Biomedical subjects

P A Ebert

Publications and source records attributed to P A Ebert.

At least 37 records · Page 2Linked to original sources

PubMed1987

Indications and techniques for midline approach to aortic coarctation in infants and children.

A variety of techniques have been described for the repair of aortic coarctation. Most of these use operative exposure through a left thoracotomy. There are, however, instances when a median sternotomy provides a more versatile approach and allows for equally acceptable repair. Twelve patients (age, 2 days to 16 years) with coarctation of the aorta serve to illustrate the value of the technique. All but 3 patients were under 3 years old. Five patients had repair of coarctation combined with repair of other congenital cardiac anomalies (atrial and ventricular septal defects, 2 patients; atrial septal defects, 2 patients; and valvular aortic stenosis, 1 patient). Six patients had complicated recurrences of previously repaired coarctations and 1 patient had a primary coarctation that involved the aortic arch. All repairs were accomplished through a median sternotomy with the use of cardiopulmonary bypass and periods of (1) total circulatory arrest (6 patients); (2) reduced flow (4 patients); or (3) normal flow with multiple sites of arterial inflow (2 patients). All patients did well with no operative mortalities and no sequelae to date (8 weeks to 4 years). Examples of various techniques are provided to demonstrate the flexibility obtainable with this method. Median sternotomy can provide a viable approach to difficult problems involving coarctation of the aorta.

Aortic Coarctation↗

PubMed1987

Infant total anomalous pulmonary venous connection: factors influencing timing of presentation and operative outcome.

The surgical experience in 75 patients with total anomalous pulmonary venous connection (TAPVC) between 1975 and 1986 was reviewed. Most of these patients underwent operation at less than 1 month of age (39 of 75, 52%). Operative approaches used were the standardized left-sided approach for supracardiac and infracardiac TAPVC, reserving transatrial repair for only the intracardiac lesions. Cardiopulmonary bypass was managed by deep hypothermia and circulatory arrest in 16 of 75 (29%) and continuous hypothermic bypass with low flow was used for the remaining 59 of 75 (71%). Operative policy included maintaining patency of existing patent ductus (1 patient) and atrial (4 patients) or ventricular (3 patients) defects to allow additional shunting in cases of severe obstruction. Operative mortality was 9.3% (7 of 75) and late mortality was 6.7% (5 of 75). The determinants of operative deaths were (1) the type of TAPVC (highest rates in types III and IV with 3 of 17 or 19%, and 2 of 8 or 25%, respectively) and (2) associated severe preoperative pulmonary-to-systemic venous obstruction. Determinants of late death were (1) residual pulmonary-to-systemic obstruction (two patients type III and 1 patient type I), and (2) associated intracardiac lesions (two patients type IV with atrioventricular canal). In summary, the timing of corrective surgery and outcome are influenced by the clinical condition of the infant as a direct reflection of the anatomic type and severity of associated lesions.

Age Factors↗

PubMed1987

Surgical options for treating ventricular tachyarrhythmia and sudden death.

From 1981 to 1987, 62 patients with ventricular tachyarrhythmias and associated sudden death required treatment after unsuccessful initial medical therapy (51 patients) and previous surgical therapy (11 patients). Surgical options included direct revascularization (group I, 11 patients), endocardial resection (group II, 7 patients), automatic internal cardiac defibrillators (group III, 18 patients), and these combinations of operations: revascularization and endocardial resection (group IV, 18 patients), revascularization and insertion of automatic internal cardiac defibrillators (group V, 5 patients), and endocardial resection and insertion of cardiac defibrillator (group VI, 3 patients). Five underwent repeat revascularization (4) or endocardial resection (4) with mitral valve replacement (1) or papillary muscle reconstruction (2). The overall operative mortality of 8.1% (5/62) has been acceptable (2.8% or 1/36 for the simple procedures [groups I, II, and III] and 15.4% or 4/26 for the combined procedures [IV, V, and VI]; p less than 0.074). Operative risk factors included recent myocardial infarction (4/5 deaths) and depressed ejection fraction of 23% or less (5/5 deaths). These operative risks were highest in group IV and, thus, the highest mortality was in group IV (4/18 patients or 22%, p less than 0.022). Six late deaths (4 patients in group III) brought the overall survival rate to 82% or 51/62 patients at a mean follow-up of 30 months. Surgical treatment of sudden death ventricular tachyarrhythmias requires a planned, combined operative approach, since initial medical or surgical failures can occur. The optimal surgical approach requires complete revascularization, resection of the localized subendocardial arrhythmogenic focus, and ventricular reconstruction. An automatic defibrillator is a palliative alternative for less favorable surgical anatomy and for patients who are poor operative candidates for these combined or reoperative procedures.

Arrhythmias, Cardiac↗

PubMed1986

Right-sided cardiac transplantation: importance of functional valves.

An original surgical procedure had been developed entailing the implantation of a right-sided heterotrophic cardiac graft in 14 dogs. The benchwork preparation included creation of both atrial and ventricular septal defects which allowed transplantation with the avoidance of extracorporeal circulation and the utilization of all transplanted myocardium and parts. The structure and function of this graft were sequentially evaluated using rapid cine-computed tomograms which permitted assessment of forward graft flow, ventricular wall contraction, and diastolic thickness for both the native and grafted hearts. These parameters were followed during the early (E) (less than 3 days), intermediate (I) (4-21 days), and late (L) (greater than 21 days) postoperative periods. Forward flow (E: 3.0, I: 1.5, L: 2.6) through the transplant was maintained by the competence of the implanted valves despite a progressive decrease in the contraction (E: 3.0, I: 1.3, L: 1.0) and associated decrease in the wall thickness (E: 3.0, I: 2.6, L: 2.4). These findings were consistent with severe cardiac graft rejection without immunosuppression. In summary, long-term structural and functional forward flow of this configurated right-sided transplantation had been maintained by the competent valves on both sides of the graft despite severe rejection without immunosuppression as documented by rapid cine-computed tomograms.

Animals↗

PubMed1986

Intracoronary platelet aggregation: pattern of deposition after ischemia, cardioplegia, and reperfusion.

Platelet deposition in the coronary microvasculature has not been completely defined in the temporal relationship to acute myocardial ischemia, the application of crystalloid cardioplegia, and during reperfusion on heart bypass. Twenty-two canine hearts were serially biopsied for the analysis of radioactively tagged platelets. Eleven hearts underwent an isolated heart support preparation with seven followed by potassium cardioplegic arrest and reperfusion while the remaining 4 were maintained on continuous bypass. All 11 hearts undergoing bypass experienced transient (less than 90 sec) ischemia during bypass preparation and produced platelet aggregation in the myocardium (51.12 +/- 24.0 as compared to nonischemic control group 12.3 +/- 4.7; P = 0.005). Potassium cardioplegia did not completely wash out these platelets to the nonischemic control levels (27.8 +/- 14.9; P = 0.04). With the onset of reperfusion after 1 hr of cardioplegic arrest, platelet radioactivity profoundly increased (133.3 +/- 72.8; P = 0.0101) and remained high throughout the hour of reperfusion (324.7 +/- 269.3; P = 0.0369). In summary, intracoronary platelets are activated after transient ischemic episodes during initiation of heart bypass. These ischemia-activated platelet aggregations persist despite the application of cardioplegia during the arrest period. This deposition, in turn, allowed an ongoing pattern of platelet aggregation during the early and subsequent reperfusion. This pattern of ischemia-activated platelet aggregations probably accounts for the progressive reperfusion injury and support of an antiplatelet treatment for coronary microvasculature protection.

Animals↗

PubMed1986

Infant coarctation: a spectrum in clinical presentation and treatment.

Between 1975 and 1985, 125 infants 2 to 365 days old (majority, 30 days old or less) with coarctation of the aorta underwent surgical repair. Forty-seven patients (38%) had severe congestive heart failure (CHF), metabolic acidosis, and poor systemic perfusion. The predominant operative technique was synthetic patch aortoplasty (100 patients); the remaining 25 had an end-to-end anastomosis. There were no operative deaths. Perioperative complications were minimized with the synthetic patch technique (less than 15%). For patients surviving at least 3 months after repair, the arm-leg systolic blood pressure gradient was relieved in 82% (71/87) of the patients having patch aortoplasty versus 65% (15/23) of the patients with end-to-end anastomosis. Although the rate of reoperation between the two groups was similar (patch, 5 [6%]; end-to-end, 3 [13%], two of the reoperations in the patch group were for preexisting hypoplastic transverse aortic arch. Late deaths (20 patients, 16%) were due to other major associated cardiac anomalies. Patch aneurysms have not occurred. Expedient use of synthetic patch aortoplasty has decreased perioperative complications, relieved coarctation gradients for CHF, increased early survival even in the presence of complex or associated cardiac anomalies, and has an acceptable rate of recurrent coarctation (6 to 13%).

Aortic Coarctation↗

PubMed1986

Prevention of ischemia-induced myocardial platelet deposition by exogenous prostacyclin.

The antithrombotic effects of prostacyclin infusion on myocardial platelet deposition were studied in a canine model during and after global ischemia. Eleven isolated heart preparations were subjected to 1 hour of cardioplegic arrest under moderate hypothermia (27 degrees to 28 degrees C), including a control group (n = 7) and a prostacyclin-treated group (n = 4). The hearts of four other dogs were continuously perfused for 180 minutes. Platelet deposition was measured at 15 minute intervals throughout the 3 hour study. Serial full-thickness myocardial biopsy specimens were analyzed for activity of 111In-labeled platelets with 99mTc-labeled erythrocyte correction for tissue blood content. The pattern of platelet distribution was determined by scintiscans of each heart, taken with a gamma camera at the end of the 60 minute reperfusion period. Substantial myocardial platelet deposition was found in the control hearts after ischemia but not in the prostacyclin-treated group (p less than 0.05). Furthermore, prostacyclin infusion had a significant disaggregatory effect on intracoronary platelet deposits when the precardioplegic and postcardioplegic biopsy specimens were analyzed (p less than 0.05). Three hours of continuous perfusion did not increase tissue 111In-labeled platelet activity. Ex vivo images showed platelet deposition to be a diffuse patchy process with significantly more 111In activity in the endocardium than in the epicardium after global ischemia (p less than 0.05). These data show the potent antithrombotic properties of prostacyclin in preventing and disaggregating ischemia-induced intracoronary platelet deposition during and after cardioplegic arrest.

Animals↗

PubMed1986

Aspirin anticoagulation in children with mechanical aortic valves.

The optimal method of anticoagulation in children with mechanical heart valves is controversial. Between 1975 and 1986, aspirin or aspirin with dipyridamole has been used for anticoagulation in children receiving a mechanical aortic valve at the University of California, San Francisco. Fifty-one patients (ages 1 to 23 years, mean 12.9 years) were treated with aspirin (n = 45) or aspirin with dipyridamole (n = 6) and observed a mean of 36.5 months (range 3 to 100 months). There were four late deaths: two from endocarditis and two from other medical problems, but none related to thrombosis or embolus. Follow-up was accomplished by direct contact with the patient, parent, or referring physician. Two patients (3.9%) were lost to late follow-up. One minor neurologic event occurred perioperatively and resolved spontaneously. There were no postoperative thromboembolic events. Eleven asymptomatic children were recently studied by magnetic resonance imaging or computed axial tomography of the brain and had no evidence of prior silent cerebral thromboembolic defects. There were four patients (5.9%) who had minor hemorrhagic complications: Three patients had nosebleeds and one patient had an upper gastrointestinal hemorrhage. Five patients were changed to warfarin anticoagulation: the patient with upper gastrointestinal hemorrhage and four older patients because of physician preference, all after uncomplicated aspirin therapy. There were no mechanical valve failures, although one patient required reoperation 9 months later for perivalvular leak. All children have remained in normal sinus or paced rhythm during follow-up. These results show that children with mechanical aortic valves in normal sinus rhythm can be safely treated with aspirin (or aspirin with dipyridamole) with little risk of thromboembolic events, valve thrombosis, or valve failure. Hemorrhagic complications resulting from aspirin are minor and easily treated.

Adolescent↗

PubMed1985

Does prostacyclin (PGI2) cardioplegic infusion improve myocardial protection after ischemic arrest?

To determine whether prostacyclin (PGI2) plays a beneficial role in the blood-perfused heart undergoing global ischemia, 20 isolated canine hearts were studied after sustaining one hour of cardioplegic arrest under moderate hypothermia (27 degrees to 28 degrees C). Left ventricular function (peak systolic pressure, rate of rise of left ventricular pressure [dP/dt], and compliance change in left ventricular volume), myocardial edema, coronary blood flow, and oxygen content were measured during the preischemic period and at 15 and 30 minutes during reperfusion. Results showed an improved hemodynamic recovery (peak systolic pressure, p = 0.018 at 30 minutes; dP/dt, p = 0.020 at 15 minutes) in the group of hearts treated with PGI2 infusion compared with controls. There was no difference in ventricular compliance or myocardial edema between the two groups. This benefit was attributed to a significant increase in myocardial blood flow (p = 0.028 at 15 minutes) and oxygen delivery (p = 0.021 at 15 minutes) during the reperfusion period with PGI2. These data suggest a potential clinical role for PGI2 when applied to the globally ischemic heart in the improvement of myocardial resuscitation during the early reperfusion period.

Animals↗

PubMed1985

Changes in the respiratory gas tensions of a pneumonectomy space and their application to the diagnosis of bronchopleural fistula.

The oxygen (pO2) and carbon dioxide (pCO2) gas tensions of a pneumonectomy space were studied in an animal model. The 2 gases were measured in a standard blood gas analyser. The space gas pO2 and pCO2 equilibrated to a steady state within 48 hours of thoracotomy (pO2 mean 53.9 +/- 9.3 SD torr; pCO2 mean 44.8 +/- 9.9 SD torr). In the presence of a bronchopleural fistula (BPF), the pO2 rose significantly (mean pO2 118.4 +/- 13.2 SD torr; p less than 0.001). The space pCO2 usually fell, but the response was inconsistent (mean pCO2 33.6 +/- 16.4 SD; p = NS). A further rise in space pO2 could sometimes be induced by allowing the animals to breathe 100% oxygen by face mask. Data from 4 clinical cases of BPF support the concept that measurement f the space gas pO2 could be used as a bedside test for BPF.

Animals↗

PubMed1984

Synthetic patch aortoplasty. A simplified approach for coarctation in repairs during early infancy and thereafter.

Synthetic patch aortoplasty is an expedient, safe technique for coarctation repairs during early infancy and thereafter for reoperation since it affords both an immediate hemodynamic result and potential for late growth while avoiding sacrifice of a major arch vessel. The surgical advantages include minimization of the total cross-clamp time (10 minutes in infants and 12 minutes in older patients) and elimination of the need to sacrifice collateral vessels and the need for extensive dissection for proximal and distal control. Hence, this technique has minimized the associated severe complications of coarctation repair, even in emergency cases. In our study, there were no operative deaths, spinal cord injuries or recoarctation, and intraoperative cardiac arrest occurred in only 3 percent of the patients.

Abnormalities, Multiple↗

PubMed1984

The effect of paralysis on oxygen consumption in normoxic children after cardiac surgery.

To determine whether paralysis reduces oxygen consumption (V02) after cardiac surgery in infants, the authors measured V02 before and after paralysis in 17 sedated infants who were ventilated mechanically after cardiac surgery. Oxygen consumption was determined as being the difference between oxygen content of inspired and expired gases. The absence or presence of "movement" (breathing or repeated movement of the extremities) before paralysis was noted. For eight infants who did not "move" before paralysis, VO2 was similar before (9.1 +/- 1.2 ml . kg-1 . min-1, mean +/- SD) and after (9.0 +/- 1.5 ml . kg-1 . min-1) paralysis (P = 0.81). However, for nine infants who did "move" before paralysis, VO2 decreased from 9.2 +/- 1.4 ml . kg-1 . min-1 before paralysis to 8.0 +/- 1.4 ml . kg-1 . min-1 after paralysis (P less than 0.05). One infant in each group had an increase in VO2 greater than 10% of the baseline value (i.e., 12% and 14%). In conclusion, if breathing or repeated movement is present before paralysis, paralysis decreases VO2 by 13% in sedated infants after cardiac surgery. If repeated or regular movement is not present before paralysis, paralysis does not decrease VO2. These data suggest that in normoxic patients, muscle paralysis does not significantly alter V02 and therefore should not be used for this purpose.

Anesthesia↗

PubMed1984

Surgical treatment of truncus arteriosus in the first 6 months of life.

One hundred six infants were seen at the University of California Medical Center between 1974 and 1981 with the diagnosis of truncus arteriosus. One hundred of these underwent physiologic correction prior to 6 months of age. Six infants died prior to operation while undergoing intense medical therapy to improve their basic condition. There were 11 operative deaths with a mortality rate of 11%. Of the 86 long-term survivors, 55 have returned for conduit change because of either body growth or pseudointima proliferation of the conduit. There had been no mortalities at the time of conduit change, and 29 of these were repaired using a straight tube between the ventricle and pulmonary trunk, while 26 had valve conduits placed. Physiologic correction in the first 6 months of life has been accomplished with a low mortality rate and apparent good long-term results with none of the survivors having evidence of elevated pulmonary vascular resistance.

Blood Vessel Prosthesis↗

PubMed1984

The total repair of interrupted arch complex in infants: the anterior approach.

Results of repair of the interrupted arch complex have remained poor despite advances in operative technique. Palliative prosthetic grafts to form a transverse arch through the lateral approach have been advocated, but a need for both subsequent closure of the ventricular septal defect and replacement of the prosthetic conduit makes this approach undesirable. The total experience with this lesion at the University of California San Francisco (29 patients) is presented. Since January 1982, 10 patients, eight with type B and two with type A interrupted arch, underwent total repair. Ages ranged from 3 to 150 days (median 11 days). An anterior approach to total repair with single atrial-to-ascending aortic and transductal descending aortic bypass was used. Deep hypothermia to less than 18 degrees C was used, and during total circulatory arrest the cannula was removed from the descending aorta and direct anastomosis of the descending and ascending aorta was performed. Total circulatory arrest time was a mean of 12 min. During rewarming of the infant, the ventricular septal defect was closed. Mean pump time was 52 min. Operative mortality was 20% (two of 10 patients) at 17 and 32 days after surgery. Our results demonstrate that the anterior approach to total repair of interrupted arch complex in early infancy can be achieved with a lower mortality than palliation followed by subsequent closure of ventricular septal defect and also obviates the need for prosthetic replacement of the transverse arch. The anterior approach is the method of choice for repair of interrupted arch complex.

Aorta, Thoracic↗

PubMed1984

Staged partitioning of single ventricle.

Five patients between the ages of 3 and 10 months underwent a two-stage septation for common ventricle. The first stage involved the placement of a small patch in the apex and a second patch between the atrioventricular and semilunar valves. A center section was left open, as if there were ventricular septal defect. A pulmonary band was placed at this time if one had not been previously placed. The second stage of the repair, consisting of closure of the ventricular septal defect, was performed 6 to 18 months after the first procedure. All five patients have survived and have been without rhythm disturbance. One patient subsequently developed pulmonary stenosis, and a right ventricle-pulmonary artery conduit has been placed. The first stage procedure seems to allow the apical and base patches to stiffen and heal to the endocardium, with fewer sutures required because the central area is open and no pressure differential exists across the patch.

Heart Septal Defects, Ventricular↗

PubMed1984

Successful aortic valvotomy for severe congenital valvular aortic stenosis in the newborn infant.

The preoperative evaluation, surgical course, and early follow-up results of 11 newborn infants less than 30 days of age who underwent aortic valvotomy for severe valvular aortic stenosis between 1976 and 1983 were reviewed to determine our current surgical mortality and the early prognosis of these neonates. Ten of the 11 patients had severe congestive heart failure and dyspnea. Preoperative cardiac catheterization and angiography detected features characteristic of congenital aortic valvular stenosis in newborn infants. Emergency aortic valvotomy was performed in all during cardiopulmonary bypass, for which a cold (4 degrees C) blood prime and moderate systemic hypothermia were used. An effort was made to achieve maximal relief of the stenosis without causing aortic insufficiency. Mean cardiopulmonary bypass time was 21 minutes and mean cross-clamp time was 6.4 minutes. There was a single operative death, and there have been no late deaths during a mean follow-up period of 2.2 years. All patients are currently free of heart failure. Four patients underwent postoperative cardiac catheterization for clinical suspicion of severe residual stenosis. However, three had only mild or moderate residual stenosis. The fourth had a large gradient, 70 mm Hg, and has since undergone successful repeat valvotomy. These results indicate that neonates with severe valvular aortic stenosis can undergo valvotomy safely and have a favorable early prognosis. The factors responsible for the low mortality appear to include prompt recognition and diagnosis followed by emergency operation, use of a 4 degree C cold pump prime, brief cross-clamp times, and conservative valvotomy to avoid the development of significant aortic insufficiency.

Aortic Valve↗

PubMed1983

Pulmonary valve replacement for regurgitation after repair of tetralogy of Fallot.

In general, it has been thought that pulmonary valve insufficiency is well tolerated when the valve is excised or when the pulmonary annulus has been widened with an outflow patch during repair of tetralogy of Fallot. However, when pulmonary regurgitation is massive or when it is combined with other causes of right ventricular failure, progressive right ventricular dilation may occur in some patients. Pulmonary valve replacement has not been commonly used in the past. From January, 1980, to August, 1982, 12 patients, 11 months to 17 years old, had pulmonary regurgitation treated by insertion of a valve in the pulmonary position 4 1/2 months to 11 years after initial repair of tetralogy of Fallot. All patients had progressive right ventricular failure not responsive to medical management. There were no major outflow tract obstructions, residual ventricular septal defects, or persistent aortopulmonary shunts. All 12 patients underwent patch reconstruction of the right ventricular outflow tract that allowed placement of a larger valve. There have been no operative or late deaths, and each patient has had improvement in functional status. One patient required tricuspid valve replacement 1 1/2 years after pulmonary valve replacement to achieve sustained relief of symptoms. Only 1 other patient required subsequent operation; this was for pacemaker lead changes. These early results suggest that in patients with right ventricular failure, attention should be directed to pulmonary regurgitation since this is a component of failure that is reversible; pulmonary valve replacement carries a low risk, and it can relieve symptoms and prevent further deterioration of right ventricular function.

Adolescent↗

PubMed1983

Surgery for cyanotic heart disease in the first year of life.

Data are reviewed on 248 patients less than 1 year old who presented with a diagnosis of cyanotic heart disease between January 1976 and January 1982. No infant had had prior surgical treatment. The patients were classified according to diagnosis: tetralogy of Fallot, transposition of the great arteries, pulmonary atresia and anomalies of the tricuspid atresia or single ventricle type. Other remote forms of cyanotic heart disease were excluded from the analysis. Management of these patient groups is discussed in relation to their potential for corrective surgery early in infancy or later. The proper selection of palliative procedures that will permit bilateral growth and development of pulmonary arteries and equal distribution of pulmonary blood flow is emphasized. Morbidity and mortality in each patient group are discussed.

Heart Defects, Congenital↗