Usefulness of routine epicardial pacing wire culture for early prediction of poststernotomy mediastinitis

Poststernotomy mediastinitis (PSM) is one of the most serious complications of cardiac surgery, and its associated morbidity and mortality demand early recognition for emergency therapy. In this study, we investigated the usefulness of epicardial pacing wire (EPW) cultures for the prediction of PSM. Among 2,200 patients who underwent a cardiac surgical procedure at our hospital between 1 January 1999 and 31 December 2001, 82 (3.7%) had PSM; Staphylococcus aureus was the organism (45.1%) most frequently isolated at the time of surgical debridement. EPWs from 1,607 (73.0%) patients, 73 (4.5%) of whom developed PSM, were cultured. EPW cultures from 466 (29.0%) were positive, most often (74.9%) for coagulase-negative Staphylococci. EPW cultures were truly positive in 26 cases, truly negative in 1,106 cases, falsely positive in 428 cases, and falsely negative in 47 cases (with sterile cultures in 35 cases and a culture positive for an organism different from that isolated at the time of debridement in 12 cases). EPW culture had a positive predictive value of only 5.7% and a high negative predictive value (95.9%) for the diagnosis of PSM, with an accuracy of 70.4%. However, the likelihood ratio of positive (1.27) and negative (0.89) tests indicated only small changes in pretest-to-posttest probability. Therefore, a strategy of routine culture of EPWs to predict PSM seems questionable.

The risk of reoperative heart valve procedures in Octogenarian patients

BACKGROUND AND AIM OF THE STUDY

The authors' experience is reported of cardiac reoperations for valvular heart disease in octogenarian patients.

METHODS

The records of 22 consecutive patients (10 men, 12 women) aged > or =80 years (mean age 82.4+/-2.3 years) who underwent cardiac reoperation for aortic and/or mitral valvular heart disease at the authors' institution between 1991 and 2001 were retrospectively reviewed.

RESULTS

Indications for reoperation were structural dysfunction of a previously implanted bioprosthetic valve in 11 patients (50%), new valvular heart disease in six (27%), progression of rheumatic valvular heart disease in four (18%), and prosthetic valve infective endocarditis in one patient (5%). Fourteen patients (64%) underwent isolated aortic valve replacement (AVR), two (9%) had AVR plus coronary artery bypass grafting (CABG), one patient (5%) had aortic root replacement plus CABG, three patients (14%) had isolated mitral valve replacement (MVR), one patient (5%) had MVR plus ascending aorta replacement, and one (5%) had AVR plus MVR. Postoperative complications occurred in 18 patients (82%). The hospital mortality rate was 32%. Actuarial survival estimates at one year, and at three and five years were 62.6%, 56.3% and 40.2%, respectively.

CONCLUSION

Cardiac reoperations for valvular heart disease in octogenarians carry a high postoperative morbidity and mortality. These findings must be taken into account in the management of associated mild or moderate valvular heart disease, and in the choice of heart valve prosthesis at the initial operation in younger patients.

Platelet activation and aggregation profile in prolonged external ventricular support

BACKGROUND

Platelet function plays a major role in the understanding of thromboembolic events in prolonged mechanical support. We studied the platelet activation, platelet aggregation profile, and efficacy of aspirin in patients in whom an external ventricular assist device had been implanted.

PATIENTS AND METHODS

Fifteen patients were studied prospectively up to 6 weeks after implantation of the same type of ventricular assist device. Platelet function was studied weekly before daily aspirin administration. Aspirin efficacy was tested ex vivo by measuring platelet aggregation triggered by arachidonic acid. Flow cytometry was used to quantify the spontaneous and induced (adenosine diphosphate stimulation) expression of glycoproteins alphaIIbbeta3, Ibalpha, and CD62P on platelet membranes. The plasma levels of von Willebrand factor (von Willebrand factor activity and von Willebrand factor antigen) and fibrinogen were also determined.

RESULTS

Six of the 15 patients (26%) maintained an arachidonic acid-induced platelet aggregation despite daily aspirin treatment (250 mg). CD62P values remained increased during a 5-week postoperative period. Spontaneous levels of glycoproteins alphaIIbbeta3 and Ibalpha on platelet membranes remained within a normal range with a preserved reactivity. The plasma levels of fibrinogen and von Willebrand factor remained increased during the entire study period.

CONCLUSION

In patients with an implanted external ventricular assist device, the platelet activation profile displays a persistent activation with a preserved reactivity associated with a persistent high inflammatory state and endothelial activation.

Nosocomial infections occurring during receipt of circulatory support with the paracorporeal ventricular assist system

This retrospective study sought to report the spectrum of infections in a homogenous group of 39 patients who underwent implantation of the Thoratec paracorporeal ventricular assist device system (Thoratec Laboratories) in an emergency setting. Thirty-one of the 39 patients developed a total of 99 nosocomial infections (attack rate, 79.5%; incidence, 4.9 per 100 support-days). The lungs were the most frequently involved site (31.3%), and coagulase-negative Staphylococcus species were the pathogens most frequently isolated (16.2%). Infected patients required more transfusions and chest surgical revisions, as well as a longer duration of mechanical ventilation and a longer stay in the intensive care unit, compared with uninfected patients. Cox regression analysis revealed that chest surgical revision was the only independent risk factor for infection at any site (odds ratio, 2.6; 95% confidence interval, 1.2-5.7). There was no significant effect of infection on heart transplantation rate and overall survival.

Long-term results of the bentall operation versus separate replacement of the ascending aorta and aortic valve

BACKGROUND AND AIMS OF THE STUDY

Aortic valve disease associated with ascending aorta dilatation can be treated either by separate replacement of the aortic valve and ascending aorta, or by a composite valved graft.

METHODS

Between 1974 and 1999, 117 patients underwent a Bentall operation (BP), and 63 a separate replacement procedure (SP) of the ascending aorta and aortic valve. Anatomic lesions were dystrophic aneurysm in 79 patients, annuloectasia in 65, chronic dissection in 14, acute dissection in 18, and other etiology in four. Mean follow up was 3.45+/-3.47 and 8.75+/-6.8 years in the BP and SP groups, respectively.

RESULTS

Early mortality was 7.7% in the BP group versus 11% in the SP group (p = NS). Actuarial survival at 10 years postoperatively in these groups was respectively 77.7+/-5.6% versus 75.8+/-6.9% (p = NS). However, freedom from late complication of the ascending aorta was significantly different (97.3+/-1.9% versus 68.3+/-9.0% at 10 years postoperatively). SP was identified as a risk factor for late complication of the ascending aorta by multivariate analysis (p = 0.01; odds ratio = 9). No statistical difference was observed on late reoperation rates.

CONCLUSION

Separate replacement of the ascending aorta and aortic valve carries a higher complication rate for the remaining ascending aorta on long-term follow up when compared with the Bentall procedure. However, there were no differences in terms of late mortality.

[Computer-assisted coronary surgery]

Routine totally endoscopic, beating heart, coronary surgery should be made possible by the use of computer enhanced surgical techniques. It includes a totally endoscopic mammary artery harvesting, a correct exposure and an adequate stabilization of the coronary artery at the anastomotic site, a perfect anastomosis of the mammary artery on the left anterior descending coronary artery using a microsurgical suture technique. This complex surgical protocol will be reached by a step by step approach. The first 20 patients who accepted to be operated with tele-manipulated instruments make the substance of this first report. In 19 cases, the dissection of the internal mammary artery could be performed with an optimal result: the lack of bleeding during the dissection emphasizes the excellent visualization of the operative field and the precision of the dissection. The satisfactory blood flow in the mammary artery at the time of the coronary anastomosis suggests the lack of spasm and confirms the atraumatic dissection. The distal anastomosis of the coronary bypass has been performed through a mid line sternotomy to avoid an excessive prolongation of the operative time. The anatomic conditions and the quality of the vessel wall allowed to perform the coronary anastomosis with the tele-manipulated instruments in nine cases only: in six patients, the mammary artery has been implanted on the descending artery, in three, a venous autograft on the diagonal branch. Our initial clinical experience with this new technique suggests that a very precise and fine surgery can be performed with an acceptable prolongation of the operative time. More experience and further developments in the instrumentation are nevertheless required to allow completion of the entire procedure totally closed chest, on a beating heart.

Aortic wall alterations after use of gelatin-resorcinol-formalin glue

We report the case of a patient who underwent reoperation 8 years after aortic valve replacement because of aneurysmal dilatation of the aortic root. During the initial intervention, gelatin-resorcinol-formalin glue had been applied on the outside of the aortic root. Perioperative examination revealed a necrotic appearance of the right coronary sinus, with contained ruptures at two different sites. Histologic analysis showed major destruction of the aortic root media, leading to vascular wall thinning and rupture. The use of gelatin-resorcinolformalin glue may expose patients to major alterations of the aortic wall.

Risk factor analysis for proximal and distal reoperations after surgery for acute type A aortic dissection

OBJECTIVE

This study was undertaken to determine significant risk factors for proximal or distal reoperations after surgical correction of acute type A aortic dissection.

METHODS

Between 1980 and 2000, a total of 160 consecutive patients (mean age 57.5 +/- 13.3 years, 126 men) underwent surgery for acute type A aortic dissection. Proximal repair was performed by means of ascending aorta replacement with valve resuspension in 130 cases (81.3%), composite graft replacement in 19 cases (11.9%), separate aortic valve and ascending aorta replacement in 7 cases (4.4%), and aortic repair in 1 case (0.6%). Distal repair required arch replacement in 23 cases. Follow-up time averaged 4.51 +/- 5.6 years per patient.

RESULTS

Survival estimates after initial operation were 66.1% +/- 3.8%, 57.7% +/- 4.2%, 52.2% +/- 4.6%, and 42.5% +/- 5.8% at 1, 5, 10, and 15 years, respectively. Thirty patients required 37 reoperations at a mean interval of 5.7 +/- 4.5 years after the initial operation. Freedoms from reoperation were 96.9% +/- 1.8%, 74.7% +/- 5.3%, 60.8% +/- 6.8%, and 39.3% +/- 9.1% at 1, 5, 10, and 15 years, respectively. Reoperations included procedures on the proximal aorta (aortic root or valve) in 21 cases and on the distal aorta or its side branches in 19 cases. Cox regression analysis distinguished severe preoperative aortic valve insufficiency as the only significant risk factors for proximal reoperation; younger patient age, more distal extent of dissection, and more recent operative date were found to be significant risk factors for distal reoperation.

CONCLUSION

Patients with acute type A aortic dissection who have severe aortic valve insufficiency are at increased risk for proximal reoperation. These patients should benefit from a more aggressive proximal repair at initial operation. Distal extent of aortic resection at initial operation did not significantly influence the risk of distal reoperation.

[Long-term results of surgery for type A acute aortic dissection]

The cases of 160 patients (126 men, mean age 57.5 +/- 13.3 years) operated consecutively as an emergency for a Stanford type A dissection of the aorta between 1980 and 2000 were reviewed. The cumulative follow-up was 716.7 patient-years with an average follow-up of 4.51 +/- 5.6 patient-years. The risk factors for early postoperative mortality (up to 3 months), late mortality (> 3 months) and reoperation (cardiac and/or vascular) were determined by multivariate analysis. The hospital mortality was 27.5%. Older ages, obesity, previous cardiac surgery, preoperative shock, medullary, renal or mesenteric ischaemia were significant risk factors for early mortality. The probability of actuarial survival was 66.1 +/- 3.8%, 57.7 +/- 4.2%, 52.2 +/- 4.6% and 45.3 +/- 5.5% respectively at 1, 5, 10 and 15 years. Chronic obstructive airways disease and a more recent operation date were significant risk factors for late mortality. Thirty patients underwent 37 reoperations after an average of 5.7 +/- 4.5 years. The actuarial probability for no reoperation was 96.9 +/- 1.8%, 74.7 +/- 5.3%, 60.8 +/- 6.8% and 39.3 +/- 9.1% at 1, 5, 10 and 15 years respectively. The presence of severe preoperative aortic regurgitation was the only significant risk factor for reoperation. Type A acute dissection of the aorta continues to have a high early mortality and a significant incidence of late complications. Patients with severe aortic regurgitation before surgery are at high risk for reoperation and should probably have more radical aortic repair at the initial operation.

Silzone-coated St. Jude medical valve: a safe valve

Careful follow up studies in patients receiving a Silzone-coated St. Jude Medical valve (67 aortic valves, 36 mitral valves, nine double valves) did not support the fear of a high risk of perivalvular leak and embolism rate. Freedom from perivalvular risk at 12 and 24 months follow up was 98.5+/-1.5% and 100% for the aortic and mitral valves, respectively. Freedom from any thromboembolic event was 96.6+/-2.4% at 12 and 24 months follow up in the aortic group, and 97+/-3% at 12 and 24 months in the mitral group. The risk of bleeding (92.2+/-3.8% at 12 and 24 months in the aortic group; 85.5+/-6.0% in the mitral group) illustrated the risk of mechanical valve implantation in an elderly population.

Immunologic events and long-term survival after combined heart and kidney transplantation: a 12-year single-center experience

BACKGROUND

In this study we compare the incidence of cardiac rejection and long-term survival after combined heart and kidney transplantation (HK) and single heart transplantation (H). Combined HK transplantation is a surgical option for patients with irreversible cardiac and renal failure. However, long-term results of combined HK transplantation on immunologic events and patient survival remain unknown.

METHODS

Between 1988 and 1997, 12 consecutive patients underwent combined HK transplantation (HK group) at a single institution. A control group (H group) of 24 single heart transplant recipients operated on within the same period was matched for age, pre-operative pulmonary vascular resistance, hepatic insufficiency and gender mismatch. Recipients and donors were ABO compatible without HLA antigen matching. All patients received immediate triple immunosuppression that included cyclosporine. Because of early renal dysfunction, cyclosporine was switched to anti-thymocyte globulin in 5 patients from the HK group and in 1 patient from the H group (p = 0.01).

RESULTS

Actuarial freedom from heart rejection at 6 months and at 1 year following transplantation averaged 90 +/- 9% and 70 +/- 14% in the HK group, and 65 +/- 10% and 49 +/- 11% in the H group, respectively (p = 0.023). Actuarial survival at 1, 5 and 12 years was not significantly different between groups, at 66%, 55% and 28% in the HK group, and 66%, 44% and 32% in the H group, respectively (p = 0.66).

CONCLUSION

The incidence of cardiac rejection was significantly lower. Long-term survival in the HK group was similar to that in the H group. Putative mechanisms of decreased cardiac rejection in the HK group include allogeneic stimulation, donor-derived dendritic cells and induction by anti-thymocyte globulins. The need for long-term immunosuppression may be reduced after combined heart and kidney transplantation.

Spontaneous hemomediastinum complicating steroid-induced mediastinal lipomatosis

Spontaneous hemomediastinum is a rare event, occurring in association with bleeding disorders, intratumoral bleeding, or following an abrupt increase in intrathoracic pressure. We report the case of a patient with systemic lupus erythematosus, nephrotic syndrome, and renal failure, in whom mediastinal lipomatosis (ML) developed following increased corticosteroid therapy. Anticoagulant therapy likely precipitated a massive spontaneous hemomediastinum secondary to diffuse hemorrhage of mediastinal fat, which required emergency decompressive surgery. Steroid-induced ML is common and usually well tolerated, but clinicians should be aware of its potential risk of bleeding when associated with anticoagulant therapy. This case further emphasizes the bleeding complications of treatment with low-molecular-weight heparin in patients with renal failure.

Pseudointima in Inflow and Outflow Conduits of a Left Ventricular Assist System: Possible Role in Clinical Outcome

Activation of blood coagulation and thromboemboli have been shown to present significant clinical risks in patients supported with an left ventricular assist system (LVAS). The interaction of pseudointima (PI) with blood in the conduits of the device could be involved in these clinical complications. Our aim was to study the morphology of the PI versus duration of circulatory support. Novacor N 100 PC LVASs were explanted from 10 men and 2 women after a mean of 209 days (range 23-560 days) of circulatory assistance. PI in the inflow and outflow conduits were investigated with immunohistochemical assays. In the inflow conduits, a loosely adherent PI had built up from collagen type I and III fibers growing into and between fibrin deposits. Disorganized collagenous matrix and longitudinally oriented collagen fibers included alpha-smooth muscle actin positive cells with random orientation. Macrophages were concentrated in the fibrin and were dispersed throughout the extracellular matrix. In the outflow conduits, a thin, adherent PI was composed of regular collagen type I and III layers. Collagen type I fibers had grown into the woven Dacron and alpha-smooth muscle actin positive cells were oriented in the axis of the blood flow. Macrophages were concentrated in the Dacron and reached the inner collagen layers. Venous blood flow in the inflow conduits allows the development of a non endothelialized irregular collagenous matrix intermingled with fibrin and invaded by macrophages. These persistent structural features progress with duration of circulatory assistance and reflect matrix degradation and remodeling. The potential to release thromboembolic fragments from the non stable, thrombogenic PI may be involved in the thromboembolic or neurologic complications sustained by 5 of 12 patients who were on circulatory support for as long as 200 days.

Closed drainage using redon catheters for poststernotomy mediastinitis: results and risk factors for adverse outcome

BACKGROUND

Several different surgical techniques have been described for the treatment of poststernotomy mediastinitis. The present study was undertaken to evaluate the midterm results of primary closed drainage using Redon catheters and to identify risk factors for adverse outcome.

METHODS

Hospital records of 72 patients in whom poststernotomy mediastinitis developed and who underwent closed drainage with Redon catheters between April 1, 1996, and December 31, 1999, were reviewed. Follow-up was complete and averaged 11.8 +/- 11.5 months.

RESULTS

Of the 25 deaths (34.7%) recorded, 15 were directly attributable to mediastinitis. Actuarial estimates for freedom from mediastinitis-related death were 80.1% at 1 month and 77.4% at 1 year, 2 years, and 3 years. Logistic regression identified older age (odds ratio, 1.1; 95% confidence interval, 1.02 to 1.18), incubation time of 14 days or less (6.5; 1.33 to 31.4), and methicillin-resistant Staphylococcus aureus (5.8; 1.2 to 27.2) as independent risk factors for mediastinitis-related death. Reintervention for recurrent mediastinitis was necessary in 9 patients (12.5%) and occurred at a mean interval of 18.7 +/- 13.5 days from the first debridement. Actuarial estimates for freedom from reintervention were 87.1% at 1 month and 85.2% at 1 year, 2 years, and 3 years. The combined end point of treatment failure (mediastinitis-related death or reintervention) was recorded in 9 patients (26.4%). Actuarial estimates for freedom from treatment failure were 74.3% at 1 month and 72.7% at 1 year, 2 years, and 3 years. Logistic regression identified older age (1.01; 1.02 to 1.18), preoperative renal insufficiency (6.8; 1.04 to 44.5), and methicillin-resistant S aureus infection (4.8; 1.04 to 22.33) as independent risk factors for treatment failure (includes mediastinitis-related death and reintervention [with or without death]).

CONCLUSIONS

Primary closed drainage using Redon catheters is an effective and simple treatment for most patients in whom poststernotomy mediastinitis develops. However, patients with methicillin-resistant S aureus infection or recurrent mediastinitis may benefit from a more aggressive approach.

Risk factors for post-cardiopulmonary bypass vasoplegia in patients with preserved left ventricular function

BACKGROUND

Although vasodilatory shock (VS) is one of the main complications of cardiopulmonary bypass (CPB), its pathophysiologic basis remains unclear. The aim of this study was to identify predisposing factors for the development of VS after CPB independent of ventricular function.

METHODS

Thirty-six patients undergoing coronary artery bypass grafting who developed VS were compared with 72 control patients without post-CPB cardiogenic or vasoplegic shock, in a 2:1 case control study. Patients and controls underwent the same anesthetic protocol and were matched by age, sex, operation date, and left ventricle ejection fraction.

RESULTS

Preoperative and intraoperative patient characteristics were not significantly different between the two groups. Preoperative use of angiotensin-converting enzyme inhibitors and intravenous heparin were independent predictors for post-CPB VS by multivariate analysis (relative risk of 2.26 and 2.78, respectively). Intensive care unit stay and hospital stay were significantly longer in VS cases than controls, without any difference in early postoperative mortality.

CONCLUSIONS

The only independent risk factors for postoperative VS identified were preoperative use of angiotensin-converting enzyme inhibitors and intravenous heparin. These risk factors were independent of age, gender, anesthetic protocol, and left ventricle ejection fraction.

Doppler tissue imaging to predict myocardial recovery during mechanical circulatory support

Bridge to recovery is a possibility for patients receiving mechanical circulatory support. However, no reliable factors exist to predict a sustained myocardial recovery. We report the use of a new technique of Doppler tissue imaging to document myocardial recovery in two cases with promising results.

[Circulatory assistance while waiting for heart transplantation. Patient selection and choice of the assist system]

TWO CLINICAL SITUATIONS: Mechanical circulatory assistance can be indicated in two clinical situations: i) patients on the waiting list for heart transplantation who have chronic heart failure unresponsive to drug therapy and whose clinical status worsens; ii) patients with acute heart failure.

INDICATIONS

The exact indications for mechanical circulatory assistance are difficult to establish. Hemodynamic criteria are no longer sufficient. Circulatory assistance may be proposed for chronic heart failure patients with a high risk of death or in a situation of acute deterioration. Among these patients, several risk factors can be used to establish scores that have a better predictive value than risk factors taken alone. Two predictive models have been recently established. The first one takes into account 7 independent variables: etiology, heart rate at rest, left ventricle ejection fraction, mean blood pressure, intraventricular rhythm disorder, VO2max and serum sodium). In addition to these variables, the second model also includes pulmonary wedge pressure. In selected patients with acute heart failure, circulatory assistance is needed as early as possible to avoid irreversible multiple organ failure. The crucial problem is rapid assessment of the feasibility of heart transplantation.

PREOPERATIVE MORTALITY RISK FACTORS

Several variables can be used to predict survival in candidates for mechanical circulatory assistance on the heart transplantation waiting list. They include hemodynamic criteria, renal function, liver function, preoperative infection and the emergency nature of the need for circulatory assistance.

CHOICE OF THE ASSIST SYSTEM

The choice depends both on the patient (surface area is important) and the underlying disease.

[Circulatory assistance while waiting for heart transplantation. Clinical course]

OUTCOME

In most cases, mechanical circulatory assistance prior to transplantation can restore the main vital functions allowing a progressive physical rehabilitation during the period of assistance. According to several international registries, the transplantation rate ranges from 62% to 69% and the proportion of transplanted patients who had circulatory assistance and who were discharged ranges from 65% to 69%.

COMPLICATIONS

Bleeding (42.5%), right heart failure (20-25%), air embolism and multiple organ failure are the main causes of early morbidity and mortality. Infection (28.5%), thromboembolic events and technical failures are the most frequent late complications.

DURATION OF CIRCULATORY ASSISTANCE

The optimal time for transplantation is the moment when the incidence of complications and technical problems for transplantation are at their minima while the patient's vital functions are at their maxima.

[Circulatory assistance while waiting for heart transplantation. Outcome of heart transplantation after mechanical circulatory assistance]

SURVIVAL

In most of the published (uncontrolled) studies, survival after transplantation is similar for patients who required mechanical circulatory assistance and those who did not. Two controlled studies have reported a better survival rate in patients who had preoperative circulatory assistance.

COMPLICATIONS

Infections are more frequent in transplanted patients who had a period of circulatory assistance preoperatively than in those who were transplanted after medical treatment. The effect of circulatory assistance on heart graft rejection is debated. The same is true for coronary grafts.

[External ventricular support in primary cardiogenic shock]

Primary cardiogenic shock is a common condition with a high mortality rate. In this indication, mechanical assist plays an important part and has improved a lot over the last decade. The authors report their experience with the same assist device in patients with primary cardiogenic shock. Nineteen patients (9 dilated cardiomyopathies, 7 myocardial infarctions, 2 myocardities, 1 undetermined) were treated with an external mechanical ventricular assist device (Thoratec, Berkeley, U.S.). Fourteen patients received a biventricular assist and 5 had a uni-left ventricular assist device. Four of the 19 patients were completely weaned off their ventricular assist after 13, 27, 36 and 94 days, respectively. Ten patients underwent transplantation after an average of 43 days (range 8-95 days). Of the 19 patients, 7 had a portable console allowing autonomous ambulation. Five patients died under mechanical assistance (26.9%) and 3 patients died after transplantation. Three patients required temporary haemodialysis; 4 suffered embolic complications; 4 had mediastinal haemorrhages; 4 had bleeding from other sites, and 6 suffered from late tamponnade. Fourteen patients had at least one infectious episode. The authors conclude that, in patients referred for severe primary cardiogenic shock, the implantation of an external biventricular assist is a reliable option, allowing sequential weaning or being a bridge to transplantation in non-dependent patients, providing they are severely selected.

Structural changes in porcine bioprosthetic valves of a left ventricular assist system in human patients

BACKGROUND AND AIM OF THE STUDY

Porcine, specially manufactured bioprosthetic valves regulate blood flow from the left ventricle to pump sac (inflow valve) and from the pump to the aorta (outflow valve) in a wearable, electrically powered left ventricular support system (LVAS, Novacor). The increased need for long-term circulatory assistance requires information on the evolution of these valves when exposed to specific hemodynamic conditions and inflammatory reactions in the device. The study aim was to examine structural changes in valves from explanted LVASs.

METHODS

Thirteen patients (11 males, two females; mean age 42 years (range: 17-64 years) were supported for a mean of 285 days (range: 37-1,293 days) with LVAS. Histologic sections from explanted inflow and outflow valves were studied immunohistochemically using peroxidase-labeled antibodies and avidin-biotinylated peroxidase complex for detection.

RESULTS

In the macroscopically normal inflow valves (11/13), the outflow surface (facing the pump) was covered with a discontinuous deposit of fibrin, macrophages and granulocyte elastase. Fibrinogen, IgG, complement proteins C1q and C3 had infiltrated the extracellular matrix (ECM) between 37 and 1,293 days. The crevices were enlarged during circulatory support, and fibrinogen/fibrin insudations were detected in the spongiosa. The collagen layers in the fibrosa were disrupted after 293 days, and eroded on the inflow surface in the ventricularis after 1,293 days. In a deteriorated valve from a patient with endocarditis, Gram-positive bacteria and metalloproteinases were concentrated in the ECM. In the macroscopically normal (11/13) outflow valves, fibrin and complement proteins had penetrated the ECM from the inflow side (facing the pump), while macrophages and granulocytes were localized mainly on the outflow surface. IgG and complement proteins were detected on and beneath the cusp surface up to 200 days and covered the disrupted ECM as implant time progressed.

CONCLUSIONS

Structural changes appear to progress more rapidly in the inflow than in the outflow of bioprosthetic valves. This difference indicates that the effects of biological factors are modulated by mechanical stress.

Myocardial recovery after mechanical support for acute myocarditis: is sustained recovery predictable?

BACKGROUND

At present, myocardial recovery with mechanical support for acute myocarditis is a more frequently observed issue. However, predictive parameters of a sustained myocardial recovery are still under investigation.

METHODS

Two recent cases of mechanical support for acute lymphocytic myocarditis with two different outcomes are reported. Literature about this disease and predictability of a sustainable myocardial recovery are reviewed.

RESULTS

Acute lymphocytic myocarditis is an individual entity whose outcome is associated with the importance of healed cell damage. Unfortunately, there are no available means of quantifying the fibrotic scar and endomyocardial biopsy has a high percentage of false-negative results. Echocardiographic assessment of systolic and diastolic cardiac function is difficult while under mechanical support and its significance is not obvious. Forthcoming development of Doppler could better correlate myocardial contractility and histology to be predictive of a sustained recovery after acute myocarditis under mechanical support.

CONCLUSIONS

Long-lasting recovery after mechanical support for acute myocarditis remains unpredictable in our experience. More predictive factors are needed.

Comparison between angiotensin receptor antagonism and converting enzyme inhibition in heart failure. Differential acute effects according to the renin-angiotensin system activation

This study was designed to assess the influence of the activation status of the renin angiotensin system (RAS) on the hemodynamic effects of EXP 3174 (an angiotensin AT1 receptor antagonist) and enalaprilat (an angiotensin converting enzyme inhibitor) in tachycardia-induced heart failure. Thirteen dogs were chronically instrumented to measure left ventricular (LV) pressure, its first time derivative (LV dP/dt), atrial and aortic pressures, and cardiac output. EXP 3174 (0.1 mg/kg, i.v.) or enalaprilat (1 mg/kg, i.v.) were administered in conscious dogs with heart failure induced by right ventricular pacing (250 beats/min, 3 weeks). EXP 3174 and enalaprilat produced significant vasodilation but the effects of EXP 3174 on mean aortic pressure (MAP), cardiac output, and total peripheral resistance (TPR) were only 50% of those produced by enalaprilat. When dogs were grouped according to their baseline plasma renin activity (PRA) values, in dogs with normal PRA (0.5 +/- 0.1 ng/ml/h) EXP 3174 did not produce significant change in MAP and TPR, while enalaprilat decreased significantly MAP and TPR. In contrast, in dogs with high PRA (6.7 +/- 3.2 ng/ml/h), EXP 3174 produced significant reductions in MAP and TPR, which were similar to those produced by enalaprilat. Thus, in conscious dogs with heart failure, enalaprilat is effective whether the RAS is activated or not. In contrast, EXP 3174 is effective only when the RAS is activated. These results may help in the choice of inhibitors of the RAS in heart failure.

Tracheoplasty in congenital tracheal stenosis

Congenital tracheal stenosis is an uncommon but life-threatening condition whose management is still debated. The rarity of this disease explains the lack of a standard management. Between 1986 and 1996, eight children younger than 1 year were referred to our Institution with a tracheal stenosis. The median age at operation was 3.15 months and the median weight was 4.5 kg. The diagnosis was made after an episode of respiratory distress in all but one and was confirmed by fiberoptic bronchoscopy. The median length of tracheal stenosis was 24.5 mm (Ranges: 4-30 mm). Only one patient was free from associated cardiovascular defect. Tracheal repair was performed under cardiopulmonary bypass in all. In three it was achieved by pericardial augmentation of the stenosed area, in four by resection and end to end anastomosis and in one by sliding tracheoplasty. Concomitant cardiac repair was performed in six. Two patients died after pericardial patch augmentation. In both, death was related to profound hypoxemia due to patch collapse. Two patients developed restenosis after resection and end to end anastomosis. They both had stent placement and one required reoperation and underwent a sliding tracheoplasty. At a median follow-up of 21 months (Ranges: 6-120) all the survivors are doing well and are free from respiratory symptoms. Bronchoscopic evaluation revealed in all a widely patent anastomosis without restenosis. In conclusion, tracheal stenosis in children remains a challenging lesion. Surgical technique, whether resection and end to end anastomosis or sliding tracheoplasty offer better results and should be discussed according to the length of the stenosis. Pericardial plasty should be used with caution.