Usefulness of PREDIC3T Case Type Risk Category in the CRISP Registry.

Procedural risk in Congenital Cardiac Catheterization (PREDIC3T) was recently reported as the contemporary procedure-type risk metric by the Congenital Cardiac Catheterization Project on Outcomes (C3PO) registry. The usefulness of this metric has not been evaluated elsewhere. The CRISP registry of Congenital Cardiovascular Interventional Study Consortium (CCISC) data set was analyzed. The study period was 14 years (2009 to 2022). The primary outcome was significant adverse event (SAE). Cases were assigned to the 6 PREDIC3T risk categories. Univariate and multivariable logistic regression models were used to evaluate the association between PREDIC3T and the primary outcome. The model discriminative performance was evaluated by the c-statistic. In a total of 64,419 enrolled cases, PREDIC3T case types were assigned in 59,822 cases (93%). The frequency for PREDIC3T category was 0 = 7,494 (12.5%), 1 = 16,932 (28.3%), 2 = 17,023 (28.5%), 3 = 9,885 (16.5%), 4 = 4,403 (7.4%), and 5 = 4,085 (6.8%). SAE was observed in 2,474 cases (4.1%). The SAE rates for category were 0 = 1.0%, 1 = 2.3%, 2 = 4.0%, 3 = 6.2%, 4 = 8.2%, and 5 = 9.0%. In a multivariable model, PREDIC3T case type risk category (odds ratios for category: 0 = 0.49, 1 = 1.00, 2 = 1.40, 3 = 2.06, 4 = 2.79, and 5 = 3.15; p <0.001) were significantly associated with SAE (c-statistic of 0.707) after adjusting for age, preprocedural inotropic support and systemic illness, low systemic saturation, high pulmonary vascular resistance, and the use of general anesthesia. The PREDIC3T case type risk category was associated with the risk of SAE in the CRISP registry data set and appeared to be a useful procedural risk classification tool.

Amplatzer Piccolo Occluder clinical trial for percutaneous closure of the patent ductus arteriosus in patients ≥700 grams.

OBJECTIVES: Characterize the safety and effectiveness of the Amplatzer Piccolo Occluder for patent ductus arteriosus (PDA) closure. BACKGROUND: The presence of a hemodynamically significant PDA has been associated with an increased risk of morbidity and mortality in children born premature. METHODS: This was a single arm, prospective, multicenter, non-randomized study to evaluate the Amplatzer Piccolo Occluder to treat PDA in patients ≥700 g. From June 2017 to February 2019, 200 patients were enrolled at nine centers, with 100 patients weighing ≤2 kg. Primary effectiveness endpoint was the rate of PDA closure at 6-month follow-up. Primary safety endpoint was the rate of major complications through 6 months. Secondary endpoint was rate of significant pulmonary or aortic obstruction through 6 months' follow-up. RESULTS: The implant success rate was 95.5% (191/200) overall and 99% in patients ≤2 kg (99/100). The primary effectiveness endpoint was achieved in 99.4% of implanted patients. Four patients experienced a primary safety endpoint event (2 transfusions, 1 hemolysis, and 1 aortic obstruction). There were no branch pulmonary artery obstructions. Five patients, all ≤2 kg, were noted to have worsening of tricuspid regurgitation (TR) after the procedure. None of the TR incidences manifested clinically. The Amplatzer Piccolo Occluder received FDA approval in January 2019 and became the first device approved for PDA closure in patients ≥700 g. CONCLUSIONS: This study supports the safety and effectiveness of the Amplatzer Piccolo Occluder, particularly in patients between 700 g and 2 kg where there is currently a significant unmet need in the United States. ClinicalTrials.gov identifier: NCT03055858.

A Model for Assessment of Catheterization Risk in Adults With Congenital Heart Disease.

The purpose of this study was to define the risk for adults with congenital heart disease who underwent cardiac catheterization and to propose a precatheterization risk scoring system. Data were prospectively collected using a multicenter registry of the Congenital Cardiovascular Interventional Study Consortium. The occurrence of serious adverse events (SAE) was correlated with 12 predefined variables. Catheterization RISk in Adult patients (CRISA) score was derived using multivariate logistic regression with backward elimination model selection method. The CRISA score was compared with the American Society of Anesthesiology score and a consensus-derived, 20-point risk score based on their ability to predict SAE. From June 2008 to September 2017, 300 adjudicated SAE's occurred in 7317 catheterization procedures (overall SAE rate 4.1%) performed in adults over 18 years of age at 27 contributing centers. Nine of the 12 tested variables were ultimately included in the CRISA score. CRISA score positively correlated with risk of SAE, and was superior to American Society of Anesthesiology and the 20-point risk score in predicting SAE. Minimal (CRISA score 0 to 2), low (3 to 7), moderate (8 to 10) and high (≥11) risk categories were identified, corresponding to 0.5%, 3.2%, 7.9%, and 16.7% risk of SAE, respectfully. In conclusion, the CRISA score reliably predicts risk of SAE in adults with congenital heart disease who underwent cardiac catheterization and may be useful for preprocedural risk assessment.

Validation and refinement of the catheterization RISk score for pediatrics (CRISP score): An analysis from the congenital cardiac interventional study consortium.

OBJECTIVES: To externally validate the CRISP score, and determine if refinements might improve clinical utility. BACKGROUND: The CRISP score estimates risk of serious adverse events (SAEs) for pediatric catheterization. METHODS: Pediatric (age < 18) procedures reported to the Congenital Cardiovascular Interventional Study Consortium registry from 05/08 to 09/17 (n = 29,830, 27 centers) were divided into a development dataset of 14,784 earlier procedures, and a validation dataset of 15,046 more recent procedures. The development dataset was used to refit the original CRISP model, and to develop a revised(r) CRISP score, consisting of entirely pre-procedurally collected data. The validation dataset was then used to compare model fit and risk prediction between CRISP, rCRISP and two existing risk scores using Akaike's (AIC), Schwarz's (BIC) Bayes Information Criteria, -log Likelihood (N2LL), area under the receiver operator curve and chi-square goodness-of-fit statistic (across 5 risk categories). RESULTS: Overall 4.31% of patients experienced at least one SAE with frequency increasing from 1.08% in CRISP category 1 to 27.34% in category 5. Both CRISP and rCRISP (entirely pre-procedural) predicted risk of SAEs well, with observed to predicted ratios ranging from 0.71 to 1.18 across the 5 risk categories. Compared to the original CRISP score, rCRISP demonstrated less optimal model fit (higher AIC, BIC, and N2LL) but similar risk prediction (C-statistic = 0.71 vs. 0.70; chi-squared statistic = 6.77 vs. 6.85). CONCLUSION: The CRISP score accurately predicts procedural risk. With minor modifications, the revised version (rCRISP) performed well with arguably greater clinical utility as an entirely preprocedural risk model.

CRISP: Catheterization RISk score for Pediatrics: A Report from the Congenital Cardiac Interventional Study Consortium (CCISC).

OBJECTIVES: We sought to develop a scoring system that predicts the risk of serious adverse events (SAE's) for individual pediatric patients undergoing cardiac catheterization procedures. BACKGROUND: Systematic assessment of risk of SAE in pediatric catheterization can be challenging in view of a wide variation in procedure and patient complexity as well as rapidly evolving technology. METHODS: A 10 component scoring system was originally developed based on expert consensus and review of the existing literature. Data from an international multi-institutional catheterization registry (CCISC) between 2008 and 2013 were used to validate this scoring system. In addition we used multivariate methods to further refine the original risk score to improve its predictive power of SAE's. RESULTS: Univariate analysis confirmed the strong correlation of each of the 10 components of the original risk score with SAE attributed to a pediatric cardiac catheterization (P < 0.001 for all variables). Multivariate analysis resulted in a modified risk score (CRISP) that corresponds to an increase in value of area under a receiver operating characteristic curve (AUC) from 0.715 to 0.741. CONCLUSION: The CRISP score predicts risk of occurrence of an SAE for individual patients undergoing pediatric cardiac catheterization procedures.

Hybrid approach to the comprehensive stage II operation in a subset of single-ventricle variants.

OBJECTIVE: The objective of a hybrid approach to staged palliation of single-ventricle anomalies is designed to minimize the trauma of the first stage. However, the second stage is a complex procedure that may negate the advantages of the first stage. We sought to devise a "hybrid" approach to the second stage when aortic outflow is expected to remain unobstructed. METHODS: The procedure involves a simple incision into the main pulmonary artery, dilation/stenting of the ductal continuation, formation of a stented baffle between the branch pulmonary arteries' orifices, and a bidirectional Glenn connection. It avoids dissection of the distal arch and ductal continuation and obviates the need for a Damus-Kaye-Stansel connection. We carried out this procedure in 2 patients, one with unbalanced atrioventricular canal and the other with mitral atresia. RESULTS: Both patients underwent an uncomplicated operative procedure. Both patients were successfully weaned from the ventilator, with no clinically evident neurologic injury. The first patient died of complications related to thrombosis of the left pulmonary artery before initiation of anticoagulation. The second patient is alive and well 1 year postoperation with no obstruction to either systemic or pulmonary flow and no baffle leak and good right ventricle function. CONCLUSIONS: This hybrid comprehensive stage II operation appears feasible and technically simpler than the conventional comprehensive stage II procedure. It is applicable to a subset of single-ventricle cases in which aortic outflow is anticipated to remain unobstructed. We recommend early postoperative anticoagulation to avoid early left pulmonary artery thrombosis.

Standardizing radiation dose reporting in the pediatric cardiac catheterization laboratory-a multicenter study by the CCISC (Congenital Cardiovascular Interventional Study Consortium).

OBJECTIVES: We examine normalized air Kerma area product (PKA ) by body weight (PKA /BW) as a reference value of radiation dose and benchmark PKA /BW in pediatric laboratories using a multicenter registry database. BACKGROUND: Reduction of radiation dose is an important quality improvement task in pediatric cardiac catheterization laboratories. Physicians need to agree on a standard method of reporting radiation dose that would allow comparisons to be made between operators and institutions. METHODS: This was a multicenter observational study of radiation dose in pediatric laboratories. Patient demographic, procedural and radiation data including fluoroscopic time and PKA (µGy m(2) ) were analyzed. PKA /BW was obtained by indexing PKA to body weight. RESULTS: A total of 8,267 pediatric catheterization procedures (age <18 years) were included from 16 institutions. The procedures consisted of diagnostic (n = 2,827), transplant right ventricular (RV) biopsy (n = 1,172), and interventional catheterizations (n = 4268). PKA correlated with body weight better than with age and best correlated with weight-fluoroscopic time product. PKA /BW showed consistent values across pediatric ages. Interventional catheterizations had the highest PKA /BW (50th, 75th, and 90th percentiles: 72, 151, and 281 µGy m(2) /kg), followed by diagnostic (59, 105, and 175 µGy m(2) /kg) and transplant RV biopsy (27, 79, and 114 µGy m(2) /kg). CONCLUSION: PKA /BW appeared to be the most reliable standard to report radiation dose across all procedure types and patient age. We recommend PKA /BW to be used as the standard unit in documenting radiation usage in pediatric laboratories and can be used to evaluate strategies to lower radiation dosage in pediatric patients undergoing cardiac catheterizations. © 2014 Wiley Periodicals, Inc.

Balloon angioplasty and stent implantation performed through systemic-to-pulmonary artery shunts in infants and neonates.

Branch pulmonary artery stenosis (BPAS) in the setting of systemic-pulmonary artery shunts (SPS) may result in significant sequelae. Limited information exists regarding the safety and efficacy of pulmonary artery balloon angioplasty and stent implantation via SPS in neonates and infants. This study aimed to examine the feasibility, safety, and efficacy of balloon angioplasty/stent implantation for BPAS performed via SPS in neonates and infants. A single-center retrospective analysis of all patients weighing 10 kg or less who underwent angioplasty for BPAS via SPS was performed. Systemic oxygen saturations and vessel diameter before, during, and after the procedure were compared. Between July 1996 and February 2008, 15 patients underwent 20 catheterizations for the treatment of 27 BPAS via SPS. The patients had a mean weight of 5.6 kg (range, 2.6-10 kg) and a mean age of 7.6 months (range, 7 days to 33 months). The SPS diameter ranged between 2 and 5 mm (median, 3.5 mm). Angioplasty was performed for all 27 lesions, and an additional stent was placed in 5 of these. The average lesion diameter increased from 2.3 ± 1.5 to 4.7 ± 1.7 mm (p < 0.05), and 25 (93 %) of the 27 lesions met the predetermined criteria for success. Systemic oxygen saturation increased from 73 ± 9.5 % to 82 ± 6.8 % immediately after intervention and was 83 ± 7.9 % at discharge (p < 0.05). There were no instances of shunt thrombosis. Two patients experienced transient hypotension during the procedure. No procedural deaths occurred. The study findings suggest that balloon angioplasty or stent implantation performed via SPS appears to be safe and effective treatment for BPAS in neonates and infants.

Shunt reduction to pulmonary arteriovenous malformations using a modified covered stent.

Pulmonary arteriovenous malformations in patients with congenital heart disease have been associated with interruption of hepatic venous return to the lungs. We report a novel technique to improve systemic saturation using a modified covered stent in a patient with unilateral left pulmonary arteriovenous malformations in the setting of a Fontan circulation.

The Fontan operation: the pursuit of associated lesions and cumulative trauma.

Our programmatic approach to the Fontan operation has evolved to include using an extracardiac conduit with aggressive presumptive treatment of associated lesions either in the catheterization laboratory or the operating room. Fenestration is used selectively based on hemodynamics, anatomy, and presence of associated lesions. We reviewed our experience to determine the effectiveness and outcome of this strategy and to assess the cumulative trauma to the patients. The records of 137 consecutive patients who underwent Fontan at Miami Children's Hospital from 1995 to 2008 were reviewed. At mean follow up of 5.76 years, freedom from death or transplantation is 94.2% (129/137). Median age at operation was 4.6 years. Longer length of stay correlated with older operative age (P = 0.0056). Pacemakers were implanted in 11.7% (16/137). Additional (not pre-Glenn or pre-Fontan) interventional catheterizations were performed in 51.8% (71/137). Additional operations were done in 10.2% (14/137). No patient has required replacement or revision of the extracardiac conduit. Our current approach to the Fontan operation provides acceptable midterm results. The pursuit of residual lesions results in a significant number of additional interventional catheterizations and operative procedures but might have an important influence on long-term survival after the Fontan procedure.

Computed tomography angiography successfully used to diagnose postoperative systemic-pulmonary artery shunt narrowing.

In recent years, there has been a marked reduction in surgical mortality for many complex forms of congenital heart disease. Treatment or palliative strategies vary but may include systemic-pulmonary central or Blalock-Taussig shunt. These shunts can be complicated by overcirculation, infection, thrombosis, and thromboembolism. Many diagnostic modalities are available to aide in diagnosis of postoperative shunt complications including echocardiography and cardiac catheterization but these may be invasive, inconclusive, or difficult to obtain adequate images. Computed tomography angiography (CTA) has many attributes that make it potentially useful in the evaluation of congenital heart disease and postoperative shunt complications. We report one patient where CTA guided the post-operative algorithm and appropriately identified a shunt narrowing despite repeated echocardiograms showing a patent shunt. These findings along with clinical suspicion appropriately guided us toward cardiac catheterization. To our knowledge, this is the first paper where CTA appropriately suspected a shunt narrowing in the absence of echocardiographic confirmation.

Unnatural history of the right ventricle in patients with congenitally malformed hearts.

The long-term outcome of patients with congenitally malformed hearts involving abnormal right ventricular morphology and haemodynamics is variable. In most instances, the patients are at risk for right ventricular failure, in part due to morphological differences between the right and left ventricles and their response to chronic volume and pressure overload. In patients after repair of tetralogy of Fallot, and after balloon valvotomy for valvar pulmonary stenosis, pulmonary regurgitation is the most significant risk factor for right ventricular dysfunction. In patients with a dominant right ventricle after Fontan palliation, and in those with systemic right ventricles in association with surgically or congenitally corrected transposition, the right ventricle is not morphologically capable of dealing with chronic exposure to the high afterload of the systemic circulation. In patients with Ebstein's malformation of the tricuspid valve, the degree of atrialisation of the right ventricle determines how well the right ventricle will function as the pump for the pulmonary vascular bed.

Infantile form of scimitar syndrome with contralateral pulmonary vein stenosis.

Infantile scimitar syndrome (SS) carries significant mortality. Consistent management guidelines have not been well established, and outcomes continue to be disappointing. We present our experience managing an SS patient with complex anatomy who developed stenosis of the pulmonary veins contralateral to the hypoplastic lung.

Dexmedetomidine/ketamine for diagnostic cardiac catheterization in a child with idiopathic pulmonary hypertension.

The use of a combination of dexmedetomidine and ketamine to provide procedural sedation in a 12-year old boy with a diagnosis of idopathic pulmonary hypertension and a behavioral disorder, undergoing diagnostic cardiac catheterization, is presented. Following a loading dose of ketamine one mg/kg and dexmedetomidine one mcg/kg, an infusion of dexmedetomidine at one mcg/kg/hr was used with the patient breathing spontaneously. Stable hemodynamics were observed throughout the procedure and pulmonary vascular resistance was measured under three conditions. The dexmedetomidine infusion was continued for two hours post-catheterization, facilitating a smooth emergence.

Early experience with a simplified technique for transcatheter closure of the patent foramen ovale.

BACKGROUND: Although generally safe, transcatheter patent foramen ovale (PFO) closure typically involves catheter exchanges and manipulations within the left atrium (LA) that may result in complications. We describe the development of a simplified technique for PFO closure, further to modification of our earlier approaches. METHODS: Early in our experience, LA angiography and/or balloon sizing of the PFO was routine prior to device closure. Subsequently, the simplified technique described herein became our standard approach. We reviewed immediate and medium term results in 27 consecutive patients who underwent closure in a 24-month time frame. RESULTS: All procedures used general anaesthesia, TEE guidance and CardioSEAL septal occluder. Device delivery was successful in all patients. The median fluoroscopy time was significantly shorter with the simplified technique (median difference 6.7min, p<0.05) with a 98.3% median confidence interval (4.5, 19.9min). There were four complications, all occurring in the early group of patients. There have been no recurrent neurological events or device related adverse events on medium term follow-up. CONCLUSIONS: Successful transcatheter PFO closure is feasible without LA angiography or catheter-based balloon sizing, utilising echocardiographic guidance for device selection and placement. Simplification of PFO closure technique could potentially decrease complications and shorten fluoroscopy times.

Midterm results for collaborative treatment of pulmonary atresia with intact ventricular septum.

BACKGROUND: We report a single-institution experience using a collaborative surgical and catheter-based approach to the initial treatment of pulmonary atresia with intact ventricular septum. METHODS: A retrospective review was conducted of all neonates admitted with pulmonary atresia with intact ventricular septum from 1996 to March 2007. RESULTS: We identified 24 patients with a mean age at first intervention of 4.5 days with mean follow-up of 6.05 years (range, 1.9 to 12.7 years). Initial palliation was determined by right ventricular size, morphology, and presence or absence of right ventricular-dependent coronary circulation. Initial catheter-based pulmonary valve perforation and valvuloplasty was performed in 41.7% (10 of 24 patients; group A), and 58.3% (14 of 24 patients) had an initial systemic-to-pulmonary artery shunt (group B). Tricuspid valve size was significantly smaller in group B (median z-score, -0.52 group A versus -2.40 group B; p < 0.001). Placement of a shunt after valvuloplasty in group A was required in 70.0% (7 of 10 patients). There was no mortality in group A, and 70.0% (7 of 10 patients) are in a two-ventricle pathway and 30.0% (3 of 10 patients) are in a 1.5-ventricle pathway. Group B had mortality of 14.3% (2 of 14 patients), both within 5 days of surgery. All group B patients remain in a single-ventricle pathway. Overall survival is 91.7% (22 of 24 patients). CONCLUSIONS: An individualized approach to this complex lesion has good results. If the right ventricle can be safely decompressed and appears usable, the need for a shunt after valvuloplasty does not preclude two-ventricle (or 1.5-ventricle) repair. Anatomy mandating a shunt as initial palliation has substantial early mortality.

The successful use of alternative routes of vascular access for performing pediatric interventional cardiac catheterization.

OBJECTIVE: The objective of this study is to examine the safety/efficacy of alternative routes of vascular access (ARVA) for successful performance of interventions. BACKGROUND: Complex interventional catheterizations may be required in children with limited vascular access, vascular constraints relative to size, and hemodynamic instability. Our approach has been to utilize ARVA in selected cases. METHODS: ARVA pertains to any vessel excluding femoral, jugular/subclavian veins, or umbilical access. A retrospective review performed on patients with an intervention utilizing ARVA between August 1995 and January 2004 was performed. Patients were divided by clinical status: critically ill/emergent (A), elective cases (B). Procedural success was based on previously published criteria. RESULTS: Sixty-four interventions were performed in 50 patients using 54 ARVA. ARVA utilized: radial (1), axillary (2), brachial (2), carotid arteries (25); brachial (2) hepatic (9) veins; and open chest/direct cardiac puncture (13). ARVA provided successful access to target lesions. Interventions included stents (30), valvuloplasty (16), angioplasty (14), and one each of vascular occlusion, septal occlusion, accessory pathway ablation, and septostomy. Group A patients were smaller (P < 0.0002) and younger (P < 0.004) than B. All open chest/direct cardiac and the majority (71%) of carotid arterial approaches were performed in group A. Fifty-six (88%) inteventions were successful with no difference between groups A (88%) and B (86%). There were two complications. Neither resulted in long-term sequelae. CONCLUSIONS: ARVA may provide a strategic advantage that may be safely applied to a variety of interventions regardless of patient size or degree of illness. These techniques may further extend the scope of successful interventions in children.

Stent implantation is effective treatment of vascular stenosis in young infants with congenital heart disease: acute implantation and long-term follow-up results.

BACKGROUND: Stents implantation in infants has been shown to be feasible, however, there are no published reports examining long-term outcomes. Concerns exist regarding creation of fixed obstructions secondary to the stent if expansion to larger diameters over time is not possible. METHODS: A retrospective analysis of the earliest consecutive series of infants who underwent stent placement at our institution between October 1995 and December 1999. RESULTS: Implantation of 33 stents were attempted in 27 infants, median age = 10 (25-24) months, wt = 8.1 (3.4-14.5) kg. Stents used were as follows: 16 large, 13 medium, and 4 coronary. Acute implant success was 94%. There were three nonprocedure-related deaths within 30 days of implantation, 1 patient was lost to follow-up and 1 had acute stent thrombosis. The remaining 22 patients (26 stents) form the long-term follow-up study group. Nineteen stents underwent 33 redilations. Following latest redilation, 67.0 (37-113) months postimplantation, minimal luminal diameter increased from 7.0 +/- 1.8 mm immediately following implantation to 8.7 +/- 2.3 mm (P < 0.001). Seven stents were electively removed/ligated during a planned surgery. All 18 remaining in situ stents are patent without significant obstruction 102 (84-116) months following implantation. There was one late death 51 months after stent implantation. The remaining 21 patients are alive and well. CONCLUSIONS: Stent implantation in infants is safe and effective. Serial redilation is possible to keep pace with somatic growth; however, efforts should be made to implant stents with adult diameter potential in children who will not require further cardiac surgery. Implantation of small- and medium-sized stents can provide effective palliation and should be considered in carefully selected infants who will ultimately require future surgery.

Initial experience with dexmedetomidine for diagnostic and interventional cardiac catheterization in children.

BACKGROUND: Children undergoing diagnostic and interventional cardiac catheterization require deep sedation or general anesthesia (GA). Dexmedetomidine, a selective alpha-2 adrenergic agonist, has sedative, analgesic and anxiolytic properties without respiratory depression. These characteristics make it potentially suitable as a sedative agent during diagnostic procedures in children. We report our experience using dexmedetomidine in 20 children aged 3 months to 10 years undergoing cardiac catheterization. METHODS: Following a midazolam premedication, intravenous access was secured facilitated by the inhalation of sevoflurane in oxygen. A loading dose of 1 microg x kg(-1) dexmedetomidine was administered over 10 min followed by an initial infusion rate of 1 microg x kg(-1) x h(-1). Nasal cannulae were applied, allowing endtidal CO2 monitoring with the patients breathing spontaneously. Hemodynamic parameters, Bispectral Index Score (BIS) and sedation score were measured every 5 min. Patient movement or evidence of inadequate sedation were treated with propofol (1 mg x kg(-1)). The dexmedetomidine infusion rate was titrated to the level of sedation to a maximum of 2 microg x kg(-1) x h(-1) to maintain a sedation score of 4-5 and a BIS value <80. RESULTS: Five patients (25%) had some movement on local infiltration or groin vessel access. This did not necessitate restraint or result in difficulty securing vascular access. No patients failed sedation that required the addition of another sedative agent or conversion to GA; eight patients were sedated with dexmedetomidine alone; however, 12 (60%) patients did receive a propofol bolus at some time during the procedure due to movement, increasing BIS value or in anticipation of stimulation. There were no incidences of airway obstruction or respiratory depression. In all cases the heart rate and blood pressure remained within 20% of baseline. No patient required treatment for profound bradycardia or hypotension. The average infusion rate for dexmedetomidine following the loading dose was 1.15 (+/-0.29)microg x kg(-1) x h(-1) (range 0.6-2.0 microg x kg(-1) x h(-1)). CONCLUSIONS: This initial experience showed dexmedetomidine, with or without the addition of propofol, may be a suitable alternative for sedation in spontaneously breathing patients undergoing cardiac catheterization.