Complications associated with pediatric cardiac catheterization

Methods

Results

Risk factors

The only independent risk factors for any complication included the year of the catheterization, the type of procedure and the age of the patient. The age of the patient and the year of catheterization were categorized and reentered into a multiple logistic regression model (Table 4). After controlling for age and type of procedure, the highest risk occurred in 1993 with a nadir in 1989 and 1990. Relative to 5-to-9 year olds, the independent risk of complications was greatest up to 2 years of age. Relative to diagnostic procedures, interventional catheterizations were independently associated with a greater risk of complication.

Independent risk factors associated with the presence of a major complication included patient weight, type of procedure and if the patient was a hospital inpatient at the time of the procedure (Table 5). After categorizing patient weight, the risk of a major complication was significantly greater, relative to the 20 kg to <40 kg patient group, for patients who were <10 kg at the time of the procedure. Risk was independently reduced if the patient was an outpatient at the time of the procedure and for INTV catheterizations.

Risk factors for arterial complications were sought in the matched case-control study. There were no significant differences between the ages and dates of procedures for the 50 cases and the 50 matched controls in assessment of risk factors for arterial complications. Three of the cases did not have arterial catheters or sheaths placed at catheterization, but the artery was entered briefly during attempts to enter the vein. The catheterization was for diagnostic purposes for 56% of cases and 68% of controls (p = ns), and 56% of patients in both groups had had a previous catheterization. There were no differences between matched cases and controls regarding height, weight, body surface area, systemic arterial oxygen saturation, duration of procedure, fluoroscopy time or the amount of radiographic dye used per kilogram of patient weight. There was a trend (p = 0.06) toward decreased hemoglobin concentrations in the cases. While there was no significant difference regarding the amount of heparin bolus given per kilogram, cases had lower doses when adjusted for the duration of the procedure. Cases also had larger arterial sheaths or catheters when French size was adjusted for the body surface area of the patient.

Discussion

Throughout the nearly 50 years since the landmark works reporting cardiac catheterization in children (19,20), technical improvements have allowed the performance of invasive procedures reliably and safely, even in the youngest and smallest of patients (2,12). Yet adverse events during such procedures have not been completely eliminated. This is particularly true with the expansion of the cardiac catheterization from a primary anatomic–hemodynamic investigation to include therapeutic interventions (1,3,5,6,11,21–23). In addressing these complications, few reports detail the full spectrum related to cardiac catheterization procedures in childhood (4), either exclusively addressing interventional studies (3,5), reviewing only relatively small numbers (4)or including an adult population (3). This contemporary prospective study addresses all complications occurring during cardiac catheterization studies performed in a large tertiary care pediatric teaching cardiac unit by multiple operators. Thus, this review summarizes risk as it applies not only to the special skills of the interventional cardiologist, but those experienced by staff physicians and trainees performing general diagnostic studies. From a population of 4,952 patients, 560 complications were identified in 436 cases representing 102 major and 458 minor events. This incidence is similar to earlier reports (4)but less than that noted in older reviews (6,7)or studies addressing exclusively interventional catheterizations (3,5).

Although death occurred in 0.14% of patients, the Cooperative Study on Cardiac Catheterization (8)conducted between 1963 and 1965 found a mortality of 0.44% from 12,364 studies performed from the newborn period through adulthood, the highest mortality (6.0%) in the first 2 months of life and lowest (0.14%) over 2 years of age. A similar study conducted on a pediatric population (1,859 patients, age range: 1 day to 15 years) between 1964 and 1970 found an overall mortality of 1.5% (7), and between 1965 and 1967 from the University of California, San Francisco (6)a reported mortality of 0.26% was observed, or 3.1% if all deaths within 24 h were considered. This same group recently reviewed their more current experience and found death complicating 0.19% of 1,037 cases performed between 1986 and 1988, or a mortality rate of 0.39% if all deaths within 24 h were included (4). All reviews note that mortality is influenced by age, being significantly higher in patients <1 year and particularly high in newborns, reflected by our experience and that from the New England Regional Infant Cardiac Program where a mortality of 3.8% (9)was noted. Despite these reports, a true mortality rate for pediatric catheterization is difficult to determine from the literature due to the various criteria used for collecting population data. Although most authors included patients dying within 24 h (4,6,7,10), some comment only upon those deaths directly related to the procedure (4,6), or include only diagnostic cases (6,7,10), interventional studies (4)or exclusively therapeutic catheterizations (3,5). Additionally, while some reports consider pediatric populations (4,5–7), others include adults (3,8,24)or report only infants (9)or neonates (10,25). Nevertheless, some inferences can be drawn from our data and that of the literature. First, there is a decreasing risk of mortality over the last decade, from 1.5 to 3.0% in earlier reviews (6,7)to 0.14% in our experience. Indeed, a study from this institution 20 years ago (26)noted a mortality rate in newborns (within 24 h of the procedure) of 6.7% and an overall incidence of death of 0.96%. This reduction in mortality relates to fewer procedures being required in infants and newborns where anatomic information to guide management can be obtained through alternative, noninvasive means (27–29)or supplements noninvasive information, to improvement in care for the critically ill child, improvement in catheters and other support equipment (such as effective temperature control) and to the introduction of prostaglandin E₁. Complications related to catheter manipulation were the most common causes of death (57%) in our series, underscoring the need for diligent technique in small patients and correction of any abnormal metabolic parameter in the critically ill infant.

The overall incidence of arterial complications was 3.7%, and 7.3% in those <1 year of age, infrequently evolving into a major complication, although in 1 child a 2-cm leg length discrepancy developed (30–33). Avoiding arterial entry with the use of alternative techniques to enter the left heart (34)can avoid this complication. To this end, we have approached such arterial compromise with an aggressive management strategy after the procedure (16). Nevertheless, the true incidence of arterial compromise is unknown, underscored by the recent observations of Kocis et al. (34), who used Doppler ultrasonography to examine arterial pulse flow after arterial cannulation. These authors found a higher incidence of flow compromise (32%) than that clinically suspected. There is unfortunately little information to help predict how and when a reduced pulse may result in delay in limb growth, and studies to define this incidence and risk are badly needed. The INTV studies were an independent risk factor for arterial complications, but progress in reducing balloon and sheath sizes can, and to some degree has, reduced the incidence of arterial injury (14,15). Age was an additional independent risk factor, with 60% of such complications in our population occurring in infancy.

Arrhythmias were the next most common complication, with an incidence of 2.6% of the total studies, and the most common cause of a major complication. This incidence is less than that reported by other authors (4,6), although the discrepancy may in part be related to different criteria for inclusion (6,7). Among the 16 patients with either bradycardia or complete heart block as a major complication, 8 were <3 months of age. To prevent serious arrhythmias, judicious catheter manipulation and correction of any metabolic abnormality is critical, but being prepared for such events is vital.

The INTV procedures were more often associated with cardiac perforations, related in some degree to the complex nature of the procedures, small age and size of the patients and large, stiff catheters. However, atrial wall perforation during attempted transseptal puncture was well tolerated without the need for further intervention after withdrawal if recognized before the long sheath-dilator was advanced (35).

Complications related to INTV procedures have been previously reported in the literature (1,3,17,23). Embolization of implantable intravascular devices occurred in 19 procedures, with a major complication occurring twice for ductal occlusion in the years 1987 to 1988 and once for atrial septal defect occlusion in 1990; all occurred during the first applications of these devices (36). However, implanting a double umbrella device into the patent ductus arteriosus in infancy carries a high risk for flow compromise to the left pulmonary artery when the child is <10 kg (17). The majority of these events, however, have been defined months to years after implantation (37). Only those few (n = 2) in whom flow compromise was manifest during the procedure were included in the study. The so-called learning curve of a newly introduced INTV procedure similarly impacts the complication rates. However, as more INTV cardiologists are trained, it is anticipated that the introduction of any new technique will be rapidly brought into common application (38).