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Biomedical subjects

R Lerch

Publications and source records attributed to R Lerch.

At least 55 records · Page 3Linked to original sources
PubMed1992

Myocardial fatty acid oxidation during ischemia and reperfusion.

Inhibition of fatty acid oxidation is an early event in myocardial ischemia that most likely contributes to tissue injury by the accumulation of potentially toxic intermediates such as acylCoA and acylcarnitine. After reperfusion both myocardial oxygen consumption and fatty acid oxidation may rapidly recover to preischemic levels, even when contractile function remains depressed. The mechanisms underlying the apparent dissociation between contractile function and oxidative metabolism early during reperfusion are still controversial. In isolated rat hearts subjected to 60 min of no-flow ischemia myocardial oxygen consumption and oxidation of palmitate were lowered during reperfusion by 3 mM of NiCl2 and by 6 microM of ruthenium red. The results provide indirect evidence for the hypothesis that intracellular calcium transport may be involved in the mechanisms responsible for the high oxidative metabolic rate early after reperfusion.

Acute Disease↗
PubMed1992

[Assessment of blood flow in hart and large vessels using Doppler color flow mapping].

Two-dimensional echocardiography allows the noninvasive assessment of the morphology and the movement of cardiac structures, including valves and ventricular walls. Color Doppler flow imaging presents a spatial visualization of blood flow, superimposed on two-dimensional echocardiographic images. The color indicates the direction of flow. Turbulent flow is readily identified by the 'mosaic pattern' of the color flow signal. The method facilitates the detection and localization of obstruction to flow, valvular regurgitation or a shunt.

Blood Flow Velocity↗
PubMed1992

Abnormal left ventricular filling pattern in patients with single vessel coronary artery disease: effect of angioplasty.

To study the effect of coronary angioplasty (PTCA) on left ventricular (LV) diastolic filling, mitral Doppler flow tracings of 15 patients with isolated stenosis of the left anterior descending coronary artery (LAD) and normal systolic LV function were recorded before PTCA as well as 24 h and 3 months after successful PTCA. Compared to control subjects, patients with LAD stenosis exhibited an abnormal LV filling velocity pattern before PTCA. The day following PTCA, the ratios of the early peak diastolic velocity to the peak late diastolic velocity and of the time velocity integral of the early diastolic filling phase to the time velocity integral of the late diastolic filling phase were unchanged. Despite the absence of clinical evidence of restenosis, LV filling remained abnormal 3 months after PTCA. The results suggest that abnormalities of the LV filling velocity in patients with isolated LAD stenosis and normal systolic function may persist as long as 3 months after PTCA.

Angioplasty, Balloon, Coronary↗
PubMed1992

Dissociation between contractile function and oxidative metabolism in postischemic myocardium. Attenuation by ruthenium red administered during reperfusion.

The oxidative metabolic rate may be disproportionately high compared with contractile function in postischemic reperfused myocardium. To study the potential involvement of intracellular calcium transport in high energy expenditure after reperfusion, we determined in isolated rat hearts the effect of ruthenium red, an inhibitor of mitochondrial calcium transport, on recovery of contractile function and oxidative metabolic rate. Hearts subjected to 60 minutes of no-flow ischemia exhibited, at 15 minutes after the onset of reperfusion, poor recovery of left ventricular pressure development to only 7% of the corresponding value measured in control hearts (p less than 0.01). However, myocardial oxygen consumption was recovered to 84% of control (p = NS). The ratio of isovolumic contractile performance (expressed as the product of heart rate and left ventricular pressure development) to myocardial oxygen consumption was severely depressed to 6% of control (p less than 0.01). Supplementation of the perfusate with 6 microM ruthenium red during the initial 40 minutes of reperfusion resulted in a reduction of myocardial oxygen consumption to 65% of the value measured after 15 minutes of reperfusion in hearts reperfused without ruthenium red (p less than 0.01), despite a threefold increase of left ventricular pressure development (p less than 0.05). Oxidation of both palmitate and glucose was reduced to a comparable extent by ruthenium red. The ratio of contractile performance to myocardial oxygen consumption increased progressively during infusion of ruthenium red and did not differ further from control hearts after 30 minutes of reperfusion. Cumulative myocardial release of creatine kinase was reduced by 47% (p less than 0.05) in hearts reperfused with ruthenium red-containing medium. The results provide circumstantial evidence for the hypothesis suggesting that enhanced energy expenditure by intracellular calcium transport may be involved in the mechanisms underlying the dissociation between left ventricular performance and myocardial oxidative metabolic rate early after postischemic reperfusion.

Animals↗
PubMed1991

Effect of increasing degrees of ischemic injury on myocardial oxidative metabolism early after reperfusion in isolated rat hearts.

The present investigation studied the effect of increasing severities of ischemic injury on recovery of oxidative metabolism after reperfusion in isolated rat hearts perfused retrogradely with erythrocyte-containing medium. Hearts subjected to 60 minutes of low-flow ischemia (5% of control perfusion) exhibited delayed but sustained recovery of left ventricular pressure development during reperfusion and preservation of ultrastructure delineated with electron microscopy. Immediately after reperfusion, myocardial oxygen consumption returned to control values, well before left ventricular pressure development recovered. Early after reperfusion release of 14CO2 from [1-14C]palmitate was reduced (-53%, p less than 0.01). Conversely, release of 14CO2 from [U-14C]glucose was increased (+131%, p less than 0.05). After 60 minutes of reperfusion 14CO2 release had completely returned to normal for both labeled substrates. Pulse-labeling experiments indicated that during transient depression of [1-14C]palmitate oxidation more tracer was incorporated into myocardial lipid esters, primarily triglycerides. In contrast to hearts subjected to low-flow ischemia, hearts subjected to 60 minutes of no-flow ischemia exhibited poor recovery of contractile function during the reperfusion period. Electron microscopic examination of reperfused hearts showed advanced myocyte damage consistent with irreversible injury. Interestingly, myocardial oxygen consumption in this group also recovered to control values. The substrate pattern during the early reperfusion period was similar to that of hearts subjected to low-flow ischemia. After 120 minutes of no-flow ischemia, recovery of oxidative metabolism was virtually absent. The results indicate a pronounced dissociation between recovery of oxidative metabolism and of contractile function in reperfused myocardium. The oxidative metabolic rate was disproportionately high compared with contractile function, not only in reversibly "stunned" hearts, but also in severely damaged hearts exhibiting signs of irreversible injury.

Acetates↗
PubMed1990

[Physiopathological basis of protection of the ischemic myocardium].

Ischemia initiates a cascade of intracellular events that culminates in the death of the myocyte. Reperfusion of ischemic myocardium is the most efficient way of salvaging jeopardized cells. Additional measures referred to as "myocardial protection" may further reduce ischemic injury, primarily by delaying the progression of cellular damage during ischemia. The pathophysiological aspects of ischemic injury and the possibilities for protection of ischemic myocardium are reviewed. In addition to the "established" methods of myocardial protection, the concept of prevention of "reperfusion injury", presently under experimental investigation, is discussed.

Calcium↗
PubMed1990

Aspergillus endocarditis and myocarditis in a patient with the acquired immunodeficiency syndrome (AIDS). A review of the literature.

We report the post-mortem findings of the case of a 31-year-old male who, through sexual contacts with a female drug addict, was found to be HIV-positive and developed the acquired immunodeficiency syndrome (AIDS) 2 years later. He was treated for various opportunistic infections over the next 7 years when he presented with cardiac abnormalities and multiple cerebral lesions which were responsible for his death. The results revealed Aspergillus fumigatus endocarditis and myocarditis with mycotic thromboembolic extension to the brain, spleen, kidney and pancreas. We review the literature of Aspergillus infection in patients with AIDS and more specifically cardiac involvement with this pathogen.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Early assessment of tissue viability with radioiodinated heptadecanoic acid in reperfused canine myocardium: comparison with thallium-201.

Myocardial scintigraphy with heptadecanoic acid labeled with iodine-123 (123I-HDA) may allow early noninvasive delineation of viable myocardium after reperfusion. In this study myocardial uptake of 123I-HDA was compared with that of thallium-201 in six closed-chest dogs after 5 hours of occlusion followed by 1 hour of reperfusion of the left anterior descending coronary artery. Myocardial blood flow was measured with microspheres, and myocardial viability was assessed by means of triphenyltetrazolium chloride staining. In viable areas of the reperfused region, 123I-HDA uptake, thallium-201 uptake, and myocardial blood flow were similar to those measured in the control circumflex region. However, in infarcted areas they were reduced to 48 +/- 2% (mean +/- SEM; p less than 0.001), 59 +/- 3% (p less than 0.001), and 74 +/- 5% (p less than 0.001) of control values, respectively. Results of multiple regression analysis showed that thallium-201 uptake primarily reflected the level of flow during reperfusion, whereas 123I-HDA uptake was dependent on both myocardial blood flow and viability. At each level of flow, 123I-HDA uptake was significantly lower in infarcted than in viable myocardium. By means of discriminant analysis, 123I-HDA uptake was found to be the single most important predictor of viability, whereas thallium-201 was only of limited importance. Myocardial 123I-HDA uptake greater than or equal to 71% or myocardial thallium-201 uptake greater than or equal to 73% best differentiated viable from infarcted myocardium. According to these criteria, 123I-HDA predicted myocardial viability with a sensitivity of 77%, a specificity of 84% and a predictive accuracy of 81%.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Doppler assessment of left ventricular diastolic filling during brief coronary occlusion.

To assess left ventricular diastolic filling in patients with single-vessel coronary artery disease, Doppler-derived transmitral velocity was studied in 22 normal subjects and in 15 patients with isolated proximal stenosis of the left anterior descending coronary artery (LAD) and normal systolic function of the left ventricle. Transmitral velocity was recorded before and after balloon inflation during coronary angioplasty. At baseline the transmitral velocity pattern in patients with LAD stenosis differed from that of normal subjects with a significant (p at least less than 0.05) decrease in the early diastolic filling phase (E area 0.094 +/- 0.022 m in normal subjects vs 0.078 +/- 0.008 m in patients) and an increase in the late diastolic filling phase (A area 0.034 +/- 0.007 m vs 0.042 +/- 0.008 m). Correspondingly the ratio E area/A area decreased (2.7 +/- 0.51 vs 1.9 +/- 0.4) and the ratio A area/total area increased (0.28 +/- 0.04 vs 0.35 +/- 0.05). During coronary occlusion the E area and the ratio E area/A area decreased further, whereas the A area and the ratio A area/total area increased. The results suggest that patients with single-vessel disease and normal systolic function often exhibit an altered pattern of transmitral velocity even in the absence of overt ischemia, and that during acute regional ischemia early diastolic filling is further compromised with compensatory enhancement of the late diastolic filling phase.

Adult↗
PubMed1987

[Two-dimensional exercise echocardiography. Comparison with electrocardiography, myocardial scintigraphy with thallium 201 and coronary angiography].

Biapical two-dimensional echocardiograms were obtained immediately before and after a bicycle exercise test in 54 patients referred for coronary angiography. Images of adequate quality were recorded in 47 cases (87%), 39 of whom had significant coronary artery disease. All patients also underwent a stress electrocardiogram. In 22 subjects echocardiography and bicycle stress test in the supine position were combined. 23 patients underwent scintigraphy with thallium-201. The sensitivity of rest and exercise echocardiography for the diagnosis of coronary artery disease was 90% and the specificity 63%, compared to 82% and 75% respectively for the electrocardiogram. The sensitivity for the detection of jeopardized myocardium, defined by angiographic criteria, was 75% for the exercise echocardiogram and 65% for the exercise electrocardiogram in the 28 patients without myocardial infarction. In 19 patients with infarction echocardiography detected jeopardized myocardium with a sensitivity of 73%, compared to 53% for the electrocardiogram. In the subgroup of 23 patients studied by thallium-201 scintigraphy, sensitivity for identification of multivessel disease (8 patients) was comparable for both rest and exercise scintigraphy (6/8) and echocardiography (7/8). The specificities were 88% and 94% respectively. Jeopardized myocardium was detected in this subgroup with a sensitivity of 82% by echocardiography, 76% by thallium scintigraphy and 65% by electrocardiography. In conclusion, this study demonstrates that two-dimensional echocardiography can be combined with exercise electrocardiography in one stress test. This improves the diagnosis of coronary artery disease, detection of jeopardized myocardium and identification of patients with multivessel disease.

Adult↗
PubMed1987

Free fatty acid metabolism in "stunned" myocardium.

To assess whether myocardial lipid metabolism is altered in the "stunned" myocardium we have studied the metabolism of (1-14C)-palmitate during reperfusion in a modified rat heart preparation. Hearts were perfused retrogradely at a physiological flow rate (2 ml/min) in a non-recirculating system with erythrocyte-enhanced Krebs-Henseleit buffer containing albumin 0.4 mM, glucose 11 mM, palmitate 0.4 mM and trace amounts of (1-14C)-palmitate. Left ventricular pressure was measured by a latex balloon in the left ventricular cavity. Control hearts were perfused at constant flow for 120 min. To achieve reversible ischaemic damage, myocardial perfusion was reduced by 95% for 40 min, followed by reperfusion at the control flow rate for 60 min (reperfusion group). For comparison, irreversible damage was produced by calcium free perfusion (calcium paradox group). In the reperfusion group, the developed pressure was severely depressed 5 min after reperfusion to 23% of the value in the control group (p less than 0.05) but recovered to 84% (NS) at 60 min. In the calcium paradox group, mechanical activity ceased completely without recovery. Myocardial uptake of (1-14C)-palmitate in the reperfusion group was similar to the control experiments for the entire reperfusion period, whereas a marked depression was observed in the calcium paradox group. 14CO2 production was severely depressed at the onset of reperfusion in both the reperfusion and calcium paradox group to 42% (p less than 0.05) and 29% (p less than 0.05) respectively. In contrast to the calcium paradox group, 14CO2 production in the reperfusion group recovered progressively to 70% (NS) of the control value during the 60 min of reperfusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

[Echocardiographic discoveries in 102 patients with vascular cerebral accidents].

The causes of vascular ischaemic accidents are numerous, and when the brain is involved management is limited to the prevention of similar events. Since cardiac sources of embolism potentially curable, we have prospectively analyzed the results of cardiovascular examinations (including ECG and radiography of the chest) and of echocardiography in 102 patients with cerebral or peripheral vascular ischaemic event in order to determine the impact of echocardiography and the influence of different diagnoses on the need for anticoagulant therapy. Intracardiac thrombi, mitral stenosis, dilated cardiomyopathy, severe left ventricular dysfunction with or without aneurysm and cardiac valve vegetations were regarded as diseases carrying a high risk of embolism, the low risk diseases being mitral valve prolapse, mitral annulus calcification and isolated left atrial dilatation. Atrial fibrillation was treated separately, as it may be associated with several of the diseases listed above. We found 14 diseases with a high risk of embolism (14 p. 100) and 35 diseases with a low risk of embolism (34 p. 100). 10/91 patients with cerebral vascular accident (11 p. 100) and 4/11 patients with peripheral vascular accident presented with a heart disease carrying a high risk of embolism. The most common heart disease with a high risk of embolism (10/14, 71 p. 100) was severe left ventricular dysfunction secondary to a coronary disease or a dilated cardiomyopathy. We did not find more cases of mitral valve prolapse or mitral annulus calcification than in the normal population. 20/29 patients with normal cardiac examination had a normal echocardiogram. The anticoagulant treatment was modified after echocardiography in only one case.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Surgery in primary leiomyosarcoma of the heart.

Primary leiomyosarcoma of the heart is uncommon and we were able to find only 15 cases reported in the literature. Few of these cases were discovered during life and, as a result, even fewer have been treated surgically. We report a case of a right atrial leiomyosarcoma which was proven pathologically (histologically, immunohistochemically and ultrastructurally) after surgical resection. The clinical presentation, morphological, appearances and outcome are compared with those reported in the literature.

Adolescent↗
PubMed1986

Ultrasound fields in attenuating media.

For medical ultrasonic imaging and for nondestructive testing, the attenuation of pressure waves and the resulting shift in wave velocity are important features in commonly used transmission media such as biological tissue. An algorithm for the numerical evaluation of pressure field distributions generated by ultrasonic transducers is presented. The attenuation and dispersion of the sound transmission medium are taken into consideration. The sound fields are computed numerically for continuous wave as well as pulse excitation. The transducer has plane or gently curved geometry and is embedded in a plane rigid baffle. The numerically determined pressure fields are presented as 3D plots, as gray-scale images for a fixed time stamp (like a snapshot), or as isobars regarding the maximum values over time for each local point in the area under investigation. The algorithm described here can be utilized as a tool for design of ultrasound transducers, especially array antennas.

Algorithms↗
PubMed1985

[Prognostic value of bidimensional echocardiography in the acute phase of myocardial infarct].

To evaluate the prognostic value of two-dimensional echocardiography we have studied 43 consecutive patients during the acute stage of myocardial infarction. Recording of sufficient quality where obtained in 74% of the patients. The extent of myocardial damage was estimated by a left ventricular wall motion index (SFR). Regional dyssynergy was found in all patients. Echocardiographic and electrocardiographic infarct localization were in agreement in 93%. Four patients died during hospitalization. The mean SFR in these patients (2.04 +/- 0.46) was significantly higher than in surviving patients (1.16 +/- 0.12; p less than 0.025). The SFR was higher than 2 in three of the four patients who died. All surviving patients had an SFR of 2 or less. In conclusion, two-dimensional echocardiography performed during the first hours of acute myocardial infarction serves to localize the infarct and estimate the extent of myocardial damage. In addition, this technique seems to offer an appropriate means of identifying high risk patients.

Echocardiography↗
PubMed1984

Mixed micells: a new problem-free solution for omega-123I-heptadecanoic acid in comparison.

The most commonly used reagents for solubilization of 123I fatty acids have very serious drawbacks. Human serum albumin solubilizes the fatty acid only slowly and TWEEN 80 is not free of stability problems. Furthermore adverse reactions in human applications cannot be excluded. In comparison, the newly introduced mixed micells look very favourable: fast solubilization, good stability and no adverse reactions. Biodistribution experiments on rats show an adequate performance of the micells . Hitherto this solution has been applied in more than 200 patients without any complication.

Animals↗