

METHODS

Proximal aortic reconstructions performed between December 2008 and April 2011 were identified from prospectively collected data in a tertiary centre database. Retrospective analysis of patient notes was performed. Proximal aortic surgery patients were categorised as low dose (20 mg) enoxaparin and high dose (40 mg) enoxaparin, and compared for confounding variables. In-hospital, early and one-year readmission rates for pericardial effusion were ascertained from echocardiography reports. The primary outcome was total pericardial effusion rate. Secondary outcomes consisted of 30-day and 1-year mortality.

RESULTS

A total of 198 patients underwent proximal thoracic aortic surgery. Nine patients were excluded due to early postoperative death (n=5) and missing patient records (n=4). This left 189 cases for analysis. There were 93 patients in the low dose group and 96 in the high dose group. Groups were comparable for age, cardiopulmonary bypass time, aortic cross-clamp time, postoperative warfarin and antiplatelet agents. Pericardial effusion rates up to one year were comparable (low dose 19% vs high dose 21%). Thirty-day mortality was lower in the low dose group (0 vs 3 deaths). There were four deaths up to one year but these were not attributable to increased enoxaparin.

CONCLUSIONS

Increased perioperative thromboprophylaxis dosage does not increase pericardial effusion rates or mortality in proximal aortic surgery.

Effects of concurrent response-independent reinforcement on fixed-interval schedule performance

In three experiments, behavior maintained by fixed-interval schedules changed when response-independent reinforcement was delivered concurrently according to fixed- or variable-time schedules. In Experiment I, a pattern of positively accelerated responding during fixed interval was changed to a linear pattern when response-independent reinforcement occurred under a variable-time schedule. Overall response rates (total responses/total time) decreased as the frequency of response-independent reinforcement increased. Experiment II showed that the response-rate changes in the first experiment were controlled by the response-reinforcer relation, but the changes in patterns of responding were similar whether concurrently available reinforcement at varying times was response-dependent or response-independent. In the final experiment, the addition of response-independent reinforcement at fixed times to a fixed-interval schedule resulted in changes in both local and overall response rates and in the occurrence of positively accelerated responding between reinforcements. These results suggest that the temporal distribution of reinforcers determines response patterns and that both the response-reinforcement dependency and the schedule of reinforcement determine overall response rates during concurrently scheduled response-dependent and response-independent reinforcement.

Influence of concomitant coronary artery bypass graft on outcome of surgery of the ascending aorta/arch

BACKGROUND

Surgery of the ascending aorta with or without arch is being performed in an increasingly elderly population with risks of coexisting coronary artery disease.

AIM

To define specific groups requiring coronary artery bypass graft (CABG) and to analyse the influence of concomitant CABG on outcome.

DESIGN

Over a 10-year period in a single institution, 296 consecutive procedures on the ascending aorta with or without arch were carried out in 291 patients. CABG was required in 42 (14.2%) procedures. In 24 (57%) patients, CABG was planned preoperatively and in 18 (43%) patients, on a salvage basis.

RESULTS

In-hospital mortality for patients undergoing concomitant CABG was higher (21.4% v 11%, p<0.06). Adjusting for baseline and operative characteristics, this was attributable to operative priority, and was not a consequence of concomitant CABG (adjusted OR 0.30, 95% CI 1.1 to 8.31; p = 0.48). However, in-hospital mortality was significantly higher when CABG was performed as salvage rather than as a planned procedure (38.9% v 8.9%, p = 0.025), and this difference remained after adjusting for confounding variables (adjusted OR 16.2, 95% CI 1.03 to >200; p = 0.047). The 3-year survival was significantly lower with concomitant CABG (59% v 81.9%, p<0.001).

CONCLUSIONS

In association with surgery of the ascending aorta with or without arch planned concomitant CABG did not entail any added operative risk. However, salvage CABG, which occurred almost exclusively in association with emergency cases, was associated with a higher early mortality. Patients needing concomitant CABG had worse survival at 3 years compared with those requiring isolated surgery of the ascending aorta with or without arch.

Early and mid-term outcomes of surgery of the ascending aorta/arch: is there a relationship with caseload?

OBJECTIVES

The relationship between caseload and early outcome remains a subject for debate in cardiac surgery. Surgery of the thoracic aorta is an area of specialist expertise within the adult cardiac surgical field. There is, however, a conflict between the concentration of expertise and the provision of effective emergency cover. This study evaluates the early and mid-term outcomes of patients undergoing surgery of the ascending aorta/aortic arch in a single institution and compares the results of a single higher volume surgeon with lower volume operators.

METHODS

From March 1992 till August 2003, 296 procedures were carried out on 291 patients (aged 17-80, median 62) who underwent operations for replacement of the ascending aorta/aortic arch. One hundred and thirty procedures were carried out by the higher volume surgeon and 160 by one of the six lower volume surgeons (range 10-57). Emergency operation was performed in 138 (47%) patients. One or more other associated cardiac procedures were carried out in 65 patients (22%).

RESULTS

The overall early mortality was 37 (12.5%). After adjustment for baseline differences, era and surgical risk/complexity, the risk of in-hospital death was lower in the higher volume group, but not significantly so. For survival to 3 years the overall risk of death was significantly lower for patients in the higher volume group (hazard ratio 0.72; 95% CI 0.54-0.95) Apart from post-operative renal failure no other significant differences between the two groups were observed.

CONCLUSIONS

Elective surgery of the ascending aorta/arch was associated with low mortality. Outcomes after emergency surgery conformed to contemporary expectations. Only limited differences were identified both with respect to the case profile and early clinical outcomes. Better outcomes in the mid-term in the higher volume group persisted despite adjustment for differences in caseload and are worthy of further study. We believe that these data support our hypothesis that dissemination of appropriate techniques among a group of surgeons represents the most practical method of service provision.

A multi-centre randomised controlled trial of minimally invasive direct coronary bypass grafting versus percutaneous transluminal coronary angioplasty with stenting for proximal stenosis of the left anterior descending coronary artery

OBJECTIVES

To compare the clinical- and cost-effectiveness of minimally invasive direct coronary artery bypass grafting (MIDCAB) and percutaneous transluminal coronary angioplasty (PTCA) with or without stenting in patients with single-vessel disease of the left anterior descending coronary artery (LAD).

DESIGN

Multi-centre randomised trial without blinding. The computer-generated sequence of randomised assignments was stratified by centre, allocated participants in blocks and was concealed using a centralised telephone facility.

SETTING

Four tertiary cardiothoracic surgery centres in England.

PARTICIPANTS

Patients with ischaemic heart disease with at least 50% proximal stenosis of the LAD, suitable for either PTCA or MIDCAB, and with no significant disease in another vessel.

INTERVENTIONS

Patients randomised to PTCA had local anaesthetic and underwent PTCA according to the method preferred by the operator carrying out the procedure. Patients randomised to MIDCAB had general anaesthetic. The chest was opened through an 8-10-cm left anterior thoracotomy. The ribs were retracted and the left internal thoracic artery (LITA) harvested. The pericardium was opened in the line of the LAD to confirm the feasibility of operation. The distal LITA was anastomosed end-to-side to an arteriotomy in the LAD. All operators were experienced in carrying out MIDCAB.

MAIN OUTCOME MEASURES

The primary outcome measure was survival free from cardiac-related events. Relevant events were death, myocardial infarction, repeat coronary revascularisation and recurrence of symptomatic angina or clinical signs of ischaemia during an exercise tolerance test at annual follow-up. Secondary outcome measures were complications, functional outcome, disease-specific and generic quality of life, health and social services resource use and their costs.

RESULTS

A total of 12,828 consecutive patients undergoing an angiogram were logged at participating centres from November 1999 to December 2001. Of the 1091 patients with proximal stenosis of the LAD, 127 were eligible and consented to take part; 100 were randomised and the remaining 27 consented to follow-up. All randomised participants were included in an intention-to-treat analysis of survival free from cardiac-related events, which found a non-significant benefit from MIDCAB. Cumulative hazard rates at 12 months were estimated to be 7.1 and 9.2% for MIDCAB and PTCA, respectively. There were no important differences between MIDCAB and PTCA with respect to angina symptoms or disease-specific or generic quality of life. The total NHS procedure costs were 1648 British pounds and 946 British pounds for MIDCAB and PTCA, respectively. The costs of resources used during 1 year of follow-up were 1033 British pounds and 843 British pounds, respectively.

CONCLUSIONS

The study found no evidence that MIDCAB was more effective than PTCA. The procedure costs of MIDCAB were observed to be considerably higher than those of PTCA. Given these findings, it is unlikely that MIDCAB represents a cost-effective use of resources in the reference population. Recent advances in cardiac surgery mean that surgeons now tend to carry out off-pump bypass grafting via a sternotomy instead of MIDCAB. At the same time, cardiologists are treating more patients with multi-vessel disease by PTCA. Future primary research should focus on this comparison. Other small trials of PTCA versus MIDCAB have now finished and a more conclusive answer to the original objective could be provided by a systematic review.

Treatment of an aortic fungal false aneurysm by composite stentless porcine/pericardial conduit: a case report

Fungal prosthetic valve endocarditis is an uncommon but serious condition with high early and long-term mortality. The majority of these cases occur after aortic valve surgery and are caused by Candida species. Radical debridement of all infected tissues, valve replacement with perioperative and long-term anti-fungal agents is the recommended treatment. Choice of prosthesis varies widely among surgeons, but present recommendations favour biological prostheses. We report for the first time the case of a fungal PVE with false aneurysm after composite aortic root replacement with a dacron composite conduit treated successfully with aortic root replacement using a Shelhigh (Shelhigh Inc., Millburn, NJ) stentless porcine pericardial valved conduit.

Myocardial injury in hypertrophic hearts of patients undergoing aortic valve surgery using cold or warm blood cardioplegia

OBJECTIVES

Myocardial protection techniques during cardiac surgery have been largely investigated in the clinical setting of coronary revascularisation. Few studies have been carried out on patients with left ventricular hypertrophy where the choice of delivery, and temperature of cardioplegia remain controversial. This study investigates metabolic changes and myocardial injury in hypertrophic hearts of patients undergoing aortic valve surgery using antegrade cold or warm blood cardioplegia.

METHODS

Thirty-five patients were prospectively randomised to intermittent antegrade cold or warm blood cardioplegia. Left ventricular biopsies were collected at 5min following institution of cardiopulmonary bypass, 30min after cross-clamping the aorta and 20min after cross-clamp removal, and used to determine metabolic changes during surgery. Metabolites (adenine nucleotides, amino acids and lactate) were measured using high pressure liquid chromatography and enzymatic techniques. Postoperative myocardial troponin I release was used as a marker of myocardial injury.

RESULTS

Ischaemic arrest was associated with significant increase in lactate and alanine/glutamate ratio only in the warm blood group. During reperfusion, alanine/glutamate ratio was higher than preischaemic levels in both groups, but the extent of the increase was considerably greater in the warm blood group. Troponin I release was markedly (P<0.05, Mean+/-SD) lower at 1, 24 and 48h postoperatively in the cold compared to the warm blood group (0.51+/-0.37, 0.37+/-0.22 and 0.27+/-0.19 vs. 0.75+/-0.42, 0.73+/-0.51 and 0.54+/-0.38ng/ml for cold vs. warm group, respectively).

CONCLUSIONS

Cold blood cardioplegia is associated with less ischaemic stress and myocardial injury compared to warm blood cardioplegia in patients with aortic stenosis undergoing valve replacement surgery. Both cardioplegic techniques, however, confer sub-optimal myocardial protection.

Clinical and angiographic outcome of different surgical strategies of bilateral internal mammary artery grafting

Long-term survival, relief of angina, and prevention of myocardial infarction after coronary revascularization are related to the preoperative status of the patient, progression of coronary artery atherosclerosis, and the patency of the conduits used. The increased use of the internal mammary artery for coronary grafting depends upon the accumulation of data on superior late patency compared with venous conduits. These data have supported the simultaneous use of both left and right internal mammary arteries with reported improved late survival. However, controversy still surrounds the clinical and angiographic outcomes of some of the surgical strategies of bilateral internal mammary artery grafting. This review examines a range of surgical strategies of bilateral internal mammary artery grafting and their mid- and long-term clinical and angiographic outcomes. From the available data, careful preoperative selection of patients is paramount. Clinical and angiographic outcome of bilateral internal mammary grafting is superior to single internal mammary grafting with supplemental vein grafts when pedicled, sequential, or free aorto-coronary internal mammary artery is used. Further studies are needed to evaluate the midterm and long-term clinical and angiographic outcomes of complex strategies such as Y or T procedures.

Hemodynamic performance of the 21-mm Sorin Bicarbon mechanical aortic prostheses using dobutamine Doppler echocardiography

BACKGROUND

Small-sized mechanical aortic prostheses are commonly associated with generation of high transvalvular gradients, particularly in patients with large body surface area, and can result in patient-prosthesis mismatch. This study evaluates the hemodynamic performance of 21-mm Sorin Bicarbon bileaflet mechanical prostheses using dobutamine stress echocardiography.

METHODS

Fourteen patients (7 women; mean age, 63+/-8 years) who had undergone aortic valve replacement with a 21-mm Sorin Bicarbon bileaflet mechanical prosthesis 32.4+/-5.1 months previously were studied. After a resting Doppler echocardiogram, a dobutamine infusion was started at a rate of 5 microg x kg(-1) x min(-1) and increased to 30 microg x kg(-1) x min(-1) at 15-minute intervals. Pulsed- and continuous-wave Doppler echocardiographic studies were performed at rest and at the end of each increment of dobutamine. Both peak and mean velocity and pressure gradient across the prostheses were measured, and effective orifice area, discharge coefficient, and performance index were calculated.

RESULTS

Dobutamine stress increased heart rate and cardiac output by 83% and 81%, respectively (both p < 0.0001), and mean transvalvular gradient increased from 15.6+/-5.5 mm Hg at rest to 35.4+/-11.9 mm Hg at maximum stress (p < 0.0001). Although the indexed effective orifice area was significantly lower in patients with a larger body surface area, this was not associated with any significant pressure gradient. The performance index of this valve was unchanged throughout the study. Regression analyses demonstrated that the mean transvalvular gradient at maximum stress was independent of all variables except resting gradient (p = 0.05). Body surface area had no association with the changes in cardiac output, transvalvular gradient at maximum stress, and effective orifice area.

CONCLUSIONS

These data show that the 21-mm Sorin Bicarbon bileaflet mechanical prosthesis offers an excellent hemodynamic performance with full utilization of its available orifice when implanted in the aortic position. The lack of significant transvalvular gradient in patients with a larger body surface area suggests that patient-prosthesis mismatch is highly unlikely when this prosthesis is used.

Prevention of spinal cord ischaemia during descending thoracic and thoracoabdominal aortic surgery

Surgery of the descending and thoracoabdominal aorta has been associated with post-operative paraparesis or paraplegia. Different strategies, which can be operative or non-operative, have been developed to minimise the incidence of neurological complications after aortic surgery. This review serves to summarise the current practice of spinal cord protection during surgery of the descending thoracoabdominal aortic surgery. The pathophysiology of spinal cord ischaemia will also be explained. The incidence of spinal cord ischaemia and subsequent neurological complications was associated with (1) the duration and severity of ischaemia, (2) failure to establish spinal cord supply and (3) reperfusion injury. The blood supply of the spinal cord has been extensively studied and the significance of the artery of Adamkiewicz (ASA) being recognised. This helps us to understand the pathophysiology of spinal cord ischaemia during descending and thoracoabdominal aortic operation. Techniques of monitoring of spinal cord function using evoked potential have been developed. Preoperative identification of ASA facilitates the identification of critical intercostal vessels for reimplantation, resulting in re-establishment of spinal cord blood flow. Different surgical techniques have been developed to reduce the duration of ischaemia and this includes the latest transluminal techniques. Severity of ischaemia can be minimised by the use of CSF drainage, hypothermia, partial bypass and the use of adjunctive pharmacological therapy. Reperfusion injury can be reduced with the use of anti-oxidant therapy. The aetiology of neurological complications after descending and thoracoabdominal aortic surgery has been well described and attempts have been made to minimise this incidence based on our knowledge of the pathophysiology of spinal cord ischaemia. However, our understanding of the development and prevention of these complications require further investigation in the clinical setting before surgery on descending and thoracoabdominal aorta to be performed with negligible occurrence of these disabling neurological problems.

Patient-prosthesis mismatch is negligible with modern small-size aortic valve prostheses

BACKGROUND

Concern has been raised about residual significant gradients when small aortic prostheses are used, particularly in patients with large body surface areas. We studied the performance of six types of small aortic prostheses using dobutamine stress echocardiography.

METHODS

Sixty-three patients (mean age, 67 +/- 7 years) who had undergone aortic valve replacement 17 +/- 6 months previously were studied. Two bileaflet mechanical prostheses (St. Jude Medical and CarboMedics: sizes, 19 mm and 21 mm) and two biological prostheses (Medtronic Intact and St. Jude BioImplant: size, 21 mm) were evaluated. A graded infusion of dobutamine was given and Doppler studies of valve performance were carried out.

RESULTS

All prostheses except one biological valve had acceptable hemodynamic performance under stress. Using regression modeling, gradient at rest was the only variable found to predict gradient under stress (p < 0.001). Moreover, the most important predictor of gradient at rest was valve design, which accounted for 72% of the variance (p < 0.001). This relationship was independent of valve size (19 mm or 21 mm) or material (ie, mechanical or biological). Body surface area accounted for 4% of the variance in gradient only.

CONCLUSIONS

The main predictor of transprosthetic gradient is the inherent characteristics of each particular prosthesis, with relatively insignificant contribution from variations in body surface area. Patient-prosthesis mismatch is not a problem of clinical significance when certain modern valve prostheses are used.

The effects of cardiopulmonary bypass temperature on inflammatory response following cardiopulmonary bypass

OBJECTIVES

The inflammatory response to cardiopulmonary bypass is believed to play an important role in end organ dysfunction after open heart surgery and may be more profound after normothermic systemic perfusion. The aim of the present study was to investigate the effects of cardiopulmonary bypass temperature on the production of markers of inflammatory activity after coronary artery surgery.

METHODS

Forty-five low risk patients undergoing elective coronary artery surgery were prospectively randomized into three groups: hypothermia (28 degrees C, n = 15), moderate hypothermia (32 degrees C, n = 15), and normothermia (37 degrees C, n = 15). All patients received cold antegrade crystalloid cardioplegia and topical myocardial cooling with saline at 4 degrees C. Serum samples were collected for the estimation of neutrophil elastase, interleukin 8, C3d, and IgG under ice preoperatively, 5 min after heparinisation, 30 min following start of CPB, at the end of CPB, 5 min after protamine administration, and 4, 12 and 24 h postoperatively.

RESULTS

Patients were similar with regard to preoperative and intraoperative characteristics (age, sex, severity of symptoms, number of grafts performed, aortic cross clamp time, cardiopulmonary bypass time). Neutrophil elastase concentration increased markedly as early as 30 min after the onset of cardiopulmonary bypass and peaked 5 min after protamine administration. Levels were not significantly different between the three groups. A similar finding was apparent for C3d release. Interleukin 8 concentrations also demonstrated a considerable increase related to cardiopulmonary bypass in all groups, but there was a significantly more rapid decline in interleukin 8 concentrations in the normothermic group in the postoperative period. Eluted IgG fraction showed a much earlier peak concentration than the other markers, occurring within 30 min of the start of cardiopulmonary bypass. Levels reached a plateau, before declining soon after the end of bypass and remained higher than preoperative values at 24 h. There was no difference between the three groups. The cumulative release of all markers was calculated from the concentration-time curves, and was not statistically different between groups.

CONCLUSION

Normothermic systemic perfusion was not shown to produce a more profound inflammatory response compared to hypothermic and moderately hypothermic cardiopulmonary bypass.

Intraoperative localisation and management of coronary artery fistula using transesophageal echocardiography

Coronary artery fistula is a rare congenital malformation that can be complicated by intracardiac shunts, endocarditis, myocardial infarction, coronary aneurysm and sudden death. Clinical symptomatology depends upon the underlying anatomy and the size of the fistulous connection between the left or right side of the heart. We report the successful management of a giant right coronary artery with fistulization into the right atrium. Intraoperative transesophageal echocardiography with colour flow Doppler was used for precise location of the fistulous communication, selective demonstration of vessels feeding the fistula and documentation of abolition of fistulous flow all without the need for cardiopulmonary bypass. Furthermore the effect of shunt occlusion on regional wall motion was documented which facilitated the successful ligation of the fistula.

Beating versus arrested heart revascularization: evaluation of myocardial function in a prospective randomized study

OBJECTIVE

Conventional coronary artery bypass grafting (CABG) is both safe and effective. Nevertheless, the use of cardiopulmonary bypass (CPB) and cardioplegic arrest are associated with several adverse effects. Over the last 2 years there has been a revival of interest in performing CABG on the beating heart. In this prospective randomized study we evaluated the efficacy and safety of on and off pump coronary revascularization on myocardial function.

METHODS

Eighty patients (65 males, mean age 61+/-9.7 years) undergoing first time CABG were prospectively randomized to: (i) conventional revascularization with CPB at normothermia and cardioplegic arrest with intermittent warm blood cardioplegia (on pump) or (ii) beating heart revascularization (off pump). Troponin I (Tn I) release was serially measured as a specific marker of myocardial damage. Haemodynamic measurements as well as inotropic requirement, incidence of arrhythmia and postoperative myocardial infarction were also recorded.

RESULTS

There were no significant differences between the two groups in terms of age, sex, extent of disease, left ventricular function and number of grafts. There were no deaths or intraoperative myocardial infarctions in either group. Tn I release was constantly lower in the off pump group and this was significant at 1, 4, 12 and 24 h postoperatively. Furthermore, in this group there was a significantly reduced incidence of arrhythmias. Inotropic requirements were less in the off pump group but this did not reach statistical significance.

CONCLUSION

These results suggest that off pump coronary revascularization is a safe and effective strategy for myocardial revascularization. Myocardial injury as assessed by Tn I release is also reduced when compared with conventional coronary revascularization with CPB and cardioplegic arrest.

Influence of normothermic systemic perfusion temperature on cold myocardial protection during coronary artery bypass surgery

OBJECTIVE

To determine the effect of normothermic systemic perfusion on myocardial injury when using cold cardioplegic techniques in patients undergoing coronary artery bypass surgery.

METHOD

Sixty six patients with stable angina pectoris were prospectively randomized into three groups according to cardiopulmonary bypass temperature: hypothermia (28 degrees C, n = 22), moderate hypothermia (32 degrees C, n = 22) and normothermia (37 degrees C, n = 22). All patients received cold antegrade crystalloid cardioplegia and topical cooling with saline at 4 degrees C. Serum samples were collected for troponin T and I estimation preoperatively, 4 hours after removal of the aortic cross clamp, and 12, 24, 36 and 48 hours postoperatively. In addition, serial electrocardiographic studies were undertaken on days 1, 3 and 5.

RESULTS

Patients were similar with regard to preoperative and intraoperative characteristics Four patients showed ECG changes typical of perioperative myocardial infarction but remained clinically well (28 degrees C, one; 32 degrees C, one; 37 degrees C, two). In the remaining 62 patients, serum troponin T increased significantly from a mean baseline value of 0.02 ng/ml to 1.5+/-0.9 ng/ml 4 hours after removal of the aortic cross-clamp (P<0.0001). Similarly, troponin I increased from 0.06 ng/ml to 0.63+/-0.47 ng/ml 12 hours after reperfusion (P<0.0001). Serum concentrations of both markers subsequently declined with time but remained higher than preoperative values at 48 hours. There were no differences between the three groups with respect to peak and cumulative serum troponin release. Normothermic cardiopulmonary bypass did not compromise the efficacy of cold myocardial protection when assessed by serum troponin concentrations in low risk patients undergoing coronary revascularization.

Warm blood cardioplegia reduces the fall in the intracellular concentration of taurine in the ischaemic/reperfused heart of patients undergoing aortic valve surgery

The effect of cold and warm intermittent antegrade blood cardioplegia, on the intracellular concentration of taurine in the ischaemic/reperfused heart of patients undergoing aortic valve surgery, was investigated. Intracellular taurine was measured in ventricular biopsies taken before institution of cardiopulmonary bypass, at the end of 30 min of ischaemic arrest and 20 min after reperfusion. There was no significant change in the intracellular concentration of taurine in ventricular biopsies taken after the period of myocardial ischaemia in the two groups of patients (from 10.1 +/- 1.0 to 9.6 +/- 0.9 mumol/g wet weight for cold and from 9.3 +/- 1.3 to 10.0 +/- 1.3 mumol/g wet weight for warm cardioplegia, respectively). Upon reperfusion however, there was a fall in taurine in both groups but was only significant (P < 0.05) in the group receiving cold blood cardioplegia (6.9 +/- 0.8 mumol/g wet weight after cold blood cardioplegia versus 8.0 +/- 0.8 mumol/g wet weight following warm blood cardioplegia). Like taurine, there were no significant changes in the intracellular concentration of ATP after ischaemia in the two groups of patients (from 3.2 +/- 0.32 to 2.95 +/- 0.43 mumol/g wet weight for cold and from 2.75 +/- 0.17 to 2.62 +/- 0.21 mumol/g wet weight for warm cardioplegia, respectively). However upon reperfusion there was a significant fall in ATP in both groups with the extent of the fall being less in the group receiving warm cardioplegia (1.79 +/- 0.19 mumol/g wet weight for cold and 1.98 +/- 0.27 mumol/g wet weight for warm cardioplegia, respectively). This work shows that reperfusion following ischaemic arrest with warm cardioplegia reduces the fall in tissue taurine seen after arrest with cold cardioplegia. Accumulation of intracellular sodium provoked by hypothermia and a fall in ATP, may be responsible for the fall in taurine by way of activating the sodium/taurine symport to efflux taurine.

Intermittent antegrade hyperkalaemic warm blood cardioplegia supplemented with magnesium prevents myocardial substrate derangement in patients undergoing coronary artery bypass surgery

OBJECTIVE

The influence of the addition of magnesium on myocardial protection with intermittent antegrade warm blood hyperkalaemic cardioplegia in patients undergoing coronary artery surgery was investigated and compared with intermittent antegrade warm blood hyperkalaemic cardioplegia only.

METHODS

Twenty-three patients undergoing primary elective coronary revascularization were randomized to one of two different techniques of myocardial protection. In the first group, myocardial protection was induced using intermittent antegrade warm blood hyperkalaemic cardioplegia. In the second group, the same technique was used except that magnesium was added to the cardioplegia. Intracellular substrates (ATP, lactate and amino acids) were measured in left ventricular biopsies collected 5 min after institution of cardiopulmonary bypass, after 30 min of ischaemic arrest and 20 min after reperfusion.

RESULTS

There were no significant changes in the intracellular concentration of ATP or free amino acid pool in biopsies taken at the end of the period of myocardial ischaemia. However, the addition of magnesium prevented the significant increase in the intracellular concentration of lactate seen with intermittent antegrade warm blood hyperkalaemic cardioplegia. Upon reperfusion there was a significant fall in ATP and amino acid concentration when the technique of intermittent antegrade warm blood hyperkalaemic cardioplegia was used but not when magnesium was added to the cardioplegia.

CONCLUSIONS

This work shows that intermittent antegrade warm blood hyperkalaemic cardioplegia supplemented with magnesium prevents substrate derangement early after reperfusion.

The end of the cold era: from intermittent cold to intermittent warm blood cardioplegia

BACKGROUND

A major reduction in the energy demand of the myocardium results from the electromechanical arrest, and cooling contributes to a lesser degree to this reduction. It is from this assumption that strategies of myocardial protection, utilizing warm blood cardioplegic induction, followed by cold cardioplegia with terminal warm reperfusion before removal of the aortic cross clamp, became established as optimal myocardial protection. Continuous normothermic perfusion 'closed the loop' by avoiding myocardial ischemia and linking warm induction and terminal reperfusion. A series of laboratory and clinical data confirmed the benefits of warm heart surgery on myocardial function and metabolism. The disadvantages of continuous warm blood cardioplegia including disturbance of the operative field, led surgeons to administer warm hyperkalaemic blood intermittently as a new cardioplegic strategy.

METHODS

This review examines the laboratory and clinical data with reference to the intermittent warm blood cardioplegia, to establish its experimental basis and place in clinical practice.

CONCLUSIONS

Experimental observation and clinical application have established intermittent warm blood cardioplegia as a practical, effective and cheap myocardial protection technique, particularly with reference to coronary artery surgery.

Metabolic differences between hearts of patients with aortic valve disease and hearts of patients with ischaemic disease

The hypertrophic hearts of patients with aortic valve disease are likely to have metabolic demands different from hearts with ischaemic disease. In this study we measured the myocardial concentration of ATP, ADP, lactate and 16 different amino acids in left ventricular biopsies collected from patients with aortic valve disease and from patients with ischaemic heart disease. Compared to hearts with ischaemic disease, hypertrophic hearts had significantly higher concentrations of ATP, but lower concentrations of lactate, branched-chain amino acids and alanine. These differences have important implications for energy metabolism and protein turnover in the two pathologies.

Endothelin-1 and endothelin receptors in porcine saphenous vein-carotid artery grafts

The regional distribution of endothelin-1 (ET-1) and its receptor subtypes (ETA and ETB) in porcine saphenous vein into carotid artery interposition grafts was studied 1 month after surgery and compared to ungrafted saphenous vein and carotid artery. ET-1 immunoreactivity was identified by immunohistochemistry and ET receptor subtypes were studied using in vitro autoradiography. In vein grafts, there was a higher density of ETA compared to ETB receptor binding in both the tunica media and the neointima. ETA binding to the tunica media of ungrafted saphenous vein was greater than that in the carotid artery or vein grafts, but greater in the vein graft compared to the carotid artery. Immunoreactive ET-1 was located in endothelial cells and throughout the neointima of the vein graft. Dense ETA and ETB binding was also associated with adventitial microvessels in the graft, and ETB binding was also identified to neutrophils, which accumulated at the subendothelium and within the adventitia. ETA receptors may play a role in vein graft thickening at the medial and neointimal vascular smooth-muscle cell level, whereas ETB receptors may play a role in microangiogenesis. The high levels of ETA receptors in the tunica media of ungrafted saphenous vein, relative to the carotid artery and vein graft, may also render this conduit susceptible to neointimal formation. These data indicate that studies of the effect of ET receptor antagonists on the pathobiology of vein graft disease are warranted.

Warm blood hyperkalaemic reperfusion ('hot shot') prevents myocardial substrate derangement in patients undergoing coronary artery bypass surgery

OBJECTIVE

A significant metabolic derangement occurs in the ischaemic-reperfused heart of patients undergoing coronary artery bypass surgery using cold blood cardioplegia. The aim of the present study was to investigate whether this effect could be reversed by complementing cold blood cardioplegia with a short terminal exposure of warm blood hyperkalaemic cardioplegia ('hot shot').

METHODS

Thirty-five patients undergoing primary elective coronary revascularisation were randomized to one of two different techniques of myocardial protection. In the cold blood group (n = 17) myocardial protection was induced using antegrade hyperkalaemic cold blood cardioplegic solution. In the hot shot group (n = 18) this was supplemented with a short exposure to hyperkalaemic warm blood cardioplegia prior to removal of the cross clamp. Intracellular substrates (ATP and amino acids) were measured in left ventricular biopsies collected 5 min after institution of cardiopulmonary bypass, after 30 min of ischaemic arrest and 20 min after reperfusion.

RESULTS

Biopsies taken at the end of the period of myocardial ischaemia, when compared to control, did not show any significant change in the intracellular concentration of ATP (from 2.71 +/- 0.32 to 2.43 +/- 0.37 micromol g wet for cold blood group and from 2.6 +/- 0.3 to 2.5 +/- 0.34 micromol/g wet weight for hot shot group) or total free intracellular amino acids pool (from 33.0 +/- 1.4 to 30.0 +/- 1.4 micromol/g wet weight for cold blood group and from 34.0 +/- 1.4 to 34.5 +/- 2.3 micromol/g wet weight for hot shot group). Upon reperfusion, however, there was a significant fall in ATP (23.7 +/- 1.6 micromol/g wet weight amino acids, P < 0.05) and in amino acids (1.53 +/- 0.24 micromol/g wet weight, P < 0.05) in the group receiving only cold blood cardioplegia but not in the hot shot group (2.27 +/- 0.27 micromol/g wet weight ATP and 30.5 +/- 1.6 micromol/g wet weight amino acids).

CONCLUSIONS

The data suggest that warm blood hyperkalaemic reperfusion hot shot prevents myocardial metabolic derangement seen during coronary artery surgery.

Distribution of endothelin-1 (ET) receptors (ET(A) and ET(B)) and immunoreactive ET-1 in porcine saphenous vein-carotid artery interposition grafts

Proliferation of vascular smooth muscle cells (VSMC) is a principal event in neointima formation in saphenous vein-coronary artery bypass grafts. Since endothelin-1 (ET-1) promotes VSMC replication and ET-1 receptor antagonists inhibit neointima formation in arterial injury models, it is reasonable to propose that ET-1 may be involved in neointima formation in vein grafts. However, it is not known what alterations of ET-1 and its receptors (if any) occur in vein grafts. The objective of this study, therefore, was to investigate the distribution of ET-1 and ET-1 receptor subtypes (ET(A) and ET(B)) in porcine vein grafts. Unilateral interposition saphenous vein grafting was performed by end to end anastomosis after excision of a segment of carotid artery in Landrace pigs. One month after surgery, vein grafts, ungrafted saphenous veins and carotid arteries were excised, ET-1 immunoreactivity identified by immunocytochemistry and ET(A) and ET(B) receptor subtypes studied using autoradiography. In vein grafts, there was a greater density of ET(A) compared to ET(B) receptors in both the tunica media and neointima. ET(A) binding in the tunica media of ungrafted saphenous vein was greater than that in the carotid artery or vein grafts, but greater in the vein graft compared to the carotid artery. Immunoreactive ET-1 was located in endothelial cells and throughout the neointima of the vein graft. Dense ET-1 binding (to both ET(A) and ET(B) receptors) was also associated with microvessels in the adventitia within the graft. In vein grafts, there was strong ET(B) binding to neutrophils which were present in high numbers at the subendothelium and within the adventitia. It is concluded ET(A) receptors may play a role in vein graft thickening at the medial and neointimal VSMC level, whereas ET(B) receptors may play a role in microangiogenesis. The higher levels of ET(A) receptors in the tunica media of ungrafted saphenous vein relative to the carotid artery and vein graft may also render this conduit susceptible to neointima formation. These data indicate that studies on the effect of ET receptor antagonists on the pathobiology of vein graft disease is warranted.

External stenting reduces long-term medial and neointimal thickening and platelet derived growth factor expression in a pig model of arteriovenous bypass grafting

Bypass of stenotic coronary arteries with autologous saphenous vein is an established treatment for ischemic heart disease. However, its long-term clinical success is limited. Late vein graft failure is the result of medial and intimal thickening consequent upon medial vascular smooth muscle cell migration, proliferation and extracellular matrix deposition, followed later by superimposed atherosclerosis. These changes directly compromise graft blood flow and provoke thrombosis. Vein graft wall thickening may represent an adaptation imposed by arterial hemodynamic factors, and these factors have been shown to promote vascular smooth muscle cell migration and proliferation through activation of key mediators including platelet-derived growth factor (PDGF). Many pharmacological interventions aimed at preventing these long-term changes have proven unsuccessful in clinical evaluation. We recently demonstrated in a pig saphenous vein graft model that application of an external polyester stent to the outside of carotid interposition vein grafts reduced intimal hyperplasia and total wall thickness 1 month after implantation. However, it is not known whether the benefits of the stent are maintained in the longer term or what mechanisms underlie its effect. The present study therefore compared morphological changes and PDGF expression in stented grafts and contralateral unstented grafts in the same pigs, 6 months after graft implantation. Reduced medial thickening, neointima formation, and cell proliferation were sustained in externally stented grafts, and these effects were associated with a significant reduction in PDGF expression.

Staged minimally invasive direct coronary artery bypass and percutaneous angioplasty for multivessel coronary artery disease

OBJECTIVE

Minimally invasive direct coronary artery bypass (MIDCAB) using the left internal mammary artery (IMA) to the left anterior descending (LAD) coronary artery can be performed with low operative risk. MIDCAB can be combined with percutaneous transluminal coronary angioplasty (PTCA) to treat patients with multivessel disease. We report here our experience with staged MIDCAB and PTCA in the management of a selected group of patients.

METHODS AND RESULTS

11 patients (9 males, mean age 64.6+/-8.7 years) with multivessel coronary artery disease received left IMA grafts to the LAD using the MIDCAB approach. There were no postoperative morbidity or mortality. All patients were extubated within 4 h of leaving the operating room with a mean ITU stay of 12.8 h. All patients but two underwent coronary angioplasty during the same hospital admission, 3.8+/-1.3 days after the MIDCAB procedure. Angiography confirmed IMA grafts patency in all patients, and complete revascularisation by PTCA of other coronary arteries was possible in all patients but one. Mean hospital stay was 5.9 days, and all patients remain free of angina at a mean follow-up period of 11.4 months.

CONCLUSIONS

Staged MIDCAB and angioplasty is an experimental approach for the management of selected patients with multi-vessel coronary artery disease. Further experience is needed to clarify patient selection and the long-term outcome of this approach.

Left ventricular volume reduction surgery

Left ventricular volume reduction has recently been introduced as a surgical treatment for end stage dilated cardiomyopathy. This operation involves the resection of a slice of viable left ventricular myocardium in order to reduce the wall tension imposed upon the contracting heart chamber. Early results are encouraging, but clinical evaluation on a larger scale is required. In the present article, we describe the indications, surgical principles and results of left ventricular volume reduction surgery with reference to our group's experience.

Towards the prevention of vein graft failure

Improved outcome after coronary bypass surgery over the last decade has been attributed largely to the increasing use of arterial conduits and their superior patency rates over that of saphenous vein grafts. In spite of this trend, autologous saphenous vein has remained an important and convenient conduit for a variety of operative scenarios, and is still used for more than 70% of grafts. As a result, vein graft failure continues to represent a significant clinical and economic burden upon the health care service. Between 15 to 30% of saphenous vein grafts occlude within the first year of surgery, increasing to over 50% after 10 years. By this time, more than 10% of patients will require further intervention to alleviate symptoms arising from occluded grafts and progression of native disease. Graft occlusion arises either from early thrombosis or the later onset of 'vein graft disease' and subsequent atherosclerotic changes.

Influence of normothermic systemic perfusion during coronary artery bypass operations: a randomized prospective study

OBJECTIVES

Normothermic cardiopulmonary bypass has been proposed as a more physiologic technique than hypothermic bypass for the maintenance of the body during cardiac surgery. The aims of this study were to investigate the effects of systemic perfusion temperature on clinical outcome after coronary revascularization.

METHODS

Three hundred patients (mean age 60 +/- 9 years, 88% male) were prospectively randomized into three groups: hypothermia (28 degrees C, n = 100), moderate hypothermia (32 degrees C, n = 100), and normothermia (37 degrees C, n = 100). All patients received cold antegrade St. Thomas' Hospital crystalloid cardioplegic solution, and patients in the normothermic group were actively rewarmed during cardiopulmonary bypass (nasopharyngeal temperature 37 degrees C).

RESULTS

No differences were found between groups with respect to mortality (1%), intraaortic balloon pump use, perioperative infarction rates, focal neurologic deficits (1%), intubation time, intensive care unit stay, and postoperative hospital stay. Further stepwise regression analysis identified age and intensive care unit stay as important predictors of the variability in postoperative stay (both R2 = 0.114; p < 0.001), whereas perfusion temperature remained a nonsignificant explanator. Normothermic perfusion necessitated larger doses of phenylephrine to maintain arterial pressure above 50 mm Hg during cardiopulmonary bypass (p < 0.0001 vs 28 degrees C, p < 0.01 vs 32 degrees C) but less requirement for electrical defibrillation during reperfusion (p < 0.05 vs 32 degrees C, p < 0.01 vs 28 degrees C). Total chest drainage was not different between groups, but patients undergoing normothermic cardiopulmonary bypass required less transfusion of blood (p < 0.05 vs 28 degrees C and 32 degrees C) and platelets (p < 0.04 vs 32 degrees C, p < 0.001 vs 28 degrees C) in the postoperative period.

CONCLUSIONS

Cardiopulmonary bypass temperature did not influence early clinical outcome after routine coronary artery bypass operations. Normothermic systemic perfusion was associated with an increased requirement for vasoconstrictors and reduced requirements for electrical defibrillation and transfusion of blood products.