P035: HEMODYNAMIC INSTABILITY DURING HISTOTRIPSY
Sofia Cartaya, MD; Kevin Bennett, MD; Cameron Howard, MD; Benjamin Houseman, MD
Memorial Healthcare System
Introduction: Histotripsy is a form of non-thermal tissue ablation that utilizes high-intensity ultrasound to liquefy solid tumors through cavitation (Figure 1). These liquefied masses are later cleared by the immune system. [1] Histotripsy is very precise in targeting lesions, but there is a theoretical potential to impact the heart when lesions are adjacent to the cardiac surface. [2] Here we describe a case of profound hypotension and bradycardia during histotripsy ablation of a segment IVa hepatic metastasis in a 79-year-old man with underlying rhythm abnormalities.
Case Report: A 79-year-old male patient with a history of significant for tachy-brady syndrome on propafenone, hypertension on amlodipine, atrial fibrillation, and metastatic lung cancer to the liver and bone presented for histotripsy of liver metastasis. His preoperative PET CT scan revealed a 1.7-cm lesion in the left liver segment IVa (Figure 2), a 1.5-cm lesion in liver segment VIII, and a 1.9-cm lesion in liver segment VI. Baseline laboratory studies were within normal limits.
General anesthesia was induced and his airway was secured with a 37F left-sided double-lumen endotracheal tube to permit left lung ventilation. Histotripsy was initially targeted to the 1.7 cm segment IVa lesion. During initial targeting, the patient became hypotensive and bradycardic. Given his underlying conduction disease, ablation of this lesion was aborted. Histotripsy was subsequently performed on lesions in segments VIII and VI without further hemodynamic compromise.
Discussion / Conclusion: Histotripsy permits management of hepatic lesions that were previously considered inoperable and carries fewer risks than hepatectomy. While this procedure has a strong record of safety, risks associated with general anesthesia and lung isolation remain.
This case describes hypotension and bradycardia during histotripsy of a lesion in hepatic segment IVa, which is in close proximity to the heart (Figure 2). To our knowledge, no cases of histotripsy-induced arrhythmia have been reported. While it is possible that histotripsy for this lesion did impact the adjacent cardiac tissue, we feel that it is unlikely given the precision of this technique. We suspect that the patient’s underlying cardiac conduction disease may have contributed to the observed bradycardia. [3] Clinicians should consider augmented monitoring, anticipate need for hemodynamic support, and be willing to discontinue the procedure when challenges arise.
We note that focused ultrasound is gaining traction for both modulation of conduction in cardiac arrhythmias and deliberate tissue destruction of infarcted myocardium. [3]
References
[1] doi: 10.1080/02656736.2021.1905189.
[2] doi: 10.1109/TUFFC.2012.2506
[3] doi: 10.1080/17434440.2016.1217772.
[5] https://clinicalpub.com/segmentoriented-anatomic-liver-resections-indications-and-outcomes/