Search PubMed⌕ Search

Biomedical subjects

H Laks

Publications and source records attributed to H Laks.

At least 217 records · Page 12Linked to original sources
PubMed1988

Systemic-to-pulmonary collateral vessels and shunts: treatment with embolization.

Abnormal collateral vessels develop frequently in patients with right ventricular outflow or pulmonary artery obstruction. Surgery is usually used to obliterate these vessels but may be difficult, involve prolonged operative time, or require a different thoracotomy than that used for correction or palliation of the cardiac anomaly. Sixteen trans-catheter embolization procedures were performed in 15 patients with systemic-to-pulmonary collateral vessels and shunts. In eight embolization procedures performed because of congestive heart failure or low oxygenation, clinical improvement was obtained in seven. In all six patients who underwent embolization preoperatively, the outcome of surgical correction or palliation was satisfactory. Hemorrhage ceased in the two patients with hemoptysis. There were two complications, one transient loss of femoral pulse and one segmental pulmonary infarction. Embolization is a useful adjunct to surgery and medical management of patients with systemic-to-pulmonary collateral vessels and shunts.

Adolescent↗
PubMed1988

Monocyte migration into the subendothelial space of a coculture of adult human aortic endothelial and smooth muscle cells.

Human aortic endothelial cells (EC) and smooth muscle cells (SMC) were isolated and used to form a multilayer of EC-SMC separated by a layer of collagen. SMC and/or collagen layers exerted minimal effects on Na+ transport but impeded the transport of LDL. The presence of an endothelial monolayer markedly reduced the transport of Na+ and LDL. When monocytes were presented to the complete coculture, in the absence of added chemoattractant, one monocyte entered the subendothelial space for every one to three EC present. In contrast, neither collagen nor SMC plus collagen nor EC plus collagen induced comparable monocyte migration. Despite massive migration of monocytes into the coculture, no significant alteration in Na+ transport was observed. LDL transport into the preparation during massive monocyte migration increased modestly, but this was far less than the amount of LDL transported in the absence of an endothelial monolayer. We conclude that (a) the endothelial monolayer was the principal permeability barrier, (b) a substantial migration of monocytes occurred in the absence of added chemoattractant when both EC and SMC were present in the coculture, (c) endothelial barrier function was largely maintained after monocyte migration; and (d) these experiments indicate the need to study all three cell types (monocytes, EC, and SMC) together to understand the complex interactions that occur between these cells.

Adult↗
PubMed1988

Cardiac transplantation. Selection, immunosuppression, and survival.

Cardiac transplantation has evolved from an experiment to an accepted therapy for severe heart failure. Increasing competition for donor organs mandates a greater emphasis on selection and timing for transplantation and paradoxically forces more reliance on aggressive medical therapy for all patients after evaluation. The growth of recipient and donor pools may enhance the opportunity for assessing histocompatibility, for which distinguishing between autoantibodies and human leukocyte antigen-determined reactivity is important, and some general nonresponders may be detected. Therapy with cyclosporine has improved the outcome after transplantation, but further refinement is needed, perhaps with pharmacologic synergy, to minimize nephrotoxicity and maximize specific immunosuppression. Survival is more than 80% at 1 year, after which the incidence of acute rejection and infection declines and accelerated atherosclerosis becomes prominent. Although resuming employment is not always possible, the overall quality of life is excellent after cardiac transplantation.

Cyclosporins↗
PubMed1988

Effects of acute hypoxia and reoxygenation in a blood-perfused neonatal heart model.

Newborn (less than 4-day old) piglet hearts (n = 7) were isolated and perfused with blood from a support pig. With use of a reservoir and membrane oxygenator, each heart was perfused for 90 minutes with blood at an O2 saturation of 40% and a pH of 7.4-7.5, at a left atrial pressure of 9 mm Hg, and at an aortic root pressure of 80 mm Hg. Blood saturation was increased to 100%, and the left atrial pressure decreased to 6 mm Hg for 60 minutes. Minute work indexes were calculated for each heart before hypoxia, every 30 minutes during hypoxia, and at 30 and 60 minutes of reoxygenation. Control hearts (n = 8) were treated in an identical fashion, but O2 saturation was maintained at 100%. Myocardial function decreased in the neonatal hearts exposed to hypoxia and reoxygenation. Control hearts did not suffer any significant decrease in function. Nucleotide levels were similar in both groups at the completion of the experiment. Anaerobic metabolism was demonstrated in the hypoxic hearts by net release of lactic acid during the period of hypoxia. This model can be used to study methods of intervention in the working hypoxic neonatal heart.

Acute Disease↗
PubMed1988

Long-term neonatal heart preservation.

UNLABELLED: Donor availability is a major limiting factor in neonatal heart transplantation. Prolonging donor heart preservation would facilitate distant heart procurement. Forty-two neonatal (1 to 5 days) piglet hearts in seven groups were arrested with cold cardioplegic solutions, stored for 12 hours at 4 degrees C in storage solutions, and reperfused with blood from an adult support pig. The cardioplegic solutions used were a crystalloid solution with potassium chloride 30 mEq/L and bicarbonate (Stanford), the Stanford cardioplegic solution with the addition of calcium (1.2 mmol/L), or an intracellular solution (Sacks) with added glucose. Storage solutions were normal saline, Sacks II, or Sacks II with glucose 20 gm/L. Reperfusion was done with normal blood or modified blood for 20 minutes with superoxide dismutase, catalase, aspartate, glutamate, citrate-phosphate-dextrose, potassium, tromethamine, and 50% dextrose followed by normal blood. Evaluation of stroke work index after 60 minutes of recovery (as percent of control) was performed using the isolated, blood perfused, working heart preparation in all groups: Group I (Stanford cardioplegia, saline storage, normal blood reperfusion) had a recovery of 11%; group II (Stanford + calcium, saline, normal blood) 8%; group III (Stanford + calcium, saline, modified blood, superoxide dismutase 35,000 U/L, catalase 35,000 U/L) 37%; group IV (Stanford + calcium, Sacks II, modified blood, superoxide dismutase 35,000 U/L, catalase 35,000 U/L), 47%; group V (Stanford + calcium, Sacks + glucose, modified blood, superoxide dismutase 35,000 U/L, catalase 105,000 U/L) 89%; group VI (Stanford + calcium, Sacks + glucose, modified blood, superoxide dismutase 150,000 U/L, catalase 150,000 U/L) 107%; group VII (Sacks + glucose, Sacks + glucose, modified blood, superoxide dismutase 35,000 U/L, catalase 105,000 U/L) 115%. CONCLUSIONS: The neonatal heart stored hypothermically for 12 hours tolerates normal blood reperfusion poorly. Modified blood reperfusion markedly improves the recovery. Complete functional recovery was achieved by the intracellular Sacks plus glucose storage solution and modified blood reperfusion with oxygen-derived free radical scavengers (high catalase). Extended preservation of the neonatal heart is feasible.

Animals↗
PubMed1987

Magnetic resonance imaging of the thoracic aorta.

Forty-one patients with a variety of suspected aortic lesions underwent magnetic resonance imaging (MRI) of the thoracic aorta. Patients were separated into 2 groups: Group A included 19 patients who underwent MRI after arteriography for comparison purposes and were evaluated retrospectively. Surgical confirmation was obtained in 9 of these patients. Group B included 22 patients who were studied prospectively because of abnormal chest x-ray, ultrasound or computerized tomographic findings and did not undergo arteriography before MRI. Two patients from this group had surgery. In group A, MRI correlated with the surgical or angiographic findings in 18 of 19 patients (95%). In group B, MRI was considered of diagnostic quality in all patients and no other invasive or noninvasive imaging modalities were needed for diagnosis and treatment. Thus, MRI will replace arteriography in a large proportion of patients with suspected thoracic aortic lesions.

Aorta, Thoracic↗
PubMed1987

Mitral regurgitation after cardiac transplantation.

The contribution of the left atrium to mitral valve competence was assessed using the model of altered atrial size and geometry created by atrial anastomosis during cardiac transplantation. Sixteen patients underwent Doppler and 2-dimensional echocardiography after orthotopic transplantation. Mitral regurgitation was present in 14 of 16 patients. Left atrial geometry was uniformly abnormal, in a "snowman" configuration. Compared with 16 normal control subjects, the transplanted left atria were dilated (23 +/- 6 vs 13 +/- 3 cm2 during ventricular systole, p less than 0.001). Mitral valve anular diameter indexes, anular systolic reduction and ventricular function were normal in both groups. Ventricular volumes were small in the transplanted heart relative to donor body size (15 +/- 5 vs 20 +/- 8 cm3/m2 in systole, p less than 0.05). The ratio between ventricular length and anular diameter was smaller in the transplant patients (0.87 +/- 0.1 vs 1.0 +/- 0.2, p less than 0.05). In the presence of abnormal left atria, mitral regurgitation may occur without other structural abnormalities of the mitral apparatus. This study suggests that the left atrium plays an important role in mitral valve competence for primary cardiac disease associated with left atrial enlargement, even in the absence of intrinsic mitral valve disease or left ventricular dysfunction.

Echocardiography↗
PubMed1987

Results of the Senning procedure in infants with simple and complex transposition of the great arteries.

Because of interest in the arterial switch operation, recent experience with the Senning operation in patients with simple and complex transposition of the great arteries (TGA) was examined. Between 1982 and 1985, 35 patients with simple TGA (group I) and 10 patients with complex TGA (group II) underwent a Senning operation. Mean duration of follow-up was 14 months for group I and 24 months for group II. In group I, 1 patient died early and no patient died late; infrequently, right ventricular dysfunction, tricuspid regurgitation, baffle obstruction or arrhythmias occurred. In group II, no patient died early and 3 died late. In addition, many patients required prolonged digoxin therapy. Because the arterial switch operation has a high early mortality risk and an undetermined long-term morbidity and mortality risk, the Senning operation (or other venous switch operations) is considered the preferred surgical approach for simple TGA. In contrast, an arterial switch operation is performed in patients with complex TGA (without subpulmonic obstruction). Comparison of the early and late morbidity and mortality of the arterial vs the venous switch operation may be helpful in selecting the appropriate surgical approach to complex TGA.

Female↗
PubMed1987

Coarctation repair without cardiac catheterization in infants.

Of 35 infants who underwent an operation for coarctation of the aorta, 15 did not undergo cardiac catheterization before surgery. The diagnoses in all uncatheterized patients were made by clinical examination, chest radiography, ECG, and two-dimensional echocardiography combined with pulsed Doppler echocardiography. Associated anomalies diagnosed by two-dimensional/Doppler echocardiography included a patent ductus arteriosus in all patients, bicuspid aortic valve in six, small ventricular septal defect in four, and complete common atrioventricular canal in one. In no instance was the diagnosis of coarctation in error. In addition, the clinical significance of the ventricular septal defect was judged correctly by two-dimensional echocardiography, and no patient required an early reoperation because of significant left-to-right shunt. Two significant lesions were missed in one patient each: mitral stenosis and aortic stenosis. These diagnoses were missed in patients who were first seen with either profound congestive heart failure or shock. Coarctation of the aorta and associated lesions can be diagnosed accurately by two-dimensional echocardiography. This permits proper patient management without the added risk of cardiac catheterization. Although mitral and aortic lesions may be missed because of low cardiac output, this does not result in management errors.

Aortic Coarctation↗
PubMed1987

A new technique for permanent pacemaker implantation in infants and children.

Permanent pacemaker implantation in the infant or young child presents the surgeon with many technical problems unique to this population. A new technique of implantation is described that was used successfully in 6 pediatric patients. The technique is simple to perform and gives very satisfactory results.

Child↗
PubMed1987

Thoracic surgery manpower: the fourth manpower study of thoracic surgery: 1985 report of the Ad Hoc Committee on Manpower of The American Association for Thoracic Surgery and The Society of Thoracic Surgeons.

Responding to a survey about their practice in 1985, 2,969 (70%) Board-certified thoracic surgeons provided data that were compared with data from manpower surveys in 1980 and 1976. (table; see text) Thoracic surgeons were most active between ages 35 and 54 years when they accomplished 61% of all general thoracic and 85% of cardiac operations. Surgeons older than 50 years performed significantly more general thoracic operations than younger surgeons, and the younger group performed significantly more cardiac operations than their older counterparts. Solo practice continued to decline. In smaller referral areas, the number of general thoracic procedures per surgeon increased, but the number of cardiac operations have decreased compared with 1980. Overall, general thoracic and cardiac operations increased, but peripheral vascular procedures and pacemaker insertions decreased in almost all nine census regions. Fewer general thoracic and cardiac operations were performed per thoracic surgeon in the western United States than in central and eastern regions. In response to questions about work load, 55% believed that their clinical activity was satisfactory, 42% operated too little, and 3% operated too much. The 363 non-Thoracic Board-certified surgeons who responded performed 14% of general thoracic and 8% of cardiac surgery in 1985. During the first half of the 1980s, our specialty certified an average of 134 thoracic surgeons annually, which is higher than the 120 surgeons per year estimated to meet the projected demand.

Adult↗
PubMed1987

Use of in situ pericardium for surgical relief of pulmonary venous obstruction following Mustard's operation.

A technique is described for relief of pulmonary venous obstruction following the Mustard procedure. The functional left atrium is enlarged by using the pericardium in situ. This is expected to allow for growth of the pericardial patch and to avoid recurrent obstructions. This technique has also been used in reoperations for systemic venous obstruction after enlargement of the systemic baffle with a patch.

Heart Atria↗
PubMed1987

Reduced narcotic requirement by clonidine with improved hemodynamic and adrenergic stability in patients undergoing coronary bypass surgery.

The authors examined the effect of clonidine, a preferential alpha 2-adrenergic agonist, upon narcotic requirements, hemodynamics, and adrenergic responses during the perioperative period in patients undergoing CABG surgery. Anesthesia was provided by sufentanil supplemented with isoflurane; sodium nitroprusside was given as needed for hemodynamic control. Ten patients received oral clonidine preoperatively at the time of premedication, and again intraoperatively by nasogastric tube. Another group of ten untreated patients were otherwise managed identically. Intergroup differences in required anesthetic and vasoactive drug doses and recovery times were measured and evaluated, as well as hemodynamics and plasma catecholamines prior to induction, after intubation, and at intervals intra- and postoperatively. Patients who received clonidine required less diazepam prior to induction, and received 40% less sufentanil during the anesthetic period, than did untreated controls. More control patients required the addition of isoflurane to prevent hypertension. Mean blood pressures and heart rates were elevated at many sampling points in patients not treated with clonidine. Four of the clonidine-treated group required atropine for treatment of bradycardia in the pre-incision period. Plasma catecholamines were significantly lower throughout most of the study period in patients treated with clonidine. After cardiopulmonary bypass and postoperatively, cardiac outputs were significantly higher in the treated group. Patients who had received clonidine were extubated significantly earlier, and fewer of them shivered postoperatively. We conclude that perioperative treatment with clonidine reduced narcotic and anesthetic requirements, improved hemodynamics, reduced plasma catecholamines, and shortened the period of postoperative ventilation in patients undergoing coronary artery surgery.

Anesthetics↗
PubMed1987

Myocardial protection in the neonatal heart. A comparison of topical hypothermia and crystalloid and blood cardioplegic solutions.

UNLABELLED: Myocardial protection achieved during 2 hours of ischemic arrest was evaluated in 45 isolated, blood perfused, neonatal (1 to 5 days) piglet hearts. Comparisons were made among five methods of myocardial protection: Group I, topical cooling; Group II, hyperosmolar (450 mOsm) low-calcium (0.5 mmol/L) crystalloid cardioplegia; Group III, St. Thomas' Hospital cardioplegia; Group IV, cold blood cardioplegia with potassium (21 mmol/L), citrate-phosphate-dextrose (calcium level 0.6 mmol/L), and tromethamine; and Group V, cold blood cardioplegia with potassium alone (16 mmol/L) (calcium level 1.2 mmol/L). Hemodynamic recovery (percent of the preischemic stroke work) after 30 and 60 minutes of reperfusion was 82.9% and 86.7% in Group I, 35.7% (p less than 0.0001) and 43.7% (p less than 0.0001) in Group II, 76.1% and 77.7% in Group III, 67.4% (p less than 0.05) and 60.6% (p less than 0.05) in Group IV, and 110.7% and 100.6% in Group V. CONCLUSIONS: Topical cooling is an effective method of myocardial protection in the neonate. Cold blood cardioplegia with potassium alone and a normal calcium level provides optimal functional recovery. The improved protection obtained with both crystalloid and blood cardioplegia with normal calcium levels suggests an increased sensitivity of the neonatal heart to the calcium level of the cardioplegic solution.

Animals↗
PubMed1986

Repair of aortic coarctation in the first three months of life: immediate and long-term results.

The optimum surgical procedure for treatment of coarctation of the aorta in the neonatal period remains controversial. To assess immediate and long-term results of using primarily the subclavian flap angioplasty procedure (SFA), we reviewed our initial 5-year experience. The average follow-up was 6 years. From 1977 to 1981, 25 infants under 3 months of age (1 to 86 days, mean 21) required emergency surgery for repair of coarctation of the aorta. Three groups of patients were identified. Group I consisted of 10 patients with or without patent ductus arteriosus. In group II, 10 patients had coarctation association with one or multiple ventricular septal defects (VSDs) without other congenital defects. In group III, 5 patients had coarctation associated with more complex congenital heart lesions. Twenty-three SFAs and two patch aortoplasties were performed. No patient with isolated VSD was banded. All patients except one in group III with an associated atrioventricular canal survived initial hospitalizations. Four late deaths occurred, all in patients with associated complex heart defects. There were three recurrent coarctations requiring surgery or balloon angioplasty (12%)--one in each group, with a total rate of 0.77 recurrences per 100 patient-months. SFA for coarctation in the neonatal period is a safe and effective operation with a low initial mortality (4%, 0-19%, 70% confidence limits) well tolerated in this group of ill patients. Long-term outcome is primarily related to the presence of associated complex congenital defects. Infants with VSD associated with coarctation did not require pulmonary artery banding unless primary intracardiac repair was not feasible.(ABSTRACT TRUNCATED AT 250 WORDS)

Aortic Coarctation↗