Aortic growth rates in chronic aortic dissection

AIM

To determine and compare rates of descending aortic enlargement and complications in chronic aortic dissection with and without a proximal aortic graft.

METHODS AND MATERIALS

Fifty-two patients with dissection involving the descending aorta and who had undergone at least two computed tomography (CT) examinations at our institution between November, 1993 and February, 2004 were identified, including 24 non-operated patients (four type A, 20 type B) and 28 operated patients (type A). CT examinations per patient ranged from two to 10, and follow-up ranged from 1-123 months (mean 49 months, median 38.5 months). On each CT image, the aortic short axis (SA), false lumen (FL), and true lumen (TL) diameters were measured at the longitudinal midpoint of the dissection and at the point of maximum aortic diameter. Complications were tabulated, including aortic rupture and aortic enlargement requiring surgery.

RESULTS

For non-operated patients, the midpoint and maximum point SA, TL, and FL diameters increased significantly over time. For operated patients, the midpoint and maximum point SA and FL diameters increased significantly over time. In both groups, aortic enlargement was predominantly due to FL expansion. Diameter increases in non-operated patients were significantly larger than those in operated patients. The rate of change in aortic diameter was constant, regardless of aortic size. Four non-operated and six operated patients developed aortic complications.

CONCLUSIONS

In patients with a dissection involving the descending thoracic aorta, the FL increased in diameter over time, at a constant rate, and to a greater degree in non-operated patients (mostly type B) compared with operated patients (all type A).

Resolution of Large Azygos Vein Aneurysm Following Stent-Graft Shunt Placement in a Patient with Ehlers-Danlos Syndrome Type IV

Ehlers-Danlos syndrome (EDS) type IV is a rare connective tissue disorder associated with thin-walled, friable arteries and veins predisposing patients to aneurysm formation, dissection, fistula formation, and vessel rupture. Azygos vein aneurysm is an extremely rare condition which has not been reported in association with EDS in the literature. We present a patient with EDS type IV and interrupted inferior vena cava (IVC) with azygos continuation who developed an azygos vein aneurysm. In order to decrease flow through the azygos vein and reduce the risk of aneurysm rupture, a stent-graft shunt was created from the right hepatic vein to the azygos vein via a transhepatic, retroperitoneal route. At 6 month follow-up the shunt was open and the azygos vein aneurysm had resolved.

Implications of increased left ventricular mass index on in-hospital outcomes in patients undergoing aortic valve surgery

BACKGROUND

Increased left ventricular mass index has been shown to be associated with higher mortality in epidemiologic studies. However, the effect of increased left ventricular mass index on outcomes in patients undergoing aortic valve replacement is unknown.

METHODS

We studied 473 consecutive patients undergoing elective aortic valve replacement to assess the influence of left ventricular mass index on outcomes in patients having this procedure. Echocardiographic left ventricular dimensions were used to calculate left ventricular mass index (considered increased if >134 g/m(2) in male patients and >110 g/m(2) in female patients).

RESULTS

Left ventricular mass index was increased in 24% of patients undergoing aortic valve replacement. Postprocedural complications (respiratory failure, renal insufficiency, congestive heart failure, and atrial and ventricular arrhythmias), length of stay in the intensive care unit, and in-hospital mortality were increased in patients with increased left ventricular mass index. Multivariable analysis identified prior valve surgery (odds ratio, 4.3; 95% confidence interval, 1.2-15.7; P =.030), left ventricular ejection fraction (odds ratio, 1.07; 95% confidence interval, 1.01-1.14; P =.020), history of hypertension (odds ratio, 8.2; 95% confidence interval, 2.2-30.4; P =.002), history of liver disease (odds ratio, 50.4; 95% confidence interval, 4.2-609.0; P =.002), and increased left ventricular mass index (odds ratio, 38; 95% confidence interval, 9.3-154.1; P <.001) as independent predictors of in-hospital mortality. Furthermore, low output syndrome was identified as the most common mode of death (36%) after aortic valve replacement in patients with increased left ventricular mass index.

CONCLUSIONS

Increased left ventricular mass index is associated with increased adverse in-hospital clinical outcomes in patients undergoing aortic valve replacement. Although this finding warrants special modification in perioperative management, further studies are needed to address whether outcomes in asymptomatic patients with aortic valve disease could be improved by earlier aortic valve replacement before a significant increase in left ventricular mass index.

Reoperation for Freestyle stentless aortic valves

Ten patients who initially underwent Freestyle stentless aortic valve implantation required reoperation. The goal of this study was to describe the reoperative techniques used and to review the outcomes of reoperation in patients with Freestyle stentless aortic valves. From September 1992 to April 2001, at the University of Michigan, a total of 552 Freestyle stentless aortic valves were implanted, and in 10 (1.8%) of these patients (7 men, 3 women) a reoperation was required. The mean age at the time of the initial implantation was 53.5 +/- 14.1 years. Implantation techniques included both modified inclusion root (7) and inclusion root (3). Reasons for reoperation included endocarditis (7), aortic aneurysm (1), valve dehiscence (1), and subvalvular outflow tract obstruction (1). Eight patients underwent homograft reimplantations and in 2 Freestyle reimplantations. In all cases, the previous aortotomy was re-entered, the pseudoendothelial layer over the distal suture line of the noncoronary sinus was incised and continued into the other 2 sinuses. Utilizing a ganglion knife, the Freestyle valve was freed from the native aortic tissue to the proximal suture line. The Dacron sewing ring was then separated using sharp dissection and the lower suture line excised. No calcification was noted in any case. The mean time interval between the first and second operative procedure was 13.4 +/- 21.5 months. There were no operative deaths and only one late death. Mean long-term follow-up was 43 +/- 29 months. Reoperation on a Freestyle stentless aortic valve, when necessary, can be accomplished without increased operative risk and with excellent survival.

Echocardiographic correlates of Freestyle stentless tissue aortic valve endocarditis

Echocardiography plays a critical role in assessing prosthetic valve endocarditis. Because normal paravalvular findings can mimic paraprosthetic infection early after implantation of a stentless bioprosthesis, we sought to define echocardiographic characteristics associated with infective endocarditis (IE) complicating stentless tissue aortic valve replacement. Between September 1992 and October 2000, 388 patients underwent aortic valve replacement with a Freestyle stentless tissue aortic valve. Nine patients presented with clinical endocarditis 10 days to 107 weeks after surgery. Patients included 8 men and 1 woman, ages 38 to 72 years. Of these, 7 patients underwent valve explantation, 1 patient was treated medically, and 1 died within hours of presentation. Intraoperative post-pump transesophageal echocardiography (TEE) and subsequent TEE examinations were reviewed for pertinent findings. For comparison, 22 patients without IE who underwent follow-up TEE within 1 year after Freestyle aortic valve replacement served as a control group. Abnormal TEE findings in patients with IE included new or worsening paravalvular aortic regurgitation (AR) in 4, diffuse leaflet thickening in 4, valvular vegetations in 1, and aorto-atrial fistula in 1. A progressive increase in the paravalvular echo-dense and/or echo-lucent space occurred in 5 of 9 patients. Among control subjects, paravalvular findings observed on immediate post-pump TEE resolved over time, and did not increase in size in any patient. In addition, no control patient developed new or progressive AR, diffuse leaflet thickening, or vegetations. TEE is useful in detecting valvular and paravalvular involvement of IE complicating stentless tissue aortic valve replacement. Because incremental change in paravalvular appearance from post-pump TEE is an important finding, intraoperative post-pump TEE should be performed and recorded in all patients undergoing stentless tissue aortic valve replacement.

An outbreak of coagulase-negative staphylococcal surgical-site infections following aortic valve replacement

OBJECTIVES

To determine the cause of a coagulase-negative staphylococcal outbreak and to identify risk factors for surgical-site infections among patients following Medtronic Freestyle bioprosthesis implantation.

DESIGN

Retrospective case-control study.

SETTING

An 800-bed university referral center.

PATIENTS

The cohort of 64 patients undergoing Freestyle valve replacement from September 1998 to December 1998.

RESULTS

Seven patients developed infection (10.9% vs 1.1% during the preceding 8 months), including two with mediastinitis and five with endocarditis. There were no statistically significant differences between cases and controls with respect to age, gender, weight, underlying illness, preoperative hospital stay, duration of surgery, time on bypass, central venous catheter duration, National Nosocomial Infection Surveillance risk index, New York Heart Association class, albumin, or antibiotic prophylaxis. However, only three cases were documented to have received vancomycin prophylaxis. Of all staff evaluated, only surgical resident A was significantly associated with infection (odds ratio, 7.68; 95% confidence interval, 1.3-44.1; P=.02) Pulsed-field gel electrophoresis patterns on Staphylococcus epidermidis isolates from four of the six cases were identical. These cases were performed on different days. Surgical resident Awas the only staff member present in the operating room for all cases caused by the epidemic strain. This S epidermidis strain, however, was not isolated from operating room staff.

CONCLUSION

A surgical resident was significantly associated with infection. However, the cause of this outbreak was likely multifactorial. Changes occurring during the investigation included institution of vancomycin as routine prophylaxis and modification of surgical technique, which contributed to the resolution of the outbreak.

Prophylactic mitral reconstruction for mitral regurgitation

BACKGROUND

Mitral regurgitation (MR) will produce myocardial dysfunction. The goal of this study was to review outcomes of mitral valve reconstruction in asymptomatic patients with severe MR.

METHODS

From 1992 to 2000, 93 asymptomatic patients with degenerative disease and severe MR underwent mitral valve reconstruction. Mean preoperative left ventricular internal diameter diastole was 56 +/- 8 mm and ejection fraction was 60% +/- 6%. Mean age was 47 +/- 10 years and mean follow-up 23 +/- 27 months. All patients underwent complex reconstruction.

RESULTS

There were no deaths and two late reoperations. One was for systolic anterior motion of the anterior leaflet of the mitral valve requiring valve replacement and one for hemolysis requiring re-repair. There was one perioperative transient ischemic attack and no late thromboembolic events. At follow-up all but 1 patient remains in NYHA class I and all had no MR except in 2 patients at 63 and 89 months.

CONCLUSIONS

Mitral valve reconstruction for "asymptomatic" MR can be performed with no mortality and low morbidity before development of left ventricular dysfunction. Early prophylactic repair is advocated in the presence of severe MR if valve reparability is assured.

Aortic dissection: CT features that distinguish true lumen from false lumen

OBJECTIVE

The purpose of this study was to determine which CT findings are reliable indicators of the true or false lumen in an aortic dissection.

CONCLUSION

The beak sign and a larger cross-sectional area were the most useful indicators of the false lumen for both acute and chronic dissections. Features generally indicative of the true lumen included outer wall calcification and eccentric flap calcification. In cases showing one lumen wrapping around the other lumen in the aortic arch, the inner lumen was invariably the true lumen.

Effect of postoperative atrial fibrillation on length of stay after cardiac surgery (The Postoperative Atrial Fibrillation in Cardiac Surgery study [PACS(2)]

Atrial fibrillation (AF) after cardiac surgery is thought to increase length of stay (LOS). A clinical pathway focused on the management of postoperative AF, including prophylaxis with beta blockers, was implemented to assess the effect of AF on LOS after cardiac surgery. Data were obtained on consecutive cardiac surgery patients in preoperative normal sinus rhythm, no prior history of AF, and no chronic antiarrhythmic therapy from January to May 1995 (control) and November 1996 to June 1997 (pathway). Statistical analysis was performed to assess the effect of postoperative AF on the LOS, clinical outcomes, and cost after cardiac surgery. Despite the clinical pathway, the LOS (7 days for both periods; p = 0.12) and incidence of AF (28.9% vs 28.4%; p = 0.92) remained unchanged. Unadjusted direct costs were 15% higher in the pathway period (p <0.001). Increased rates of beta-blocker therapy had a marginal effect on the incidence of postoperative AF, except in the group who only underwent primary coronary artery bypass graft surgery (31.2% vs 25.3%; p = 0.31). Multivariate analysis revealed that AF contributed only 1 to 1.5 days to the LOS. Thus, this investigation represents the most recent analysis of the effects of postoperative AF on LOS, clinical outcomes, and cost after cardiac surgery. Unlike prior studies, the impact of postoperative AF is less prominent in the current era of cardiac surgical care regardless of the presence of a clinical pathway addressing AF.

Complete atrioventricular block after valvular heart surgery and the timing of pacemaker implantation

The natural history of patients who developed complete atrioventricular block after valvular heart surgery was investigated to determine the optimal timing for pacemaker implantation. Patients who developed complete atrioventricular block within 24 hours after operation, which then persisted for > 48 hours, were unlikely to recover; such patients could potentially undergo earlier pacemaker implantation if otherwise ready for discharge.

Ulcerlike lesions of the aorta: imaging features and natural history

PURPOSE

To document the natural history of ulcerlike aortic lesions and determine whether any computed tomographic (CT) features predict outcome.

MATERIALS AND METHODS

CT scans from 1994 to 1998 that depicted an ulcerlike aortic lesion were retrospectively evaluated. Features evaluated included lesion and aortic size and intramural hematoma. Initial CT findings were correlated with clinical data and subsequent CT findings.

RESULTS

There were 56 lesions in 38 patients. Follow-up (mean, 18.4 months) CT scans were available for 33 lesions. Stability of the lesion and adjacent aorta was noted in 21 lesions. Two lesions were unchanged, although associated intramural hematoma regressed over 1-2 months. Ten lesions showed mild to moderate increase in aortic diameter (mean follow-up, 19.8 months) either with (seven lesions) or without (one lesion) increase in size of the lesion or with incorporation of the lesion into the aortic wall contour (two lesions). Of all 56 lesions, 37 were clinically stable, two were associated with recurrent chest and/or back pain, eight underwent surgical resection or stent placement, and two were in patients who died. Seven lesions were in patients lost to follow-up. No initial CT feature was predictive of CT outcome, although lack of pleural effusion correlated with clinical stability.

CONCLUSION

Most ulcerlike aortic lesions are asymptomatic and do not enlarge. About one-third of lesions progress, generally resulting in mild interval aortic enlargement.

Impact of high transvalvular velocities early after implantation of Freestyle stentless aortic bioprosthesis

BACKGROUND AND AIM OF THE STUDY

Stentless aortic bioprostheses have excellent hemodynamics, although heterogeneity in gradients has been observed. The present study was intended to determine whether high early postoperative transvalvular velocities correlate with other measures of left ventricular outflow obstruction, whether the phenomenon is transient, and whether high velocities observed early after surgery predict differences in subsequent valve performance or left ventricular remodeling.

METHODS

Sixty-eight consecutive patients who underwent implantation of Freestyle stentless aortic bioprosthesis and survived to hospital discharge underwent early postoperative echocardiography. Peak transvalvular velocity was used to define a 'high-velocity' group, based on mean (+ 1 SD) for the group. Mean pressure gradient, ratio of peak to proximal velocities, and effective orifice area were assessed; change in peak velocity and evidence of left ventricular mass regression were studied at one-year follow up.

RESULTS

Of 68 patients, 14 (21%) had 'high velocities' based on early postoperative peak transvalvular velocity >3.0 m/s. There was a higher prevalence of women (64% versus 33%, p = 0.04), and both body surface area (1.79+/-0.17 versus 1.95+/-0.20 m2, p = 0.01) and implanted valve size (22.9+/-2.0 versus 24.9+/-2.1 mm, p = 0.003) were smaller among the 'high-velocity' group. High velocity correlated with other measures of resistance to left ventricular outflow, including higher mean gradient (20.9+/-6.5 versus 8.3 +/-4.2 mmHg, p <0.001) and lower effective orifice area (1.15+/-0.36 versus 1.69+/-0.62 cm2, p <0.001). High early postoperative velocities persisted at one year in eight of 13 (62%) patients. Left ventricular mass regression occurred less often in the 'high-velocity' group (38% versus 77% of patients, p = 0.03) and was present in only one of eight (12%) patients in whom high velocity persisted at one year.

CONCLUSION

High early postoperative transvalvular velocity suggests resistance to left ventricular outflow. High velocities are transient in some patients, although persistence of high transvalvular velocity suggests 'prosthesis-patient mismatch' with incomplete relief of left ventricular outflow obstruction.

The International Registry of Acute Aortic Dissection (IRAD): new insights into an old disease

CONTEXT

Acute aortic dissection is a life-threatening medical emergency associated with high rates of morbidity and mortality. Data are limited regarding the effect of recent imaging and therapeutic advances on patient care and outcomes in this setting.

OBJECTIVE

To assess the presentation, management, and outcomes of acute aortic dissection.

DESIGN

Case series with patients enrolled between January 1996 and December 1998. Data were collected at presentation and by physician review of hospital records.

SETTING

The International Registry of Acute Aortic Dissection, consisting of 12 international referral centers.

PARTICIPANTS

A total of 464 patients (mean age, 63 years; 65.3% male), 62.3% of whom had type A dissection.

MAIN OUTCOME MEASURES

Presenting history, physical findings, management, and mortality, as assessed by history and physician review of hospital records.

RESULTS

While sudden onset of severe sharp pain was the single most common presenting complaint, the clinical presentation was diverse. Classic physical findings such as aortic regurgitation and pulse deficit were noted in only 31.6% and 15.1% of patients, respectively, and initial chest radiograph and electrocardiogram were frequently not helpful (no abnormalities were noted in 12.4% and 31.3% of patients, respectively). Computed tomography was the initial imaging modality used in 61.1%. Overall in-hospital mortality was 27.4%. Mortality of patients with type A dissection managed surgically was 26%; among those not receiving surgery (typically because of advanced age and comorbidity), mortality was 58%. Mortality of patients with type B dissection treated medically was 10.7%. Surgery was performed in 20% of patients with type B dissection; mortality in this group was 31.4%.

CONCLUSIONS

Acute aortic dissection presents with a wide range of manifestations, and classic findings are often absent. A high clinical index of suspicion is necessary. Despite recent advances, in-hospital mortality rates remain high. Our data support the need for continued improvement in prevention, diagnosis, and management of acute aortic dissection.

Bedside chest radiography as part of a postcardiac surgery critical care pathway: a means of decreasing utilization without adverse clinical impact

OBJECTIVE

To evaluate the use of bedside chest radiography and patient outcome before and after implementation of a cardiac surgery critical care pathway that included guidelines for bedside radiography.

DESIGN

A cohort observational study.

SETTING

A university hospital in the midwest.

PATIENTS

Three groups, of 100 patients each, undergoing cardiac surgery in 1990, 1991, and 1995.

INTERVENTION

Introduction of a critical care pathway.

MEASUREMENTS

Medical records were retrospectively reviewed in three groups of 100 patients each: before the introduction of the critical care pathway; 2 months after introduction of the pathway in 1991; and 4 yrs after introduction in 1995. Data were analyzed to determine operative risk for each group. Subsequent analyses determined bedside radiography use, total length of hospital stay, and patient outcome (mortality rate, complications requiring intervention, and reoperation) during hospitalization and at outpatient follow-up 15-30 days postdischarge.

RESULTS

Total length of hospital stay was shorter for the 1995 group (7.6+/-6.6 days) compared with other groups (prepathway, 11.1+/-10.3 days; 1991 postpathway, 10.2+/-9.6 days; p<.05). The mean numbers of radiographs per patient were as follows: prepathway, 5.1; 1991 postpathway, 5.2; and 1995 postpathway, 3.3. The mean number of radiographs in the 1995 group was significantly lower (p = .02). More patients had the proposed number of two bedside radiographs described in the pathway in the 1995 group compared with the other groups (prepathway, p<.0001; the two-month postpathway group, p = .01). Twenty-three malpositioned catheters/tubes were found in the prepathway and 1991 groups compared with 11 in the 1995 group (p = .02). No statistically significant difference was found in inpatient complications (mediastinal bleeding, pneumothoraces, and pleural effusions), postdischarge complications, reoperations, or mortality rate.

CONCLUSION

Introduction of a critical care pathway can decrease the use of bedside radiography without adversely affecting near-term patient outcomes.

Extracorporeal life support to left ventricular assist device bridge to heart transplant: A strategy to optimize survival and resource utilization

BACKGROUND

The use of extracorporeal life support (extracorporeal membrane oxygenation [ECMO]) as a direct bridge to heart transplant in adult patients is associated with poor survival. Similarly, the use of an implantable left ventricular assist device (LVAD) to salvage patients with cardiac arrest, severe hemodynamic instability, and multiorgan failure results in poor outcome. The use of LVAD implant in patients who present with cardiogenic shock who have not been evaluated for transplantation or who have sustained a recent myocardial infarction also raises concerns. ECMO may provide reasonable short-term support to patients with severe hemodynamic instability, permit recovery of multiorgan injury, and allow time to complete a transplant evaluation before long-term circulatory support with an implantable LVAD is instituted. After acquisition of the HeartMate LVAD (Thermo Cardiosystems, Inc), we began using ECMO as a bridge to an implantable LVAD and, subsequently, to transplantation in selected high-risk patients.

METHODS AND RESULTS

From October 1, 1996, through September 30, 1998, 32 adult patients who presented with refractory cardiogenic shock (cardiac index <2.0 L. min(-1). m(-2), with systolic blood pressure <100 mm Hg and pulmonary capillary wedge pressure >/=24 mm Hg and dependent on >/=2 inotropes with or without intra-aortic balloon pump) were evaluated and accepted as candidates for mechanical assistance as a bridge to transplant. Of the 32 patients, 14 (group I) had a cardiac arrest or severe hemodynamic instability (systolic blood pressure </=75 mm Hg) with evidence of multiorgan failure (defined as serum creatinine level >3 mg/dL or oliguria; international normalized ratio >1.5 or transaminases >5 times normal or total bilirubin >3 mg/dL; and needing mechanical ventilation). Group I patients were placed on ECMO support; 7 underwent subsequent LVAD implant and 1 was bridged directly to transplant. Six patients in group I survived to transplant hospitalization discharge. The remaining 18 patients (group II) underwent LVAD implant without ECMO support; 12 survived to transplant hospitalization discharge and 2 remained alive with ongoing LVAD support and awaited transplant. One-year actuarial survival from the initiation of circulatory support was 43% in group I and 75% in group II. One-year actuarial survival from the time of LVAD implant in group I, conditional on surviving ECMO, was 71% (P=NS compared with group II).

CONCLUSIONS

In appropriately selected high-risk patients, the rate of LVAD survival after initial ECMO support was not significantly different from the survival rate after LVAD support alone. An initial period of resuscitation with ECMO is an effective strategy to salvage patients with extreme hemodynamic instability and multiorgan injury. Use of LVAD resources is improved by avoiding LVAD implant in a very-high-risk cohort of patients who do not survive ECMO.

The impact of new technology on a clinical practice

The use of xenograft stentless tissue valves has increased because of excellent hemodynamics and availability. This article describes the impact of the incorporation of this new technology into a single institutional practice over time. A time span for continual usage of the new stentless Freestyle valve was divided into four distinct chronological groups and evaluated. Data on 266 consecutive patients receiving the Freestyle prosthesis were analyzed with regard to demographics, degree of illness, complexity of surgery, and outcomes to discover any distinct changes over time with respect to experience and acquired confidence and surgical expertise. Findings among the four groups were compared using Student's t-test. The only change in patient demographics was younger age (mean age decreased from 70 to 62 years). The number of procedures rose steadily, and the degree of illness increased as noted in the increase between groups in the percentage of patients with comorbidities (from 45% to 92%). The complexity of surgery score steadily increased (from 1.9 to 2.5); however, the mean cross-clamp time did not change. The surgical mortality rate for the entire study was 3.4%. In group 1, the mortality was 7.5% but decreased rapidly and remained steady throughout the rest of the study. The use of the Freestyle stentless conduit in a single practice over time shows a distinct learning curve. With experience, valves are placed in younger, sicker patients who require more complex surgery. Surgical outcomes and efficiency improve with acquired surgical expertise.

Impact of intraoperative post-pump aortic regurgitation with stentless aortic bioprostheses

Stentless aortic bioprosthesis performance may be affected by geometric distortion, and intraoperative echocardiography typically is used to assess prosthetic valve function. The impact of minimal or mild post-pump aortic regurgitation has not been previously investigated. Intraoperative post-pump transesophageal echocardiograms and follow-up transthoracic echocardiograms (up to 3 years' postoperatively) were reviewed for 96 patients who underwent implantation of Freestyle (Medtronic) stentless aortic bioprostheses. Minimal or mild aortic regurgitation was present post-pump in 50 of 96 (52%) patients. On early follow-up examination (n = 80), no patient had more than mild aortic regurgitation. Aortic regurgitation had completely resolved in 24 of 39 (62%) patients with post-pump aortic regurgitation, including 15 of 19 (79%) patients with minimal paravalvular regurgitation. The incidence of mild aortic regurgitation at 2 and 3 years did not appear different between patients with and those without post-pump aortic regurgitation. Minimal or mild aortic regurgitation is common on intraoperative post-pump transesophageal echocardiography immediately after implantation of stentless aortic bioprostheses. Resolution is common, especially of small paravalvular jets. Minimal or mild post-pump aortic regurgitation infrequently results in even mild aortic regurgitation on early follow-up evaluation and does not appear to predict clinically significant progression of aortic regurgitation on long-term follow-up evaluation.

Fenoldopam: a new parenteral antihypertensive: consensus roundtable on the management of perioperative hypertension and hypertensive crises

A panel of clinicians from anesthesiology, surgery, nephrology, hypertension, cardiology, and pharmacology was convened to discuss pharmacologic therapeutics in the management of hypertensive crisis and perioperative hypertension. The panel discussed the advantages and limitations of currently available parenteral drugs, and assessed the potential use of fenoldopam mesylate, a drug in clinical development since 1981, and recently approved by the U.S. Food and Drug Administration (FDA). Fenoldopam is a dopamine receptor (DA1 selective) agonist that is a systemic and renal vasodilator. It was concluded that fenoldopam offers significant advantages as a parenterally administered agent for the management of blood pressure in both hypertensive emergencies and in the perioperative setting.

Risk analysis for aortic surgery using hypothermic circulatory arrest with retrograde cerebral perfusion

BACKGROUND

Retrospective analysis of 144 patients undergoing aortic arch reconstruction using hypothermic circulatory arrest (HCA) with retrograde cerebral perfusion (RCP) for cerebral protection was performed.

METHODS

The diagnosis, procedure, and anatomic site of the arch anastomosis were analyzed to see if they were independent predictors of mortality or morbidity. In addition age, gender, HCA-RCP times, preoperative malperfusion (both treated and untreated), surgical status, and redo surgery status were also examined to determine their influence on the incidence of death and complications. Both multivariate and univariate analysis were performed using linear regression and cross-tabulation with either chi2 or Fisher's exact test where appropriate.

RESULTS

Preoperative surgical status (emergent) and the presence of untreated preoperative malperfusion were the only variables that were significant independent predictors for mortality (p <0.05). No variable was significant for the prediction of stroke or other complications. The severity of surgery had no bearing on the patient outcome.

CONCLUSIONS

Complex aortic surgery using HCA-RCP can be performed with acceptable risk to the patients.

Synthetic interposition grafts of the thoracic aorta: postoperative appearance on serial CT studies

PURPOSE

To determine the normal postoperative appearance of thoracic aortic interposition grafts on serial CT studies and to document CT detectable complications.

MATERIALS AND METHODS

The 235 CT studies in 114 patients with one or more thoracic aortic interposition grafts were analyzed for the presence or absence of felt rings, felt pledgets, low-attenuation material surrounding the graft, pseudoaneurysm, and dissection flap. A graft was present in the ascending aorta in 93 patients, in the descending aorta in 25, and in the arch in 11.

RESULTS

Low-attenuation material was seen adjacent to the ascending graft in 55%-82% of patients and adjacent to the descending graft in 60%-79% of patients, showing diminishing frequency and thickness over time. CT scans in 30 of 53 patients showed residual low-attenuation material adjacent to the graft more than 1 year after surgery. CT scans in four of 93 patients with ascending grafts and one of 25 patients with descending grafts showed a pseudoaneurysm.

CONCLUSION

CT studies obtained after aortic interposition grafting show characteristic findings. Knowledge of the type of operative procedure and typical location and CT appearance of surgical materials used is important to correctly diagnose or exclude postoperative complications following thoracic aortic interposition grafting.

Aprotinin versus epsilon-aminocaproic acid for aortic surgery using deep hypothermic circulatory arrest

OBJECTIVE

To compare the relative efficacy of aprotinin and epsilon-aminocaproic acid (EACA) in decreasing blood loss and transfusion requirements after aortic surgery involving deep hypothermic circulatory arrest (DHCA).

DESIGN

A retrospective chart review.

SETTING

A university medical center.

PARTICIPANTS

Forty-nine patients who had undergone thoracic aortic surgery with the use of circulatory arrest.

INTERVENTIONS

Charts were examined for variables believed to influence postoperative blood loss, including the use of medications, and for the amount of postoperative chest tube drainage and perioperative transfusion.

MEASUREMENTS AND MAIN RESULTS

Median chest tube output (CTO) at 6 and 12 hours postoperatively was nearly identical in patients treated with aprotinin or EACA (660 and 1,015 v 700 and 950 mL for aprotinin and EACA at 6 and 12 hours, respectively), as were total perioperative blood transfusions. Complications were not significantly different between groups with the exception of a trend toward increased incidence of renal failure in the group receiving EACA.

CONCLUSION

Aprotinin and EACA appear to be equally efficacious in reducing perioperative blood loss and transfusion requirements in patients undergoing aortic surgery involving DHCA. Questions of safety remain about the use of EACA in this setting that could not be addressed by this small retrospective study. A prospective, placebo-controlled study is warranted to confirm the absolute efficacy of these agents and to better define safety issues.

Evaluating and improving the delivery of heart care: the University of Michigan experience

With increasing pressure to curb escalating costs in medical care, there is particular emphasis on the delivery of cardiovascular services, which account for a substantial portion of the current healthcare dollar spent in the United States. A variety of tools were used to improve performance at the University of Michigan Health System, one of the oldest university-affiliated hospitals in the United States. The tools included initiatives to understand outcomes after coronary bypass operations and coronary angioplasty through use of proper risk-adjusted models. Critical pathways and guidelines were implemented to streamline care and improve quality in interventional cardiology, management of myocardial infarction, and preoperative assessment of patients undergoing vascular operations. Strategies to curb unnecessary costs included competitive bidding of vendors for expensive cardiac commodities, pharmacy cost reductions, and changes in nursing staff. Methods were instituted to improve guest services and partnerships with the community in disease prevention and health promotion.

Intraoperative monitoring of danaparoid sodium anticoagulation during cardiovascular operations

PURPOSE

Patients with cardiovascular disorders frequently need anticoagulation for diagnostic studies, surgical procedures, and therapy. Heparin-induced thrombocytopenia is a relatively common complication of heparin therapy that can result in thrombosis and subsequent limb loss or death, necessitating use of alternative anticoagulants.

METHODS

Two patients who needed cardiac surgery had thrombocytopenia induced by exposure to heparin and heparin-coated tubing. Several assays were examined for their ability to monitor intraoperative anticoagulation of a factor Xa inhibitor, danaparoid sodium.

RESULTS

In vitro, celite and kaolin activated dotting times and activated partial thromboplastin time were prolonged linearly in the presence of increasing concentrations of danaparoid sodium. Aprotinin did not alter the linearity of the response but did alter its slope. In vivo, activated clotting times and activated partial thromboplastin time were insensitive to clinically significant changes in danaparoid sodium plasma levels during cardiopulmonary bypass. Correction in activated partial thromboplastin time lagged 2 hours behind clinically important changes in anti-factor Xa levels. Only anti-factor Xa levels were adequate to monitor intraoperative danaparoid sodium levels.

CONCLUSION

Anticoagulation for cardiopulmonary bypass can be successfully performed with danaparoid sodium and intraoperative anti-factor Xa monitoring.

Long-term outcome following case management after coronary artery bypass surgery

Patient outcome following coronary artery bypass grafting (CABG) has come under increasing governmental, social, and economic scrutiny. To insure quality patient outcome after CABG, many new policies and programs have been instituted. One of these, case management, was developed as a tool for identification and quantification of patient clinical sequences and resource utilization. This present study examines the influence of case management on length of stay and patient outcome following CABG. One hundred forty randomized, retrospectively analyzed CABG patients from 1990, prior to case management, were compared against 140 age-and case-matched randomly controlled CABG patients from 1994 after case management was in place. Patients' demographics were similar. The outcome data showed that intensive care unit (ICU) use and total length of stay were significantly decreased. Furthermore, resource utilization as monitored by chest X-ray, electrocardiography, and laboratory testing were decreased as well. Finally, mortality was decreased despite an increase in risk-adjusted acuity of the patients. There appeared to be no effect of gender or age on the benefit derived from case management. These data demonstrate that the influence of case management is beneficial for resource utilization and patient outcome following CABG and that these types of patient care policy advancements should be encouraged.

Intermediate-term outcome of mitral reconstruction in cardiomyopathy

OBJECTIVE

Severe mitral regurgitation is a frequent complication of end-stage cardiomyopathy that contributes to heart failure and predicts a poor survival. We studied the intermediate-term outcome of mitral reconstruction in 48 patients who had cardiomyopathy with severe mitral regurgitation and were operated on between June 1993 and June 1997.

METHODS

Ages ranged from 33 to 79 years (63 +/- 6 years) with left ventricular ejection fractions of 8% to 25% (16% +/- 3%). All patients were receiving maximal drug therapy and were in New York Heart Association class III-IV with severe, refractory 4+ mitral regurgitation. Operatively, all 48 had undersized flexible annuloplasty rings inserted, 7 had coronary bypass grafts for incidental disease, 11 had prior bypass grafts, and 11 also had tricuspid valve repair.

RESULTS

One operative death occurred as a result of right ventricular failure. Postoperative transesophageal echocardiography revealed mild mitral regurgitation in 7 patients and no mitral regurgitation in 41. There were 10 late deaths, 2 to 47 months after mitral reconstruction. The 1- and 2-year actuarial survivals have been 82% and 71%. At a mean follow-up of 22 months, the number of hospitalizations for heart failure has decreased, and 1 patient has had heart transplantation. Significantly, New York Heart Association class improved from 3.9 +/- 0.3 before the operation to 2.0 +/- 0.6 after the operation. Twenty-four months after the operation, left ventricular volume and sphericity have decreased, whereas ejection fraction and cardiac output have increased.

CONCLUSION

Whether this favorable modification of left ventricular function and geometry will persist remains unknown. However, mitral repair for cardiomyopathy with mitral regurgitation allows new strategies for these patients.

Preoperative amiodarone as prophylaxis against atrial fibrillation after heart surgery

BACKGROUND

Atrial fibrillation occurs commonly after open-heart surgery and may delay hospital discharge. The purpose of this study was to assess the use of preoperative amiodarone as prophylaxis against atrial fibrillation after cardiac surgery.

METHODS

In this double-blind, randomized study, 124 patients were given either oral amiodarone (64 patients) or placebo (60 patients) for a minimum of seven days before elective cardiac surgery. Therapy consisted of 600 mg of amiodarone per day for seven days, then 200 mg per day until the day of discharge from the hospital. The mean (+/-SD) preoperative total dose of amiodarone was 4.8+/-0.96 g over a period of 13+/-7 days.

RESULTS

Postoperative atrial fibrillation occurred in 16 of the 64 patients in the amiodarone group (25 percent) and 32 of the 60 patients in the placebo group (53 percent) (P=0.003). Patients in the amiodarone group were hospitalized for significantly fewer days than were patients in the placebo group (6.5+/-2.6 vs. 7.9+/-4.3 days, P=0.04). Nonfatal postoperative complications occurred in eight amiodarone-treated patients (12 percent) and in six patients receiving placebo (10 percent, P=0.78). Fatal postoperative complications occurred in three patients who received amiodarone (5 percent) and in two who received placebo (3 percent, P= 1.00). Total hospitalization costs were significantly less for the amiodarone group than for the placebo group ($18,375+/-$13,863 vs. $26,491+/-$23,837, P=0.03).

CONCLUSIONS

Preoperative oral amiodarone in patients undergoing complex cardiac surgery is well tolerated and significantly reduces the incidence of postoperative atrial fibrillation and the duration and cost of hospitalization.

Surgical delay for acute type A dissection with malperfusion

BACKGROUND

An acute type A aortic dissection is considered a surgical emergency. Review of the risk factors for a type A dissection showed that preoperative malperfusion was associated with a 22% (2/9) intraoperative mortality and an 89% (8/9) hospital mortality. Intraoperative deaths were secondary to pulmonary failure resulting from capillary leak; the remaining patients died of multiorgan failure resulting from reperfusion injury.

METHODS

The surgical delay approach was adopted for malperfused patients, and treatment in these patients included percutaneous reperfusion, with aortic fenestration and branch stenting where appropriate. Twenty patients had a type A dissection and malperfusion shown by pulsed-wave Doppler echocardiography, transesophageal echocardiography, or spiral computed tomographic scanning. Malperfusion was documented by angiography. After reperfusion, all patients' conditions were stabilized in the intensive care unit; intravenous beta-blockers were administered to decrease the maximum rate of increase of left ventricular pressure. Once patients completely recovered from the consequences of malperfusion, surgical repair was performed. Statistical comparison of the non-delay and delay groups was performed using Fisher's exact test and Student's t test. Multiple logistic regression analysis was used to establish independent predictors for mortality.

RESULTS

The mean delay to repair was 20 days (2 to 67 days). Four (31%) patients were discharged home and readmitted for operation. Three patients (15%) died preoperatively, 1 of retrograde dissection and rupture and 2 of reperfusion injury. Seventeen underwent surgical repair, with two deaths (12%); 15 (75%) were discharged, with an average follow-up of 16.8 months (p < 0.003). Delay was the only independent predictor of outcome.

CONCLUSIONS

Patients with an acute type A dissection and malperfusion should undergo percutaneous reperfusion, and surgical repair should be delayed until the reperfusion injury resolves.

Increased sarcolemmal glucose transporter abundance in myocardial ischemia

Many clinical and laboratory studies suggest that an increase in glucose uptake and metabolism by ischemic myocardium helps protect myocardial cells from irreversible injury. We have examined whether increased sarcolemmal abundance of cardiomyocyte glucose transporters plays a role in this adaptive response. We have shown that acute myocardial ischemia in perfused rat hearts results in increased sarcolemmal abundance of the major glucose transporter, GLUT4, by causing translocation of GLUT4 molecules from an intracellular compartment to the sarcolemma. In nonischemic control hearts only 18 +/- 2.8% of GLUT4 molecules were on the sarcolemma whereas in ischemic hearts this increased to 41 +/- 9.3%. Insulin also caused translocation of GLUT4 molecules to the sarcolemma, and resulted in 61 +/- 2.6% of GLUT4 molecules on the sarcolemma. The combination of ischemia and insulin did not result in additive increases in sarcolemmal GLUT4 abundance. In more persistent or chronic ischemia, the other major myocardial glucose transporter, GLUT1, appears to play an important role. The mRNA for this transporter, which is constitutively expressed on cardiomyocyte sarcolemma, was increased 2.0-fold in regions of hibernating myocardium in humans with coronary heart disease as well as in persistently hypoxic rat neonatal cardiomyocytes in primary culture. In neither of these conditions was GLUT4 mRNA expression increased. Thus, acute myocardial ischemia increases sarcolemmal glucose transporter abundance mainly by translocating previously synthesized GLUT4 molecules from an intracellular compartment, whereas more chronic ischemia also increases GLUT1 abundance via enhanced mRNA expression. Increased GLUT1 and GLUT4 abundance may participate in the augmented glucose uptake of ischemic myocardium and therefore may help protect ischemic myocardium from irreversible injury.

The dissected aorta: percutaneous treatment of ischemic complications--principles and results

PURPOSE

Describe the principles and results of percutaneous treatment of ischemic complications of aortic dissection.

MATERIALS AND METHODS

Twenty-four patients with aortic dissection complicated by ischemic compromise of the liver or bowel (n = 15), kidney (n = 18), or lower extremity (n = 13) were evaluated by means of aortography, intravascular ultrasound, and manometry, and were treated percutaneously. Visceral arteries were classified as obstructed or nonobstructed. Obstruction was classified as static, in which the dissecting hematoma extended into and narrowed the lumen of a branch artery, or dynamic, in which the dissection flap prolapsed into the vessel origin or narrowed the true lumen (TL) above it. Treatment consisted of vascular stents alone (n = 4), or balloon fenestration (n = 20) without (n = 8) or with (n = 12) vascular stents.

RESULTS

Obstruction was present in 77 arteries and was static in 12 arteries, dynamic in 45 arteries, static and dynamic in 17 arteries, and indeterminate in three arteries. Percutaneous treatment did not alter false lumen (FL) pressure, but reduced the peak systolic interluminal pressure gradient from 28 mm Hg to 2 mm Hg and restored flow in 71 of 77 arteries (92%). Six patients died within 30 days (25% operative mortality), none as a result of the procedure. Two additional patients died in follow-up from complications of an expanding FL. Technical complications in two patients due to altered hemodynamics after initial intervention were recognized and corrected percutaneously during the same procedure.

CONCLUSIONS

Percutaneous fenestration and endovascular stent deployment are indicated to restore blood flow to arteries compromised by aortic dissection. The prognosis of patients is related to the ischemic injury sustained prior to the percutaneous interventional procedure and, in patients with acute type I dissection who have not undergone surgery, to the preoperative stability of the FL.

Mediators of ischemia-reperfusion injury of rat lung

In rats, we characterized the mediators of lung reperfusion injury after ischemia. Animals underwent left lung ischemia. After 90 minutes of ischemia, reperfusion for up to 4 hours was evaluated. Lung injury, as determined by vascular leakage of serum albumin, increased in ischemic-reperfused animals when compared with time-matched sham controls. Injury was biphasic, peaking at 30 minutes and 4 hours of reperfusion. The late but not the early phase of reperfusion injury is known to be neutrophil dependent. Bronchoalveolar lavage of ischemic-reperfused lungs at 30 minutes and 4 hours of reperfusion demonstrated increased presence of serum albumin, indicative of damage to the normal vascular/airway barrier. Lung mRNA for rat monocyte chemoattractant protein-1 and tumor necrosis factor-alpha peaked very early (between 0.5 and 1.0 hour) during the reperfusion process. Development of injury was associated with a decline in serum complement activity and progressive intrapulmonary sequestration of neutrophils. Administration of superoxide dismutase before reperfusion resulted in reduction of injury at 30 minutes of reperfusion. Complement depletion decreased injury at both 30 minutes and 4 hours of reperfusion. Requirements for tumor necrosis factor-alpha, interferon-gamma, and monocyte chemoattractant protein-1 for early injury were shown whereas only tumor necrosis factor-alpha was involved at 4 hours. We propose that acute (30-minute) lung injury is determined in large part by products of activated lung macrophages whereas the delayed (4-hour) injury is mediated by products of activated and recruited neutrophils.

The dissected aorta: part III. Anatomy and radiologic diagnosis of branch-vessel compromise

PURPOSE

To determine the anatomic, hemodynamic, and radiologic characteristics of branch-vessel compromise in patients with aortic dissection.

MATERIALS AND METHODS

Sixty-two patients with aortic dissection were evaluated with aortography (n = 62), intravascular ultrasound (US) (n = 35), and manometry (n = 56). Branch-vessel compromise with ischemia was suspected in 40 of these patients. Radiologic and manometric findings were correlated with clinical findings of ischemia. Femoral artery pulse strength was correlated with access from the respective femoral artery to the true and false lumina of the dissected aorta.

RESULTS

Twenty-six of 40 patients suspected of having ischemia had angiographic evidence of branch-vessel compromise, and intravascular US helped identify two types of branch-vessel compromise in them: static (dissection intersected and narrowed the vessel origin) and dynamic (dissection spared the vessel origin, but the dissection flap appeared to compress the true lumen at or above the origin and covered the origin). False-lumen pressure in classic dissections exceeded (n = 16) or equaled (n = 30) true-lumen pressure. Branch vessels that arose exclusively from the false lumen were well perfused. Findings of a dissection flap oriented concave toward the false lumen were 91% sensitive and 72% specific for a true-lumen pressure deficit.

CONCLUSION

Intravascular US and manometric findings clarify the mechanisms of branch-vessel compromise after aortic dissection and provide a rational guide for percutaneous treatment.

Mitral valve reconstruction for active and healed endocarditis

BACKGROUND

Mitral valve reconstruction rather than replacement for mitral insufficiency offers a number of well-accepted benefits. However, the feasibility and results of reconstruction for endocarditis remain largely unknown.

METHODS AND RESULTS

We reviewed 22 consecutive patients referred to the Thoracic Surgical Service at the University of Michigan from January 1, 1991, through October 1, 1995, who underwent mitral valve reconstruction for mitral insufficiency caused by isolated mitral valve endocarditis. Mean age, preoperative ejection fraction, and New York Heart Association (NYHA) functional class were 53 +/- 15 years, 54 +/- 12%, and 3.2 +/- 0.8, respectively. Seven patients had early operation because of septic embolization, persistent infection, or refractory heart failure. Fifteen were cured of infection and were operated on for progressive symptomatic heart failure and left ventricular dilation. Preoperative transesophageal echocardiograms demonstrated severe mitral insufficiency in 20 patients. Valvular pathology noted at operation included annular (6 patients) or leaflet calcification (2), chordal rupture (13), leaflet vegetations (11), annular abscess (3), annular dilation (18), flail leaflet (12), leaflet prolapse (17), chordal shortening (1), and mitral stenosis (1). Mitral valve reconstruction included debridement of infected tissue and implantation of an annuloplasty ring (20 of 22 patients), as well as other complex techniques. Postrepair transesophageal echocardiograms demonstrated mild mitral insufficiency in 6 patients and none in 16 patients. There were no operative or in hospital deaths. Mean follow-up was 20 +/- 14 months. One late death occurred at 30 months. At follow-up, 90% of surviving patients were in NYHA functional class I or II.

CONCLUSIONS

Mitral valve reconstruction for active or healed endocarditis can be performed with low operative morbidity and mortality and yields excellent functional results. Although longer-term follow-up is mandatory, these data support strong consideration of mitral valve reconstruction rather than mitral valve replacement for mitral insufficiency secondary to endocarditis.

Regulatory effects of interleukin-10 on lung ischemia-reperfusion injury

OBJECTIVE

Interleukin-10, a cytokine with antiinflammatory activities, was studied to determine its effects on development of early lung reperfusion injury.

METHODS

Adult male rats underwent 90 minutes of left lung ischemia followed by 4 hours of reperfusion. Time-matched sham-operated control rats underwent hilar dissection but not lung ischemia. Lung injury was measured by vascular permeability to bovine serum albumin tagged with iodine 125. To evaluate the effect of exogenous interleukin-10, additional animals received interleukin-10 intravenously before ischemia. To assess the role of endogenous interleukin-10, animals received rabbit antimouse interleukin-10 immunoglobin G (or preimmune rabbit immunoglobin G) before ischemia.

RESULTS

Compared with sham control rats, ischemia-reperfusion control rats demonstrated significantly more lung injury. Animals receiving interleukin-10 had significantly less lung injury than did ischemia-reperfusion control rats. Animals receiving antiinterleukin-10 had significantly more lung injury than did animals receiving preimmune immunoglobin G. Alveolar macrophages from animals after 90 minutes of lung ischemia produced more tumor necrosis factor-alpha in culture than did unstimulated macrophages; this production was reduced significantly by the addition of interleukin-10 to the culture medium.

CONCLUSION

Endogenous interleukin-10 has a protective effect against early lung reperfusion injury, and interleukin-10 administration can reduce lung reperfusion injury, perhaps in part through its ability to reduce production by alveolar macrophages of tumor necrosis factor-alpha, a known proinflammatory cytokine.

Evaluation of thoracic aortic disease with the use of helical CT and multiplanar reconstructions: comparison with surgical findings

PURPOSE

To assess the accuracy of helical computed tomography (CT) in differentiating different types of thoracic aortic disease, to determine the incremental value of multiplanar reconstructions, and to determine if helical CT could help to reliably predict the need for intraoperative hypothermic circulatory arrest.

MATERIALS AND METHODS

Forty-nine patients underwent pre-operative helical CT with multiplanar reconstructions. Images were reviewed for type and location of pathologic lesions and for features that indicated the need for hypothermic circulatory arrest. The incremental yield of multiplanar reconstructions compared with that of axial images was assessed. Imaging findings were compared with surgical findings.

RESULTS

The types of lesions present in the patients included 36 aneurysms (three were ruptured), six penetrating ulcers, five dissections, and two pseudoaneurysms. The accuracy of diagnosis was 92% (45 of 49 patients) with the use of CT (both with and without multiplanar reconstruction). The necessity of hypothermic circulatory arrest was successfully predicted in 94% (45 of 48 patients) of cases.

CONCLUSION

Helical CT, both with and without the use of multiplanar reconstruction, enabled highly accurate differentiation among diseases of the thoracic aorta and prediction of the need for hypothermic circulatory arrest.

Three-dimensional gadolinium-enhanced MR angiography of the thoracic aorta

OBJECTIVE

Our objective was to evaluate image quality and preliminary clinical experience with three-dimensional gadolinium-enhanced MR angiography of the thoracic aorta.

SUBJECTS AND METHODS

Ninety patients with suspected thoracic aorta pathology underwent 97 MR examinations at 1.5 T with a 4-min, three-dimensional spoiled gradient-echo techniques. Gadolinium infusion was timed for maximum arterial contrast during acquisition of the central portion of K-space. No ECG gating or breath-holding was used. All MR examinations were evaluated retrospectively for intravascular signal-to-noise ratio (SNR). In 30 of the 90 patients, results from surgery (n = 11), angiography (n = 12), or both (n = 7) were available. Four radiologists who were unaware of the angiographic or surgical findings assessed each of these 30 examinations for three types of pathology: dissection, coarctation, or aneurysm. The observers also assessed aortic branch vessel patency and vascular anomalies in the 19 patients who had angiographic correlation.

RESULTS

Image quality (determined as SNR) was highest in the aortic arch, upper descending thoracic aorta, and upper abdominal aorta. We saw a small reduction in the SNR in the ascending aorta and lower descending thoracic aorta (p < .0001), attributable to cardiac and respiratory motion. Image quality was not affected by slow flow. MR imaging correctly diagnosed pathology in all 30 patients with angiographic or surgical correlation, including eight dissections, three coarctations, and 10 aneurysms. The type of the dissection was correctly determined in all eight patients. Stenoses of major branch vessel origins were detected with a sensitivity of 90% (95% bayesian confidence interval, 99-63%) and a specificity of 96% (95% bayesian confidence interval, 99-89%) in the 19 patients with angiographic correlation. Five vascular anomalies, including an aberrant right subclavian artery, a bovine arch, and three accessory renal arteries, were correctly identified.

CONCLUSION

Three-dimensional gadolinium-enhanced MR angiography has the potential to accurately diagnose aortic dissection, coarctation, and aneurysm. It does not require ECG gating or breath-holding and thereby extends the diagnostic utility of MR imaging for the thoracic aorta.

Restricted V beta usage by T cells infiltrating rejecting human lung allografts

TCR expression was evaluated in lung transplant patients to determine whether T cells infiltrating rejecting lung allografts employed restricted V beta elements. Serial bronchoalveolar lavage (BAL) specimens were obtained from six lung transplant recipients at approximately 3 wk, 6 wk, and 3 mo post-transplant. T cell lines were established by culturing lavage cells with irradiated donor splenocytes in the presence of low dose IL-2 for 3 wk, and TCR V beta usage was determined by quantitative reverse transcriptase-PCR. Patients were grouped into three categories based on TCR V beta profiles and the clinical status of the allograft. 1) In one patient, BAL-derived T cells expressed heterogeneous V beta repertoires at all time points evaluated. This patient did not experience graft rejection during the 16-mo period of observation, though respiratory infections were diagnosed. 2) In three patients, V beta usage by BAL-derived T cells was restricted during allograft rejection episodes, but was heterogeneous in the absence of rejection and during respiratory infections. In one of these patients, similar V beta repertoires were employed by BAL cells during multiple rejection episodes. 3) In two patients, restricted V beta usage by BAL-derived T cells was observed before and during rejection episodes. Collectively, these data illustrate that human lung allograft rejection, but not pulmonary infection, is associated with T cells expressing a limited number of V beta families. Restricted V beta usage by graft-reactive T cells may allow for the selective elimination of these cells using TCR-specific reagents, thereby promoting allograft-specific tolerance.

Restricted V beta usage by T cells infiltrating rejecting human lung allografts

TCR expression was evaluated in lung transplant patients to determine whether T cells infiltrating rejecting lung allografts employed restricted V beta elements. Serial bronchoalveolar lavage (BAL) specimens were obtained from six lung transplant recipients at approximately 3 wk, 6 wk, and 3 mo post-transplant. T cell lines were established by culturing lavage cells with irradiated donor splenocytes in the presence of low dose IL-2 for 3 wk, and TCR V beta usage was determined by quantitative reverse transcriptase-PCR. Patients were grouped into three categories based on TCR V beta profiles and the clinical status of the allograft. 1) In one patient, BAL-derived T cells expressed heterogeneous V beta repertoires at all time points evaluated. This patient did not experience graft rejection during the 16-mo period of observation, though respiratory infections were diagnosed. 2) In three patients, V beta usage by BAL-derived T cells was restricted during allograft rejection episodes, but was heterogeneous in the absence of rejection and during respiratory infections. In one of these patients, similar V beta repertoires were employed by BAL cells during multiple rejection episodes. 3) In two patients, restricted V beta usage by BAL-derived T cells was observed before and during rejection episodes. Collectively, these data illustrate that human lung allograft rejection, but not pulmonary infection, is associated with T cells expressing a limited number of V beta families. Restricted V beta usage by graft-reactive T cells may allow for the selective elimination of these cells using TCR-specific reagents, thereby promoting allograft-specific tolerance.

Mitral valve reconstruction in elderly, ischemic patients

The role of mitral valve reconstruction is controversial in elderly patients with concurrent ischemic heart disease owing to technical difficulty, prolonged operative times, high mortality, and possible residual mitral regurgitation. However, mitral reconstruction could be most beneficial in this age group due to preservation of left ventricular function, avoidance of anticoagulation, or repeat operation for bioprosthetic degeneration. We studied the outcome of mitral valve reconstruction in 100 consecutive elderly ischemic patients 65 years or older (mean = 73 years; range, 65 to 86 years) operated on between October 1990 and May 1995. Preoperatively all patients were New York Heart Association (NYHA) class III or IV with an ejection fraction of 32 +/- 2%. All patients underwent primary coronary bypass grafting (2.7 +/- 0.2 grafts) and had a flexible mitral annuloplasty ring inserted. Additionally, 54 patients required further complex mitral repairs. All patients had 4+ mitral regurgitation by transesophageal echocardiography prior to operation. After mitral reconstruction, no patient had more than 1+ regurgitation, while most had none and no systolic anterior leaflet motion was noted. There were 4 early (30 day) deaths (4%) and 6 late deaths (6%) at a mean follow-up of 25 months. Patient morbidity has included episodes of mild congestive heart failure (nine), transient ischemic attack (one), endocarditis (one), and respiratory failure (five). There have been one early and two late reoperations for mitral valve replacement. All remaining patients are in NYHA class I or II. While longer-term follow-up is mandatory, coronary bypass grafting and mitral valve reconstruction in the elderly can be accomplished with acceptable surgical mortality and morbidity, yielding reliable improvement in symptoms and quality of life.

Disparate effects of nitric oxide on lung ischemia-reperfusion injury

BACKGROUND

Inhaled nitric oxide (.NO) has been found to be a potent pulmonary vasodilator. We assessed whether .NO, through this function or others, could alleviate lung reperfusion injury.

METHODS

Rats underwent thoracotomy, with clamps used to create left lung ischemia. After 90 minutes of ischemia, clamps were released, permitting reperfusion for either 30 minutes or 4 hours. Additional animals received inhaled .NO via the ventilator to determine its effects on reperfusion injury.

RESULTS

Lung injury, measured by increased vascular permeability using iodine-125-labeled bovine serum albumin leakage, was significantly increased in ischemic-reperfused animals compared with time-matched shams not undergoing ischemia. Inhaled .NO delivered at the start of reperfusion worsened injury at 30 minutes but was protective at 4 hours. The increased injury could be avoided either by delaying .NO for 10 minutes or by treating the animals with superoxide dismutase before reperfusion. .NO reversed postischemic pulmonary hypoperfusion at 4 hours, as measured by labeled microspheres. Lung neutrophil content was significantly reduced at 4 hours in .NO-treated animals.

CONCLUSIONS

.NO is toxic early in reperfusion, due to its interaction with superoxide, but is protective at 4 hours of reperfusion, due to reversal of postischemic lung hypoperfusion and reduction of lung neutrophil sequestration.

Accuracy of intraoperative transesophageal echocardiography for estimating the severity of functional mitral regurgitation

Although intraoperative transesophageal echocardiography (TEE) is used to guide mitral valve reconstructive procedures, the effects of hemodynamic alterations accompanying general anesthesia on mitral regurgitation (MR) are unknown. This study was performed to evaluate the effect of general anesthesia on MR jet size using TEE with color Doppler imaging in patients undergoing mitral valve surgery. Matched preoperative TEEs performed with the patient under intravenous conscious sedation, and intraoperative studies performed with the patient under general anesthesia were retrospectively reviewed in 46 patients undergoing mitral valve surgery. Patients were divided into groups based on etiology of MR, including 21 patients with myxomatous degeneration and leaflet flail, 19 patients with structurally normal leaflets and functional regurgitation due to abnormal leaflet coaptation, and 6 patients with rheumatic mitral disease. On both preoperative and intraoperative studies, regurgitation was quantified using maximal jet area and jet diameter at the vena contracta on color flow Doppler. Patients with leaflet flail and patients with functional MR had similar measures of regurgitation severity on preoperative imaging. On intraoperative imaging, regurgitant jet size was unchanged compared with preoperative studies among patients with leaflet flail (jet diameter 1.04 +/- 0.26 vs 1.10 +/- 0.28 cm, area 9.8 +/- 4.5 vs 10.1 +/- 5.2 cm2 on preoperative studies), although jet size decreased significantly in patients with functional MR (jet diameter 0.79 +/- 0.33 vs 1.10 +/- 0.29 cm [p < 0.001], area 5.7 +/- 3.5 vs 10.0 +/- 3.8 cm2 [p < 0.001] on preoperative studies). These findings were not accounted for by variation in heart rate, blood pressures, echocardiographic instrumentation, or Doppler Nyquist limit.(ABSTRACT TRUNCATED AT 250 WORDS)

Pattern of injury and the role of neutrophils in reperfusion injury of rat lung

Using a rat lung model, we sought to characterize the time course for ischemia-reperfusion injury and the role of neutrophils in the development of injury. Adult male Long-Evans rats underwent left thoracotomy with dissection and clamping of the left pulmonary artery, bronchus, and vein for 90 min, resulting in complete left lung ischemia. The lungs were then ventilated and reperfused for up to 4 hr. Time-matched sham animals underwent the identical thoracotomy and hilar dissection, but the lungs were not rendered ischemic. Using vascular permeability of 125I-labeled bovine serum albumin as a measure of reperfusion injury, a bimodal pattern of injury was observed. Compared to sham controls, animals undergoing ischemia-reperfusion demonstrated a significant early phase of lung injury at 30 min of reperfusion (P < 0.0001), followed by partial recovery. A second peak of lung injury was noted after 4 hr of reperfusion (P < 0.001). Myeloperoxidase activity in reperfused lung tissue, a measure of neutrophil sequestration, increased during the reperfusion time course. To determine the role of neutrophils in the development of lung reperfusion injury, additional animals undergoing the identical ischemia-reperfusion protocol received either rabbit anti-rat neutrophil serum or preimmune serum the day prior to operation. Profound neutropenia (< 75/mm3 blood) was confirmed by differential leukocyte counts. Neutropenia had no protective effect against microvascular permeability at 30 min of reperfusion, but there was a significant reduction in lung injury at 4 hr (P < 0.005). We conclude that, during lung ischemia-reperfusion, there is a bimodal pattern of injury, consisting of both neutrophil-independent and neutrophil-mediated events.

Early outcome of mitral valve reconstruction in patients with end-stage cardiomyopathy

Uncontrollable severe mitral regurgitation is a frequent complication of end-stage cardiomyopathy, significantly contributing to heart failure in these patients, and predicts a poor survival. Although elimination of mitral valve regurgitation could be most beneficial in this group, corrective mitral valve surgery has not been routinely undertaken in these very ill patients because of the presumed prohibitive operative mortality. We studied the early outcome of mitral valve reconstruction in 16 consecutive patients with cardiomyopathy and severe, refractory mitral regurgitation operated on between June 1993 and April 1994. There were 11 men and five women, aged 44 to 78 years (64 +/- 8 years) with left ventricular ejection fractions of 9% to 25% (16% +/- 5%). Preoperatively all patients were in New York Heart Association class IV, had severe mitral regurgitation (graded 0 to 4+ according to color flow Doppler transesophageal echocardiography) and two were listed for transplantation. Operatively, a flexible annuloplasty ring was implanted in all patients. Four patients also had single coronary bypass grafting for incidental coronary disease. In four patients the operation was performed through a right thoracotomy because of prior coronary bypass grafting, and four patients also underwent tricuspid valve reconstruction for severe tricuspid regurgitation. No patient required support with an intraaortic balloon pump. There were no operative or hospital deaths and mean hospital stay was 10 days. There were three late deaths at 2, 6, and 7 months after mitral valve reconstruction, and the 1-year actuarial survival has been 75%. At a mean follow-up of 8 months, all remaining patients are in New York Heart Association class I or II, with a mean postoperative ejection fraction of 25% +/- 10%. There have been no hospitalizations for congestive heart failure, and a decrease in medications required has been noted. For patients with cardiomyopathy and severe mitral regurgitation, mitral valve reconstruction as opposed to replacement can be accomplished with low operative and early mortality. Although longer term follow-up is mandatory, mitral valve reconstruction may allow new strategies for patients with end-stage cardiomyopathy and severe mitral regurgitation, yielding improvement in symptomatic status and survival.

Stenosis of the central airways: evaluation by using helical CT with multiplanar reconstructions

PURPOSE

To assess the accuracy of helical computed tomography (CT) with multiplanar reconstructions (MPRs) in the evaluation of stenoses of the central airways.

MATERIALS AND METHODS

Thin-section axial CT and helical CT with MPRs were used to examine the central tracheobronchial tree for the presence of stenosis in 27 patients who underwent lung transplantation and 17 nontransplantation patients. The findings from these modalities were then compared with the findings obtained at conventional tomography and bronchoscopy, when available.

RESULTS

Axial CT alone was 91% accurate in depicting stenosis, CT with MPRs was 94% accurate, and conventional tomography was 89% accurate in the evaluation of bronchial anastomosis in transplant recipients. CT and CT scans with MPRs were each 91% accurate in depicting stenosis in nontransplantation patients; the single false-negative finding showed focal tracheomalacia at bronchoscopy.

CONCLUSION

CT with MPRs may be more accurate than thin-section axial CT in the demonstration of mild stenosis, the length of a stenosis, and horizontal webs.

Retrograde cerebral perfusion during hypothermic circulatory arrest reduces neurologic morbidity

Hypothermic circulatory arrest has become an accepted technique for a variety of cardiac and complex aortic operations. However, prolonged periods (> 45 min) of hypothermic circulatory arrest in older patients is associated with marginal cerebral protection and an increased incidence of adverse neurologic events. In an effort to minimize such morbidity, we used a technique of retrograde cerebral perfusion with continuous monitoring of cerebral hemoglobin oxygen saturation during hypothermic circulatory arrest in 35 patients who underwent thoracic aortic operations or resection of intracardiac tumor. There were 27 men and 8 women (mean age 60 years, range 21 to 83 years). Sixteen patients had acute dissection, 6 had contained rupture of a thoracic aortic aneurysm, 10 had either a chronic dissection or aneurysm, and 3 had hypernephromas extending into the heart. Six patients underwent root replacement by means of an open technique for their distal anastomosis, 7 underwent root and partial arch replacement, 12 had root and total arch replacement, 7 had total arch replacement, and 3 had resection of tumor in the heart and retrohepatic vena cava. Seven patients had simultaneous coronary artery bypass grafting, 3 had replacement of one of the arch vessels, and 2 patients had a cesarean section. Sixteen cases were emergency, 6 urgent, and 13 elective. Nine (26%) were reoperations. Thirty-four patients underwent the procedure via a median sternotomy and one patient through a posterolateral thoracotomy. The mean retrograde cerebral perfusion time was 63 minutes (range 35 to 128 minutes), with 30 (86%) patients having more than 45 minutes, 12 (34%) having more than 65 minutes, and 4 (11%) having more than 90 minutes. There was 1 operative death caused by a preoperative myocardial infarction from an aortic dissection, and there were 2 late deaths (multiple organ failure and ruptured total aortic aneurysm). One patient had a stroke with a residual right hemiplegia and a pronounced aphasia. There were no other significant neurologic events or reoperations for bleeding. The average length of stay for patients having elective operations was 11 days and for those having emergency operations, 27 days. At a mean follow-up of 6 months all surviving patients (91%) are well. Hypothermic circulatory arrest is a relatively simple technique that provides a bloodless field and good visualization without the need for aortic crossclamps. Moreover, retrograde cerebral perfusion with continuous monitoring of cerebral oxygen saturation extends the "safe" time for hypothermic circulatory arrest, allowing ample opportunity to perform complicated cardiac and aortic operations with reduced risk of adverse neurologic events.

Cardiopulmonary exercise testing following allogeneic lung transplantation for different underlying disease states

OBJECTIVES

To assess the exercise response to single lung transplantation in chronic airflow obstruction (CAO), idiopathic pulmonary fibrosis (IPF), and pulmonary vascular disease (PVD) vs double lung transplantation at well-defined time points after transplantation, and to define the change in exercise response in SLT and DLT over the first year after transplantation.

DESIGN

Prospective study.

SETTING

Tertiary referral hospital.

PATIENTS

Fourteen stable SLT recipients (6 with CAO, 4 with IPF, 4 with PVD) and 11 stable DLT recipients.

MEASUREMENTS

Spirometry, lung volumes, diffusion lung capacity for carbon monoxide (DLco) and MVV measured prior to exercise at 3 months (n = 25) then at 3-month intervals up to a maximum of 12 months post-transplantation (n = 18 [12 SLT and 6 DLT]). Symptom-limited cardiopulmonary exercise tests at same time points (n = 25 at 3 months, n = 18 [12 SLT and 6 DLT] at 3-month intervals up to 12 months). Breathlessness was estimated by visual analogue scale prior to exercise and at peak exercise.

RESULTS

At 3 months, FEV1 percent predicted was lower for SLT-CAO and SLT-IPF vs DLT (p < or = 0.05). Mean FEV1/FVC was lower for SLT-CAO vs all other groups (p < or = 0.05). The FVC, MVV, and DLco/VA were similar for all groups. The TLC and RV were higher for the SLT-CAO group compared with all others. The TLC was lower for SLT-PVD compared with DLT. Exercise responses were similar in all groups studied without a statistically significant difference in achieved VO2, work rate, O2 pulse, anaerobic threshold, heart rate response, respiratory rate, VE/MVV, and VT/VC. The change in O2 saturation during exercise was the least in recipients of DLT. Maximal achieved VO2 rose from 3 to 6 months after SLT but dropped by 9 to 12 months after transplantation. Maximal achieved VO2 trended up from 3 to 6 months after DLT but dropped by 9 to 12 months after transplantation. Maximal achieved work rate rose in both SLT and DLT from 3 to 9 to 12 months after transplantation. There was no significant difference in breathlessness at rest and peak exercise measured between recipients of SLT or DLT.

CONCLUSIONS

Minor differences in pulmonary function and change in O2 saturation occur between recipients of SLT and DLT during the first posttransplant year. These differences are most pronounced when comparing SLT-CAO with DLT. However, there is no significant difference in exercise capacity between SLT for CAO, IPF, PVD, and DLT. The rise in maximum achieved VO2 over the first 6 months after transplantation may reflect the effects of exercise training and should be taken into account when examining aerobic response after transplantation.

Aortobronchial fistula 13 years following repair of aortic transection

We describe a 56-year-old man with the new onset of hemoptysis, increasing in frequency and magnitude, initially diagnosed and treated as pulmonary embolism. Bronchoscopy, computed tomography, and thoracic aortography were performed twice before the diagnosis was made. Thirteen years previously, the patient underwent thoracic aortic interposition graft placement for aortic laceration as a result of a motor vehicle accident. The second aortogram demonstrated a small pseudoaneurysm at the expected proximal graft suture line. Aortobronchial fistula, a rare cause of hemoptysis, was diagnosed. The patient underwent successful resection of the graft and placement of a new dacron interposition graft. All cultures, including blood, sputum, and operative specimen cultures, were negative. The patient is alive and well 1 year following surgery.