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Biomedical subjects

Thoralf M Sundt

Publications and source records attributed to Thoralf M Sundt.

At least 19 recordsLinked to original sources
PubMed2004

Noninvasive, quantitative assessment of left ventricular function in ischemic cardiomyopathy.

BACKGROUND: Coronary artery disease characteristically impacts left ventricular (LV) function on a regional basis, although ultimately global function may be affected as well. Echocardiography is commonly clinically used for the assessment of regional function; however, it is only semiquantitative and in its current iteration is only two-dimensional in nature. Magnetic resonance imaging (MRI) with tissue tagging offers the possibility for noninvasive, three-dimensional (3D) assessment of transmural and segmental left ventricular strain and, thereby, function. Accordingly, we have explored methodologies to accurately and quantitatively characterize regional systolic function in three dimensions in patients with ischemic heart disease using MRI. MATERIALS AND METHODS: MRI radiofrequency tissue tagging was performed at rest and during dobutamine administration (10 mg/kg/min) on 10 normal volunteers (age: 26 +/- 6) and 8 patients with severe ischemic cardiomyopathy (age: 60 +/- 5, EF 26 +/- 11%). Three-dimensional global and regional systolic strain calculations were made based on 3D myocardial point displacements and compared with conventional measures. RESULTS: Global left ventricular strains were significantly decreased in ischemic patients at rest (0.14 +/- 0.04 versus 0.25 +/- 0.02, P < 0.001) and with dobutamine (0.14 +/- 0.03 versus 0.29 +/- 0.03, P < 0.001). In the regional analysis (216 LV wall segments) this methodology accurately differentiated normal from abnormally contracting regions. CONCLUSIONS: Noninvasive dobutamine MRI tissue tagging with calculation of 3D regional strains has significant promise as a clinical tool which is capable of the identification, quantification, and display of regionally varying ventricular function.

Aged↗
PubMed2003

Trends in the surgical management of ischemic mitral regurgitation.

The surgical approach to ischemic mitral regurgitation (IMR) remains a topic of considerable controversy. Will coronary artery bypass alone suffice, or should the valve be intervened upon? The poor late survival of patients with IMR is well recognized, but it remains unknown if this can be altered by addressing the valve directly. And if surgery is undertaken, should the valve be repaired or replaced? The underlying mechanisms of IMR remain incompletely understood, and although current theory focuses on the role of alterations in ventricular geometry in its pathogenesis, IMR is most often addressed by annuloplasty alone. Is this sufficient, or does the ventricle itself require "remodeling?" The debate is confounded by imprecise terminology that fails to distinguish between acute and chronic disease, and active ischemia from completed infarction. Available clinical information is from retrospective studies with all of their inherent limitations and potential for bias. Still, progress is being made as increasing attention is focused on this clinically important entity.

Cardiac Surgical Procedures↗
PubMed2003

Delayed paraplegia after thoracic and thoracoabdominal aneurysm repair: a continuing risk.

BACKGROUND: Paraplegia or paraparesis after otherwise successful thoracic or thoracoabdominal aortic reconstruction is a devastating complication for patient and physician. Interventions for its prevention have focused primarily on the intraoperative period. We have recently noted a significant incidence of delayed-onset neurologic deficit. METHODS: We reviewed our most recent 5-year experience with thoracic and thoracoabdominal reconstruction to examine the incidence of and potential contributors to delayed paraplegia or paraparesis. RESULTS: Between June 1996 and June 2001, 60 patients (29 men, 31 women) underwent repair of isolated thoracic (n = 26) or thoracoabdominal aortic aneurysm (Crawford I, n = 7; Crawford II, n = 14; Crawford III, n = 12; Crawford IV, n = 1) by the cardiac and vascular surgical services collaboratively. Repair was performed endovascularly in 6, and open with either circulatory arrest in 12, partial left heart bypass in 37, or partial femorofemoral bypass in 5. Operative mortality was 9.3% (5 of 54 patients) for open repair and 0% for endovascular repair. Paraplegia or paraparesis occurred in 6 (10%) patients of which 83.3% (5 of 6) were delayed in onset. All patients with delayed paraplegia or paraparesis had degenerative aneurysms of Crawford extent II (n = 3) or III (n = 2), had intraoperative left heart bypass, and had perioperative spinal drainage. Delayed paraplegia or paraparesis occurred up to 27 days postoperatively, and was associated with a documented episode of hypotension in 60% (3 of 5) of patients. CONCLUSIONS: Improvements in intraoperative management may have reduced immediate paraplegia or paraparesis among vulnerable patients only to leave them at risk of delayed-onset deficit. Postoperative care, including assiduous attention to avoidance of even transient hypotension, must be tailored to this patient population.

Adult↗
PubMed2003

Altered patterns of gene expression distinguishing ascending aortic aneurysms from abdominal aortic aneurysms: complementary DNA expression profiling in the molecular characterization of aortic disease.

OBJECTIVES: The purpose of this study was to profile altered patterns of gene expression that characterize degenerative ascending thoracic aortic aneurysms and to compare these patterns with those observed for infrarenal abdominal aortic aneurysms. METHODS: Full-thickness aortic wall tissues were obtained during surgical repair of degenerative thoracic aortic aneurysms and infrarenal abdominal aortic aneurysms (n = 4 each), with normal thoracic and abdominal aortas from organ transplant donors used as control preparations. Radiolabeled complementary DNA was prepared for each specimen and hybridized to complementary DNA microarrays, and differential levels of gene expression between aneurysmal and normal aortic tissues at each site were assessed by parametric statistics. RESULTS: Of 1185 genes examined, 112 (9.5%) were differentially expressed (P <.05) between thoracic aortic aneurysms and normal thoracic aorta, with 105 increased and 7 decreased. There were 104 genes (8.8%) differentially expressed between infrarenal abdominal aortic aneurysms and normal abdominal aorta (65 increased and 39 decreased). Quantitative increases in expression for 97 genes were unique to thoracic aortic aneurysms, whereas increases for 61 genes were unique to infrarenal abdominal aortic aneurysms. Although 8 gene products were significantly altered in both thoracic and infrarenal abdominal aortic aneurysms, these changes were directionally concordant for only 4 (matrix metalloproteinase 9/gelatinase B, v-yes-1 oncogene, mitogen-activated protein kinase 9, and intercellular adhesion molecule 1/CD54). Results for 9 genes were independently confirmed by quantitative reverse transcriptase-polymerase chain reaction. CONCLUSIONS: Thoracic aortic aneurysms and infrarenal abdominal aortic aneurysms exhibit distinct patterns of gene expression relative to normal aorta from the same sites, with most alterations being unique to each disease. Degenerative aneurysms arising in different locations are thus characterized by a high degree of molecular heterogeneity, reflecting different pathophysiologic mechanisms.

Adolescent↗
PubMed2003

Risk factors for leg harvest surgical site infections after coronary artery bypass graft surgery.

OBJECTIVE: Harvest site infections are more common than chest surgical infections after coronary artery bypass surgery, yet few studies detail risk factors for these infections. We sought to determine independent risk factors for leg surgical site infections using our institutional Society of Thoracic Surgeons database. METHODS: We retrospectively analyzed data collected from 1980 coronary artery bypass patients undergoing surgery at our institution from January 1, 1996, through June 30, 1999, using The Society of Thoracic Surgeons database. Independent risk factors for leg harvest site infection were identified by multivariate logistic regression. RESULTS: Seventy-six patients (4.5%) were coded as having had a leg harvest site infection, of which 67 were confirmed by infection control. The length of hospital stay after surgery was significantly longer in patients with leg harvest site infection (mean 10.1 days) compared with that of patients without infection (mean 7.1 days, P <.001), and infected patients were more likely to be readmitted to the hospital within 30 days of surgery. Independent risk factors for leg harvest site infection included previous cerebrovascular accident (odds ratio, 2.9), postoperative transfusion of 5 units or more of red blood cells (odds ratio, 2.8), obesity (odds ratio, 2.5), age 75 years or older (odds ratio, 1.9), and female gender (odds ratio, 1.8). CONCLUSIONS: Consistent with previous studies, female gender and obesity were identified as independent risk factors for leg harvest site infection, while previous cerebrovascular accident, postoperative transfusion, and older age are newly described risk factors. The Society of Thoracic Surgeons database is a useful tool for identification of predictors of leg harvest site infections.

Age Factors↗
PubMed2003

The influence of mechanical properties on wall stress and distensibility of the dilated ascending aorta.

OBJECTIVES: We sought to determine how intrinsic mechanical properties of dilated ascending aorta influence in vivo distensibility and wall stress, potential contributing factors to the risk of aortic rupture and dissection. METHODS: Fresh tissue from patients undergoing ascending aortic replacement for Marfan syndrome (n = 8, age 38 +/- 14 years), bicuspid aortic valve with associated aneurysm (n = 20, age 55 +/- 12 years), or idiopathic degenerative aneurysm (n = 7, age 64 +/- 9 years) was analyzed for elastic properties and circumferential residual stress. Histologic specimens were graded for elastin fragmentation, cystic changes, fibrosis, and necrosis. Distensibility and wall stresses were predicted with a cylindrical mathematical model of the aorta. RESULTS: Elastic properties of aortic tissue were nonlinear and extensibility decreased with age. Moderate or severe elastin fragmentation was prevalent in tissue from patients with the Marfan syndrome and more common in tissue from younger patients. Model-predicted mean circumferential stress did not vary significantly with age or patient group, but increased with aortic lumen diameter and systolic blood pressure. Model-predicted distensibility decreased with age in bicuspid aortic valve and degenerative aneurysm groups. Differences in distensibility were correlated with differences in elastic properties. CONCLUSIONS: The age dependence of elastic properties of dilated ascending aorta is consistent with that of normal aorta observed in previous studies. Increases in mean circumferential stress with blood pressure and diameter support the clinical importance of blood pressure control and serial evaluation of aortic diameter. Declining wall strength with age may increase the risk of rupture or dissection.

Adolescent↗
PubMed2003

The Cox maze III procedure for atrial fibrillation: long-term efficacy in patients undergoing lone versus concomitant procedures.

BACKGROUND: For the last decade, the Cox maze III procedure has been available for the treatment of atrial fibrillation. It is unknown whether the operation has similar efficacy in patients with lone atrial fibrillation compared with that in patients with atrial fibrillation associated with coronary, valve, or congenital heart disease. This study examined the long-term outcome of patients who underwent this procedure either as a lone operation or as a concomitant procedure. METHODS: From 1988 to 2001, 198 patients underwent a Cox maze III procedure; 112 were lone operations, and 86 were concomitant procedures. Major complications included renal failure, reoperation for bleeding, mediastinitis, stroke, and balloon pump insertion. Follow-up was performed by means of mail and telephone questionnaires with both the patients and their cardiologists. All patients who had any history of arrhythmia or who were taking medication had their rhythm documented by means of electrocardiography. RESULTS: The lone operation group was significantly younger (51.3 +/- 10.5 vs 58.8 +/- 9.9 years) and had a higher male/female ratio (4:1 vs 2:1). There was no difference in operative mortality between groups (1.8% vs 1.2%). At a follow-up of 5.4 +/- 2.9 years, 96.6% (172/178) of all patients were free of atrial fibrillation. There was no difference between the lone operation and concomitant procedure groups (95.9% vs 97.5%). CONCLUSION: The Cox maze III procedure has equivalent operative risk and long-term efficacy in patients undergoing both lone operations and concomitant procedures. The Cox maze III procedure remains the standard against which alternative procedures for atrial fibrillation must be judged.

Adult↗
PubMed2003

Irrigated bipolar radiofrequency ablation with transmurality feedback for the surgical Cox-Maze procedure.

BACKGROUND: Nonirrigated radiofrequency ablation (RFA) has been used to replicate the surgical scars of the Cox-Maze procedure. This study aimed to demonstrate that an irrigated, bipolar RFA energy source could also effectively replicate Cox-Maze lesions with impedance monitoring to predict the transmurality of ablated tissue. METHODS: A complete Cox-Maze lesion pattern was created ex vivo on fresh porcine atria using an irrigated, bipolar RFA system. Tissues were clamped between opposing electrodes with steady pressure to ensure an intimate tissue-electrode interface during ablation. A proprietary feedback and control algorithm monitored tissue impedance and terminated ablation when lesions were deemed transmural by a plateau in impedance decline. Ablation time and power, lesion width and length, and tissue thickness were recorded. Lesions were stained with 1% triphenyltetrazolium chloride and sectioned for gross assessment of transmurality. RESULTS: One hundred thirty-seven lesions were created on 11 porcine hearts. The total ablation time per lesion was 14.8 +/- 1.2 seconds (range, 10.0-19.0 seconds). Lesions averaged 4.2 +/- 1.3 mm (range, 1.3-10.2 mm) in width. Average tissue thickness was 3.0 +/- 1.7 mm (range, 0.5-9.9 mm). Crosssectional examination revealed that 100% of lesions were transmural (n = 718), and no tissue defects were observed. CONCLUSIONS: These results indicate that irrigated bipolar RFA energy can produce transmural Cox-Maze lesions ex vivo on intact porcine atria and that impedance monitoring is a reliable predictor of lesion transmurality. Additional in vivo studies are under way to further demonstrate the efficacy and safety of irrigated, bipolar RFA technology.

Animals↗
PubMed2002

Altered left ventricular geometry changes the border zone temporal distribution of stress in an experimental model of left ventricular aneurysm: a finite element model study.

BACKGROUND: Left ventricular aneurysm (LVA) is a significant complication of myocardial infarction that may lead to global left ventricular (LV) dysfunction. However, the exact mechanism underlying the abnormal function has not been elucidated. In this study we tested the hypothesis that changes in LV geometry cause both an increase in wall stress and a change in the temporal distribution of stress in the LVA border zone (BZ) during systole. METHODS: Transmural anteroapical infarcts were created in adult Dorsett sheep (n=8) and were allowed to mature into LVAs for 10 weeks. Animals were imaged subsequently using MRI with simultaneous recording of intraventricular pressures. Cardiac models were constructed from the MRI images at end-diastole, isovolumic systole, peak-systole and end-systole. Two short-axis slices, 1 basal and 1 apical were analyzed. The apical slice included the septal and anterior component of the aneurysm as well as the corresponding BZs and normal myocardium. Regional wall stresses were calculated using finite element analysis and compared with stresses in corresponding regions from normal control sheep (n=7). RESULTS: In the LVA group, stress was significantly increased in the BZ at the end-diastolic, isovolumic, peak-systolic, and end-systolic instants (P<0.001 for all). In addition the temporal distribution of stress was significantly altered with maximum stress occurring at peak instead of isovolumic systole. CONCLUSIONS: Geometric changes in the LVA hearts increased wall stress and altered its temporal distribution in the BZ region. Correlation of this finding with the corresponding regional blood flow, oxygen consumption, and mechanical systolic performance may help elucidate the mechanism underlying the observed global LV dysfunction.

Animals↗
PubMed2002

Infective endocarditis resulting from CardioSEAL closure of a patent foramen ovale.

Patent foramen ovale and atrial septal aneurysm are associated with an increased risk of cryptogenic stroke and recurrent thromboembolic events. Percutaneous closure is a therapeutic option to medical therapy and surgical closure. We present the first case of endocarditis associated with a CardioSEAL device closing a patent foramen ovale.

Adult↗
PubMed2002

Lung transplantation for pulmonary vascular disease.

BACKGROUND: Pulmonary hypertension (PHT) is a lethal condition resulting in markedly diminished life expectancy. Continuous prostaglandin I2 infusion has made an important contribution to symptom management, but it is not a panacea. Lung or heart-lung transplantation remains an important treatment option for end-stage PHT patients unresponsive to prostaglandin I2. This study reviews the outcomes after transplantation for PHT in our program. METHODS: A retrospective chart review was performed for 100 consecutive patients with either primary PHT (48%) or secondary PHT (52%) transplants since 1989. Living recipients were contacted to confirm health and functional status. RESULTS: Fifty-five adult and 45 pediatric patients underwent 51 bilateral lung transplants, 39 single lung transplants, and 10 heart-lung transplants. Mean age was 23.7 years (range, 1.2 months to 54.8 years) and mean pre-transplant New York Heart Association class was 3.2. Pre-transplant hemodynamics revealed a mean right atrial pressure of 9.6+/-5.4 mm Hg and mean pulmonary artery pressure of 64+/-14.4 mm Hg. Hospital mortality was 17% with early death predominantly because of graft failure and infection. With an average follow-up of 5.0 years, 1- and 5-year actuarial survival was 75% and 57%, respectively. Mean pulmonary artery pressure on follow-up catheterization was 22+/-6.0 mm Hg, and mean follow-up New York Heart Association class was 1.3 (p < 0.001 for both compared with pre-transplant). Diagnosis and type of transplant did not confer a significant difference in survival between groups. CONCLUSIONS: Whereas lung or heart-lung transplant for PHT is associated with higher early mortality than other pulmonary disease entities, it provides similar long-term outcomes with dramatic improvement in both quality of life and physiologic aspects.

Adolescent↗
PubMed2002

Influence of retrograde cerebral perfusion during aortic arch procedures.

BACKGROUND: Recent reports suggest dramatic improvement in outcome using retrograde cerebral perfusion (RCP) during operations on the arch; however, most investigators have compared contemporary results with historic controls. The purpose of this study was to determine the impact of RCP within the same patient population and time period. METHODS: From 1996 to 2000, 72 consecutive patients underwent an aortic arch procedure using hypothermic circulatory arrest (HCA) (31 acute dissection or rupture, 41 chronic dissection or aneurysm). Supplemental RCP was used in 36 patients, whereas 36 patients had HCA alone. The groups were similar in age, emergent status, and cardiopulmonary bypass time (p > 0.08), but HCA time was higher with RCP (40 +/- 15 minutes versus 29 +/- 14 minutes; p < 0.001). RESULTS: Operative mortality was 10% +/- 4% (+/- 70% confidence limit), and adverse outcomes (death or cerebrovascular accident) occurred in 14% +/- 4%, but there was no difference between HCA alone (8% +/- 5%, 14% +/- 6%) and HCA with RCP (11% +/- 5%, 14% +/- 6%) (p > 0.73). The incidence of transient neurologic dysfunction was also similar (HCA alone, 11% +/- 5%; HCA with RCP, 17% +/- 6%; p > 0.73). Multivariate risk factors for mortality included emergency operation and HCA time (p < 0.02). Risk factors for adverse outcome included emergency operation and atheromatous ascending aorta (p < 0.03). Risk factors for transient neurologic dysfunction included preexisting cerebrovascular disease and rewarming retrograde (femoral) rather than antegrade (through the graft) (p < 0.03). CONCLUSIONS: Supplemental RCP during HCA did not decrease mortality or neurologic complications. Retrograde rewarming through the femoral artery after completion of the distal anastomosis increased transient neurologic dysfunction. Therefore, RCP remains optional, but reperfusion should be antegrade to improve neurologic recovery.

Adult↗
PubMed2002

Can late survival of patients with moderate ischemic mitral regurgitation be impacted by intervention on the valve?

BACKGROUND: Ischemic mitral regurgitation is known to be associated with poor long-term outcome after coronary artery bypass grafting; however, our ability to alter that outcome with intervention on the valve is unclear. The decision to address the valve is most challenging for patients with only moderate mitral regurgitation, particularly with the popularization of off-pump surgery. We therefore reviewed early and late outcomes of patients undergoing revascularization with or without mitral valve surgery. METHODS: Patients with moderate mitral regurgitation undergoing revascularization with and without mitral surgery between January 1991 and September 1996 were identified retrospectively. Operative notes were reviewed and patients with structural valve disease excluded. Perioperative events and late outcomes as determined by telephone contact and search of the social security death index (survival data 97% complete) were compared. RESULTS: One hundred seventy-six patients with moderate mitral regurgitation underwent revascularization alone (n = 142) or with mitral repair or replacement (n = 34). Those undergoing revascularization alone had a higher serum creatinine, somewhat less mitral regurgitation, and lower New York Heart Association functional class preoperatively. Operative mortality was greater with valve surgery (21% vs 9%, p = 0.047). Actuarial survival of both groups at 5 years was similar (52% vs 58%, p = NS); however, when stratified by preoperative functional class, those with more advanced heart failure preoperatively had superior late survival if their mitral valve was intervened upon. CONCLUSIONS: The late survival of patients with ischemic mitral regurgitation undergoing coronary revascularization remains poor; however, intervention on the mitral valve appears to benefit those with symptomatic heart failure.

Adult↗
PubMed2002

Effect of target stenosis and location on radial artery graft patency.

OBJECTIVE: The purpose of this study was to evaluate the effect of target vessel characteristics on radial artery patency when used as a composite T graft. METHODS: Between October 1993 and March 2001, 1022 patients underwent coronary bypass with the internal thoracic artery-radial artery composite T graft. Of these, angiography has been performed on 109 patients at a mean 27.1 months (range, 2-70 months) postoperatively for symptoms of ischemia. By means of Cox proportional hazard models, the relationships between anastomotic patency and target vessel location, proximal stenosis, target diameter, and quality were assessed. RESULTS: A total of 231 radial artery anastomoses were evaluated. The mean stenosis for patent anastomoses was 82% compared with 71% for occluded anastomoses (P <.001). Anastomotic patency for targets with moderate stenosis (< or = 70%) was worse than that for vessels with critical stenosis (> or = 90%; relative risk, 1.7; 95% confidence interval, 1.3-2.2; P <.001). Patency for targets of the right coronary artery was statistically inferior to that for targets of the left anterior descending artery (relative risk, 1.8; 95% confidence interval, 1.2-2.9; P =.01) and bordered on significance versus that for the circumflex artery distribution (relative risk, 1.6; 95% confidence interval, 1.0-2.8; P =.06). When directed toward critically stenosed targets of the left anterior descending or circumflex arteries, radial artery patency was not statistically different that that of the internal thoracic artery (P =.19). CONCLUSION: Radial artery patency is sensitive to both target location and proximal target stenosis. Selective use of the radial artery to targets of the left anterior descending and circumflex distributions remains encouraging. Radial artery grafts to targets of the right coronary artery or those with moderate stenosis appear to be at particularly high risk of failure.

Coronary Artery Bypass↗
PubMed2002

The risk factors for deep and superficial chest surgical-site infections after coronary artery bypass graft surgery are different.

OBJECTIVE: We sought to determine risk factors for deep and superficial chest wound infections after coronary artery bypass graft surgery to develop predictive models. METHODS: We retrospectively analyzed data collected on 1980 consecutive patients undergoing coronary artery bypass surgery at our institution between January 1, 1996, and June 30, 1999, by using the Society of Thoracic Surgery database. Independent risk factors for surgical-site infection were identified with multivariate logistic regression. RESULTS: There were 37 (1.9%) deep chest and 46 (2.3%) superficial chest surgical-site infections. Obese diabetic patients had a 7.7-fold increased risk of deep chest infections after controlling for intra-aortic balloon pump use (odds ratio, 3.1) and postoperative transfusion (odds ratio, 2.3). Independent risk factors for superficial surgical-site infections included obesity (odds ratio, 3.1), diabetes in persons 65 years of age or older (odds ratio, 2.7), and current smoking (odds ratio, 2.5). Use of antiplatelet drugs was associated with a lower risk of superficial infections (odds ratio, 0.4). Predicted operative mortality as a marker of severity of illness was not clearly predictive of deep or superficial surgical-site infection. Mortality in the year after the operation was increased in patients with deep chest infections compared with that seen in uninfected control subjects (8/37 [21.6%] vs 114/1612 [7.1%], P =.004) but not in patients with superficial chest infections (7/47 [15.2%] vs 114/1612 [7.1%], P =.075). CONCLUSIONS: Risk factors for deep and superficial chest surgical-site infections after coronary artery bypass surgery differ, suggesting different mechanisms of pathogenesis. Appropriate risk stratification models specific to these important outcomes must be developed.

Age Factors↗