William G. Stevenson

2012 ACCF/AHA/HRS focused update incorporated into the ACCF/AHA/HRS 2008 guidelines for device-based therapy of cardiac rhythm abnormalities: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines and the Heart Rhythm Society.

Developed in Collaboration With the American Association for Thoracic Surgery and Society of Thoracic Surgeons nnAndrew E. Epstein, MD, FACC, FAHA, FHRS, Chair ; John P. DiMarco, MD, PhD, FACC, FHRS; Kenneth A. Ellenbogen. MD, FACC, FAHA, FHRS; N.A. Mark Estes III, MD, FACC, FAHA, FHRS; Roger A.

2012 ACCF/AHA/HRS Focused Update of the 2008 Guidelines for Device-Based Therapy of Cardiac Rhythm Abnormalities

Developed in Collaboration With the American Association for Thoracic Surgery, Heart Failure Society of America, and Society of Thoracic Surgeons

Poor survival of patients with idiopathic cardiomyopathy considered too well for transplantation

Although the success of cardiac transplantation has encouraged earlier referral of potential candidates, those with mild symptoms of heart failure are frequently considered too well for transplantation. Outcome was investigated for 28 patients with non-ischemic dilated cardiomyopathy and ejection fraction of 25 percent or less who were denied transplantation due to lack of severe symptoms. One-year survival without transplantation was 46 percent. Low stroke volume and history of ventricular arrhythmias were independent predictors of early mortality. High risk, defined as either stroke volume of 40 ml or less or history of ventricular arrhythmia, identified 13 of 14 patients who did not survive one year and only one of 12 one-year survivors (p less than 0.001). Low stroke volume predicted hemodynamic failure (p less than 0.05) whereas arrhythmic history predicted sudden death (p less than 0.001). Clinical status improved in only six patients, all of whom had symptom duration of seven or less months at initial evaluation (p less than 0.001). Thus, patients referred to transplantation for dilated cardiomyopathy with an ejection fraction of 25 percent or less have a poor prognosis even if symptoms are mild. Patients with high hemodynamic risk may require early transplantation, whereas those with high arrhythmia risk may require other aggressive therapy in order to avoid transplantation until symptoms become severe.

Transesophageal echocardiography during radiofrequency catheter ablation of ventricular tachycardia

Radiofrequency lesion formation requires stable catheter tip/endocardial contact. Energy delivery is limited when temperatures are > 100 degrees C due to coagulum formation at the catheter tip. Transesophageal echocardiographic imaging may be useful for monitoring catheter position and detecting boiling. Transesophageal echocardiographic images were recorded during production of 22 radiofrequency lesions in bovine myocardium in a saline bath. Lesion size, tissue temperature and appearance of echo contrast (bubbles) were assessed. In 11 patients, transesophageal echocardiography was used to guide catheter movement and detect boiling during radiofrequency ablation for ventricular tachycardia. In the tissue bath, the appearance of echo bubbles was associated with visual bubbling at the catheter tip, tissue temperatures > 60 degrees C and larger lesions (284 +/- 165 vs 30 +/- 54 mm3; p < 0.001). In humans, transesophageal images easily identified the catheter tip in either ventricle and enabled continuous observation of electrode-tissue contact during radiofrequency application. Transesophageal echocardiographic bubbles appeared in 59 of 217 radiofrequency applications (27%). Continued radiofrequency application after appearance of bubbles was followed by an increase in impedance. Prolonged placement of the probe in heavily sedated patients resulted in a mild sore throat, but no other complications. Transesophageal echocardiographic imaging enables continuous monitoring of catheter position during radiofrequency energy application. The abrupt appearance of echo bubbles indicates boiling and impending coagulum formation at the catheter tip.

Implantable defibrillators for high-risk patients with heart failure who are awaiting cardiac transplantation

The objective of this study was to assess the operative risk and efficacy of implantable defibrillators for preventing sudden death in patients with heart failure awaiting transplantation. The average waiting time for elective cardiac transplantation is 6 months to 1 year. Sudden cardiac death is the major source of mortality in outpatients in stable condition awaiting cardiac transplantation. The efficacy of implantable defibrillator therapy in this population is not established. We analyzed the operative risk, time to appropriate shock, and sudden death in 15 patients determined to be at high risk of sudden death who were accepted onto the outpatient cardiac transplant waiting list. Nonfatal postoperative complications occurred in two (13%) subjects with epicardial defibrillating lead systems and in none with transvenous lead systems. Defibrillation energies were 16 +/- 2 J versus 24 +/- 2 J with epicardial and transvenous lead systems, respectively. Sudden death free survival until transplantation was 93%. Most of the patients (60%) had an appropriate shock during a mean follow-up of 11 +/- 12 months. The mean time to an appropriate shock was 3 +/- 3 months. Hospital readmission was required in three (20%) subjects to await transplantation on an urgent basis. However, two of these subjects had received appropriate shocks before readmission. In selected patients at high risk for sudden death while on the outpatient cardiac transplant waiting list, the operative risk is low and adequate defibrillation energies can be obtained to allow implantable defibrillator placement. Most subjects will have an appropriate shock as outpatients before transplantation, and sudden death free survival is excellent.(ABSTRACT TRUNCATED AT 250 WORDS)

Monomorphic versus polymorphic ventricular tachycardia after coronary artery bypass grafting

Abstract The results of this study suggest that polymorphic VT occurring after coronary artery bypass grafting warrants a therapeutic approach targeted at treatment of myocardial ischemia.

952-28 Monomorphic versus Polymorphic Ventricular Tachycardia After Coronary Artery Bypass Grafting

We hypothesized that 1) ventricular tachycardia and fibrillation (VT/VF) developing after coronary artery bypass grafting (CABG) are due to either restoration of perfusion to a chronic infarction or to peri-operative ischemia/infarction and 2) that VT morphologic and electrophysiologic characteristics would depend upon which mechanism was causal. Records of 17 pts referred for electrophysiologic studies (EPS) whose first episode of VT/VF ocurred peri-operatively were compared to a control group of 119 consecutive CABG pts without VT/VF. Results Pts with VT/VF had more depressed pre-operative ejection fraction (0.32 vs 0.49, pxa0=xa00.0001) and a higher incidence of peri-operative myocardial infarction (MI) (47% vs 8%, pxa0=xa00.0001) compared to control pts. The majority of VT/VF pts (88%) had a zone of prior infarction and placement of a bypass graft to an occluded vessel occurred more frequently in these Subjects compared to controls (pxa0=xa00,03). The majority of pts having monomorphic VT (64%) did not suffer a peri-operative MI and 80% had inducible monomorphic VT at EPS. Only 37% of pts having polymorphic VT were inducible and 67% had a peri-operative MI. Conclusion New onset monomorphic VT after bypass surgery is associated with an old infarct scar and may, in some cases, be due to revascularization of an area of prior infarction. Polymorphic VT/VF is usually associated with acute ischemia/infarction.