Constrictive pericarditis is a type of subacute inflammations. Not only thickened parietal pericardium but also the fibrotic thickening visceral pericardium contributes to the pathogenesis of constriction. Surgical treatment is almost always required to remove the thickened and constricted visceral pericardium associated with removal of thickened parietal pericardium [1] [2]. Removal of the thickened visceral pericardium is a very difficult procedure because intense myocardial bleeding or injury to coronary arteries may occur. During the past several decades, many new techniques have been developed. One of the new techniques is to make transverse and longitudinal incisions in the visceral pericardium, cutting it into smaller fragments which allow the heart to successfully dilate and fill adequately, resulting in hemodynamic improvement. This method was originally presented by Heimbecker in 1983 [3]. This procedure was then called 'The Waffle Procedure'. However, this procedure still presents potential risks of unexpected bleeding caused by myocardial or coronary arteries injury, this is because the thickened visceral pericardium does not allow identification of the underlying correct anatomy of the coronary arteries and myocardium. Traditionally, typical surgical scalpels have been used for the Waffle procedure; however these scalpels are too large to ensure a fine control of the point of blade on the thickened and hardened visceral pericardium. Therefore, we employ a new surgical scalpel, the vessel knife D 500 (Mani, Utsunomiya, Tochigi, Japan), during the Waffle procedure (Figure 1).

The cardiac exposure is obtained through a median sternotomy in the usual manner. The constrictive pericarditis is also relieved in the usual manner including pericardiectomy with careful attention to the phrenic nerve preservation under cardiopulmonary bypass. When the heart is covered with thickened visceral pericardium consisting of dense fibrotic tissue, a series of visceral pericardial incisions, "the Waffle Procedure" begins in both the longitudinal and transverse directions using the vessel knife D 500. The entire surfaces of both ventricles and right atrium are incised in a similar manner until the visceral pericardium has been converted into small sections of scar tissue (Figure 2). The atrial and ventricular chambers begin to expand immediately with increasing ventricular contractility as the sections of visceral pericardium separate.

We have used this vessel knife in three patients with constrictive pericarditis (Table 1). No major intraoperative complications were observed, such as unexpected bleeding caused by myocardial or coronary arteries injury. The average amount of blood loss during the operation was 206 g. Although, preoperative NYHA functional class was III in all three patients, postoperative NYHA functional class improved to I in all patients. Postoperative echocardiography improved in diastolic function, including mitral annulus verocity (E') in all three patients [4] (Table 2). The ratio of lateral E' to septal E' (E'lat/ E'sep) were normalized to 1 or more. The patients are doing well after the operation without any sign of recurrence.

The vessel knife D 500 is specially designed for use in coronary artery dissection, hence why this knife has a small and very sharp blade which allows fine control at the point of the blade. Furthermore, the shape of the blade allows it contact to the surface of the thickened visceral pericardium in a parallel method. Therefore, the blade can cut the thickened pericardium at constant depth. This knife can be used more safely and comfortably than other devices to perform the Waffle procedure, despite of which there is no published report on its clinical use. We have used this device for three patients and their postoperative cardiac functions were improved. Moreover, we have not yet encountered any bleeding or coronary artery damage. We consider that the use of the vessel knife D 500 for the Waffle procedure is a very effective and safe method.

The use of the vessel knife D 500 for the Waffle procedure is a very effective and safe method. It has caused no myocardial or coronary injury therefore there has been no unexpected bleeding.

1. Sagristà-Sauleda J, Angel J, Sànchez A, Permanyer-Miralda G, Soler-Soler J. Effusive-constrictive pericarditis. N Engl J Med 2004 Jan 29;350(5):469–75.   [CrossRef]   [Pubmed]    
2. Yamazaki K, Marui A, Nakahara T, et al. Advanced effusive-constrictive pericarditis rescued by the aggressive waffle procedure. Gen Thorac Cardiovasc Surg 2012 May;60(5):297–301.   [CrossRef]   [Pubmed]    
3. Heimbecker RO, Smith D, Shimizu S, Kestle J. Surgical technique for the management of constrictive epicarditis complicating constrictive pericarditis (the waffle procedure). Ann Thorac Surg 1983 Nov;36(5):605–6.   [CrossRef]   [Pubmed]    
4. Kim JS, Ha JW, Im E, et al. Effects of pericariectomy on early diastolic mitral annular velocity in patients with constrictive pericarditis. Int J Cardiol 2009 Mar 20;133(1):18–22.   [CrossRef]   [Pubmed]