Efficacy of low-energy T wave shocks for induction of ventricular fibrillation in patients with implantable cardioverter defibrillators.

The efficacy of low-energy T wave shocks for induction of ventricular fibrillation (VF) was evaluated in 33 patients undergoing implantable cardioverter defibrillator (ICD) implantation (33 sessions) or predischarge ICD testing (20 sessions). To induce VF, the ventricle was paced for eight cycles at a 400-ms cycle length (S1-S1), and the T wave was scanned with a monophasic shock (S2) delivered via the defibrillating lead system. Of 294 attempts, the T wave shocks induced VF in 65%, nonsustained ventricular tachycardia in 10%, and less than five ventricular beats in 25%. As compared with the failed T shocks, the mean energy of successful T wave shocks was higher and the S1-S2 coupling interval was shorter. When the S2 timing was examined in relation to the T wave peak, the VF induction efficacy was 37% for shocks delivered more than 70 ms before the T wave peak, 82% for shocks delivered 30-70 ms before the T wave peak, and 50% for shocks delivered less than 30 ms before or just after the T wave peak (P < .001). Thus, in patients undergoing ICD implantation or ICD conversion testing, the use of low-energy T wave shocks is an effective and safe method to provoke VF.

Reoperation, emergency and urgent open cardiac surgery in Jehovah's Witnesses.

Progressive advances in perfusion technology and perioperative supportive management have made it possible for members of the Jehovah's Witnesses religious group to undergo open cardiac operations with remarkable safety. However, hospital mortality remains high in (1) patients requiring reoperation (in whom both technical and bleeding problems tend to be more frequent) and (2) patients with significantly compromised cardiac performance requiring urgent or emergency operation. Employing a number of perioperative measures designed to minimize blood loss and maintain hematocrit levels (including use of the recently available recombinant human erythropoietin in two patients whose cases are reported herein), 13 reoperations and five urgent or emergency operations were performed. The one death in the entire series occurred in a patient (reoperation group) who died of a cerebrovascular accident of presumed embolic etiology, having undergone combined debridement of a stenotic heavily calcified aortic valve and a second coronary artery revascularization procedure. None of the patients required surgical exploration for bleeding. We suggest that currently available methodology permits Jehovah's Witnesses to undergo reoperation, emergency surgery, or urgent open cardiac operation at a level of risk not dissimilar to that seen in patients who permit use of homologous blood and products in their treatment.

Clinical and electrophysiologic determinants, treatment and survival of patients with sustained malignant ventricular tachyarrhythmias occurring late after myocardial infarction.

To assess the clinical and electrophysiologic determinants, treatment and survival of patients with sustained malignant ventricular tachyarrhythmias late after myocardial infarction, a total of 108 patients (mean age 61 +/- 10 years) were studied. Thirty-two patients (Group I) had sustained ventricular tachyarrhythmias 8 to 60 days (mean 13 +/- 9) after acute myocardial infarction. The remaining 76 patients (Group II), who served as a control group, had no sustained ventricular tachyarrhythmias less than or equal to 60 days after infarction. The most significant independent determinants of sustained ventricular tachyarrhythmias late after infarction were the presence of late potentials (chi square = 16.07, p = 0.0001), defined as an abnormal signal-averaged QRS complex in association with an abnormal root-mean-square voltage in the terminal 40 ms of the QRS complex, and an abnormal ejection fraction of less than 40% (chi square = 10.09, p = 0.001). Sustained ventricular tachycardia was induced in 27 (96%) of 28 Group I patients. Among the 32 patients in Group I, antitachycardia therapy included antiarrhythmic drug therapy as the sole preventive measure in 14 (44%); map-guided surgery or coronary artery bypass surgery, or both, in 14 (44%) and the automatic cardioverter-defibrillator in 4 (12%). The arrhythmias were rendered noninducible in 83% of patients after map-guided surgery and in 41% after drug therapy. During a follow-up period of 20 +/- 14 months, five Group I patients (15%) had an arrhythmic event and four (9.3%) had a cardiac-related death. All five patients who had an arrhythmic event were receiving antiarrhythmic drug therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Aortic valve tumor: an unusual cause of coronary obstruction during cardiac catheterization.

Coronary artery obstruction during cardiac catheterization is a rare but serious complication that has been reported to occur in 0.15 to 0.5% of cases. The most common causes of intraprocedural coronary occlusion include thromboembolism, air embolism, and coronary dissection. This report describes the angiographic findings of a patient who developed chest pain with electrocardiographic evidence of myocardial ischemia due to obstruction of the right coronary artery by an aortic valve tumor.

A comparative analysis of signal averaging of the surface QRS complex and signal averaging of intracardiac and epicardial recordings in patients with ventricular tachycardia.

To test the hypothesis that late potentials may be more enhanced by signal processing of intracardiac and epicardial electrograms, we performed a comparative analysis of signal averaging (SA) of the surface QRS complex (method I), signal averaging of an endocardial electrode catheter recording (method II), and epicardial recording (method III) in 24 patients (mean age = 55 +/- 14 years). Sixteen of the 24 patients (66%) had spontaneous as well as induced sustained ventricular tachycardia (VT), whereas the remaining 8 patients (33%) had spontaneous non-sustained VT. SA by the three methods was performed within less than or equal to 24 hours of each other, utilizing a band pass filter frequency of 25 to 250 Hz. The duration of the SA-QRS complex, low amplitude signals (LAS) of less than 40 microV and the RMS-voltage (V) of the terminal 40 ms were determined for the three methods. There was a significant correlation between method I and methods II and III for the SA-QRS duration (r = .928, p less than .001), RMS-V (r = .634, p less than .002) and LAS (r = .783, p less than .001). There was no significant difference in the quantitative signal-averaged parameters between the three methods. The incidence of the RMS-V of less than 25 microV (37.5% vs 21%); LAS of greater than 32 ms (46% vs 37.5%) and SA-QRS of greater than 120 ms (54% vs 42%) was higher but statistically non-significant by methods II and III when compared to method I. We concluded that: (1) SA of intracardiac electrograms correlate well with SA of the surface QRS. This observation further validates the technique of surface SA to detect delayed ventricular activation. (2) SA of intracardiac electrograms may provide additional information on quantitative SA parameters relative to surface QRS in some patients with VT.

Accidental placement of the Greenfield filter in the heart: report of two cases.

The Greenfield filter has become the most popular device for interruption of the inferior vena cava; however, a potential for lethal complications exists. We report two cases in which this filter was accidentally released in the heart. To avoid this problem, it is recommended that the guide wire be positioned in the inferior vena cava before the introducer is inserted into the venous system.

Left ventricular to left atrial communication secondary to a paraaortic abscess: color flow Doppler documentation.

Aortic root abscess occurs frequently in aortic prosthetic valve infective endocarditis. The present echocardiographic report documents a ruptured abscess that led to a direct communication between the left ventricular outflow tract and the left atrium confirmed by real-time (color flow) Doppler imaging.

Intralobar pulmonary sequestration: MR evaluation.

This report documents the use of magnetic resonance (MR) in evaluation of intralobar pulmonary sequestration. Because of its distinctive multiplanar capabilities and nonreliance on contrast media to visualize blood vessels, MR can be used to define and characterize the size and course of anomalous arterial feeding vessels. Furthermore, MR can be of value in detecting the presence of mucoid-impacted bronchi within abnormal segments of the lung. It is concluded that in select cases MR may obviate the need for more invasive procedures to establish the diagnosis of pulmonary sequestration.

Ostial left main stenosis following repair of a ruptured sinus of Valsalva aneurysm.

A patient complained of angina pectoris nine months after surgical repair of an aortic right atrial fistula and mitral valve replacement. Subsequently, he was shown to have a new obstruction of the ostium of the left main coronary artery. This case illustrates the need to consider this syndrome in the differential diagnosis of postoperative complaints of chest pain, especially following an operation which involves direct cannulation of the coronary arteries.

Myopotential interference with DDD pacemakers: endocardial electrographic telemetry in the diagnosis of pacemaker-related arrhythmias.

Skeletal myopotentials may inhibit the output of unipolar demand ventricular pacemakers, resulting in protracted episodes of asystole in susceptible patients. The new DDD-mode pacemakers have, in addition to a unipolar ventricular lead, a unipolar atrial lead to enable atrioventricular sequential or atrial synchronous function. During clinical investigation of a new dual-unipolar cardiac pacing system programmed to operate in the DDD mode (Pacesetter AFP models 281 and 283), 6 patients were noted (5 men and 1 woman, aged 22 to 68 years) who manifested paroxysmal acceleration of ventricular pacing rate approaching the maximal tracking rate. Two patients also had abrupt slowing or cessation of ventricular output. With the use of atrial electrographic recordings (obtained with telemetry), the following mechanisms of rate change were found: myopotential tracking, myopotential inhibition, interference-mode asynchronous operation, sudden increases in sinus rate, and pacemaker-mediated reentrant tachycardia. In all patients, reprogramming of the implanted devices, based on telemetered atrial electrography, resulted in disappearance of the arrhythmias and loss of symptoms while maintaining the DDD pacing mode. Thus, several mechanisms of rhythm disturbances are peculiar to dual-chamber cardiac pacing systems that use unipolar electrodes. Endocardial telemetry combined with extensive programming capability offers the best opportunity for proper diagnosis and management of these problems.

Primary sick sinus syndrome as an indication for chronic pacemaker therapy in young adults: incidence, clinical features, and long-term evaluation.

Of 1484 pacemakers placed at our institution between 1970 and 1980, there were 18 patients between the ages 20 and 40 years who were not postoperative congenital heart disease cases. Twelve of these patients had primary sick sinus syndrome (SSS) as the indication for pacing. Eleven of 12 patients were markedly symptomatic with syncope, near syncope, or lightheadedness. Ambulatory monitoring revealed evidence of sinus node disease in all patients studied. Electrophysiologic studies were falsely negative in the five patients in whom they were performed. Patients tolerated pacemaker therapy well and became asymptomatic with pacing. We conclude that SSS in young adults is uncommon, but still represents the most common indication for permanent pacemaker therapy in this age group. The decision for pacemaker therapy should depend on symptoms and results of ambulatory monitoring. These patients can expect symptomatic improvement with pacing.

Administering cold cardioplegia in patients undergoing coronary artery bypass grafting.

In patients undergoing coronary artery bypass grafting (CABG), use of hypothermic cardioplegia for myocardial protection may not always achieve even cooling in the areas distal to a severely obstructed artery. Employing simultaneous myocardial temperature measurements, we documented "warm" areas in some patients having CABG. We then devised a technique of combined aortic root and intracoronary cardioplegic infusion. This has achieved prompt cooling of the warm areas and has resulted in uniform myocardial temperatures of 5 degrees to 8 degrees C.