Imperforate cor triatriatum dexter with patent foramen ovale and pulmonic stenosis in three dogs: Diagnostic findings and attempted surgical correction.

Three canines were identified with aberrant drainage of the caudal vena cava to the left atrium, consistent with imperforate cor triatriatum dexter, and concurrent patent foramen ovale. All three had concurrent significant pulmonic stenosis with varying degrees of hypoplasia of the right ventricular outflow tract. Echocardiography, positive contrast studies, and angiography confirmed the diagnosis. Surgical redirection of the caudal vena cava bloodflow to the right atrium was attempted unsuccessfully in two symptomatic patients. The third patient was asymptomatic, and correction was not attempted. Possible embryologic causes and possible approaches in future cases are discussed.

Favorable outcome after composite valve-graft replacement in patients older than 65 years.

BACKGROUND: Concomitant surgical replacement of the aortic valve and ascending aorta is an ideal treatment for aortic root aneurysms, but there may be hesitation in its use in older patients, despite their known increased risk of rupture. This study was conducted to examine our results in 84 patients older than 65 years undergoing elective aortic root resection with composite valve-graft replacement. METHODS: Eighty-four patients older than 65 years were operated on between June 1987 and August 1998. Median age was 74 years (range, 66 to 89 years), and 57 patients were men. Seventeen patients were undergoing reoperation. Aortic insufficiency was present in 70 patients. Forty-seven patients received a conduit using a bioprosthesis, whereas in 37 a mechanical valved conduit (St. Jude) was used. The ascending aorta alone was replaced in 23 patients; 50 had hemi-arch replacement, and in 11 the entire aortic arch was replaced. RESULTS: Hospital mortality was 8.3% (7 of 84). Sixteen late deaths (19%) were noted during a median follow-up of 3.2 years (range, 0 to 10 years). Only one late death was aorta-related. The incidence of thrombotic or hemorrhagic complications was 2.1/100 patient-years, with equal frequency for both mechanical and bioprosthetic valves. CONCLUSIONS: We conclude that composite valve-graft replacement in elderly patients results in a low operative mortality, yields excellent long-term survival, and averts fatal aneurysm rupture in this high-risk population.

Neurologic outcome after ascending aorta-aortic arch operations: effect of brain protection technique in high-risk patients.

OBJECTIVE: We sought to assess the optimal strategy for avoiding neurologic injury after aortic operations requiring hypothermic circulatory arrest. METHODS: All 717 patients who survived ascending aorta-aortic arch operations through a median sternotomy since 1986 were examined for factors influencing stroke. Temporary neurologic dysfunction was assessed in all patients who survived the operation without stroke since 1993. Multivariate analyses were carried out to determine independent risk factors for neurologic injury. RESULTS: Independent risk factors for stroke were as follows: age greater than 60 years (P <.001; odds ratio, 4.5); emergency operation (P =.02; odds ratio, 2.2); new preoperative neurologic symptoms (P =.05; odds ratio, 2.9); presence of clot or atheroma (P <.001; odds ratio, 4.4); mitral valve replacement or other concomitant procedures (P =.055; odds ratio, = 3.7); and total cerebral protection time, defined as the sum of hypothermic circulatory arrest and any retrograde or antegrade cerebral perfusion (P =.001; odds ratio, 1.02/min). In 453 patients surviving operations without stroke after 1993, independent risk factors for temporary neurologic dysfunction included age (P <.001; odds ratio, 1.06/y), dissection (P =.001; odds ratio, 2.2), need for coronary artery bypass grafting (P =.006; odds ratio, 2.1) or other procedures (P =.023; odds ratio, 3.4), and total cerebral protection time (P <.001; odds ratio, 1.02/min). When all patients with total cerebral protection times between 40 and 80 minutes were examined, the method of cerebral protection did not influence the occurrence of stroke, but antegrade cerebral perfusion resulted in a significant reduction in incidence on temporary neurologic dysfunction (P =.05; odds ratio, 0.3). CONCLUSIONS: The occurrence of stroke is principally determined by patient- and disease-related factors, but use of antegrade cerebral perfusion can significantly reduce the occurrence of temporary neurologic dysfunction.

Molecular genetics in IgA nephropathy.

Evidence from both genotypic and phenotypic perspectives is considered that patients may be genetically predisposed to IgA nephropathy (IgAN) or Henoch-Schönlein purpura (HSP) or that a factor(s) might exclusively contribute to their progression to chronic renal failure. In contrast to most other renal diseases, both IgAN and HSP are uncommon in blacks; this is unexplained but is not due to their low frequency of the A2m(1) allotype. The association of these diseases or their progression with a variety of abnormalities of IgA immunobiology in patients and their families has not been linked to any genotype; similarly, no HLA antigen has been positively or negatively associated in any consistent way. Although complement factor 3 universally accompanies IgA glomerular deposition, complement pathway abnormalities are only sporadically reported with either IgA deposition or disease progression. Whether angiotensin-related polymorphism including the converting enzyme alleles have a specific predictable role, particularly in the progression of renal failure in IgAN, remains problematic. The promising possibility that a structural defect in IgA1 due to an as yet unidentified genetic defect accounts for the deposition of IgA is considered in some detail. Nevertheless, the genetic mechanism(s) of progressive renal failure, whether exclusive to IgAN or to glomerular diseases generally, is of paramount importance.

Is aortic surgery using hypothermic circulatory arrest in octogenarians justifiable?

OBJECTIVE: This study was undertaken to analyze the risk of mortality and neurological complications after aortic surgery requiring hypothermic circulatory arrest (HCA) in octogenarians. METHODS: All patients of >80 years at the time of aortic surgery requiring HCA since 1988 were examined. Of 51 patients, 23 were male; the median age was 83. Twenty-six (51%) had proximal repair; the arch was replaced in eight (16%), and 17 (33%) had descending aorta repair. Eleven (22%) were emergencies. Multivariate analysis was carried out to determine the risk factors for in-hospital mortality and/or stroke (adverse outcome) using variables with P<0.1 after univariate analysis. RESULTS: The hospital mortality was 16%. Five patients suffered strokes (9.8%): only one survived >6 months, and three died before discharge. The overall adverse outcome was 22%, but elective operation was associated with much better results, with an adverse outcome of only 3.6% after operations via a median sternotomy. Adverse outcome was strikingly higher with more distal resections via a left thoracotomy: 47 vs. 8.8% for ascending aorta/arch resections (P=0.003). Emergency operation via a lateral thoracotomy was associated with a prohibitively high adverse outcome. Twenty-nine patients (73%) had temporary neurological dysfunction (TND). Multivariate analysis revealed emergency operation (P=0.01; odds ratio (OR), 10.6) and operations via a lateral thoracotomy (P=0.008; OR, 11) as independent preoperative predictors of adverse outcome. The overall survival was 66% at 2 years and 39% at 5 years, compared with 85 and 52% among age- and sex-matched controls. CONCLUSIONS: Aortic surgery utilizing HCA in octogenarians can be performed with an acceptable risk of mortality and stroke. From the evidence in this study, it seems that elective aneurysm repair via a median sternotomy can be undertaken for the usual indications, even in octogenarians. However, the enhanced vulnerability of the brain in the elderly is reflected by a high early mortality following stroke, and a high incidence of TND. Emergency operations increase the possibility of adverse outcome dramatically, and patients who require a lateral thoracotomy are at significantly higher risk than those operated via a median sternotomy.

Results of immediate surgical treatment of all acute type A dissections.

BACKGROUND: Surgery for acute type A aortic dissection is associated with a high mortality rate and incidence of postoperative complications. This study was designed to explore perioperative risk factors for death in patients with acute type A aortic dissection. METHODS AND RESULTS: One hundred twenty-four consecutive patients with acute type A aortic dissection between 1984 and 1998 were reviewed. All underwent operation with resection of the intimal tear and open distal anastomosis: 107 patients had surgery within 24 hours and 17 patients had surgery within 72 hours of symptom onset. Median age was 62 years (23 to 89); 89 were men. Forty-three patients had ascending aortic replacement only, 72 had hemiarch repair, in 2 the entire arch was replaced, and in 7 replacement included the proximal descending aorta. The aortic valve was replaced in 54 patients, resuspended in 52, and untouched in 18. Hospital mortality rate was 15.3% (19 of 124): of these, 3 patients died during surgery, 4 had fatal rupture of the distal aorta before discharge, and 2 died of malperfusion-related complications. Multivariate analysis revealed age >60, hemodynamic compromise, and absence of hypertension as preoperative indicators of hospital death (P:<0.05); the presence of new neurological symptoms was a significant preoperative risk factor in univariate analysis. Ominous intraoperative factors included contained hematoma and a comparatively low esophageal temperature but not cerebral ischemic time (mean 32 minutes). The site of the intimal tear did not influence outcome, but mortality rate was higher with more extensive resection: 43% with resection including the descending aorta died versus 14% with only ascending aorta or hemiarch replacement. Overall 5- and 10-year survival was 71% and 54%, respectively; among discharged patients (median follow-up 41 months) survival was 84% and 64% versus expected US survival of 92% and 79%. CONCLUSIONS: Immediate surgical treatment of all acute type A dissections with resection of the intimal tear and use of hypothermic circulatory arrest for distal anastomosis results in acceptable early mortality rates and excellent long-term survival.

Pathways for HCO3-reabsorption in mouse medullary collecting duct segments.

To determine pathways of HCO3- reabsorption in the collecting duct of the mouse kidney, the outer medullary collecting duct (OMCD) and the terminal inner medullary collecting duct (IMCDt) were dissected and perfused at 1 to 2 nL/min, and total CO2 was measured by microfluorometry. In the OMCD, net HCO3- flux (JtCO2) was 12.2 +/- 0.7 pmol/min/mm tubule length and decreased to 6.9 +/- 0.6 pmol/min/mm tubule length (n = 5) with 10 mol/L Schering 28080 (SCH) in perfusate (P < .001) and to 7.7 +/- 0.6 pmol/min/mm tubule length (P < .004; n = 4) with 50 micromol/L diethylstilbestrol (DES), an inhibitor of H+-adenosine triphosphatase; together they reduced JtCO2 to 3.7 +/- 0.2 pmol/min/mm tubule length (P = .0002; n = 4). In IMCDt, JtCO2 was 10.9 +/- 1.1 pmol/min/mm tubule length, and it decreased to 4.3 +/- 0.9 pmol/min/mm tubule length (n = 4) with 10 micromol/L SCH in perfusate (P < .05) and to 7.0 +/- 1.1 pmol/min/mm tubule length (P < .05; n = 4) with 50 micromol/L DES; together they decreased JtCO2 to 2.3 +/- 0.3 pmol/min/mm tubule length (P < .002; n = 4). Ouabain (1 mmol/L), an inhibitor of colonic H-K-adenosine triphosphatase (cHKA), in perfusate had no effect on JtCO2 in either segment. Northern hybridization studies showed a high level of expression of gastric HKA (gHKA) in outer medulla and a low level in inner medulla; cHKA expression was undetectable. Thus, in normal mouse OMCD and IMCDt, HCO3- reabsorption is predominantly mediated by gHKA and H+-adenosine triphosphatase and not cHKA. A third isoform of HKA could be present in mouse IMCDt.

Predictors of adverse outcome and transient neurological dysfunction after ascending aorta/hemiarch replacement.

BACKGROUND: This study was undertaken to determine predictors of adverse outcome and transient neurological dysfunction after replacement of the ascending aorta with an open distal anastomosis. METHODS: All 443 patients (300 male, median age 63) undergoing replacement of the ascending aorta with an open distal anastomosis between 1986 and 1998 were included in the analysis. The ascending aorta alone was replaced in 190 (42.9%); 253 (57.1%) also had proximal arch replacement. Median hypothermic circulatory arrest (HCA) time was 25 minutes (range 12 to 68). Either death or permanent neurological dysfunction were considered adverse outcome (AO). RESULTS: Adverse outcome occurred in 11.5% (51 of 443) of patients overall: in 7.4% of elective (20 of 269) or urgent (4 of 54) operations, but in 17% (19 of 113) of emergencies. Multivariate analysis of the group as a whole revealed that significant (p < 0.05) independent preoperative predictors of AO were age greater than 60 [odds ratio (OR) 2.2], hemodynamic instability (OR 2.7), and dissection (OR 1.9). For the 435 operative survivors, procedural variables predictive of AO were contained rupture (OR 2.8) and HCA time (OR 1.03/min). When only the 271 elective patients were analyzed separately, the need for a concomitant procedure (p = 0.009, OR 3.6) and HCA time (p = 0.002, OR 1.06/min) were the only predictors of AO in multivariate analysis. Transient neurological dysfunction (TND) occurred in 86 of 392 patients (22%). Significant predictors of TND for all patients without AO were age (OR 1.06/y), HCA time (OR 1.04/min), coronary artery disease (OR 2.2), hemodynamic instability (OR 3.4), and acute operation (OR 2.2). Survival of discharged patients was 93% at 1 year and 83% at 5 years. CONCLUSIONS: Early elective operation and shorter HCA time during ascending aorta/hemiarch surgery will reduce both AO and TND.

Economics of an academic renal division: an approach.

Nephrology divisions work within the systems and constraints of a department of medicine in a college of medicine, and in an increasing number of cases, also within a larger health care delivery system. Key to the division's stability are a consistently applied practice pan, how the tenure and clinical track systems function, how teaching funds are distributed, mechanisms of incentive for the division, and its faculty and the ability to establish and maintain reasonable financial reserves, especially for investment in research. Dialysis, transplantation, hypertension, research, and the teaching of medical students, residents, and fellows are the key elements the divisional organization must address. Incentives for faculty performance should be included in all of these areas. The division director must recognize his or her control of earning capacity in the distribution of responsibilities; financial returns as compared with effort involved vary considerably. Three main problems confront the future of our divisions: manpower shortages in nephrology; the effects of managed care systems on nephrology practice; and the future existence and success of departments of internal medicine and academic health centers.

Delayed chronic type A dissection following CABG: implications for evolving techniques of revascularization.

BACKGROUND: Postoperative dissection in some patients is related to manipulation of the aorta and accounts for 3% to 5% of deaths after cardiac surgery. METHODS: Between 1987 and 1999, 109 patients with previous cardiac operations were treated for chronic type A dissection. In 31 of the patients, the etiology was related to aortic manipulation. Twenty-one patients (17 men, 4 women; 67+/-13 years of age) had isolated coronary artery bypass grafting (CABG) as their first operation and were reviewed. The interval between operations was 52.9+/-47.3 months. RESULTS: Reoperation was elective in 11 patients, urgent in 10 patients. Median maximal aortic diameter was 6.8+/-2.1 cm; 9 patients had major aortic insufficiency. The intimal tear was at the partial occlusion clamp site in 12 patients (57.1%), at the cross-clamping site in 4 patients (19.1%), and at the proximal anastomosis in 1 patient (4.8%); 4 patients (19.1%) had multiple tears at several sites. Cystic media necrosis was present in 9.5% of the patients, severe atherosclerosis in 47.6% of the patients, and 42.9% of the patients had both. Nine patients (42.9%) underwent a modified Bentall procedure, 12 patients (57.1%) underwent a supracoronary anastomosis, and all had open distal anastomosis. There were two (9.5%) hospital deaths and three (14.3%) postoperative strokes. Freedom from cardiac or aorta-related mortality was 85.7% at a mean follow-up of 49.3 months. CONCLUSIONS: In patients who develop type A dissection of the aorta after previous CABG, the intimal tear most often is at partial occlusion clamp site. This complication is associated with morbidity and mortality. It remains to be seen whether the use of partial occlusion clamps on the pulsating and often diseased aorta during off-pump coronary artery bypass (OPCAB) will increase the risk of delayed iatrogenic dissections.

Surgical techniques. Aortic arch and deep hypothermic circulatory arrest: real-life suspended animation.

Surgical reconstruction of the aortic arch is a complex procedure requiring careful preoperative analysis of the pathology and forethought toward surgical approach. Development of surgical techniques has brought dramatic improvement survival and reduction of neurological events associated with these procedures, yet significant morbidity is still encountered. New approaches to the patient with these pathologies include antegrade and retrograde perfusions to the brain. Continued research into physiology of hypothermic circulatory arrest offers the promise of pharmacological protection of the brain during aortic reconstruction and potentially development of therapeutic modalities to treat and limit ischemic brain damage.

NH4+ secretion in inner medullary collecting duct in potassium deprivation: role of colonic H+-K+-ATPase.

UNLABELLED: NH4+ secretion in inner medullary collecting duct in potassium deprivation: Role of colonic H+-K+-ATPase. BACKGROUND: In K+ deprivation (KD), gastric (g) H+-K+-ATPase (HKA) is suppressed, whereas colonic (c) HKA is induced in the terminal inner medullary collecting duct (IMCD). We hypothesized that in KD, cHKA is induced and can mediate the secretion of NH4+. METHODS: Rats were sacrificed after 2, 3, 6, or 14 days on regular (NML) or K+-free (KD) diet. mRNA expression of HKA isoforms in terminal inner medulla was examined and correlated with NH4+ secretion in perfused IMCD in vitro. RESULTS: Urinary NH4+ excretion increased after K+-free diet for six days. In terminal inner medulla, cHKA expression was strongly induced, whereas gHKA expression was decreased. NH4+ secretion increased by 62% in KD (JtNH4+ 0.57 vs. 0.92 pmol/min/mm tubule length, P < 0.001). Ouabain (1 mM) in perfusate inhibited NH4+ secretion in KD by 45% (P < 0.002) but not in NML. At luminal pH 7.7, which inhibits NH3 diffusion, NH4+ secretion in IMCD was 140% higher in KD (0.36 vs. 0.15, P < 0.03) and was sensitive to ouabain. ROMK-1 mRNA expression was induced in parallel with cHKA in inner medulla. CONCLUSIONS: These data suggest that in KD, cHKA replaces gHKA and mediates enhanced secretion of NH4+ (and H+) into the lumen facilitated by K+ recycling through ROMK-1.

Surgical treatment of the dilated ascending aorta: when and how?

BACKGROUND: The aorta is considered pathologically dilated if the diameters of the ascending aorta and the aortic root exceed the norms for a given age and body size. A 50% increase over the normal diameter is considered aneurysmal dilatation. Such dilatation of the ascending aorta frequently leads to significant aortic valvular insufficiency, even in the presence of an otherwise normal valve. The dilated or aneurysmal ascending aorta is at risk for spontaneous rupture or dissection. The magnitude of this risk is closely related to the size of the aorta and the underlying pathology of the aortic wall. The occurrence of rupture or dissection adversely alters natural history and survival even after successful emergency surgical treatment. METHODS: In recommending elective surgery for the dilated ascending aorta, the patient's age, the relative size of the aorta, the structure and function of the aortic valve, and the pathology of the aortic wall have to be considered. The indications for replacement of the ascending aorta in patients with Marfan's syndrome, acute dissection, intramural hematoma, and endocarditis with annular destruction are supported by solid clinical information. Surgical guidelines for intervening in degenerative dilatation of the ascending aorta, however, especially when its discovery is incidental to other cardiac operations, remain mostly empiric because of lack of natural history studies. The association of a bicuspid aortic valve with ascending aortic dilatation requires special attention. RESULTS: There are a number of current techniques for surgical restoration of the functional and anatomical integrity of the aortic root. The choice of procedure is influenced by careful consideration of multiple factors, such as the patient's age and anticipated survival time; underlying aortic pathology; anatomical considerations related to the aortic valve leaflets, annulus, sinuses, and the sino-tubular ridge; the condition of the distal aorta; the likelihood of future distal operation; the risk of anticoagulation; and, of course, the surgeon's experience with the technique. Currently, elective root replacement with an appropriately chosen technique should not carry an operative risk much higher than that of routine aortic valve replacement. Composite replacement of the aortic valve and the ascending aorta, as originally described by Bentall, DeBono and Edwards (classic Bentall), or modified by Kouchoukos (button Bentall), remains the most versatile and widely applied method. Since 1989, the button modification of the Bentall procedure has been used in 250 patients at Mount Sinai Medical Center, with a hospital mortality of 4% and excellent long-term survival. In this group, age was the only predictor of operative risk (age > 60 years, mortality 7.3% [9/124] compared with age < 60, mortality 0.8% [1/126], p = 0.02). CONCLUSIONS: This modification of the Bentall procedure has set a standard for evaluating the more recently introduced methods of aortic root repair.

Natural history of descending thoracic and thoracoabdominal aneurysms.

BACKGROUND: A review of 165 patients with chronic dissecting and degenerative aneurysms of the descending thoracic and thoracoabdominal aorta initially managed nonoperatively was carried out to ascertain factors associated with a high risk of rupture. METHODS: Changes in the aneurysms were followed with three-dimensional reconstructions of computed tomograph scans. Risk factors were compared in patients with dissecting and nondissecting aneurysms who experienced rupture, in whom operation was recommended during the course of follow-up, and in those without rupture or operation. RESULTS: Nondimensional variables associated with an enhanced risk of rupture include age, the presence of chronic obstructive pulmonary disease, and even uncharacteristic continued pain. Patients with rupture of dissections had significantly higher blood pressures than survivors, and significantly smaller maximal descending thoracic aortic diameters (median 5.4 cm) than patients with rupture of degenerative aneurysms (median 5.8 cm). The extent of the aneurysm, as reflected by the maximal abdominal aortic diameter, was a significant risk factor for rupture only in nondissecting aneurysms. Mortality from rupture was significantly higher in patients with chronic dissections than in patients with nondissecting aneurysms: 9/10 vs 26/34 (p = 0.004). CONCLUSIONS: Almost 20% of patients followed nonoperatively succumbed to rupture, suggesting that a more aggressive surgical approach toward patients with chronic aneurysms of the descending thoracic and thoracoabdominal aorta is warranted. An individualized risk of rupture within 1 year can now be calculated, and patients whose operative risk is lower than their calculated risk should be offered elective surgery.

Use of somatosensory evoked potentials for thoracic and thoracoabdominal aortic resections.

BACKGROUND: Despite tremendous development in surgical and anesthetic techniques, resection of the thoracic and thoracoabdominal segments of the aorta remain associated with the risk of paralysis. Routine use of somatosensory-evoked potential (SEP) monitoring in patients undergoing surgery of the thoracic aorta has become a standard intra- and postoperative procedure at our institution since its first use in 1993. METHODS: One hundred forty nine (149) thoracic aortic operations were performed during January 1993 through January 1998 using SEP-directed serial sacrifice of paired intercostal arteries. Full, partial, or no cardiovascular bypass was variably used, dictated by anatomy; 49 patients required deep hypothermic circulatory arrest (DHCA). Patients were monitored during both the intraoperative procedure as well for the post-anesthesia period until neurologic stability and/or ability to reproducibly demonstrate lower extremity neurologic competency was established. Postoperative neurologic function was compared to ischemic intervals, extent of aortic resection, number of intercostal arteries sacrificed, type of perfusion, and underlying aortic pathology. RESULTS: Overall mortality in the group was 13 patients (8.7%), with no one cause predominating. Nine patients sustained permanent paraplegia, only 1 of whom lost SEPs during the procedure. Abnormal SEPs were seen in 19 patients, 14 of whom had normal neurologic function after awakening. Three of 19 (15.8%) developed late paraplegia that resolved with medical therapy. Eleven patients (7.4%) developed cerebrovascular accidents (CVA), with the majority (8) appearing in the group undergoing DHCA. The risk of CVA was significantly higher in DHCA patients (p < 0.01) than other patients. No patient with CVA had abnormal SEPs; 4 DHCA patients developed abnormal SEPs, 1 with permanent paralysis. CONCLUSIONS: The routine use of SEP monitoring during thoracic and thoracoabdominal aortic surgery as well as during the postoperative period may be useful in decreasing the observed incidence of paraplegic events associated with these procedures.

Subtypes of acute aortic dissection.

BACKGROUND: This series consists of a 12-year experience with a policy of identifying and replacing the aortic segment containing the primary intimal tear for repair of acute aortic dissection. METHODS: Patients with type A dissection underwent urgent surgery. Patients with type B dissection were referred for surgery based on selective criteria, including aortic dilatation greater than 5 cm. A classification system for acute dissection is described that specifies the site of intimal tear while retaining the clinical relevance of the Stanford system. RESULTS: Of 168 acute dissections, 139 were type A and 29 were type B. The site of intimal tear was as follows: ascending aorta, 83 cases; arch, 32 cases; descending aorta, 29 cases; multiple tears, 11 cases (10 included arch tears); no tear (intramural hematoma), 6 cases; not noted, 7 cases. Only 60% of acute type A dissections arose from solitary intimal tears in the ascending aorta, whereas 30% had arch tears. Hospital mortality for type A dissection was 13.7% (18.8% for arch tears, NS) and 0% for type B. False lumen patency was 57.1% for type A dissection and 18.8% for type B dissection (p = 0.002), yet survival was similar for these groups. Ten-year survival for type A dissection with arch tear (0.51 +/- 0.12) was lower than 10-year survival for type A dissection with ascending tear (0.74 +/- 0.05; p = 0.77), and significantly lower than for type A dissection with descending tear (0.88 +/- 0.12; p = 0.029). CONCLUSIONS: Systematic resection of the primary tear yielded similar hospital mortality, 5-year survival, and aorta-related event-free survival rates for subtypes of acute type A dissection. Excellent results were obtained with a selective approach to type B dissection.

HCO-3 reabsorption in renal collecting duct of NHE-3-deficient mouse: a compensatory response.

Mice with a targeted disruption of Na+/H+ exchanger NHE-3 gene show significant reduction in HCO-3 reabsorption in proximal tubule, consistent with the absence of NHE-3. Serum HCO-3, however, is only mildly decreased (P. Schulties, L. L. Clarke, P. Meneton, M. L. Miller, M. Soleimani, L. R. Gawenis, T. M. Riddle, J. J. Duffy, T. Doetschman, T. Wang, G. Giebisch, P. S. Aronson, J. N. Lorenz, and G. E. Shull. Nature Genet. 19: 282-285, 1998), indicating possible adaptive upregulation of HCO-3-absorbing transporters in collecting duct of NHE-3-deficient (NHE-3 -/-) mice. Cortical collecting duct (CCD) and outer medullary collecting duct (OMCD) were perfused, and total CO2 (net HCO-3 flux, JtCO2) was measured in the presence of 10 microM Schering 28080 (SCH, inhibitor of gastric H+-K+-ATPase) or 50 microM diethylestilbestrol (DES, inhibitor of H+-ATPase) in both mutant and wild-type (WT) animals. In CCD, JtCO2 increased in NHE-3 mutant mice (3.42 +/- 0.28 in WT to 5.71 +/- 0.39 pmol. min-1. mm tubule-1 in mutants, P < 0.001). The SCH-sensitive net HCO-3 flux remained unchanged, whereas the DES-sensitive HCO-3 flux increased in the CCD of NHE-3 mutant animals. In OMCD, JtCO2 increased in NHE-3 mutant mice (8.8 +/- 0.7 in WT to 14.2 +/- 0.6 pmol. min-1. mm tubule-1 in mutants, P < 0.001). Both the SCH-sensitive and the DES-sensitive HCO-3 fluxes increased in the OMCD of NHE-3 mutant animals. Northern hybridizations demonstrated enhanced expression of the basolateral Cl-/HCO-3 exchanger (AE-1) mRNA in the cortex. The gastric H+-K+-ATPase mRNA showed upregulation in the medulla but not the cortex of NHE-3 mutant mice. Our results indicate that HCO-3 reabsorption is enhanced in CCD and OMCD of NHE-3-deficient mice. In CCD, H+-ATPase, and in the OMCD, both H+-ATPase and gastric H+-K+-ATPase contribute to the enhanced compensatory HCO-3 reabsorption in NHE-3-deficient animals.

Rewarding teaching faculty with a reimbursement plan.

OBJECTIVE: To develop a system for measuring the teaching effort of medical school faculty and to implement a payment system that is based on it. DESIGN: An interventional study with outcomes measured before and after the intervention. SETTING: A department of internal medicine with a university hospital and an affiliated Veterans Administration hospital. INTERVENTION: We assigned a value in teaching units to each teaching activity in proportion to the time expended by the faculty and the intensity of their effort. We then calculated total teaching units for each faculty member in the Division of General Internal Medicine and for combined faculty effort in each subspecialty division in the Department of Medicine. After determining the dollar value for a teaching unit, we distributed discretionary teaching dollars to each faculty member in the Division of General Internal Medicine and to each subspecialty division according to total teaching units. MEASUREMENTS AND MAIN RESULTS: The distribution of discretionary teaching dollars was determined. In the year after the intervention, there was a substantial redistribution of discretionary teaching dollars among divisions. Compared with an increase in total discretionary dollars of 11.4%, the change in allocation for individual divisions ranged from an increase of 78.2% to a decrease of -28.5%. Further changes in the second year after the intervention were modest. The distribution of teaching units among divisions was similar to the distribution of questions across subspecialties on the American College of Physicians In-Training Examination (r =.67) and the American Board of Internal Medicine Certifying Examination (r =.88). CONCLUSIONS: It is possible to measure the value of teaching effort by medical school faculty and to distribute discretionary teaching funds among divisions according to the value of teaching effort. When this intervention was used at our institution, there were substantial changes in the amounts received by some divisions. We believe that the new distribution more closely approximates the desired distribution because it reflects the desired emphasis on knowledge as measured by two of the most experienced professional groups in internal medicine. We also believe that our method is flexible and adaptable to the needs of most clinical teaching