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Biomedical subjects

H Laks

Publications and source records attributed to H Laks.

At least 199 records · Page 11Linked to original sources
PubMed1990

Partial biventricular repair for double-outlet right ventricle with left ventricular hypoplasia.

The presence of left ventricular hypoplasia in double-outlet right ventricle may increase the risk of biventricular repair and Fontan procedures. The hypoplastic left ventricle of an 11-year-old girl with complex double-outlet right ventricle was successfully incorporated in a modified biventricular repair by Dacron patch closure of the ventricular septal defect, diversion of venous return of the inferior vena cava to the mitral valve with an intraatrial baffle, insertion of a left ventricular apex to pulmonary artery valved aortic homograft, and diversion of residual systemic venous return directly to the lungs with a bidirectional superior vena cava to pulmonary artery shunt. Postoperatively, the systemic venous atrial pressure was 6 mm Hg and the pulmonary artery pressure was 14 mm Hg. This method is proposed as a partial biventricular repair hemodynamically superior to the Fontan procedure, although aortic homograft revision may be required in the future.

Blood Vessel Prosthesis↗
PubMed1990

A new technique for delivering antegrade/retrograde blood cardioplegia without right heart isolation.

We report our updated experience with combined antegrade/retrograde cardioplegia using a self-inflating/deflating balloon cannula that allows rapid transatrial retrograde coronary sinus cannulation (10-15 s) without right heart isolation. This permits routine single venous cannulation and optimizes myocardial protection when combined with antegrade cardioplegia. Two hundred fifty-five consecutive patients underwent antegrade/retrograde cardioplegia. Initial antegrade blood cardioplegia caused immediate arrest (less than 1 min), and the cardioplegic dose was divided equally between antegrade and retrograde delivery. Included are 173 isolated CABG patients (39 with either extending infarction, cardiogenic shock, or ejection fraction less than 20%), and 37 coronary reoperations, 67 with aortic and/or mitral valve procedures, 3 with arrhythmia surgery, and 7 children (VSD, Rastelli, Konno, etc). Septal temperature in patients with LAD occlusion fell to 11.6 degrees C +/- 0.5 after retrograde vs only 16.1 degrees C +/- 3 after antegrade cardioplegia (p less than 0.05). Overall hospital mortality was 2.8% and no complications followed transatrial retrograde coronary sinus cannulation. Antegrade/retrograde cardioplegia allowed retrograde flushing of debris in redo coronary operations, produced immediate arrest with low cardioplegic volumes, improved cardioplegic distribution during IMA grafting, allowed aortic and mitral valve procedures to proceed uninterrupted, and ensured distribution in unforeseen aortic insufficiency. Antegrade/retrograde cardioplegia is now used routinely in all adult and in many pediatric operations because of its speed, safety, and simplicity.

Adolescent↗
PubMed1990

Ventilatory and diffusion abnormalities in potential heart transplant recipients.

Few data are available concerning pulmonary function in patients with severe chronic congestive heart failure. Of 315 patients evaluated for potential cardiac transplantation at UCLA, 132 underwent pulmonary function tests. The latter patients had severe heart failure with a mean left ventricular ejection fraction of 19 percent and mean cardiac index of 2.1 L/min/m2. Diffusion impairment either alone or combined with restrictive and/or obstructive ventilatory defects occurred in 67 percent of the patients evaluated. Diffusion impairment occurred as the sole abnormality in 31 percent of the patients and in combination with a restrictive ventilatory defect in 21 percent. A reduction in diffusing capacity has not been previously described as a frequent finding in patients with chronic congestive heart failure. In contrast to other studies involving patients with acute heart failure, obstructive ventilatory defects were uncommon. None of the lung function abnormalities was associated with smoking status, prior drug use, chest roentgenographic changes, hemodynamic findings, or clinical features, including duration of congestive heart failure. The mechanism for the diffusion impairment is unclear but could be due to chronic passive congestion with pulmonary fibrosis and/or recurrent pulmonary emboli. Recognition of diffusion impairment as a common finding in patients with severe chronic congestive heart failure who are candidates for heart transplantation is important for proper interpretation of possible post-transplant changes in diffusing capacity due to other causes.

Adult↗
PubMed1990

Thirty-year follow-up of superior vena cava-pulmonary artery (Glenn) shunts.

The first superior vena cava-pulmonary artery shunt (Glenn shunt) in our series was performed in February 1958. From then through September 1988, 91 patients have undergone this procedure for a wide variety of congenital defects. We here report follow-up data available on all patients. Ages ranged from 2 days to 46 years (mean 6.8). Diagnoses were as follows: tricuspid atresia, 27; single ventricle, 22; tetralogy of Fallot, 14; D-transposition of the great arteries, ventricular septal defect, and pulmonary stenosis, 9; D-transposition, 5; Ebstein's anomaly, 4; pulmonary atresia + intact septum, 4; and others, 6. The hospital mortality rate was 7.7% (one death in the last 53 patients, 1.9%). Five deaths occurred in patients less than 6 months old. There were 20 late deaths (22%) with actuarial survival rates of 84% and 66% at 10 and 20 years, respectively. Pulmonary arteriovenous fistula formation was seen in 18 patients (19.7%), six of whom have undergone therapeutic embolization with improvement in saturation. The prevalence of pulmonary arteriovenous fistula increases with time after shunt. No long-term shunt thrombosis or stricture formation was seen. Fifty percent of shunts were still functioning at 20 years. Palliation was limited because of decrease in blood flow to the contralateral pulmonary artery, collaterals between the inferior and superior venae cavae, and pulmonary arteriovenous fistula formation. Improvement in saturation was obtained in eight otherwise inoperable patients by creation of a right axillary arteriovenous fistula up to 19 years after the Glenn shunt. Three patients had conversion of a Blalock-Taussig shunt to a Glenn shunt with improvement in congestive heart failure. Twenty-six patients have undergone a Fontan procedure with two deaths. Compared with the group having a Fontan procedure without a prior Glenn operation, there was no difference in early or late mortality. Thirty years after a Glenn shunt, the first patient in this series is working full time after having undergone a modified Fontan procedure in 1981. We conclude that the Glenn connection, usually with supplemental procedures to enhance oxygenation, has provided excellent physiologic palliation with low mortality up to 30 years with no late thrombosis or stricture formation. The incidence of pulmonary arteriovenous fistula increases with time and can be effectively treated with embolization. Physiologic repair after the Glenn shunt carries a low mortality. Although currently used infrequently, superior vena cava-pulmonary artery shunting remains a useful method of palliation in selected patients.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1990

Cardiac transplantation: the UCLA experience 1984 to 1990.

The international experience has documented the therapeutic value of cardiac transplantation in the management of carefully selected patients with endstage heart disease. The UCLA program's experience over the years 1984 to 1990 mirrors these results, establishing heart transplantation as an accepted form of therapy that offers extended survival and improved quality of life compared to alternative means of treatment. Criteria of eligibility for recipient candidates have become less restrictive, most notably the expansion of age limits to include increasingly older patients. Seventy-three patients over 55 years of age underwent heart transplantation in this series, with actuarial survival results comparable to that achieved in adult patients 55 years of age and under (68.5% vs 74.7% at 4 years, respectively). Twenty-one children between the ages of 7 months and 17 years have undergone cardiac transplantation at UCLA with survival results comparable to that of our adult population (74.3% vs 76.5% actuarial survival at 3 years, respectively). Continued efforts aimed at the development of improved means of immunosuppression as well as better methods for the detection of rejection are needed if these results are to be significantly improved.

Adult↗
PubMed1990

Effect of PCO2-adjusted pH on the neonatal heart during hypothermic perfusion and ischemia.

The effect of pH regulation on the function of the isolated neonatal heart during continuous hypothermic perfusion and arrest was tested in 3- to 6-day-old piglet hearts. Three groups of hearts were perfused from an adult support pig, with pH varied by a carbon dioxide/oxygen gas exchanger and temperature controlled by a heat exchanger. After control function studies were obtained at normothermia with a pH of 7.4, the hearts were cooled over 15 minutes to 10 degrees C. Hypothermic perfusion was maintained for 1 hour, followed by rewarming to 37 degrees C. In group 1 (n = 5), the alpha stat (neutral) model, the blood perfusate was maintained at a pH of 7.4 (calculated at 37 degrees C). In group 2, the alkaline model, the pH was maintained at 7.9, and in group 3, the pH-stat (acid) model, the pH was maintained at 7.0. In addition, the effect of 1 hour of hypothermic ischemia after hypothermic perfusion at a pH of 7.0 was evaluated in five hearts (group 4). After rewarming no significant difference was noted in functional recovery (group 1 = 93% +/- 5%, group 2 = 92% +/- 6%, group 3 = 96% +/- 5%, and group 4 = 95% +/- 2%), oxygen consumption, coronary resistance, lactate extraction, and myocardial extravascular water content. We conclude that neonatal heart function is resistant within the range of this study to changes in pH caused by changes in carbon dioxide tension during hypothermic perfusion and ischemia.

Acid-Base Equilibrium↗
PubMed1990

A new simplified method of optimizing cardioplegic delivery without right heart isolation. Antegrade/retrograde blood cardioplegia.

We report our initial experience with antegrade/retrograde cardioplegia using a self-inflating/deflating balloon cannula that allows rapid transatrial retrograde cannulation of the coronary sinus (10 to 15 seconds) without right heart isolation and permits routine single venous cannulation. We subjected 141 consecutive adult patients and nine children to antegrade/retrograde cardioplegia using rapid transatrial insertion of the Retroplegia cannula (Research Medical, Inc., Salt Lake City, Utah). Single venous cannulation was used in 116 patients having coronary artery bypass grafting or aortic valve replacement, or both. Initial antegrade blood cardioplegia caused immediate arrest (less than 1 minute) and the cardioplegic dose was divided equally between antegrade and retrograde delivery. Included are 95 patients having isolated bypass grafting (34 with extending infarction, cardiogenic shock, or ejection fraction less than 20%); 19 having coronary reoperations, 42 with aortic or mitral valve procedures, or both; and nine children having repair of congenital defects (e.g., repair of ventricular septal defect, Rastelli operation, Konno operation). Septal temperature in patients with occlusion of the left anterior descending coronary artery fell to 11.5 degrees +/- 0.5 degrees C after retrograde cardioplegia versus only 16 degrees +/- 3 degrees C after antegrade cardioplegia (p less than 0.05). The overall hospital mortality rate was 2% and no complications followed transatrial retrograde cannulation of the coronary sinus.

Adolescent↗
PubMed1989

Modified reperfusate after long-term preservation of the heart.

Warm (30 degrees C) blood cardioplegia (K = 22 mEq/L) with glutamate (26 mmol/L) as a reperfusate was compared with unmodified blood reperfusion after prolonged hypothermic storage of the isolated canine heart. After cardioplegic arrest, three groups of hearts (n = 5 each) were excised and stored at 2 degrees C. In groups 1 and 2, reperfusion with unmodified blood was undertaken after six and 24 hours of storage, respectively, and in group 3, reperfusion with modified warm blood cardioplegia containing glutamate was administered after 24 hours of storage. After reperfusion, no significant difference in left ventricular developed pressure was noted between groups 1 (110 +/- 15 mm Hg), 2 (127 +/- 14 mm Hg), and 3 (98 +/- 13 mm Hg). Similarly, no difference in maximum rate of rise of left ventricular pressure was noted between groups 1 (1,456 +/- 171 mm Hg/s), 2 (1,905 +/- 395 mm Hg/s), and 3 (1,450 +/- 291 mm Hg/s). Group 3 (modified reperfusate) had improved diastolic compliance compared with group 2 (0.776 mm Hg/mL versus 1.395 mm Hg/mL; p less than 0.02). We conclude that our modified reperfusate improves diastolic function after 24 hours of hypothermic storage, but does not result in improved systolic function.

Animals↗
PubMed1989

Improved neonatal heart preservation with an intracellular cardioplegia and storage solution.

The optimal conditions for preservation of the neonatal heart for transplantation remain uncertain. An isolated, working neonatal piglet heart model was used to compare a standard extracellular-like cardioplegic solution followed by storage at 4 degrees C in normal saline for 12 hr (n = 8) to cardioplegia and storage at 4 degrees C for 24 hr in an intracellular-like solution (n = 7). Seven of eight hearts in the 12-hr Extracellular Group failed to regain function, with a maximum stroke work index (SWI), developed at a left ventricular end-diastolic pressure (LVEDP) of 9 mm Hg of 0.91 +/- 0.30 x 10(3) erg/g (mean +/- standard error of the mean), 7.1% of nonpreserved control hearts. In contrast, all hearts arrested and stored for 24 hr in the intracellular solution regained function with a maximum SWI, again at a LVEDP of 9 mm Hg of 9.51 +/- 1.98 X 10(3) erg/g, 73.7% of control (P less than 0.05). Ultrastructural changes seen by electron microscopy paralleled the functional results. We conclude that an intracellular arrest and storage solution may be superior to conventional solutions for extended preservation of the neonatal heart.

Animals↗
PubMed1989

Surgical options for complex transposition of the great arteries.

Between September 1976 and November 1987, 53 patients underwent surgical treatment by the same surgeon for "complex transposition of the great arteries" with ventricular septal defect or severe left ventricular outflow tract obstruction, or both. Six patients with transposition and left ventricular outflow tract obstruction underwent atrial rerouting and direct relief of the left ventricular outflow tract obstruction. Twenty-two patients presented with transposition plus ventricular septal defect; 15 of these patients underwent atrial rerouting and ventricular septal defect closure and 7 underwent an arterial switch procedure. Twenty-five patients presented with transposition plus ventricular septal defect and left ventricular outflow tract obstruction, 23 of whom underwent a Rastelli procedure. There were one early death (mortality rate 1.9%; 90% confidence limits 0-7%) and three late deaths (mortality rate 5.8%) during a mean follow-up period of 42 months (range 2 to 124). These results show that 1) atrial rerouting is an appropriate surgical procedure for transposition of the great arteries with left ventricular outflow tract obstruction; 2) the arterial switch procedure provides excellent early correction of transposition with ventricular septal defect and is currently the preferred procedure for this lesion; and 3) the Rastelli procedure can be performed with a low early mortality rate and excellent long-term results for transposition with ventricular septal defect and left ventricular outflow tract obstruction.

Adolescent↗
PubMed1989

Prevention of reperfusion injury in the neonatal heart with leukocyte-depleted blood.

Activated leukocytes release oxygen free radicals and cause microvascular occlusion. This experiment tests the hypothesis that reperfusion with leukocyte-depleted blood reduces injury after extended ischemic preservation. An in vitro model consisting of an isolated, working neonatal piglet heart and an adolescent support pig was used. Hearts were arrested with a cold crystalloid cardioplegic solution, excised, and stored in 4 degrees C saline for 12 hours. Two groups were compared. In group 1 piglets (n = 8), reperfused with whole blood, the maximum stroke work index was 0.91 +/- 0.29 x 10(3) erg/gm (mean +/- standard error of the mean). Group 2 piglets (n = 6), reperfused with blood depleted of leukocytes by a polyester filter, had a maximum stroke work index of 11.6 +/- 1.0 x 10(3) erg/gm. This difference was highly significant (p less than 0.0001). Group 1 exhibited severe injury with myofibrillar necrosis, mitochondrial disruption, nuclear chromatin clumping, and moderate interstitial edema. Group 2 had normal ultrastructure on electron microscopic examination. We conclude that reperfusion with leukocyte-depleted blood prevents reperfusion injury and results in excellent myocardial function after long-term heart preservation.

Animals↗
PubMed1989

Definitive repair in patients with pulmonary atresia and intact ventricular septum.

Between 1977 and 1988, 22 patients underwent definitive repair for pulmonary atresia with intact ventricular septum. Fifteen underwent biventricular repair (mean age 24 months). All had mild to moderate right ventricular hypoplasia at the time of definitive repair. Repair consisted of closure of the atrial septal defect with enlargement of the right ventricular cavity and outflow tract with a patch in eight, insertion of a valved homograft in three, and superior vena cava-pulmonary artery connection in four. There was one operative death (7%). Seven patients had severe right ventricular hypoplasia at the time of definitive repair and underwent a Fontan procedure (mean age 46 months). In two a valved connection was made to the right ventricle and in five a right atrial-pulmonary artery nonvalved connection. There were two operative deaths (29%). Three patients had right ventricular-coronary sinusoids: Two of them underwent a Fontan procedure and one a biventricular repair. We conclude that with adequate early palliation a biventricular repair may be successfully performed for patients with mild or moderate right ventricular hypoplasia, and the Fontan procedure may be used for those with severe right ventricular hypoplasia.

Child↗
PubMed1989

Studies on prolonged acute regional ischemia. VI. Myocardial infarction with left ventricular power failure: a medical/surgical emergency requiring urgent revascularization with maximal protection of remote muscle.

Eighty consecutive patients receiving maximum inotropic and intraaortic balloon support underwent emergency coronary artery bypass grafting 3.4 +/- 1 days (mean +/- standard error) after infarction for severe left ventricular power failure (stroke work index less than 25 gm-m, left atrial pressure greater than 20 mm Hg). All underwent induction of cardioplegia with a 37 degrees C glutamate/aspartate blood cardioplegic solution, multidose cold (4 degrees C) replenishment, and warm reperfusate. Viable areas were grafted first to ensure cardioplegic distribution. Left ventricular power failure was reversed in 94% of patients; 75 of 80 patients had discontinuation of inotropic drugs and intraaortic balloon support. The early mortality rate (less than 30 days) was only 7% (3/45) with early operation (less than 18 hours) and rose to 31% (11/35, p less than 0.05) if operation was delayed more than 18 hours. Six of 14 early deaths were due to progression of preoperative organ failure despite reversal of shock. Eighteen of 66 early survivors died of end-stage heart failure (21/80), a 26% late mortality rate. Nonsurvivors (early and late) had a higher incidence of extending versus evolving infarction (33/64 versus 2/16, p less than 0.05), a longer delay from shock to operation (11/45 versus 24/35, p less than 0.05), more preoperative organ failure (9/9 versus 26/71, p less than 0.05), and a greater incidence of previous infarction (22/43 versus 13/37, p greater than 0.05). Thirty of 45 late survivors (67%) remain physically active. We conclude that left ventricular power failure should be considered a medical/surgical emergency that necessitates prompt angiography and can be reversed in selected patients. Postoperative mortality (early and late) is due principally to delay of operation leading to progression of preoperative organ failure or progression of underlying cardiac disease if infarction becomes established.

Emergencies↗
PubMed1988

Percutaneous double-balloon angioplasty of a stenotic modified Fontan aortic homograft conduit.

A 28-year-old woman with pulmonary atresia underwent a modified Fontan procedure that utilized a valved aortic homograft; she developed stenosis of the distal anastomosis between the homograft and the pulmonary artery. Because of the increased risk of reoperation, balloon angioplasty of this stenotic lesion was performed successfully. In the subsequent 11 months she has remained asymptomatic. Balloon angioplasty was a successful alternative to reoperation in this patient.

Adult↗
PubMed1988

Hemodynamic responses to isolated increments in heart rate by atrial pacing after a Fontan procedure.

The physiologic role of the right ventricle has long been a subject of interest to physiologists. The Fontan operation provides a human model for studying the circulation in series devoid of a subpulmonic right ventricle. The hemodynamic response to isotonic exercise in this setting has been established, and differs appreciably from normal. However, the physiologic response to an increase in heart rate (atrial pacing) as an isolated variable has not been examined and compared to atrial pacing in hearts with two concordant subarterial ventricles. Accordingly, we compared the supine bicycle exercise response to rate-equivalent right atrial pacing in nine patients after atriopulmonary anastomoses (the Fontan operation) for single ventricle or tricuspid atresia. Cardiac index increased 77% with exercise (rest 2.6 L/min/m2; exercise 4.6 L/min/m2) but decreased 12% with atrial pacing (rest 2.5 L/min/m2; pacing 2.2 L/min/m2). Pulmonary arterial oxygen saturation declined significantly during exercise (rest 68%; exercise 31%) and during atrial pacing (control 72%; pacing 64%). The mean increment in pulmonary arterial pressure was 1.3 times greater with exercise (rest 14 mm Hg; exercise 20 mm Hg) than with pacing (control 12 mm Hg; pacing 16 mm Hg). Peak systemic arterial systolic pressure increased 14% with exercise but was unchanged by pacing. Systemic and pulmonary vascular resistances fell with exercise but changed insignificantly during atrial pacing. Stroke volume rose slightly with exercise but fell significantly with pacing.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗