Biomedical subjects

J E Mayer

Publications and source records attributed to J E Mayer.

At least 73 records · Page 4Linked to original sources

PubMed1998

Use of an ultrasonic scalpel as an alternative to electrocautery in patients with pacemakers.

We report the safe and effective use of an ultrasonically activated scalpel as an alternative to unipolar electrocautery during surgical procedures in 4 patients with pacemakers. This scalpel provided adequate hemostasis without the adverse consequences of electromagnetic interference. As the scalpel was able to easily cut through the silicone connector sleeve of one generator, it is not recommended for routine generator replacement because it may damage existing pacing leads. However, its use during nonpacemaker operations in patients with pacemakers should be considered.

Adult↗

PubMed1998

Validation of relative value scale for congenital heart operations.

BACKGROUND: To determine the validity of the newly assigned work relative value unit (RVU) scale for surgical procedures for congenital heart disease, we measured its relationship to length of hospital stay, total hospital charges, and mortality. METHODS: We identified cases by the presence of ICD-9-CM codes in nine statewide, administrative hospital discharge abstract databases for 1992. Computer algorithms were generated to assign RVUs to individual cases. Spearman correlation coefficients between work and practice expense RVUs and median length of hospital stay, total hospital charges, and in-hospital mortality were determined, as well as parameter estimates from linear and logistic regression. RESULTS: Using data from 5,192 cases involving 34 surgical procedures for congenital heart disease, higher work RVUs were associated with longer lengths of hospital stay (rs = 0.72, p < 0.0001), higher total hospital charges (rs = 0.81, p < 0.0001), and higher in-hospital mortality (rs = 0.45, p = 0.01). A 5-point increase in the relative value scale was associated with an increase in the length of stay by a multiplicative factor of 1.3 (p < 0.0001); total hospital charges by 1.5 (p < 0.0001); and the odds of in-hospital death by 1.9 (p < 0.0001). Findings were similar for practice expense RVUs, as work and practice expense RVUs were highly correlated (rs = 0.93, p < 0.0001). CONCLUSIONS: The group of work RVUs for surgical procedures for congenital heart defects are reasonable relative measures, on average, of physician work for these procedures, thus supporting the use of this scale to determine physician reimbursement. Practice expense RVUs may not be an independent measure for these procedures.

Cardiac Surgical Procedures↗

PubMed1998

Use of rapid-deployment extracorporeal membrane oxygenation for the resuscitation of pediatric patients with heart disease after cardiac arrest.

INTRODUCTION: We have recently used extracorporeal membrane oxygenation as a means of rapidly resuscitating pediatric patients with heart disease after cardiopulmonary arrest, in whom conventional resuscitation measures have failed. METHODS: We developed a fully portable extracorporeal membrane oxygenation circuit that is maintained vacuum and carbon dioxide-primed at all times. When needed, the circuit is crystalloid-primed and can be ready for use within 15 minutes. Since February 1996, we have used this rapid-deployment circuit to resuscitate 11 pediatric patients in full cardiopulmonary arrest. RESULTS: The median age of the 11 patients was 120 days (2 days to 4.6 years). Nine patients had a cardiac arrest after cardiac surgery. One patient had a cardiac arrest during cardiac catheterization and one patient had a cardiac arrest before cardiac surgery. Median duration of cardiopulmonary resuscitation was 55 minutes (range 20 to 103 minutes), with no difference in the duration of cardiopulmonary resuscitation between survivors and nonsurvivors. Ten of 11 patients (91%) were weaned from extracorporeal membrane oxygenation and seven (64%) survived to hospital discharge. Six patients are long-term survivors, five of whom are in New York Heart Association class I; one survivor is in class II. Seven patients resuscitated with extracorporeal membrane oxygenation before the use of this rapid-deployment circuit had a median duration of cardiopulmonary resuscitation of 90 minutes, with two (28.6%) survivors. CONCLUSIONS: The use of rapid-deployment extracorporeal membrane oxygenation results in shorter resuscitation times and improved survival in pediatric patients with heart disease after cardiopulmonary arrest.

Cardiac Surgical Procedures↗

PubMed1998

Creation of viable pulmonary artery autografts through tissue engineering.

BACKGROUND: "Repair" of many congenital cardiac defects requires the use of conduits to establish right ventricle to pulmonary artery continuity. At present, available homografts or prosthetic conduits lack growth potential and can become obstructed by tissue ingrowth or calcification leading to the need for multiple conduit replacements. Tissue engineering is an approach by which cells are grown in vitro onto biodegradable polymers to construct "tissues" for implantation. A tissue engineering approach has recently been used to construct living cardiac valve leaflets from autologous cells in our laboratory. This study assesses the feasibility of a tissue engineering approach to constructing tissue-engineered "living" pulmonary artery conduits. MATERIALS AND METHODS: Ovine artery (group A, n = 4) or vein (group V, n = 3) segments were harvested, separated into individual cells, expanded in tissue culture, and seeded onto synthetic biodegradable (polyglactin/polyglycolic acid) tubular scaffolds (20 mm long x 15 mm diameter). After 7 days of in vitro culture, the autologous cell/polymer vascular constructs were used to replace a 2 cm segment of pulmonary artery in lambs (age 68.4 +/- 15.5 days, weight 18.7 +/- 2.0 kg). One other control animal received an acellular polymer tube sealed with fibrin glue without autologous cells. Animals were sacrificed at intervals of 11 to 24 weeks (mean follow-up 130.3 +/- 30.8 days, mean weight 38.9 +/- 13.0 kg) after echocardiographic and angiographic studies. Explanted tissue-engineered conduits were assayed for collagen (4-hydroxyproline) and calcium content, and a tissue deoxyribonucleic acid assay (bis-benzimide dye) was used to estimate number of cell nuclei as an index of tissue maturity. RESULTS: The acellular control graft developed progressive obstruction and thrombosis. All seven tissue-engineered grafts were patent and demonstrated a nonaneurysmal increase in diameter (group A = 18.3 +/- 1.3 mm = 95.3% of native pulmonary artery; group V = 17.1 +/- 1.2 mm = 86.8% of native pulmonary artery). Histologically, none of the biodegradable polymer scaffold remained in any tissue-engineered graft by 11 weeks. Collagen content in tissue-engineered grafts was 73.9% +/- 8.0% of adjacent native pulmonary artery. Histologically, elastic fibers were present in the media layer of tissue-engineered vessel wall and endothelial specific factor VIII was identified on the luminal surface. Deoxyribonucleic acid assay showed a progressive decrease in numbers of cell nuclei over 11 and 24 weeks, suggesting an ongoing tissue remodeling. Calcium content of tissue-engineered grafts was elevated (group A = 7.95 +/- 5.09; group V = 13.2 +/- 5.48; native pulmonary artery = 1.2 +/- 0.8 mg/gm dry weight), but no macroscopic calcification was found. CONCLUSIONS: Living vascular grafts engineered from autologous cells and biodegradable polymers functioned well in the pulmonary circulation as a pulmonary artery replacement. They demonstrated an increase in diameter suggesting growth and development of endothelial lining and extracellular matrix, including collagen and elastic fibers. This tissue-engineering approach may ultimately allow the development of viable autologous vascular grafts for clinical use.

Animals↗

PubMed1998

Effects of adenosine infusion with or without leukocyte depletion on recovery after hypothermic ischemia in neonatal lamb hearts.

OBJECTIVE: Leukocytes have been shown to have an important role in ischemia/reperfusion injury. Adenosine also reduced this ischemia/reperfusion injury. There is an interaction between adenosine and leukocyte via receptor mediated function. To determine whether beneficial effects of adenosine on reperfusion injury is mediated by changes in leukocyte function, we studied the effects of adenosine with and without leukocyte depletion during reperfusion on the functional recovery of the neonatal myocardium after cold cardioplegic arrest. MATERIALS AND METHODS: We infused adenosine (350 micromol/l) during the first 20 min of reperfusion for adenosine treated group and adenosine-leukocyte treated group. The other two groups were perfused with leukocyte treated blood or untreated blood. All the groups were subjected to 2 h of cold cardioplegic ischemia (n = 8 in each group). At 30 min of reperfusion, LV function was measured. Coronary blood flow and oxygen consumption (MVO2) were also measured to evaluate the metabolic recovery. RESULTS: Adenosine treated, adenosine-leukocyte treated, and leukocyte treated groups showed better functional recovery than the control group (maximum developed pressure: control = 74.6 +/- 5.6%, adenosine treated = 97.6 +/- 9.5%, adenosine-leukocyte treated = 98.5 +/- 5.6%, leukocyte treated = 82.5 +/- 6.0%. P < 0.05). Both adenosine treated and adenosine-leukocyte treated groups showed better recovery than leukocyte treated group (P < 0.05). Coronary blood flow was higher in adenosine-leukocyte treated group compared to other groups (P < 0.05). MVO2/beat was higher in adenosine treated, adenosine-leukocyte treated, and leukocyte treated groups than control group (P < 0.05). CONCLUSION: Adenosine, with or without leukocyte depletion, had similar beneficial effect on recovery of systolic and diastolic functions, which involved other mechanisms in addition to the leukocyte inhibitory effect.

Adenosine↗

PubMed1998

Long-term performance of bipolar epicardial atrial pacing using an active fixation bipolar endocardial lead.

Bipolar epicardial leads are not yet widely available for atrial use. Since September 1986, we have used a bipolar active fixation endocardial lead (Cardiac Pacemakers model number's 4266, 4268, and 4269) as a bipolar epicardial atrial lead by attaching the corkscrew tip to the atrial surface and imbricating atrial tissue around the more proximal electrode. A total of 77 bipolar epicardial atrial leads have been implanted using this approach in 72 patients with congenital heart disease (ages 3 months to 38.7 years; mean 8.9 +/- 8.8 years). Indications for atrial pacing included AV block (n = 46), sinus node dysfunction (n = 17), and antitachycardial pacing (n = 9). Indications for epicardial pacing included the presence of an intracardiac right to left shunt (n = 33), concomitant cardiac surgery (n = 26), surgeon preference (n = 7), and lack of transvenous access to the atrial endocardium (n = 6). Follow-up (median 23 months; mean 28.0 +/- 23.1 months; range 1-78 months) data beyond 1 month postimplantation were available for 44 leads. Atrial sensing was > or = 2.0 mV for 26 leads (59%) with sensing possible at > or = 0.75 mV for 42 leads (95%). Threshold data were available at 5 V for 37 leads and at 2.5 V for 36 leads with mean pulse width thresholds measuring 0.21 +/- 0.33 ms and 0.34 +/- 0.34 ms, respectively. Two leads failed (high capture thresholds at 5 days [n = 1], lead fracture at 42 months [n = 1]; one of which was replaced. Four additional leads were replaced electively (marginal thresholds [n = 1], intermittent phrenic nerve stimulation [n = 1], damaged during subsequent surgery [n = 1], clinically irrelevant insulation break [n = 1]) concomitant with additional cardiac surgery. Until a commercially available lead is developed and released, improvisation with a bipolar active fixation endocardial lead as a bipolar epicardial atrial lead is a reasonable approach to providing bipolar atrial sensing and pacing in patients for whom endocardial pacing is contraindicated.

Adolescent↗

PubMed1997

Tissue-engineered heart valve leaflets: does cell origin affect outcome?

BACKGROUND: We previously reported the successful creation of tissue-engineered valve leaflet constructs and the implantation of these autologous tissue leaflets in the pulmonary valve position in a lamb model. The optimal cell origin for creating these valve leaflets remains unclear. This study was designed to compare dermal with arterial wall myofibroblasts as the cells of origin for the leaflet constructs. METHODS AND RESULTS: Mixed cell populations of endothelial cells and fibroblasts were isolated from ovine femoral arteries or subdermis and then expanded in vitro. A synthetic biodegradable polymer scaffold was then seeded with the cultured cells. The tissue scaffold was composed of a polyglactin woven mesh sandwiched between two nonwoven polyglycolic acid mesh sheets, which measured 3x3 cm in size and 3.2 mm in thickness. The cell-seeded polymer construct was implanted to replace one pulmonary valve leaflet in the same juvenile animal from which the cells had originally been obtained. Using cardiopulmonary bypass, the right posterior leaflet of the pulmonary valve was completely resected and replaced with an autologous engineered valve leaflet. In group D (n=5), the cells were obtained from subdermis, and in group A (n=4), they were obtained from the arterial wall. Eight to 10 weeks after leaflet implantation, the animals were killed, and the implanted valve leaflets were examined histologically, biochemically, and biomechanically. The dimensions of each tissue-engineered leaflet (TEL) were compared with those of the two remaining native valve leaflets to obtain a growth index. A 4-hydroxyproline assay was performed to evaluate collagen content. Leaflet tensile strength was evaluated in vitro by using a Vitrodyne V-1000 mechanical tester. Factor VIII and elastin stains were performed to histologically assess the presence of endothelial cells and elastin, respectively. In all animals, the TEL persisted in the pulmonary valve position after 8 to 10 weeks, and all polyglycolic acid polymer had been degraded. Group A leaflets had a higher growth index (0.86+/-0.11) than group D (0.41+/-0.08) (P<.05). Macroscopically, the group D leaflets appeared thicker and contracted. Histologically, elastic fibers were more abundant in group A than in group D. Total collagen content and biomechanical testing showed no differences between groups. Leaflets from both groups had positive staining for factor VIII on the surface, confirming growth of endothelial cells to cover the TEL. CONCLUSIONS: Autologous TEL derived from vascular fibroblasts seem to develop functionally and morphologically like the native valve leaflets in the pulmonary circulation. Use of arterial myofibroblasts for the creation of TEL seems preferable to dermal fibroblasts with current tissue culture conditions.

Animals↗

PubMed1997

Relationship of blood flow effects of adenosine during reperfusion to recovery of ventricular function after hypothermic ischemia in neonatal lambs.

BACKGROUND: Previous experiments have shown that infusion of either adenosine (ADO) or an adenosine receptor agonist during reperfusion after hypothermic ischemia improved the recovery of ventricular function in neonatal lamb hearts. Adenosine has multiple actions that might be beneficial during postischemic reperfusion, and the A2 effects include both coronary vasodilator and leukocyte inhibitory effects. In the current experiment we investigated the relationship between the coronary blood flow (CBF) effects of A2 stimulation and the recovery of postischemic ventricular function. METHODS AND RESULTS: Two hours of 10 degrees C cardioplegic ischemia was induced in 40 isolated, blood-perfused, neonatal lamb hearts (n=8 in each group). Group I had ischemia followed by unmodified reperfusion for 90 minutes. During the first 20 minutes of reperfusion, Group II received 350 micromol/L ADO, Group III received ADO and 100 nmol/L DPCPX (A1 antagonist) to achieve an A2 effect, Group IV received 0.25 micromol/L CPCA (A2 agonist), and Group V received ADO and DPCPX but CBF was limited to that of Group I levels. At 30 and 90 minutes of reperfusion, LV maximum developed pressure (DP), dP/dt, CBF, and oxygen consumption (MVO2) were measured. At 30 minutes of reperfusion Groups II, III, and IV showed better functional recovery than Group I or Group V (DP: G-I=75.7+/-7.3%, G-II=97.6+/-9.5%, G-III=88.1+/-4.8%, G-IV=86.7+/-9.0%, G-V=75.5+/-6.9%, P<.05; dP/dt: G-I=69.1+/-9.6%, G-II=94.2+/-10.7%, G-III=95.7+/-13.1%, G-IV=80.1+/-11.1%, G-V=75.2+/-8.2%, P<.05). Coronary blood flow was higher in Groups II, III, and IV compared with Group I or V (G-1=129+/-32%, G-II=183+/-36%, G-III=266+/-72%, G-IV=259+/-70%, G-V=132+/-5%, P<.05). MVO2/beat was higher in Group II than in Groups I and IV (G-I=98.3+/-21.3%, G-II=135.5+/-28.0%, G-III=126.2+/-21.9%, G-IV=102.5+/-16.7%, G-V=107.5+/-29.3%, P<.05). At 90 minutes of reperfusion, Groups II, III, and IV, as well as V, showed better recovery of DP and dP/dt compared with Group I (DP: G-I=50.6+/-11.4%, G-II=63.0+/-8.7%, G-III=69.0+/-10.8%, G-IV=72.5+/-12.7%, G-V=66.2+/-10.0%, P<.05; dP/dt: G-I=38.9+/-7.1%, G-II=53.5 +/-3.8%, G-III=61.5+/-10.8%, G-IV=59.8+/-16.3%, G-V=58.2+/-9.8%, P<.05) although only in Groups III and IV was CBF higher than in Group I (G-1=116+/-54%, G-II=116+/-27%, G-III=210+/-67%, G-IV=239+/-85%, G-V=130+/-8%, P<.05). CONCLUSIONS: Reperfusion under conditions of A2 stimulation by ADO, by an A2 agonist, or by ADO plus A1 blockade was associated with improved recovery of LV function. The early A2 effect seems to be related to coronary vasodilation because reduced CBF (equal to Group I) in Group V reduced early recovery of LV function. However, there seems to be a second effect observed at 90 minutes that is not related to CBF inasmuch as Groups II and V had CBF equal to Group I but had significantly higher DP and dP/dt. These findings suggest that mechanisms in addition to vasodilation are involved in the beneficial effects of A2 stimulation during postischemic reperfusion.

Adenosine↗

PubMed1997

Soluble adhesion molecules in infants and children undergoing cardiopulmonary bypass.

BACKGROUND: The vascular injury and tissue damage after cardiopulmonary bypass (CPB) involves leukocyte-endothelial interactions mediated by cell adhesion molecules. This study was designed to determine the time course of soluble adhesion molecule levels after CPB in infants and children and to determine whether these levels correlated with preoperative variables, intraoperative bypass management, or postoperative course. METHODS AND RESULTS: In 56 patients undergoing CPB (median age 1.0 year, range 2 days to 19 years), plasma concentrations of soluble E-, P-, and L-selection, soluble ICAM-1, and soluble VCAM-1 were measured using sandwich enzyme-linked immunosorbent assays at the following times: at induction of anesthesia, after 15 minutes of CPB, at the end of CPB, and 1, 6, 18, and 42 hours after CPB. Preoperative, intraoperative, and postoperative data were prospectively recorded. All soluble adhesion molecule levels fell markedly at the initiation of CPB as a result of a combination of dilution and bypass circuit uptake. The time course of soluble selectins (P, E, and L), normalized to end of bypass levels, all rose significantly (P<.001) in the initial 6 hours after CPB and then returned to end bypass levels at 42 hours. Soluble ICAM-1 and VCAM rose 63% and 89% in the first 6 hours and remained elevated throughout the 42 hours. Peak soluble P-selectin levels were associated with total support time (P=.04) and preoperative cyanosis (P=.003). Soluble L-selectin levels were inversely associated with longer total support time (P=.002), longer circulatory arrest time (P=.004), longer length of intubation (P=.0009), preoperative cyanosis (P=.002), and younger age at surgery (P=.01). CONCLUSIONS: Soluble adhesion molecules have a characteristic time course in infants and children undergoing CPB. The soluble adhesion molecule levels after CPB change most significantly in patients with the highest potential for vascular injury: younger, cyanotic patients with longer pump times and longer postoperative courses. These data may be useful in the assessment of new therapies.

Adolescent↗

PubMed1997

An institutional experience with second- and third-stage palliative procedures for hypoplastic left heart syndrome: the impact of the bidirectional cavopulmonary shunt.

OBJECTIVES: The aim of this study was to perform a retrospective analysis of an institutional experience with a consecutive series of patients with post-stage I palliation for hypoplastic left heart syndrome (HLHS). BACKGROUND: In a recent review of 212 consecutive patients who underwent stage I operations for HLHS at our institution between 1983 and 1993, we identified risk factors related to stage I mortality. We sought to examine the outcome for these patients at subsequent palliative procedures. METHODS: All patients who underwent stage I reconstruction between January 1983 and June 1993 and also underwent subsequent palliation at our institution were included. Seventy patients underwent palliative procedures and two underwent heart transplantation. Patient-specific factors and features of the stage II operation were analyzed for impact on stage II mortality and actuarial survival. RESULTS: The only independent risk factor for stage II mortality was the performance of a nonfenestrated Fontan operation (p < 0.001). There were nine in-hospital deaths (69%) in the 13 patients undergoing the nonfenestrated Fontan procedure at stage II. Fifty patients underwent intermediate superior vena cava to pulmonary artery anastomosis at stage II, with 4 (8%) early deaths. Pulmonary artery augmentation was performed in 19 patients (38%) at stage II, without increased operative risk. Hypoplastic left heart syndrome anatomic subtype did not influence stage II mortality. The modified fenestrated Fontan procedure has been performed as a third stage in 32 patients whose median age was 28.7 months, with one early death at a median follow-up of 24.5 months. CONCLUSIONS: A second-stage bidirectional cavopulmonary anastomosis for HLHS reduces second-stage mortality and improves intermediate survival. The modified fenestrated Fontan operation may then be performed as a final palliative stage with low operative risk.

Child, Preschool↗

PubMed1997

Perioperative effects of alpha-stat versus pH-stat strategies for deep hypothermic cardiopulmonary bypass in infants.

OBJECTIVES: In a randomized, single-center trial, we compared perioperative outcomes in infants undergoing cardiac operations after use of the alpha-stat versus pH-stat strategy during deep hypothermic cardiopulmonary bypass. METHODS: Admission criteria included reparative cardiac surgery, age less than 9 months, birth weight 2.25 kg or more, and absence of associated congenital or acquired extracardiac disorders. RESULTS: Among the 182 infants in the study, diagnoses included D-transposition of the great arteries (n = 92), tetralogy of Fallot (n = 50), tetralogy of Fallot with pulmonary atresia (n = 6), ventricular septal defect (n = 20), truncus arteriosus (n = 8), complete atrioventricular canal (n = 4), and total anomalous pulmonary venous return (n = 2). Ninety patients were assigned to alpha-stat and 92 to pH-stat strategy. Early death occurred in four infants (2%), all in the alpha-stat group (p = 0.058). Postoperative electroencephalographic seizures occurred in five of 57 patients (9%) assigned to alpha-stat and one of 59 patients (2%) assigned to pH-stat strategy (p = 0.11). Clinical seizures occurred in four infants in the alpha-stat group (4%) and two infants in the pH-stat group (2%) (p = 0.44). First electroencephalographic activity returned sooner among infants randomized to pH-stat strategy (p = 0.03). Within the homogeneous D-transposition subgroup, those assigned to pH-stat tended to have a higher cardiac index despite a lower requirement for inotropic agents; less frequent postoperative acidosis (p = 0.02) and hypotension (p = 0.05); and shorter duration of mechanical ventilation (p = 0.01) and intensive care unit stay (p = 0.01). CONCLUSIONS: Use of the pH-stat strategy in infants undergoing deep hypothermic cardiopulmonary bypass was associated with lower postoperative morbidity, shorter recovery time to first electroencephalographic activity, and, in patients with D-transposition, shorter duration of intubation and intensive care unit stay. These data challenge the notion that alpha-stat management is a superior strategy for organ protection during reparative operations in infants using deep hypothermic cardiopulmonary bypass.

Acid-Base Equilibrium↗

PubMed1997

Fontan operation in five hundred consecutive patients: factors influencing early and late outcome.

OBJECTIVES: The purpose of this study was to review a large, evolving, single-center experience with the Fontan operation and to determine risk factors influencing early and late outcome. METHODS: The first 500 patients undergoing modifications of the Fontan operation at our institution were identified. Perioperative variables were recorded and a cross-sectional review of survivors was undertaken. RESULTS: The incidence of early failure decreased from 27.1% in the first quartile of the experience to 7.5% in the last quartile. In a multivariate model, the following variables were associated with an increased probability of early failure: a mean preoperative pulmonary artery pressure of 19 mm Hg or more (p < 0.001), younger age at operation (p = 0.001), heterotaxy syndrome (p = 0.03), a right-sided tricuspid valve as the only systemic atrioventricular valve (p = 0.001), pulmonary artery distortion (p = 0.04), an atriopulmonary connection originating at the right atrial body or appendage (p = 0.001), the absence of a baffle fenestration (p = 0.002), and longer cardiopulmonary bypass time (p = 0.001). An increased probability of late failure was associated with the presence of a pacemaker before the Fontan operation (p < 0.001). A morphologically left ventricle with normally related great arteries or a single right ventricle (excluding heterotaxy syndrome and hypoplastic left heart syndrome) were associated with a decreased probability of late failure (p = 0.003). CONCLUSIONS: These analyses indicate that early failure has declined over the study period and that this decline is related in part to procedural modifications. A continuing late hazard phase is associated with few patient-related variables and does not appear related to procedural variables.

Child↗

PubMed1997

Functional outcome after the Fontan operation: factors influencing late morbidity.

OBJECTIVES: The purpose of this study was to describe the functional outcome of a large number of patients after modifications of the Fontan operation and to investigate perioperative risk factors that might influence late functional state. METHODS: A comprehensive cross-sectional review of the first 500 patients undergoing a Fontan operation at our institution was undertaken. Those surviving with an intact Fontan circulation were reviewed by questionnaire to assess functional status and medication history. Medical records, chest roentgenograms, echocardiograms, cardiac catheterizations, and laboratory investigations were also reviewed to assess postoperative status. RESULTS: Three hundred sixty-three long-term survivors with an intact Fontan circulation were identified during cross-sectional follow-up. Median age at operation was 5.0 years (range 0.4 to 31 years), and median follow-up was 5.4 years (range 1.7 to 20 years). Most patients (91.1%) were in New York Heart Association class I or II. In a multivariate model, poor (class III or IV) functional state was associated with longer duration of follow-up (p < 0.001), a prior atrial septectomy (p = 0.03), and a prior main pulmonary artery-ascending aorta anastomosis (p = 0.05). CONCLUSIONS: A poor functional outcome is uncommon after the Fontan operation but becomes more frequent with increasing duration of follow-up.

Adolescent↗

PubMed1997

Factors that influence the development of atrial flutter after the Fontan operation.

OBJECTIVES: Atrial flutter is a frequent, potentially fatal complication of the Fontan operation, but risk factors for its development are ill defined. We evaluated clinical features that might predict the development of atrial flutter in patients who had a Fontan operation. METHODS: We evaluated 334 early survivors of a Fontan operation done between April 1973 and July 1991 (mean follow-up, 5.0 +/- 3.8 years). Evaluation included electrocardiography, Holter monitor recordings, and chart review. Modifications of the Fontan operation included an extracardiac conduit (n = 43), an atriopulmonary anastomosis (n = 117), or a total cavopulmonary anastomosis (n = 174). Patient, time, and procedure-related variables were analyzed with respect to the development of atrial flutter. RESULTS: Atrial flutter was identified in 54 (16%) patients at a mean of 5.3 +/- 4.7 years (range 0 to 19.7 years) after Fontan operation. Atrial flutter developed sooner and was more likely to occur in patients who were older at the time of Fontan operation (12.4 +/- 7.6 vs 6.3 +/- 5.2 years; p < 0.001), had a longer follow-up interval (8.7 +/- 3.9 vs 4.4 +/- 3.4 years; p < 0.001), had a prior atrial septectomy or pulmonary artery reconstruction (p < 0.01), and had worse New York Heart Association class symptoms (p < 0.02). The presence of sinus node dysfunction was associated with a higher incidence of atrial flutter (p < 0.001). Although there was a lower prevalence of atrial flutter in those patients with a total cavopulmonary anastomosis, the follow-up for this group was shorter. Anatomic diagnoses, perioperative hemodynamics, and other previous palliative operations were not associated with an increased incidence of atrial flutter. Multivariate analysis identified age at operation, duration of follow-up, extensive atrial baffling, and type of repair as factors associated with the development of atrial flutter after Fontan operation. CONCLUSION: Atrial flutter continues to develop with time after the Fontan operation. Further follow-up is necessary to determine whether a total cavopulmonary anastomosis reduces the incidence of atrial flutter.

Atrial Flutter↗

PubMed1997

Evaluation of a staged treatment protocol for rapid automatic junctional tachycardia after operation for congenital heart disease.

OBJECTIVES: This study sought to 1) develop an efficient treatment protocol for postoperative automatic junctional tachycardia (JT) using conventional drugs and techniques, and 2) identify clinical features associated with this disorder by analyzing a large study group. BACKGROUND: Postoperative JT is a transient arrhythmia that may be fatal after operation for congenital cardiac defects. Its precise cause is unknown. A variety of palliative treatments have evolved, but because of a low incidence of JT, large studies of the most efficient therapeutic sequence are lacking. METHODS: A protocol for rapid JT (>170 beats/min) was adopted in 1986, and was tested in 71 children between 1986 and 1994. Staged therapy involved 1) a reduction of catecholamines; 2) correction of fever; 3) atrial pacing to restore synchrony; 4) digoxin; 5) phenytoin or propranolol or verapamil; 6) procainamide or hypothermia; and 7) combined procainamide and hypothermia. Effective therapy was defined as a sustained reduction of JT rate <170 beats/min within 2 h. Clinical profiles of the study group were contrasted with all patients without JT from this same era to identify features associated with JT. RESULTS: Of the multiple treatment stages, only correction of fever and combined procainamide and hypothermia appeared to be efficacious. By refining the protocol to eliminate nonproductive stages, the time to JT control was significantly shortened for the last 30 patients. Treatment was ultimately successful in 70 of 71 children. Postoperative JT was strongly associated with young age, transient atrioventricular block and operations involving ventricular septal defect closure. CONCLUSIONS: A staged approach to therapy, with emphasis on combined hypothermia and procainamide in difficult cases, appears to be an effective management strategy for postoperative JT. These results may also serve as comparison data for evaluation of newer and promising JT options, such as intravenous amiodarone. Trauma to conduction tissue may play a central role in the etiology of this disorder.

Adolescent↗

PubMed1997

The in vitro construction of a tissue engineered bioprosthetic heart valve.

PROBLEM: Heart valve replacement with either a nonliving xenograft or a mechanical prosthesis is an effective therapy for valvular heart disease. Both of these approaches have limitations, including their inability to grow, repair, and remodel. In addition, a mechanical prosthesis requires long-term anticoagulation therapy. METHODS: This study demonstrates the in vitro creation of tissue engineered heart valve tissue using cardiovascular cells on degradable polymer matrices, 40 heart valve leaflets were created using this technique from two sources. Xenograft leaflets were created using human dermal fibroblasts and bovine aortic endothelial cells (n = 20) or allograft valve leaflets were created using sheep myofibroblasts and sheep endothelial cells (n = 20). A mixed sheep cell population was obtained consisting of endothelial cells and myofibroblasts. Endothelial cells were labelled with acethylated low density lipoprotein (Ac-Dil-LDL) and cells were separated into two groups using an activated cell sorter: LDL positive cells comprised of a pure endothelial cell population and LDL negative cells comprised of mixed cell population containing myofibroblasts and smooth muscle cells. The LDL negative cells were seeded on a synthetic polyglycolic acid (PGA) mesh and grown in vitro to form a tissue-like fibroblast-mesh core. Endothelial cells were then seeded onto the surface of the fibroblast-mesh core, forming a single monolayer. RESULTS: Histological evaluation of these constructs revealed an inner core of LDL negative cells and outer endothelial-like cells which were factor VIII positive. There was no evidence of capillary formation from endothelial cells invading the myofibroblasts and smooth muscle matrix and the endothelial lining appeared complete. CONCLUSIONS: It is feasible to construct allogenic heart valve tissue which could be used to make a valve.

Animals↗

PubMed1997

The efficacy of tranexamic acid versus placebo in decreasing blood loss in pediatric patients undergoing repeat cardiac surgery.

The antifibrinolytic drug, tranexamic acid, decreases blood loss in adult patients undergoing cardiac surgery. However, its efficacy has not been extensively studied in children. Using a prospective, randomized, double-blind study design, we examined 41 children undergoing repeat sternotomy for repair of congenital heart defects. After induction of anesthesia and prior to skin incision, patients received either tranexamic acid (100 mg/kg, followed by 10 mg.kg-1.h-1) or saline placebo. At the onset of cardiopulmonary bypass, a second bolus of tranexamic acid (100 mg/kg) or placebo was administered. Total blood loss and transfusion requirements during the period from protamine administration until 24 h after admission to the intensive care unit were recorded. Children who were treated with tranexamic acid had 24% less total blood loss (26 +/- 7 vs 34 +/- 17 mL/kg) compared with children who received placebo (univariate analysis P = 0.03 and multivariate analysis P < 0.01). Additionally, the total transfusion requirements, total donor unit exposure, and financial cost of blood components were less in the tranexamic acid group. In conclusion, tranexamic acid can reduce perioperative blood loss in children undergoing repeat cardiac surgery.

Antifibrinolytic Agents↗

PubMed1997

Tissue engineering of cardiovascular structures.

Congenital and acquired diseases of the heart valves and great arteries are leading causes of morbidity and mortality. Current prosthetic or bioprosthetic replacement devices are imperfect and subject patients to one or more ongoing risks including thrombosis, limited durability, increased susceptibility to infection, and need for reoperations due to lack of growth. Tissue engineering (TE) is a new discipline that offers the potential to create replacement structures from autologous cells and biodegradable polymers. Because TE constructs contain living cells, they may have the potential for growth and self-repair and remodeling. Cardiac valve leaflets and large conduit arteries have been made with the TE approach. These TE structures have functioned in the pulmonary circulation of growing lambs for up to 4 months and have demonstrated 1) structural organization to resemble normal valve and artery, 2) satisfactory physiologic function, 3) lack of thrombus formation, and 4) growth.

Animals↗