Asian Cardiovasc Thorac Ann 2002;10:129-132
© 2002 Asia Publishing EXchange Pte Ltd
Arterial Complications Following Cardiac Catheterization in Children Less Than 10 kg
Ziad R Bulbul, MD,
Mohammed Omar Galal, MD,
Elsayed Mahmoud, BS,
Bettina Narden, MD,
Laszlo Solymar, MD,
Mohammad Ashraf Chaudhary, PhD,
Zohair Y Al Halees, MD
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Department of Cardiovascular Diseases King Faisal Specialist Hospital and Research Centre Riyadh, Saudi Arabia
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Ziad R Bulbul, MD Tel: 966 1 442 7470 Fax: 966 1 442 7482 email: zrbulbul{at}hotmail.com Department of Cardiovascular Diseases (MBC-16), King Faisal Specialist Hospital and Research Centre, P.O. Box 3354, Riyadh 11211, Saudi Arabia.
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ABSTRACT
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We sought to determine if a higher dose of heparin would reduce arterial complica-tions in patients weighing 10 kg or less undergoing cardiac catheterization to investigate congenital heart disease. Sixty patients were given either 100 (group A) or 150 (group B) IU•kg-1 of heparin in a double-blinded randomized manner. Initial arterial access was established using a 4F cannula in all patients. Mean activated clotting time measured 20 minutes following heparin administration was significantly lower in group A than in group B (199 versus 251 seconds). Only 3 out of 60 patients (5%) required treatment for loss of femoral pulse. The age, weight, activated clotting time, length of catheterization procedure, time taken to establish arterial access, and the duration of arterial cannulation were comparable between the groups. Weight under 4 kg, age under 1 month, and cannula size larger than 4F were identified as independent risk factors for the development of arterial complications. Arterial access using a 4F cannula is a safe procedure in children weighing 10 kg or less. The incidence of significant arterial complications is low, and they do not appear to be preventable by a higher dose of heparin.
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INTRODUCTION
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Femoral artery occlusion has been identified as one of the most frequently occurring complications following percutaneous cannulation. Thrombosis and thrombo-embolic phenomena are most probably responsible for the majority, but not all, of these complications.
Since the introduction of systemic heparinization in 1970, the incidence of femoral artery thrombosis has fallen to about 1% to 8%.1–5 In spite of the widespread use of heparin in cardiac catheterization, there is still neither an agreement on the appropriate dosage nor a consensus on what constitutes adequate anticoagulation.2–8 Major studies1,9 aimed at predicting thrombosis or formulating a protocol for the use of heparin included patients with a wide range of ages and body weights. Hence, recom-mendations are not specific.
Heparin dosages of 50 and 100 IU•kg-1 are commonly used in cardiac catheterization of pediatric patients. A body weight < 10 kg has been identified as a risk factor despite adequate heparinization.1 We sought to determine the effect of a higher dose of heparin (150 IU•kg-1) on the incidence of arterial complications in patients with congenital heart disease and a body weight of 10 kg or less undergoing cardiac catheterization. We also attempted to identify additional risk factors in a double-blinded randomized fashion.
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PATIENTS AND METHODS
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Sixty patients with a body weight of 10 kg or less undergoing cardiac catheterization to investigate con-genital heart disease were enrolled over a 1-year period. They were given heparin at either 100 (group A) or 150 (group B) IU•kg-1 of body weight in a double-blinded randomized manner. Informed consent was obtained from the parents of all patients. Before catheterization, the age, weight, hemoglobin concentration, prothrombin time, partial thromboplastin time, platelet count, and arterial oxygen saturation were obtained. Diagnostic hemo-dynamic cardiac catheterization was performed. Additional left-sided intervention procedures were performed in 8 patients (aortic valvuloplasty in 4, coarctation angioplasty in 3, and aortopulmonary collateral embolization in 1). Initial arterial access in all patients was established percutaneously using a 4F sheath (Cordis Inc., Miami, FL, USA). Heparin was given as a bolus through the side arm of the sheath immediately after access was estab-lished. All sheaths and catheters, before and after the administration of heparin, were routinely flushed with heparinized saline (1 IU•mL-1). A blood sample was collected approximately 20 minutes following heparin administration for the measurement of activated clotting time (ACT) using a double-chambered ACT machine (HemoTec Inc., Englewood, CO, USA).
In 3 of the patients undergoing left-sided intervention, the arterial sheath was changed to a 5F one. In the remaining 5 patients, a balloon with a diameter of 4 to 12 mm and a shaft diameter of 4F to 6F was advanced through the skin over a wire.
Hemostasis was achieved by applying firm pressure just above the site of skin entry. The site was left exposed without dressing for at least 2 hours. Thereafter, the popliteal, dorsalis pedis, and posterior tibial pulses were checked every 15 minutes until they appeared.
Patients without pulses for 6 hours were treated with 50 IU•kg-1 of heparin given as a bolus followed by con-tinuous infusion of a maintenance dose of 25 IU•kg-1. Partial thromboplastin time twice that of control was sought and maintained. Patients were kept on heparin therapy for 24 hours. Antithrombotic treatment with streptokinase was started if pulses were not palpable and the ipsilateral extremity was showing signs of decreased perfusion 24 hours following the initiation of heparin therapy. Following the administration of an initial loading dose of 4,000 IU•kg-1, a maintenance dose of 1,000 IU•kg-1 was given through a continuous drip. Serum level of fibrinogen was maintained at above 2 g·L-1.
The results are expressed as mean ± standard deviation. Differences are considered significant if p < 0.05.
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RESULTS
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The age, weight, hemoglobin level, platelet count, prothrombin time, partial thromboplastin time, and oxygen saturation were comparable between groups A and B before catheterization (Table 1
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Of the 8 patients who underwent additional left-sided intervention procedures, 7 were in group B (Table 2). The volume of contrast (Omni Paque; Nycomed Inc., Oslo, Norway) used per kilogram of body weight was comparable between the groups. Group A had a lower mean ACT level of 199.3 ± 53 seconds compared to 251 ± 113.9 seconds in group B. However, both groups were comparable in respect of the time to arterial cannulation, the duration of arterial cannulation, and the duration of the catheterization procedure. The duration of arterial cannulation is defined as the time from the insertion of the cannula until its removal. The time to arterial cannulation is the time taken to establish cannulation, which reflects the degree of difficulty in obtaining arterial access.
Three out of 60 patients (5%), all from group B and all underwent intervention procedures, required treatment for loss of pulse. The mean age of these 3 patients was 1 ± 0 month and their weight was 3.7 ± 0.4 kg. Two of them were treated successfully with heparin, while the third required additional treatment with streptokinase. All had palpable pulses upon discharge from the hospital.
Logistic regression analysis of relevant variables (age, weight, heparin dosage, time to cannulation, duration of cannulation, total procedure time, and arterial cannula size) identifies weight below 4 kg, age under a month, and a sheath larger than 4F as independent risk factors for arterial complications that require treatment.
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DISCUSSION
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Despite consensus on the risk of arterial complications and the widespread use of heparin for systemic anticoagulation during cardiac catheterization, there is little information on what constitutes an adequate dose of heparin. Infants weighing < 10 kg are at an even higher risk, especially if undergoing intervention procedures.9
In older children, the rate of vascular complications occurring after intervention procedures has been reported to be 3 to 6 times higher than in diagnostic procedures despite systemic heparinization.4–8 However, another study found that there were no arterial complications in children as long as the ACT was maintained above 200 seconds.9 It was also reported that the incidence of arterial complications rose from 5.2% to 12.9% in patients < 5 kg as the arterial sheath size increased from 4F to 5F.1 It rose further to 42.8% when the size increased to 6F.
In our study, it is difficult to speculate whether the relatively high doses of heparin used played a role in lowering the overall incidence of arterial complications (5%). However, it is clear that even a dose of 150 IU•kg-1 of heparin, resulting in a significantly prolonged ACT, did not eliminate the risk of arterial complications in infants weighing < 4 kg and undergoing intervention procedures. Hence, proper anticoagulation alone when using large cannulas will not prevent arterial complications in this patient population. As the number of patients with arterial complications is small (n = 3), firm conclusions about risk factors could not be made. However, we can speculate that the use of a relatively large cannula in an infant < 4 kg will completely or nearly completely occlude the flow to the artery distal to the entry site. This may predispose the area to clot formation despite the use of an appropriate dose of heparin and achieving an acceptable ACT. Flow studies in the femoral and popliteal arteries during cannulation might be valuable in proving this theory. In our series, such a theory could not be proven as none of our patients required surgical intervention, and hence pathological evidence is lacking.
On the other hand, none of our patients who had diagnostic cardiac catheterization using a 4F arterial cannula required treatment for arterial complications, regardless of the weight of the patient. This implies, contrary to current belief, that arterial cannulation in infants does not carry a high risk of arterial thrombosis. Long-term follow-up of these patients with emphasis on the quality of the femoral pulse and the ipsilateral extremity length and size is needed before firm recommendations can be made in this regard.
It is clear that infants weighing under 4 kg and younger than 1 month undergoing intervention procedures with arterial cannulas larger than 4F are at high risk for developing arterial complications (3 out of 8 patients in our series). However, it is heartening that these complica-tions are treatable medically without requiring surgical intervention. This association between low weight and larger cannula size and the increased risk of arterial complications should be taken only as a guide. We believe that the size of the artery itself is what matters and not the size of the patient.
Saxena and colleagues1 found that fewer attempts at arterial puncture and a shorter procedure time minimized the incidence of arterial complications. We found the concept of counting the number of arterial puncture attempts to be impractical. We used instead the time spent establishing arterial cannulation as an indicator of the degree of difficulty in obtaining arterial access. In our experience, the time spent to establish cannulation and the duration of arterial cannulation and of catheterization did not affect the incidence of complications.
In conclusion, arterial cannulation with a 4F sheath in infants weighing < 10 kg is relatively safe when heparin in a dose of 100 IU•kg-1 or more is given and an ACT of 200 seconds is achieved. Heparin at 150 IU•kg-1 did not eliminate the risk of arterial complications in infants < 4 kg when arterial cannulas larger than 4F were used, irrespective of the duration of cannulation or the time spent to establish access. In patients below 4 kg and under 1 month old, the use of arterial cannulas larger than 4F might be a risk factor for arterial complications.
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REFERENCES
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ABSTRACT
INTRODUCTION
