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Donald D Glower

Publications and source records attributed to Donald D Glower.

35 records · Page 2Linked to original sources
PubMed2003

Survival after coronary revascularization, with and without mitral valve surgery, in patients with ischemic mitral regurgitation.

BACKGROUND: The most appropriate treatment for patients with ischemic mitral regurgitation (IMR) is often debated. We compared the survival rates of patients with IMR undergoing different treatment strategies, namely: medical therapy, percutaneous coronary intervention (PCI), coronary artery bypass grafting (CABG), and CABG + mitral valve (MV) surgery. METHODS AND RESULTS: Patients undergoing catheterization between 1986 and 2001 were included. IMR was defined as: >or=grade 2+ mitral regurgitation (MR) and significant coronary artery disease (CAD) without primary mitral valve disease. Patients undergoing catheterization for the evaluation of congenital or other valvular heart disease were excluded. Multivariable Cox proportional hazards modeling was utilized to assess the independent relation between treatment and survival. Propensity score methods were used to correct for the nonrandom assignment of treatment. Of the 2,757 patients who met study criteria: 1,305 were treated medically, 537 underwent PCI, 687 underwent CABG, and 228 underwent CABG + MV surgery. The median duration of follow-up was 3.2 (0.9, 7.1) years. Patients undergoing CABG + MV surgery had more severe MR and more severe heart failure than those treated by other modalities. After adjusting for differences in baseline characteristics, patients undergoing PCI, CABG, and CABG + MV surgery had a 31% (hazards ratio [HR]=0.69; P=0.0001), 42% (HR=0.58; P=0.0001), and 42% (HR=0.58; P=0.0001) reduction in the risk of death, respectively, compared with those undergoing medical therapy. The performance of mitral valve surgery with CABG was not associated with improved survival versus CABG alone (P=0.258). CONCLUSIONS: Among patients with IMR, treatment with PCI, CABG, or CABG + MV surgery is associated with improved survival compared with medical therapy.

Aged↗
PubMed2003

Mitral valve surgery and acute renal injury: port access versus median sternotomy.

BACKGROUND: Many outcomes and complications of minimally invasive and conventional cardiac surgery await comparison. Patients undergoing mitral valve surgery commonly sustain renal injury. Using peak postoperative fractional change of serum creatinine as a marker of renal injury, we tested the hypothesis that mitral valve surgery with port access minithoracotomy (Port) and conventional surgery with a median sternotomy (MS) incision are associated with different degrees of acute renal injury. METHODS: We evaluated data from all isolated mitral valve operations by a single surgeon between 1990 and 2000 (MS = 90, Port = 227). We also performed a secondary analysis of mitral valve surgeries performed by both MS and Port approaches in a concurrent period from 1996 to 2002 (MS = 93, Port = 240). Univariable and multivariable tests were used to determine the association of surgical technique with peak postoperative creatinine (CrmaxPost) and peak postoperative fractional change in creatinine (%deltaCr); p less than 0.05 was considered significant. RESULTS: In our analysis that accounted for the date of surgery, we observed a highly significant independent association between surgical approach and %deltaCr, indicating a greater risk of acute renal injury in the MS group (F value 13.33; p = 0.0003). Similar findings were noted in the secondary (time-concurrent) analysis of %deltaCr (F value 12.65; p = 0.0176). CONCLUSIONS: We present retrospective evidence of reduced acute renal injury associated with the port access technique in mitral valve surgery patients. Our findings suggest that a port access minithoracotomy approach to mitral valve surgery may be preferable to conventional methods for patients with high renal risk.

Acute Kidney Injury↗
PubMed2003

Real-time three-dimensional echocardiography to construct clinically ready, load-independent indices of myocardial contractile performance.

BACKGROUND: Real-time 3-dimensional echocardiography (RT3DE) reliably determines intracardiac chamber volumes without left ventricular (LV) geometric assumptions, yet clinical assessment of contractile performance is often on the basis of potentially inaccurate, load-dependent indices such as ejection fraction. METHODS: In 6 chronically instrumented dogs, RT3DE estimated LV volumes at various loading conditions. Preload recruitable stroke work and end-systolic pressure-volume relationships were constructed. RT3DE-derived indices were compared with similar relationships determined by sonomicrometry. RESULTS: Highly linear preload recruitable stroke work and end-systolic pressure-volume relationships were constructed by RT3DE and sonomicrometry. Mean preload recruitable stroke work slopes correlated between methods, but volume intercepts differed as a result of geometric assumptions of sonomicrometry. Conversely, RT3DE-derived end-systolic pressure-volume relationships did not correlate well with sonomicrometry. CONCLUSIONS: These data are unique in reporting load-independent measures of LV performance using RT3DE. These techniques would strengthen evaluation of LV function after myocardial ischemia or cardiac operation, in which frequent changes in ventricular geometry or loading conditions confound functional assessment by more traditional methods.

Animals↗
PubMed2003

The effects of acute afterload change on systolic ventricular function in conscious dogs with normal vs. failing hearts.

BACKGROUND: To date, no data exist on the linearity and, therefore, the usefulness of the preload recruitable stroke work (PRSW) and end-systolic pressure-volume (ESPVR) relationships during acute afterload changes in heart failure. AIMS: Our aim was, therefore, to characterize both relationships in a model of ventricular pacing induced heart failure at baseline and during acute changes in afterload. METHODS: Dynamic left ventricular volume and transmural pressure were measured in 10 conscious dogs using sonomicrometry and micromanometry under control conditions and during heart failure produced by 3 weeks of rapid right ventricular pacing. Afterload was varied from baseline with intravenous infusions of nitroprusside and phenylephrine. Left ventricular function was assessed using the PRSW and ESPVR relationships. RESULTS: Cardiac output demonstrated a linear inverse relationship with afterload in both normal and failing hearts (r2>0.5, P<0.001) with failure producing a parallel, downward shift of the afterload (x) vs. cardiac output (y) relationship (P<0.01). Yet, afterload variation did not affect PRSW or ESPVR relationships in either normal or failing hearts (r2<0.12, P>0.05). CONCLUSION: Thus, the PRSW and ESPVR relationships are insensitive to acute afterload changes in both failing and normal hearts, and the failing left ventricle is no more afterload-sensitive than the normal heart.

Animals↗
PubMed2003

Catheter-based intracoronary myocardial adenoviral gene delivery: importance of intraluminal seal and infusion flow rate.

Although percutaneous, adenoviral-mediated intracoronary gene delivery to the heart has been demonstrated in some species, consistent and safe methodology is needed before clinical applicability is possible. In this study, we examine the effects of altering intracoronary flow rate and obtaining an adequate seal between the catheter and the coronary lumen on successful cardiac gene delivery and myocardial injury in both piglets and adult rabbits. To study the efficacy of in vivo myocardial gene transfer, we utilized adenoviral vectors containing either the beta(2)-adrenergic receptor or beta-galactosidase. The left circumflex coronary artery of piglets and the right coronary artery of rabbits were catheterized under fluoroscopic guidance and adenovirus solutions were injected using varying flow rates with or without balloon inflation. Successful transgene delivery to the heart was determined approximately 1 week after coronary infusions. Histologic analysis was also performed in all animals to determine the extent of myocardial injury. Our results indicate that efficient and reproducible cardiac transgene expression utilizing intracoronary delivery is dependent upon the infusion flow rate and, in larger animals, requires an intraluminal seal. Excessive flow rate is associated with greater myocardial injury. Thus, conditions can be established and controlled to improve future investigational and clinical application of catheter-based intracoronary myocardial gene therapy.

Adenoviridae↗
PubMed2003

Lung isolation during port-access cardiac surgery: double-lumen endotracheal tube versus single-lumen endotracheal tube with a bronchial blocker.

OBJECTIVE: The purpose of this study was to compare the use of a double-lumen endotracheal tube to a single-lumen tube combined with a bronchial blocker for lung isolation during Port-Access cardiac surgery. DESIGN: Prospective, randomized, controlled trial. SETTING: Tertiary care university hospital. PARTICIPANTS: Thirty-two patients undergoing Port-Access cardiac surgery via a right minithoracotomy. INTERVENTIONS: Patients were randomized to intubation with either a left-sided double-lumen tube (double-lumen group) or a single-lumen tube with concomitant use of a bronchial blocker (blocker group). Comparisons between groups included (1) intubation time, (2) number of laryngoscopy attempts, (3) time required for tube exchange at the end of the operation, and (4) surgical satisfaction with the lung deflation (1-5 scale: 5 = excellent). MEASUREMENTS AND MAIN RESULTS: The initial intubation time was similar between groups (118 +/- 82 seconds, double-lumen v 144 +/- 32 seconds, blocker; p = 0.2781). An additional 105 +/- 37 seconds was needed to exchange the double-lumen tube at the end of the operation. The double-lumen group also required more laryngoscopy attempts compared with the blocker group (2.3 +/- 0.6, double-lumen v 1.1 +/- 0.4, blocker; p = 0.0001). The lung deflation was better in the double-lumen group (5 [4-5], double-lumen v 4 [3-5], blocker, p = 0.0414). CONCLUSIONS: Compared with a single-lumen tube/bronchial blocker combination the double-lumen endotracheal tube required more laryngoscopy attempts and additional time to replace the tube at the end of the case but resulted in slightly better overall lung deflation.

Bronchi↗
PubMed2003

Diastolic right ventricular filling vortex in normal and volume overload states.

Functional imaging computational fluid dynamics simulations of right ventricular (RV) inflow fields were obtained by comprehensive software using individual animal-specific dynamic imaging data input from three-dimensional (3-D) real-time echocardiography (RT3D) on a CRAY T-90 supercomputer. Chronically instrumented, lightly sedated awake dogs (n = 7) with normal wall motion (NWM) at control and normal or diastolic paradoxical septal motion (PSM) during RV volume overload were investigated. Up to the E-wave peak, instantaneous inflow streamlines extended from the tricuspid orifice to the RV endocardial surface in an expanding fanlike pattern. During the descending limb of the E-wave, large-scale (macroscopic or global) vortical motions ensued within the filling RV chamber. Both at control and during RV volume overload (with or without PSM), blood streams rolled up from regions near the walls toward the base. The extent and strength of the ring vortex surrounding the main stream were reduced with chamber dilatation. A hypothesis is proposed for a facilitatory role of the diastolic vortex for ventricular filling. The filling vortex supports filling by shunting inflow kinetic energy, which would otherwise contribute to an inflow-impeding convective pressure rise between inflow orifice and the large endocardial surface of the expanding chamber, into the rotational kinetic energy of the vortical motion that is destined to be dissipated as heat. The basic information presented should improve application and interpretation of noninvasive (Doppler color flow mapping, velocity-encoded cine magnetic resonance imaging, etc.) diastolic diagnostic studies and lead to improved understanding and recognition of subtle, flow-associated abnormalities in ventricular dilatation and remodeling.

Animals↗
PubMed2002

RV functional imaging: 3-D echo-derived dynamic geometry and flow field simulations.

We describe a novel functional imaging approach for quantitative analysis of right ventricular (RV) blood flow patterns in specific experimental animals (or humans) using real-time, three-dimensional (3-D) echocardiography (RT3D). The method is independent of the digital imaging modality used. It comprises three parts. First, a semiautomated segmentation aided by intraluminal contrast medium locates the RV endocardial surface. Second, a geometric scheme for dynamic RV chamber reconstruction applies a time interpolation procedure to the RT3D data to quantify wall geometry and motion at 400 Hz. A volumetric prism method validated the dynamic geometric reconstruction against simultaneous sonomicrometric canine measurements. Finally, the RV endocardial border motion information is used for mesh generation on a computational fluid dynamics solver to simulate development of the early RV diastolic inflow field. Boundary conditions (tessellated endocardial surface nodal velocities) for the solver are directly derived from the endocardial geometry and motion information. The new functional imaging approach may yield important kinematic information on the distribution of instantaneous velocities in the RV diastolic flow field of specific normal or diseased hearts.

Animals↗
PubMed2002

Minimally invasive tricuspid operation using port access.

BACKGROUND: Port-access techniques performed through a right mini-thoracotomy have been extensively described for both the mitral and aortic valves. However, reports of tricuspid valve operations using the port-access approach are rare. A technique for minimally invasive tricuspid valve operation using port access is described. METHODS: Port-access approach was applied to 33 consecutive patients undergoing tricuspid valve repair or replacement. RESULTS: Twelve percent (4 of 33) underwent tricuspid replacement and 88% underwent repair (28 of 33). Perioperative mortality was 6% (2 of 33) and conversion to median sternotomy was 3% (1 of 33). CONCLUSIONS: Port-access tricuspid operations are both feasible and safe with a low conversion rate to conventional median sternotomy.

Aged↗
PubMed2002

Mitral surgery after prior cardiac operation: port-access versus sternotomy or thoracotomy.

BACKGROUND: In reoperation for mitral valve disease, minimally invasive Port-Access (PORT) is a new alternative to standard median sternotomy (STER) or right thoracotomy (THOR); yet, the results of PORT in this setting have not been defined. The aim of this study was to evaluate the results of minimally invasive thoracotomy in reoperation for mitral valve disease. METHODS: Retrospective results are reported for three consecutive series of patients undergoing reoperation for mitral disease using either PORT (n = 60, 1996 to 2001), THOR (n = 37, 1985 to 1997), or STER (n = 155, 1985 to 1997). RESULTS: Red cell transfusion was 3 +/- 4, 14 +/- 13, and 12 +/- 12 units for PORT, THOR, and STER, respectively. Chest tube output was 352 +/- 361, 2048 +/- 3166, and 1683 +/- 3939 mL, respectively. Cardiopulmonary bypass times for these groups were 208 +/- 76 vs. 158 +/- 56 vs. 157 +/- 53 minutes. Thirty-day mortality was 0/60 (0%), 8/37 (22%), and 21/155 (14%), respectively. CONCLUSIONS: This early clinical experience suggests that PORT is an acceptable alternative to THOR or STERN in reoperation for mitral valve disease, with potential advantages of avoiding redo sternotomy and reducing the surgical incision. However, these benefits may come at the expense of longer cardiopulmonary bypass times.

Cardiac Surgical Procedures↗
PubMed2002

Right ventricular diastolic relaxation in conscious dog models of pressure overload, volume overload, and ischemia.

OBJECTIVE: Limitations in clinical understanding of right ventricular relaxation can be attributed to the paucity of information from basic studies in animal models of right ventricular disease. This study examined, in the conscious state, right ventricular relaxation dynamics under normal conditions (n = 15) and in subacute (2-5 weeks) canine models of right ventricular pressure overload (n = 6), volume overload (n = 7), and free wall ischemia (n = 7). METHODS: Right-heart micromanometric measurements were obtained by using multisensor catheters. A new algorithm was developed to obtain representative ensemble averages of hemodynamic waveform data sets. Right ventricular relaxation was analyzed by using an exponential model with 3 parameters: P(0), tau, and P(b). Significant changes versus control values were determined by means of analysis of variance and the Student unpaired t test with Bonferroni's adjustment. RESULTS: In the state of pressure overload, right ventricular pressure decay exhibits an increased P(0) (56.2 +/- 19.1 vs 13.1 +/- 5.1 mm Hg [mean +/- SD]) and prolonged tau (57.1 +/- 2.8 vs 27.8 +/- 3.9 ms); there is also a decreased P(b) (-7.9 +/- 1.5 vs 0.28 +/- 1.8 mm Hg). The only significant change in volume overload is an increased asymptote, P(b) (5.3 +/- 2.9 mm Hg). In right ventricular ischemia, prolongation of tau (41.4 +/- 13.0 ms) and decreased P(b) (-1.95 +/- 1.1 mm Hg) attain high significance. CONCLUSIONS: Distinctive abnormalities in right ventricular relaxation dynamics accompany pressure overload, volume overload, and ischemia and may contribute to clinical right ventricular dysfunction.

Animals↗
PubMed2002

Right ventricular diastolic function in canine models of pressure overload, volume overload, and ischemia.

By limiting filling, abnormalities of right ventricular (RV) diastolic function may impair systolic function and affect adaptation to disease. To quantify diastolic RV pressure-volume relations and myocardial compliance (MC), a new sigmoidal model was developed. RV micromanometric and sonomicrometric data in alert dogs at control (n = 16) and under surgically induced subacute (2-5 wk) RV pressure overload (n = 6), volume overload (n = 7), and ischemia (n = 6) were analyzed. The conventional exponential model detected no changes from control in the passive filling pressure-volume (P(pf)-V) relations. The new sigmoidal model revealed significant quantifiable changes in P(pf)-V relations. Maximum RV MC (MC(max)), attained during early filling, is reduced from control in pressure overload (P = 0.0016), whereas filling pressure at maximum MC (P(MCmax)) is increased (P = 0.0001). End-diastolic RV MC increases significantly in volume overload (P = 0.0131), whereas end-diastolic pressure is unchanged. In ischemia, MC(max) is decreased (P = 0.0102), with no change in P(MCmax). We conclude that the sigmoidal model quantifies important changes in RV diastolic function in alert dog models of pressure overload, volume overload, and ischemia.

Animals↗
PubMed2002

Comparison of port access to sternotomy in tricuspid or mitral/tricuspid operations.

BACKGROUND: Outcomes for a port-access (PA) approach for tricuspid valve operations have not been reported or compared to those using median sternotomy (MS). METHODS: Retrospective analysis was performed for 88 consecutive patients undergoing tricuspid valve repair or replacement using port-access techniques (n = 27, 1997-2000) versus sternotomy (n = 61, 1990-1997). PA procedures were performed through a 6 cm right fourth interspace thoracotomy. RESULTS: PA patients had lower ejection fractions (46% +/- 11% vs. 54% +/- 10%, p = 0.02), but had a similar incidence of previous surgery (17/27 (63%) vs. 33/61 (54%), p = 0.4). PA patients had more frequent concurrent mitral valve operations (22/27 (82%) vs. 37/61 (61%), p <0.05) and more tricuspid repairs versus replacement (24/27 (89%) vs. 29/61 (48%), p <0.01). PA patients had longer pump times (254 min. +/- 82 vs. 162 min. +/- 61, p = 0.001) but comparable clamp times (65 min. +/- 15 vs. 63 min. +/- 41, p = 0.9), lengths of stay (14 days +/- 14 vs. 16 days +/- 16, p = 0.6), mortality (2/27 (7%) vs. 9/61 (15%), p = 0.3), strokes (3/27 (11%) vs. 4/59 (7%), p = 0.9), and need for new pacemaker implantation (5/27 (19%) vs. 12/61 (20%), p = 0.9). CONCLUSIONS: PA provided excellent short-term results comparable to MS in relatively high-risk tricuspid valve patients. For tricuspid operations, PA may have the advantage of avoiding sternotomy or reoperative sternotomy at the expense of longer pump times.

Female↗