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Biomedical subjects

G Bloch

Publications and source records attributed to G Bloch.

At least 19 recordsLinked to original sources
PubMed1992

[Towards an integrated protection of heart grafts].

In an attempt to provide a consistent protection of cardiac allografts during the sequence of events inherent in transplantation procedures, we developed two preservation solutions of which one is used for initial arrest, storage and cardioplegia during graft implantation, whereas the other serves as initial reperfusate. The formulations of these solutions are closely interrelated and their design has integrated the basic principles of organ preservation with those of myocardium-specific metabolism. Based upon experimental studies in the isolated rat heart model, this integrated approach has yielded better functional recoveries than conventional preservation protocols.

Animals↗
PubMed1992

Normothermic cardioplegia: is aortic cross-clamping still synonymous with myocardial ischemia?

The enthusiastic clinical reports on normothermic blood cardioplegia contrast with the paucity of data on the myocardial metabolic effects of this technique. The present study was therefore designed to assess whether normothermic blood cardioplegia really provides an aerobic environment during aortic cross-clamping. Thirty-one patients undergoing coronary (16 patients), valve (13 patients), and transplantation (2 patients) procedures were given continuous normothermic blood cardioplegia through the coronary sinus. Myocardial metabolism was assessed either immediately before aortic unclamping (16 patients) by collecting blood simultaneously from the cardioplegia infusion line and the aortic effluent or during reperfusion (15 patients) by collecting blood simultaneously from the radial artery and the coronary sinus. All samples were assayed for markers of anaerobiosis (blood gases, lactates), leukocyte activation (elastase), and lipid peroxidation (malondialdehyde, vitamin E). At the end of arrest, oxygen extraction was low, whereas the production of lactates was small, thereby suggesting the efficacy of normothermic blood cardioplegia in maintaining a predominantly aerobic metabolism. This was confirmed by postarrest data, as oxygen extraction measured immediately after cross-clamp removal was unchanged from prearrest values, whereas lactate metabolism yielded transient and limited production followed by prompt recovery of normal extraction patterns. There was no release of elastase from the myocardium, which suggests adequate protection of the coronary endothelium from ischemic injury and the related increase in leukocyte activation. Likewise, postarrest coronary sinus concentrations of malondialdehyde and vitamin E were identical to the respective arterial concentrations, thereby ruling out the occurrence of intramyocardial lipid peroxidation at the time of reperfusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Is the internal mammary artery an acceptable graft in the elderly patients with left main coronary artery disease?

Age over 70 years and critical stenosis of the left main coronary artery trunk are two situations in which the use of the internal mammary artery has been questioned. Because the coexistence of these two conditions is increasingly seen, we reviewed our experience with 53 patients 70 years of age or older that underwent myocardial revascularization for left main disease. In 17 patients, the left anterior descending coronary artery was grafted with the left internal mammary artery whereas the 36 remaining patients were exclusively revascularized by means of saphenous vein conduits. There was no significant difference in postoperative mortality or morbidity between the two patient groups. We conclude that elderly patients with left main disease should be offered the benefits of a mammary artery graft provided they are hemodynamically stable.

Age Factors↗
PubMed1992

Pretreatment with captopril improves myocardial recovery after cardioplegic arrest.

Among the interventions designed to limit postischemic oxidative injury, those that enhance the myocardial content of thiol groups are attractive because thiols are powerful antioxidant. Indeed, part of the protection afforded by the angiotensin-converting enzyme (ACE) inhibitor captopril in regional myocardial ischemia is attributed to its thiol group. This study assesses the effects of captopril in a surgically relevant model of global ischemic arrest. Thirty rats were implanted subcutaneously (s.c.) with osmotic pumps that allowed continuous delivery of captopril (total dose 75 mg), enalapril (a nonthiol-containing ACE inhibitor, total dose 7.5 mg) or saline in 48 h. Drug concentrations were equipotent in their effect on angiotensin I (ANGI) pressor response. Hearts were then excised, perfused under isovolumic conditions, and subjected to 90-min cardioplegic arrest at 30 degrees C followed by 1-h reperfusion. Pre- and postischemic coronary flows were significantly higher to a similar extent in the two drug-pretreated groups than in controls. However, captopril-pretreated hearts had the best recovery of contractility (dP/dtmax; 3,590 +/- 74 versus 2915 +/- 64 mm Hg s-1 in the enalapril group, p less than 0.001), and diastolic pressure (13.7 +/- 0.9 mm Hg vs. 20.0 +/- 1.6 mm Hg in the enalapril group, p less than 0.05). We conclude that pretreatment with ACE inhibitors improves myocardial recovery after cardioplegic arrest and that captopril is more effective than enalapril. The additional protection afforded by captopril was not flow mediated, suggesting that the cardioprotective effects of this drug not only involve an ACE inhibition-dependent coronary vasodilation but could be related to a thiol-dependent limitation of oxidative injury.

Animals↗
PubMed1991

Diagnosis of muscular glycogenosis by in vivo natural abundance 13C NMR spectroscopy.

Natural abundance 13C NMR (nuclear magnetic resonance) spectroscopy was used to distinguish patients suffering from muscle glycogenosis type V (McArdle's disease) from normal subjects by measuring their muscle glycogen content at rest. Proton-decoupled 13C spectra were obtained in 10-15 min from calf muscles at rest. The ratio of the glycogen/creatine signal areas was 12.9 +/- 1.7 in four McArdle's disease patients and 2.0 +/- 0.7 in seven normal subjects. This technique thus allows the non-invasive diagnosis of muscle glycogenosis.

Adult↗
PubMed1979

[Technical development in aortocoronary bypass: multiple outlet saphenous vein graft].

The technique of multiple outlet saphenous vein grafting with one or several alternating lateral anastamoses was used in 43 patients over a one year period; over half the patients had triple vessel disease, one third had double vessel disease; a total of 128 coronary arteries were revascularised 2.9 arteries per patient, with 60 side to side anastamoses, 1.4 per patient. The technique of this type of bypass necessitates paying particular attention to avoid kinking or twisting of the graft. The blood flow through multiple outlet graft is on average significantly greater than in the classical types of graft, and is one of the main points in favour of this technique and in keeping the graft permeable in the long term. The short term results of this technique are good with a hospital mortality of 4.6% and a peri-operational infarction rate of 6.9%, figures which are comparable with the results of classical bypass grafting techniques in multivessel coronary artery disease.

Adult↗
PubMed1978

[Pathological data of 92 rheumatic mitral valve after surgical ablation : comparison with pre-operative echocardiography results].

The echocardiographic information obtained pre-operatively with an electronic linear scanning system (Multiscan) was compared with the results of pathological examination of the excised mitral valve in 92 patients, and showed a close correlation. The way in which the pathological changes influence the various parameters usually used to distinguish this type of rheumatic valvular disease is demonstrated. Two-dimensional imagery provides precise information : this is shown by comparison of the still frames of the videoscopic recording and the photographs of the corresponding pathological specimens. Valve thickness, length and thickness of the chordae, calcification, mitral valve surface and commissural separation are well shown, especially at the anterior leaflet. Study of transverse incidences seems the most reliable method of estimating mitral valve area. Systolic separation of mitral valve echos, according to the usual criteria, is a good sign of associated mitral incompetence and was found in 83% of cases of mixed mitral valve disease. The mean values of anterior mitral leaflet excursion, diastolic slope and opening speeds were compared in three groups of mitral stanosis with preferential antatomical features and a control group of pure mitral stenosis with supple valves. No individual parameter was found to be specific for a particular antatomical feature, showing multiple correlations to be indispensable. The difficulty of diagnosis by isolated traditional echocardiography is confirmed and the association of two dimensional imagery would seem essential not only in making the diagnosis but also in the pre operative work up.

Adolescent↗
PubMed1978

[Resections of the left ventricle in the surgical treatment of parietal sequelae of myocardial infarct].

Resection of left ventricular tissue seems to be playing an increasing part in the treatment of the sequelae of myocardial infarction. In a total of 700 patients who underwent surgery for some aspect of coronary atherosclerosis, 40 underwent resection of left ventricular tissue. In the majority of cases, diagnosis rested on left ventricular cine-angiography and in 3 cases this had to be carried out as an urgent procedure with circulatory assistance using diastolic counter-pressure (DCP) from an intra-aortic balloon. A selective contrast technique for the two coronary arteries was used whenever possible. The surgical anatomy of the lesions indicates a difference between a localised dyskinesia and diffuse dyskinesia, the latter having a severe effect on left ventricular function. In a group of localised dyskinesias, the territory supplied by the anterior descending artery was by far the most frequently affected. Resection of left ventricular tissue was associated with a myocardial bypass revascularisation procedure in 9 cases, valve repair in 7 cases, and closure of a septal perforation in 3 cases. The total inpatient mortality rate is still quite high (23.1%) because of the severity and widespread nature of the coronary disease. However, the mid-and long-term results are good, the criteria being functional improvement and the actuarial 4-year survival rate.

Adult↗
PubMed1978

[The "small aortic ring." Hope for a surgical solution].

The "small aortic ring" was until recently an unresolved problem for surgeons operating on the aortic valves. It used to contraindicate valve replacement in the child, and sometimes led to the insertion of too small a valve in the adult. Some hope of a solution has appeared in the form of three new techniques: enlargement of the aortic ring over the mitral valve, aorto-ventriculoplasty, and apico-aortic shunt. Two adults have had the ring enlarged above the mitral valve with good results in both cases. Five children have had an aorto-ventriculoplasty with good results in two cases, post-operative atrio-ventricular block in one, and two deaths, one early and the other late. These deaths appear to be more closely related to the severity of the initial lesion and to the degree of decompensation of the myocardium than to the operation itself. There are advantages and problems with this technique. An attempt has been made to systematise indications for treatment as a function of the lesions and the state of the patient.

Adolescent↗
PubMed1977

[Mitral replacement using a ball-valve prosthesis under hypothermic protection of the myocardium. 230 cases].

A series of 230 mitral valve replacements using exclusively the Starr-Edwards ball valve prosthesis is presented. These 230 patients underwent surgery over a 4 year period, a uniform operative technique being used. Its essential feature was the use of a standardised technique for protection of the myocardium based upon continous clamping of the aorta and deep hypothermia at around 15 degrees. The technique of myocardial hypothermia, already reported, is briefly reviewed. The results are analysed, in the short and long term. Overall hospital mortality was 6.9 per cent, including multiple valve replacements and combined coronary surgery. The total number of thrombo-embolic complications was 8, including 1 early thrombosis out of 230 patients - i.e. 0.4 per cent and 7 late thrombo-embolic episodes out of 180 patients followed up for 1 month to 4 years - i.e. 3.8 per cent. Secondary and late mortality was 11 cases out of 180 patients. The survival rate at 4 years was 78 per cent by actuarial calculation, including operative mortality. These results justify the continued use of ball prosthesis, the long term thrombo-embolic risks of which are equal to or less than those of disc prosthesis, and the resistance of which to wear and tear is shown by the long postoperative survivals.

Adult↗