Author + information
- Received October 28, 1997
- Revision received June 25, 1998
- Accepted July 15, 1998
- Published online November 1, 1998.
- Renato Vitiello, MDa,
- Brian W McCrindle, MD, FRCP(C), FACCa,
- David Nykanen, MD, FRCP(C)a,
- Robert M Freedom, MD, FRCP(C), FACCa and
- Lee N Benson, MD, FRCP(C), FACCa,* ()
- ↵*Address for correspondence: Dr. Lee Benson, The Hospital for Sick Children, 555 University Avenue, Toronto, Ontario, Canada M5G 1X8
Objectives. The aim of this study was to determine the relative risks of pediatric diagnostic, interventional and electrophysiologic catheterizations.
Background. The role of the pediatric catheterization laboratory has evolved in the last decade as a therapeutic modality, although remaining an important tool for anatomic and hemodynamic diagnosis.
Methods. A study of 4,952 consecutive pediatric catheterization procedures was undertaken.
Results. Patient ages ranged from 1 day to 20 years (median 2.9 years). One or more complications occurred in 436 studies (8.8%) and were classified as major in 102 and minor in 458, with vascular complications (n = 189; 3.8% of procedures) the most common adverse event. Arrhythmic complications (n = 24) were the most common major complication. Death occurred in seven cases (0.14%) as a direct complication of the procedure and was more common in infants (n = 5). Independent risk factors for complications included a young patient age and undergoing an interventional procedure.
Conclusions. Complications continue to be associated with pediatric cardiac catheterization. Efforts should be directed to improving equipment for flexibility and size, and finding alternative methods for vascular access. Patient age and interventional studies are risk factors for morbidity and mortality.
Over the last decade, the pediatric catheterization laboratory, while continuing to play a significant role in anatomic and hemodynamic diagnosis, has evolved a therapeutic function (1,2). All such procedures, both diagnostic and interventional, are associated with some risk. To this end, a number of studies have addressed the risk of each form of invasive study (3–10), but were retrospective or reviewed relatively small patient numbers. To achieve an understanding of the relative risks of all such procedures, a prospective 7-year study was undertaken to determine the incidence of adverse events and predisposing factors associated with pediatric interventional and diagnostic cardiac catheterization.
During the period January 1, 1987, through December 31, 1993, all patients undergoing cardiac catheterization at The Hospital for Sick Children, Toronto, Ontario, Canada, had documentation of any adverse event on a case report form. During that period, 4,952 cardiac catheterizations were performed at a median age of 2.9 years (range, 1 day to 20 years), with 55% being males and 45% being females.
Data collection and study design
Procedures were classified as diagnostic (DGN), interventional (INTV) or electrophysiologic (EP). The INTV studies included all procedures where an attempted catheter therapy (e.g., septostomy, angioplasty, device implantation, embolization) occurred. The EP studies were defined as those procedures performed primarily to evaluate an arrhythmic problem. All other studies addressing anatomic or hemodynamic issues (including endomyocardial biopsy) were classified as DGN. A few patients were classified in two categories if each component was required for patient management. Records were maintained for complications related to the procedure. Complications were divided into major and minor. Major complications included all events leading to one of the following: a) death; b) life-threatening hemodynamic decompensation requiring immediate therapy (e.g., cardiac arrest, severe hypotension); c) the need for surgical intervention (e.g., removal of an embolized implanted device); or d) a significant unanticipated permanent anatomic or functional lesion resulting from the catheterization (e.g., cerebral infarct, permanent arterial thrombosis, vessel tear or aneurysm). Minor complications were defined as unanticipated events that were transient and resolved with specific treatment (e.g., transient arterial thrombosis or tolerated transient arrhythmic episode). Furthermore, in addition to the above event characterizations, episodes were categorized as vascular related (e.g., vessel thrombosis, aneurysms, etc.), bleeding, arrhythmias, deaths, events related to INTV procedures (e.g., device embolization), catheter manipulations (e.g., cardiac perforation, balloon rupture) and a miscellaneous grouping. If a complication was recorded, the patient hospital and cardiac records were reviewed to determine the treatment and the effect of the event on the patient’s course.
To define predictors of arterial complications a nested case-control study was undertaken. From those patients noted to have arterial complications, 50 patients were randomly selected and matched by age and date of catheterization to a control patient who had no arterial complication. Detailed information related to possible predictor variables such as patient weight, height and body surface area, hemoglobin concentration, systemic arterial oxygen saturation, size of the largest arterial catheter or sheath, duration of the procedure, fluoroscopy time, bolus dose of heparin sulfate administered and the amount of radiographic dye used were compared between the two groups.
Diagnostic and therapeutic procedures were performed according to previously described techniques (2,7,11,12). Patients for elective studies were generally admitted to the hospital the day of the procedure. General anesthesia was used for all INTV-EP procedures (13). Heparin sulfate (150 IU/kg) was administered intravenously after any peripheral arterial access and repeated after 2 h (75 IU/kg). Cineangiography was performed using a nonionic contrast agent (Isovue 300, Squibb Diagnostics, Montreal, Canada) at a dose of 0.5 to 2.0 ml/kg, average total dose per case, 4 ml/kg.
Descriptive statistics for the total population and all complications were obtained and included frequencies, medians with ranges and means with standard deviations. Independent risk factors for any complication and for any major complication were sought using stepwise multiple logistic regression analysis. Factors that were tested included patient age, weight and gender, and the year and type of catheterization procedure. The stepwise logistic regression was performed using SAS Institute Software (Version 6.12, Cary, North Carolina). A p value of <0.10 was used for selection for entry into the model, with a p value of <0.05 necessary for retention. Categories of categorical variables were entered as dummy variables into the model, with one category excluded as a reference variable. When a categorical variable was entered into the model, all categories were required to be present in the model for retention. Only a limited number of candidate variables were selected for testing in the model, that is, those with bivariate p values of <0.25. Significant continuously measured variables were categorized to determine the nature of the linear relationship with the defined outcome. Hosmer–Lemeshow goodness-of-fit testing was used to test the final models. To determine risk factors for arterial complications, cases and controls (see above) were compared using paired ttests and signed rank tests. The level of statistical significance was set at p < 0.05.
Among the 4,952 catheterizations, 1,081 procedures (22%) were performed with discharge the day of the study. In 1987, 12% were outpatient procedures; in 1993, 34% were performed in this format. In 964 cases (19% of the total catheterizations) patients were <6 months of age. There were 3,149 DGN, 1,371 INTV (45 had 2 INTV procedures), 383 EP and 41 INTV-EP catheterizations. The INTV studies represented 29% of the total number of catheterizations throughout the study period, increasing in number from 14% in 1987 to 43% in 1993, while EP studies represented 9% of the total number of cardiac catheterizations. One or more complications occurred in 436 (8.8%) procedures at a median patient age of 1.1 years, with a maximum number of complicated catheterizations in 1993 (n = 98, 13%) and a minimum in 1989 (n = 38, 5.4%). Adverse events were more likely to occur in younger patients. In 964 catheterizations on infants <6 months, 1 or more complications occurred in 135 cases, an incidence of 14%, the highest of all age groups, reported in 70 of 632 DGN studies and 65 of 322 INTV studies. Complications were significantly less likely in patients >10 years of age, and occurred in only 45 cases (Mantel–Hantzel chi-square, p < 0.01). One hundred and two major complications occurred during 74 procedures at a median patient age of 0.6 years (range, 1 day to 17 years), and 458 minor complications in 385 procedures at a median age of 1.3 years (range, 1 day to 18 years). The most common major complication was an arrhythmia (n = 24), while vascular complications had the highest incidence among minor adverse events (n = 189).
Complication by category (see Table 1)
Seven patient deaths were directly related to the catheterization (Table 2). All were critically ill, requiring ventilatory support prior to their study. Of 465 procedures involving neonates (<30 days of age), 4 catheterization-related deaths occurred (0.9%), significantly (p < 0.01) more frequent than in older patients. No deaths were reported in patients >5 years of age.
Rhythm disturbances occurred in 128 cases (2.6% of all cases) and included 24 major events. The most common arrhythmic event was atrioventricular block. Complete atrioventricular block occurred in 20 cases; 5 patients required pacing during the procedure, with recovery of sinus rhythm prior to discharge in all. First or second degree atrioventricular block was well tolerated at all ages and uniformly resolved. Supraventricular tachycardia complicated catheterization in 25 cases, but never progressed to a major adverse event, although in 9 cases cardioversion was required. When complete bundle branch block occurred it generally resolved shortly after the procedure, persisting in only one patient. ST-segment elevation was always a transient event, four episodes being related to entry into the left atrium through a long sheath during an INTV-EP study. Ventricular tachycardia or fibrillation occurred in 8 cases each, 4 patients being <6 months of age. Cardiopulmonary resuscitation was required in 12 patients, 4 of whom died in the laboratory.
An arterial thrombosis, with either a decreased or absent pulse, was present at the end of 165 cases, with restoration of patency in 153 cases. An INTV procedure was responsible for arterial thrombosis in 71 (43%) cases, with aortic valve dilation or coarctation/recoarctation angioplasty being the most common procedures performed (14,15). In the majority of the cases a continuous infusion of heparin sulfate, adjusted to a partial thromboplastin time of 80 to 120 s, was sufficient to regain vessel patency within 24 to 48 h (16). In 57 instances, a thrombolytic agent (streptokinase or tissue thromboplastin activator) was required for restoration of the pulse, had it not occurred with heparin sulfate (16). Surgical thrombectomy was required in two cases, with improved perfusion in both, although the limb pulse remained weak in one. Arterial thrombosis was permanent in 9 patients, occurring at a median age of 105 days of age (range: 70 days to 1.6 years). One patient with an absent pulse died before resolution could be ascertained.
This was a problem in only five cases. The most significant, and dramatic, occurred in a 6-month-old who had undergone aortic valvotomy. Retroperitoneal bleeding from a tear in the iliac artery resulted in acute and severe hypotension prompting surgical repair. Two additional patients required blood transfusions for blood loss during their procedures. Local bleeding (hematoma) was noted at the groin in 25 cases and in the mediastinum in 2 cases (1 each from the left subclavian artery which had been cannulated, and the superior vena cava, after stent implantation). None of these patients required blood transfusion.
Complications related to catheter manipulations
There were 10 major complications, including 5 cardiac perforations with cardiac tamponade, all occurring during INTV procedures. A pericardiocentesis (n = 4) or surgical repair was performed. Among other minor complications, myocardial stains during angiography were the most frequent (n = 19) but never evolved to a major adverse event.
Complications related to INTV procedures
During the period of study there were 1,457 interventional procedures (INTV and INTV-EP) performed during 1,412 catheterizations (Table 3). Complications were significantly more common in these studies, occurring in 13% of patients. The incidence of complications (of any kind) during INTV studies was not constant during the period of study, however, being 23% of INTV cases in 1987, declining to 10% in 1990, but increasing to 18% in 1993. In 3.2% of the interventional procedures (n = 46) major complications occurred, while in 10% (n = 145) there were minor complications. However, only 11 major and 40 minor complications were directly related to the intervention itself (Table 1). Balloon aortic dilation had the highest incidence of complications (42%), followed by dilation of Fallot’s tetralogy (40%) and recoarctation angioplasty (30%). Low-risk procedures included occlusion of the persistent arterial duct (5%) and pericardiocentesis (3%). Three patients had embolization of an occluder device, requiring surgical removal. One patient had significant hemolysis also requiring surgical removal 4 days after implant (17). Aortopulmonary shunt thrombosis occurred in one patient, requiring thrombolysis, and three patients undergoing aortic balloon dilation developed severe aortic insufficiency and were taken electively for surgical repair, with only mild insufficiency postoperatively. Embolization or malpositioning of an implantable device occurred as a minor adverse event, with devices retrieved in the laboratory (n = 8) or left in place without hemodynamic consequences (n = 7). The embolized devices included coils in six instances, six ductal umbrella occluders, one atrial defect occluder and two endovascular stents. Devices left in place included one ductal umbrella, one stent and five coils.
Infection as a minor adverse event was localized to the catheter entry site in two patients and systemically in two others, all requiring intravenous antibiotics. A drug reaction occurred in 13 cases, but in only 1 patient was it a major complication when the patient developed hypotension after administration of protamine sulfate. Respiratory problems, including respiratory distress or hypoventilation (n = 10) or hypercyanotic spells (n = 8), evolved into a major complication in only one case, where the patient developed pulmonary edema requiring treatment. No major complications were related to general anesthesia, although mild self-limiting stridor shortly after a procedure occurred in three patients. Transient hypothermia occurred without evidence of infection in 8 patients (median age 8 months, range, 2 days to 5 years). Cerebral infarction defined by computed tomographic scanning occurred in 3 patients of 12, 14 and 26 months of age and in 2 patients after an INTV procedure (recoarctation dilation in 1 and an atrial septal defect closure in the other). These events were thought to be related to transient cerebral hypoperfusion in one patient (18)or an inadvertent air embolism in two. Seizures complicated two procedures, following a supraventricular tachycardia in one patient and a drug reaction in another. One major complication occurred in a patient undergoing emergency stent implantation into the right pulmonary artery within days after attempted surgical repair. The child became hypotensive after the implant, had the chest opened and clots around the heart removed. No discrete bleeding sites were observed and the child was returned to the intensive care unit, ultimately recovering.
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.
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).
Complications after aortic valve dilation were the most frequent of any INTV procedures (42%), a similar incidence as reported in the literature (1,3,5). Arterial complications occurred in 29 cases, and appears related to patient age (1,3,5), occurring in 18 of 19 infants in whom a complication occurred. Severe aortic insufficiency occurred in three patients, requiring surgical repair of the aortic valve. Recoarctation angioplasty similarly had a high incidence of complications (32% of procedures, primarily arterial). This is less than that reported by Booth et al. (5)(53%), although these authors did not differentiate dilation of native from recurrent obstructions. Our incidence, however, was greater than that reported by Fellows et al. (3)(4%), in part due to our younger patient age (median age 12.5 months vs. 3.7 years). As for aortic valve dilation, the insertion of a large catheter into the artery was the substrate for an arterial complication, common at all ages (33.7% of all complications) and greatest in infants (41% of infant complications).
These had the lowest rate of morbidity. Major complications occurred in only 0.7%, less than those occurring during INTV (2.0%) procedures and similar to the incidence observed during DGN procedures (0.8%).
Although significant improvements have occurred in the diagnosis and management of the critically ill patient with congenital heart disease, complications of cardiac catheterizations cannot be avoided, although such events occur less frequently than in the last decade. The morbidity associated with INTV catheterizations is significantly higher than other types of procedures, although with an increasing proportion of such catheterizations, an increasing incidence may be expected. Efforts to further reduce mortality and morbidity can be accomplished by improving equipment, catheter flexibility and reduced procedure times. Prospective studies for defining risk and impact on patient outcomes should be encouraged.
We thank Alice Newman for time and help given in statistical evaluation.
- electrophysiologic sudy
- Received October 28, 1997.
- Revision received June 25, 1998.
- Accepted July 15, 1998.
- American College of Cardiology
- Lock J.E,
- Keane J.F,
- Fellows K.E
- Cassidy S.C,
- Schmidt K.G,
- Van Hare G.F,
- Stanger P,
- Teitel D.F
- Booth P,
- Redington A.N,
- Shinebourne E.A,
- Rigby M.L
- Stanger P,
- Heymann M.A,
- Tarnoff H,
- Hoffmann J.I.E,
- Rudolf A.M
- Ho C.S,
- Krovetz J.L,
- Rowe R.D
- Braunwald E,
- Gorlin R,
- McIntosh H.D,
- Ross R.S,
- Rudolf A.M,
- Swan H.J.C
- ↵Delisle G, Izukawa T, Olley PM, Kidd BSL. Risk factors in cardiac catheterization in newborn. Abstract. Canadian Cardiovascular Society. 25th Annual Meeting. Toronto, Ontario, Canada, 1972:28.
- Beekman R.H,
- Lloyd T.R
- Keane J.F,
- Lock J.E,
- Perry S.B
- Burrows P.E,
- Benson L.N,
- Williams G.W,
- et al.
- Burrows P.E,
- Benson L.N,
- Babyn P,
- MacDonald C
- Nykanen D.G,
- Hayes A.M,
- Benson L.N,
- Freedom R.M
- Kan J.S,
- White R.I,
- Mitchell S.E,
- Anderson J.H,
- Gardner T.J
- Hayes A.M,
- Redington A.N,
- Rigby M.L
- Rowe R.D
- Huhta J.C,
- Glasgow P,
- Murphy D.J Jr.,
- et al.
- Freed M.D,
- Keane J.F,
- Rosenthal A
- Kocis K.C,
- Snider A.R,
- Vermilion R.P,
- Beekman R.H
- Dessy H,
- Hermus J.P,
- van den Heuvel F,
- Oer H.Y,
- Krenning E.P,
- Hess J