What is the waffle procedure for refractory constrictive pericarditis?

What is the Waffle Procedure for Pericarditis?

The waffle procedure is a specialized surgical technique used to treat refractory constrictive pericarditis when standard pericardiectomy fails to relieve epicardial (visceral pericardial) constriction—it involves making multiple crosshatched incisions into the thickened, fibrotic epicardium to allow the myocardium to re-expand and restore diastolic function. 1, 2

Mechanism and Rationale

The waffle procedure addresses a critical limitation of conventional pericardiectomy: residual epicardial constriction prevents adequate hemodynamic improvement even after complete removal of the parietal pericardium. 1 This occurs because:

• The visceral layer of the pericardium (epicardium) becomes fibrotic and constricts the heart independently of the parietal layer, particularly in effusive-constrictive pericarditis where the visceral component is primarily responsible for constriction 3, 4
• Standard pericardiectomy removes only the parietal pericardium, leaving the constricting epicardial layer intact 2, 5
• The constrictive physiology depends mainly on the visceral layer, so removing parietal tissue alone may not restore normal cardiac function 4

Surgical Technique

The procedure is performed through the following steps:

• Complete radical pericardiectomy is performed first via median sternotomy to remove all accessible parietal pericardium 2, 5
• Multiple longitudinal and transverse incisions are then made in a crosshatched pattern on the thickened epicardium, creating a waffle-like appearance on the epicardial surface 1, 2, 5
• Incisions are carefully placed to avoid major coronary artery branches and penetration into the myocardium 5
• The left ventricle is typically addressed first, followed by the right ventricle 2
• Modern techniques use an ultrasonic scalpel or electrocautery unit rather than sharp dissection, with continuous ECG monitoring for arrhythmias 1, 2
• An apical suction device (similar to off-pump CABG techniques) helps lift and stabilize the heart during the procedure 2

When the Waffle Procedure is Indicated

The waffle procedure should be performed in patients with constrictive pericarditis who have documented epicardial constriction that will not be relieved by pericardiectomy alone. This includes:

• Effusive-constrictive pericarditis, where visceral pericardiectomy must be performed because the visceral layer constricts the heart 3
• Cases where intraoperative assessment reveals persistent constriction after parietal pericardiectomy 6, 5
• Patients with rapid progression from pericardial effusion to pericardial thickening with persistent elevated right heart pressures after pericardiocentesis 6

Technical Considerations and Pitfalls

The procedure can be performed without cardiopulmonary bypass (off-pump) in most cases, though on-pump beating-heart surgery may be necessary in advanced cases 2, 6. Key technical points include:

• Sharp dissection of the epicardium into small fragments must continue until visible improvement in ventricular motion is observed 3, 6
• The visceral component of pericardiectomy is technically difficult and requires meticulous technique to avoid myocardial injury 3
• Continuous monitoring for arrhythmias is essential during epicardial incisions 1
• This surgery should only be performed at centers with extensive experience in pericardiectomy for constrictive pericarditis 3

Expected Outcomes

Remarkable hemodynamic improvement is typically obtained immediately after the procedure, with relief of constriction allowing the myocardium to re-expand and achieve adequate diastolic filling 2, 5. Patients who undergo successful waffle procedures:

• Experience resolution of right heart failure symptoms and can be discharged within 2-3 weeks 5
• Remain asymptomatic long-term with restoration of both diastolic and systolic function 4
• Face the same 6-12% operative mortality risk as standard pericardiectomy for constrictive pericarditis 3

Critical Warnings

Do not attempt the waffle procedure in patients with end-stage constrictive pericarditis (cardiac index <1.2 L/m²/min, cachexia, severe hypoalbuminemia, cardiogenic cirrhosis), as these patients derive little benefit and face prohibitively high operative mortality 3, 7. Referral to a high-volume center with pericardial disease expertise is mandatory, as the technical demands of visceral pericardiectomy exceed those of standard cardiac surgery 3.