Capecitabine-induced-coronary-vasospasm leading to polymorphic ventricular tachycardia and cardiac arrest.

Capecitabine, a pro-drug of 5-fluorouracil, is commonly used in the treatment of breast and colorectal cancer. Its side effects, including nausea, vomiting, diarrhea, fatigue, loss of appetite, and bone marrow suppression, are well recognized. However, coronary vasospasm represents a less commonly recognized but significant complication of fluoropyrimidine-based therapies such as capecitabine. Proposed mechanisms for this adverse effect complication include direct endothelium-independent vasoconstriction, activation of protein kinase C, and activation of the cyclooxygenase pathway. In this report, we present a case of capecitabine-induced coronary vasospasm leading to progressive, focal ST-elevations, myocardial ischemia, and subsequently polymorphic ventricular tachycardia. These events were captured on telemetry, in a male in his early 40s, diagnosed with stage IIIB sigmoid colon cancer. Notably, the patient had no pre-existing coronary artery disease or other cardiovascular risk factors. Upon diagnosis, the patient was initiated on a calcium channel blocker, verapamil, to mitigate further coronary vasospasm events. After thorough discussions that prioritized the patient's input and values, an implantable cardioverter-defibrillator was placed subcutaneously. Following discharge, the patient restarted capecitabine therapy along with verapamil prophylaxis and did not experience any subsequent shocks from his ICD as assessed during his outpatient follow-up visits. This case emphasizes the need to involve patients in decision-making processes, especially when managing unexpected and serious complications, to ensure treatments align with their quality of life and personal preferences.

Investigation of the Utility of the Audible Alert in Recent Generation Medtronic Implantable Cardioverter Defibrillators.

BACKGROUND: Medtronic implantable cardioverter defibrillators (ICDs; Medtronic Inc., Mounds View, MN, USA) are equipped with Patient Alert™, a feature in which the ICD generator emits a series of audible tones to notify patients of possible system malfunction. A prior study of this issue revealed that only 50% of patients with older Medtronic devices were able to hear alerts. More recently, Medtronic has incorporated modifications to the alert. Therefore, we studied how frequently alert tones emitted by the current generation of Medtronic ICDs are audible by patients. METHODS: A series of patients were evaluated in an outpatient ICD clinic. Alert tones were demonstrated using a device programmer in a quiet room and in the presence of low-level background noise. Patients reported whether they heard the tones, and they completed questionnaires regarding the tones. RESULTS: The total sample size was 100 patients, 81 male, who ranged from 29 years to 94 years of age (mean age 72.1 ± 11.8). Among the study subjects, 46% were older than 75 years, 41% were between 55 years and 75 years, and 13% were younger than 55 years. In the absence of background noise, 94% of patients were able to hear both alerts, 1% heard only one alert, and 5% heard neither. In the presence of background noise, 88% of patients heard both the alerts, 7% heard only one alert, and 5% heard neither alerts. CONCLUSIONS: Our results demonstrate that alert tones in recent generation Medtronic ICDs have improved audibility, compared to prior published data, among a large outpatient ICD population.

Alert tones are frequently inaudible among patients with implantable cardioverter-defibrillators.

BACKGROUND: Current management guidelines for patients with Medtronic Sprint Fidelis ICD leads (Medtronic Inc., Minneapolis, MN, USA) include prominent use of Patient Alert, a feature in which the ICD generator emits audible beeps at two programmable frequencies. Because hearing loss is highly prevalent beyond the sixth decade of life, the utility of this feature is unclear. Therefore, we conducted a survey of patients' ability to hear the Medtronic Patient Alert. METHODS: During visits to an outpatient device clinic, patients with Medtronic ICDs were evaluated for their ability to hear ICD tones. RESULTS: The patient group consisted of 102 patients. Patients older than 70 years comprised 68% of the sample, with 16% between 60 and 70, and 17% younger than 60 years. Of the 102 patients, 59% (56% of males and 70% of females) were able to hear at least one tone. Ability to hear ICD tones decreased with advancing age. Among patients over 60 and 70 years, 52% and 43%, respectively (P < 0.001 vs. patients below 60 and 70 years), could hear at least one tone. CONCLUSIONS: The Patient Alert feature is not useful among a large proportion of ICD patients. Patients with Sprint Fidelis leads should be evaluated for their ability to hear audible ICD tones. For patients who cannot hear the Patient Alert feature, a wireless remote monitoring and/or daily application of a magnet by a caregiver should be considered. Device manufacturers should include nonauditory alert technologies such as wireless remote monitoring and vibratory stimulation in future devices.

Continuous nonfluoroscopic localization of the esophagus during radiofrequency catheter ablation of atrial fibrillation.

INTRODUCTION: Atrial-esophageal fistula formation is a dreaded complication of radiofrequency catheter ablation for atrial fibrillation. Esophageal localization is of potential value in avoiding lesion placement where the left atrium is juxtaposed to the esophagus. METHODS AND RESULTS: Twenty-seven patients underwent 33 pulmonary vein encirclement procedures. All the patients received general anesthesia with inhalational agents and either a fenestrated laryngeal mask airway or an endotracheal tube. A diagnostic electrophysiologic catheter was inserted into the esophagus, and a virtual esophageal tube was created using an electroanatomic mapping system. In all cases, the catheter was placed without difficulty and satisfactory virtual esophageal images were created. The catheter remained in the esophagus until the end of each ablation procedure. Esophageal catheter location during and after the ablation was compared with the initial location. Areas of close proximity between the left atrium and esophagus were easily identified. Change in esophageal location was not observed. Identification of esophageal proximity to the pulmonary veins allowed for identification of high-risk cases. In such cases, the planned procedure was modified to avoid esophageal injury (12 of 27 patients). CONCLUSIONS: (1) Real-time localization of esophageal position using a nonfluoroscopic mapping system during atrial fibrillation ablation is safe, practical, and straightforward. (2) Among patients who receive general anesthesia, esophageal position appears to be static, suggesting that one initial virtual image is sufficient for the duration of an ablation procedure.

Use of the retained guidewire technique facilitates left ventricular epicardial capture during biventricular defibrillator implantation.

We report a case of biventricular implantable cardioverter-defibrillator (ICD) insertion in which standard lead placement techniques could not achieve left ventricular capture. Protrusion of the guidewire beyond a venous stenosis provided adequate left ventricular capture.

Why a sawtooth? Inferences on the generation of the flutter wave during typical atrial flutter drawn from radiofrequency ablation.

BACKGROUND: Typical atrial flutter (AFL) is a macroreentrant arrhythmia characterized by a counterclockwise circuit that passes through the cavotricuspid isthmus with passive depolarization of the left atrium. These electrical events are thought to be responsible for the classic "sawtooth" wave of atrial flutter seen on the surface electrocardiogram characterized by a gradual downward deflection followed by a sharp negative deflection. It has been suggested that the negative flutter wave is a result of passive depolarization of the left atrium. We hypothesized that interruption of the circuit within the isthmus would prevent the reentrant wave from depolarizing the left atrium thus eliminating the component of the electrocardiogram reflecting left atrial depolarization. METHODS: We examined 100 cases of atrial flutter with the typical "sawtooth" pattern referred for radiofrequency ablation. Ninety-seven of the 100 were successfully ablated. All cases were reviewed for termination of atrial flutter with the last intracardiac electrogram just lateral to the site of linear ablation and surface flutter wave at the moment of termination not obscured by the QRS segment or the T-wave. Seventeen of the 97 met these criteria. RESULTS: Seventeen of the 17 cases demonstrated a gradual negative deflection as the last discernible wave of atrial activity followed by an isoelectric period and resumption of normal sinus rhythm. The last generated wave lacked the sharp negative downstroke. CONCLUSION: These results suggest that the sharp negative deflection of flutter waves likely correlates with the wavefront's penetration of the interatrial septum and passive depolarization of the left atrium.

Cardiac vein angioplasty for biventricular pacing.

Biventricular pacing for the treatment of congestive heart failure has consistently demonstrated improvement in quality-of-life and reduction in heart failure symptoms. Though the over-the-wire systems will be helpful in overcoming many existing obstacles to optimal lead placement, anatomic variability will still limit overall success. Cardiac vein angioplasty may be required for deployment of leads into tortuous or obstructed cardiac veins. This case report describes the angioplasty of a focal cardiac vein stenosis allowing for successful implantation of a left ventricular pacing lead. The safety of this procedure is unknown, though the risks may be acceptable in certain patients.