Jorge Camunas

Complications arising after implantation of DDD pacemakers: the MOST experience.

The purpose of this study was to characterize the incidence, time course, frequency, and spectrum of acute and chronic complications arising from dual-chamber pacemaker implantation. This information may serve as a benchmark when comparing complication rates for dual-chamber pacemaker implantation with those for biventricular pacemaker implantation.

Predictors of Long-Term Survival in Patients With Malignant Ventricular Arrhythmias

The study consisted of 369 patients (age 62 +/- 13 years) who presented to our institution from April 1984 to April 1994 for malignant ventricular arrhythmias presenting as sustained ventricular tachycardia (VT) in 57% of patients, ventricular fibrillation in 25% of patients, and syncope due to VT in 17% of patients. Coronary artery disease was present in 74% of patients, cardiomyopathy in 19% of patients, and no evident heart disease in 7% of patients. Two hundred twenty-one patients were given drug, therapy, 47 patients underwent arrhythmia surgery, and 75 patients had an implantable cardioverter-defibrillator (ICD). During a mean follow-up of 30 months (range 1 to 101), 66 patients (18%) died from a cardiac death of which 26 (39%) were sudden. Cox regression analysis was conducted utilizing a total of 19 variables (clinical and therapeutic) in the entire population and separately in patients with coronary artery disease and cardiomyopathy. The most significant variables (multivariate analysis) of survival from cardiac mortality in the entire population were: congestive heart failure (CHF) class (p = 0.0003), ejection fraction (p = 0.02), and the use of drug therapy (p = 0.03); in patients with coronary artery disease, CHF class (p = 0.0001) and ejection fraction (p = 0.0006); and in patients with cardiomyopathy, CHF class (p = 0.009) and sustained VT on Holter monitoring (p = 0.007). Kaplan-Meier survival rates from cardiac death were: significantly lower (p = 0.005) in patients with CHF class III and IV compared with CHF class I and II (25% vs 58%, p = 0.005) with drug therapy; marginally significant (47% vs 88%, p = 0.06) from 20 to 40 months in patients with an ICD; and nonsignificant in patients who underwent arrhythmia surgery (63% vs 71%). Patients with an ICD had a better expected survival (82%) than patients who had arrhythmia surgery (69%) and drug therapy (65%). Thus, in patients with malignant ventricular arrhythmias, CHF class was the most significant independent predictor of survival from cardiac mortality over all disease substrates, and therapy influenced survival depending on the CHF class. Patients in CHF class III and IV who underwent arrhythmia surgery or had an ICD had a better expected survival than those taking drug therapy, and the negative impact of antiarrhythmic therapy was most prominent in patients with CHF class III and IV.

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.

Total Pectoral Implantation: A New Technique for Implantation of Transvenous Defibrillator Lead Systems and Implantable Cardioverter Defibrillator

We describe a new approach to tolal pectoral implantation of cardioverter defibrillators with an endocardial defibrillation lead system. Endocardial lead configuration used was an FDA approved right atrial‐superior vena cavo defibriliation spring electrode, right ventricular bipolar sensing electrode, and a pectoral patch. Endocardial leads were implanted via a cephalic or an axillary venesection. Pectoral patch was placed in a sabmuscular position. In case of failure to obtain satisfactory thresholds, a small intercostal thoracofomy was performed via fhe same skin incision and patch placed over the epicardium instead of submuscular position and used with Ihe right atrial spring electrode. The device was implanted in the pectoral region, submuscularly, over the patch. Sixteen consecutive patients underwent this approach. With a submascular patch, adequate defibrillation thresholds (< 15 joules [J]) were obtained in 14 (87.5%) patients. In the other two, defibrillation thresholds of ≤ 15) were obtained with a epicardial patch. Pectoral implantation of the device was feasible in all 16 patients and none needed repositioning. Average postimplant hospital stay was 5 days. During follow‐up period (average 5 months), none of the patients reported any major local symptoms and no problems have been encountered in device interrogation. Thus, total pectoral implantation of the cardioverter defibrillator including the patch, leads, and the device is feasible. Furthermore, in case of foilure to obtain adequate defibrillotjon thresholds with submuscular patch, an epicardial patch can easily be implanted and allows 100% successful defibrillation at energy levels of ≤ 15 J with right atrial patch configuration.

Incidence of malposition of polyvinylchloride and red rubber left-sided double-lumen tubes and clinical sequelae

Currently, fiberoptic bronchoscopy (FB) is recommended for correct positioning of double-lumen endobronchial tubes (DLTs) because of the high incidence of malpositions not appreciated by clinical signs. The aims of this study were to assess whether clinical signs allow accurate confirmation of adequate positioning with left red rubber (RR) or polyvinylchloride (PVC) double-lumen tubes and to compare the incidence of malpositions between the two tubes. Another goal was to assess whether these malpositions, not appreciated by clinical assessment, adversely affected outcome. Twenty-one adult patients scheduled for elective thoracic surgery were randomly assigned to the RR (11 patients) or PVC group (10 patients). After endobronchial intubation, the position of the tubes was adjusted until clinically satisfactory lung separation had been achieved. A single investigator performed all the FB and assessed adequacy of tube placement. Clinical and FB assessments were performed in the supine (SUP) and lateral positions. The anesthesiologists responsible for the clinical evaluation were “blinded” to the bronchoscopic findings. While in the SUP position, the tube was “too deep” to permit visualization of the carina during tracheal bronchoscopy in 5 patients (2 RR, 3 PVC). In 17 of 21 (10 RR, 7 PVC), the bronchial cuff could not be visualized, although in 1 patient (RR group), the cuff was overinflated and bulged out to partially obstruct the right main bronchus orifice. Bronchial bronchoscopy showed 4 of 11 patients in the RR group in whom the left upper lobe orifice was occluded compared with 1 only in the PVC group. The PVC did not differ from the RR in cases in which the tube was “too far out.” However, they did differ in the incidence of the tube being pushed too far in 36% in the RR versus 10% in the PVC ( p 2 , PaCO 2 , tidal volume, and the peak airway pressures in all the patients in the PVC versus the RR DLT groups show no differences between the 2 groups. In the cases of malpositioned tubes, there were no statistical differences in PaO 2 between the right and left thoracotomies during two-lung ventilation (2LV) or one-lung ventilation (OLV) (520 ± 80 v 469 ± 56 mmHg and 167 ± 105 v 325 ± 94 mmHg, respectively). In the well-positioned tubes, the comparison between right and left thoracotomies showed no statistical differences in PaO 2 , (432 ± 114 v 464 ± 71 mmHg during 2LV and 182 ± 104 v 157 ± 94 mmHg during OLV, respectively). The results of this study show that, first, there is no significant difference in ventilation between the PVC and the RR tubes as measured by PaCO 2 , peak airway pressure, and tidal volume. Second, a similar incidence of malpositions was found in both groups in the supine and lateral decubitus positions except for a higher incidence of malposition in the RR group in which the bronchial carina was not visualized during bronchial bronchoscopy. Finally, the patients with malpositioned tubes had similar arterial oxygen saturation to patients with well-positioned tubes, whether the patients were undergoing right or left thoracotomies.

Use of Single Lead VDD Pacing in Children

The development of transvenous ventricular pacing leads with proximal electrodes capable of atrial sensing and the recent availability of smaller generators has created the opportunity to treat children with complete AV block and normal sinus node function with a transvenous single lead VDD pacing system. Studies in adults have demonstrated this system to be efficacious with low complication rates. Transvenous single lead VDD pacemakers were implanted in ten children, aged 5–15 years, between December 1993 and April 1996, in our institution. The indications were complete AV block with severe bradycardia in 5 patients, second‐degree or complete A V block following congenital heart surgery in 3, complete A V block with long QT syndrome in 1, and second‐degree AV block and syncope in 1. There were no complications related to the procedure in any case. P and R wave amplitudes were measured and thresholds were determined intraoperatively on all patients. Amplitudes and thresholds were remeasured on seven patients with a mean follow‐up of 17 months; Holter monitors were performed on seven patients with a mean follow‐up of 16 months. P and H wave amplitudes were generally diminished at follow‐up compared to initial values but remained within an acceptable range for all patients. Four patients required reprogramming after pacemaker insertion, 1 received an atrial lead for dual chamber pacing, 1 required repositioning for lead dislodgment. and 1 patient required a new lead for an inadequate ventricular pacing threshold. No patient had evidence of failure to sense or capture as evaluated by Halter monitoring at last follow‐up. Single lead VDD pacing systems can be successfully used in properly selected children with high degree or complete AV block with normal sinus node function.

Subpectoral Implantation of ICD Generators: Long-Term Follow-Up

A nonthoracotomy surgical approach using an endocardial electrode and combined implantation of a subcutaneous patch and the implantable cardioverter defibrillator (ICD) generator in a Subpectoral pocket has been described. We report the long‐term follow‐up results in patients undergoing implantation using this approach. The patient population consisted of 28 patients (22 men and 6 women) with a mean age of 59 ± 12 years. The underlying heart disease consisted of coronary artery disease in 20 patients and dilated cardiomyopathy in 8 patients. Sustained ventricular tachycardia was the mode of presentation in 16 patients and sudden cardiac death in 12 patients. The mean left ventricular ejection fraction was 31%± 6%. The lead system consisted of an 8 French bipolar passive fixation rate sensing lead positioned at the right ventricular apex, an 11 French spring coil electrode positioned at the superior vena cava‐right atrial junction (surface area 700 mm2), and submuscular placement of a large patch (surface area 28 cm2) on the anterolateral chest wall near the cardiac apex via a submammary incision. A defibrillation threshold of ≤ 15 joules (J) was required for implantation. This criterion was not satisfied in five patients; thus, a limited thoracotomy was performed via the submammary incision, and the large patch was placed epicardially. The mean R wave amplitude was 12 ± 3 mV, the mean pacing threshold was 1.0 ± 0.5 V at 0.5 msec, and the mean defibrillation threshold was 12.6 ± 3 J. ICD generators implanted were the Ventak‐P in 17, PCD‐7217 in 5, and the Cadence V‐l00 in 6 patients. These patients have been followed for a mean of 14.6 ± 6 months. There was no perioperative mortality, and none of the patients developed an infection during follow‐up. Generator migration or significant discomfort requiring ICD repositioning was not observed, although one patient developed an erosion requiring surgical repair.Conclusions: Subpectoral implantation of the ICD generator is feasible and was well tolerated by all patients with an acceptable complication rate (3.5%). As the size of future generation ICDs is reduced, subpectoral implantation may become the preferred approach.