Search PubMed⌕ Search

Biomedical subjects

H Laks

Publications and source records attributed to H Laks.

At least 271 records · Page 15Linked to original sources
PubMed1981

Patch reconstruction of the right ventricular outflow tract with pulmonary valve insertion.

Although pulmonary regurgitation is generally well tolerated, reconstruction of the right ventricular outflow tract and insertion of a pulmonary valve are indicated in some patients. This procedure was performed in 12 patients, ages 1 1/2-17 years (mean 10 years). Seven had tetralogy of Fallot; of these, one underwent primary repair with Glenn shunt takedown and six underwent repeat operations after previous repairs. Of these six, the major indication for reoperation was right ventricular outflow tract obstruction in four, tricuspid and pulmonary regurgitation in one, and a residual ventricular septal defect and patent shunt in one. Three had absent pulmonary valve syndrome and two had pulmonary atresia. There were no early complications or deaths in this series during a mean follow-up of 28 months. Repeat cardiac catheterization was performed in eight patients and revealed that the preoperative right ventricular-pulmonary artery gradient was reduced from 58 +/- 25 mm Hg to 11.6 +/- 7 mm Hg at rest postoperatively and was located at the level of the valve. This gradient increased with exercise or isoproterenol infusion to 31 +/- 9 mm Hg. Our experience suggests that right ventricular outflow tract reconstruction with porcine valve insertion can be safely performed with good hemodynamic results. This technique allows insertion of a larger porcine valve and avoids kinking and compression of a conduit behind the sternum.

Adolescent↗
PubMed1981

Dysfunction and thromboembolism associated with cardiac valve xenografts in adults.

Cardiac valve xenografts often fail relatively early in children. We analyzed the incidence of valve dysfunction and thromboembolism in 253 consecutive adult survivors who received 294 porcine xenograft valves (150 aortic, 125 mitral and 19 tricuspid) from June 1974 to December 1979 (41% of all adult valve replacements). Mean follow-up was 25.6 months (range 9-75 months). Valve dysfunction occurred in four of 294 xenografts (three in mitral position and one in tricuspid position), all four caused by recurrent endocarditis; these four patients survived reoperation and are doing well. Thromboembolism occurred in six of 294 xenografts, none in aortic or tricuspid positions of rhythm or anticoagulation. Four of the six mitral xenografts associated with thromboembolism were in the 16 patients who had atrial fibrillation and received aspirin and dipyridamole but no warfarin (12% per patient-year), and two were in the 14 patients who were in sinus rhythm and were not taking medication, one of whom had recurrent Candida endocarditis. No thromboembolism occurred in mitral xenografts with sinus rhythm and antiplatelet agents. Thromboembolism did not occur in patients who were in atrial fibrillation and receiving warfarin anticoagulation. Late death (30 of 253) was unrelated to valve dysfunction, and only one death resulted from thromboembolism. This study showed excellent xenograft performance for as long as 75 months. Valve dysfunction occurred only with recurrent endocarditis, and thromboembolism occurred after mitral replacement, especially in patients who were in atrial fibrillation and were not receiving anticoagulants.

Adult↗
PubMed1981

Randomized comparison of the modified wire-guided and standard intra-aortic balloon catheters.

We have designed a modified intra-aortic balloon (IAB) catheter to facilitate balloon insertion and minimize the complications of vascular dissection, perforation, and thrombosis. The modified balloon catheter is fabricated of a new polyurethane, Avcomat-100; it has a central lumen which allows for pressure monitoring, contrast injection, and introduction of a guide-wire under fluoroscopic control. In a randomized study, we compared the modified balloon with the standard Avco balloon catheter. Eighteen patients were randomized, 10 to receive a standard balloon catheter (control group) and eight to receive a modified balloon catheter. In two of the 10 patients assigned to the control group, introduction of the standard catheter failed but a central-lumen balloon was successfully introduced using the guide wire. A guide wire was needed for introduction of the modified balloon in three of the eight patients assigned to the central-lumen catheter group. The Avcomat-100 catheter material was less thrombogenic, with a lower rate of femoral thrombosis--20% in the control group and 0% in the central-lumen group. Scanning electron miroscopy also showed a reduced area of catheter surface covered with fibrin and clot. This study demonstrates the safety, decreased thrombogenicity, and increased facility of insertion of this new balloon catheter.

Adult↗
PubMed1981

Importance of edema and compliance changes during 24 hours of preservation of the dog heart.

The development of myocardial edema and the changes in compliance during long-term preservation and reperfusion of 10 dog hearts were studied. Krebs solution, modified by the addition of potassium chloride (20 mEq/L), was used for 24 hours of low-pressure perfusion (15 mm Hg), at 4 degrees C. The hearts then were reperfused with the use of a support dog. Gravimetric heart water of myocardial biopsy tissue increased from control values of 78.0 +/- 0.8 to 82.8 +/- 0.6 ml/100 gm at 1 hour (p less than 0.01) and to 84.2 +/- 0.3 ml/100 gm after 24 hours of preservation (p less than 0.05 compared to 1 hour). After reperfusion, heart water decreased to 82.8 +/- 0.3 ml/100 gm (p less than 0.05). Passive compliance during preservation, obtained using an inflatable intraventricular balloon, decreased from 1.49 +/- 0.03 ml/mm Hg at 1 hour to 0.65 +/- 0.14 ml/mm Hg at 24 hours (p less than 0.05). High-energy phosphate levels were unchanged at 1 and 24 hours of preservation. Light and electron microscopy at 24 hours of preservation showed marked pericapillary edema and excellent preservation of intracellular structures. During reperfusion, ventricular function curves and dp/dt (2,841 +/- 581 mm Hg/sec) were comparable to previously reported control values. Passive compliance at 24 hours correlated with the diastolic compliance during reperfusion (p less than 0.01). The change in passive compliance during preservation also correlated with the change in coronary vascular resistance, a previously reported index of myocardial viability (p less than 0.05). This study has shown that the change in passive compliance of the heart during perfusion correlates with the adequacy of myocardial preservation and provides an additional index of preserved heart viability.

Adenine Nucleotides↗
PubMed1980

Clinical experience with cold blood as the vehicle for hypothermic potassium cardioplegia.

Intermittent cold ischemic arrest was compared with hypothermic potassium cardioplegia using cold blood as the vehicle in two consecutive series of patients having isolated coronary bypass grafting. Between January 1, 1977, and June 30, 1977, 196 patients were operated on using cold ischemic arrest. The incidence of perioperative infarction was 14.3%, and mean total myocardial ischemia time was 42 +/- 1.2 minutes. From July 1, 1977, to June 30, 1978, there were 428 operations done using cold blood with potassium. The incidence of perioperative infarction was 5.6% (p less than 0.005), and the mean total myocardial ischemic time was 80 +/- 2.1 minutes. In the five years prior to this study, the incidence of perioperative infarction was constant at 13% while operative mortality was declining from 5 to 1% and the need for postoperative myocardial support was declining also. Use of cold blood potassium cardioplegia compared with cold ischemic arrest for myocardial protection during coronary artery operations has significantly reduced the incidence of perioperative infarction while doubling cross-clamp time.

Aspartate Aminotransferases↗
PubMed1980

Results of right atrial to right ventricular and right atrial to pulmonary artery conduits for complex congenital heart disease.

The Fontan procedure was initially proposed for tricuspid atresia (TA). We describe our experience with modifications of this operation and its application to previously uncorrectable congenital lesions. From 1975 to 1979, 26 patients have undergone a Fontan-like procedure, at a mean age of 14 years (range: 3 months to 23 years). Nineteen patients had TA, one patient had mitral atresia, four patients had a univentricular heart, one patient had a "criss-cross" heart, and one patient had pulmonary atresia. Previous procedures included eight Glenn shunts, 18 systemic to pulmonary artery (PA) shunts, two PA bands, and two atrial septectomies. Thirteen patients underwent right atrial (RA) to PA connections, with a valved conduit in nine patients and without in four. Two patients had simultaneous Glenn shunts. Thirteen had RA to right ventricular (RV) conduits, with a valve in 12 patients and without in one. There were five early deaths (<30 days, 19%) and no significant difference between the RA to PA connection (four deaths of 13) versus the RA to RV connection (one death of 13). The mortality rate was higher in patients undergoing RA to PA connection without valved conduit (one death of nine with a valve, three deaths of four without, p < 0.05), while the Glenn shunt did not affect mortality (one death of seven with, three of six without, p < 0.1). There were no late deaths (mean follow-up: 24 months). Seven patients underwent recatheterization with a mean RA pressure of 14 mmHg (range: 9--25 mmHg). Thus, the "Fontan" procedure can be done with an acceptably low mortality with good functional results, both for TA and other complex lesions.

Adolescent↗
PubMed1980

A cosmetically acceptable incision for the median sternotomy.

The median sternotomy incision has become the routine approach for most cardiac surgical procedures. This generally gives a poor cosmetic result. In certain patients, particularly those who are asymptomatic and undergoing short, low-risk procedures, cosmetic considerations are of relatively greater importance. We describe a transverse skin incision which gives adequate exposure for the median sternotomy. It has been used successfully in 40 female patients. This technique provides a cosmetically acceptable incision for the median sternotomy approach.

Adult↗
PubMed1980

Left atrial--left ventricular conduit for relief of congenital mitral stenosis in infancy.

Severe congenital mitral stenosis in the infant poses a difficult problem. We present the case history of an infant in whom a left atrial--left ventricular apical conduit was used to bypass a severely hypoplastic mitral valve. Associated coarctation of the aorta, patent ductus arteriosus, and ventricular septal defect were corrected at the same time. This method of circumventing the mitral valve offers a new approach to the relief of congenital mitral hypoplasia in small infants.

Aortic Coarctation↗
PubMed1979

Surgical principles and polytetrafluoroethylene.

This report describes a 24-month follow-up in 100 consecutive polytetrafluoroethylene (PTFE) arterial grafts. Although initial results were superb, a continued follow-up has showed extremely high closure rates for femoropopliteal and femorotibial grafts. The primary reason for this high attrition rate is thought to be stasis. We believe that PTFE is clearly the best synthetic arterial replacement available, but the material does not approach the autogenous saphenous vein in terms of long-term patency. Therefore, in spite of its many advantages, we do not recommend the elective use of PTFE for peripheral small-vessel bypass.

Bioprosthesis↗
PubMed1979

Revascularization of the right coronary artery.

This study was undertaken to evaluate revascularization of the right coronary artery with regard to factors that enter into the decision to graft less significant lesions, such as graft flow, graft patency and progression of proximal disease. The results of grafting the right coronary artery were studied in 23 patients with lesions reducing luminal diameter by less than 50 percent (Group 1), 35 patients with luminal narrowing of 50 to 70 percent (Group 2) and 112 patients with greater than 70 percent luminal narrowing (Group 3). At operation there was no significant difference in saphenous vein graft flows among the three groups. Postoperatively the mean follow-up period was 20, 27 and 26 months, respectively. Graft patency was not significantly different among the three groups. Progression of the proximal lesion was studied and compared with that in 71 ungrafted right coronary arteries, 60 with less than 50 percent stenosis and 11 with more than 50 percent stenosis. Among vessels with less than 50 percent narrowing, the proximal lesion showed progression in 26 percent of the ungrafted vessels and in 83 percent of the grafted vessels (P less than 0.005); progression to total occlusion occurred in 3 percent of the former and in 28 percent of the latter (P less than 0.005). Progression to total occlusion was more frequently associated with a patent than with an occluded graft (P less than 0.05). The occurrence of significant progression in ungrafted vessels and the lack of effect on graft patency of the severity of the proximal disease suggest that revascularization of less significant lesions may be of value. However, the resultant increase in progression of proximal disease makes the patient dependent on the long-term patency of the vein graft.

Cardiac Catheterization↗
PubMed1979

Long-term results of myocardial revascularization.

During 1970 to 1977, among 1,733 patients who underwent isolated coronary bypass grafting, the operative mortality was 2.5 percent. Actuarial 5 year survival is 88.1 percent. At an average follow-up of 46 months (range 13 to 108), 90 percent of patients remain angina-free or with symptomatic improvement. The 5 year survival rate of patients with single vessel coronary artery disease is 97.9 percent. In patients with multivessel disease, operative survival appears to be favorably influenced by the presence of normal preoperative ventricular function. Late survival is significantly better in patients with multivessel disease with normal preoperative ventricular function or with complete revascularization. Risk of perioperative myocardial infarction has been appreciably reduced by the introduction of cold potassium chloride cardioplegia. Late myocardial infarction has occurred at an average annual risk of 1.46 percent. These data show that long-term survival and a small incidence of late myocardial infarction after myocardial revascularization are more likely in patients who undergo complete revascularization before significant left ventricular myocardial damage has occurred.

Adult↗