Biomedical subjects

R Moosdorf

Publications and source records attributed to R Moosdorf.

At least 37 records · Page 2Linked to original sources

PubMed1998

[Postoperative imaging of synthetic coronary artery bypass graft patency by means of CT angiography].

PURPOSE: CT angiography was performed in 12 patients with insufficient autologous graft situations to evaluate postoperative patency and situation of the proximal, distal and coronary artery anastomoses of synthetic Perma-Flow coronary artery bypass grafts. METHODS: Bypass grafts were evaluated postoperatively with spiral CT of the mediastinum. At a flow rate of 3 ml/s, 120 ml of contrast material were applied over a cubital vein. Slice thickness was 3 mm, maximum pitch factor 2 and image reconstruction was performed at 2 mm increment. Shaded surface displays were analysed together with axial scans for bypass evaluation. RESULTS: 8 out of 12 synthetic bypasses proved to be patent. One bypass was completely occluded and in three patients the distal portions of the grafts were occluded. Coronary angiography performed in one case confirmed complete bypass occlusion. Due to the occlusions, 8 distal and 12 proximal anastomoses were visible. Only 8 out of 19 side-to-side coronary artery anastomoses could be sufficiently well imaged with this technique. CONCLUSIONS: CT angiography is suitable for postoperative screening of synthetic coronary bypasses to determine the patency and anastomotic situations. Coronary artery anastomoses however are not sufficiently imaged and coronary angiography continues to be required.

Adult↗

PubMed1998

[Animal experiment study of the design of microelectrodes for selective detection of epicardial potassium ion activities].

Early detection of myocardial ischaemia following cardiac surgery remains a central problem of intensive care medicine. On the basis of the observation in the epicardium that an elevated potassium activity accompanies myocardial ischaemia, a miniaturized electrode system for the measurement of epicardial potassium concentration was constructed and tested. Different types of electrode were implanted in two groups of rabbits. The electrode parameters were satisfactory (slope, screening) and it proved possible to record interference-free myocardial ion potentials, which with regard to the ionophores used is selective for potassium ion activity in the solid phase electrode. The system thus meets the prerequisites for further investigations into its suitability for early diagnosis of ischaemia.

Animals↗

PubMed1998

[Hemodynamic-kinetic controlled extracorporeal circulation in heart surgery].

Mimicking the physiological characteristics of the circulatory system, pulsatile bloodflow has also been introduced into extracorporeal perfusion to avoid known postoperative complications. In a mathematical consideration of the situation bloodflow is seen as a function of time F(t) for approximately constant vessel diameter over a given time. The kinetic energy of a column of blood produced by the heart-lung machine is transmitted directly to the arterial circulation via the aorta. The nature of the energy release can give rise to both positive (organ perfusion) and negative (damage to endothelium) effects. This study investigates how this energy release can be optimised, using the following experimental approach. A Doppler flow-measuring probe is placed on the ascending aorta to monitor the extracorporeal circulation. At the same time, the blood pressure is measured and converted to a pressure-flow curve via an A/D converter. On the basis of the parameters thus obtained, the energy released by the heart-lung machine is calculated. By regulating the functional parameters of a new generation of heart-lung machines, the bloodflow can then be adapted to the physiological requirements. Within the pulse period (cycle) a 20% rise phase ending in a slightly increasing plateau is established. The energy increase within a cycle should not exceed 150 joules. To optimize the mode of functioning of the heart-lung machine, we introduced the "energy-equivalent pressure" (EEP). Adaptation of the EEP to the physiological conditions required a basic flow of 60% at a pulse rate of 60/min and a pulse duration of 35% within the pulsatile flow interval.

Adult↗

PubMed1997

Patients' profiles in end stage coronary artery disease. Indications for treatment with transmyocardial laser revascularisation.

There is a subgroup of patients with coronary artery disease who are refractory to the therapeutical methods so far applied. We report on 128 patients who fulfill this definition and have therefore undergone pure transmyocardial laser revascularisation (TMLR) or transmyocardial laser revascularisation in combination with coronary bypass surgery at our institution. The patients can be characterized by a long history of coronary artery disease with multiple revascularizing procedures, e.g. bypass surgery or percutaneous transluminal coronary angioplasty (PTCA), pronounced symptoms of coronary artery disease and chronic heart failure in the presence of markedly reduced left ventricular ejection fractions and intense antiischemic medical therapy. The patients were 62.2 +/- 9.8 (SD) years of age, in 89.9% of them at least one bypass operation and in 44.5% up to more than three percutaneous transluminal coronary angioplasties (PTCAs) had been performed prior to TMLR. There was a history of myocardial infarction in 90.7% of patients and 89.8% were in the Canadian Cardiovascular Society (CCS) classes III or IV and 94.5% of them were in the NYHA classes III or IV. The left ventricular ejection fraction was 49.5 +/- 16.4% and all of the patients were under intense antiischemic medical treatment which included nitrates or molsidomine in 96.9%, beta blockers in 53.1%, angiotensin converting enzyme inhibitors (ACE inhibitors) in 44.5%, digitalis in 22.7% and diuretics in 52.3% of patients. The preoperative data on myocardial viability, inducible ischemia and coronary morphology provided important clinical information for the decision, which revascularizing method would be the most appropriate for each vessel or myocardial region. This had to be weighed against the patient's operative risk, which is predominantly determined by the left ventricular ejection fraction, the arteriosclerotic involvement of the remaining vascular system and concomitant diseases, particularly of pulmonary origin.

Aged↗

PubMed1997

[Transmyocardial laser revascularization in stable and unstable angina pectoris].

Endstage coronary artery disease still remains a therapeutic challenge. An increasing number of patients is no longer amenable for direct revascularization by PTCA or coronary bypass surgery and does also no longer respond to maximum medical therapy. This fact has directed the interest again towards surgical techniques of indirect revascularization, which had been introduced by Beck and other surgeons more than 60 years ago. Among these attempts we can also find transmyocardial needle punctures, firstly performed by Sen in Bombay. In the early eighties it was Mirhoseini, who used a laser for creating these transmural channels, primarily in combination with coronary bypass surgery at the arrested heart and later on together with Crew as a sole therapy at the beating heart. The idea behind this transmyocardial laser revascularization (TMLR) was a "reptilization" of the human heart, which meant a direct blood supply from the ventricle into the ischemic myocardium. Whereas this theory has not proven to be true, as the surface area of these channels is not sufficient for the nutrition of the surrounding myocardial tissue by diffusion or convection, different models have been developed by anatomical, experimental and clinical studies, such as the connection between the laser channels and intramyocardial vessels or capillaries, analogous to ventriculo-coronary connections in human anatomy or pathology as for example those connections described in children with pulmonary atresia and intact ventricular septum or the Thebesian veins. Moreover the laser trauma may also simply contribute to the induction of neoangiogenesis. While the function of TMLR is still not clearly defined, clinical studies in the United States and also in other countries have proven the clinical efficacy in a cohort of severely diseased patients undergoing this procedure. Accordingly more than 2/3 of all patients after TMLR showed a significant improvement of more than 2 angina classes (CCS) as well as a decrease in medication and hospitalization. Moreover there was also a reduction of ischemic areas demonstrated by szintigraphy and, in one study from Houston, also by positron emission tomography. While the overall mortality in all those studies is still considerably high, a reduction could be achieved by a stricter selection of patients excluding especially those with a severely impaired left ventricular function. As demonstrated by preliminary data from the last phase III FDA-study, TMLR may even reduce long-term mortality compared to maximum medical therapy in a randomized group of patients. Our own experiences in 134 patients also confirmed a significant reduction of angina after TMLR alone (n = 67) or in combination with bypass surgery (n = 67) with the majority of patients being in angina class 1 and 2 (CCS) 6 months after surgery. All of these patients were in angina class 3 and 4 before surgery. Nuclear scans could demonstrate an improved perfusion in more than 40%. Further studies as well as other clinical and also experimental investigations have still to be awaited, before the definitive role of TMLR within the armamentarium against coronary artery disease can be determined. However, it is already a therapeutic option for those highly symptomatic patients, who cannot be offered a different treatment modality.

Adult↗

PubMed1997

[Transmyocardial laser revascularization and rehabilitation].

Transmyocardial laser revascularization (TMLR) is a new technique for patients with CAD or heart attack to revascularize ischemic areas of the myocardium in which the localisation or the condition of the vessels does not allow bypass grafting. This study shows the results in observation of patients before and during the first 3 months after TMLR. Of 110 patients operated on from 1994 to 1996, 86 were evaluated for well being (quality of life), using NYHA- and CCS-classification, stress test and nitril-scintigraphy at rest and under stress conditions. 51 patients, of whom 11 were females, underwent TMLR combined with coronary artery bypass graft (CABG). 35 male patients were treated singularly with TMLR. The average age in both groups was 59 years (+/- 23). All patients were subject to phase I rehabilitation in specialised institutions after being mobilised in the operating hospital. The evaluations took place on the day of admission to the hospital prior to surgery, within 10 days after surgery and 3 months following. The average stay in the rehabilitation-institution was between 4 and 6 weeks. Our findings demonstrate that both groups profited from the procedures, while the TMLR/CABG group showed a faster recovery and a better outcome. In comparison to 57% of the TMLR group, 85% of the patients in the TMLR/CABG group reported an improvement ranging from good to significant in quality of life assessments. The TMLR/CABG rated from an average of initially 3.4 (+/- 0.6) to 2.1 (+/- 0.8) after 3 months at NYHA- and 3.3 (+/- 0.7) to 1.7 (+/- 0.8) at CCS-classification. The TMLR group rated from 3.6 (+/- 0.5) to 2.4 (+/- 0.8) in NHYA- and from 3.4 (+/- 0.5) to 1.9 (+/- 0.7) on the CSS-scales. A remarkable improvement was noted in the stress test with an increase in power and endurance from 21 to 89 watts for the combined group and 8 to 81 watts for the TMLR treated patients, who generally recovered more slowly. The perfusion scan showed the same tendencies as previously reported but in some cases the results were not congruent with other findings. Overall, our findings indicate that there is a benefit for terminally symptomatic CAD patients after TMLR, but an observation period of 3 months does not allow for final conclusions on this matter. Rehabilitation seems to be of value for TMLR-patients since they have shown a markedly better performance following 3-month treatment, but further data from clinical randomised trials are needed to determine the influence of TMLR with short- and long-term rehabilitation on the prognosis of the disease.

Adult↗

PubMed1997

[Transmyocardial laser revascularization--morphologic, pathophysiologic and historical principles of indirect revascularization of the heart muscle].

Under normal conditions the coronary system of the human heart is not hermetically isolated from the surrounding structures nor the ventricles, but is in various ways connected to the adjacent arteries and the cardiac chambers. These natural connections have been models for most surgical efforts to revascularize the myocardium. Numerous anastomoses between the aorta and the coronary branches functionally resemble aorto-coronary bypass grafts. Coronaro-ventricular anastomoses do also exist in the myocardium and therefore transmyocardial laser revascularization should allow blood to penetrate from the ventricle into the myocardium. This process should not be called "reptilization" of the human heart, as in large reptilian hearts the nutrition of an extensive amount of myocardium only by diffusion is highly unlikely. Transmyocardial laser revascularization results in a relevant reduction of clinical symptoms and an increase of exercise capacity in approximately two thirds of the patients treated. Objective data of enhanced myocardial perfusion as assessed by positron emission tomography and stress echocardiography has up to now only been presented by smaller studies. Open laser channels are rarely visualized by conventional ventriculography for the limited resolution of the technique. Possibly contrast-echocardiography may offer a more appropriate option to proof the systolic filling of the laser channels, as recently reported in patients. This would allow a correlation between clinically successful revascularization and functioning channels in contrast to an early or late failure due to the closure of the channels. As to the current opinion, transmyocardial laser revascularization is no alternative to established medical, interventional or surgical therapies but may in conjunction with bypass surgery or as a sole procedure offer a new option for those patients, who were recently considered to be refractory to conventional treatment. Experimental studies in particular should contribute to the understanding of therapeutic mechanisms and lead to standardized indications in the surgical treatment of end-stage coronary heart disease. Even though in transmyocardial laser revascularization the perioperative risk depends mainly on the degree of cardiac disease and the overall state of the patient, and impaired left ventricular function is per se no exclusion criterium, if viable myocardium is detectable. Many questions concerning indications, long-term prognosis and pathophysiological mechanisms are still open to discussion and have to be answered in order to find standardized applications for treatment of end-stage coronary artery disease.

Animals↗

PubMed1997

Papillary muscle injury after blunt chest trauma.

In many cases blunt chest trauma involves cardiac lesions, such as pericardial effusion, aneurysma dissecans, or valvular rupture. Early diagnosis with routine transthoracic and/or transesophageal echocardiography is essential to prevent a fatal outcome. In the case reported, a previously healthy 68-year-old woman fell 7 meters from the roof of a barn and sustained blunt injury to the chest as well as fractures of the face. Physical examination revealed a systolic murmur at the cardiac apex, and chest x-ray film showed a severe pulmonary edema. Transesophageal echocardiography demonstrated a ruptured anterolateral papillary muscle with fourth degree mitral insufficiency. An immediate mitral valve replacement was necessary.

Accidental Falls↗

PubMed1997

[Transmyocardial revascularization].

Transmyocardial laser revascularization refers to the perfusion of the reptilian heart with its large ventriculo-myocardial channels and to well-known ventriculo-coronary connections in congenital heart defects. By a high energy CO2-laser transmural channels can be created at a beating heart and may, by connecting to the intramyocardial capillary network or by inducing a neocapillarization, improve the blood supply to the ischemic myocardium. This indirect method of revascularization is indicated in symptomatic patients with diffuse coronary heart disease, not accessible by conventional methods like PTCA or coronary bypass surgery. Worldwide, this new kind of operation has already been performed in some 100 intractable patients. In our hospital 79 patients have been treated with this new technique, 37 of them in conjunction with conventional bypass surgery. The majority of those patients had already undergone one or two bypass operations. The perioperative mortality was 11.4% including three non cardiac events. Postoperative follow-up after 3 and 6 months showed among the reinvestigated patients a significant improvement concerning angina- (CCS) and clinical classification (NYHA). Scintigraphy after the same time period revealed an improvement of myocardial perfusion in 50% of the reinvestigated patients. These results as well as the international reports demonstrate a clinical efficacy of this new therapeutic approach in a selected group of severely diseased patients. Further objective data and also experimental studies have to confirm the role of this new method in the treatment of diffuse coronary heart disease.

Angina Pectoris↗

PubMed1996

Epicardial neodymium. YAG laser photocoagulation of ventricular tachycardia without ventriculotomy in patients after myocardial infarction.

BACKGROUND: Surgical ablation of ventricular tachycardia (VT) after myocardial infarction has been reported by different endocardial approaches. The ventriculotomy may increase mortality of the procedure. METHODS AND RESULTS: We report on nine patients who suffered from recurrent VT in the late post-myocardial infarction period. Significant stenoses were detected in all patients. The mean left ventricular ejection fraction was 43.1 +/- 8.3%. Left ventricular scar (n = 9) was seen. The mean NYHA class was 2.2 +/- 0.4. Sustained VT (mean cycle length, 293 +/- 52 ms) occurred spontaneously (n = 9) and could be induced reproducibly. Catheter mapping detected a prematurity of -42 +/- 13 ms in six patients. Clinical VT was inducible during surgery in seven patients. Middiastolic potentials were detected from the epicardial surface (n = 3), and premature potentials were found (n = 8 with prematurity of -108 +/- 46 ms). Application of neodymium/yttrium/argon/ garnet (Nd:YAG) laser energy to early epicardial activation terminated the arrhythmia (n = 7). Ventriculotomy was not performed. Seven patients have been free of VT for a mean follow-up period of 17 +/- 11 months; one patient relapsed and was treated with an implantable cardioverter-defibrillator, as was a second patient with inducible VT after surgery. CONCLUSIONS: Surgical Nd:YAG laser photocoagulation of VT on the epicardial surface of the heart in post-myocardial infarction patients without ventriculotomy is safe and has a high success rate. At the present time, this method is recommended in patients with sustained and tolerated VT who need bypass surgery. This is the first report on epicardial laser ablation of VT in post-myocardial infarction VT.

Adult↗

PubMed1996

[Blunt thoracic trauma with aortic rupture and lung contusion caused by hoof kick in a 15-year-old girl. Diagnostic and therapeutic management].

The number of published cases of adolescents surviving thoracic aortic injuries with accompanying severe thoracic injuries is small. Only 20-30% of all these patients reach the trauma center alive. In the present case we demonstrate the diagnostic, operative and intensive care management in a 15-year-old girl. The exact interpretation of the AP thoracic X-ray in connection with a typical mechanism of injury led to the detection of a haemomediastinum. This is very important in the further development of diagnostics, because the conventional X-ray picture does not show significant signs in the case of an incomplete aortic rupture. Diagnostic hints have to be derived from the detection of the haemomediastinum. The girl was operated on under left heart bypass. Spinal ischaemia was absent after surgery, and renal failure also did not occur. The adjacent severe lung confusion healed under kinetic therapy with a kinetic treatment table without pulmonary complications.

Adolescent↗

PubMed1996

[Indications for transmyocardial laser therapy].

In symptomatic endstage coronary artery disease after full medical therapy (antianginal drugs, betablockers and ACE-inhibitors) further therapeutical options both for the interventional cardiologist with little hope for improvement by PTCA, stent, rotablation and atherectomy and for the cardiac surgeon with bypass surgery and endarterectomy are not available by definition due to the diffuse arteriosclerotic vessel morphology. In those patients one can therefore consider transmyocardial laser therapy (TMR) as the ultimate treatment option. It then is primarily a palliative measure to reduce the patient's symptoms. Improving perfusion and prognosis remains the most important goals, however. TMR can be utilized as the only revascularizing treatment measure or in combination with CABG or PTCA. According to data from international registries, few controlled and several non controlled studies and our own registry in Marburg with now 101 patients improvement of angina and/or dyspnoea can be expected in more than 60% of patients with end stage coronary artery disease (CAD). The patient cohort comprises symptomatic individuals after CABG or multiple PTCAs or with diffuse CAD in diabetes mellitus or with most severe hypercholesterinemia. We consider these above mentioned criteria as the only validated criteria to enter patients with endstage CAD in our controlled study. Hypothetical options for treatment by TMR such as vasculopathies after heart transplantation, cardiomyopathies under the notion of a possible but not proven microangiopathy are not accepted in our institution at present. Before TMR all patients are assessed for their angina class according to the Canadian Cardiac Society (CCS I-IV)) and their exercise capacity according to the New York Heart Association classification (NYHA I-IV) and reassessed regularly after 3, 6 and 12 months. Thallium/Te MIBI scans at rest- and whenever possible at exercise as well as stress echocardiography are carried in the patients to assess symptomatic improvement, alterations in myocardial perfusion and functional efficacy by TMR. By intermediate analysis the 101 patients of our registry more than 60% of the patients had improved their angina class by at least one classe, some patients have improved perfusion as assessed by scintigraphy, which makes at present a trend but not yet a significant difference, whereas central hemodynamics and ejection fraction remained virtually unchanged in most patients reassessed after TMR. In our analysis mortality of the 101 TMR patients was assessed and plotted on Kaplan Meier survival curves. Mortality at 6 months was 11%. When compared to a historical group of patients with identical CCS and comparable NYHA classes, who were worked up in the manner of a case control study, the TMR mortality was marginally but not yet significantly lower than one would expect from these control patients with terminal CAD treated purely by medication: Their 6 months mortality was 14%. Remarkably but not unexpectedly patients with comparable CCS classes, who could still be treated by PTCA and/or CABG had a significantly lower 6 months mortality than TMR patients or patients on antianginal drugs only. The pathophysiological mechanisms for the symptomatic improvement by laser therapy are not yet fully understood. The 1 mm transmyocardial channels created by the CO2 laser have been postulated to permit perfusion from the ventricular cavity and to seek connection to capillaries and vessels present in the malperfused myocardium thus improving the perfusion by newly created connections and sinusoids from the ventricular cavity. Although there is clear evidence for the presence of open channels acutely and within a few days after TMR therapy little evidence in man is as yet available on the question whether the channels remain open in the long run and, if so, whether they can actually improve perfusion to a substantial degree...

Angioplasty, Balloon, Coronary↗

PubMed1996

[Transmyocardial laser revascularization--limits and possibilities].

Indications for interventional catheter techniques and bypass surgery have been extended to more complex lesions and also the number of reoperations after primary successful interventions has increased due to progression of the underlying disease. Finally a number of patients remains still symptomatic but, as a consequence of a very diffuse distribution of atherosclerotic lesions, is no longer accessible with conventional techniques of direct revascularization. This has drawn the attention again to indirect techniques of myocardial revascularization. Transmyocardial laserrevascularization offers a new option in reperfusing the ischemic myocardium via transmural channels from the ventricular cavity. As to the function of the channels, it is not quiet clear, wether they may connect to intramyocardial capillaries or may themselves induce a neoangiogenesis. However the clinical follow up in patients with intractable angina pectoris shows a significant improvement. At our hospital a number of 117 patients have been treated with this new method, 53 of them in conjunction with conventional bypass surgery. Clinical follow up after three and six months postoperatively showed a significant improvement concerning angina (CCS) and exercise tolerance (NYHA). This could also objectively be demonstrated by scintigraphy with an increased myocardial perfusion in 50% of the reinvestigated patients. Ischemic areas can still be seen, but occur at a significantly higher exercise level, demonstrating an improved but not normalized myocardial blood supply. The transmyocardial laserrevascularization is no alternative to well established procedures like PTCA or bypass surgery, but can be seen as a therapeutic option for those symptomatic patients recently being intractable. Further longterm studies and also experimental investigations have to evaluate the definitive role of this new treatment for endstage coronary heart disease.

Adult↗

PubMed1995

Incidence of ICD lead related complications during long-term follow-up: comparison of epicardial and endocardial electrode systems.

UNLABELLED: The aim of this study was to evaluate the long-term stability of epicardial and endocardial lead systems for third-generation cardioverter defibrillators (ICDs) and to assess the usefulness of diagnostic tools. One hundred forty patients with 61 epicardial (43.6%) and 79 nonthoracotomy systems (56.4%) were followed for 25 +/- 19 months. A total of 18 (12.9%) lead related complications were documented. Complications of epicardial systems were detected in 10 patients (16.4%) during a follow-up time of 36 +/- 8 months: crinkling of patch electrodes in 6 patients (9.8%), insulation breakage of sensing electrodes in 2 patients (3.3%), and adapter defect in 2 patients (3.3%). Eight of the patients (10.1%) with transvenous-subcutaneous systems had lead related complications during a 13 +/- 6 months follow-up: fracture of the subcutaneous patch lead in 2 patients (2.5%), dislodgement of the right ventricular lead in 2 patients (2.5%), dislodgement of the superior vena cava lead in 2 patients (2.5%), insulation breakage of sensing electrodes in 1 patient (1.3%), and connector defect in 1 patient (1.3%). There was no significant difference in the incidence of lead related complications between epicardial and endocardial systems (P > 0.05). Fractures, dislodgements, and crinklings were documented within the first 8 +/- 5 months by regular chest X ray. Defects of insulation, adapter, or connector were detected 22 +/- 10 months after implantation and were associated with delivery of multiple inappropriate ICD therapies. An operative lead revision was indicated for 4 epicardial (6.6%) and 6 endocardial (7.6%) lead systems. CONCLUSIONS: Endocardial lead systems offer a similar long-term stability as compared to epicardial lead systems. Chest X ray is the most useful tool to detect lead fracture, dislodgment, and patch crinkling. Marker recordings or real-time electrograms have not been helpful in this series to identify patients with suspected lead defects prior to the experience of inappropriate ICD discharges.

Alloys↗

PubMed1995

Changes in the amplitude of endocardial electrograms following defibrillator discharge: comparison of two lead systems.

Changes in the amplitude of endocardial electrograms after an unsuccessful shock attempt have been demonstrated to cause failure of redetection of ventricular fibrillation in patients using an integrated sense-pace defibrillating lead system. Thus, the objective of this study was to compare the effects of defibrillator shocks on the amplitude of endocardial electrograms in 26 patients using two different nonthoracotomy systems, a previous lead (model 0062) or a redesigned version (model 0072). At implant, bipolar endocardial electrograms were obtained before each shock application, during initial detection and redetection of ventricular fibrillation in case the applied shock was unsuccessful, and during intervals of 5, 10, 20, 30, 60, and 120 seconds after each shock delivery. No significant difference was noted in endocardial amplitudes between the lead models 0062 and 0072 during baseline sinus rhythm (12.2 +/- 4.6 mV vs 11.4 +/- 3.8 mV), and during initial ventricular fibrillation (7.0 +/- 2.4 mV vs 7.6 +/- 2.3 mV). During redetection of ventricular fibrillation, however, there was a significant difference (P = 0.0006) in endocardial amplitudes (3.4 +/- 1.9 mV vs 6.6 +/- 2.3 mV) between both leads tested. Comparing lead models 0062 and 0072, marked differences were found in endocardial amplitudes during sinus rhythm 5, 10, and 20 seconds after successful arrhythmia termination: 2.8 +/- 1.9 mV vs 8.6 +/- 2.9 mV (P < 0.0001), 4.6 +/- 2.9 mV vs 9.2 +/- 3.2 mV (P = 0.0007), and 6.4 +/- 4.0 mV vs 10.5 +/- 3.6 mV (P = 0.01). At predischarge testing, failure of redetection of ventricular fibrillation was documented in two patients with the lead model 0062 requiring external defibrillation to restore sinus rhythm. These findings demonstrate a significant less postshock attenuation of the endocardial electrogram amplitudes during persistent ventricular fibrillation after an unsuccessful shock attempt as well as during sinus rhythm immediately following an effective shock delivery using the redesigned lead system model 0072 compared to the electrogram amplitudes obtained in patients using the previous lead model 0062.

Adult↗

PubMed1994

Clinical efficacy of shock waveforms and lead configurations for defibrillation.

A randomized, prospective comparison of the defibrillation efficacy of various shock waveforms and nonthoracotomy lead configurations was performed in five distinct patient groups undergoing implantation of a cardioverter defibrillator. In the first group using a bidirectional lead configuration, there was no significant difference in the mean defibrillation threshold (DFT) between simultaneous and sequential monophasic shocks (17.8 +/- 5.8 joules versus 17.3 +/- 2.7 joules). In the second group using a bidirectional lead configuration, the mean DFT was 21.9 +/- 7.3 joules with monophasic shocks and 14.9 +/- 5.0 joules with biphasic shocks (p < 0.001). In the third group using a unidirectional lead configuration, the mean DFT was significantly higher (p < 0.001) with monophasic shocks (22.1 +/- 4.2 joules) compared with biphasic shocks (15.0 +/- 5.4 joules). In the fourth group, an intraindividual comparison with monophasic shock waveforms showed no significant differences in DFT using either a bidirectional (21.3 +/- 5.8 joules) or a unidirectional (21.7 +/- 2.6 joules) lead configuration. In the fifth group, a simplified unipolar transvenous defibrillation lead system ("active can") demonstrated significant lower DFTs (9.7 +/- 3.8 joules) compared with a standardized unidirectional lead configuration (18.0 +/- 6.8 joules). It is concluded that: (1) there seems to be no significant difference in the DFT between simultaneous and sequential monophasic shocks; (2) biphasic waveforms require significantly less energy for defibrillation than their corresponding monophasic waveforms; and (3) the unipolar single-electrode defibrillation system is easy to implant and provides DFTs at energies comparable with epicardial lead systems.

Adolescent↗

PubMed1994

Complications of pacemaker-defibrillator devices: diagnosis and management.

Treatment of resuscitated patients with implantable cardioverter defibrillators has become increasingly more common as a method for the prevention of sudden cardiac death. Major complications such as perioperative death (incidence 2% to 8%), infection (2% to 11%); and lead-related problems (3% to 27%) have been described in previous trials. In our experience with 140 patients, problems were related to leads (n = 11), the device (n = 2), pacing (n = 1), sensing (n = 13), and defibrillation function (n = 5). Additional problems that occurred during the perioperative period included infection (n = 11), hematoma, and seroma (n = 2). Thrombus formation along endocardial leads was observed in 13 of 62 (21%) patients. Different arrhythmias (n = 10), such as sinus tachycardia, atrial fibrillation, and nonsustained, slow or incessant ventricular tachycardia with shock delivery, were also detected. Surgical management (predominantly for the major problems) was used in 31 (48%) patients, drug treatment in 25 (39%), and reprogramming of the device in 24 (38%) patients. All of these problems can result in an increase in mortality rates. This article provides an overview of the complications of cardioverter defibrillator treatment and is based on both published data and our series.

Arrhythmias, Cardiac↗

PubMed1994

Intraoperative laser photocoagulation of ventricular tachycardia.

Mapping-guided laser photocoagulation was used as an intraoperative technique to treat ventricular tachycardia (VT) in patients with ischemic heart disease. Laser irradiation was delivered during VT to sites identified with local diastolic activation or, if VT was not inducible, to sites identified with delayed potentials during sinus rhythm. The group consisted of 12 male and two female patients who ranged in age from 41 to 74 years (mean, 59.9 years). All of the patients had experienced myocardial infarction before surgery; in eight cases myocardial infarction was associated with an anterior wall aneurysm, and in one case it was associated with a posterior wall aneurysm. Identified sites for laser irradiation were restricted to the endocardium in only four patients, whereas six patients showed endocardial and epicardial foci and four of them without circumscript aneurysm were subjected only to epicardial laser photocoagulation. Resection of an aneurysm was performed in nine patients, and additional bypass grafting (one to four grafts) has been performed in 10 patients. There were two perioperative deaths. Laser photocoagulation has proved to be an efficacious method for the surgical treatment of VT. It gives access to epicardial sites and, in particular, allows limited surgery in patients with restricted left ventricular function and no circumscript aneurysm.

Cardiopulmonary Bypass↗