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Biomedical subjects

Donald D Glower

Publications and source records attributed to Donald D Glower.

At least 19 recordsLinked to original sources
PubMed2006

Systolic contraction within aneurysmal rabbit myocardium following transplantation of autologous skeletal myoblasts.

OBJECTIVE: Transplantation of autologous skeletal myoblasts (SKMB) into infarcted heart (or cellular cardiomyoplasty, CCM) augments myocardial performance in animal models of myocardial infarction. However, the effect of CCM in the setting of ventricular aneurysm has not been evaluated. This study analyzes the effects of transplanted SKMB on regional wall motion in a rabbit model of postinfarct ventricular aneurysm. We hypothesize that CCM, performed early after myocardial infarction, prevents the progression of dyskinetic wall motion. METHODS: Twenty-six rabbits underwent apical left ventricular cryoinfarction and soleus muscle biopsy for in vitro isolation of skeletal myoblasts. At 2 weeks postinfarct, the presence of ventricular aneurysm was detected in 23/26 animals by sonomicrometry and micromanometry. Seventeen of 23 animals were randomized to receive either 108 autologous myoblasts (CCM) or vehicle. Regional stroke work, percent systolic shortening, and synchronicity of regional wall motion were determined prior to, and four weeks following, injection (CCM; n = 9; vehicle, n = 8). Wall motion was evaluated under baseline and stress (dobutamine, 10 (g/kg/min) conditions. Six animals did not undergo randomization, but their hearts were used to measure the size of infarction. RESULTS: Four weeks following treatment of animals with ventricular aneurysm, systolic contractile activity was present in most animals treated with myoblasts but in none treated with vehicle (5/7 versus 0/6, respectively, P < 0.05). Dobutamine tended to accentuate the differences seen at baseline between the groups. CONCLUSIONS: This study demonstrates a high incidence of systolic contractile activity in a previously aneurysmal region of myocardium following CCM and may represent a novel therapy for the prevention and treatment of postinfarct aneurysm.

Animals↗
PubMed2006

"Adjustable" artificial chordal replacement for repair of mitral valve prolapse.

Achieving a stable repair of mitral valve prolapse can be difficult in complex pathologies, and a 5% to 20% late reoperation rate exists with leaflet resection and reconstruction. During an 8-year period, prolapse was managed uniformly with "adjustable" Gortex (W. L. Gore & Associates Inc, Flagstaff, AZ) artificial chordal replacement and Carpentier ring annuloplasty (Edwards Lifesciences LLC, Irvine, CA), without leaflet resection. Artificial chords were placed initially in the papillary muscles, and then after ring annuloplasty they were adjusted to optimize length to the prolapsing segment(s). Of 52 patients with prolapse, 100% were repaired successfully with artificial chords. Operative mortality was 1.9%, and 4, 6, and 8-year survivals were 87%, 81%, and 71%, respectively. Only 1 of 52 patients (1.9%) experienced late failure, and this patient was re-repaired with artificial chords. Thus, "adjustable" artificial chordal replacement facilitates uniform repair of mitral valve prolapse with a low late failure rate.

Cardiac Surgical Procedures↗
PubMed2006

Short-term and intermediate-term outcomes of aortic root replacement with St. Jude mechanical conduits and aortic allografts.

BACKGROUND: Few studies have directly evaluated outcomes in patients undergoing aortic root replacement with St. Jude mechanical conduits or aortic allografts (ALLO), yet both approaches have been advocated. The purpose of this study was to provide a detailed description of outcomes in a large series of aortic root replacements performed with either St. Jude mechanical conduits or aortic allografts. METHODS: A retrospective analysis was performed on 172 consecutive adult patients undergoing aortic root replacement with either St. Jude mechanical conduits (n = 73) or aortic allografts (n = 99) from January 1990 to December 2002. Maximal follow-up was 15 years, and median follow-up was 5 years. RESULTS: Both groups were similar with regard to median age, preoperative ejection fraction, and New York Heart Association class. The aortic allograft patient group had a higher proportion (p < 0.05) of women (43% versus 18%), prior sternotomies (52% versus 26%), preoperative renal failure (9% versus 1%), and cerebrovascular disease (16% versus 4%). Operative indications for the aortic allograft group were more frequently endocarditis (29% versus 3%; p < 0.0001) and prosthetic valve dysfunction (13% versus 1%; p < 0.01), and less frequently annuloaortic ectasia (34% versus 60%; p < 0.001) or aortic dissection (3% versus 26%; p < 0.0001). Concomitant coronary artery bypass grafting or other valve surgery was performed in 30% of patients in both groups. Incidence of early postoperative complications, including bleeding, stroke, renal failure, and respiratory failure, was similar in both groups. Thirty-day mortality was 5.5% in the St. Jude mechanical conduit group and 8.1% in the aortic allograft group (p = 0.4). Unadjusted actuarial survival at 1, 5, and 10 years was 90%, 81%, 67%, and 86%, 70%, 67%, for the St. Jude mechanical conduit and aortic allograft groups, respectively (p = 0.09). Event-free survival at 1 and 5 years was similar for both groups (p = 0.4). By multivariate analysis, New York Heart Association class III or IV, emergently performed aortic root replacement, and postoperative respiratory failure, but not valve conduit type (p = 0.3), were independent predictors of mortality. CONCLUSIONS: Aortic root replacement can be safely performed with either allograft or mechanical conduits, even in the setting of acute dissection, redo sternotomy, or endocarditis.

Adult↗
PubMed2006

Minitransseptal versus left atrial approach to the mitral valve: a comparison of outcomes.

BACKGROUND: Approaches to the mitral valve include left atriotomy (LA) through the interatrial groove and transseptal approach (TS) through the right atrium. Left atriotomy is more commonly used, but TS offers better mitral visualization in difficult cases. While TS has been associated with more atrial arrhythmias, heart block, and difficulty in repair, strong data are lacking. METHODS: Retrospective chart review was conducted of 531 consecutive patients undergoing a mitral valve procedure through sternotomy by a single surgeon between 1989 and 2003. Of these, 273 were performed through the standard LA approach and 258 by a "minitransseptal" approach consisting of a 6-cm vertical incision in the interatrial septum without incising the roof of the right or left atria. RESULTS: Subset analysis of isolated mitral procedures showed no significant differences in cross-clamp time or total bypass time. Although significantly more TS patients required new pacemakers (10.5% TS versus 5.1% LA) or had new junctional rhythm (8.7% TS versus 4.2% LA), TS patients also had more concomitant valve procedures and redo sternotomies. Multivariate analysis showed that the incidence of new pacemakers was linked most strongly with redo procedures, but TS was not an independent predictor of needing a new pacemaker, new junctional rhythm, or new atrial fibrillation. CONCLUSIONS: The minitransseptal approach can provide excellent mitral valve exposure in difficult cases without any significant increase in junctional rhythm, atrial fibrillation, or new pacemaker requirements.

Aged↗
PubMed2006

Determinants of operative mortality in valvular heart surgery.

OBJECTIVE: In some respects, outcome reporting in valvular surgery has been hampered by focusing on specific populations, reluctance to publish high-risk subgroups, and possibly skewed or inadequate samples. The goal of this study was to evaluate risk factors for operative mortality comprehensively across the entire spectrum of cardiac valvular procedures over the past decade. METHODS: All 409,904 valve procedures in the Society of Thoracic Surgeons database performed between 1994 and 2003 were assessed, and Society of Thoracic Surgeons preoperative and operative variables were related to operative mortality by using a multivariable logistic regression model. Data were greater than 95% complete, and the relative importance of relevant risk factors was determined by ranking odds ratios. The analysis had a high predictive power, with a C statistic of 0.735. RESULTS: In the model, 19 variables independently influenced operative mortality (all P < .01). The most significant was nonelective (acute) presentation (odds ratios, 2.11), followed by advanced age (odds ratios, 1.88), reoperation (odds ratios, 1.61), endocarditis (odds ratios, 1.59), and coronary disease (odds ratios, 1.58). Generally, valve replacement was associated with higher mortality than repair (odds ratios, 1.52). Overall, female gender was very important (odds ratios, 1.37), and earlier year of operation increased risk (odds ratios, 1.34), implying improving outcomes over time. Although any single comorbidity, on average, was only moderately contributory (odds ratios, 1.19), specific comorbidities, such as renal failure, or multiple comorbidities in a given patient could be very significant. Aortic root reconstruction carried the highest risk (odds ratios, 2.78), followed by tricuspid valve surgery (odds ratios, 2.26), multiple valve procedures (odds ratios, 2.06), and then isolated mitral (odds ratios, 1.47), pulmonic (odds ratios, 1.29), and aortic (reference procedure) operations. Reduced ejection fraction and severity of valve lesion were relatively less important (odds ratios, 1.34 and 0.83, respectively). CONCLUSIONS: These data illustrate the significance of acute presentation in determining operative risk, and earlier surgical intervention under elective conditions might be emphasized for all types of significant valve lesions. Because aortic root reconstruction doubles mortality compared with simple aortic valve procedures, root replacement should be reserved for specific root pathology. Finally, issues related to reoperation, endocarditis, valve repair, gender, and the various procedures deserve more detailed examination.

Aged↗
PubMed2005

Impact of mitral valve regurgitation evaluated by intraoperative transesophageal echocardiography on long-term outcomes after coronary artery bypass grafting.

BACKGROUND: It is unclear if mild or moderate mitral valve regurgitation (MR) should be repaired at the time of coronary artery bypass grafting (CABG). We sought to determine the long-term effect of uncorrected MR, measured by intraoperative transesophageal echocardiography (TEE), in CABG patients. METHODS AND RESULTS: Between May 1999 and September 2003, data were gathered for 3264 consecutive patients who underwent isolated CABG and had MR graded by intraoperative TEE. MR was graded on the following 5 levels: none, trace, mild, moderate, and severe. Patients who had severe MR or who underwent mitral valve surgery were eliminated from the analysis. The remaining patients were combined into the following 3 groups: none or trace, mild, and moderate MR. Preoperative and follow-up data were 99% complete. The median length of follow-up was 3.0 years. Multivariable analysis controlling for important preoperative risk factors was performed to determine predictors of death and death/hospitalization for heart failure. Increasing MR was a risk factor for death [hazard ratio (HR), 1.44; P<0.001] and death/heart failure hospitalization (HR, 1.34; P<0.01). When patients with moderate MR were eliminated from the analysis, mild MR was a risk factor for death (HR, 1.34; P=0.011) and death/hospitalization for heart failure (HR, 1.34; P<0.001). CONCLUSIONS: Even mild MR, identified by intraoperative TEE, predicts worse outcomes after CABG. Revascularization alone did not eliminate the negative long-term effects of mild MR. CABG patients with uncorrected mild or moderate MR are at increased risk for death and heart-failure hospitalization; consideration for surgical repair or more aggressive medical management and follow-up is warranted.

Aged↗
PubMed2005

Isolated mitral valve repair in patients with depressed left ventricular function.

BACKGROUND: The utility of mitral valve repair (MV repair) has been well documented in patients with normal left ventricular function. Few studies, however, have specifically examined outcomes of isolated MV repair in patients with decreased left ventricular function. The purpose of the present study is to review a modern experience with isolated MV repair in patients with depressed left ventricular function and to examine intermediate outcomes. METHODS: A retrospective review of patients who underwent MV repair from 1996 to 2003 was performed to identify consecutive patients who had isolated MV repair. Preoperative studies were reviewed to further identify patients with an ejection fraction less than 0.45. Clinical operative data were collected from the medical record, and survival was determined with the Social Security Death Index. Further end points of reoperation and transplantation were also noted. RESULTS: A total of 101 patients were identified with a mean follow-up of 1,124 days. Mean ejection fraction and age was 0.34 +/- 0.09 and 56 +/- 14 years, respectively. Thirty-day mortality was 2.9%. One- and 5-year survival was 94% +/- 2% and 70% +/- 6%, respectively. There was no statistically significant difference in actuarial survival for functional versus primary mitral disease, or for ejection fraction less than 0.35 versus greater than 0.35. Six patients required transplantation. Five-year freedom from reoperation, transplantation, and death was 61% +/- 11% and 54% +/- 8% for patients with primary and secondary mitral valve disease, respectively (p = 0.279). Minimally invasive MV repair was performed in 57 patients with a mean ejection fraction of 0.369 +/- 0.07 and a 30-day mortality of 1.7%. CONCLUSIONS: In patients with isolated MV regurgitation and depressed left ventricular function, MV repair can be achieved with low operative mortality, but there remains a persistent risk of death, reoperation, or transplantation irrespective of valve disease. Minimally invasive MV repair was safe in this group.

Cardiac Surgical Procedures↗
PubMed2005

Intracardiac transplantation of a mixed population of bone marrow cells improves both regional systolic contractility and diastolic relaxation.

BACKGROUND: Pre-clinical and clinical studies suggest that transplantation of bone marrow-derived stem cells can improve global cardiac function. However, no quantitative assessment of regional systolic contraction and correlation with phenotype has been made. Therefore, we used our model of cryoinfarcted rabbit myocardium for intracardiac transplantation of a mixed population of bone marrow-derived cells and assessed both regional function and myogenic conversion of the cells. METHODS: Nineteen New Zealand white rabbits underwent cryoinjury of the left ventricle. Autologous bone marrow (BM) cells were expanded in vitro. After 2 weeks, either 1 x 10(8) mixed BM-derived progenitor cells (BM group, n = 11) or vehicle (control group, n = 8) were injected into the cryoinjured region. Regional systolic function was measured using micromanometry and sonomicrometry before and 4 weeks after cell injection; cell phenotype was evaluated histologically. RESULTS: All animals in the BM group significantly improved both systolic shortening (0.11 +/- 0.7 vs -0.05 +/- 0.05 mm in the control group, p < 0.05) and regional stroke work when compared with control (9.6 +/- 2.4 vs -1.2 +/- 1.2 mm . mm Hg, p < 0.003). In addition, the BM group had improved global diastolic function, as measured by minimum dP/dt and end-diastolic pressure. On histologic assessment, BM cells differentiated toward a myogenic phenotype. CONCLUSIONS: Transplanting a mixed population of marrow-derived cells that can adopt a myogenic phenotype improves regional contractility and diastolic relaxation after myocardial infarction.

Animals↗
PubMed2005

Patient survival characteristics after routine mitral valve repair for ischemic mitral regurgitation.

BACKGROUND: Ischemic mitral regurgitation has been associated with diminished survival compared with nonischemic mitral regurgitation. Conversion from mitral valve replacement to valve repair has improved prognosis, but it is unclear whether ischemic mitral regurgitation remains an independent predictor of outcome after mitral valve repair. METHODS: Five hundred thirty-five patients undergoing mitral valve repair (primarily rigid ring annuloplasty) with or without coronary bypass from 1993 through 2002 were reviewed retrospectively (ischemic mitral regurgitation, n = 141; nonischemic mitral regurgitation, n = 394). A Cox proportional hazards model evaluated survival as a function of 9 simultaneous covariates: ischemic versus nonischemic mitral regurgitation, age, sex, number of medical comorbidities, ejection fraction, New York Heart Association class, coronary disease, reoperation, and year of operation. RESULTS: According to univariable analysis, patients with ischemic mitral regurgitation had greater age, higher comorbidity, lower ejection fraction, higher New York Heart Association, and higher reoperation rate (all P < .001) compared with those having nonischemic mitral regurgitation. Univariable 30-day mortality was as follows: 4.3% for patients with ischemic mitral regurgitation versus 1.3% for patients with nonischemic mitral regurgitation (P = .01). Unadjusted 5-year mortality was as follows: 44% +/- 5% for patients with ischemic mitral regurgitation versus 16% +/- 3% for patients with nonischemic mitral regurgitation (P < .001). In the multivariable model, however, only the number of preoperative comorbidities and advanced age were independent predictors of survival (P < .0001), whereas ischemic mitral regurgitation, sex, ejection fraction, New York Heart Association class, coronary disease, reoperation, and year of operation did not achieve significance (all P > .19). After being adjusted for differences in all preoperative risk factors, survival was not statistically different between ischemic mitral regurgitation and nonischemic mitral regurgitation (P = .33). CONCLUSIONS: With routine application of rigid ring annuloplasty, long-term patient survival is more influenced by baseline patient characteristics and comorbidity than by ischemic cause of mitral regurgitation per se. Future risk assessment and decision making should be based on patient condition and should not be biased by ischemic cause of mitral regurgitation.

Age Factors↗
PubMed2005

Immunotherapy for refractory pulmonary infection after adult cardiac surgery: immune dysregulation syndrome.

BACKGROUND AND AIM OF THE STUDY: Pulmonary dysfunction/multiorgan failure (PD/MF), usually due to refractory pulmonary infection, is an important cause of mortality and morbidity after cardiac operations. Moreover, the incidence of PD/MF may be increasing due to the emergence of antibiotic-resistant pathogens. METHODS: Fifteen consecutive patients (median age 69 years) who were developing antibiotic-refractory PD/MF were administered 24 g per day intravenous immunoglobulin (IV-IgG; Carimune) for five days. Ten patients had undergone complex valve surgery, and five coronary bypass. Preoperatively, 93% of patients had significant comorbidity, 73% presented acutely, 53% were hypoalbuminemic and 47% had antecedent acute pulmonary derangement. Clinical variables were assessed by retrospective chart review for three days prior to (-3) the start of IV-IgG (day 0) and for five days afterwards (+5). A postoperative morbidity index (PMI) was generated as a weighted sum of: worsening lung infiltrates (I); leukocytosis (L); pulmonary dysfunction (P); ventilator requirement (V); septic shock (S); renal (R), gastrointestinal (G), or hepatic (H) dysfunction; thrombocytopenia (T); and delirium (D). RESULTS: At day 0, all patients were refractory to major antibiotics, with morbidities of: 1-100%, L-93%, P-93%, V-60%, S-27%, R-67%, G-40%, H-13%, T-27%, and D-20%. Using regression analysis, IV-IgG administration was associated with a statistically significant fall in white blood count and improvement in PMI (p <0.006). Fourteen patients (93%) recovered uneventfully, and one patient (7%) died from progressive sepsis. No complications of IV-IgG therapy occurred. CONCLUSION: Given the high predicted mortality of PD/MF patients, these data suggest that IV-IgG is a safe and efficacious adjunct to antibiotics in this setting. Further studies, including a randomized trial and investigation of immunomodulatory mechanisms, seem indicated.

Adult↗
PubMed2004

Single versus multiple internal mammary artery grafting for coronary artery bypass: 15-year follow-up of a clinical practice trial.

BACKGROUND: The long-term clinical advantages of using routine multiple internal mammary artery (IMA) grafts for coronary artery bypass (CAB) are not clear. This study was designed to test the hypothesis that multiple IMA grafts would provide better 15-year outcomes when compared with single IMA and vein grafts. METHODS AND RESULTS: Between 1984 and 1987, 1067 consecutive patients undergoing isolated CAB were referred to 1 surgeon practicing primarily single and another surgeon maximizing multiple IMA grafts (clinical practice trial). A 207-patient subset with multiple IMAs underwent postoperative graft angiography at 1 to 32 weeks to define initial IMA patency. Patients were followed-up yearly, and the groups were analyzed as (I) surgical strategy (surgeon operating) (single=413 versus multiple=654), (II) ultimate operation performed (single=418 versus multiple=449), or (III) single versus multiple coronary systems revascularized with IMAs (single=490 versus multiple=377). Advantages of this study design were that an entire referral population was examined, multiple IMAs were applied to the entire spectrum of baseline patient risk, 15-year follow-up provided a complete prognostic picture, and the subgroups were potentially comparable at baseline. In all 3 analyses, single and multiple groups were statistically similar with respect to baseline, operative, and immediate postoperative variables. Early IMA patency was 98.5% (333/338 grafts patent), validating the quality of IMA procedures. Unadjusted and adjusted 15-year outcome analyses for I, II, and III for death, myocardial infarction, percutaneous coronary intervention, redo coronary bypass, and the composite of all events identified multiple versus single as a significant predictor of outcome for the composite end point in adjusted analysis III (hazard ratio=0.808; 95% CI, 0.689 to 0.948; P=0.009), because of a 5% to 10% absolute reduction in each of the outcome variables at 15 years. Moreover, >50% reduction in reoperation rate was observed at 15 years in every analysis. CONCLUSIONS: At 15-year follow-up, multiple IMA grafting was associated with a 19.2% adjusted risk reduction in death and cardiac events, caused by decreases in all adverse end points and fewer reoperations. These data indicate that the clinical advantages of maximizing IMA conduits are significant. Based on this information, it is suggested that multiple IMA grafting to 2 coronary systems should be applied liberally to patients with noncardiac risk profiles predictive of long-term survival.

Aged↗
PubMed2004

Video-assisted thoracoscopic transplantation of myoblasts into the heart.

PURPOSE: Currently, cells are transplanted into injured myocardium either through thoracotomy for open surgical delivery or through catheterization for endoventricular or intracoronary delivery; both methods have limitations. Open surgical delivery limits the potential patient population, whereas catheter-based delivery limits the ability to visualize the injection site and confirm delivery of the cells to the appropriate region. In this study, we examine the feasibility of cell transplantation into myocardium using a minimally invasive thoracoscopic approach. DESCRIPTION: Seven swine underwent thoracoscopic cell transplantation. Using a prototype injection device, approximately 10 million myoblasts were injected into the anterior, lateral, posterior, and apical regions of myocardium. Animals were recovered up to 7 days, and after euthanasia, hearts were explanted for histology. EVALUATION: All seven swine had successful delivery of myoblasts into the defined injection sites, as confirmed by analysis of an operative video, magnetic resonance imaging of iron-oxide-labeled cells, and histologic examination. CONCLUSIONS: Thoracoscopic cellular cardiomyoplasty is feasible and allows the surgeon the benefits of direct visualization of the cell injection while minimizing morbidity associated with open cell delivery.

Animals↗
PubMed2004

Right ventricular targeted gene transfer of a beta-adrenergic receptor kinase inhibitor improves ventricular performance after pulmonary artery banding.

OBJECTIVE: Abrupt increases in right ventricular afterload occur after cardiac transplantation and pulmonary artery banding, which can result in right ventricular hypertrophy and dilatation. Right ventricular dysfunction is also accompanied by beta-adrenergic receptor desensitization. We sought to determine whether selective right ventricular expression of a transgene encoding a beta-adrenergic receptor kinase inhibitor can improve right ventricular remodeling early after pulmonary artery banding. METHODS: Rabbits underwent pulmonary artery banding 3 days after percutaneous right coronary artery injection of empty adenovirus (n = 19), a control adenovirus containing the beta-galactosidase transgene (n = 10), or an adenovirus containing the beta-adrenergic receptor kinase inhibitor transgene (n = 14). Sham-operated animals (n = 7) underwent instrumentation without deployment of the pulmonary artery band. Right ventricular function was assessed in each rabbit before and 7 days after pulmonary artery banding. Right ventricular mass and dimensions (surface area and volume) were obtained, and biochemical analysis was performed to confirm transgene expression and to characterize beta-adrenergic receptor signaling. RESULTS: Right ventricular mass was increased in animals treated with adenovirus containing the beta-adrenergic receptor kinase inhibitor transgene, adenovirus containing the beta-galactosidase transgene, and empty adenovirus after banding when compared with results in sham-operated animals. However, right ventricular volume and surface area, as measures of dilatation, were significantly lower in pulmonary artery banded rabbits pretreated with adenovirus containing the beta-adrenergic receptor kinase inhibitor transgene when compared with those treated with empty adenovirus or adenovirus containing the beta-galactosidase transgene. Right ventricular contractility and defective beta-adrenergic receptor signaling were significantly enhanced in rabbits expressing the beta-adrenergic receptor kinase inhibitor after pulmonary artery banding. CONCLUSIONS: Right ventricular preconditioning with the beta-adrenergic receptor kinase inhibitor transgene can attenuate the early right ventricular dilatation and dysfunction associated with pulmonary artery banding. Thus beta-adrenergic receptor kinase inhibition might represent a novel target for limiting ventricular remodeling after increased right ventricular afterload.

Adenoviridae↗
PubMed2004

Several new considerations in mitral valve repair.

BACKGROUND AND AIM OF THE STUDY: A retrospective evaluation was made of a small personal series of patients undergoing mitral valve repair in order to address four contemporary questions: (i) What is the best method of achieving a stable repair in mitral valve prolapse?; (ii) How should patients with pure annular dilatation without prolapse or antecedent ischemia be categorized?; (iii) Are valve procedures in ischemic mitral regurgitation (MR) still associated with less satisfactory early and late outcomes?; and (iv) Is prophylactic amiodarone therapy safe and effective in reducing postoperative arrhythmias? METHODS: Between 1993 and 2002, a total of 118 patients with non-rheumatic MR undergoing isolated mitral valve repair with or without coronary bypass was analyzed retrospectively: of these patients, 66 had prolapse (Group I), 21 had pure annular dilatation (Group II), and 31 had ischemic MR (Group III). All three groups routinely underwent Carpentier ring annuloplasty. Twenty-three patients in Group I were managed with leaflet resection and reconstruction (LRR), but in 1996 the technique for Group I was changed to uniform artificial chordal replacement (ACR) and no leaflet resection (n = 43). Also in 1996, prophylactic amiodarone therapy was first used routinely, and postoperative arrhythmia data were compared to those from prior patients. Baseline and outcome variables were assessed for each group and compared between the three groups. Survival data were evaluated using the Cox proportional hazards model. RESULTS: Significant differences in baseline characteristics were observed: Group II was predominantly female; Group III more often experienced acute presentation; and Groups II and III had more comorbid disorders and left ventricular dysfunction (all p < 0.01). ACR was highly successful for repair of prolapse, and no ACR patient exhibited significant residual MR or outflow tract obstruction. Operative mortality and morbidity were low in all groups, and ischemic etiology failed to be an independent predictor of early or late adverse outcome (p > 0.10). Cox model analysis to nine years of follow up (median 4 years) identified only advanced age and number of comorbidities as influencing late mortality (both p < 0.03). Over the follow up period, 8.7% of LRR patients required reoperation for valve failure due to late chordal rupture, whereas none of the ACR patients failed. Finally, prophylactic amiodarone significantly reduced postoperative arrhythmias (p = 0.03) with no observed complications, and also eliminated death due to arrhythmia. CONCLUSION: Ischemic etiology may be diminishing as an independent risk factor in Group III, at least partially because of uniform valve repair. Group II comprised a distinct entity of females with higher comorbidity, and prophylactic amiodarone therapy seemed useful as a routine measure. Finally, ACR appeared to produce a stable repair in virtually all Group I patients, suggesting that prolapse might be appropriately managed with ring annuloplasty and uniform ACR. However, future studies are suggested for further consideration of these hypotheses.

Aged↗
PubMed2003

RV instantaneous intraventricular diastolic pressure and velocity distributions in normal and volume overload awake dog disease models.

Intraventricular diastolic right ventricular (RV) flow field dynamics were studied by functional imaging using three-dimensional (3D) real-time echocardiography with sonomicrometry and computational fluid dynamics in seven awake dogs at control with normal wall motion (NWM) and RV volume overload with diastolic paradoxical septal motion. Burgeoning flow cross section between inflow anulus and chamber walls induces a convective pressure rise, which represents a "convective deceleration load" (CDL). High spatiotemporal resolution dynamic pressure and velocity distributions of the intraventricular RV flow field revealed time-dependent, subtle interactions between intraventricular local acceleration and convective pressure gradients. During the E-wave upstroke, the total pressure gradient along intraventricular flow is the algebraic sum of a pressure decrease contributed by local acceleration and a pressure rise contributed by a convective deceleration that partially counterbalances the local acceleration gradient. This underlies the smallness of early diastolic intraventricular gradients. At peak volumetric inflow, local acceleration vanishes and the total adverse intraventricular gradient is convective. During the E-wave downstroke, the strongly adverse gradient embodies the streamwise pressure augmentations from both local and convective decelerations. It induces flow separation and large-scale vortical motions, stronger in NWM. Their dynamic corollaries on intraventricular pressure and velocity distributions were ascertained. In the NWM pattern, the strong ring-like vortex surrounding the central core encroaches on the area available for flow toward the apex. This results in higher linear velocities later in the downstroke of the E wave than at peak inflow rate. The augmentation of CDL by ventriculoannular disproportion may contribute to E wave and E-to-A ratio depression with chamber dilatation.

Animals↗