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Biomedical subjects

A Blitz

Publications and source records attributed to A Blitz.

18 recordsLinked to original sources
PubMed1998

Use of leukocyte depletion to decrease injury after lung preservation and rewarming ischemia: an experimental model.

BACKGROUND: Hypothermia is critical for proper lung preservation. Ideally, the lungs should be maintained at the optimal preservation temperature during the entire ischemic interval. Lung rewarming during implantation is commonly observed. This study was undertaken to investigate the severity of rewarming ischemia on preservation injury and the possibility of minimizing this by use of leukocyte depletion during initial reperfusion. METHODS: Four experimental groups were tested as follows: neonatal piglet heart-lung blocks were either (1) placed on an isolated, blood-perfused, working heart-lung circuit without intervening ischemia (control, n = 6), (2) reperfused on the circuit with whole blood (WB, n = 6) after 13 hours of preservation, (3) reperfused with WB after 12 hours of preservation and 1 hour of rewarming (RWB, n = 5), or (4) reperfused with leukocyte-depleted blood for an initial 10 minutes followed by WB, after 12 hours of preservation and 1 hour of rewarming (n = 6). All groups were studied for 4 hours. RESULTS: The partial pressure of arterial oxygen and lung compliance were significantly lower in the RWB group than in controls (113.8+/-33.1 vs 417.3+/-6.2 mm Hg, p < 0.01; and 0.8+/-0.2 vs 2.9+/-0.4 ml/cm H2O, p < 0.05, respectively). Pulmonary vascular resistance and lung wet/dry weight ratios were significantly higher in the RWB group than in controls (15884.1+/-11354.8 vs 6108.3+/-1309.9 dyne x sec x cm[-5], p < 0.05; and 7.13+/-0.24 vs 5.82+/-0.35, p < 0.05, respectively). The WB and leukocyte-depleted groups did not differ significantly from controls for any measured parameter. CONCLUSIONS: This model confirms that rewarming ischemia during lung implantation exacerbates reperfusion injury. Leukocyte-depleted reperfusion as tested for a short period of time (10 minutes) ameliorates this injury and therefore should be considered for clinical lung transplantation.

Animals↗
PubMed1997

The Fontan procedure in adults.

BACKGROUND: A retrospective clinical study was performed to document the course of adult patients undergoing the Fontan procedure. METHODS: Between 1982 and 1994, 21 adults aged 18 to 40 years (mean age, 27 +/- 7 years) underwent a Fontan procedure. Anatomic diagnosis was tricuspid atresia in 9, double-inlet left ventricle in 4, and various single ventricles in 8. Four underwent a right atria-right ventricle connection, 13 had a right atria-pulmonary artery connection, and 4 had a lateral-tunnel Fontan. Three of these 4 had a snare-adjustable atrial septal defect. Preoperative risk factors assessed were left ventricular end-diastolic pressure greater than 10 mm Hg, ejection fraction lower than 0.45, mean pulmonary artery pressure higher than 15 mm Hg, transpulmonary gradient greater than 10 mm Hg, pulmonary artery abnormalities, and atrioventricular valve regurgitation. Mean preoperative risk score was 1.6 /-1.1. Mean New York Heart Association class was 2.6 +/- 0.5. RESULTS: The operative mortality rate was 5% (1/21). Six patients (30%) had a major complication, four being prolonged effusions. One patient was lost to follow-up; the remaining 20 have been followed for a mean of 7.4 +/- 3.8 years. At follow-up, mean New York Heart Association class was 1.7 +/- 0.5. There has been one late death (5%) at 9 2/3 years, which was probably due to ventricular arrhythmia. Three patients (16%) have required and survived reoperation. During follow-up, 7 patients (37%) have had development of atrial arrhythmias requiring medication, and 2 have been treated for ventricular arrhythmias. CONCLUSIONS: These results indicate that properly selected adults can undergo the Fontan procedure with low morbidity and mortality. However, late-developing arrhythmias, need for reoperation, and decreasing ventricular function are serious problems that mandate careful follow-up.

Adult↗
PubMed1997

The alternate recipient list for heart transplantation: does it work?

BACKGROUND: One quarter of patients awaiting heart transplantation die while on the waiting list. This is largely due to the shortage of donor organs. The alternate recipient list was created to establish a means by which patients who would otherwise be turned down for heart transplantation solely because of age over 65 or a need for a third heart transplantation can receive organs considered marginal that may otherwise be wasted. The hope is that these patients may achieve improved survival with these substandard hearts than they would achieve with medical therapy alone. METHODS: Twenty-two patients ages 47 to 71 years (mean 66.7 years) were listed on the alternate recipient list at the University of California at Los Angeles Medical Center from 1991 to 1996. Seventeen patients underwent heart transplantation from the alternate waiting list. The outcome of this group was compared with the outcome of a contemporaneous group of 266 patients ages 18 to 66 years (mean age 52.1 years) from the standard heart transplantation waiting list. RESULTS: The early mortality rate for the patients in the alternate group was 11.8% (2/ 17). Actuarial survival from time of orthotopic heart transplantation at 6 months and 1 year was the same 74.5% at a mean follow-up was 13.4 months. In comparison, the early mortality rate for the patients on the standard list was 5.6% (15/266), and actuarial survival at 6 months and 1 year was 86.8% and 83.1%, respectively (mean follow-up was 30 months). There was no significant difference in early mortality rate or actuarial survival between the two groups. CONCLUSION: The alternate recipient list for heart transplantation is a valid and ethical option for patients who would otherwise be denied heart transplantation. It provides these patients with similar early and medium-term outcomes in comparison to patients on the standard list, and organs that may otherwise be wasted are used.

Adolescent↗
PubMed1996

L-arginine administration during reperfusion improves pulmonary function.

BACKGROUND: Nitric oxide is crucial to the maintenance of vascular homeostasis. Because nitric oxide levels decline upon lung reperfusion, infusion of L-arginine, a nitric oxide precursor, during reperfusion might prove effective at ameliorating reperfusion injury. METHODS: Neonatal piglet heart-lung blocks were preserved with Euro-Collins solution for 12 hours, rewarmed at room temperature for 1 hour, and reperfused for 10 minutes with either whole blood (n = 5), whole blood containing L-arginine (10 mmol/L; n = 6), or leukocyte-depleted blood (n = 6) on an isolated, blood-perfused, working heart-lung circuit. After the initial 10 minutes, all blocks received whole blood for 4 hours. Control blocks were continuously perfused on the circuit without intervening ischemia (n = 6). RESULTS: The partial pressure of oxygen in the whole blood group (113.8 +/- 33.1 mm Hg) was significantly less than in controls (417.3 +/- 6.2 mm Hg; p < 0.01). Lung compliance was significantly less in the whole blood group (0.8 +/- 0.2 mL/cm H2O) than in controls (2.9 +/- 0.4 mL/cm H2O; p < 0.01). The L-arginine and leukocyte-depleted blood groups showed no significant difference from controls. CONCLUSIONS: L-Arginine infusion during reperfusion improves pulmonary function, making it a simple alternative to leukocyte depletion.

Animals↗
PubMed1996

Preservation of endothelium-dependent vasodilation with low-potassium University of Wisconsin solution.

University of Wisconsin solution has provided excellent myocardial preservation. However, the high potassium content of the currently available University of Wisconsin solution has been implicated in coronary artery endothelial damage. We placed 16 neonatal (age 1 to 3 days) Duroc piglet hearts on an isolated nonworking perfusion circuit. Endothelium-dependent and endothelium-independent vasodilation were tested by measuring coronary blood flow after intracoronary infusion of bradykinin (10(-6) mol/L) and nitroprusside (10(-6) mol/L), respectively. In addition, nitric oxide levels were measured after bradykinin infusion. The hearts were then arrested blindly with either a modified University of Wisconsin solution (group 1; n = 8, K+ = 25 mEq/L) or standard University of Wisconsin solution (group 2; n = 8, K+ = 129 mEq/L) by infusion of cardioplegic solution every 20 minutes for a total of 2 hours. After bradykinin infusion, the mean coronary blood flow increased by 237.1% +/- 14.0% of baseline valves before arrest and by 232.8% +/- 16.0% after arrest in group 1 (p = not significant). As in the first group, the mean coronary blood flow in group 2 increased by 231.1% +/- 13.7% before arrest; however, the increase in mean coronary blood flow after arrest was significantly attenuated (163.3% +/- 12.8%, p < 0.01). The loss of endothelium-dependent coronary blood flow response in group 2 correlated with a decreased capacity to release nitric oxide after arrest (prearrest 8.25 +/- 2.30 nmol/min per gram versus postarrest -2.46 +/- 2.29 nmol/min per gram, p < 0.01). Endothelium-independent vasodilatory response revealed no significant difference between groups before and after arrest. These results suggest that the low-potassium University of Wisconsin solution provides superior protection of the endothelium by preserving the endothelium-dependent vasodilatory response to nitric oxide release.

Adenosine↗
PubMed1996

Cardiac gene transfer by intracoronary infusion of adenovirus vector-mediated reporter gene in the transplanted mouse heart.

This study introduces a model for intracoronary gene transfer in murine cardiac isografts using adenovirus vectors. This approach may offer an opportunity to modulate alloreactivity after cardiac transplantation. Donor hearts were infected via the coronary arteries with a volume of 10(9) plaque-forming units per milliliter of a recombinant adenovirus containing the beta-galactosidase-encoding gene (Ad.CMVLacZ). In a control group, 200 microliters of normal saline solution was infused. The grafts were stored in 4 degrees C cold saline solution for 15 minutes, then transplanted heterotopically into syngeneic hosts (B10.BR). The grafts were harvested at 3, 7, 15, or 30 days (n = 5 for each group) after transplantation, and beta-galactosidase activity was assessed by histochemical staining (X-gal). All grafts were functioning when harvested. X-gal staining pattern was nonuniform with positive staining appearing in epicardial, myocardial, and endocardial cells, as well as in the vessel walls. The cells permissive to infection consisted predominantly of myocardial cells. The mean total numbers of beta-gal-positive staining cells per slice were 68.7 +/- 27.3 in the 3-day group, 330.4 +/- 53.8 in the 7-day group, 151.3 +/- 48.0 in the 15-day group, and 39.9 +/- 10.8 in the 30-day group, thus peaking in the 7-day group (p < 0.05). Control isografts (n = 5), retrieved at day 30, revealed no staining activity. In conclusion, our model demonstrates that intracoronary gene transfer to the transplanted murine cardiac grafts is feasible at the time of harvest. Adenovirus-mediated gene transfer produces widespread gene expression which, though perhaps transient, does not adversely affect myocardial structure or function. This technology may allow modification of graft immunogenicity in the future through the production of therapeutic proteins sufficient to modulate local immune responses.

Adenoviridae↗
PubMed1996

The role of coronary revascularization in the management of heart failure: identification of candidates and review of results.

As a result of the increasing size of waiting lists and lengthening of waiting times for heart transplantation, coronary revascularization has emerged as an important therapeutic option in the management of patients with ischemic cardiomyopathy. A critical challenge is the identification of candidates with regions of hibernating myocardium, because these patients stand to benefit the most from revascularization. In this review we summarize the recent literature examining the techniques used to identify myocardial hibernation. In addition, we evaluate the results of revascularization in this challenging group of patients.

Adult↗
PubMed1996

The use of positron emission tomography imaging in the management of patients with ischemic cardiomyopathy.

Rational management of patients with CAD and poor left ventricular function relies on proper identification of the subgroup at high risk and those who have the highest potential of benefiting from a particular type of treatment. It is now well recognized that patients with CAD and left ventricular dysfunction have a high but variable mortality rate while receiving medical therapy. Many of these patients who have intractable heart failure are considered candidates for cardiac transplantation. Despite favorable survival after cardiac transplantation, this procedure cannot be performed in 90% of the heart failure patients who are potentially eligible because of the shortage of donor hearts. Cardiac transplantation is also an expensive procedure. Perfusion-FDG metabolism PET imaging has become the gold-standard noninvasive imaging method to identify the presence and extent of hibernating myocardium. Positron emission tomography accurately predicts recovery of regional and global left ventricular dysfunction after revascularization. In patients with poor left ventricular function, the PET pattern of perfusion metabolism mismatch is also predictive of improvement in heart failure symptoms and survival benefit after myocardial revascularization. These data suggest that a rational approach may be developed for cost-effective management of patients with CAD and poor left ventricular function.

Cell Survival↗
PubMed1996

Outcomes of patients undergoing transplantation with older donor hearts.

BACKGROUND: The limited number of donor hearts relative to the number of waiting recipients is the major determinate of a growing inequity. Although a number of potential options are being vigorously pursued, the most effective immediate solution is to expand acceptance criteria for donor age and medical condition. This report is a review of our early and late results with the use of older donors, including simultaneously "bypassed" donor hearts. METHODS: Between April 1987 and September 1994, 52 patients received older donor hearts (older than 45 years) with a mean donor age of 51 years. Ten patients in this group received hearts simultaneously bypassed with from 1 to 4 grafts per patient. Donor and recipient age, diagnosis, and HLA match were compared between the older donor group and a contemporaneous younger (younger than 45) donor group (N = 324). Also compared was actuarial survival at up to 5 years of follow-up in addition to graft function, bypass graft patency, infection and rejection incidence at 1 year, and the prevalence of transplant-associated coronary artery disease in the two groups. Echocardiography, coronary angiography, and intravascular coronary ultrasonography were used for this assessment. RESULTS: One-year actuarial survival was 84% for the older donor group, which included 19 status 1 patients (survival 76%) and 23 status II patients (survival 90%). In the bypassed donor subgroup there was a 60% 1-year actuarial survival with 5 status 1 patients (survival 80%) and 5 status II patients (survival 40%). At 1 year, left ventricular function and the incidence of infection and rejection were equal between these two donor groups. Five-year actuarial survivals were the same between the overall older and younger donor groups. Finally, the development of transplant-associated coronary disease was similar in both groups up to 5 years after transplantation. CONCLUSIONS: This initial review of heart transplantation with older donor hearts, including bypassed hearts, demonstrates similar early and late survival outcomes as compared with those of a contemporaneous younger donor group. Significantly, there appears to be no difference in the development of transplant-associated coronary artery disease during the follow-up period. The older donor represents a potential immediate increase in the number of suitable hearts for transplantation. Bypassed donor hearts represent a small but potentially significant subgroup that may be safely and effectively used when appropriately matched to the recipient by age and medical condition. Greater experience, particularly with this bypassed group, will help determine optimal donor-to-recipient matching for the future.

Adult↗
PubMed1995

The University of California at Los Angeles experience in heart transplantation.

In the last decade, the number of patients undergoing heart transplantation has steadily increased as a result of expanding indications for cardiac transplantation. The limitation on the number of transplants performed has been the number of donor organs available. At UCLA, 511 heart transplant procedures were performed from 1984-1994. The mean number of rejection episodes and infections per patient in the first year after transplant was 1.1+/-1.3 and 1.0+/-1.2, respectively. Actuarial one-, 3-, and 5-year survival rates were 84%, 77% and 73%, respectively. Survival of patients age 60 years and over (n=105) was comparable to that of patients under age 60. Despite transplanting more critically ill patients (Status 1) and having longer cold ischemic times, outcomes have been improving. We have been pursuing corticosteroid-free immunosuppression, which no doubt has led to the decrease in infection complications. Furthermore, our work with pravastatin early after transplantation has led to a decrease in clinically severe rejection episodes which has translated into improved survival. Pravastatin also appeared to decrease the development of transplant coronary artery disease and appeared to have an adjunct immunosuppressive effect in our heart transplant patients on CsA-based immunosuppression. Future studies will include the use of mycophenolate mofetil which has properties against B-lymphocytes in addition to T-lymphocytes to block both humoral and cellular rejection. Our program continues to seek better ways to improve survival and the quality of life of our patient population.

Academic Medical Centers↗
PubMed1994

Wound healing after harvesting of the internal thoracic and the superior and inferior epigastric arteries.

Wound healing of sternal incisions and midline or paramedian abdominal incisions was studied at 2 weeks postoperatively in three groups of dogs. Group 1, 10 dogs, had harvesting of bilateral internal thoracic arteries, superior epigastric arteries, and inferior epigastric arteries. Group 2, 5 dogs, had removal of the same arteries, but the superior and inferior epigastric arteries were harvested through paramedian rather than midline incisions. Group 3, 5 dogs, served as control and had median sternotomies and midline abdominal incisions only. All wounds healed without complication. Wound breaking strength of the skin of the chest incisions was significantly greater (p < 0.05) in the control group (group 3) (52.6 lb) compared with groups 1 (38.0 lb) and 2 (34.8 lb). Wound breaking strength of the skin of the abdominal incisions was significantly greater (p < 0.05) in group 2 (50.4 lb) when paramedian incisions were made compared with group 1 (35.1 lb). Hydroxyproline content was similar for all groups and all incisions. We conclude that abdominal wound breaking strength is significantly greater when paramedian incisions are performed to harvest the inferior epigastric arteries. Harvesting bilateral internal thoracic, superior epigastric, and inferior epigastric arteries may lower sternal wound breaking strength.

Abdomen↗
PubMed1992

Combined maze procedure and septal myectomy in a septuagenarian.

A 75-year-old woman with refractory paroxysmal atrial fibrillation and hypertrophic obstructive cardiomyopathy underwent a successful combined maze procedure and septal myectomy. Postoperative episodes of atrial fibrillation and flutter occurred only during periods of bradyarrhythmia and did not recur with atrial inhibited pacing.

Aged↗
PubMed1992

Histological evaluation of the inferior epigastric artery in patients with known atherosclerosis.

Comparative histological studies have been performed on the various arterial conduits available for myocardial revascularization including the inferior epigastric artery which has recently become the focus of intense investigation. In this study, 10 patients with known risk factors for atherosclerotic disease had their inferior epigastric artery harvested and the entire specimen examined for the microscopical presence of atherosclerosis or its precursors. Histopathological findings that have been shown to be theoretically protective against the progression of atherosclerosis were observed. These include the paucity of fenestrae in the internal elastic lamina, no medical calcification, the absence of foam cells and the absence of intimal smooth muscle cells. No specimen had atherosclerotic disease and only 3 specimens showed changes consistent with minimal intimal hyperplasia. Morphometric analysis of the 3 diseased specimens revealed only minimal luminal narrowing. These findings suggest that the inferior epigastric artery may not be prone to atherosclerosis. Thus, the inferior epigastric artery appears to be a safe myocardial conduit and long-term patency can be anticipated.

Abdominal Muscles↗
PubMed1992

Electrophysiological effect of the maze procedure on canine sinoatrial node function.

The maze procedure is an operation that has had great initial success in curing atrial fibrillation. This procedure includes several right atrial incisions that may interrupt the integrity of the sinoatrial node or its arterial supply. To assess the effect of the maze procedure on sinus node function (SNF), the following studies were performed: sinus node recovery times (SNRT), corrected SNRT (CSNRT), CSNRT under autonomic blockade maximal heart rate and intrinsic heart rates. Thirty-four dogs underwent a right thoracotomy with cardiopulmonary bypass (CPB). The dogs were divided into three groups. Group 1 (n = 9), the sham group, underwent CPB without any incisions. Group 2 (n = 8) underwent CPB and one of the right atrial incisions. Group 3 (n = 18) underwent CPB and all three of the right atrial incisions. SNF was determined before and after the procedure. Groups 1 and 2 had no significant difference in measured SNF acutely after the procedure. In Group 3 the mean SNRT increased from 552 msec to 1,984 msec (P = 0.005). Sinus node dysfunction was corroborated by all studies. In the chronic studies, a trend toward recovery of SNF was observed. The maze procedure results in significant acute sinus node dysfunction. This dysfunction may resolve spontaneously over the ensuing months. Modifications of the maze procedure that avoid the sinus node or its blood supply area may reduce procedure related sinus node dysfunction.

Animals↗
PubMedDate not supplied

Wandering spleen with torsion: appearance on CT and ultrasound.

Wandering spleen is a rare entity which may present with symptoms suggestive of other, more common abdominal processes. Torsion of the long pedicle may occur causing abdominal pain. This article describes a case of wandering spleen diagnosed by computed tomography (CT). Liver spleen scintigraphy and sonography supported this diagnosis and suggested torsion. To our knowledge this is only the second case of this entity in which color flow and duplex Doppler findings have been reported.

Humans↗