Biomedical subjects

J E Lowe

Publications and source records attributed to J E Lowe.

At least 37 records · Page 2Linked to original sources

PubMed1999

Perioperative morbidity and mortality after transmyocardial laser revascularization: incidence and risk factors for adverse events.

OBJECTIVES: The purpose of this study was to describe the incidence and spectrum of perioperative cardiac and noncardiac morbidity and mortality after transmyocardial laser revascularization (TMR) and to identify predictors of these adverse clinical events. BACKGROUND: Clinical studies have demonstrated the efficacy of TMR for relieving angina pectoris, although no study to date has specifically addressed the associated perioperative morbidity and mortality. METHODS: Between October 1995 and August 1997, 34 consecutive patients with end-stage coronary artery disease (CAD) underwent isolated TMR. The majority of patients (94%) had class III or IV angina pectoris, and two patients (6%) had unstable symptoms preoperatively. Patient records were reviewed for fatal and nonfatal adverse cardiac and noncardiac events. RESULTS: Perioperative death occurred in two patients (5.9%) due to cardiogenic shock complicating acute myocardial infarction. Perioperative cardiac morbidity occurred in 16 patients (47.1%); noncardiac morbidity was seen in 12 patients (35.3%). Preoperative unstable angina was the only variable predictive of perioperative death (p = 0.005). Cardiac (p = 0.005) and noncardiac (p < 0.001) morbidity rates were significantly higher for the initial 15 patients undergoing the procedure. Other predictors of perioperative complications included lack of postoperative treatment with a furosemide infusion (p < or = 0.04) and preoperative unstable angina (p = 0.05). CONCLUSIONS: Perioperative mortality in patients undergoing isolated TMR is low. Transmyocardial laser revascularization patients are at higher risk for adverse perioperative cardiac and noncardiac events, likely reflecting the lack of immediate benefit from the procedure in the setting of severe CAD. These patients merit vigilant surveillance for adverse events and aggressive medical management in the perioperative period.

Adult↗

PubMed1999

Mortality and need for reoperation in patients with mild-to-moderate asymptomatic aortic valve disease undergoing coronary artery bypass graft alone.

BACKGROUND: Patients presenting for coronary artery bypass graft (CABG) surgery may have concurrent asymptomatic aortic stenosis (AS) or aortic insufficiency (AI). This retrospective study was performed to evaluate outcomes in patients with aortic valve disease undergoing CABG with or without aortic valve replacement (AVR). METHODS: Study groups included 414 patients undergoing combined AVR and CABG (AVR-CABG group) and 62 patients with asymptomatic mild-to-moderate AS, AI, or both undergoing CABG but not AVR (CABG group). End points included 30-day mortality rate, time to cardiac mortality, time to all-cause mortality, and time to aortic valve reoperation. Reoperation refers to surgery for replacement of the native aortic valve in the CABG group or replacement of the prosthetic aortic valve in the AVR-CABG group. Important patient characteristics affecting outcomes were determined by using Cox proportional-hazard analysis. These variables were then included in multivariable analyses by using logistic regression analysis and Cox proportional-hazard modeling to compare outcomes between each patient group. RESULTS: No difference was seen in any of the mortality end points between the CABG group and the AVR-CABG group after controlling for significant differences between the groups. However, the need for reoperation for AVR was significantly higher for the CABG group than the AVR-CABG group. For patients followed for up to 6 years, the estimated need for aortic valve reoperation was 24.3% in the CABG group versus 3% in the AVR-CABG group. CONCLUSION: On the basis of these results, patients with asymptomatic AS or AI should be considered for AVR at the time of CABG.

Aged↗

PubMed1999

Diagnosis, incidence, and clinical significance of early postoperative ischemia after transmyocardial laser revascularization.

BACKGROUND: Clinical improvement after transmyocardial laser revascularization (TMR) is typically delayed, and patients therefore remain at risk for ischemic events after the procedure. The purpose of this study was to define the range of creatine phosphokinase (CPK) and CPK-MB enzyme elevation after TMR and to assess the incidence of early postoperative ischemic events. METHODS: Twenty-one patients undergoing isolated TMR were evaluated for 48 hours after surgery with serial CPK and CPK-MB enzymes and 12-lead electrocardiograms for evidence of myocardial ischemia or injury. Clinically evident postoperative ischemic events including angina pectoris, myocardial infarction (MI), and cardiac death were recorded as well. RESULTS: Eleven patients (52.4%) had ischemic electrocardiographic changes in the first 48 hours after TMR. Ischemia was clinically silent in 7 (63.6%) of these 11 patients. Cardiac death occurred in 1 patient (4.8%) as a result of acute MI. Nonfatal MI occurred in an additional 4 patients (19.0%). Of the 5 patients with MI, 4 had angina pectoris versus no angina in the 16 patients without MI (P =.02). All patients had elevated CPK and CPK-MB levels after TMR: however, peak CPK (P =.02) and CPK-MB (P =. 005) levels were significantly higher for patients suffering postoperative MI compared with those without MI. CONCLUSIONS: Transient ischemia occurs frequently after TMR and is clinically silent in the majority of patients. Patients with postoperative MI are more likely to have symptomatic ischemia as well as significant cardiac enzyme elevation. The combination of 12-lead electrocardiogram and cardiac enzymes appears to have significant merit for the diagnosis of myocardial ischemia and infarction after TMR. These studies should be obtained in all patients undergoing TMR for the first 48 hours after surgery.

Adult↗

PubMed1999

Thoracic complications of peritoneal dialysis.

Approximately 20% of the 100,000 patients in the United States currently undergoing dialysis therapy for end-stage renal disease use the technique of peritoneal dialysis. We present a patient on peritoneal dialysis who developed a large posterior mediastinal mass, which on surgical exploration was found to be a paraesophageal hernia sac filled with omentum and dialysis fluid. We use this case as an introduction to review the thoracic complications of peritoneal dialysis.

Adult↗

PubMed1999

Improved perfusion and contractile reserve after transmyocardial laser revascularization in a model of hibernating myocardium.

BACKGROUND: Transmyocardial laser revascularization (TMR) has been demonstrated effective for relieving angina, although prior studies have yielded inconsistent results regarding postoperative myocardial perfusion and function. This study evaluated long-term changes in myocardial perfusion and contractile reserve after TMR in a model of hibernating myocardium. METHODS: Miniswine had subtotal left circumflex coronary artery occlusion to reduce resting blood flow to 10% of baseline. After 2 weeks in the low-flow state, positron emission tomography and dobutamine stress echocardiography were performed to document ischemic, viable (hibernating) myocardium in the left circumflex distribution. Animals then had sham redo thoracotomy (n = 4) or TMR (n = 6). Six months later the positron emission tomography and dobutamine stress echocardiography studies were repeated. RESULTS: Myocardial blood flow in the left circumflex distribution as measured by positron emission tomography was significantly reduced in all animals after 2 weeks in the low-flow state. In animals that had TMR, there was significant improvement in myocardial blood flow to the lased regions 6 months postoperatively. No significant change in myocardial blood flow was seen in sham animals at 6 months. Dobutamine stress echocardiography after 2 weeks of low-flow demonstrated severe hypocontractility at rest in the left circumflex region of all animals, with a biphasic response to dobutamine consistent with hibernating myocardium. In animals that had TMR, there was a trend toward improved resting function and significantly improved regional stress function in the lased segments 6 months postoperatively, consistent with a reduction in ischemia. Global left ventricular wall motion at peak stress improved significantly as well. There was no change in wall motion 6 months postoperatively in sham-operated animals. CONCLUSIONS: This study found improvements in myocardial perfusion and regional and global contractile reserve 6 months after TMR in a porcine model of hibernating myocardium. This improved perfusion and function likely accounts for the clinical benefits of the procedure.

Animals↗

PubMed1999

Transmyocardial laser revascularization in the patient with unmanageable unstable angina.

BACKGROUND: Transmyocardial laser revascularization (TMR) provides relief for patients with chronic angina, nonamenable to direct coronary revascularization. Unmanageable, unstable angina (UUA) defines a subset of patients with refractory angina who are at high risk for myocardial infarction and death. Patients were classified in the UUA group when they had been admitted to the critical care unit with unstable angina for 7 days with three failed attempts at weaning them off intravenous antianginal medications. METHODS: Seventy-six treated patients were analyzed to determine if TMR is a viable option for patients with unmanageable unstable angina. These patients were compared with 91 routine protocol patients (protocol group [PG]) undergoing TMR for chronic angina not amenable to standard revascularization. The procedure was performed through a left thoracotomy without cardiopulmonary bypass. These patients were followed for 12 months after the TMR procedure. Both unmanageable and chronic angina patients had a high incidence of at least one prior surgical revascularization (87% and 91%, respectively). RESULTS: Perioperative mortality (< or = 30 days post-TMR) was higher in the UUAG versus PG (16% vs 3%, p = 0.005). Late mortality, up to 1 year of follow-up, was similar (13% vs 11%, UUAG vs PG; p = 0.83). A majority of the adverse events in the UUAG occurred within the first 3 months post-TMR, and patients surviving this interval did well, with reduced angina of at least two classes occurring in 69%, 82%, and 82% of patients at 3, 6, and 12 months, respectively. The percent improvement in angina class from baseline was statistically significant at 3, 6, and 12 months. A comparable improvement in angina was found in the protocol group of patients. CONCLUSIONS: TMR carried a significantly higher risk in unmanageable, unstable angina than in patients with chronic angina. In the later follow-up intervals, however, both groups demonstrated similar and persistent improvement in their angina up to 12 months after the procedure. TMR may be considered in the therapy of patients with unmanageable, unstable angina who otherwise have no recourse to effective therapy in the control of their disabling angina.

Adult↗

PubMed1999

Endoscopic versus open saphenous vein harvest: the effect on postoperative outcomes.

BACKGROUND: Endoscopic vein harvest (EVH) has been promoted as a possible solution to the wound complications, incisional pain, and prolonged convalesce associated with open vein harvesting (OVH). The purpose of this study was to objectively compare the two techniques. METHODS: One hundred patients were prospectively randomized to EVH or OVH. Primary outcomes were wound complications, pain (Medical Outcomes Study Pain Survey), and general health (SF-12). Secondary outcomes were operative times and patient preferences. Patients were assessed at hospital discharge, 3, and 6 weeks postdischarge. RESULTS: No significant differences were detected in the primary outcomes: leg infection (p = 0.75), incisional pain (p = 0.74), physical health (p = 0.84), mental health (p = 0.47), and postoperative length of stay (p = 0.74). However, patient preference for EVH was highly significant (p < 0.01). CONCLUSIONS: EVH does not demonstrate significant differences compared with OVH. This, coupled with higher operating room costs, should limit its use until clinical benefit is shown. However, strong patient preference and demand for EVH overshadow equivocal clinical outcomes.

Aged↗

PubMed1999

Transmyocardial laser revascularization limits in vivo adenoviral-mediated gene transfer in porcine myocardium.

OBJECTIVE: Transmyocardial laser revascularization (TMR) is emerging as a potential treatment option for patients with end-stage CAD, and adjuvant gene therapy may be helpful in further improving the results of the procedure. However, the effects of TMR on gene transfer are unknown. METHODS: Swine underwent left thoracotomy. TMR was performed to create five channels at 2-cm intervals in the anterolateral free wall of the left ventricle (LV) followed by injection of 1 x 10(9) plaque-forming units (pfu) of a replication-deficient adenovirus vector carrying the reporter gene beta-galactosidase (Ad.Pac beta-gal). An additional five direct injections of 1 x 10(9) pfu Ad.Pac beta-gal were made at 2-cm intervals in the posterolateral LV of each heart. Control animals underwent TMR alone/vehicle alone (n = 3) or empty virus alone/no treatment (n = 3) of the anterolateral/posterolateral LV, respectively. RESULTS: ELISA revealed significantly greater transgene expression in the direct Ad.Pac beta-gal injection versus TMR plus Ad.Pac beta-gal inject regions at both 3 (n = 6) (273.0 +/- 58.5 vs. 133.4 + 28.1 pg beta-gal/g protein, P = 0.02) and 7 days (n = 6) (180.0 + 59.9 vs. 56.7 + 18.1 pg beta-gal/g protein, P = 0.02) postoperatively. At 14 days postoperatively (n = 2), no transgene expression was detected in either region. No transgene expression was detected in any of the control regions at 3 days postoperatively. CD-18 staining revealed significantly greater inflammation in the TMR plus Ad.Pac beta-gal and TMR alone regions as compared to Ad.Pac beta-gal or vehicle (P < 0.001). CONCLUSIONS: Adenoviral-mediated gene transfer in conjunction with TMR is possible, although TMR appears to limit the degree of transgene expression attained as compared to direct intramyocardial injection alone, likely due to the greater immune response observed with the former. These findings may have important implications for therapeutic strategies aimed at combining TMR with gene therapy for CAD.

Adenoviridae↗

PubMed1999

Long-term outcome after biologic versus mechanical aortic valve replacement in 841 patients.

OBJECTIVE: The purpose of this study was to optimize selection criteria of biologic versus mechanical valve prostheses for aortic valve replacement. METHODS: Retrospective analysis was performed for 841 patients undergoing isolated, first-time aortic valve replacement with Carpentier-Edwards (n = 429) or St Jude Medical (n = 412) prostheses. RESULTS: Patients with Carpentier-Edwards and St Jude Medical valves had similar characteristics. Ten-year survival was similar in each group (Carpentier-Edwards 54% 3% versus St Jude Medical 50% 6%; P =.4). Independent predictors of worse survival were older age, renal or lung disease, ejection fraction less than 40%, diabetes, and coronary disease. Carpentier-Edwards versus St Jude Medical prostheses did not affect survival (P =.4). Independent predictors of aortic valve reoperation were younger age and Carpentier-Edwards prosthesis. The linearized rates of thromboembolism were similar, but the linearized rate of hemorrhage was lower with Carpentier-Edwards prostheses (P <.01). Perivalvular leak within 6 months of operation was more likely with St Jude Medical than with Carpentier-Edwards prostheses (P =.02). Estimated 10-year survival free from valve-related morbidity was better for the St Jude Medical valve in patients aged less than 65 years and was better for the Carpentier-Edwards valve in patients aged more than 65 years. Patients with renal disease, lung disease (in patients more than age 60 years), ejection fraction less than 40%, or coronary disease had a life expectancy of less than 10 years. CONCLUSIONS: For first-time, isolated aortic valve replacement, mechanical prostheses should be considered in patients under age 65 years with a life expectancy of at least 10 years. Bioprostheses should be considered in patients over age 65 years or with lung disease (in patients over age 60 years), renal disease, coronary disease, ejection fraction less than 40%, or a life expectancy less than 10 years.

Adolescent↗

PubMed1999

Depletion of total antioxidant capacity in type 2 diabetes.

The purpose of the study was to examine the relationship between antioxidant depletion, glycemic control, and development of chronic complications in a controlled population of type 2 diabetic patients. Fifty age-matched type 2 diabetic patients receiving sulfonylureas but not insulin treatment were screened and assigned to two groups based on the presence or absence of proteinuria. A third group of normal subjects without diabetes were also enrolled in the study. All subjects in the three groups were Egyptians who were matched for body weight, and the two diabetic groups were also age-matched. Plasma glucose and fructosamine levels were higher in the two groups of diabetic patients versus the control group, but lipid peroxide levels were higher only in the patients with proteinuria. Compared with the control group, the total antioxidant capacity was depleted in the two diabetic groups, but the depletion was more severe in patients with proteinuria. Thus, the mean Trolox equivalent antioxidant capacity (TEAC) of the control group was 2.7+/-0.45, versus 1.7+/-0.5 (P < .001) in the patients without proteinuria. Furthermore, the TEAC measured in patients with proteinuria, who also had more diabetic complications, was lower (1.4+/-0.5, P < .001) than the TEAC in patients without urinary protein. In conclusion, a depletion of the total antioxidant capacity is associated with a higher incidence of diabetic complications.

Adult↗

PubMed1999

Adenosine myocardial protection: preliminary results of a phase II clinical trial.

OBJECTIVE: To evaluate the safety, tolerance, and efficacy of adenosine in patients undergoing coronary artery bypass surgery. SUMMARY BACKGROUND DATA: Inadequate myocardial protection in patients undergoing coronary artery bypass surgery contributes to overall hospital morbidity and mortality. For this reason, new pharmacologic agents are under investigation to protect the regionally and globally ischemic heart. METHODS: In a double-blind, placebo-controlled trial, 253 patients were randomized to one of three cohorts. The treatment arms consisted of the intraoperative administration of cold blood cardioplegia, blood cardioplegia containing 500 microM adenosine, and blood cardioplegia containing 2 mM adenosine. Patients receiving adenosine cardioplegia were also given an infusion of adenosine (200 microg/kg/min) 10 minutes before and 15 minutes after removal of the aortic crossclamp. Invasive and noninvasive measurements of ventricular performance were obtained before, during, and after surgery. RESULTS: The high-dose adenosine cohort was associated with a trend toward a decrease in high-dose dopamine support and a lower incidence of myocardial infarction. A composite outcome analysis demonstrated that patients who received high-dose adenosine were less likely to experience one of five adverse events: high-dose dopamine use, epinephrine use, insertion of intraaortic balloon pump, myocardial infarction, or death. The operative mortality rate for all patients studied was 3.6% (9/253). CONCLUSIONS: Adenosine treatment is safe and well tolerated and may be associated with fewer postoperative complications.

Adenosine↗

PubMed1999

Stimulation of long-chain fatty acid uptake by dipyridamole in isolated myocytes.

This study was designed to investigate the effects of the cardiovascular drug dipyridamole on fatty acid metabolism in isolated cardiac myocytes. Effects of dipyridamole on the oxidation of long-chain (palmitate) fatty acid, medium-chain (octanoate) fatty acid, and the carbohydrate intermediate (pyruvate) were determined by using isolated cardiac myocytes from both normal and diabetic rats. Dipyridamole increased palmitate oxidation in a concentration-dependent manner in both normal and diabetic myocytes. Maximal stimulation of palmitate oxidation (175% of control) was observed with 100 microM dipyridamole. In contrast, oxidation of octanoate and pyruvate was not affected. The stimulation of palmitate oxidation by dipyridamole persisted despite its removal from the incubation medium. In contrast to the effect in myocytes, palmitate oxidation was not affected by dipyridamole in isolated rat heart mitochondria. Palmitate uptake was increased by 2.5- and 1.6-fold when palmitate concentration was adjusted to 0.05 and 0.2 mM, respectively. Dipyridamole did not affect lipolysis in isolated myocytes. When dipyridamole (100 microM) and L-carnitine (5 mM) were added together to the incubation medium, palmitate oxidation was further increased to 223% of the control. The nucleoside transport inhibitor nitrobenzylthioinosine (NBMPR) failed to increase palmitate oxidation in isolated myocytes. Although palmitate oxidation in diabetic cells is much higher than that in normal myocytes, dipyridamole increased palmitate oxidation by 243% in diabetic myocytes over its baseline oxidation rate in normal cells. These results suggest that increased palmitate oxidation in isolated cardiac myocytes after dipyridamole administration occurs independent of effects on either the phosphodiesterase enzyme or nucleoside transport protein, but it may result from increased palmitate transport across the plasma membrane.

Animals↗

PubMed1999

Transmyocardial laser revascularization: experimental and clinical results.

BACKGROUND: Transmyocardial laser revascularization (TMR) is an emerging therapy for the treatment of coronary artery disease not amenable to percutaneous transluminal coronary angioplasty (PTCA) or coronary artery bypass surgery (CABG). OBJECTIVE: To summarize the experimental and clinical experience to date with TMR. Specifically, the history of the technique, preclinical and clinical data, patient selection and perioperative management, as well as future applications of TMR are discussed. DATA SOURCES: All English language articles pertaining to TMR published through March 1999. MEDLINE was searched with the key words 'myocardial revascularization', 'lasers' and 'laser surgery', as well as the text terms 'transmyocardial laser revascularization', 'TMR' and 'TMLR'. Reference lists of articles obtained from MEDLINE were studied for additional references not discovered in computer searches. Pertinent abstracts published within the past two years were reviewed as well. STUDY SELECTION: Studies that produced original experimental or clinical data were selected. DATA SYNTHESIS: Experimental studies demonstrate that TMR channels become occluded in the early postoperative period. However, experimental data indicate that laser injury appears to promote neovascularization with secondary improvements in perfusion in treated regions. Human clinical studies confirm the efficacy of the procedure, with significant improvements in anginal class up to at least one year postoperatively, although documented improvements in myocardial perfusion have been less consistent. Perioperative morbidity and mortality appear to be increased in patients with unstable angina or reduced left ventricular function. CONCLUSIONS: With careful patient selection and peri- operative management, TMR is a safe and effective therapy for severe angina pectoris secondary to end-stage coronary artery disease. Additional studies are required to define the role of TMR in combination with PTCA, CABG and angiogenic growth factors, as well as the safety and efficacy of catheter-based TMR.

Angina Pectoris↗

PubMed1998

Comparison of open mitral commissurotomy with mitral valve replacement with or without chordal preservation in patients with mitral stenosis.

BACKGROUND: Percutaneous balloon mitral valvuloplasty and durable mitral prostheses have made the role of open mitral commissurotomy (OMC) uncertain. METHODS AND RESULTS: Results from the use of St Jude mitral valve replacement (SJMVR) were compared with those of the use of OMC in 312 consecutive patients with mitral stenosis between 1983 and the present. OMC and SJMVR patients were well matched for age, sex, and comorbidity except that SJMVR patients had more severe stenosis and were more likely to undergo concurrent aortic valve replacement. Compared with OMC, SJMVR without chordal preservation involved a longer pump time (158 +/- 81 versus 87 +/- 41 min, P < 0.05), more frequent in-hospital complications or death (57 of 219 [26%] versus 4 of 52 [8%], P < 0.01), and longer hospital stay (13 +/- 11 versus 10 +/- 6 days, P = 0.001). Preservation of chordae to at least 1 mitral valve leaflet decreased early morbidity and mortality rates of SJMVR to values comparable to those of OMC (3 of 41 [7%]). Survival was greater at 10 years for OMC versus SJMVR (86 +/- 5% versus 67 +/- 4%, P = 0.03). Ten-year freedom from cardiac events was not different between groups (49 +/- 9% for OMC versus 55 +/- 4% for SJMVR, P = 0.7). Freedom from subsequent mitral procedures at 10 years was better for SJMVR (96 +/- 2% versus 58 +/- 8%, P < 0.001). CONCLUSIONS: In the modern era, SJMVR offers significantly greater durability than does OMC. Chordal preservation at the time of SJMVR may reduce perioperative complications to levels comparable to those of OMC.

Adult↗

PubMed1998

Factors affecting the DNA damaging activity of superoxide and nitric oxide.

Nitric oxide and superoxide are formed endogenously and can react with each other and with other molecules to form a range of secondary and tertiary products. Some of these (e.g., peroxynitrite) are potent DNA-damaging agents and others (e.g., S-nitrosoglutathione) can act as reservoirs of the reactive species. Although the chemistry of these processes is now becoming understood, the question of which products are significant in vivo is not necessarily clear. To investigate these processes we have developed a cell-free version of the Comet assay, where the DNA from isolated nuclei is treated in agar on a microscope slide, following lysis. This offers an exceptionally sensitive assay for strand breakage in free DNA. Despite being present as a scavenger in the cell at millimolar levels, glutathione can act as a DNA-damaging pro-oxidant. Under appropriate conditions, glutathione-mediated damage is suppressed by superoxide dismutase and we suggest that superoxide may be a direct damaging agent, whose activity can be masked because of the involvement of superoxide in indirect mediation of damage or because of concomitant presence of hydroxyl radical.

Animals↗

PubMed1998

Use of the Comet assay to investigate the role of superoxide in glutathione-induced DNA damage.

Although glutathione is an important scavenging molecule within the cell, it can also act as a pro-oxidant and at biological concentrations (1 mM) can induce DNA damage. We have used a sensitive cell-free Comet assay for DNA strand breakage to investigate this damage and to try to determine the active species involved. We show a substantial protection against glutathione-mediated DNA damage by superoxide dismutase (200 U/ml) and complete protection by combined superoxide dismutase and catalase. Damage is also prevented by EDTA but only at 100 mM and is not prevented by the chelating agent diethylenetriamine-pentaacetic acid (100 microM). Although superoxide is known to potentiate DNA damage by other reactive species, none of these indirect mechanisms seem to account for our results and it is possible that superoxide may damage DNA directly. Under the same experimental conditions, S-nitrosoglutathione requires ultraviolet A photolysis to cause DNA strand breakage and superoxide dismutase increases the level of this damage. When intact human lymphocytes are incubated with glutathione (1 mM) in phosphate buffer, DNA damage is also observed, but in this case it is completely preventable by catalase, with no protective effect of superoxide dismutase. Since cellular scavenging systems are not completely protective against reactive species formed from autooxidation of extracellular glutathione and since glutathione and oxygen are ubiquitously present within cells, our results imply that cells may have a mechanism of preventing autooxidation, rather than simply relying on scavenging the reactive species formula.

Catalase↗

PubMed1998

Combined TMR and mitral valve replacement via left thoracotomy.

Transmyocardial laser revascularization is an emerging technique for treatment of patients with coronary artery disease not amenable to standard revascularization by either percutaneous transluminal coronary angioplasty or coronary artery bypass grafting. Transmyocardial laser revascularization is typically performed as an isolated procedure on the beating heart, although it has been performed as an adjunct to conventional coronary artery bypass grafting in nongraftable territories. We report the use of transmyocardial laser revascularization in combination with mitral valve replacement via a left lateral thoracotomy for treatment of ischemic mitral regurgitation.

Angina, Unstable↗

PubMed1998

Neovascularization after transmyocardial laser revascularization in a model of chronic ischemia.

BACKGROUND: The mechanism of clinical improvement after transmyocardial laser revascularization (TMR) is unknown. One hypothesis holds that TMR causes increased myocardial perfusion through neovascularization. This study sought to determine whether angiogenesis occurs after TMR in a porcine model of chronic myocardial ischemia. METHODS: Six miniature pigs underwent subtotal left circumflex coronary artery occlusion to reduce resting blood flow to 10% of baseline. After 2 weeks in the low-flow state, dobutamine stress echocardiography and positron emission tomography were performed to document ischemic, viable myocardium. The animals then underwent TMR and were sacrificed 6 months later for histologic and immunohistochemical analysis. RESULTS: Histologic analysis of the lased left circumflex region demonstrated many hypocellular areas filled with connective tissue representing remnant TMR channels. Histochemical staining demonstrated a highly disorganized pattern of neovascularization consistent with angiogenesis located predominantly at the periphery of the channels. Immunohistochemical analysis confirmed the presence of endothelial cells within neovessels. Vascular density analysis revealed a mean of 29.2+/-3.6 neovessels per high-power field in lased ischemic myocardium versus 4.0+/-0.3 (p<0.001) in nonlased ischemic myocardium. CONCLUSIONS: This study provides evidence that neovascularization is present long term in regions of ischemic, viable myocardium after TMR. Angiogenesis may represent the mechanism of clinical improvement after TMR.

Animals↗