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Biomedical subjects

H Laks

Publications and source records attributed to H Laks.

At least 91 records · Page 5Linked to original sources
PubMed1997

Unbalanced atrioventricular septal defects.

Complete atrial ventricular septal defects (AV canal) generally have right and left valve components equally divided. However, in unbalanced AV canal either right or left ventricle dominance may occur. The spectrum may vary between those readily able to undergo biventricular repair at no increased risk to those requiring a single ventricle approach in cases with severe hypoplasia of the ipsilateral ventricle. The most challenging diagnostic cases fall within the gray area between the two ends of the spectrum, in which one ventricle is not clearly hypoplastic. Diagnostic modalities that are used to evaluate these ventricles include echocardiography and angiographic ventriculography using volume formulae. Magnetic resonance imaging (MRI) has also recently been found to be a useful technique with which further experience is being developed. Once the determination of a single ventricle physiology has been made, early intervention (ie, pulmonary artery banding) to protect both the pulmonary vasculature and the ventricular function is performed. Follow-up with catheterization and bidirectional Glenn should be completed usually by around 4 to 6 months of age. This palliation and subsequent Fontan completion has had good results based largely on two factors: ventricular dominance, left being better than right, and the absence of pulmonary vascular hypertension.

Aortic Valve Insufficiency↗
PubMed1997

Defining obesity in patients undergoing orthotopic heart transplantation: body mass index versus percent body fat.

We examined body mass index (BMI) as a proxy for percent body fat among 26 men and women successfully undergoing orthotopic heart transplantation. Percent body fat was determined by use of bioelectrical impedance techniques. We found that, although BMI was well correlated with percent body fat (r = 0.58, p < 0.01), use of a BMI of greater than 27 kg/m2 to define obesity potentially misclassified patients when compared with defining obesity as a percentage of body fat as both greater than 30% (BMI = 9 of 26 patients vs percent body fat = 6 of 26 patients) and greater than 40% (BMI = 9 of 26 versus percent body fat = 1 of 9). We conclude that percent body fat measurements are more methodologically appropriate means for J Heart Lung Transplant 1997;16:563-5.

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↗
PubMed1997

Experience of patients with end-stage heart failure who underwent heart transplant at UCLA.

From 1993 to 1997, nine Japanese heart transplant candidates were accepted by the University of California at Los Angeles (UCLA) Medical Center, because no donor heart was available in Japan from a brain-dead patient. In all nine heart transplant patients described in this investigation, the preoperative diagnosis was dilated cardiomyopathy. One patient underwent implantation with a Novacor left ventricular assist device (Baxter Japan, Tokyo, Japan) as a bridge to heart transplant. All patients survived surgery and for a long-term period. The actuarial 1-year and 3-year survival curves of these patients were both 100%. The postoperative functional status was New York Heart Association Class 1 in all patients (100%). Immunosuppressive triple drug therapy (azathioprine, steroids, and cyclosporine) was given in seven patients; in two patients, cyclosporine was withdrawn and replaced by FK506 due to refractory rejection. The incidence of acute rejection per patient of more than grade 3 according to the International Society for Heart and Lung Transplantation was 6% within 3 months and 4.5% in 3-6 months; there was no rejection episode more than 6 months after transplantation. Post-transplant coronary artery disease was seen in two patients. However, no disease progression was seen after diltiazem therapy. These results may encourage heart transplantation in Japan.

Adult↗
PubMed1996

Pretransplant panel reactive-antibody screens. Are they truly a marker for poor outcome after cardiac transplantation?

BACKGROUND: The effect of pretransplant sensitization on outcome after cardiac transplant has been controversial. Sensitization, defined as a positive panel-reactive antibody (PRA) screen in patients awaiting transplant, represents circulating antibodies to a random panel of donor lymphocytes (usually T lymphocytes). The significance of pretransplant circulating antibodies to B lymphocytes has not been reported, and many centers disregard its use. METHODS AND RESULTS: We retrospectively reviewed the pretransplant PRA screens for 311 patients who underwent cardiac transplant at our institution. The PRA screen was performed by use of the lymphocytotoxic technique treated with dithiothreitol to remove IgM autoantibodies. Patients with PRA > or = 11% against T or B lymphocytes had significantly lower 3-year survival (T lymphocytes, 39%; B lymphocytes, 56%) than those patients with PRA = 0% and PRA = 1% to 10% (T lymphocytes, 76% and 78%; B lymphocytes, 78% and 74%, respectively) (P < .001). For this high-risk group, the rejection episode tended to occur earlier than in those patients with PRA = 0% and PRA = 1% to 10% (T lymphocytes, 2.3 versus 4.0 and 3.8 months; B lymphocytes, 2.1 versus 4.1 and 3.4 months, respectively), and there were more clinically severe rejections that required OKT3 therapy. CONCLUSIONS: Cardiac transplant patients with pretransplant T- and/or B-lymphocyte PRA > or = 11% despite negative donor-specific crossmatch at the time of transplant appear to have earlier and more severe rejection with significantly lower survival after transplant surgery. Modification of immunosuppression in these high-risk patients may be warranted.

Adult↗
PubMed1996

Usefulness of banding of the pulmonary trunk with single ventricle physiology at risk for subaortic obstruction.

This study addresses the effects of early banding of the pulmonary trunk and subsequent management of subaortic obstruction on the attainment of acceptable pre-Fontan hemodynamics in patients with a single left ventricle and aorta arising from an outflow chamber. We report our experience with 26 patients seen at our institution between January 1984 and December 1994 with a diagnosis of double-inlet left ventricle or tricuspid atresia and transposed great arteries, who were initially managed with pulmonary artery banding in the first 6 months of life. Pulmonary artery band placement was performed at an age of 2.1 +/- 1.8 months (mean +/- SD). Associated aortic arch abnormalities were present in 8 patients (31%). There were 19 patients (73%) who underwent treatment with a Damus-Kaye-Stansel procedure or ventricular septal defect (VSD) enlargement for a significant subaortic gradient or morphologically small VSD, alone or in conjunction with a Glenn or Fontan procedure. Eighteen of 26 patients (69%) underwent cardiac catheterization to assess their candidacy for the Fontan operation. Of this group, 16 were classified as low to moderate risk and 2 as high-risk Fontan candidates, based on hemodynamic criteria. The cumulative mortality for the entire cohort was 19%. Our results suggest that this high-risk group of patients can undergo effective pulmonary artery banding as an initial palliative step, with subsequent intervention for subaortic ob- struction when it is documented or highly suspected, and that acceptable pre-Fontan hemodynamic parameters can be achieved.

Cardiac Catheterization↗
PubMed1996

Evidence of improved microvascular perfusion when using antegrade and retrograde cardioplegia.

BACKGROUND: The maximum degree of microvascular distribution of cardioplegic solution is considered important to achieve optimum myocardial protection. This study attempts to demonstrate that the addition of retrograde cardioplegia to antegrade cardioplegia improves overall microvascular perfusion. METHODS: Explanted human hearts (n = 6) were treated with cold cardioplegic arrest and bicaval cardiectomy. Blood cardioplegia (37 degrees C) containing colored microspheres (color A for antegrade, color B for retrograde) was simultaneously infused antegrade at a pressure of 80 mm Hg and retrograde at a pressure of 40 mm Hg for 2 minutes. The ventricular myocardium was then sampled at three sites to determine absolute and relative cardioplegic microvascular flow. RESULTS: Of the total microvascular capillary flow, 27% to 32% was found to be the contribution of retrogradely delivered cardioplegia. CONCLUSIONS: Despite being delivered simultaneously and at a lower pressure, retrograde cardioplegia contributed substantially to overall microvascular perfusion. This suggests that antegrade cardioplegia alone does not perfuse all available myocardial capillaries and that the addition of retrograde cardioplegia enhances overall microvascular distribution and perfusion.

Cardioplegic Solutions↗
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

MR imaging of surgical complications of systemic-to-pulmonary artery shunts.

Patients with a systemic-to-pulmonary artery shunt and positive findings on traditional imaging modalities such as chest X-ray, echocardiography, or cardiac angiography often can benefit from additional noninvasive imaging with magnetic resonance imaging (MRI). Diagnostic dilemmas encountered include: pseudoaneurysms, contained fluid collection (seroma) surrounding a shunt, and stenosis of the shunt anastomoses. MRI studies using traditional cardiac-triggered spin-echo (SE) imaging and the newer breathhold MRI studies with k-space segmented gradient-recalled echo (GRE) imaging can greatly help resolve diagnostic dilemmas. By combining different MR imaging techniques it becomes possible to clearly distinguish between pseudoaneurysms and seroma, to exclude an active leak and to sometimes visualize the distal anastomosis with more precision than conventional angiography. MRI is often able to add information needed for clinical decision making prior to surgical repair.

Adolescent↗
PubMed1996

Issues in surgical treatment of endocarditis including intraoperative and postoperative management.

Patients with infective endocarditis who require surgical intervention can be divided into four separate groups, in order of incidence: (1) patients with underlying acquired or congenital cardiac lesions or valvar abnormalities, (2) patients with preexisting prosthetic valves, (3) patients with nosocomial infections who are immunosuppressed, and (4) older patients with infection risk or patients with indwelling deep venous catheters. The surgical management for these individual groups and for specific valve lesions is discussed, along with illustrative case studies.

Aged↗
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↗