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Biomedical subjects

H H Scheld

Publications and source records attributed to H H Scheld.

At least 253 records · Page 14Linked to original sources
PubMed1993

Surgical experience with defibrillator implantation using nonthoracotomy leads.

Between October 10, 1989, and June 17, 1991, 109 patients with life-threatening ventricular arrhythmias received an implantable cardioverter-defibrillator at our institution. In 50 patients, nonthoracotomy lead systems consisting of a subcutaneous chest wall patch electrode near the cardiac apex and one (Cardiac Pacemakers, Inc: Endotak C) or two (Medtronic: Transvene) transvenous electrodes were tested. The mean ejection fraction was 0.44 +/- 0.15 with a range from 0.19 to 0.81. Twenty-four patients had a history of open heart operation. In 43 patients the nonthoracotomy lead system was implanted, whereas in 7 patients epicardial patch lead systems were required due to elevated defibrillation thresholds during nonthoracotomy lead testing. There was one perioperative death unrelated to the operative procedure (hydrocephalus internus). Hemorrhage from the subcutaneous patch pocket or the device pocket that required reintervention occurred in 4 patients. During a mean follow-up of 13 +/- 5 months (range, 4 to 26 months) no dislocation of an endocardial lead, insulation defect, or lead fracture has been observed. In 1 patient, the lead system had to be removed due to infection of the subcutaneous patch pocket. The cardiovascular survival rate was 98% at 12 and 18 months, and freedom from sudden cardiac death was 100% at 6 and 12 months. In conclusion, defibrillator implantation using nonthoracotomy lead systems is feasible with a success rate of 86%, and during short-term follow-up no problems related to the lead system such as dislocation, fracture, or insulation defect have occurred.

Adolescent↗
PubMed1993

Pulmonary artery origin of the left coronary artery: diagnosis by transoesophageal echocardiography in infancy.

In two infants the anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA) was detected prospectively by transoesophageal echocardiography (TEE). Colour flow mapping and pulsed Doppler ultrasound revealed a predominant right-to-left shunt from the pulmonary artery to the left coronary artery. These findings were confirmed by angiography. Transthoracic echocardiography (TTE) failed to show the anomalous origin of the left coronary artery or any abnormal pulmonary flow pattern. TEE may be useful in the diagnosis of ALCAPA in selected cases, when TTE is inconclusive.

Coronary Vessel Anomalies↗
PubMed1993

Non-destructive evaluation of prosthetic heart valves by holographic interferometry.

Dysfunction of prosthetic heart valves is a common complication after heart valve replacement, affecting both biologic and mechanical prostheses. A preoperative, non-destructive test of each individual valve may help to prevent the implantation of a valve which has material weaknesses. To this end we developed a technique for testing heart valve prostheses by holographic interferometry. The advantage of this technique is that it provides a non-contact, non-destructive, highly sensitive three dimensional analysis of the valve under loading. Samples of several mechanical and biologic valve substitutes were investigated. Deformations of the valve, due to small pressure differences applied to the samples in a specially developed test chamber, were recorded by double exposure holography. A fringe pattern superimposed on the image of the valve reconstructed from the hologram clearly indicates the presence of even the slightest defect in the valve material. Our experimental results demonstrate the ability of non-destructive holographic screening testing to detect defects or weaknesses which may potentially lead to dysfunction in replacement valves.

Animals↗
PubMed1993

Non-destructive evaluation techniques for prosthetic heart valves based on hologram interferometry. Part I.

The development of a technique applying hologram interferometry, which is a non-destructive, non-contact, full-field, highly sensitive method is reported. The valve under investigation is placed in a test chamber which has windows providing optical access. Deformations of the valve leaflets due to pressure loading are recorded by hologram interferometry. The resulting interferogram clearly indicates the existence of any defects or structural anomalies which may be present in the valve material. Three modifications to this technique, intended for qualitative and quantitative non-destructive valve screening tests are described. The proposed technique is expected to become an effective means of detecting hidden defects of replacement heart valves; it is thus considered as a prospective tool for quality control, particularly in the manufacture of bioprosthetic valves, where initial sites of late calcification and degeneration might be identified. The application of holographic non-destructive testing may therefore substantially improve the quality and durability of heart valve substitutes.

Artifacts↗
PubMed1993

Non-destructive evaluation techniques for prosthetic heart valves based on hologram interferometry. Part II: Experimental results and clinical implications.

Non-destructive evaluation by hologram interferometry of seven mechanical and seven bioprosthetic valves was carried out. Irregular fringe patterns suspect of intrinsic valve anomaly which may lead to later dysfunction were detected in one mechanical and six bioprosthetic valves. Histologic examination of two bioprosthetic valves revealed focal degeneration, especially in the fibrosa, in those parts of the leaflets that had obvious anomalies on the holographic interferograms. It was shown that the flow turbulences caused by prosthetic valves can also be evaluated using hologram interferometry. The experimental results, obtained with six different types of prostheses (Lillehei-Kaster, Bjork-Shiley, Omnicarbon, St. Jude Medical, Carpentier-Edwards S.A.V. and Valcor), demonstrated the applicability of this technique to both mechanical and bioprosthetic valves. Carrying out non-destructive screening tests for heart valve prostheses may prevent the implantation of potentially dysfunctional devices.

Animals↗
PubMed1993

[Therapy of ventricular tachyarrhythmia with implantable cardioverters/defibrillators--mortality and complications using epicardial electrodes].

Technical improvements of third generation implantable cardioverter defibrillators (ICD) like antitachycardia pacing modalities lead to an extended use of ICDs, not only in patients with aborted sudden cardiac death, but also in patients with hemodynamically tolerable ventricular tachycardia. In addition, anticipated results of current prospective studies might indicate the prophylactic use of ICDs in patients with high risk for sudden cardiac death, but without documented ventricular tachyarrhythmias. This report reviews mortality and complications associated with the ICDs with epicardial defibrillation leads. Mortality is separated in cardiac death, sudden cardiac, arrhythmogenic "not so sudden" cardiac death, and overall mortality. Pulmonary complications and infections are related to the underlying disease and the surgical procedure. Device- and lead-related complications, high defibrillation thresholds, pacemaker interactions, inappropriate shocks, arrhythmic effects, syncope, and psychosocial problems are reported, respectively.

Adolescent↗
PubMed1992

Technique of aortic valve replacement with the Edwards stentless aortic bioprosthesis 2500.

Aortic valve replacement with a stentless device ought to result in superior hemodynamic function, because obstructing stents and sewing rims are eliminated. From 15 June 1991 to 15 October 1991, 15 patients underwent aortic valve replacement with the newly designed Edwards stentless aortic bioprosthesis 2500. Patients' ages ranged from 51 to 70 years (mean 61 years). Preoperatively 4 patients presented with aortic regurgitation, 7 with aortic stenosis and 4 with combined lesions; 7 patients were male and 8 female. No additional cardiac or noncardiac diseases were encountered. The operations were performed under normothermic extracorporeal cardiopulmonary bypass and cold cardioplegic cardiac arrest. The implanted valves ranged from 21 mm to 27 mm in diameter. Ten patients received a subcoronary implantation with the lower row of stitches made up of interrupted sutures and the upper row of a continuous suture. In 5 patients the so-called miniroot technique was used, also with lower interrupted sutures and running upper sutures, after adaptation of coronary ostia to the performed openings in the graft. Aortic cross-clamp time ranged between 73 min and 94 min (mean 82 min). There was no operative mortality or morbidity. Postoperative echocardiography showed no signs of aortic valve regurgation in any patient and continuous wave-Doppler measurements showed that resting pressure gradients across the aortic valve were absent or low. Our preliminary experiences with a stentless aortic xenograft valve show that in presence of an increased cross-clamp time an improved hemodynamic function will be obtained. Further studies will be needed, however, to establish the long-term behavior of this device.

Aortic Valve Insufficiency↗
PubMed1992

Echinococcal cyst of the interventricular septum: a rare cause of myocardial ischemia.

A 30-year-old woman developed ischemia-like chest pain due to myocardial compression by an intracardiac cyst. The cyst was located in the interventricular septum. Its etiology could not be ascertained despite several diagnostic measures but exstirpation was indicated by the clinical symptoms. Intraoperatively the diagnosis of echinococcosis was established. The cyst was extirpated in toto without perforation of the thinned interventricular septum. Postoperatively the patient was symptomfree.

Adult↗
PubMed1992

Aortic annular enlargement with the use of a homograft valve.

A technique of annular enlargement for use in homograft aortic valve surgery is described. Potential advantages of this technique, that allows convenient valve sizes in small aortic annuli, lie in the pediatric group of patients requiring aortic valve replacement.

Aortic Valve↗
PubMed1992

Implantation of a cardioverter/defibrillator in the subpectoral region combined with a nonthoracotomy lead system.

An implantable cardioverter defibrillator was placed into a subpectoral pocket via the incision for cephalic venotomy during implantation of a nonthoracotomy lead system. The approach obviated another incision and subcutaneous tunneling of the leads. There were no perioperative complications and after 6 months of follow-up, the patient continues to tolerate the device satisfactorily.

Electric Countershock↗
PubMed1992

Role of ventricular tachycardia surgery and catheter ablation as complements or alternatives to the implantable cardioverter defibrillator in the 1990s.

Although the implantable cardioverter defibrillator is used increasingly, other nonpharmacological approaches have their indications and merits. Furthermore, as the natural history of ventricular tachyarrhythmias or their underlying structural cardiac abnormality, i.e., coronary artery disease, dilated cardiomyopathy, arrhythmogenic right ventricular disease, etc. change, the mode of therapy may be modified accordingly. Because of the disappointing results of the CAST study in previously asymptomatic patients after myocardial infarction and the evidence that failure of one or two antiarrhythmic drugs tested by programmed ventricular stimulation in patients with documented sustained ventricular tachycardia or fibrillation predicts further drug failure, there will be a significant increase in the use of implantable cardioverters defibrillators in the 1990s. However, care should be taken to avoid inappropriate use of these devices.

Adult↗
PubMed1992

Aortic valve replacement with stentless xenografts.

Between 15th June 1991 and 15th August 1992, 40 patients underwent aortic valve replacement with the newly designed Edwards stentless aortic bioprosthesis 2500. The patients' ages ranged from 24 years to 80 years (mean 60.3 years). Preoperatively, 17 patients presented with pure aortic stenosis, three with aortic regurgitation and 20 with mixed lesion. The operations were performed with normothermic extracorporeal cardiopulmonary bypass and cold cardioplegic arrest. The implanted valves ranged in diameter from 21 mm to 27 mm. Ten patients received a subcoronary implantation, with the lower row of sutures being interrupted and the upper being continuous. The so-called miniroot technique was used in the other 30, also involving lower interrupted and running upper sutures after adaptation of the coronary ostia to the preformed openings in the graft. The aortic cross-clamp time ranged from 51 minutes to 94 minutes (mean 71 minutes). There was no operative mortality but three patients died early after the operation due to cardiac tamponade, sepsis and pneumonia. There was no late mortality or morbidity in the surviving patients up to 16 months postoperatively. Echocardiography, performed at discharge and twice a year thereafter showed no signs of significant valve incompetence in any patient, and continuous wave Doppler measurements indicated that resting pressure gradients across the aortic valve were low or absent. Our preliminary experience with the stentless aortic xenograft shows improved hemodynamic function as compared to stent mounted xenografts or mechanical prostheses. Further studies are needed, however, to establish the long-term performance of this device.

Adult↗