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Dr. Fagan is a Fellow in Echocardiography at the University of Ottawa Heart Institute. Dr. Chan is Professor of Medicine at the University of Ottawa Heart Institute.
Correspondence to: Kwan-Leung Chan, MD, University of Ottawa Heart Institute, 40 Ruskin St, Ottawa, Ontario, K1Y4W7; e-mail: kchan@ottawaheart.ca
Cardiac tamponade is a life-threatening condition that requires prompt diagnosis and management. Historically, the diagnosis of cardiac tamponade has been based on clinical findings. The classic triad of falling blood pressure, elevated systemic venous pressure, and quiet heart sounds is applicable mainly in the setting of acute onset of tamponade secondary to intrapericardial hemorrhage.1 These findings lack specificity, particularly in the patients who develop cardiac tamponade following cardiothoracic surgery. In this group of patients, other more common conditions such as left ventricular dysfunction can give rise to the same findings. The limitations of the clinical findings were confirmed in the study by Tsang et al in this issue of CHEST (see page 322). They examined the clinical and echocardiographic characteristics of significant pericardial effusions following cardiothoracic surgery at the Mayo Clinic over an 11-year period. The estimated incidence was 0.8%, with the highest incidence in heart transplant (8.4%) and the lowest in isolated coronary bypass surgery (0.2%). Anticoagulant use in 68% of these patients was the most common predisposing factor.
The detection of pericardial effusion has been greatly facilitated by the development of echocardiography, which is generally accepted as the gold standard diagnostic tool in the detection of pericardial effusion. The volume of the pericardial effusion can be semiquantitated and the hemodynamic effect assessed by looking for abnormal septal motion, right atrial or right ventricular diastolic collapse, and reduced respiratory variation of the diameter of the inferior vena cava.2 Furthermore, recent studies have shown that Doppler assessment of intracardiac flows and their relationship to respiration provides insight into the pathophysiology of this condition and can play a useful role in the diagnosis.2
While the role of echocardiography in the detection of pericardial effusion is not in doubt, its importance in the management of patients with significant pericardial effusions is not widely appreciated. After the diagnosis of a significant pericardial effusion, pericardiocentesis is generally required to alleviate the hemodynamic derangement and to prevent further deterioration. Pericardiocentesis, as it was originally described, is a blind procedure, and complications are not uncommon.3 And yet, this blind approach to the pericardial space almost exclusively from the subxyphoid area has persisted and remained the most widely used method.4 In so doing, little consideration is given to the comprehensive anatomic information provided by echocardiography, such as whether the effusion is loculated; the location of the effusion, if loculated; the presence of hematoma within the effusion; and, most importantly, the body surface location closest to the pericardial effusion. The Mayo Clinic group has advocated the echo-guided pericardiocentesis for almost 2 decades, predicated on the anatomic principle that the safest approach of pericardiocentesis is the most direct approach at the body surface location closest to the pericardial effusion without intervening vital structures.5 6 Echocardiography is thus not only an important diagnostic tool, but also has a key role in the treatment. The procedure and the necessary equipment have been described in detail by the same authors in a separate publication, which is a very good resource for anyone who is interested in adopting this procedure.7 Their overall results have been excellent, with very few complications.5 6 In the current study, Tsang et al focused on pericardial effusions in the postoperative setting. These patients represent a subgroup in whom pericardiocentesis can be technically more difficult because the pericardial effusions are more likely to be loculated. Echo-guided pericardiocentesis was highly successful with a very low complication rate, even in patients with loculated effusions. The most common needle entry site as selected by echocardiography was on the chest wall, usually near the cardiac apex, whereas the subxyphoid approach was employed in only 12% of patients. We like to underscore one subset of patients in whom catheter-based pericardiocentesis should not be attempted. These are patients whose pericardial effusions are made up of largely hematoma with very little free fluid. There were nine such patients in the series by Tsang et al. Pericardiocentesis was unsuccessful and surgical evacuation of the hematoma was necessary in all nine patients. We have previously reported a small group of such patients whose clinical presentation simulated cardiac tamponade despite the presence of little or no free fluid in addition to the pericardial hematoma.8 All of our patients also required surgical evacuation of the hematoma.
The echo-guided pericardiocentesis has been our preferred approach for about 15 years, with results very similar to those reported by the Mayo Clinic group. The effectiveness of this approach is best exemplified by the attitudinal change in our trainees after they have been exposed and trained in this technique. While they are reluctant and hesitant about the procedure before the exposure, they become enthusiastic advocates of this approach afterwards. We concur with the Mayo Clinic group that pericardiocentesis should no longer be "blind" but should be guided by the detailed anatomic information provided by echocardiography, with the only exception being emergency situations where echocardiography is not readily available. This latest contribution by the Mayo Clinic group provides additional valuable information that should help increase the popularity of the echo-guided pericardiocentesis.
Blind no more!
References
This article has been cited by other articles:
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  H Luckraz, S Kitchlu, and A Youhana Haemorrhagic peritonitis as a late complication of echocardiography guided pericardiocentesis Heart, March 1, 2004; 90(3): e16 - 16. [Abstract] [Full Text] [PDF]
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