Controversial Protamine in Dealing with Acute Cardiac Tamponade During Radiofrequency Ablation
Radiofrequency catheter ablation (RFCA) is a widely used procedure for treating cardiac arrhythmias, including atrial fibrillation (AF) and premature ventricular contractions. Despite its efficacy, RFCA is not without risks, and acute cardiac tamponade is one of the most serious and life-threatening complications that can occur during the procedure. Acute cardiac tamponade is characterized by the rapid accumulation of blood in the pericardial cavity, which compresses the heart and leads to a deterioration of systemic circulation. Emergency percutaneous pericardiocentesis and immediate autologous blood transfusion are essential interventions in such cases. However, the administration of protamine to neutralize heparin and control bleeding remains controversial, as it may lead to the formation of pericardial blood clots, potentially necessitating thoracotomy. This article aims to discuss the necessity and optimal timing of protamine administration and explore strategies to prevent blood clot formation during the management of acute cardiac tamponade during RFCA.
The study retrospectively analyzed the medical records, procedural details, and imaging materials of 1,826 patients who underwent RFCA at a single institution between April 2014 and June 2020. All patients provided written informed consent, and the study was approved by the local Institutional Committee on Human Research. The procedures were performed according to standard practices, with a decapolar catheter positioned in the coronary sinus and a quadripolar catheter placed in the right ventricle or right atrium. Transseptal puncture was performed for AF cases, and a three-dimensional depiction of the heart was constructed using the Carto 3 or EnSite NavX systems. Open-irrigation ablation catheters were used, and pulmonary vein isolation was achieved for paroxysmal AF, with additional line blocks of the left atrial roof and mitral isthmus for persistent AF. Left atrial appendage plugging devices were implanted in patients with paroxysmal AF complicated by cerebral infarction. Systemic heparinization was implemented in all patients undergoing left-sided heart catheterization, with the initial dose based on patient weight and additional doses adjusted according to activated clotting time.
Acute cardiac tamponade was suspected in cases of severe chest pain, loss of consciousness, decreased blood pressure and oxygen saturation, and the sound of a steam pop during RFCA. Fluoroscopy was used to confirm the diagnosis by observing reduced cardiac silhouette excursion in the left anterior oblique view. Transthoracic echocardiography (TTE) and intracardiac echocardiography were also employed to monitor the pericardium in real time. When cardiac tamponade was confirmed, emergency subxiphoid pericardial puncture was performed under fluoroscopic guidance, and a six-French ventriculography pigtail catheter was introduced to drain the blood. The salvaged blood was rapidly reinfused via the femoral venous sheath after simple filtration. Protamine was administered to neutralize heparin, and homologous blood transfusion was prepared if necessary. Most cases of cardiac tamponade were managed conservatively, but patients with unstable or collapsed hemodynamics were transferred to the operating room for emergency thoracotomy.
Among the 1,826 patients, 12 (0.66%) experienced acute cardiac tamponade during RFCA. The mean age of these patients was 67 ± 5 years, and half were male. RFCA was performed for AF in 10 patients (8 with paroxysmal AF and 2 with persistent AF) and for premature ventricular contractions in 2 patients. Left atrial appendage plugging devices were implanted in 3 patients with paroxysmal AF and prior cerebral infarction. Steam pop occurred in 5 cases, and mechanical injury occurred in 7 cases during catheter manipulation. Perforations were located in the left atrium (7 cases), left ventricle (1 case), right ventricle (3 cases), and coronary sinus (1 case). The average volume of pericardial drainage was 1,018 ± 742 mL (range: 250–2,500 mL). Autologous transfusion was performed in 10 patients, with an average reinfusion volume of 932 ± 774 mL (range: 230–2,500 mL).
Protamine was administered in 9 patients to reverse heparin anticoagulation. In 5 of these patients, blood could no longer be aspirated after protamine administration, and fluoroscopy showed the disappearance of cardiac silhouette excursion during strong contraction, suggesting the formation of blood clots. Contrast medium injected into the pericardial cavity spread in a patchy manner, indicating clot formation. These patients experienced a sharp drop in blood pressure and oxygen saturation, loss of consciousness, and whole-body sweating, necessitating emergency thoracotomy. Massive blood clots were found in the pericardial cavity during surgery, and all patients survived and were discharged within 10 days.
The incidence of acute cardiac tamponade during RFCA is consistent with prior reports, and it remains one of the most frequent fatal complications of arrhythmia ablation. Timely recognition and prompt pericardiocentesis are crucial for reducing mortality. Signs of cardiac tamponade include an abrupt decrease in blood pressure and oxygen saturation, severe chest pain, loss of consciousness, and excessive sweating. Fluoroscopy is a valuable tool for early detection, especially in electrophysiology laboratories without TTE equipment. Intracardiac echocardiography offers advantages in monitoring the pericardium in real time and can detect effusion immediately after catheter manipulation.
The volume of spontaneous bleeding depends on the size, location, and geometric configuration of the perforation, intra-cavity pressure, and the level of anticoagulation. The largest volume of blood loss occurred due to steam pop at the anterior septum of the right ventricular outflow tract. Autologous blood transfusion is an effective method for maintaining hemodynamic stability, despite potential complications such as microembolisms, sepsis, and thrombosis. This technique is characterized by its availability, flexibility, and safety.
The administration of protamine to neutralize heparin is intended to promote local thrombus formation and stop bleeding. However, in some cases, protamine may lead to hypercoagulable blood accumulating in the pericardial cavity, forming massive clots that exacerbate cardiac tamponade and necessitate emergency thoracotomy. The timing of protamine administration and the prevention of blood clots are critical. Protamine should be administered only after most of the blood has been drained from the pericardial cavity, and continuous observation is necessary for recurrent or persistent bleeding. Injecting heparin saline into the pericardial cavity can neutralize protamine and prevent clot formation, and using a thicker sheath (10-French to 12-French) instead of a six-French pigtail catheter can facilitate the drainage of massive blood clots. These measures may help manage acute cardiac tamponade conservatively in most cases.
In conclusion, while protamine is commonly used to reverse heparin anticoagulation during the management of acute cardiac tamponade during RFCA, its administration may lead to the formation of blood clots, exacerbating the condition and necessitating emergency thoracotomy. Careful consideration of the timing of protamine administration and the implementation of strategies to prevent clot formation are essential for improving patient outcomes.
doi.org/10.1097/CM9.0000000000001601
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