Administration of Octreotide for Management of Postoperative High-Flow Chylothorax

Chylothorax is a rare complication of adult cardiothoracic surgery that can affect the postoperative course as it can lead to respiratory insufficiency, protein loss, fluid imbalance, and immunodeficiency. We report the case of a 51-year-old man who developed a persistent high-flow chylothorax after replacement of the descending thoracic aorta for an aneurysm. After a week of complete oral intake cessation and total parenteral nutrition, we started administration of octreotide, a somatostatin analog. It led to rapid cessation of chyle production, and the patient was discharged without further complications and chylothorax relapses.

Adult-age donors offer acceptable long-term survival to pediatric heart transplant recipients: an analysis of the United Network of Organ Sharing database

OBJECTIVES

A critical shortage of donor organs has caused many centers to use less restrictive donor criteria, including the use of adult-age donors for pediatric recipients. The purpose of this study is (1) to describe the supply of pediatric (0-18 years) heart donors, (2) to explore the relationship between donor age and long-term survival, and (3) to define threshold age ranges associated with decreased long-term survival.

METHODS

The United Network of Organ Sharing provided deidentified patient-level data. Primary analysis focused on 1887 heart transplant recipients aged 9 to 18 years undergoing transplantation from October 1, 1987, to September 25, 2005. Kaplan-Meier analysis and log-rank tests were used in time-to-event analysis. Receiver operating characteristic curves and stratum-specific likelihood ratios were generated to compare survival at various donor age thresholds.

RESULTS

The number of pediatric donors decreased (P < .001) over the study period, particularly from 1993 (n = 640) through 2004 (n = 432). Among recipients aged 9 to 18 years, univariate analysis demonstrated a statistically significant (P < .001) inverse relationship between donor age and survival. Stratum-specific likelihood ratio analysis generated 3 strata for donor age: the low-risk, intermediate-risk, and high-risk groups consisted of donors aged 13 years or younger (n = 611, 32.41%), 14 to 51 years (n = 1258, 66.7%), and 52 years and older (n = 16, 0.85%), respectively. In the low-risk, intermediate-risk, and high-risk groups median survival was 4069 days (11.1 years), 3495 days (9.57 years), and 1197 days (3.28 years), respectively.

CONCLUSIONS

Although donors aged 13 years or less offer pediatric recipients the best chance for achieving long-term survival, donors aged 14 to 51 years offer good outcomes to pediatric recipients. Consideration should be given to expanded use of well-selected adult-age donors for pediatric recipients.

Does A Pre-Left Ventricular Assist Device Screening Score Predict Long-Term Transplantation Success? A 2-Center Analysis

BACKGROUND

A risk factor summation score was previously validated to successfully predict survival after insertion of a left ventricular assist device (LVAD). We investigated whether this scoring system also predicts clinical outcomes after eventual heart transplantation in LVAD recipients.

METHODS

A retrospective review was performed on 153 consecutive patients who received an LVAD as a bridge to transplantation at 2 large-volume centers from 1996 to 2003. The scoring system was used to designate low- and high-scoring groups.

RESULTS

Thirty-day mortality and 5-year survival after transplantation were equivalent between groups (4.46% versus 7.32% and 76% versus 70%, respectively). No difference was seen in length of posttransplantation ventilator dependence (2.83 +/- 0.49 versus 3.3 +/- 0.72 days) or intensive care unit monitoring (6.38 +/- 0.77 versus 6.97 +/- 1.1 days). However, low-scoring patients had a significantly decreased duration of inotrope support (5.57 +/- 0.45 versus 7.74 +/- 1.0 days, P = .035).

CONCLUSION

A risk factor summation score may predict which LVAD patients will require prolonged inotropic support following heart transplantation. However, survival in high-risk (elevated score) LVAD patients following heart transplantation is comparable to low-risk groups, favoring the continued practice of LVAD implantation as a bridge to transplantation even in high-risk patients.

Reduction Ascending Aortoplasty: Midterm Follow-Up and Predictors of Redilatation

BACKGROUND

Reduction ascending aortoplasty is an alternative procedure to the replacement of the ascending aorta in case of ascending aorta aneurysm without aortic root involvement. This study was designed to evaluate the midterm follow-up of aortoplasty and to determine predictors of redilatation.

METHODS

From January 1, 1998, to April 30, 2005, 68 patients with dilatation of the ascending aorta underwent unsupported reduction aortoplasty in combination with other cardiac procedures. All patients underwent associated surgical procedures. Sixty patients (88.2%) underwent associated aortic valve replacement. Cumulative follow-up time was 191.4 patient-years and was 100% complete. Median follow-up time was 2.5 years, and mean follow-up time was 2.9 +/- 1.7 years (range, 0.4 to 6.3 years).

RESULTS

The overall perioperative mortality rate was 1.5%. Overall survival estimates at 3 and 6 years were 93.3% +/- 4.5% and 89.3% +/- 5.9%, respectively. The actuarial freedom from cardiac-related death at 3 and 6 years was 100% and 95.7% +/- 4.3%, respectively. Ascending aorta redilatation occurred in 5 patients (7.5%). The actuarial freedom from redilatation at 3 and 6 years was 97.7% +/- 2.3% and 79.8% +/- 8.4%, respectively. The actuarial freedom from reoperation at 3 and 6 years was 100% and 86.3% +/- 7.5%, respectively. Only preoperative diameter was a significant predictor of redilatation using multivariate stepwise logistic regression analysis.

CONCLUSIONS

Unsupported reduction aortoplasty is a safe and effective technique with low mortality, low morbidity, and rare late complications for selected chronic aneurysm of the ascending aorta with diameter less than 55 mm.

Effect of Cryopreservation Techniques on Aortic Valve Glycosaminoglycans

This study was designed to evaluate the effect of cryopreservation on the glycosaminoglycan (GAG) content of the aortic allografts. Twenty-one porcine aortic valves were obtained. Five aortic roots were immediately analyzed without cryopreservation, eight were cryopreserved in closed leaflet position, and eight in open leaflet position. The groups were compared in terms of GAG concentration and subclass proportion in three different zones including the aortic root wall, the commissures, and the leaflets. GAG content at the commissures was significantly lower in the closed leaflet group than in the other groups (P = 0.001). The electrophoretic analysis did not show any significant difference in the zonal distribution of GAG classes between groups. Quantitative analysis in various aortic valve zones suggests that cryopreservation can alter the GAG content. Cryopreservation of the aortic valve in an open leaflet position can preserve the matrix more efficiently and might prolong the durability of the aortic allograft.

Predictors and Outcomes of Continuous Veno-venous Hemodialysis Use After Implantation of a Left Ventricular Assist Device

BACKGROUND

Post-operative renal failure is a common complication after left ventricular assist device (LVAD) implantation. This study was designed to evaluate predictors and outcomes of acute renal failure after LVAD insertion.

METHODS

Two-hundred one patients undergoing LVAD implantation at a single institution from June 1996 through April 2004 were retrospectively analyzed. Patients were categorized into 2 groups: those who required post-operative continuous veno-venous hemodialysis (CVVHD) (Group 1, n = 65, 32.3%) and those who did not (Group 2, n = 136, 67.7%). Independent predictors of post-operative renal failure requiring CVVHD were determined using multivariate logistic regression techniques.

RESULTS

Patients who had post-operative renal failure requiring CVVHD were older (53.7 +/- 12.9 vs 48.2 +/- 14.2 years, p = 0.009), had a higher incidence of intra-aortic balloon pump use (46.6% vs 26.2%, p = 0.006), and had a higher pre-operative mean LVAD score (5.8 +/- 3.5 vs 3.8 +/- 3.3, p = 0.001) than those without renal failure. LVAD score was the only independent predictor of post-operative renal failure requiring CVVHD (odds ratio = 1.226, p = 0.006). Sepsis rate was higher (33.3% vs 6.9%, p < 0.001) and bridge-to-transplantation rate was lower (52.4% vs 83.5%, p < 0.001) in Group 1 than in Group 2. Post-LVAD survival rates at 1, 3, 5 and 7 years for Group 1 and Group 2 were 43.2%, 39.1%, 34.7% and 34.7% vs 79.2%, 74.0%, 68.3% and 66.4%, respectively (log rank, p < 0.001).

CONCLUSIONS

Acute renal failure necessitating CVVHD remains a serious complication after LVAD and confers significant morbidity and mortality. Pre-operative evaluation of patient risk factors and optimization of peri-operative hemodynamics are of utmost importance to prevent this major complication.

Effect of Donor Age on Long-Term Survival Following Cardiac Transplantation

BACKGROUND AND AIM

The current shortage of donor hearts has forced the criteria of organ procurement to be extended, leading to increased use of older donor hearts to bridge the gap between demand and availability. Our objective was to analyze the effect of donor age on outcomes after cardiac transplantation.

METHODS

We retrospectively studied 864 patients who underwent cardiac transplantation at New York Presbyterian Hospital - Columbia University between 1992 and 2002. Patients were divided into two groups; donor age <40 years (Group A, n = 600) and donor age > or =40 years (Group B, n = 264).

RESULTS

Characteristics including gender, body mass index, and cytomegalovirus (CMV) status were significantly different between the two donor age groups. Race, CMV status, toxoplasmosis status, left ventricular assist device prior to transplant, diabetes mellitus, and retransplantation were similar in both the recipient groups, while age, gender, and BMI were different. Early mortality was lower in Group A, 5%, versus 9.5% in Group B. Multivariate analysis revealed recipient female gender (odd ratio (OR) = 1.71), retransplantation (OR = 1.63), and increased donor age (OR = 1.02) as significant predictors of poor survival in the recipient population. Actuarial survival at 1 year (86.7% vs 81%), 5 years (75% vs 65%), and 10 years (56% vs 42%) was significantly different as well with a log rank p = 0.002.

CONCLUSIONS

These findings suggest that increased donor age is an independent predictor of long-term survival. However, the shortage of organs makes it difficult to follow strict guidelines when placing hearts; therefore, decisions need to be made on a relative basis.

Coronary artery bypass grafting in patients with low ejection fraction

BACKGROUND

Patients with low ejection fraction (EF) are at a higher risk for postoperative complications and mortality. Our objective was to assess the effect of low EF on clinical outcomes after coronary artery bypass grafting (CABG).

METHODS AND RESULTS

We analyzed 55,515 patients from New York State database who underwent CABG between 1997 and 1999. Patients were stratified into 1 of the 4 EF groups: Group I (EF< or =20%), Group II (EF 21% to 30%), Group III (EF 31% to 40%), and Group IV (EF>40%). History of previous myocardial infarction, renal failure, and congestive heart failure were higher in patients with low EF (all P<0.001). Group I experienced a higher incidence of postoperative respiratory failure (10.1% versus 2.9%), renal failure (2.5% versus 0.6%), and sepsis (2.5% versus 0.6%) compared with Group IV. In-hospital mortality was significantly higher in Group I (6.5% versus 1.4%; P<0.001). Multivariate analysis showed hepatic failure [odds ratio (OR), 11.2], renal failure (OR, 4.1), previous myocardial infarction (OR, 3.4), reoperation (OR, 3.4), emergent procedures (OR, 3.2), female gender (OR, 1.7), congestive heart failure (OR, 1.6), and age (OR, 1.04) as independent predictors of in-hospital mortality in the low EF group. The discharges to home rate were significantly lower in Group I versus Group IV (73.1% and 87.7%, respectively; P<0.001).

CONCLUSIONS

Patients with low EF are sicker at baseline and have >4 times higher mortality than patients with high EF. However, outcomes are improving over time and are superior to historical data. Therefore, CABG remains a viable option in selected patients with low EF.

Resveratrol, a natural red wine polyphenol, reduces ischemia-reperfusion-induced spinal cord injury

BACKGROUND

Severe neurologic injury still represents one of the most devastating complications after surgical repair of thoracoabdominal aneurysms. We therefore aimed to investigate the protective effect of resveratrol, a natural polyphenol antioxidant present in grapes and wine, in an experimental model of spinal cord ischemia-reperfusion injury.

METHODS

Sixteen rabbits were assigned either to group A (n = 8; receiving resveratrol, treated group) or group B (n = 8; control group, nontreated group) and underwent a 30-minutes period of spinal cord ischemia by clamping the abdominal aorta between the left renal artery and the aortic bifurcation. Fifteen minutes before clamping, rabbits received either intravenous resveratrol (100 microg/kg; group A) or normal saline (group B). Functional assessment with Tarlov score at 8, 16, and 24 hours postoperatively, histopathologic assessment of the spinal cord, measurements of malondialdehyde levels, and myeloperoxidase activity in the spinal cord were performed.

RESULTS

Neurologic impairment (Tavlov score for group A = 4.38 +/- 1.19 and for group B = 0.38 +/- 0.74, p < 0.001), malondialdehyde levels (47.71 +/- 7.81 nmol/g versus 86.56 +/- 11.39 nmol/g, p < 0.001), and myeloperoxidase activity (2.13 +/- 0.72 nm/min versus 3.75 +/- 0.78 nm/min, p = 0.002) were significantly lower in the resveratrol-treated animals. Additionally, pathologically assessed outcomes were better in the resveratrol-treated group. The total number of motor neurons in the gray matter was significantly lower in the nontreated group than in the resveratrol-treated group (14.26 +/- 2.94 versus 29.12 +/- 3.64, p = 0.003).

CONCLUSIONS

Prophylactic use of resveratrol reduced neurologic injury and provided clinical improvement by attenuating the inflammatory milieu in the rabbit spinal cord ischemia/reperfusion model.

Effect of Diabetes on Short- and Long-term Outcomes After Left Ventricular Assist Device Implantation

BACKGROUND

Diabetes mellitus (DM) is a frequent co-morbidity in patients with congestive heart failure (CHF). Implantation of LVADs is an acceptable option for diabetic patients with end-stage heart failure, yet no previous study has specifically examined the clinical outcomes of this patient population.

METHODS

A retrospective analysis was performed on all patients who underwent LVAD insertion at a single institution from June 17, 1996 to April 14, 2004. Patients were divided into 2 groups: diabetics (DM) and non-diabetics (NDM). The groups were compared with regard to demographics, etiology of heart failure, body mass index (BMI), intensive care unit (ICU) stay, early mortality (< or =30 days), bridge-to-transplantation rate and post-LVAD and post-transplant survival.

RESULTS

Two hundred one patients were identified. Of these, 49 (24.4%) had DM. Compared with the NDM group, DM patients had a higher mean body mass index (30.1 +/- 6.0 vs 26.1 +/- 4.8, p < 0.001) and a higher proportion of hypertension (57.4% vs 19.7%, p < 0.001). Although post-LVAD survival was similar, post-transplant survival in DM patients was significantly lower compared with NDM patients, with 1-, 3-, 5- and 7-year actuarial survival rates of 86.9%, 71.0%, 56.5% and 56.5% vs 90.5%, 88.4%, 83.0% and 80.7% (p = 0.020), respectively.

CONCLUSIONS

Carefully selected diabetic patients can be successfully bridged to transplantation using LVADs with comparable outcomes to non-diabetic patients. Reasons for diminished post-transplant survival in this cohort are unclear and necessitate the conductance of multi-institutional studies to evaluate outcomes.

Effects of Resveratrol in Storage Solution on Adhesion Molecule Expression and Nitric Oxide Synthesis in Vein Grafts

BACKGROUND

Endothelial injury in human saphenous vein grafts may occur during harvesting and storage, which may have an adverse effect on coronary artery bypass grafting outcome. In this study, we sought to determine whether resveratrol, a natural antioxidant enriched in grape, can limit endothelial activation and reduce endothelial injury in human saphenous vein grafts.

METHODS

Human saphenous vein grafts, obtained from 8 patients and divided into two equal groups of control and study specimens, were stored in either heparinized blood (group A) or heparinized blood containing 50 microg/mL resveratrol (group B) for 1 hour at room temperature. Specimens were analyzed by Western blotting to quantify intercellular adhesion molecule-1, vascular cell adhesion molecule-1, and inducible nitric oxide synthase-2 expression, as well as tissue cyclic guanylate monophosphate levels. Myeloperoxidase activity, a marker of neutrophil sequestration in human saphenous vein grafts, was also measured in each group.

RESULTS

Intercellular adhesion molecule-1 expression (1,674 +/- 332 versus 559 +/- 282; p = 0.003), vascular cell adhesion molecule-1 expression (753 +/- 183 versus 472 +/- 151; p = 0.025), and myeloperoxidase activity (7.00 +/- 1.05 versus 1.33 +/- 0.45 nm/min; p = 0.004) were significantly lower in group B. In contrast, inducible nitric oxide synthase-2 expression (548 +/- 237 versus 2,234 +/- 726; p = 0.004) and tissue cyclic guanylate monophosphate levels (2.02 +/- 0.53 versus 5.61 +/- 0.89 pmol/mL; p = 0.001) were significantly higher in group B.

CONCLUSIONS

Resveratrol reduced upregulation of leukocyte-endothelial cell adhesion molecule expression in human saphenous vein graft endothelium and decreased neutrophil adhesion to saphenous vein graft endothelium. Resveratrol also augmented inducible nitric oxide synthase-2 expression and increased cyclic guanylate monophosphate levels. These results suggest that resveratrol might improve vascular homeostasis and reduce endothelial injury during the hypoxic storage period of human saphenous vein grafts for coronary artery bypass grafting.

Adhesiolysis is Facilitated by Robotic Technology in Reoperative Cardiac Surgery

Over a 2-year period, 5 patients who required reoperative chest surgery underwent robotic adhesiolysis with the da Vinci (Intuitive, Sunnyvale, CA) system. Resternotomy was performed under direct visualization for coronary revascularization (n = 2) or valve replacement (n = 1). A fourth patient required coronary revascularization after a previous axilloaxillary bypass. The final case involved the preparation of a substernal pathway for a gastric pull-up. In all cases adhesions were taken down without injury to the underlying structures. All grafts were preserved, and all patients recovered uneventfully. Robotic adhesiolysis is a versatile technique that allows careful lysis of adhesions and minimizes the risk of major complication during reoperative chest surgery.

A decade experience of cardiac retransplantation in adult recipients

BACKGROUND

Cardiac retransplantation is considered to be the best therapeutic option for a failing cardiac allograft. However, poor outcomes with retransplantation have previously been reported, a factor that raises important ethical, logistic and financial issues given the limited organ donor supply.

METHODS

Seven hundred sixty-six adult patients underwent cardiac transplantation for end-stage heart failure at our institution from 1992 to 2002. Of these, 41 (5.4%) were retransplants. Variables examined included recipient and donor demographics, indications for retransplant, comorbidities, cytomegalovirus (CMV) serology status, left ventricular assist device use before transplant, donor ischemic time, rate of early mortality (within 30 days), and post-transplantation survival rate.

RESULTS

Indications for cardiac retransplant were transplant-related coronary artery disease in 37, acute rejection in 3, and other causes in 1. The mean interval between transplantation and retransplantation was 5.9 +/- 3.4 years. Baseline characteristics such as recipient age, gender, CMV serology status, and donor age were similar in the primary transplant and retransplant groups. Early mortality after transplantation was comparable between the 2 groups, but post-transplant survival was significantly lower in retransplant patients compared with primary transplants with 1-, 3-, 5-, and 7-year actuarial survival rates of 72.2%, 66.3%, 47.5%, and 40.7% vs. 85.1%, 79.2%, 72.9%, and 66.8%, respectively (p < 0.001).

CONCLUSIONS

Cardiac retransplantation offers short-term outcomes similar to primary transplantation but lower long-term survival rates. Non-retransplant surgical options should also be considered in these patients. Careful patient selection and risk-assessment is necessary to govern appropriate allocation of limited donor organs.

Endocytic delivery of lipocalin-siderophore-iron complex rescues the kidney from ischemia-reperfusion injury

Neutrophil gelatinase-associated lipocalin (Ngal), also known as siderocalin, forms a complex with iron-binding siderophores (Ngal:siderophore:Fe). This complex converts renal progenitors into epithelial tubules. In this study, we tested the hypothesis that Ngal:siderophore:Fe protects adult kidney epithelial cells or accelerates their recovery from damage. Using a mouse model of severe renal failure, ischemia-reperfusion injury, we show that a single dose of Ngal (10 microg), introduced during the initial phase of the disease, dramatically protects the kidney and mitigates azotemia. Ngal activity depends on delivery of the protein and its siderophore to the proximal tubule. Iron must also be delivered, since blockade of the siderophore with gallium inhibits the rescue from ischemia. The Ngal:siderophore:Fe complex upregulates heme oxygenase-1, a protective enzyme, preserves proximal tubule N-cadherin, and inhibits cell death. Because mouse urine contains an Ngal-dependent siderophore-like activity, endogenous Ngal might also play a protective role. Indeed, Ngal is highly accumulated in the human kidney cortical tubules and in the blood and urine after nephrotoxic and ischemic injury. We reveal what we believe to be a novel pathway of iron traffic that is activated in human and mouse renal diseases, and it provides a unique method for their treatment.

Endocytic delivery of lipocalin-siderophore-iron complex rescues the kidney from ischemia-reperfusion injury

Neutrophil gelatinase-associated lipocalin (Ngal), also known as siderocalin, forms a complex with iron-binding siderophores (Ngal:siderophore:Fe). This complex converts renal progenitors into epithelial tubules. In this study, we tested the hypothesis that Ngal:siderophore:Fe protects adult kidney epithelial cells or accelerates their recovery from damage. Using a mouse model of severe renal failure, ischemia-reperfusion injury, we show that a single dose of Ngal (10 microg), introduced during the initial phase of the disease, dramatically protects the kidney and mitigates azotemia. Ngal activity depends on delivery of the protein and its siderophore to the proximal tubule. Iron must also be delivered, since blockade of the siderophore with gallium inhibits the rescue from ischemia. The Ngal:siderophore:Fe complex upregulates heme oxygenase-1, a protective enzyme, preserves proximal tubule N-cadherin, and inhibits cell death. Because mouse urine contains an Ngal-dependent siderophore-like activity, endogenous Ngal might also play a protective role. Indeed, Ngal is highly accumulated in the human kidney cortical tubules and in the blood and urine after nephrotoxic and ischemic injury. We reveal what we believe to be a novel pathway of iron traffic that is activated in human and mouse renal diseases, and it provides a unique method for their treatment.

Advances in heart failure surgery

Heart failure is a major public health problem in the USA and in most Western countries. Nearly 5 million patients in the USA have heart failure with approximately 500,000 patients being diagnosed for the first time each year. Medical therapy is the first-line treatment, and surgery is considered when medical therapy fails or a clear mechanical cause of heart failure is identified and deemed correctable. Current surgical options include coronary revascularization, surgical correction of mitral regurgitation, left ventricular reconstruction, transmyocardial laser revascularization, ventricular assist devices, passive ventricular restraint devices, and cardiac transplantation. While a full discussion of cardiac transplantation is beyond the scope of this article, the other commonly performed procedures will be reviewed.

Acceptable recipient outcomes with the use of hearts from donors with hepatitis-B core antibodies

BACKGROUND

The shortage of available donors limits cardiac transplantation. Use of hearts from patients with hepatitis-B core antibodies could expand the donor pool but are usually avoided because of concern about virus transmission. We conducted a retrospective review to determine the safety of transplanting hearts from donors with hepatitis-B core antibodies.

METHODS

We reviewed donor and recipient charts for patients who underwent transplantation at our center between January 1, 1997, and December 1, 2002.

RESULTS

A total of 541 heart transplantations were performed in this time period. Thirty-three patients (aged 47.5 +/- 18.8 years) received hearts from core-antibody-positive donors (aged 37.7 +/- 10.8 years). Of these, 5 patients received prophylactic antibiotic treatment with lamivudine after transplantation. Only 1 patient (baseline surface-antigen-negative and without prophylaxis) experienced donor-transmitted hepatitis B infection 10 months after transplantation that was treated with lamivudine. Two patients (baseline surface-antibody-negative) had hepatitis B seroconversion, becoming surface-antibody positive without evidence of infection. None of the 5 patients who received prophylaxis with lamivudine had donor-transmitted hepatitis, and only 1 lamivudine-treated patient had surface antibodies. Post-transplant survival in this small cohort was similar to that for all patients who underwent transplantation at our center during this time period.

CONCLUSIONS

Transplantation of hearts from donors with hepatitis-B core antibodies is associated with a small viral-transmission risk, with or without post-transplant, anti-viral prophylaxis. Use of these donor hearts should be considered safe and may help to augment the available donor pool.

The renal papilla is a niche for adult kidney stem cells

Many adult organs contain stem cells, which are pluripotent and are involved in organ maintenance and repair after injury. In situ, these cells often have a low cycling rate and locate in specialized regions (niches). To detect such cells in the kidney, we administered a pulse of the nucleotide bromodeoxyuridine (BrdU) to rat and mouse pups and, after a long (more than 2-month) chase, examined whether the kidney contained a population of low-cycling cells. We found that in the adult kidney, BrdU-retaining cells were very sparse except in the renal papilla, where they were numerous. During the repair phase of transient renal ischemia, these cells entered the cell cycle and the BrdU signal quickly disappeared from the papilla, despite the absence of apoptosis in this part of the kidney. In vitro isolation of renal papillary cells showed them to have a plastic phenotype that could be modulated by oxygen tension and that when injected into the renal cortex, they incorporated into the renal parenchyma. In addition, like other stem cells, papillary cells spontaneously formed spheres. Single-cell clones of these cells coexpressed mesenchymal and epithelial proteins and gave rise to myofibroblasts, cells expressing neuronal markers, and cells of uncharacterized phenotype. These data indicate that the renal papilla is a niche for adult kidney stem cells.

The renal papilla is a niche for adult kidney stem cells

Many adult organs contain stem cells, which are pluripotent and are involved in organ maintenance and repair after injury. In situ, these cells often have a low cycling rate and locate in specialized regions (niches). To detect such cells in the kidney, we administered a pulse of the nucleotide bromodeoxyuridine (BrdU) to rat and mouse pups and, after a long (more than 2-month) chase, examined whether the kidney contained a population of low-cycling cells. We found that in the adult kidney, BrdU-retaining cells were very sparse except in the renal papilla, where they were numerous. During the repair phase of transient renal ischemia, these cells entered the cell cycle and the BrdU signal quickly disappeared from the papilla, despite the absence of apoptosis in this part of the kidney. In vitro isolation of renal papillary cells showed them to have a plastic phenotype that could be modulated by oxygen tension and that when injected into the renal cortex, they incorporated into the renal parenchyma. In addition, like other stem cells, papillary cells spontaneously formed spheres. Single-cell clones of these cells coexpressed mesenchymal and epithelial proteins and gave rise to myofibroblasts, cells expressing neuronal markers, and cells of uncharacterized phenotype. These data indicate that the renal papilla is a niche for adult kidney stem cells.

Edge-to-edge mitral valve repair: the Columbia Presbyterian experience

BACKGROUND

The edge-to-edge mitral valve repair, first described by Alfieri in 1995 treats mitral regurgitation when standard reparative techniques are difficult, unlikely to succeed, or have failed. This study examines one institution's medium-term experience with this procedure.

METHODS

This study involved patients undergoing edge-to-edge mitral valve repair at a single institution from 1997 to 2003. Preoperative and postoperative echocardiograms were compared. Postoperative morbidity was examined including need for reoperation and long-term medical management. Thirty-day survival and long-term actuarial survival were also determined.

RESULTS

Seventy-one patients comprised this study. Mitral regurgitation on echocardiogram went from 3.43 +/- 0.86 to 0.39 +/- 0.61 (p < 0.001) following repair. Thirty-day mortality was 3 of 71 (4.2%) patients. Actuarial survivals at 24 and 60 months were 84.5% and 58.3%, respectively; adjusted excluding noncardiac death they were 89.5% and 82.3%, respectively. Forty (56.3%) patients had concomitant ring placement and experienced similar survival to those repaired with the bow-tie stitch alone. Home telephone follow-up was conducted, and current medical therapy was determined on 51 patients; 59% were on a beta-blocker, 31% were on an angiotensin-converting enzyme (ACE) inhibitor, 27% were on a diuretic, and 22% were on digoxin. All were New York Heart Association (NYHA) class I or II. Three patients (4.2%) underwent mitral valve reoperation after a mean of 299 +/- 429 days. In no case did the bow-tie suture rupture.

CONCLUSIONS

Edge-to-edge mitral valve repair is a valuable tool in the armamentarium available to treat complex cases of mitral insufficiency or as an adjunct to standard repair techniques that fail to achieve an acceptable result.

Magnetic resonance imaging to detect acute cerebral events in on-pump and hybrid-pump patients

BACKGROUND

Conventional cardiopulmonary bypass results in cerebral ischemic sequelae that may be reduced with hybrid pump technologies, such as the CardioVention system (CardioVention, Santa Clara, CA, USA). CardioVention differs from conventional bypass in that it has a novel air elimination module and reduced membrane surface area and priming volume. This preliminary study tested whether this pump confers neurological safety advantages over conventional bypass.

METHODS

Ten patients were studied, with 6 assigned to on-pump coronary artery bypass grafting and 4 to the CardioVention system. No patients had any stroke history. Within 72 hours postsurgery, each underwent diffusion-weighted magnetic resonance imaging, a sensitive test for cerebral ischemic events.

RESULTS

Two on-pump patients (33%) had postoperative findings on imaging, but none of the CardioVention patients demonstrated comparable changes ( P =.47). No patients had symptoms of acute stroke.

CONCLUSION

Postoperative magnetic resonance imaging showed a trend toward a greater rate of ischemic events in patients undergoing traditional on-pump surgery. These preliminary findings suggest that hybrid pump technologies, such as the CardioVention system, may attenuate the risk of short-term neurological complications. Future studies are indicated to confirm these subclinical ischemic changes and to correlate them with long-term neurocognitive changes.

Robotic techniques improve quality of life in patients undergoing atrial septal defect repair

BACKGROUND

Minimally invasive cardiac surgery has emerged as an alternative to conventional, open surgery. Although most studies of robotically assisted cardiac surgery have reported morbidity and mortality, few have addressed outcome measures, such as pain and quality of life, which was the aim of this study.

METHODS

Eleven patients with atrial septal defects (ASD), and five patients with patent foramen ovale, underwent repair using the Da Vinci system (Intuitive Surgical, Mountain View, CA). The Medical Outcomes Study Short Form Survey (SF-36), along with two additional questions, were administered to these patients on postoperative day 30, along with a similar number of patients who underwent ASD repair by mini-thoracotomy or sternotomy. Quality of life endpoints included bodily pain, vitality, mental health, general health, physical function, and social function.

RESULTS

Robotic patients demonstrated significantly higher scores in 6 of the eight variables (p < 0.05). There was no significant difference in intensive care unit or overall hospital stay among the groups (p = NS). Robotic patients returned to work after 40.2 +/- 30.2 days, mini-thoracotomy patients after 45.6 +/- 27.9 days, and sternotomy patients after 51.7 +/- 40.2 days (p = 0.767). There were no significant differences in SF-36 scores between patients who underwent mini-thoracotomy and sternotomy approaches.

CONCLUSIONS

Closure of an ASD can be performed safely and effectively via an endoscopic approach. Robotic technology minimized the degree of invasiveness, hastened postoperative recovery, and improved quality of life, although length of hospital stay was unchanged.