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Biomedical subjects

W Flameng

Publications and source records attributed to W Flameng.

At least 217 records · Page 12Linked to original sources
PubMed1981

Ultrastructural correlates of left ventricular contraction abnormalities in patients with chronic ischemic heart disease: determinants of reversible segmental asynergy postrevascularization surgery.

The relationships between structural alterations and left ventricular (LV) contraction abnormalities were studied in patients with coronary artery disease (CAD). Transmural biopsies of the LV anterior free wall were taken during aortocoronary bypass surgery (CABG) in 62 patients. When preoperative anterior wall motion (AWM) was reduced, significant myocardial cell degeneration was found in patients with as well as without previous anterior infarction (MI). The amount of myocardial fibrosis was increased only in patients with ECG evidence of previous anterior MI (p less than 0.001). In a second series of 139 CAD patients, cineventriculograms performed before and 8 months after CABG were examined. In patients with patent grafts to the LV anterior wall not previously infarcted, reduced AWM became normal. In patients with previous anterior MI the outcome of AWM was unpredictable (usually unimproved). Thus the histologic correlate of reduced AWM in segments not previously infarcted was progressive loss of contractile material in otherwise viable myocardial cells. Some reversibility was suggested by restoration of resting function after CABG. Unpredictable results in segments associated with pathologic Q waves appear related to the fibrous component of these previously infarcted areas.

Adult↗
PubMed1981

St. Thomas cardioplegia versus topical cooling: ultrastructural and biochemical studies in humans.

Transmural left ventricular biopsies were studied from 28 patients undergoing cardiopulmonary bypass with anoxic cardiac arrest. The myocardium was protected by topical cooling (20 degrees C) (Group 1, 15 patients) or by cardioplegia with St. Thomas' solution (Group 2, 13 patients). Biopsies were taken at the start of bypass and 3 to 5 minutes after unclamping of the aorta. Mean cross-clamp time was not significantly different between the groups (50 minutes for Group 1 and 53 minutes for Group 2; p greater than 0.05). The ultrastructural changes induced by ischemia and subsequent reperfusion were almost exclusively related to the mitochondria. The degree of mitochondrial damage was evaluated by a semiquantitative analysis based on mitochondrial fine structure. The frequency of severe postischemic mitochondrial damage was significantly higher in Group 1 (20.1% versus 2.7% in Group 2; p less than 0.05). Biochemical analysis of the biopsies indicates that the myocardial concentration of creatine phosphate decreases by about 50% after topical cooling (p less than 0.05). With St. Thomas cardioplegia, no significant change in the tissue level of this high-energy phosphate takes place. The results show evidence of the superiority of the St. Thomas cardioplegia to topical cooling alone.

Adult↗
PubMed1981

Cardioprotective effects of lidoflazine during 1-hour normothermic global ischemia.

The cardioprotective effects of lidoflazine, a drug with calcium homeostatic properties, were investigated in dogs subjected to 1 hour of normothermic global ischemia, followed by reperfusion. None of the eight control dogs could be weaned from the extracorporeal bypass, confirming the severity of the ischemic model. All eight acutely pretreated dogs showed rapid recovery from the prolonged ischemic arrest and could support their own circulation. Recovery of preischemic values was 95% for systolic aortic pressure, 71% for diastolic aortic pressure, 99% for left ventricular dP/dt max and 80% for cardiac output. Light and electron microscopy and calcium cytochemistry were performed on left ventricular biopsies taken before, during and after ischemic arrest. In the control dogs, loss of structural integrity of the sarcolemma and mitochondria was prominent at the end of the ischemic period. Intracellular edema, hypercontraction of sarcomeres and great accumulation of calcium in severely damaged mitochondria occurred after 5 and 30 minutes of reperfusion. In the lidoflazine-treated dogs, such lesions were largely prevented during the ischemic period and completely reversed after reperfusion. These observations suggest that the tolerance of ischemia is markedly augmented by lidoflazine.

Animals↗
PubMed1981

Myocardial protection by lidoflazine during one-hour normothermic global ischemia.

The cardioprotective effects of lidoflazine, a drug with calcium homeostatic properties, were studied in 12 dogs (6 drug-treated and 6 controls) subjected to 1-hour normothermic global ischemia. None of the control dogs could be weaned from the extracorporeal bypass after 30 minutes of reperfusion. In contrast, all acutely pre-treated animals were able to support their own circulation. Recovery of pre-ischemic values in this group was 97 +/- 3% for systolic aortic pressure, 69 +/- 7% for diastolic aortic pressure, 97 +/- 10% for left ventricular pressure, and 84 +/- 11% for cardiac output. Electron microscopy and calcium cytochemistry were done on left ventricular biopsies taken before, during, and after ischemic arrest. In the control group, severe damage to the sarcolemma and the mitochondria was found at the end of the ischemic period and became more prominent after 5 and 30 minutes of reperfusion. There was great accumulation of calcium in the damaged mitochondria. In the lidoflazine-treated dogs, these lesions were largely prevented. These findings suggest a strong cardioprotective effect of lidoflazine during severe myocardial ischemia.

Animals↗
PubMed1980

Ultrastructural and cytochemical correlates of myocardial protection by cardiac hypothermia in man.

We report observations on ultrastructural and cytochemical changes in the myocardium after hypothermic protection in 21 patients who underwent cardiac operation. Two general categories of hypothermic protection were studied. (1) topical cooling during anoxic arrest and moderate general hypothermia (10 patients with aortic valve replacement, Group 1) and (2) intermittent perfusion during moderate general hypothermia combined with topical cooling (11 patients with multiple valve replacement, Group II). Transmural left ventricular biopsies were taken at the start of the cardiopulmonary bypass and shortly after the end of aortic cross-clamping. In Group I (cross-clamp time, 51 +/- 12 minutes) only minor pathologic changes of the myocardial fine structure were found, with no differences among the left ventricular layers. In most mitochondria, structure remained intact but the mitochondrial granules disappeared. Cytochrome-c-oxidase activity was unchanged. In Group II (total cross-clamp time, 83 +/- 16 minutes) the subendocardium was well preserved. Slight subcellular damage comparable with that of resulting from topical cooling was seen in all hearts even after a total cross-clamp period of 106 minutes. Cytochrome-c-oxidase activity was unchanged. In the subepicardium, however, a positive correlation was found between the severity of ultrastructural damage and total cross-clamp time (p less than 0.05). Matrix clearing, damage to the cristae and the mitochondrial membranes, and nuclear abnormalities occurred when the aorta was cross-clamped for morethan 60 minutes. Cytochrome-c-oxidase activities decreased in these samples. It is concluded that: (1) no significant subcellular injury was found in hearts cooled topically during 1 hour of anoxic arrest; and (2) in hearts protected by intermittent perfusion during moderate general hypothermia and additional external cooling, the subendocardium was well preserved for anoxic periods of up to 106 minutes. However, after 60 minutes of aortic cross-clamping subcellular damage increased progressively in the subepicardium.

Aged↗
PubMed1979

Determinants of restricted aorta-coronary bypass graft flow.

Several causes of restricted graft flow in a series of 99 patients could be identified by intraoperative measurements of aorta-coronary graft flow and poststenotic pressure. Mechanical stenosis as well as functional restriction of graft flow caused by competition between vein and native artery flow were noted in cases with a mildly stenotic artery or in cases with multiple coronary stenoses grafted to the same vessel. Also, analysis of regional wall motion showed that graft flow may be restricted when supplying areas with reduced wall motion. Knowledge of preoperative coronary anatomy and left ventricular function and careful intraoperative measurement of graft haemodynamics may aid in distinguishing between technical, functional, and myocardial factors of low graft flow.

Constriction, Pathologic↗
PubMed1979

Failure of aneurysmectomy to improve left ventricular function.

Biplane left ventricular angiography was performed in 22 patients with isolated obstructive disease of the anterior descending branch of the left coronary artery and with an anterior aneurysm following transmural myocardial infarction. Six patients were restudied between 6 and 10 months after aneurysmectomy. Left ventricular reserve was estimated by analysis of a spontaneous postextrasystolic beat. Using angiographic techniques a contractile section, a transitional section, and a noncontractile section were identified. From the surgical patients the excised aneurysm and a transmural needle biopsy of the transitional section were investigated by light microscopy. With increasing volumes of noncontractile and transitional sections, total end-diastolic volume (r = 0.81, P less than 0.001) and end-systolic volume (r = 0.94, P less than 0.001) increased linearly, while the ejection fraction decreased (r = 0.70, P less than 0.001). No relation was found between the combined volumes of the noncontractile and transitional sections on the one hand, and the end-diastolic volume, the end-systolic volume, or the ejection fraction of the contractile section on the other hand. After aneurysmectomy a significant decrease was found in end-diastolic volume (194 to 133 ml/m2, P less than 0.001) and end-systolic volume (124 to 83 ml/m2, P less than 0.001) but no change occurred in ejection fraction (35 to 37%) and left ventricular end-diastolic pressure (23 to 25 mmHg). Surgical resection included part of the transitional section, which before surgery had an average ejection fraction of 27 per cent during a normal beat, rising to 41 per cent in a postextrasystolic beat. The transitional section after surgery now formed a large akinetic area of the anterior wall. We conclude that aneurysmectomy in isolated left anterior descending artery disease with anterior aneurysm fails to improve left ventricular function because the effect of reduction of left ventricular volumes is offset by the destruction of contractile behaviour in the transitional section.

Adult↗
PubMed1979

Impaired left ventricular function in chronic aortic valve disease: survival and function after replacement by Björk-Shiley prosthesis.

Postoperative survival and left ventricular function were studied in 128 patients who underwent isolated aortic valve replacement by the Björk-Shiley valve between 1973 and 1977. The average follow-up was 2.1 years. Patients with associated coronary artery disease or mitral valve disease were excluded. Preoperative ejection fraction ranged from 15-84%. Forty-two patients were restudied by cardiac catheterization 9.1 +/- 1.1 months (mean +/- SEM) after valve replacement. The hospital mortality was 11%. Preoperative type of valve lesion, functional class, cardiothoracic ratio, and ejection fraction (EF) had no significant effect on postoperative survival up to 4 years. After operation, left ventricular mass (LVMI) and peak systolic wall stress (PSWS) fell significantly, while EF and mean normalized systolic ejection rate (MNSER) increased in aortic stenosis and in aortic insufficiency. Neither in aortic stenosis nor in aortic insufficiency was there a significant relation between preoperative ejection fraction and postoperative LVMI, EF, MNSER and PSWS. We attributed this to a marked improvement of left ventricular function in patients with preoperative impaired ventricular function. Six patients with paravalvular leak to restudy has a significantly lower EF and MNSER, and a higher PSWS than patients without leak. Patients without leak had normal EF, MNSER and PSWS when compared with 10 normal persons, but LVMI remained moderately elevated. Postoperative transprosthetic gradient was 11.9 mm Hg (range 0-64 mm Hg). We conclude that impaired cardiac function is completely restored after aortic valve replacement by Björk-Shiley valve, if valve function is good. Patients with impaired cardiac function preoperatively did not have a poorer prognosis after operation than patients with normal function.

Adolescent↗