Cerebral microembolization after bioprosthetic aortic valve replacement: comparison of warfarin plus aspirin versus aspirin only

BACKGROUND

No human physiological data exists on whether aspirin only is as effective as warfarin plus aspirin in preventing cerebral microembolization in the early postoperative period after bioprosthetic aortic valve replacement (bAVR).

METHODS AND RESULTS

We prospectively enrolled 56 patients who had no other indication for oral anticoagulation, who underwent bAVR and received, in an open-label fashion, either daily warfarin (for INR 2.0-3.0) plus 81 mg of aspirin (n=28) or 325 mg of aspirin only (n=28). Cerebral microembolization was quantified at 4 hours (baseline) and at 1 month postoperatively, by recording 1-hour bilateral middle cerebral artery (MCA) microembolic signals (MES). Platelet-function analysis (PFA) of closure times (CT) on collagen was also used as a marker of platelet-dependent activation. Follow-up to 1 year was complete. Preoperative demographics and baseline platelet function were equivalent in both groups. There was no mortality, stroke, or transient ischemic attack at 1 year in either group. No significant differences were found in the proportion of patients with MES among those receiving warfarin plus aspirin versus aspirin only, at baseline (68% versus 82%, respectively; P=0.4) and at 1 month (46% versus 43%; P=1.0) after bAVR. The total MES and PFA were also equivalent between groups, at baseline and follow-up.

CONCLUSIONS

Early after bAVR, the effects of these 2 antithrombotic regimens on cerebral microembolization and platelet function are equivalent. These data bring new mechanistic support to the premise that aspirin only may safely be used early after bAVR in patients who have no other indication for oral anticoagulation.

Left ventricular outflow tract-right atrial fistula following aortic valve replacement

A 59-year-old male, undergoing outpatient treatment of a sternal wound infection following elective aortic valve replacement surgery, presented with decompensated heart failure. The patient required emergency redo surgery after investigations revealed a left ventricular outflow tract to right atrial fistula due to endocarditis with right ventricular dysfunction. Echocardiography, in particular transesophageal echocardiography, was essential for the diagnosis of this rare event.

Characterization of mitral valve prolapse with cardiac computed tomography: comparison to echocardiographic and intraoperative findings

A single imaging modality that can accurately assess both coronary anatomy and mitral valve (MV) anatomy prior to surgery may be desirable. We sought to determine the diagnostic accuracy of cardiac computed tomography (CT) to detect and characterize mitral valve prolapse (MVP) compared to echocardiography. Consecutive patients referred for 'single-source' cardiac CT for investigation prior to non-coronary cardiac sugery were identified. MV anatomy was assessed for MVP and results were compared to echocardiography and to intra-operative visual assessment of the MV. Comparison between the three modalities was performed at the per-patient, per-leaflet and per-scallop levels. A total of 67 consecutive patients that were referred for Cardiac CT prior to non-coronary cardiac surgery and were prospectively recruited into a Cardiac CT registry. Of these, 65 patients underwent cardiac surgery. 63 patients had echocardiography and 32 patients had intra-operative visual assessment of the mitral valve. Compared to echocardiography, cardiac CT had excellent sensitivity (92.6%) and specificity (97.1%) for the detection of any MVP, but had poor sensitivity (68.5%) for the detection of individual prolapsing scallop. Compared to intra-operative visual assessment of the prolapsing scallop, both cardiac CT and echocardiography had low sensitivity (58.1 and 78.1%, respectively). Cardiac CT was able to identify patients with MVP but had difficulty identifying the prolapsed scallops compared to echocardiography. Single-source CT may not be ready for characterization of individual mitral valve scallops.

Apico-Aortic Conduit for severe aortic stenosis: Technique, applications, and systematic review

Patients referred for aortic valve replacement are often elderly and may have increased surgical risk associated with ascending aortic calcification, left ventricular dysfunction, presence of coronary artery disease, previous surgery, and/or presence of several co-morbidities. Some of these patients may not be considered candidates for conventional surgery because of their high risk profile. While transcatheter aortic valve replacement constitutes a widely accepted alternative, some patients may not be eligible for this modality due to anatomic factors. Apico-Aortic Conduit (AAC) insertion (aortic valve bypass surgery) constitutes a possible option in those patients. Apico-Aortic Conduit is not a new technique, as it has been used for decades in both pediatric and adult populations. However, there is a resurging interest in this technique due to the expanding scope of elderly patients being considered for the treatment of aortic stenosis. Herein, we describe our surgical technique and provide a systematic review of recent publications on AAC insertion, reporting that there is continued use and several modifications of this technique, such as performing it through a small thoracotomy without the use of the cardiopulmonary bypass.

Effects of mitral valve surgery on myocardial energetics in patients with severe mitral regurgitation

BACKGROUND

Hemodynamically significant mitral regurgitation (MR) may alter left ventricular (LV) myocardial energy requirements. The effects of MR and subsequent corrective mitral valve (MV) surgery on myocardial energetics are not well understood. A better understanding of myocardial energetics and the LV responses to changes in preload and afterload may assist with the understanding of mitral regurgitation and its effect on the LV. We sought to determine the effects of MV surgery on forward stroke work, myocardial oxidative metabolism, and myocardial efficiency.

METHODS AND RESULTS

Prospectively enrolled patients with chronic, severe, nonischemic mitral regurgitation underwent echocardiography, radionuclide angiography, and C-11 acetate positron emission tomography to measure LV volumes, ejection fraction, and oxidative metabolism before and 1 year after MV surgery. Forward and total stroke work corrected for oxidative metabolism was used to estimate efficiency using the work metabolic index. Fourteen patients (age, 59+/- 8 years) with myxomatous MV were enrolled. One year after MV surgery, there was a reduction in LV end-diastolic and end-systolic volumes (231+/-86 to 131+/-21 mL; P<0.01 and 98+/-53 to 55+/-17 mL; P<0.01). Forward stroke volume increased (58.1+/-15.0 to 75.5+/-23 mL; P<0.01), LV ejection fraction was preserved without a significant change in oxidative metabolism. Forward work metabolic index improved (4.99+/-1.32 x 10(6) to 6.59+/-2.45 x 10(6) mm Hg x mL/m(2); P=0.02). This was not at the expense of total work metabolic index, which was preserved.

CONCLUSIONS

MV surgery has a beneficial effect on forward stroke volume and forward work metabolic index without adverse effects on oxidative metabolism or total work metabolic index.

Cardiac bioassist: results of the French multicenter cardiomyoplasty study

The French multicenter experience (6 centers) of dynamic cardiomyoplasty was analyzed for long-term survival and functional outcome, the most important endpoints in congestive heart failure therapy. Cardiomyoplasty was performed in 212 patients with symptoms of chronic heart failure despite maximal pharmacological therapy. The etiology was ischemic (48%), idiopathic (45%) or other (7%). Cardiomyoplasty was performed using the latissimus dorsi muscle which was electrostimulated after surgery. During follow-up, 88% of patients improved clinically. Hospital death occurred in 29 (14%) patients and was related to the severity of preoperative heart failure symptoms. Late mortality occurred in 99 patients due to heart failure (44%), sudden death (37%), or noncardiac causes (18%). Combined dynamic cardiomyoplasty and implantation of a cardiac rhythm management system was safely achieved in 22 patients, and 26 underwent heart transplantation for recurrent heart failure. Long-term functional improvements were observed in most patients, and the best outcome was achieved in those with isolated right ventricular failure. Dynamic cardiomyoplasty can be considered as a destination therapy or a mid- to long-term biological bridge to heart transplantation.

Using technology to create a medication safety net for cardiac surgery patients: a nurse-led randomized control trial

PURPOSE

Interactive voice response (IVR) technology was used to increase medication compliance and reduce adverse events (hospitalization and emergency visits) in post-cardiac surgery patients.

METHOD

Patients randomized to intervention received 11 automated IVR calls in the six months after discharge. A total of 331 patients (164 IVR, 167 usual care) participated.

RESULTS

Findings showed significant differences in the IVR group for the primary composite outcome of compliance and adverse events (relative risk (RR] and 95% confidence interval [CI]: 0.60 [0.37, 0.96), p = 0.041) and the secondary outcome of medication compliance (RR: 0.34 (0.20, 0.56), p < 0.0001). There was no significant impact on emergency room visits (RR: 1.04 (0.63, 1.73J) and hospitalization (RR: 0.77 [0.41, 1.45]). Most patients (93%) preferred IVR follow-up to no follow-up.

A method to distinguish between gaseous and solid cerebral emboli in patients with prosthetic heart valves

BACKGROUND

The difficulty of distinguishing solid from air emboli using transcranial Doppler has limited its use in situations where both types of emboli can occur, such as in mechanical heart valve patients. To make transcranial Doppler clinically useful, a method must be found to distinguish benign air bubbles from the more damaging solid particulates. Since inhalation of 100% oxygen reduces the amount of air bubbles in mechanical heart valve patients, the ultrasonic features of the remaining emboli would be characteristic of solid particulates.

OBJECTIVE

We determined the accuracy of the signal relative intensity measured with transcranial Doppler to distinguish between gaseous and non-gaseous emboli in mechanical heart valve patients examined during room air and 100% oxygen. Embolic signals detected in patients with bioprosthetic valves examined during 100% oxygen comprised the source of solid particulates.

METHODS

Embolic signals were detected during room air (n=141) and 100% oxygen (n=45) from 17 mechanical valve patients at two Doppler examinations (4h and 4 days after surgery). Solid embolic signals (n=31) from seven patients with bioprosthetic valves were identified with 100% oxygen within the first 4h after surgery. Frequency plots and receiver operating characteristic curves assessed signal intensity differences between mechanical and bioprosthetic valve groups during 100% oxygen and the efficacy of the relative intensity for differentiating gaseous from solid emboli.

RESULTS

Administration of 100% oxygen during transcranial Doppler examination in mechanical heart valve patients decreased the count of embolic signals compared with room air (p=0.006). The embolic signals of mechanical heart valve patients breathing 100% oxygen showed lower relative intensities compared with those during room air. The distribution of the signal relative intensity between mechanical and bioprosthetic valve groups during 100% oxygen was similar. A 16dB cut-off threshold achieved the best accuracy for differentiating non-gaseous from gaseous emboli (sensitivity: 60%; specificity: 82%; area: 0.721; p<0.0001).

CONCLUSIONS

The use of a signal intensity cut-off offers adequate discrimination of the embolic composition in mechanical heart valve patients. Future studies evaluating prophylactic treatments of thrombosis in these patients should assess the predictive value of this intensity threshold and their potential association with outcome indicators and procoagulant markers.

Gender-specific differences in aortic sinus curvature during aging: an anatomical and computational study

INTRODUCTION

Our goal was to investigate the potential impact of aortic sinus wall curvature on the risk for type A aortic dissection.

METHODS

We measured the curvature and carried out histological tests of the aortic noncoronary sinus in 46 patients who did not die from cardiac disease. Based on observed curvature values, we investigated the mechanical stress in the aortic root using finite element analysis.

RESULTS

Sinus curvature was found to experience a more than fourfold increase with age in males and reached the higher, age-independent values measured in females by age 65. The histological tests revealed that degenerative alterations did not significantly increase with aging in either gender, although fibrosis did in older women. Finite element analysis illustrated that the risk for a circumferential tear to occur was smallest when sinus curvature was highest.

CONCLUSIONS

We established significant gender-specific disparities in the aortic root during aging: while aortic sinus curvature was high in females throughout their lives, it experienced a more than fourfold increase in the lifetime of males, matching values in females only by age 65. Our mechanical analyses confirmed the overall potential protective role of higher sinus wall curvature with respect to type A aortic dissection, and geometry alone could not account for the known gender difference in aortic dissection prevalence.

Assessment of cyclosporine pharmacokinetic parameters to facilitate conversion from C0 to C2 monitoring in heart transplant recipients

BACKGROUND

Cyclosporine (CsA) 2-hour postdose (C2) monitoring is recommended to assess CsA exposure and predict clinical outcomes among heart transplant recipients. We correlated pharmacokinetic parameters and clinical outcomes in stable long-term heart transplant recipients monitored with C0 to develop an algorithm to convert patients from C0 to C2 monitoring.

METHODS

Paired CsA C0-C2 measurements and serum creatinine levels were obtained from 35 heart transplant recipients more than 2 years posttransplantation (mean 8.8+/-4.7 years).

RESULTS

The mean CsA dose and C0, C2, and C0/C2 ratio were 85+/-23 mg/12 hours, 123+/-41 ng/mL, 572+/-274 ng/mL and 4.8+/-2.1, respectively. C0 correlated weakly with C2 (r=.42, P=.011). The CsA dose correlated better with C2 (r=.58; P<.001) than with C0 (r=.37; P=.026). A good correlation was noted between C2 and the C2/C0 ratio (r=.73; P<.001), but none between C0 and the C2/C0 ratio. A borderline significant inverse correlation was noted between C0 and the worst endomyocardial biopsy score (r=-.34; P=.045), whereas none was noted with C2. Serum creatinine level did not correlate with either C2 or C0. Among patients with C0 within our target of 100 to 150 ug/L, six had C2 above 300 to 600 ug/L as suggested by the literature.

CONCLUSIONS

In long-term heart transplant recipients, we could not identify a single pharmacokinetic parameter that could be used to develop an algorithm to convert from C0 to C2 monitoring; however, C2 may be better than C0 for identifying patients at risk of overexposure to CsA.

Transcranial Doppler and acoustic pressure fluctuations for the assessment of cavitation and thromboembolism in patients with mechanical heart valves

The formation and collapse of vapor-filled bubbles near a mechanical heart valve is called cavitation. Such microbubbles are suspected to have strong pro-coagulant effects. Therefore, cavitation may be a contributing factor to the pro-thrombotic effects of mechanical valves. Herein, we systematically review the available evidence linking cavitation and thrombosis. We also critically appraise the potential usefulness of transcranial Doppler and other new non-invasive diagnostic methods to study cavitation and cerebral embolism in mechanical valve patients. Experimental studies indicate that cavitation microbubbles cause platelet aggregation, complement-activation, fibrinolysis, release of tissue-factor, and endothelial damage. Administration of 100% oxygen to mechanical valve patients during transcranial Doppler examination can transiently decrease the counts of Doppler-detected cerebral microemboli compared with room air. This is associated with removal of most circulating gaseous emboli from cavitation. This method may therefore be applied to the study of cavitation and thromboembolism. Additionally, the analysis of high-frequency acoustic-pressure fluctuations detected from the implosion of cavitation bubbles is a promising method for assessment of cavitation in vivo; however, this requires further development. A better understanding of cavitation is important in order to adequately investigate its role in the overall pro-thrombotic effects in mechanical valve patients. Such studies may allow establishing guidelines for new valve designs.

Surgical treatment of active aortic endocarditis: homografts are not the cornerstone of outcome

BACKGROUND

Surgical treatment of active aortic infective endocarditis is challenging, and the type of prosthesis to be implanted during the active phase remains controversial.

METHODS

All consecutive patients with definite diagnosis of aortic infective endocarditis operated on during the active phase were included. Endpoints were in-hospital mortality and a combined endpoint including infective endocarditis recurrence, prostheses dysfunction, or long-term cardiovascular mortality.

RESULTS

Among 127 consecutive patients, mean age 57 +/- 15 years, 87% male, 30% with preexisting aortic prosthesis, and 63 (50%) with annulus abscess, 54 (43%) were treated with aortic homograft and 73 (57%) with conventional prosthesis. Median time between diagnosis and surgery was 10 days. In-hospital mortality was 9%, not different between homograft and conventional prostheses (11% versus 8%, p[ = 0.6). By multivariable analysis, prosthetic valve endocarditis (8.5 95% confidence interval: 2.2 to 33.6, ]p = 0.001) was the only variable independently associated with in-hospital mortality, which was not influenced by type valvular substitute (p = 0.6), even in the subset with annulus abscess (p = 0.2). Ten-year survival free from the combined endpoint was 44% +/- 10%, not different between homograft and conventional prostheses (log rank p = 0.2). By multivariable analysis, comorbidity index (2.6 [1.05 to 6.3], p = 0.04) and prosthetic valve endocarditis (2.3 [1.2 to 4.6], p = 0.02) were independently predictive of the combined endpoint, which was not determined by type of valvular substitute (p = 0.6) even in the subset with annulus abscess (p = 0.5).

CONCLUSIONS

Implantation of conventional prostheses during the active phase of aortic endocarditis yields similar low operative mortality and long-term prognosis as compared with aortic homografts, even in patients with annulus abscess.

The Cardiotomy Trial

Background— Reinfusion of unprocessed cardiotomy blood during cardiac surgery can introduce particulate material into the cardiopulmonary bypass circuit, which may contribute to postoperative cognitive dysfunction. On the other hand, processing of this blood by centrifugation and filtration removes coagulation factors and may potentially contribute to coagulopathy. We sought to evaluate the effects of cardiotomy blood processing on blood product use and neurocognitive functioning after cardiac surgery.

Methods and Results— Patients undergoing coronary and/or aortic valve surgery using cardiopulmonary bypass were randomized to receive unprocessed blood (control, n=134) or cardiotomy blood that had been processed by centrifugal washing and lipid filtration (treatment, n=132). Patients and treating physicians were blinded to treatment assignment. A strict transfusion protocol was followed. Blood transfusion data were analyzed using Poisson regression models. The treatment group received more intraoperative red blood cell transfusions (0.23±0.69 U versus 0.08±0.34 U, P =0.004). Both red blood cell and nonred blood cell blood product use was greater in the treatment group and postoperative bleeding was greater in the treatment group. Patients were monitored intraoperatively by transcranial Doppler and they underwent neuropsychometric testing before surgery and at 5 days and 3 months after surgery. There was no difference in the incidence of postoperative cognitive dysfunction in the 2 groups (relative risk: 1.16, 95% CI: 0.86 to 1.57 at 5 days postoperatively; relative risk: 1.05, 95% CI: 0.58 to 1.90 at 3 months). There was no difference in the quality of life nor was there a difference in the number of emboli detected in the 2 groups.

Conclusions— Contrary to expectations, processing of cardiotomy blood before reinfusion results in greater blood product use with greater postoperative bleeding in patients undergoing cardiac surgery. There is no clinical evidence of any neurologic benefit with this approach in terms of postoperative cognitive function.

Distinguishing air from solid emboli using ultrasound: in-vitro study of the effect of Doppler carrier frequency

OBJECTIVE

To compare the ability of the signal relative-intensity and sample-volume-length (SVL) to discriminate air bubbles from solid spheres in an in-vitro model using two different carrier frequencies of the Doppler transducer.

METHODS

A gel ultrasound phantom was connected to a circuit in which blood-mimicking fluid circulated. Air bubbles (100-140 microm) and latex spheres (125 +/- 10 microm) were injected into the circuit and interrogated using 1- and 2-MHz transducers. High-intensity-transient-signals (HITS) were recorded with a dual-gated transcranial Doppler (TCD) system. Receiver-Operating-Characteristic curves determined the best cut-off points that would distinguish between embolic materials.

RESULTS

HITS from air bubbles had higher intensities and longer SVL than solid spheres with either transducer (P < .0001). Air bubbles (P < .0001) and microspheres (P= .049) showed higher intensities with the 1-MHz relative to the 2-MHz transducer. The intensity increase with the 1-MHz transducer was greater for air bubbles than microspheres (P < .0001). The discriminating efficacy of both the relative-intensity and SVL was similar between transducers (intensity, P= .201; SVL, P= .98).

CONCLUSIONS

The relative-intensity and SVL are equally effective to distinguish solid from air emboli using 1- and 2-MHz transducers. Our study indicates that using a lower carrier frequency does not improve the discrimination of air from solid emboli.

The impact of patient–prosthesis mismatch on late outcomes after mitral valve replacement

OBJECTIVES

The incidence of patient-prosthesis mismatch after mitral valve replacement and its effect on late outcomes have remained unclear. This study was conducted to determine the impact of patient-prosthesis mismatch on recurrent congestive heart failure, postoperative pulmonary hypertension, and late survival after mitral valve replacement.

METHODS

Between 1985 and 2005, 884 patients, with a mean age 63 +/- 12 years, underwent mitral valve replacement (657 mechanical, 227 bioprosthesis) with contemporary prostheses. Mean clinical and echocardiographic follow-up was 5.1 +/- 4.1 years (4344 patient-years). Patient-prosthesis mismatch was defined as an indexed effective orifice area of 1.25 cm2/m2 or less. Parametric and nonparametric analyses were used to determine predictors of outcomes.

RESULTS

The incidence of patient-prosthesis mismatch was 32%. Predictors of recurrent congestive heart failure included low indexed effective orifice area, low ejection fraction, elevated postoperative mean mitral gradient, and use of a bioprosthesis (P < or = .05). Postoperative pulmonary hypertension was associated with small mitral size, elevated mean mitral gradient, low ejection fraction, and atrial fibrillation (P < or = .05); indexed effective orifice area did not predict postoperative pulmonary hypertension (P = .89). Poor late survival was predicted by low indexed effective orifice area (< or =1.25 cm2/m2), New York Heart Association class 3 or 4, elevated right ventricular pressure, stroke, older age, coronary artery disease, and bioprosthesis use (P < or = .05). Survival for patients with patient-prosthesis mismatch versus those without patient-prosthesis mismatch at 1, 3, 5, and 10 years was 91% versus 95%, 85% versus 90%, 78% versus 86%, and 65% versus 75%, respectively (P = .05).

CONCLUSIONS

Patient-prosthesis mismatch after mitral valve replacement is not uncommon; it is associated with recurrence of congestive heart failure and postoperative pulmonary hypertension and independently affected late survival. This study emphasizes the importance of implanting a sufficiently large prosthesis in adult patients undergoing mitral valve replacement.

Management of acute severe perioperative failure of cardiac allografts: a single-centre experience with a review of the literature

BACKGROUND

Early graft failure is associated with high mortality and is the main cause of death within the first 30 days after transplantation. The purpose of the present study was to examine the investigators' experience of severe perioperative acute graft failure and to review the literature.

METHODS

Nine of 385 cardiac transplants (2.3%) performed from 1984 through 2005 developed severe perioperative acute graft failure either in the operating room or within 24 h after cardiac transplantation. Four patients had primary graft failure, two had right heart failure secondary to pulmonary hypertension, one had hyperacute rejection, one had accelerated acute rejection and one possibly sustained a particulate coronary embolus intraoperatively.

RESULTS

All except the two patients who had right heart failure secondary to pulmonary hypertension received mechanical circulatory support. Three patients were supported with total artificial hearts, two patients received a left ventricular assist device, one patient was supported with extracorporeal life support followed by a right ventricular assist device when the left ventricle recovered, and one patient was supported for several hours with cardiopulmonary bypass. Three patients were retransplanted after mechanical circulatory support, but only one survived. Only one of the nine patients (11%) survived; this patient was supported with a total artificial heart followed by retransplantation.

CONCLUSION

The outcome of severe perioperative acute graft failure is very poor. Mechanical circulatory support and retransplantation are not as successful as in other situations. Due to the shortage of donors and poor outcomes, retransplantation for hyperacute rejection is not advisable.

Surgery for chronic thromboembolic pulmonary hypertension--inclusive experience from a national referral center

BACKGROUND

Chronic thromboembolic pulmonary hypertension represents a unique form of pulmonary hypertension amenable to curative intervention with a pulmonary thromboendarterectomy (PTE). Canada's first successful and sustainable program for PTE surgery was established at the University of Ottawa Heart Institute in 1995. Inclusive results from similarly sized programs are not readily available owing to selective reporting, therefore making it difficult to benchmark outcomes. The purpose of this report is to provide a review of the inclusive results from our moderately sized national program for all PTE, with a particular emphasize on the aspects of the learning curve in terms of patient management.

METHODS

Since 1995, 180 patients have been referred for consideration of PTE, and 106 patients have undergone surgery with a perioperative 30-day mortality rate of 9.4%.

RESULTS

There was a significant improvement in all hemodynamic parameters except right ventricular ejection fraction in nonsurvivors (mean pulmonary artery pressure pre 47 +/- 12 mm Hg versus post 28 +/- 9 mm Hg, p < 0.0001; pulmonary vascular resistance pre 814 +/- 429 dynes x sec(-1) x cm(-5), post 224 +/- 145 dynes x sec(-1) x cm(-5), p < 0.0001; cardiac index pre 2.0 +/- 0.7 L x min(-1) x m(-2), post 3.2 +/- 0.7 L x min(-1) x m(-2), p < 0.0001). A postoperative pulmonary vascular resistance of 500 dynes x sec(-1) x cm(-5) or more was associated with increased perioperative mortality (odds ratio, 12 +/- 8.7; p = 0.001). On average, these procedures were associated with significant resource use involving operating room time (610 +/- 243 minutes), intensive care unit and hospital days (11.2 +/- 13.7 and 19.5 +/- 15.6 days), and ventilation time (7.8 +/- 10.0 days). There was no significant change in hospital or intensive care unit length of stay, or the mortality rate during this first decade.

CONCLUSIONS

PTE programs are resource-intensive surgical specialty services that demand excellence in cardiothoracic expertise. The initial decade reflected an expanding referral basis and likely parallel increases in patient complexity and expertise. The current results at a national referral center have emphasized the importance of centralization of resources to optimize patient outcome.

Delayed thrombin generation is not associated with fibrinopeptide formation during prolonged cardiopulmonary bypass with hirudin anticoagulation

Patients with heparin-induced thrombocytopenia urgently requiring surgery with cardiopulmonary bypass (CPB) present a unique management challenge that must be addressed by the use of alternative anticoagulants. Although clinical success with the direct thrombin inhibitor hirudin has been reported, there is sparse information in the literature supporting the efficacy of this drug as an anti-thrombotic to prevent fibrin formation during CPB. In this report, we describe the efficacy of this drug to prevent thrombin-mediated fibrin formation during CPB.

Using personal digital assistants and patient care algorithms to improve access to cardiac care best practices

In order to facilitate knowledge transfer between specialists and generalists and between experts and novices, and to promote interdisciplinary communication, there is a need to provide methods and tools for doing so. This interdisciplinary research team developed and evaluated a decision support tool (DST) on a personal digital assistant (PDA) for cardiac tele-triage/tele-consultation when the presenting problem was chest pain. The combined human factors methods of cognitive work analysis during the requirements-gathering phase and ecological interface design during the design phase were used to develop the DST. A pilot clinical trial was conducted at a quaternary cardiac care hospital over a 3-month period. During this time, the DST was used by the nine nursing coordinators who provide tele-triage/tele-consultation 24/7. This clinical trial validated the design and demonstrated its usefulness to advanced cardiac care nurses, its potential for use by nurses less experienced in cardiac care, and for its potential use in an interdisciplinary team environment.

Sevoflurane Alters Right Ventricular Performance But Not Pulmonary Vascular Resistance in Acutely Instrumented Anesthetized Pigs

OBJECTIVE

Although the effects of halogenated agents on both normal and diseased left ventricles have been widely studied, the influence of these anesthetic agents on right ventricular (RV) performance remains less well characterized. This study was undertaken to examine the effects of 2 different concentrations of sevoflurane on RV function, and coronary and pulmonary hemodynamics in acutely instrumented anesthetized pigs.

DESIGN

Prospective experimental study.

SETTING

Laboratory of experimental research in a university teaching hospital.

SUBJECTS

Anesthetized pigs.

INTERVENTIONS

Regional RV function in 10 pigs was determined from pressure segment length loop analysis, global RV function from stroke work versus end-diastolic pressure relation, right coronary blood flow, and pulmonary vascular resistance (PVR), without and then with 2.6% (minimum alveolar concentration [MAC]) and 3.9 % (1.5 MAC) end-tidal sevoflurane concentrations.

MAIN RESULTS

Sevoflurane preserved inflow systolic shortening and RV regional external work, but significantly depressed outflow systolic shortening (p < 0.05). Global RV stroke work was depressed to 72% +/- 12% and 61% +/- 10% of baseline value, respectively, with 1 and 1.5 MAC of sevoflurane (p < 0.05), but without alteration of PVR. Right coronary blood flow decreased dose dependently.

CONCLUSIONS

Sevoflurane causes significant depression of global RV function associated with a qualitatively different effect on inflow and outflow tracts, without any modification of PVR.

[Adult apico-aortic shunts. A case followed for 6 years]

An apico-aortic shunt enables a reduction in the aortic transvalvular pressure gradient. It is recommended for patients with symptomatic severe stenosis when anatomical constraints contra-indicate valvular replacement. The authors report the case of a patient who underwent this uncommon procedure, which was indicated due to previous coronary bypass surgery using both mammary arteries, plus massive calcification of the ascending aorta. Angio-haemodynamic investigation and MRI performed three years and five years respectively following the procedure confirmed its efficiency. An analysis of the few reported series confirms the value of this special procedure.

Clinical outcomes with the Hancock II bioprosthetic valve

BACKGROUND

The Hancock II bioprosthetic valve, which was first introduced to clinical use in 1978, differs from its predecessor in several ways. This study was designed to evaluate the durability and outcomes with this valve in patients who had isolated aortic or mitral valve replacements.

METHODS

From 1991 to 1999, 459 patients underwent aortic valve replacement and 138 patients underwent mitral valve replacement with the Hancock II bioprosthesis (Medtronic Inc, Minneapolis, MN). The mean age was 73.2 +/- 0.4 and 72.6 +/- 0.8 years in the aortic and mitral groups, respectively. Most patients were in New York Heart Association Class III or IV (50% aortic group and 69% mitral group) and concomitant coronary artery bypass was performed in 49.4% and 52.8% of patients, respectively. Patients were assessed annually and follow-up was up to 129 months in the aortic group and 100 months in the mitral group.

RESULTS

At 8 years, actuarial survival was 52% +/- 5% in the aortic group and 57% +/- 8% in the mitral group. Furthermore, the actuarial freedom from structural failure necessitating reoperation was 99% +/- 0.5% in the aortic group and 98% +/- 2% in the mitral group, and the actuarial freedom from repeat valve surgery due to all causes was 97% +/- 2% and 96% +/- 2%, respectively. Actuarial freedom from thromboembolic events was 89% +/- 2% in the aortic group and 90% +/- 5% in the mitral group.

CONCLUSIONS

The Hancock II valve has excellent midterm durability and clinical performance in older patients.

Left Ventricular Assist Devices as Bridge to Heart Transplantation in Congestive Heart Failure with Pulmonary Hypertension

Severe pulmonary hypertension (PH) has been considered a significant contraindication to cardiac transplantation. Ongoing clinical experience, however, has shown that temporary support using left ventricular assist devices (LVADs) in these patients can result in significant reductions in PH. A comprehensive review of the available literature regarding the use of LVADs in heart failure patients with PH was conducted. The existing literature to date supports the use of LVADs in heart failure patients with PH and demonstrates that significant reductions in PH in these patients can be achieved. This subsequently allows for safe and effective cardiac transplantation in patients who were previously excluded from this modality. For heart failure patients with severe PH, the use of LVADs can provide significant benefits by significantly reducing PH and allowing subsequent staged transplantation.

A Technique for Annular Plication to Facilitate Sliding Plasty After Extensive Mitral Valve Posterior Leaflet Resection

The sliding leaflet technique has been used in mitral valve repair in conjunction with posterior leaflet quadrangular resection to avoid left ventricular outflow tract obstruction secondary to systolic anterior motion of the anterior leaflet of the mitral valve. On occasion, despite the use of the sliding leaflet technique, reattachment of the edges of the posterior leaflet after extensive resection can be challenging because of excessive tension. My colleagues and I present our technique to ensure reattachment of the posterior leaflet without tension after extensive resection.

Effects of Methylprednisolone and a Biocompatible Copolymer Circuit on Blood Activation During Cardiopulmonary Bypass

BACKGROUND

Cardiopulmonary bypass (CPB) induces derangements in physiology characterized by activation of blood pathways that may contribute to multiorgan dysfunction. This trial addresses the efficacy of a biocompatible surface alone and in combination with steroids in inhibiting these changes.

METHODS

In a factorial design, patients undergoing coronary artery bypass grafting were randomized (four groups; n = 17 per group) to CPB utilizing control circuits or a circuit prepared with a surface modifying active copolymer (SMA-CPB), with or without methylprednisolone (MPSS, 1 g intravenous). Leukocyte and complement activation, cytokine release, and bradykinin generation were measured. Clinical outcomes (blood loss, transfusion, arterial pressure response, and postoperative cardiac and pulmonary functions) were also examined.

RESULTS

The SMA-CPB was associated with a significant inhibition of elastase release (p = 0.026) and bradykinin generation (p = 0.027) during CPB. Terminal complement complex (TCC) generation was inhibited as an effect of SMA-CPB (p = 0.047). There was an interaction of SMA-CPB and MPSS to decrease both TCC (p = 0.042) and bradykinin generation (p = 0.028). There were strong effects of MPSS in inhibiting release of interleukin 6 (IL-6) (p = 0.007) and IL-8 (p < 0.001) and tissue plasminogen activator over time (p = 0.009) as well as decreasing peak day 1 creatine kinase (CK, p = 0.015) levels. Clinical effects of MPSS included decreased atrial fibrillation (p = 0.02), improved cardiac index over time, increased pulmonary compliance, and increased insulin need.

CONCLUSIONS

This trial suggests a potential beneficial effect for combined strategies to minimize inflammation after CPB. The specific effect of MPSS in decreasing postoperative atrial fibrillation and CK warrants further investigation of its role as a potential myocardial protective agent.

Delayed Thrombin Generation With Hirudin Anticoagulation During Prolonged Cardiopulmonary Bypass

Patients with heparin-induced thrombocytopenia requiring urgent cardiac surgery present a unique challenge that must be addressed by the use of nonheparin alternatives for anticoagulation during cardiopulmonary bypass. Although isolated cases have been presented involving the use of antithrombin III independent thrombin inhibitor hirudin in this situation, its ability to completely inhibit thrombin activity has not been demonstrated. In this report we describe the efficacy of this drug in inhibiting thrombin during a case requiring prolonged cardiopulmonary bypass.

Left ventricular assist devices for the treatment of congestive heart failure

The mainstay of heart failure therapy is aggressive medical management with consideration of resynchronization therapy and automatic implantable cardioverter-defibrillator. This is best done with the support of a multidisciplinary team. Transplantation, when possible, remains the therapy of choice for patients who are refractory to medical therapy. Other options short of left ventricular assist device (LVAD) that should be considered include revascularization, mitral valve repair, and left ventricular remodeling procedures. LVAD therapy as a bridge to transplantation should be considered in patients with heart failure who are clinically deteriorating while on the transplant waiting list. This should be initiated prior to the onset of irreversible end-organ damage. In nontransplant candidates, an LVAD can be considered as an alternative to transplantation (destination therapy). However, cost and the availability of expertise continue to limit this therapy to quaternary care and research institutions.