Graft vascular disease after heart transplantation.
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Coronary Disease↗
Biomedical subjects
D Hammel
Publications and source records attributed to D Hammel.
The effects of thoracic epidural anesthesia on functional recovery from myocardial stunning in propofol-anesthetized dogs.
The purpose of this investigation was to examine the effects of thoracic epidural anesthesia (TEA) on myocardial stunning during propofol anesthesia. Six dogs were chronically instrumented for measurement of left atrial, aortic, and left ventricular pressure, maximal rate of increase of left ventricular pressure, and myocardial wall-thickening fraction (WTF). Myocardial blood flow was determined with colored microspheres. Experiments were performed on separate days with 1) 10 min of left anterior descending artery (LAD) ischemia during propofol anesthesia without TEA, and 2) 10 min of LAD ischemia during propofol anesthesia with TEA. WTF was measured as baseline (BL) prior to propofol anesthesia and at predetermined time points until complete recovery from stunning. Propofol anesthesia caused a significant decrease of WTF in the LAD-perfused myocardium (LAD-WTF) compared to BL in awake animals. LAD ischemia led to a further significant decrease of LAD-WTF. There were no significant differences in LAD-WTF between the two experimental conditions at any of the time points measured. TEA did not change subendocardial blood flow in nonischemic myocardium. During ischemia neither the subendocardial/subepicardial nor the occluded/normal zone blood flow ratio were affected by TEA. After myocardial ischemia during propofol anesthesia TEA does not affect functional recovery of stunned myocardium in dogs.
Anesthesia, Epidural↗
Oxygen inhalation can differentiate gaseous from nongaseous microemboli detected by transcranial Doppler ultrasound.
BACKGROUND AND PURPOSE: Clinically silent circulating microemboli can be detected by transcranial Doppler sonography. The composition of these emboli in different clinical conditions is unclear. METHODS: We performed 1-hour transcranial Doppler sonographic recordings from the middle cerebral or posterior cerebral artery in 20 patients with mechanical prosthetic heart valves, in 78 patients with an arterial embolic source, and in 20 control subjects. During 30 minutes of this recording, the patients inspired room air and 6 L of oxygen per minute via a loosely fitting facial mask; during the remaining 30 minutes, they breathed room air only. RESULTS: There was a significant decline of embolic signals (ES) under oxygen in the patients with mechanical prosthetic cardiac valves (144 ES without oxygen versus 63 ES with oxygen; P = .002) but not in the patients with arterial embolic sources (145 ES without oxygen versus 135 ES with oxygen; P = NS). In the control subjects, no ES were found. CONCLUSIONS: ES in patients with mechanical prosthetic cardiac valves correspond mainly to gas bubbles. Oxygen inhibits the cavitation process of mechanical prosthetic heart valves or speeds up redissolution of gas bubbles generated by cavitation. In contrast, solid microemboli originating from thrombus or atheroma cannot be suppressed by oxygen inhalation. This simple method of oxygen inhalation should help to clarify the composition of microemboli in various clinical and experimental settings.
Administration, Inhalation↗
Long-term left ventricular assist device support: a novel pump rate challenge exercise protocol to monitor native left ventricular function.
A novel, hemodynamically guided exercise protocol with two different left ventricular assist device settings in two long-term recipients is presented. This protocol allows for quantitation of the contribution of the native left ventricle to total cardiac output. It facilitates estimation of the risk associated with device dysfunction, as well as prediction of left ventricular recovery and the potential for weaning.
Adult↗
Drugs or implantable cardioverter-defibrillators in patients with poor left ventricular function?
Poor left ventricular function is a predictor of sudden death. Both antiarrhythmic drugs and implantable cardioverter-defibrillators (ICDs) promise to reduce the sudden death rate in these patients and consequently improve survival. In patients without spontaneous ventricular tachyarrhythmias, only beta-blocking agents and amiodarone have been shown to reduce sudden death and improve survival in some studies, whereas class I antiarrhythmic drugs increased mortality. For patients with documented ventricular tachyarrhythmias, protection against sudden death by serially tested class I antiarrhythmic drugs is at best moderate. There is some evidence suggesting that therapy with class III antiarrhythmic drugs, either amiodarone or dl-sotalol, may reduce sudden death rates and improve overall mortality in comparison to therapy with class I antiarrhythmic drugs. ICDs have been shown to prevent sudden death reliably. In published patient cohorts in which only patients who were not inducible off antiarrhythmic drugs or still inducible on antiarrhythmic drugs received an ICD, the ICD seemed to improve overall survival in comparison to class I antiarrhythmic drugs. A small prospective randomized study that compared a conventional therapy strategy to primary ICD implantations showed an improved outcome with ICDs as therapy of first choice. However, these studies included many patients treated with class I antiarrhythmic drugs considered to be less effective. In matched control studies comparing the ICD to amiodarone or dl-sotalol, less sudden deaths and an improved overall survival could be shown for the ICD in general without stratification for left ventricular function. Thus, in patients with hemodynamically nontolerated ventricular tachyarrhythmias, the ICD seems to improve survival in comparison to class I antiarrhythmic drugs, dl-sotalol, or amiodarone. However, in patients with poor left ventricular function, therapy with ICDs seems to be less cost-effective than in patients with preserved left ventricular function. In patients with very poor left ventricular function who are evaluated for cardiac transplantation, the ICD seems to change only the mode of death from sudden to a nonsudden cardiac death if transplantation cannot be performed soon.
Anti-Arrhythmia Agents↗
Comparison of d,l-sotalol and implantable defibrillators for treatment of sustained ventricular tachycardia or fibrillation in patients with coronary artery disease.
BACKGROUND: Implantable cardioverter-defibrillators (ICDs) and d,l-sotalol are widely used to treat ventricular tachyarrhythmia and ventricular fibrillation (VT/VF). The purpose of this study was to compare the long-term efficacy of d,l-sotalol and ICDs in patients with coronary artery disease. METHODS AND RESULTS: In a case-control study, 50 patients treated with oral d,l-sotalol were matched to 50 patients treated with ICDs. Both groups were matched for sex (82 men), age (58 +/- 10 years), ejection fraction (40 +/- 12%), extent of coronary artery disease, presenting arrhythmia, and year that treatment began. In all patients in the sotalol group, VT/VF was inducible in the drug-free electrophysiological study. Induction of sustained VT/VF was suppressed by d,l-sotalol (438 +/- 95 mg/d). In the ICD group, either VT/VF was not inducible (n = 5) or inducible sustained VT/VF was refractory to antiarrhythmic drug treatment (n = 45). Sotalol treatment led to a marked reduction in arrhythmic events. Whereas 83% of the patients in the sotalol group were free of sudden death and nonfatal VT at 3 years, only 33% of the ICD patients did not receive appropriate ICD therapies (P < .005). Actuarial rates for absence of sudden death at 3 years were 85% in the sotalol group and 100% in the ICD group (P < .005). Actuarial rates for overall survival at 3 years were 75% in the sotalol group and 85% in the ICD group (P = .02). CONCLUSIONS: In this case-control study, ICD therapy was more effective tha electrophysiologically guided antiar-rhythmic treatment with d,l-sotalol in prevention of sudden death and reduction of total morality in patients with coronary artery disease. Prospective studies are needed to confirm these results.
Administration, Oral↗
Heart transplant candidates at high risk can be identified at the time of initial evaluation.
The increasing discrepancy between the numbers of patients selected for cardiac transplantation and the available donor organs requires validation of markers of high risk at the time of initial evaluation that may help to determine which patients profit from aggressive therapy. We retrospectively examined the case records of 91 heart transplant candidates selected out of a total of 140 consecutive patients referred for evaluation. Of these 91 patients, 48 were transplanted during follow-up. Of the remaining 43 patients, 25 died after a mean survival time of 1.6 +/- 2.5 months. The causes of death were pump failure in 18 (72%) and sudden cardiac death in 7 (28%). Multivariate analysis identified 4 out of 26 parameters at initial evaluation that distinguished the 25 nonsurvivors from the 18 survivors. These were: mean arterial pressure (P = 0.03), pulmonary capillary wedge pressure (P = 0.002), mean pulmonary artery pressure (P = 0.001), and fractional shortening (P = 0.007). The mode of death could not be predicted. We conclude that there are prognostic markers at initial evaluation that allow more restrictive selection of patients for cardiac transplantation and mechanical bridging.
Adult↗
Pheochromocytomas with extension into central vascular structures.
Two cases of pheochromocytomas, 1 with extension into the inferior vena cava and the second with involvement of the right atrium, are reported. Both tumors were resected in toto, 1 using inferior to superior vena cava vein-to-vein bypass and the second with the aid of hypothermic circulatory arrest. Both patients are free of recurrences or metastasis 20 and 24 month postoperatively.
Adrenal Gland Neoplasms↗
Beating heart implantation of a wearable NOVACOR left-ventricular assist device.
Implantable left-ventricular assist devices (LVAD) are successfully used as a bridge to transplant if the patient's condition is worsening and no donor organ is available. They allow recovery of compromised organ function. However, postoperative bleeding, thrombemboelism, and right-heart failure may jeopardize the important improvement of organ function and may even lead to death. We introduce our strategy for implantation of the Novacor LVAD system, which aims at minimal bleeding and maintained right-heart function. The Novacor LVAD was implanted with the heart beating during extracorporeal circulation in 8 patients, 3 of whom had previous cardiac surgery. Postoperatively, no patient developed right heart failure or had to undergo redo thoracotomy.
Adult↗
Biphasic defibrillation using a single capacitor with large capacitance: reduction of peak voltages and ICD device size.
The volume of current implantable cardioverter defibrillators (ICD) is not convenient for pectoral implantation. One way to reduce the size of the pulse generator is to find a more effective defibrillation pulse waveform generated from smaller volume capacitors. In a prospective randomized crossover study we compared the step-down defibrillation threshold (DFT) of a standard biphasic waveform (STD), delivered by two 250-microF capacitors connected in series with an 80% tilt, to an experimental biphasic waveform delivered by a single 450-microF capacitor with a 60% tilt. The experimental waveform delivered the same energy with a lower peak voltage and a longer duration (LVLD). Intraoperatively, in 25 patients receiving endocardial (n = 12) or endocardial-subcutaneous array (n = 13) defibrillation leads, the DFT was determined for both waveforms. Energy requirements did not differ at DFT for the STD and LVLD waveforms with the low impedance (32 +/- 4 omega) endocardial-subcutaneous array defibrillation lead system (6.4 +/- 4.4 J and 5.9 +/- 4.2 J, respectively) or increased slightly (P = 0.06) with the higher impedance (42 +/- 4 omega) endocardial lead system (10.4 +/- 4.6 J and 12.7 +/- 5.7 J, respectively). However, the voltage needed at DFT was one-third lower with the LVLD waveform than with the STD waveform for both lead systems (256 +/- 85 V vs 154 +/- 51 V and 348 +/- 76 V vs 232 +/- 54 V, respectively). Thus, a single capacitor with a large capacitance can generate a defibrillation pulse with a substantial lower peak voltage requirement without significantly increasing the energy requirements. The volume reduction in using a single capacitor can decrease ICD device size.
Adult↗
Improved sensing signals after endocardial defibrillation with a redesigned integrated sense pace defibrillation lead.
Adequate sensing is a basic requirement for appropriate therapy with ICDs. Integrated sense pace defibrillation leads, which facilitate ICD implantation, show a close proximity of sensing and defibrillation electrodes that might affect the sensing signal amplitude by the high currents of internal defibrillation. In 99 patients, we retrospectively examined two integrated sense pace defibrillation leads, either both with a distance of 6 mm between the tip of the lead (sensing cathode) and the right ventricular defibrillation electrode (sensing anode) or one with a distance of 12 mm. Three seconds after a shock of 20 J, mean sensing signal amplitude during sinus rhythm (SR) decreased from 10.5 +/- 4.3 mV to 5.1 +/- 3.7 mV (P < 0.001) for the 6-mm lead, but showed no significant decrease for the 12-mm lead. The degree of signal reduction was inversely related to the time passed since defibrillation. Significant differences in reduction of sensing signal amplitude concerning monophasic and biphasic shocks could not be observed. Mean sensing signal amplitude of VF after shocks that failed to terminate it decreased in the same order as during SR (from 8.3 +/- 4.1 mV to 4.1 +/- 3.2 mV), but resulted in no failure of redetection during ongoing VF. DFTs did not differ for the 6-mm and the 12-mm lead. In conclusion, close proximity of the right ventricular defibrillation coil to the sensing tip of an integrated sense pace defibrillation lead causes energy and time related reduction in sensing signal amplitude after defibrillation, and might cause undersensing in the postshock period. A new lead design with a more proximal position of the right ventricular defibrillation coil avoids these problems without impairing DFTs.
Defibrillators, Implantable↗
[Inadequate therapies with implantable cardioverter-defibrillators--incidence, etiology, predictive factors and preventive strategies].
Patients with implantable cardioverter defibrillators (ICD) often suffer inappropriate ICD-therapies. The incidence, causes and risk factors of ICD-therapies for a rhythm other than ventricular tachyarrhythmias (VT) were determined retrospectively in 462 consecutive patients (pts). Inappropriate ICD-therapies were identified based on stored R-R intervals and/or electrograms. Eighty-two pts (18%) had inappropriate ICD-therapies. Actuarial rates for inappropriate ICD-therapies were 13%, 20%, 24% and 29% at 1, 2, 3 and 4 years after ICD-implantation, respectively. Atrial fibrillation with rapid ventricular response was the most common cause (34 pts, 39%). In 26 pts (30%), sinus tachycardia triggered inappropriate ICD-therapies, in 21 pts (24%) overseeing, mostly due to fractures and insulation failures of the leads, in three pts atrial flutter, in two pts non-sustained VT, in one pt supra-ventricular tachycardia and in another pt T-wave double sensing caused inappropriate ICD-therapies. In order to prevent recurrences of inappropriate ICD-therapies due to atrial fibrillation or sinus tachycardia, a rate stability (n = 19) or onset (n = 15) criterion was programmed, 41 pts additionally received beta-blocking agents and/or digoxin. In pts with overseeing an operative revision of lead system was performed. During further follow-up (15 +/- 13 months), 15 pts had recurrences of inappropriate ICD-therapies (eight pts due to atrial fibrillation, three due to sinus tachycardia and four due to overseeing). On multivariate analysis (Cox regression), history of atrial fibrillation, maximum heart rate during exercise and low cut-off rate for VT-detection were predictors of inappropriate ICD-therapies. Thus, inappropriate ICD-therapies are frequent, especially in the first year after implantation. Additional detection criteria, beta-blocking agents and/or digoxin prevent recurrences in most patients. In patients with a history of atrial fibrillation, high heart rate during exercise or a low cut-off rate for VT-detection, activation of additional detection criteria should be considered directly after ICD-implantation.
Adult↗
Bipolar transvenous defibrillation: efficacy of two different positions of the anode.
For most nonthoracotomy defibrillation lead systems, the transvenous anode can positioned independently of the right ventricular (RV) cathode. Usually a vertical position in the superior vena cava (SVC) is chosen. However, it is unknown if this position yields the optimal defibrillation threshold (DFT). Therefore, in 15 patients undergoing defibrillator implantation the SVC position was compared in a crossover study design with a horizontal position in the left brachiocephalic vein (BCV). Mean DFT was not different for SVC and BCV (19.2 +/- 9.6 J vs 18.5 +/- 9.1 J) but DFT of individual patients differed by up to 12 joules. A positive correlation between impedance and DFT in the BCV position (r = 0.6; P < or = 0.05) indicated that the improved geometry of the defibrillation field with the BCV position is opposed by a higher impedance found for this position (63 +/- 15 omega vs 52 +/- 7 omega). Thus, defibrillation is not improved in general although individual patients might benefit.
Aged↗
Internal defibrillation with smaller capacitors: a prospective randomized cross-over comparison of defibrillation efficacy obtained with 90-microF and 125-microF capacitors in humans.
INTRODUCTION: The size of current implantable cardioverter defibrillators (ICD) is still large in comparison to pacemakers and thus not convenient for pectoral implantation. One way to reduce ICD size is to defibrillate with smaller capacitors. A trade-off exists, however, since smaller capacitors may generate a lower maximum energy output. METHODS AND RESULTS: In a prospective randomized cross-over study, the step-down defibrillation threshold (DFT) of an experimental 90-microF biphasic waveform was compared to a standard 125-microF biphasic waveform. The 90-microF capacitor delivered the same energy faster and with a higher peak voltage but provided only a maximum energy output of 20 instead of 34 J. DFTs were determined intraoperatively in 30 patients randomized to receive either an endocardial (n = 15) or an endocardial-subcutaneous array (n = 15) defibrillation lead system. Independent of the lead system used, energy requirements did not differ at DFT for the experimental and the standard waveforms (10.3 +/- 4.1 and 9.5 +/- 4.9 J, respectively), but peak voltages were higher for the experimental waveform than for the standard waveform (411 +/- 80 and 325 +/- 81 V, respectively). For the experimental waveform the DFT w as 10 J or less using an endocardial lead-alone system in 10 (67%) of 15 patients and in 12 (80%) of 15 patients using an endocardial-subcutaneous array lead system. CONCLUSIONS: A shorter duration waveform delivered by smaller capacitors does not increase defibrillation energy requirements and might reduce device size. However, the smaller capacitance reduces the maximum energy output. If a 10-J safety margin between DFT and maximum energy output of the ICD is required, only a subgroup of patients will benefit from 90-microF ICDs with DFTs feasible using current defibrillation lead systems.
Adolescent↗
Benefits of treatment with implantable cardioverter-defibrillators in patients with stable ventricular tachycardia without cardiac arrest.
BACKGROUND: The availability of implantable cardioverter-defibrillators (ICD) that are capable of antitachycardia pacing may lead to an increased use of ICDs in patients with haemodynamically tolerated ventricular tachycardia without a history of cardiac arrest. The frequency of potentially life-threatening fast ventricular tachycardias (cycle length < 250 ms) was investigated in patients who had a third generation ICD with endocardial leads implanted because they had haemodynamically tolerated ventricular tachycardia without a history of cardiac arrest. METHODS: Between January 1990 and October 1993, 50 patients (age (mean (SD)) 60 (11); ejection fraction 39 (16)%; 82% with coronary artery disease and 8% with dilated cardiomyopathy) with haemodynamically tolerated ventricular tachycardia (cycle length (mean (SD)) 348 (60) ms; range 250-500 ms) and without a history of cardiac arrest were treated with third generation ICDs that were capable of antitachycardia pacing. Fast ventricular tachycardia had been induced in 14 (28%) during baseline electrophysiological study. The benefit of ICD treatment was estimated as the difference between total mortality and the occurrence of fast ventricular tachycardia that would have been fatal if it had not been terminated. RESULTS: During follow up of 17 (12) months, 33 patients (66%) had a total of 3861 episodes of ventricular tachycardia. 91% of these episodes were terminated by antitachycardia pacing. 11 patients (22%) had episodes of potentially life-threatening fast ventricular tachycardia and 3 of these also had inducible fast ventricular tachycardia. One patient died suddenly 27 months after implantation. The difference between survival without fast ventricular tachycardia and total mortality was 9%, 12%, 27%, and 27% at 6, 12, 18, and 24 months, respectively. CONCLUSIONS: About a fifth of patients who had been given an ICD to treat haemodynamically tolerated ventricular tachycardia and who had no history of cardiac arrest experienced fast ventricular tachycardia during follow up requiring immediate cardioversion. Prospective studies are needed to investigate whether the prognosis of patients with a history of haemodynamically tolerated ventricular tachycardia without cardiac arrest is improved by ICD therapy.
Cardiomyopathy, Dilated↗
Implantable cardioverter defibrillator therapy in patients with arrhythmogenic right ventricular cardiomyopathy, long QT syndrome, or no structural heart disease.
Recent technical developments in implantable cardioverter defibrillator (ICD) systems and reduced operative mortality and morbidity rates associated with ICD implantation have expanded the indications for ICD treatment of ventricular tachyarrhythmias. This review summarizes data regarding ICD therapy in patients with arrhythmogenic right ventricular cardiomyopathy, long QT syndrome, and idiopathic ventricular fibrillation and presents preliminary concepts for identification of patients who will benefit more from ICD therapy than from pharmacologic and other nonpharmacologic approaches. Recent studies suggest that ICD therapy may improve long-term prognosis by reliably terminating recurrences of life-threatening arrhythmias. Appropriate ICD therapies during mean follow-up periods of 12 to 36 months occurred in 30% of patients with idiopathic ventricular fibrillation to 50% of patients with arrhythmogenic right ventricular cardiomyopathy and long QT syndrome. At present no strict recommendations can be given for ICD implantation in these patients. However, at least in cardiac arrest survivors in whom the clinical arrhythmia is not reproducibly inducible during electrophysiologic study, ICD therapy appears to be superior to other treatment options with regard to long-term survival and thus should be considered as a first-line treatment. We are hopeful that continued study of long-term follow-up with and without ICD treatment and improved risk stratification will lead to better criteria for selection of treatment options.
Adult↗
Single-incision implantation of cardioverter defibrillators using nonthoracotomy lead systems.
This study describes the placement of a newly designed implantable cardioverter defibrillator in a subpectoral device pocket using the incision for venous access in 16 patients undergoing implantation of an implantable cardioverter defibrillator with a nonthoracotomy lead system. The endocardial lead system consisted of a right atrial/superior vena cava defibrillation spring electrode and a right ventricular bipolar sensing/defibrillation electrode, inserted by cephalic venotomy or by puncturing of the subclavian vein. As a result of intraoperative testing using biphasic shocks the defibrillation threshold (DFT) had to be less than 24 J, otherwise an additional subcutaneous patch electrode was placed in the lateral chest wall near the cardiac apex through another incision. All patients received a nonthoracotomy lead system in combination with a subpectoral device placement. In 11 of 16 patients the endocardial leads alone were sufficient (DFT, 13.4 +/- 7.0 J), 5 of 16 patients (31%) required an additional subcutaneous patch electrode to achieve proper device function (DFT, 14.6 +/- 9.0 J). The operation lasted 93 +/- 20 minutes. This was a significant (p < 0.05) lower time consumption than standard nonthoracotomy approach combined with abdominal device placement (120 +/- 50 minutes). There were no postoperative complications. During follow-up period (average, 4 months), none of the patients reported major local symptoms, especially no device migration occurred. This approach, in contrast to an abdominal device placement, avoids another incision and subcutaneous tunneling of leads. In 11 of 16 patients defibrillator implantation by a single incision in the deltoideopectoral groove was possible.
Aged↗
Nonthoracotomy defibrillator implantation: a single-center experience with 200 patients.
Nonthoracotomy leads for defibrillator implantation and biphasic shocking devices are under investigation. Implantation success and mortality and morbidity of the procedure determine the operative course. Lead-associated complications, late infection, and freedom of sudden cardiac death characterize the follow-up period with respect to the implanted device. From October 1989 to March 1993 in 200 patients, 205 (including five infections caused by reimplantations) transvenous or transvenous-subcutaneous lead systems were tested. Mean ejection fraction was 0.40 +/- 0.16. In 62.5% (125/200) coronary artery disease and in 19% (38/200) cardiomyopathy was the underlying disease (59 patients with prior cardiac operations). Leads were implanted with defibrillation thresholds less than 25 J in 195 patients, whereas 10 patients received intrathoracal patches. Since biphasic shocks became available, no nonthoracotomy lead system has failed in the last 115 consecutive patients. Perioperative mortality in the nonthoracotomy group was 1% (2/195). In 6.2% (12/193) of the surviving patients, perioperative complications occurred. Major problems were bleeding from the device or patch pocket (n = 6) and early infection (n = 2). During the follow-up of 20 +/- 10 months, lead-associated complications (dislocation, lead fracture, insulation defect, loss of sensing) occurred in 9 patients and in 5 patients late infection appeared. Within the follow-up period no patient died suddenly, and 134 patients received therapeutic interventions by the device. Defibrillator implantation using nonthoracotomy leads, especially combined with biphasic shocking devices, is applicable in almost every patient. During the operative course and follow-up, the defibrillator-associated morbidity and mortality is at the same level as or lower than when using patch lead systems.
Adolescent↗