Coronary sinus as a site for stable temporary atrial pacing to tide over premature ventricular complex-triggered recurrent ventricular fibrillation in a patient with severe left ventricular dysfunction after coronary bypass surgery

Anesthetic management of a patient with preoperative R-on-T phenomenon undergoing laparoscopic-assisted sigmoid colon resection: A case report

BACKGROUND

The R-on-T phenomenon is a malignant arrhythmia associated with potentially catastrophic consequences. It may initiate ventricular tachycardia or ventricular fibrillation, which can result in syncope or sudden cardiac death. This manifestation poses a great challenge for anesthesiologists. However, it is rarely encountered in the perioperative setting.

CASE SUMMARY

We herein present a case in which the R-on-T phenomenon was incidentally revealed by 24-h Holter monitoring in a patient diagnosed with sigmoid colon cancer. Careful evaluation and treatment with mexiletine were carried out preoperatively under consultation with a cardiovascular specialist, and surgery was uneventfully performed under general anesthesia after thorough preparation.

CONCLUSION

Physicians should be vigilant about this infrequent but potentially fatal arrhythmia. Our experience suggests that the anesthetic process can be greatly optimized with careful preparation.

Surgical Ablation of Cardiac Tissue with Nanosecond Pulsed Electric Fields in Swine

BACKGROUND

Myocardial tissue can be ablated by the application nanosecond pulsed fields (nsPEFs). The applied electric fields irreversibly permeabilize cell membranes and thereby kill myocytes while leaving the extracellular matrix intact.

METHODS

In domestic pigs (n = 10), hearts were exposed via sternotomy and either ablated in vivo ([Formula: see text] = 5) or in excised, Langendorff-perfused hearts ([Formula: see text] = 5). The nsPEFs consisted of 6-36 pulses of 300 ns each, delivered at 3-6 Hz; the voltage applied varied from 10 to 12 kV. Atrial lesions were either created after inserting the bottom jaw of the bipolar clamp into the atrium via a purse string incision (2-3 lesions per atrium) or by clamping a double layer of tissue at the appendages (one lesion per atrium). Ventricular lesions were created after an incision at the apex. The transmurality of each lesion was determined at three points along the lesion using a triphenyl tetrazolium chloride (TTC) stain.

RESULTS

All 27 atrial lesions were transmural. This includes 13/13 purse string lesions (39/39 sections, tissue thickness 2.5-4.5 mm) and 14/14 appendage lesions (42/42 sections, tissue thickness 8-12 mm). All 3 right ventricular lesions were transmural (9/9 sections, 18 pulses per lesion). Left ventricular lesions were always transmural for 36 pulses (3/3 lesions, 9/9 sections). All lesions have highly consistent width across the wall. There were no pulse-induced arrhythmias or other complications during the procedure.

CONCLUSIONS

nsPEF ablation reliably created acute lesions in porcine atrial and ventricular myocardium. It has far better penetration and is faster than both radiofrequency ablation and cryoablation and it is free from thermal side effects.

Temporary coronary sinus pacing to improve ventricular dyssynchrony with cardiogenic shock: A case report

BACKGROUND

Temporary transvenous pacing through the coronary sinus is a novel approach rarely used in treating unstable bradycardia. This modality could provide cardiac pacing while achieving better ventricular synchrony. We present a case who received cardiac pacing through the coronary sinus and provide a summary of evidence in the current literature.

CASE SUMMARY

A 55-year-old woman with a history of advanced heart failure was admitted to the rehabilitation ward after a recent stroke. During hospitalization, she had paroxysmal atrial fibrillation with rapid ventricular response resulting from fluid overload. While atrial fibrillation was spontaneously reversed to sinus rhythm after diuresis, she developed multiple episodes of polymorphic ventricular tachycardia along with sinus bradycardia and prolonged QTc interval. She became hypotensive despite appropriate medical management. Pacing through her implantable cardioverter-defibrillator was attempted but worsened her hypotension. Ventricular dyssynchrony was suspected. Temporary transvenous atrial pacing through the coronary sinus was performed, which stabilized her blood pressure and improved end-organ perfusion. A permanent biventricular pacemaker was later implanted, and she was safely discharged to a nursing home.

CONCLUSION

Temporary transvenous pacing through the coronary sinus, a novel approach to treat unstable bradycardia, may reduce ventricular dyssynchrony.