Improving compliance with the dialysis prescription as a strategy to increase the delivered dose of hemodialysis: an ESRD Network 4 quality improvement project

Delivery of an inadequate dose of hemodialysis is associated with a significant increase in the relative risk of both hospitalization and death. We hypothesized that noncompliance with the dialysis prescription, defined as failure to achieve the prescribed blood flow, failure to dialyze for the prescribed duration, or failure to use the prescribed dialyzer, was a significant factor in patients not achieving a urea reduction ratio (URR) of > or =0.65. We identified the 29 dialysis facilities in ESRD Network 4 that had the lowest average URR and/or lowest percent of patients with a URR > or =0.65 based on quarterly data reports. Each facility was surveyed by review of all dialysis treatment sheets from a single week by network staff to evaluate for noncompliance with the dialysis prescription. Facility-specific data were reported back to each facility. Each facility was required to develop a facility-specific quality improvement plan after receiving intensive education on the quality improvement process. After 9 months the facilities were resurveyed. Although the compliance with the dialysis prescription decreased from 54.0% to 53.6% (P =.026), the delivered URR increased from 0.679 +/- 0.072 to 0.688 +/- 0.070 (P =.026) with an increase in the percentage of patients with a URR > or = 0.65 from 69.7% to 75% (P =.0096). Kt/V increased from 1.37 +/- 0.26 to 1.41 +/- 0.27 (P =. 0001). Analysis of the process changes instituted by the individual facilities showed an increase in the prescribed dose of dialysis. Thus, although the process goal of improved compliance with the dialysis prescription was not achieved, the outcome goal of an increased delivered dose of dialysis was met through an alternative process change of an augmented dialysis prescription.

Barriers to the delivery of adequate hemodialysis in ESRD Network 4

Dialysis dose has been established as a determinant of morbidity and mortality in chronic hemodialysis patients. To identify remediable barriers to the delivery of adequate hemodialysis, we examined factors that affected adherence to prescribed dialysis dose. End-Stage Renal Disease (ESRD) Network 4 facilities that fell into the lowest quintile in measures of dialysis adequacy were studied. At the time of this study, Network 4 was composed of 178 dialysis facilities in Delaware and Pennsylvania. Those 29 facilities had an average delivered urea reduction ratio (URR) of <0.67 and/or 71% of patients with a URR of 0.65. (The mean URR value of Network 4 was 0. 699 with a compliance ratio of 80%.) Dialysis treatment sheets were reviewed for all patients in the 29 facilities for all treatments during a calendar week. Predialysis and postdialysis blood urea nitrogen (BUN) values from 1 treatment during this week were used to calculate URR and Kt/V. A total of 1,339 patients with a mean age of 61.9 +/- 15.1 years and a mean duration of ESRD of 3.4 +/- 3.3 years were dialyzed in the 29 units. Mean prescribed duration of dialysis (T) was 219 +/- 26 min. with a mean blood flow rate (BFR) of 393 +/- 62 mL/min. Concordance between the prescribed and delivered T (-5 min), BFR (-50 mL/min), and hemodialyzer were assessed, by patient, for each treatment (Tx). Characteristics of a delivered Kt/V < 1.2 were duration <4 hours, BFR < 350 mL/min, patient weight > 100 kg, and delivered BFR 50 mL/min less than prescribed BFR. Multivariate analysis of the relationship between delivered dose of dialysis and patients and treatment characteristics identified black race, male gender, and younger age as demographic factors associated with low delivered dose. Potential remediable barriers identified by this analysis included reduced treatment time (>10%) and use of catheters for angioaccess. These data suggest components of the dialysis process that might be targeted in future quality improvement projects to improve the adequacy of dialysis delivery.

Early results and medium-term follow-up of stent implantation for mild residual or recurrent aortic coarctation

BACKGROUND

Optimal timing and mode of treatment for patients with aortic coarctation remains controversial, particularly when the degree of obstruction is mild. Surgery, balloon dilatation, and stent implantation have all proven effective in the treatment of moderate or severe obstruction. In this report, we describe the use of stents to treat coarctation in a heterogeneous population, including patients with relatively mild obstruction.

METHODS

Retrospectively, we studied the results of stent implantation in 33 patients, children and young adults, who underwent catheterization for treatment of coarctation. Patients with isolated coarctation, as well as those with associated cardiac defects, were included. The median systolic pressure gradient of our patients was 25 mm Hg.

RESULTS

Patients had an acute decrease in systolic blood pressure gradient (25 mm Hg to 5 mm Hg, P <.001) and an increase in lumen diameter (8 mm to 13 mm, P <.001). When 16 patients were recatheterized during the follow-up period, gradients remained decreased (30 mm Hg to 14 mm Hg, P <.001) compared with prestent values. Ventricular end-diastolic pressure, which was increased in 82% of patients at the time of initial catheterization, decreased from 17 mm Hg to 14 mm Hg (P =.002). Although the procedure was generally safe, serious complications did occur.

CONCLUSIONS

Stent implantation represents a therapeutic option that can safely and effectively reduce gradient in challenging patients with mild postoperative coarctation. Furthermore, our data suggest that aortic obstruction often coexists with ventricular diastolic dysfunction in these patients and that relief of obstruction may play a role in improvement of function.

Echocardiographic predictors of coronary artery pathology in pulmonary atresia with intact ventricular septum

Coronary artery pathology is a major determinant of treatment strategy and outcome in patients with pulmonary atresia and intact ventricular septum (PA/IVS). For this reason, infants with PA/IVS routinely undergo preoperative cardiac catheterization. The goal of this study was to identify echocardiographic predictors of coronary artery pathology in infants with PA/IVS. The initial preoperative echocardiograms of 30 consecutive infants with PA/IVS (median age at diagnosis 1 day) were reviewed for indexes predicting the degree of coronary pathology. The tricuspid valve (TV) annulus diameter Z- score was determined and evidence of abnormal flow in the coronary arteries by Doppler was evaluated. Coronary pathology was defined by angiography and graded as: 0 = no fistulae; 1 = fistulae/no right ventricular (RV)-dependent coronary arteries; 2 = fistulae with 1 RV-dependent coronary; 3 = fistulae with >/=2- vessel RV-dependent coronary arteries. Outcome was classified as: 2 ventricles, "1.5" ventricles, and 1 ventricle. By angiography, 30% of the patients had grade 0 coronary pathology, 30% had grade 1, 20% had grade 2, and 20% had grade 3. There was 1 death in a patient with grade 3 coronary pathology. Among the survivors (median age at follow-up 28. 6 months), biventricular circulation existed in 12 patients (41%), 7 patients (24%) were 1.5, and 10 (34%) were 1 ventricle. All patients with TV Z-score </=-2 had coronary fistulae by angiography and 35% had grade 3 coronary pathology. None of the patients with grade 2 or 3 coronary artery pathology had a TV Z-score >-2.5. The sensitivity, specificity, positive, and negative predictive values of TV Z-score </=-2.5 in predicting RV dependent coronary arteries were 100%, 83%, 80%, and 100%, respectively. Thus, in newborns with PA/IVS the echocardiographically derived TV Z-score predicts the likelihood of coronary artery fistulae and RV-dependent coronary arteries and can be used to rationalize the need for preoperative diagnostic catheterization.

Left superior vena cava connection to unroofed coronary sinus associated with positional cyanosis: successful transcatheter treatment using Gianturco-Grifka vascular occlusion device

A persistent left superior vena cava connection to an unroofed coronary sinus is a rare cardiac anomaly that is associated with a variable degree of cyanosis. We report an infant with this condition and the unusual feature of cyanosis dependent on head position. When the patient's head was rotated to the left, he developed severe stenosis of the left internal jugular vein, enlarged cervical collateral veins that connected to the right superior vena cava and had an oxygen saturation 95%. When the patient's head was rotated to the right, the left internal jugular vein was widely patent and systemic oxygen saturation decreased to 87%. There was no right ventricular volume overload. Temporary occlusion of the left superior vena cava documented tolerable proximal venous pressure. Cyanosis was relieved by transcatheter closure of the left superior vena cava with a Gianturco-Grifka vascular occlusion device. Cathet. Cardiovasc. Intervent. 48:369-373, 1999.

Repeat balloon dilation of congenital valvar aortic stenosis: immediate results and midterm outcome

While balloon dilation (BD) has become the initial treatment for congenital valvar aortic stenosis (CVAS) at many institutions, repeat BD for recurrent obstruction has been reported only in a few. Between January 1985 and December 1996, 298 patients (70 neonates) underwent BD, 34 of whom underwent a repeat BD without mortality. A greater proportion of neonates had a repeat BD (26% vs. 8%, P < 0.001). At repeat BD (1 day-7.5 years post initial BD), the mean peak-to-peak gradient was reduced from 67+/-24 to 36+/-16 mm Hg (P < 0.0001). Aortic regurgitation (AR) increased immediately in 26%, being moderate or more in 24%. During a mean follow-up of 5.2 years, there was one surgically related death. Of the 33 survivors, 6 had surgery for residual stenosis and/or AR. Among the remaining 27 patients, 96% were asymptomatic, the peak instantaneous aortic valve Doppler gradient was 50+/-15 mm Hg with AR absent in 8%, mild in 62%, and moderate or more in 31%. In conclusion, repeat BD is effective and without mortality. AR was at least moderate in 24% of patients immediately after a second BD. Repeat BD was more common in patients who underwent the initial BD as neonates.

Preoperative management of pulmonary venous hypertension in hypoplastic left heart syndrome with restrictive atrial septal defect

A severely restrictive atrial septal defect (ASD) in neonates with hypoplastic left heart syndrome (HLHS) results in pulmonary venous hypertension, pulmonary edema, and intractable hypoxia. Between January 1983 and June 1998, 21 of 355 neonates presenting with HLHS (5.9%) underwent cardiac catheterization at median age 1 day (range 0 to 25), for creation or enlargement of a restrictive or absent interatrial communication. One patient died during preliminary angiography. Three underwent blade septostomy with 2 procedure-related deaths, and 1 had balloon atrial septostomy (BAS); all 4 died before surgical intervention. Fifteen underwent Brockenbrough atrial septoplasty with transatrial needle puncture and serial balloon dilations of the new ASD, 5 after unsuccessful BAS. The most recent patient had a stent placed across the atrial septum after transatrial needle puncture. In the 16 patients treated with septoplasty or stent, oxygen saturation increased from 50 +/- 4% to 83 +/- 2% (p <0.0001) and transatrial pressure gradient decreased from 16 +/- 1 to 6 +/- 1 mm Hg (p <0.0001). One patient died awaiting transplantation, supportive care only was requested in 1, and 14 underwent stage 1 palliation. Eight of 14 (57%) survived to hospital discharge. Six of 7 (86%) survived bidirectional Glenn and the 3 who have undergone fenestrated Fontan are alive. In neonates with HLHS, a restrictive ASD resulting in profound cyanosis demands urgent intervention. BAS is frequently unsuccessful and blade septostomy has high mortality. Pulmonary venous hypertension can be adequately relieved by Brockenbrough atrial septoplasty or stenting, allowing stabilization before reconstructive surgery or while awaiting transplant.

Transvascular balloon dilation for neonatal critical aortic stenosis: early and midterm results

OBJECTIVES

We evaluated our immediate and midterm (mean 4.3 years) results of balloon dilation of critical valvular aortic stenosis in 33 neonates.

BACKGROUND

Balloon dilation has been used as an alternative to surgical treatment. Reports to date consist of small series (largest 16 babies) with short-term follow-up (longest 4.8 years).

METHODS

From 1985 to 1991, 33 neonates had dilation at a mean age of 13 days and a mean weight of 3.4 kg. Nineteen of the neonates (58%) were intubated and received prostaglandins, and 94% had other cardiac abnormalities.

RESULTS

The dilation was completed retrograde in 31 of the neonates (umbilical artery in 11 and femoral artery in 20) and anterograde (femoral vein) in 2. The average immediate peak gradient and left ventricular end-diastolic pressure reductions were 54% and 20%, respectively. The overall mortality rate was 12% (three early deaths and one late). All 20 neonates dilated through a femoral artery initially had pulse loss with restoration in 35% after thrombolytic therapy. At 8.3 years, survival and freedom of reintervention probability rates were 88% and 64%, respectively. At mean 4.3 years of follow-up, 83% of the survivors were asymptomatic; Doppler study revealed a maximal instantaneous gradient < 50 mm Hg in 65% of neonates and significant aortic regurgitation in 14%.

CONCLUSIONS

This study confirms that dilation of aortic stenosis in neonates is effective; reintervention (mostly redilation) is frequent (40%); and midterm survival is encouraging (88%).

Tetralogy of Fallot with diminutive pulmonary arteries: preoperative pulmonary valve dilation and transcatheter rehabilitation of pulmonary arteries

OBJECTIVES

This study sought to determine the results of a novel transcatheter management approach in tetralogy of Fallot with diminutive pulmonary arteries.

BACKGROUND

Tetralogy of Fallot with diminutive pulmonary arteries and severe pulmonary stenosis is rare and resembles tetralogy of Fallot with pulmonary atresia: There is a high incidence of aortopulmonary collateral channels, arborization abnormalities, stenoses and need for multiple operations. Because a combined catheter-surgery approach facilitates repair in these patients, such an approach may benefit those with diminutive pulmonary arteries and pulmonary stenosis.

METHODS

Clinical, catheterization and surgical data were studied retrospectively for 10 such patients undergoing preoperative pulmonary valve balloon dilation, among other transcatheter interventions, from January 1989 to January 1995.

RESULTS

Initially, the Nakata index ranged from 20 to 98 mm2/m2 (mean 67 +/- 28 mm2/m2). The pulmonary valve was first balloon dilated (mean balloon/annulus 1.5 +/- 0.3), and the mean initial valve annulus Z score (-4.0 +/- 1) increased to -33 +/- 1.1 (p < 0.01) Other interventions included branch pulmonary artery balloon dilation (7 patients, 23 vessels) and coil embolization of aortopulmonary collateral channels (8 patients, 31 collateral channels). At preoperative follow-up catheterization, the mean pulmonary annulus Z score was -3.1 +/- 0.7, and the Nakata index increased to 143 +/- 84 mm2/m2 (p < 0.03). All patients underwent complete surgical repair successfully. At a mean follow-up period of 2.6 +/- 2 years, right ventricular pressure was < 70% systemic in all patients and < 50% systemic in seven.

CONCLUSIONS

In patients with tetralogy of Fallot, severe pulmonary stenosis and diminutive pulmonary arteries, initial pulmonary valve balloon dilation increases the annulus Z score and anterograde pulmonary blood flow and facilities simultaneous coiling of aortopulmonary collateral channels and access for branch pulmonary artery dilation, all of which results in pulmonary artery growth, simplifying surgical management.

Midterm results of balloon dilation of congenital aortic stenosis: predictors of success

OBJECTIVES

We evaluated patient and procedural characteristics that influence the midterm success of balloon dilation of congenital aortic stenosis.

BACKGROUND

Balloon dilation is a new treatment for congenital aortic stenosis. Factors that influence midterm success are unknown.

METHODS

We performed a retrospective review of 148 children >1 month old who underwent balloon dilation for aortic stenosis.

RESULTS

Balloon dilation was successful in 87% of patients, with a procedural mortality rate of 0.7%. The average immediate peak to peak gradient reduction was 56.4 +/- 19.9% (mean +/- SD). Prior valvotomy was the only factor that significantly reduced the immediate gradient reduction after dilation (47.1 +/- 21.8% vs. 57.8 +/- 19.6%, p < 0.01). Survival after dilation was 95% at 8 years. Seventy-five percent of patients were free of repeat intervention 4 years after dilation, whereas 50% remained free of repeat intervention at 8 years. Asymmetrically thick valve leaflets (risk ratio [RR] 0.17, p < 0.01) and prior aortic valvotomy (RR 0.35, p = 0.02) decreased the risk of repeat intervention. Aortic regurgitation grade > or = 3 (RR 4.27, p = 0.04) and residual gradient after dilation (RR 1.63 for 10 mm Hg, p < 0.01) increased the risk.

CONCLUSIONS

The 8-year survival rate after dilation was 95% with 50% of patients free of repeat intervention. Factors that increased the risk for repeat intervention included symmetrically thin or thick aortic valve leaflets, regurgitation grade > or = 3 after dilation and a high residual gradient after dilation. The incidence of repeat intervention after dilation was high owing to its palliative nature.

New developments in intracardiac and intravascular devices for congenital heart disease

Techniques of transcatheter device placement for treatment of pediatric congenital heart disease have developed substantially since their introduction 20 years ago. Patent ductus arteriosus occlusion can be accomplished by umbrella deployment or coil placement. Intracardiac defects can be closed with umbrella or buttoned devices. Stenoses of vessels or conduits that are only temporarily relieved with balloon dilation can be effectively expanded with intravascular stents. Recent procedural modifications have been introduced in an attempt to minimize the size of the delivery sheath and reduce complications that can arise from device embolization. Transcatheter device placement can be an important adjunct to surgery for correction or palliation of congenital heart lesions.

Prolongation of RV-PA conduit life span by percutaneous stent implantation. Intermediate-term results

BACKGROUND

Right ventricle-to-pulmonary artery (RV-PA) homografts and bioprosthetic conduits are commonly used to palliate various types of complex congenital heart disease. These conduits frequently develop progressive obstruction and require surgical replacement. This report reviews our experience implanting balloon-expandable stents to relieve conduit obstruction and delay reoperation.

METHODS AND RESULTS

A retrospective review identified 44 patients who underwent placement of 48 stents in obstructed RV-PA conduits. Median patient age was 6.9 years (range, 7 months to 30 years), and median follow-up time was 14.2 months (range, 0 to 48 months). Stent implantation initially decreased the RV-PA pressure gradient from 61.0 +/- 16.9 to 29.7 +/- 11.9 mm Hg (P < or = .001) and the right ventricular-to-systemic arterial pressure ratio from 0.92 +/- 0.17 to 0.63 +/- 0.20 (P < or = .001). The diameter of the stenotic region expanded from 9.3 +/- 3.5 to 12.3 +/- 3.3 mm in the anteroposterior view (P < or = .001) and from 6.6 +/- 2.9 to 10.9 +/- 2.5 mm in the lateral view (P < or = .001). During the follow-up period, 2 patients had their stents redilated, 7 had additional conduit stents deployed, and 14 underwent surgical replacement of their conduits. Actuarial freedom from conduit reoperation was 65% at 30 months postprocedure. Seven patients were found to have fractured stents on follow-up, suggesting an important role for external compressive forces in conduit failure. Recatheterization in 16 patients a median of 11.8 months (3 to 48 months) postprocedure demonstrated hemodynamic evidence of recurrent obstruction despite sustained enlargement at the previously stented sites. Complications included stent displacement (n = 1), bacterial endocarditis (n = 1), and false aneurysm formation (n = 1). One patient died awaiting conduit replacement surgery.

CONCLUSIONS

Stent implantation in obstructed RV-PA conduits results in significant immediate hemodynamic and angiographic improvement. In a subgroup of patients, the procedure prolongs conduit life span by several years and increases the interval between conduit reoperations. Recurrent obstruction is caused by external compression and progressive stenosis outside the stented region.

Coronary artery abnormalities detected at cardiac catheterization following the arterial switch operation for transposition of the great arteries

Because the arterial switch operation has become the routine surgical approach for transposition of the great arteries, there is increasing awareness of adverse sequelae in some survivors. For the arterial switch to be considered the procedure of choice for transposition of the great arteries, long-term patency and normal function of the translocated coronary arteries must be achieved. We reviewed the cineangiograms and hemodynamic data in 366 patients who underwent postoperative catheterization after arterial switch operation. Of these, 13 patients (3%) had previously unsuspected coronary abnormalities diagnosed angiographically. No patient had noninvasive evidence of resting systolic dysfunction. Findings included left main coronary artery stenosis (n = 3) or occlusion (n = 2), anterior descending coronary artery stenosis (n = 1) or occlusion (n = 2), right coronary artery stenosis (n = 1) or occlusion (n = 1), and small coronary artery fistulas (n = 3). One patient died suddenly 3.3 years after surgery, 1 patient is lost to follow-up, and the remaining 10 patients are alive and asymptomatic up to 11 years after surgery.

Transcatheter closure of ventricular septal defects: hemodynamic instability and anesthetic management

The technique of transcatheter ventricular septal defect (VSD) device closure may be associated with significant hemodynamic instability. The anesthetic records and catheterization data of 70 consecutive transcatheter VSD closures between February 1989 and September 1992 were reviewed, and risk factors associated with hemodynamic instability evaluated. In 28 of 70 procedures (40%), hypotension (> 20% decrease in systolic blood pressure from baseline) occurred; 12 responded to administration of fluids intravascularly alone, whereas 16 patients required additional acute resuscitation. Significant dysrhythmias occurred during 20 (28.5%) anesthetics associated with hypotension and requiring treatment or catheter withdrawal. ASA physical status, precatheterization indication for device placement, and patient size were not predictive of hemodynamic instability during the procedure. Blood transfusions were necessary in 38 (54.4%) cases and were size-related, with patients weighing less than 10 kg requiring a significantly larger transfusion volume (25.1 +/- 12.4 mL/kg). After 35 procedures (50%) patients were admitted directly to the intensive care unit (ICU) due primarily to hemodynamic instability or procedure duration; 24 (68%) required mechanical ventilation. No deaths occurred; there was no late morbidity due to catheterization-related events. Intravenous sedation was used for the initial catheterizations, maintained with a combination of midazolam, ketamine, and morphine. Subsequently general intravenous or inhaled anesthesia was predominantly used during transesophageal echocardiography and internal jugular vein cannulation. We conclude that hemodynamic instability is common during device closure of VSDs, and is likely to be an inescapable feature of these procedures in many patients because of the technique necessary for device placement.

Intraaortic spring coil loops: early and late results

OBJECTIVES

Our aim was to determine the late fate of intraaortic spring coil loops after embolization of aortopulmonary vessels.

BACKGROUND

In some aortopulmonary collateral vessels and patent ductus arteriosi, the narrowest segment is close to the aorta; coils used to close such vessels will "straddle" the lesion, allowing one or more coil loops to protrude into the aortic lumen. The consequences of this procedure are unknown.

METHODS

We reviewed the cineangiograms of all patients who had at least one aortopulmonary collateral vessel or patent ductus arteriosus closure between January 1, 1988 and August 31, 1993. From this group, 53 patients had multiple-plane angiographic evidence of intraaortic coil loops. All subsequent cineangiograms were reviewed to determine coil position or movement and evidence of recanalization or endothelial coverage of the coil loop. We also reviewed each hospital record or communicated directly with referring physicians to identify any subsequent complications such as emboli or endocarditis.

RESULTS

Of the 53 patients with intraaortic coil loops, 49 patients had closure of one or more aortopulmonary collateral vessels (59 vessels), and 4 had closure of a patient ductus arteriosus (4 vessels). Patient follow-up ranged from 1 day to 66 months (median 20 months); follow-up was not available in 6 patients. Five of the 53 patients (9.3%; 95% confidence limits [CL] 3.1% to 20.7%) died at operation or of end-stage heart failure. Patients with late angiography had no residual flow in 31 of 35 aortopulmonary collateral vessels (88.6%; 95% CL 73.3% to 96.8%), and 0.5 mm separated the coil and aortic contrast column in all 12 coils with adequate angiography, suggesting endothelial coverage of the intraaortic coil loop. No episodes of stroke, embolic events, endocarditis or coil migration were reported.

CONCLUSIONS

Although coil occlusion of aortopulmonary collateral vessels or patent ductus arteriosi may produce intraaortic coil loops, endothelialization appears routine. No late complications associated with intraaortic coil loops were observed.

Balloon dilation of critical valvar pulmonary stenosis in the first month of life

Between 1985 and 1992, 36 consecutive neonates, aged 1-29 days, weight 2.4-5.0 kg, with critical valvar pulmonary stenosis underwent attempted balloon dilation (BD). At catheterization, 30 were on prostaglandin (PGE1) therapy and 20 were intubated. The valve was successfully crossed and dilated in 34/36 (94%), including three with an echocardiographic diagnosis of valvar pulmonary atresia and a right ventricle of adequate size. The valve was first dilated with a 2- to 5-mm balloon and then with serially larger ones (up to 12 mm) to a final balloon/annulus value of 126%. The RV/systemic pressure value fell from 150 +/- 32 to 83 +/- 30%, O2 saturation rose from 91 +/- 6% to 96 +/- 4%, and PGE1 was discontinued at the end of the procedure. There were 11 complications (31%) including one early death from sepsis and necrotizing enterocolitis, endocarditis in another, two myocardial perforations, one femoral-iliac vein tear, and one transient pulse loss. A repeat BD was carried out in five patients, two of whom subsequently had surgery. At follow-up (33 +/- 23 months), the 31 patients managed by BD alone were well and had echocardiographic gradients of < 30 mm Hg in 90% and pulmonary regurgitation, considered mild in most, in 52%. In neonates with critical valvar pulmonary stenosis, we believe BD mortality is less than with surgery and is the treatment of choice.

Balloon aortic valvuloplasty in the young adult with congenital aortic stenosis

Although balloon aortic valvuloplasty (BAV) is effective in the acute management of valvar aortic stenosis (AS), sustained benefit of this technique has been shown to vary in differing age groups. The role of BAV in the young adult with congenital, nondegenerative AS is poorly defined. The catheterization results and follow-up echocardiographic data were reviewed for all patients (n = 18) between the ages of 17 and 40 years (mean 23 +/- 7) undergoing BAV at our institution between March 1986 and January 1992. Peak-to-peak systolic ejection gradient was reduced by 55%, from 85 +/- 29 to 38 +/- 17 mm Hg (p < 0.001). Aortic valve area increased from 0.9 +/- 0.2 to 1.1 +/- 0.3 cm2 (p = 0.003). Results of dilation were inadequate in 2 patients. There were no deaths, myocardial infarction, or embolic events. The 16 "effectively" dilated patients were followed with serial echocardiography for a period of 1 to 82 months, demonstrating persistent gradient relief in most patients (maximal instantaneous gradient at follow-up, 55 +/- 17 vs 79 +/- 22 mm Hg before dilation, p < 0.001). Aortic valve replacements were performed in 5 patients, 2 with unsuccessful initial dilations. At the time of the most recent echocardiogram, 8 of 16 patients remained "incident free," with no subsequent catheterization or surgical interventions, a maximal instantaneous gradient of < or = 55 mm Hg, no more than moderate aortic regurgitation, and preserved ventricular function.(ABSTRACT TRUNCATED AT 250 WORDS)

Transesophageal echocardiographic guidance of transcatheter ventricular septal defect closure

OBJECTIVES

This report describes transesophageal echocardiographic guidance of transcatheter closure of ventricular septal defects and its value as an adjunct to fluoroscopy and angiography in this procedure.

BACKGROUND

Experience with transcatheter closure of ventricular septal defects has identified a diverse group of patients in whom it may be the procedure of choice. Although facilitating other interventional procedures, such as transcatheter closure of atrial septal defects, the value of transesophageal echocardiographic guidance for transcatheter ventricular septal defect closure has not been documented.

METHODS

All patients who underwent ventricular septal defect closure with transesophageal echocardiographic guidance before November 1992 were included. Angiograms and echocardiograms were reviewed to evaluate device position and relation to valve tissue during placement and to assess residual flow after device implantation. The ability of transesophageal echocardiography to assess these variables was compared with fluoroscopy and angiography.

RESULTS

Transesophageal echocardiographic guidance was used in 31 of the 83 catheterizations involving transcatheter ventricular septal defect closure performed between February 1990 and November 1992. Under transesophageal echocardiographic guidance, 45 devices were implanted: 23 in muscular ventricular septal defects, 17 in residual postoperative patch margin defects and 5 in other ventricular septal defects. Transesophageal echocardiographic guidance enhanced assessment of device position and proximity to valve structures and markedly improved assessment of residual flow. Assessment of residual flow with transesophageal echocardiography eliminated the need for multiple angiograms in some patients. Combining transesophageal echocardiography with fluoroscopy and angiography provided the most information.

CONCLUSIONS

Transesophageal echocardiography facilitates transcatheter closure of ventricular septal defects by improving assessment of device position and effectiveness of closure. It is indicated when device placement is likely to be difficult or may interfere with valve structures or when multiple interventional procedures are anticipated.

Severe congenital mitral stenosis in infants

BACKGROUND

Despite current medical and surgical therapy, infants with symptomatic congenital mitral stenosis (CMS) continue to have high rates of morbidity and mortality. Catheter balloon dilation has been successful in relieving symptoms in a few older children with CMS but has not been evaluated in infants.

METHODS AND RESULTS

We reviewed the records of 85 infants with CMS to assess severity of CMS, associated cardiac lesions, echocardiographic morphological appearance of the mitral valve, treatment, and outcome. There were five valve morphologies identified: "typical" hypoplastic mitral valve with symmetric papillary muscles (SYMM, 52%), supravalvar mitral ring (SVMR, 20%), double-orifice mitral valve (DOMV, 11%), hypoplastic mitral valve with asymmetric papillary muscles (ASYMM, 8%), and parachute mitral valve (PARA, 8%). Of the 85 infants, 31 (36%) were severely symptomatic, requiring intervention within the first 2 years. Balloon dilation was performed in 18 infants (age, 8.7 +/- 5.7 months; weight, 5.9 +/- 1.9 kg) and valve surgery in 13 (age, 10.9 +/- 5.9 months; weight, 6.7 +/- 2.1 kg). Balloon dilation decreased the peak transmitral gradient (LAa-LVED) > 30% in 15 of 18 initial attempts, from 20.3 +/- 8.2 to 10.9 +/- 4.9 mm Hg (P < .001), and the mitral valve area increased from 0.7 +/- 0.3 to 1.0 +/- 0.5 cm2/M2 (n = 10, P = .01). No infants died during the initial balloon dilation, although 2 of 3 died during a repeat procedure for restenosis. Other complications included significant mitral regurgitation in 7 of 18 patients (39%), 4 of whom had SVMR. Of the 18 infants, 8 (44%) had persistent symptomatic improvement at a mean follow-up of 14 months (range, 2 to 32 months). The 2-year survival after balloon dilation was 70%; 40% remained free of repeat intervention. Mitral valve surgery in 13 infants consisted of SVMR resections in 7, mitral valve replacements in 4, and LA-to-LV aortic valved homografts in 2. The operative mortality was 30%. Sustained improvement occurred in 8 (6 with SVMR) at 11 to 62 months of follow-up (mean, 30 months), with a 2-year survival of 60%.

CONCLUSIONS

Infants with severe CMS have 2-year mortality rates approaching 40% regardless of treatment modality. Balloon dilation significantly reduces the transmitral gradient in the majority, but symptomatic improvement persists in only 40%. Procedure-related mortality was associated with repeat balloon dilation in patients with left ventricular hypoplasia. Balloon dilation of "typical" CMS can provide symptomatic relief in many infants, allowing postponement of valve replacement, although infants with SVMR do better with surgical management.

Traumatic aortopulmonary window as a complication of pulmonary artery balloon angioplasty: transcatheter occlusion with a covered stent. A case report

We describe a case in which pulmonary artery balloon angioplasty was complicated by formation of an aortopulmonary window, a previously unreported complication associated with this technique. A novel transcatheter approach for occluding the defect, a covered stent, was utilized. Deployment of the covered stent significantly reduced the shunt, allowed for clinical stabilization, and averted the need for emergency surgical intervention.

High pressure balloon angioplasty for branch pulmonary artery stenosis: early experience

OBJECTIVES

The aim of this study was to evaluate the efficacy and safety of high pressure balloons (17 to 20 atm, Blue Max, Meditech) to dilate branch pulmonary artery stenosis.

BACKGROUND

The low success rate (50% to 60%) for angioplasty of branch pulmonary artery stenosis using low pressure balloons is due primarily to the inability to eliminate the balloon waist. Hence, higher inflation pressures may improve results.

METHODS

Hemodynamic and angiographic data from 52 patients (0.3 to 34.8 years old) who underwent high pressure balloon dilation of branch pulmonary artery stenosis between October 1990 and February 1992 were reviewed retrospectively, as were data from previous low pressure dilations in these patients. Common diagnoses included tetralogy of Fallot (n = 9), tetralogy of Fallot with pulmonary atresia (n = 23), single ventricle (n = 8) and isolated congenital pulmonary stenosis (n = 7). The 52 patients had 72 vessels dilated. Criteria for success were a > or = 50% increase in vessel diameter or a > 20% decrease in right ventricular to aortic pressure ratio.

RESULTS

Of 36 vessels with previously unsuccessful low pressure balloon dilation, 23 (63%) were successfully dilated with high pressure balloons. Of the 36 remaining vessels, 29 (81%) were successfully dilated with high pressure balloons. Factors associated with success were stenosis at a surgical anastomosis and disappearance of the balloon waist with dilation. Aneurysms developed in three vessels. Complications occurred in seven patients (13%); in two patients the distal pulmonary artery was perforated by a stiff guide wire, causing death in one.

CONCLUSIONS

Dilation of stenotic peripheral pulmonary arteries with high pressure balloons improves the success rate of angioplasty both in patients who have had unsuccessful dilation with a low pressure balloon and in those without previous attempted dilation.

Implantation and intermediate-term follow-up of stents in congenital heart disease

BACKGROUND

Balloon-expandable stents (Johnson and Johnson Interventional Systems) have been in use for congenital heart disease since late 1989. They have made possible treatment in previously untreatable branch pulmonary artery stenoses and systemic venous stenosis. The purpose of this report is to detail the results and intermediate-term follow-up of stents used for treatment of congenital heart disease.

METHODS AND RESULTS

Eighty-five patients underwent placement of 121 stents in Houston and Boston. Fifty-eight patients had stents put in pulmonary arteries, nine had stents in conduits or outflow tracts, and 21 had stents in venous stenoses or narrowed Fontan anastomoses. (Three patients had stents in two locations.) These stent procedures resulted in gradient reduction from 55.2 +/- 33.3 to 14.2 +/- 13.5 mm Hg in pulmonary arteries, from 41.4 +/- 26.0 to 20.7 +/- 17.0 mm Hg in conduits or outflow tracts, and from 9.8 +/- 6.9 to 2.4 +/- 3.1 mm Hg in venous stenoses or Fontan anastomoses. Diameter of narrowings increased from 4.6 +/- 2.3 to 11.3 +/- 3.2 mm in the pulmonary artery, from 8.8 +/- 3.6 to 12.7 +/- 2.6 in conduits, and from 3.8 +/- 2.9 to 11.3 +/- 2.8 in venous stenoses. Follow-up has shown stent fracture in one patient, restenosis in one, and sudden death in one. Recatheterization has been done in 38 patients an average of 8.6 months after stent installation. Compared with immediately postimplant data, there was no significant change in luminal diameter or pressure gradient. Redilation was performed in 14 patients (17 stents) 1 week to 24 months after implantation (mean, 10.2 months), with a small but significant increase in stenosis diameter.

CONCLUSIONS

We conclude that stent treatment of vascular stenoses in congenital heart disease retains efficacy at medium-term follow-up and offers a much-improved outlook for patients with these lesions.

Generalized arteriopathy in Williams syndrome: an intravascular ultrasound study

OBJECTIVES

We used intraluminal ultrasound imaging to provide additional information about the vascular pathology in Williams syndrome.

BACKGROUND

The cardiovascular pathology of Williams syndrome consists of medial hypertrophy in both systemic and pulmonary arteries, which results in lumen narrowing.

METHODS

Systemic and pulmonary arteries were examined in vivo using intravascular ultrasound imaging (5F, 30-MHz catheter) in three children with Williams syndrome.

RESULTS

All arteries exhibited severe wall thickening with secondary lumen narrowing. Balloon dilation of a branch pulmonary artery in two children resulted in a significant localized increase in lumen caliber associated with a tear in the vessel wall.

CONCLUSIONS

Intravascular ultrasound imaging in patients with Williams syndrome may permit better understanding of the pathophysiology of the syndrome and a more rational approach to therapeutic interventions.

Transcatheter closure of atrial and ventricular septal defects

The clamshell double umbrella (Bard Clamshell Septal Umbrella, USCI Division, C. R. Bard, Billerica, MA) was developed to allow closure of septal defects, both atrial and ventricular. The device and delivery system and the techniques for implanting the device in atrial and ventricular defects are described in detail. Although fractures of the arms supporting the umbrellas in some patients have lead to modification of the device, the early experience in clinical trails are encouraging.

Enlarged bronchial arteries after early repair of transposition of the great arteries

OBJECTIVES

This study was undertaken to define the incidence of enlarged bronchial arteries after early surgical repair of transposition of the great arteries by the arterial switch operation, and to report the results of catheter-directed therapy in five patients.

BACKGROUND

Pathologic and angiographic studies have demonstrated enlarged bronchial arteries in patients with transposition of the great arteries.

METHODS

A subjective 4-point scale was used to grade postoperative angiograms performed in 119 patients at our institution between January 1983 and December 1991. Grades 0 and 1 were designated if there was no opacification of the pulmonary arteries or veins, whereas grades 2 and 3 were assigned if there was such opacification. The median age at repair was 8 days (range 1 day to 13 months) and the median age at catheterization was 11.2 months (range 3.6 to 58.5). An intact ventricular septum was present in 84 (71%) of 119 patients.

RESULTS

Significantly increased bronchial flow (grade 2 or 3) was present in 55 (46%) of 119 patients. Age at repair, age at catheterization and interval between repair and catheterization were not associated with significantly increased bronchial flow; however, an intact ventricular septum was weakly associated with increased flow (p = 0.04). Coil embolization was performed in five patients with complete occlusion of the vessels and no significant complications.

CONCLUSIONS

Abnormally enlarged bronchial arteries are frequently identified at postoperative catheterization despite early repair and may explain continuous murmurs or persistent cardiomegaly in patients with otherwise normal noninvasive findings. When clinically indicated, catheter-directed therapy can be performed with good results.

Effect of baffle fenestration on outcome of the modified Fontan operation

BACKGROUND

The "fenestrated Fontan" (surgical baffle fenestration followed by transcatheter test occlusion and permanent closure after postoperative recovery) was adopted in an effort to reduce perioperative mortality and morbidity. This study assesses the effect of baffle fenestration on outcome.

METHODS AND RESULTS

Patients having a modified Fontan operation with a cavocaval baffle and cavopulmonary anastomosis were retrospectively selected for study. Those with baffle fenestration (n = 91) were compared with those without baffle fenestration (n = 56) with respect to preoperative risk factors, age, anatomy, surgical date, and presence or absence of a previous bidirectional cavopulmonary anastomosis. Outcome variables were failure (death or take-down) and duration of postoperative pleural effusions and hospitalization. Survival and clinical status after hospital discharge were ascertained. The two groups did not appear to differ with respect to age or anatomic diagnosis. Patients having baffle fenestration were at significantly greater preoperative risk by univariate and multivariate analysis (p < 0.01). Operative failure was low in both groups (11% without and 7% with baffle fenestration, p = NS). Durations of pleural effusions and hospitalization were significantly shorter with baffle fenestration (p < 0.01). Neither date of surgery nor a previous bidirectional cavopulmonary anastomosis appeared to contribute to improved outcome. Patients with baffle fenestration had lower postoperative systemic venous pressure (p < 0.01). There were no late deaths. Functional status in both groups is good (82% in New York Heart Association class I).

CONCLUSIONS

Baffle fenestration is associated with low mortality, significantly less pleural effusion, and significantly shorter hospitalization among high-risk patients having a modified Fontan operation.

Transcatheter umbrella closure of valvular and paravalvular leaks

OBJECTIVES

Our aim was to adapt the technique of transcatheter umbrella closure of intracardiac defects for closure of valvular and paravalvular defects.

BACKGROUND

The double-umbrella device developed by Rashkind and Cuaso has been safely and effectively delivered across a host of intracardiac defects, but transcatheter closure of valvular and paravalvular leaks has not been reported.

METHODS

Between February 1987 and September 1990, eight patients who were believed to be poor operative candidates were taken to the catheterization laboratory for transcatheter double-umbrella closure of a valvular or a paravalvular leak. Four patients had a paravalvular leak around a prosthetic aortic valve. The other four patients had a valvular leak: one patient with a regurgitant native aortic valve after a Stansel procedure and three patients with a regurgitant porcine valve in a left ventricular apex to descending aorta conduit.

RESULTS

Placement of a double-umbrella device was attempted in seven of the eight patients and was successful in all seven. Device placement was not attempted in one patient because of the crescentic shape of his defect. Two patients required two devices for each closure; the other five required only one device each. Angiography, performed on six patients after device closure, demonstrated that three patients had a completely occluded defect, two had trivial residual flow and one patient had mild residual flow through the device. All significant complications occurred in one patient who had hemolysis and oliguria that resolved when the initial umbrella was replaced by a larger device. In addition, two devices migrated to the patient's pulmonary arteries but were retrieved in the catheterization laboratory without difficulty. No other early or late complications occurred in 21 to 50 months of follow-up. Of the four patients with a paravalvular leak, the one who did not receive a device died at operation, one patient died at operation for an associated defect (in the operating room the umbrella was found securely in place across the paraaortic defect) and two patients are clinically well at home after 21 and 32 months, respectively. Of the four patients with closure of a valvular leak, one patient remains well at home 50 months later, one patient died at operation for associated defects and two patients had additional successful surgical treatment and remain well 29 months after device placement.

CONCLUSIONS

Transcatheter umbrella closure appears to be a reasonable alternative for closure of a valvular or paravalvular leak in patients who are poor operative candidates.

Surgical management of late right ventricular failure after Mustard or Senning repair

BACKGROUND

Information on surgical management and outcome in patients who develop symptomatic right ventricular failure after prior Mustard or Senning operations is limited.

METHODS AND RESULTS

From March 1987 to March 1991, 10 patients 3.6-23.5 years old (median, 7.0 years) with transposition of the great arteries and prior Mustard (six patients) or Senning (four patients) repairs (performed at ages 2 months to 5 years; median, 6 months) underwent surgical intervention for symptomatic right ventricular failure. In five of 10 patients, anatomic correction with either an arterial switch operation (three patients) or a pulmonary artery-to-aorta anastomosis and right ventricle-to-pulmonary artery conduit (two patients) was performed. Before anatomic correction in these five patients, four of five patients had a pulmonary artery band to prepare the left ventricle. The interval between preparation and correction ranged from 8 days to 12 months (median, 2 months). One patient died after an arterial switch operation. In the remaining five patients, coexisting left ventricular dysfunction precluded anatomic correction; all five patients survived cardiac transplantation. Survival for the entire group of 10 patients is 90%, and the median postoperative hospital stay was 17 days. During follow-up (12-62 months; median, 27 months), there were no deaths. Neoaortic insufficiency after anatomic correction was common (mild in one patient, moderate in two patients, and severe in one patient who required aortic valve replacement 4 months after surgery). In the transplantation group, one patient developed lymphoma 3 months after transplantation but is currently in remission after reduction of immunosuppression.

CONCLUSIONS

In patients who develop late right ventricular failure after Mustard or Senning repair, surgical intervention with either anatomic correction or cardiac transplantation can be done with acceptable morbidity and low mortality. Neoaortic valve insufficiency demands close follow-up after anatomic correction.

Front-loading of double-umbrella devices, a new technique for umbrella delivery for closing cardiovascular defects

In all, 22 defects (6 atrial septal, 13 ventricular septal, 2 patent ductus arteriosus and 1 coronary artery fistula) in 17 patients were closed with double umbrella using a new delivery technique, front-loading. The umbrella was loaded in the sheath outside the body and then advanced with-out use of the rigid pod to the defect. The defect was successfully closed in all 17 patients, including 5 in whom standard delivery techniques were unsuccessful. Front-loading enables the double umbrella to be delivered through a smaller long sheath than does the standard technique, and enables the flexible umbrella rather than the rigid pod to be advanced through curves in the sheath, and may improve delivery of double-umbrella devices to inaccessible parts of the circulation.

Transcatheter closure of coronary artery fistulas

Transcatheter closure of a coronary artery fistula was undertaken in nine patients. There were three fistulas from the left circumflex coronary artery to the coronary sinus, three from the left anterior descending coronary artery to the right ventricular apex, two from the right coronary artery to the superior vena cava/right atrial junction and one fistula from the left circumflex artery to the pulmonary artery. The fistula was closed with Gianturco coils in six patients, a double-umbrella device in two and a combination of an umbrella and coils in one patient. All fistulas are completely occluded. Complications consisted of migration of two coils, one of which was retrieved, and a transient junctional tachycardia in one patient. In an additional three patients with multiple coronary artery fistulas, transcatheter occlusion was not attempted.

Predictors of survival in neonates with critical aortic stenosis

BACKGROUND

Failure of infants with critical aortic stenosis to survive after adequate valvotomy despite a left ventricular size that appears to be adequate indicates that additional preoperative anatomic features may contribute to mortality.

METHODS AND RESULTS

Discriminant analysis was used to determine which of several echocardiographically measured left heart structures were independent predictors of survival after valvotomy for neonatal critical aortic stenosis. It was possible to predict outcome after classic valvotomy (two-ventricle-type repair) with 95% accuracy based on mitral valve area, long-axis dimension of the left ventricle relative to the long-axis dimension of the heart, diameter of the aortic root, and body surface area. Left ventricular volume was not a major determinant in this study, in part because patients who had initial valvotomy had been preselected in favor of an adequately sized left ventricle. Patients with multiple small left ventricular structures were found to have significantly improved survival after initial Norwood operation. In contrast, balloon valvotomy with subsequent Norwood procedure was usually unsuccessful.

CONCLUSIONS

The adverse effects of small inflow, outflow, and/or cavity size of the left ventricle are cumulative. The accuracy of prediction of outcome based only on preoperative anatomy indicates that adequacy of valvotomy is not generally a limiting factor for survival in this group of patients. It is possible to identify subjects whose chance of survival is better after a Norwood procedure rather than valvotomy, even if left ventricular volume is not critically small.

Transcatheter closure of a large patent ductus arteriosus with the clamshell septal umbrella

In 14 patients undergoing transcatheter closure of a large (greater than 4 mm diameter) patent ductus arteriosus, occlusion was attempted with use of the Bard Clamshell septal umbrella. Patient age ranged from 0.7 to 30.4 years. Isolated patent ductus arteriosus was present in 11 patients; 3 had additional congenital heart lesions. Moderate or severe pulmonary hypertension was present in four patients. The diameter of the patent ductus arteriosus ranged from 4.5 to 14 mm, as determined by contrast injection through an 11F sheath or by balloon sizing; it appeared larger by this method than by the standard angiographic method. All 14 patent ductus arteriosi were successfully closed. Prior embolization of a Rashkind umbrella was the reason for using a Clamshell device in three patients; one additional embolization of a Clamshell device occurred. All errant devices were retrieved at cardiac catheterization, without associated hemodynamic instability. No other complications occurred. Among the 14 patients, 11 had complete ductal closure by Doppler color flow mapping at last follow-up and 3 had trivial residual flow. All four patients having associated complex lesions or pulmonary hypertension, or both, had symptomatic improvement after the procedure, although one child (with Shone's anomaly) died 3 months later. The Clamshell device provides stable and effective closure of a large patent ductus arteriosus, and allows transcatheter closure to be offered to some patients who were previously considered unsuitable for this procedure.

Transesophageal echocardiography with color Doppler during interventional catheterization

Echocardiography has been used during interventional cardiac catheterization for guidance of the procedure and assessment of results. However, limited echocardiographic windows and logistical difficulties make conventional echocardiography during interventional catheterization impractical and of limited value. Transesophageal echocardiography (TEE) with Doppler color flow mapping is more useful than conventional echocardiography for guidance of interventional catheterizations. Device closure of congenital atrial and ventricular septal defects (ASDs and VSDs) and of postoperative residual interatrial and interventricular communications, balloon valvuloplasty, and Brockenbrough atrial septal puncture with ASD creation have been performed under combined fluoroscopic and TEE guidance. Transesophageal echocardiography can be performed continuously throughout the procedure, allowing simultaneous fluoroscopic and echocardiographic assessment of catheter position. Localization of individual device arms during transcatheter device closure of ASDs and VSDs is easier and more accurate when TEE is used, resulting in a lower incidence of incorrect device positioning. Doppler color flow mapping is used to determine number, location, and size of defects, to detect residual shunts after device closure, and to assess valve insufficiency after balloon valvuloplasty and other procedures. Combined TEE and fluoroscopic guidance of interventional procedures, with echocardiographic assessment of results, reduces the amount of radiation and contrast used during the procedure, allowing performance of additional interventional procedures during the same catheterization. Transesophageal echocardiography is indicated during interventional procedures in which simultaneous Doppler color flow mapping and precise localization of catheter, balloon and/or device position will result in a higher success rate and decreased morbidity.

Use of endovascular stents in congenital heart disease

BACKGROUND

Balloon expandable intravascular stents have been used to support vessel walls in coronary and peripheral arteries in adults. The purpose of this study was to examine the efficacy and safety of these stents in the treatment of congenital heart disease.

METHODS AND RESULTS

Forty-five stents were placed in 30 patients, who were 0.2-30.2 years old (weight, 3.5-76 kg). Patients with areas of stenosis that were difficult to approach surgically were chosen. Stents were mounted over balloons and placed by standard catheterization techniques. Twenty-three patients had branch pulmonary artery stenosis. Thirty-six stents were placed successfully and had reduced pressure gradients from 50.6 +/- 24 to 15.9 +/- 13.4 mm Hg. Five patients had stents placed after atrial surgery: three in obstructed Fontan repairs, one at the superior vena cava-right atrial junction after sinus venous defect repair, and one at the site of a Glenn shunt. Atrial stents reduced pressure gradients from 9.8 +/- 8.2 to 2.0 +/- 2.6 mm Hg. One patient had a stent placed in the descending aorta after coarctation dilation, and the pressure gradient was reduced from 50 to 25 mm Hg. One patient had pulmonary vein dilation with stent placement. Two stents migrated at the time of placement; one required surgical removal, and one was anchored in place by balloon dilation. One patient died within 24 hours of catheterization because of thrombus obstruction of the Fontan repair. Nine patients have undergone recatheterization. All stented vessels have remained at the same caliber as at original stent placement.

CONCLUSIONS

We conclude that balloon expandable stents are useful in selected postoperative stenoses in congenital heart disease.

Preoperative transcatheter closure of congenital muscular ventricular septal defects

BACKGROUND

Surgical repair of muscular ventricular septal defects, particularly those associated with complex heart lesions carries a higher risk of reoperation and death than the repair of membranous defects. Closing a muscular defect through an incision in the systemic ventricle may cause late ventricular dysfunction. In a collaborative approach to this problem, we undertook preoperative transcatheter closure of muscular ventricular septal defects remote from the atrioventricular and semilunar valves, followed by the surgical repair of associated conditions.

METHODS

In 12 patients selected jointly by a cardiologist and a cardiac surgeon, we attempted preoperative transcatheter umbrella closure of 21 defects. Half the patients had associated complex heart lesions; the others had had pulmonary-artery banding to reduce the amount of left-to-right shunting. Half had severe ventricular septal deficiency.

RESULTS

All 21 defects were successfully closed without major complications. Subsequent cardiac surgery for associated conditions in 11 of the 12 patients resulted in a mean pulmonary-to-systemic flow ratio of 1.1, indicating minimal residual left-to-right shunting; 1 patient awaited surgical repair. No deaths, reoperations, or late complications have occurred after a follow-up of 7 to 20 months.

CONCLUSIONS

A collaborative approach using transcatheter closure followed by the surgical repair of associated cardiac lesions may decrease rates of operative mortality, reoperation, and left ventricular dysfunction in patients with muscular ventricular septal defects.

Kinetics of the creatine kinase reaction in neonatal rabbit heart: an empirical analysis of the rate equation

Here we define the kinetics of the creatine kinase (CK) reaction in an intact mammalian heart containing the full range of CK isoenzymes. Previously derived kinetic constants [Schimerlik, M. I., & Cleland, W. W. (1973) J. Biol. Chem. 248, 8418-8423] were refit for the reaction occurring at 37 degrees C. Steady-state metabolite concentrations from 31P NMR and standard biochemical techniques were determined. 31P magnetization transfer data were obtained to determine unidirectional creatine kinase fluxes in hearts with differing total creatine contents and differing mitochondrial CK activities during KCl arrest and isovolumic work for both the forward reaction (MgATP synthesis) and reverse reaction (phosphocreatine synthesis). The NMR kinetic data and substrate concentration data were used in conjunction with a kinetic model based on MM-CK in solution to determine the applicability of the solution-based kinetic models to the CK kinetics of the intact heart. Our results indicated that no single set of rate equation constants could describe both the KCl-arrested and working hearts. We used our experimental data to constrain the solution-derived kinetic model and derived a second set of rate equation constants, which describe the isovolumic work state. Analysis of our results indicates that the CK reaction is rate limited in the direction of ATP synthesis, the size of the guanidino substrate pool drives the measured CK flux in the intact heart, and during isovolumic work the CK reaction operates under saturating conditions; that is, the substrate concentrations are at least 2-fold greater than the Km or Kim for each substrate.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of 23Na NMR spectra from isolated perfused hearts

The 23Na NMR spectra obtained from isolated hearts perfused with buffer containing the paramagnetic shift reagent dysprosium triethylenetetraminehexaacetic acid, Dy(TTHA)3-, are complex and contain a number of overlapping peaks of different intensities. Spectra from rat, rabbit, guinea pig, and ferret hearts obtained during periods of control perfusion are similar and undergo similar changes when the hearts are subjected to periods of ischemia and reflow. The contributions from the intracellular, interstitial, vascular, and bath compartments to the multiple peaks in the spectra of rats hearts have been assigned. The significant contributions to these spectra of bulk magnetic susceptibility effects and incomplete mixing have been demonstrated through a series of modeling experiments. Since the spectra from hearts of different species are so similar, the peak assignments made for the rat are applicable to spectra from rabbit, guinea pig, and ferret hearts as well. This work provides a framework for quantitative analysis of the spectral changes which occur during conditions such as ischemia and reflow.

Double-umbrella closure of atrial defects. Initial clinical applications

Forty patients were catheterized for closure of atrial septal defects with the Rashkind patent ductus arteriosus umbrella device, a modified Rashkind umbrella device, and the newly designed Lock Clamshell Occluder. Patients weighed 8 kg or more (a requirement for transvenous access with the 11F delivery sheath) and had defects suitable for closure based on two-dimensional echocardiography. The new device was at least 1.6 times the diameter of the atrial septal defect as determined by balloon sizing at catheterization. Patients were followed up by telephone, clinical examination, and echocardiography at 6 months. We attempted closure in 34 patients, with atrial septal defects ranging in diameter from 3 to 22 mm; device sizes ranged from 17 to 33 mm. Initial device position immediately after release was correct in all patients. A cerebral embolus occurred in one elderly patient before device placement--the patient died 1 week later. Two instances of early device embolization occurred, and devices were retrieved by catheter without complication. Follow-up of 31 patients discharged with devices in place, for a total of 31 patient-years, has yielded no umbrella-related complications. Adequate imaging studies in 19 patients 6.5 months after device placement revealed no atrial shunt in 12; residual flow through separate, previously unrecognized atrial septal defects occurred in two; and small residual leaks (less than 3 mm) around devices were present in five patients. This initial success indicates that double-umbrella closure of atrial septal defects will aid in the treatment of intracardiac defects.

Early results and follow-up of balloon angioplasty for branch pulmonary artery stenoses

Two hundred eighteen balloon angioplasty procedures were performed in 135 patients with branch pulmonary artery stenoses from June 1984 to February 1989. Arteries were dilated in patients with tetralogy of Fallot (n = 49), tetralogy of Fallot/pulmonary atresia (n = 64), isolated peripheral pulmonary artery stenoses (n = 58) and "other" lesions (the majority had truncus arteriosus or single ventricle and surgically induced pulmonary artery stenoses (n = 47). Mean age at dilation was 6.6 +/- 6.3 years (range 1 month to 38.5 years). The mean diameter of the lesion increased from 3.8 +/- 1.7 to 5.5 +/- 2.1 mm with dilation (p = 0.001). The overall success rate was 58% (127 of 218 dilations), assessed by the following criteria: an increase greater than or equal to 50% of predilation diameter, an increase greater than 20% in flow to the affected lung or a decrease greater than 20% in systolic right ventricular to aortic pressure ratio. Success did not correlate with patient age. Mean balloon to artery ratio was higher in successful (4.2) than in failed (3.0) angioplasty procedures (p = 0.0001). There were four early deaths: two of the patients had pulmonary artery rupture with angioplasty performed less than 1 month after pulmonary artery surgery. An aneurysm occurred in 11 arteries and transient pulmonary edema in four patients. At angiography performed a mean of 10 months (range 1 to 54) after dilation, the mean diameter of 57 arteries was unchanged (5.5 versus 5.4 mm). However, 5 of 32 initially successfully dilated vessels had returned to predilation size as a result of restenosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Balloon dilation of branch pulmonary artery stenosis

We consider balloon angioplasty to be an established, highly useful procedure in the management of branch pulmonary artery stenosis. It is successful in approximately 60% of cases. Current figures would indicate a low but significant mortality rate (1%) and a risk of aneurym formation (3%). Patients undergoing balloon angioplasty in the acute postpulmonary artery surgical period constitute a particularly high risk group for vessel rupture. Restenosis after branch pulmonary dilation is infrequent, but does occur. Further improvements in the use of this procedure should probably involve the use of expandable intravascular stents for patients with failed dilations or evidence of restenosis.

Neonatal critical valvar aortic stenosis. A comparison of surgical and balloon dilation therapy

Balloon aortic valvotomy (BAV) is an alternative to surgical valvotomy in infants and children. We compared BAV in 16 consecutive neonates (1985-1988) to surgical valvotomy in a prior group of 16 consecutive neonates (1978-1984). Both groups were comparable in terms of age, weight, hemodynamic data, left ventricular size, and associated lesions. There were six early and one late deaths after surgery. Five out of six neonates requiring a second operation died. Left ventricular size (measured in 13 neonates) had some influence on survival after surgery: three of three with small or hypoplastic left ventricles and three of 10 with normal-sized left ventricles died. After BAV, there were three early deaths, two patients who underwent stage I palliation of hypoplastic left heart syndrome, and two late deaths. As with surgical valvotomy, left ventricular size seemed to influence survival after BAV: five of six with small or hypoplastic left ventricles died or underwent stage I palliation for hypoplastic left heart syndrome and two of nine with normal-sized left ventricles died. At follow-up (26 +/- 17 months) in six patients in the surgical group, the peak systolic ejection gradient (PSEG) was 52.2 +/- 23 mm Hg and left ventricular end-diastolic pressure (LVEDP) 18.2 +/- 5.2 mm Hg. Aortic regurgitation was mild in five and moderate in the sixth patient. At follow-up (17.6 +/- 7.8 months) in nine patients in the balloon dilation group, the PSEG was 45.6 +/- 11 mm Hg in five patients at catheterization and 43.8 +/- 22.9 mm Hg in four patients by echocardiography-Doppler. Aortic regurgitation was mild in three and absent in the other six patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Balloon dilation of postoperative right ventricular outflow obstructions

Balloon dilation was attempted in 16 patients, aged 5 months to 19.5 years, with right ventricular outflow obstruction after repair of congenital heart defects. Stenosis of a valved conduit between the pulmonary ventricle and pulmonary artery was present in nine patients with a mean transvalvular peak systolic ejection gradient of 61.6 +/- 21.0 mm Hg and a mean right ventricle to aorta pressure ratio of 0.9 +/- 0.2. Supravalvular pulmonary stenosis was present in seven patients; in five, stenosis was at the anastomotic site after the arterial switch operation with a mean peak systolic ejection gradient of 72.2 +/- 10.6 mm Hg and mean right ventricle to aorta pressure ratio of 0.93 +/- 0.05. The other two patients had stenosis at a previous pulmonary artery band site with a peak systolic ejection gradient of 60 and 65 mm Hg and right ventricle to aorta pressure ratio of 0.75 and 0.72, respectively. Balloon dilation was successful in three of nine patients with a valved conduit; two of them had additional successful balloon dilation of the right pulmonary artery. In five of the nine patients (including one with successful dilation) the conduit was replaced 5.7 +/- 4.5 months after balloon dilation. Balloon dilation was successful in only one of the five patients with supravalvular pulmonary stenosis after the arterial switch operation and partially successful in the two patients with supravalvular pulmonary stenosis at a previous band site. The success rate of balloon dilation of postoperative right ventricular outflow obstruction is much lower than that for other right heart obstructions.

Transcatheter closure of atrial septal defects. Experimental studies

Recent experience with the spring-loaded patent ductus arteriosus (PDA) occluder has demonstrated several advantages of this device in the closure of intracardiac defects compared with previously described techniques. Pathologic and animal model studies were performed to identify which atrial septal defects (ASDs) might be suitable for device closure and to test a new septal closure double umbrella. Fifty specimens from the Cardiac Registry with unrepaired ASD secunda (2 degrees) were analyzed. Mean ASD size was 8 x 10 mm (range, 3 x 4 to 30 x 30 mm); 80% (n = 40) of ASDs were judged closable with the new device. ASD closure was attempted in four lambs with the Rashkind (hooked single umbrella) ASD occluder. One of four umbrellas was correctly positioned; no ASDs were closed. A new double-hinged ("clamshell") umbrella device was designed: eight ASD closures were attempted with this device (defects ranged from 8 to 20 mm in diameter). Six of eight umbrellas were correctly positioned; four of four animals observed more than 1 day appeared to have complete closure on postmortem examination with endothelialization of the device. We conclude that 1) most ASD 2 degrees are far enough from vital structures to permit closure, 2) initial placement of hooked umbrellas is often incorrect and cannot be altered, 3) clamshell double umbrellas were successfully placed in six of eight attempts, and 4) endothelialization of closed ASDs appears complete within weeks of implantation. These preliminary studies appear promising and support testing the clamshell ASD device in clinical trials.

Interventional catheterization of left heart lesions, including aortic and mitral valve stenosis and coarctation of the aorta

The current status of percutaneous balloon valvotomy for aortic, subaortic, and mitral stenosis and angioplasty of aortic arch obstructions are reviewed. Results from the authors and other laboratories are discussed in relation to technique and other factors such as patient age and underlying pathology. Current indications for these procedures are reviewed.

Coil embolization to occlude aortopulmonary collateral vessels and shunts in patients with congenital heart disease

Gianturco coils were used to embolize 77 vessels in 54 patients: 58 aortopulmonary collateral vessels, 14 Blalock-Taussig shunts, 3 arteries involved in pulmonary sequestrations and 2 venae cavae. Embolization resulted in total occlusion in 53 (69%), subtotal occlusion in 19 (25%) and partial occlusion in 3 (1 intentional). Two embolizations failed to reduce flow. Thus, 72 (95%) of 76 embolizations in which complete occlusion was the intended result resulted in total or subtotal occlusion. Analysis of the results demonstrates that completely occluded collateral vessels were longer and had a smaller diameter than did incompletely occluded vessels. Complications included six cases of inadvertent embolization to the pulmonary arteries (n = 5) or the aorta (n = 1); three were retrieved and three were left without symptoms. In addition, there was a case of severe hemolysis after intentional partial occlusion of a Blalock-Taussig shunt. The results demonstrate that coil embolization can be an effective procedure for managing a wide variety of aorto-pulmonary collateral vessels and shunts in children with congenital heart disease.

Interventional cardiac procedures in neonates and infants: state of the art

The currently available interventional cardiac procedures in neonates and infants are at various stages of development. We currently dilate neonates and infants with critical valvular pulmonary and aortic stenosis and postoperative aortic obstruction. We do not routinely dilate native coarctation of the aorta because of the possibility of aneurysm formation, unless the neonate is very sick and acidotic and an operative approach is considered to be high risk. Balloon and blade atrial septostomy are done routinely whenever indicated with a low incidence of morbidity. Coil embolization, endomyocardial biopsy, foreign body retrieval and percutaneous pericardial drainage are relatively safe, and with the currently available instruments these techniques can be performed safely in neonates and infants with the same indications as for older patients. We currently consider stenotic pulmonary veins to be an undilatable lesion and an optimal therapy remains to be defined. Transcatheter closure of PDA and intracardiac shunts is presently limited to older patients, due to the large size of the delivery system devices and cannot currently be used in neonates. Dilation of the pulmonary valve in cyanotic congenital heart disease appears useful, but further experience is needed.

Balloon dilation of congenital aortic valve stenosis. Results and influence of technical and morphological features on outcome

We evaluated dilation technique (n = 80) and aortic valve morphology by two-dimensional echocardiography (n = 58) in patients with congenital aortic valve stenosis to determine their influence on outcome. Patients' age (9 +/- 9 years; range, 1 day-39 years) and a history of surgical valvotomy did not influence outcome. The number of dilating balloons (one vs. two) and balloon: annulus ratio based on the largest balloon used in each case (97 +/- 12%; range, 71-133%) did not demonstrably influence the percent reduction in valvar gradient. In contrast, with a balloon: annulus ratio greater than 100%, the incidence (26%) of significant, dilation-induced aortic regurgitation was higher than occurred when the ratio was equal to or less than 100% (11%). Fifty bicommissural and eight unicommissural valves were identified echocardiographically. Relief of obstruction was associated with apparent commissural division in 24 of 32 patients with suitable postdilation studies. The sites of fusion and stenosis relief did not influence percent reduction in valvar gradient. Substantial increases in aortic regurgitation (greater than three of five grades) occurred in three of eight unicommissural and one of 50 bicommissural valves. The presence of a thick valve was associated with a slightly lower gradient reduction (53 +/- 12%) than thin and pliant valves (63 +/- 24%) (p greater than 0.05). Unlike all other congenital lesions we have studied, dilation technique and balloon size appeared to have a lesser influence on percent reduction in valvar gradient in congenital aortic stenosis, although balloon: annulus ratio influences the increase in aortic regurgitation. Valve morphology appears to assist with predicting the outcome of dilation.

Velocity of the creatine kinase reaction decreases in postischemic myocardium: a 31P-NMR magnetization transfer study of the isolated ferret heart

Recovery of postischemic function may be limited by energy synthesis by mitochondria, energy transfer via the creatine kinase reaction, or energy utilization at myofibrils. To identify the limiting step, we defined the relations among oxygen consumption, creatine kinase reaction velocity and cardiac performance in myocardium reperfused following mild, moderate, and severe ischemia. Isolated isovolumic ferret hearts were perfused with Krebs-Henseleit buffer at 37 degrees C. After 30 minutes of control, hearts were made ischemic for 20, 40, or 60 minutes and reperfused for 40 minutes. During preischemia, cardiac performance (estimated as the rate-pressure product), was 14.8 x 10(3) mm Hg/min, oxygen consumption was 16.7 mumol/min/g dry weight, and creatine kinase reaction velocity measured by 31P-nuclear magnetic resonance saturation transfer was 12.7 mM/sec. For hearts reperfused after 20, 40, or 60 minutes of ischemia, rate-pressure product was 11.5, 6.5, and 1.1 x 10(3) mm Hg/min; oxygen consumption was 13.5, 14.2, and 6.9 mumol/min/g dry weight; and creatine kinase reaction velocity was 9.6, 5.0, and 2.0 mM/sec, respectively. Thus, with increasing severity of insult, creatine kinase reaction velocity decreased monotonically with performance (r = 0.99). Changes in creatine kinase reaction velocity were predicted from the creatine kinase rate equation (r = 0.99; predicted vs. measured velocity) and can therefore be explained by changes in substrate concentration. Oxygen consumption did not correlate with performance or creatine kinase velocity, consistent with abnormalities in mitochondrial energy production. In all cases, creatine kinase reaction velocity was an order of magnitude faster than the maximal rate of ATP synthesis estimated by oxygen consumption. We conclude that, in postischemic myocardium, creatine kinase reaction velocity decreases in proportion to performance, but high-energy phosphate transfer does not limit availability of high-energy phosphate for contraction.