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Biomedical subjects

P Assayag

Publications and source records attributed to P Assayag.

At least 37 records · Page 2Linked to original sources
PubMed1997

Differential regulation of matrix metalloproteinases associated with aging and hypertension in the rat heart.

We compared two models of cardiac fibrosis in which collagen synthesis is controlled at different levels. Regulation is pretranslational in aldosterone-salt-induced hypertension in young rats and posttranslational in 24-month-old rats. However, little is known about the role of matrix metalloproteinases (MMP) in fibrosis development. Ventricular MMP activities were studied by zymography, and MMP-2 and MMP-1 mRNA levels were determined using slot-blot and ribonuclease protection assay, respectively. After 1 month of aldosterone-salt treatment, proMMP-2, MMP-2, and proMMP-1 collagenolytic activities and their gene expression were unchanged compared with sham-operated rats. After 2 months, total MMP-2 activity was increased by 40% with parallel stimulation of its gene expression. These changes were localized by in situ zymography within the media of coronary vessels. These results suggest that MMP play a prominent role in vascular remodeling during the first steps of hypertension. During aging, however, there were 40% and 45% decreases in MMP-2 and proMMP-1 activity, respectively, with a corresponding down-regulation of MMP-2 mRNA. These observations suggest that depression of the degradative pathway is partly responsible for age-associated fibrosis. Thus, MMP have differing involvements in the cardiac remodeling associated with hypertension or aging.

Aging↗
PubMed1997

[Anatomoclinical study of aortic insufficiency in atrophic polychondritis. Apropos of a case].

The authors report the anatomo-clinical features of aortic insufficiency complicating atrophic polychondritis, a rare inflammatory disease affecting mainly cartilaginous tissues. This case illustrates the inflammatory changes of the aortic wall, particularly progressive during this disease, responsible for aortic insufficiency and aneurysmal dilatation of the ascending aorta which required aortic valve replacement and prosthetic replacement of the ascending aorta. Histological analysis showed inflammatory lesions of the aortic wall comparable to the cartilaginous lesions described in this condition and suggesting a common physiopathogenic mechanism.

Adult↗
PubMed1997

Utility of indium-111-antimyosin scintigraphy for diagnosis of myocardial damage in systemic sclerosis.

The diagnosis of myocardial disease related to systemic sclerosis is often difficult, but it is clinically relevant since the occurrence of a specific ventricular dysfunction is of poor prognosis. This article reports a case of systemic sclerosis with a subacute episode of myocardial disease assessed by 111In-antimyosin antibody, a specific marker of the necrotic myocardial fiber.

Adult↗
PubMed1997

[Myocardial viability: results of myocardial revascularization during the acute phase of myocardial infarction].

Complete coronary reperfusion after thrombolysis or primary angioplasty is associated with limitation of infarct size and conservation of left ventricular function. The area of viable myocardium recovers its function secondarily, the amount of recovery being related to the precocity of reperfusion. Patients with a patent artery in the acute stage do not all recover segmental contraction to the same extent. There are considerable discrepancies between coronary patency and myocardial perfusion. Myocardial perfusion, measured in the acute phase by myocardial contrast echocardiography is the best predictor of preservation of function. This suggests that microvascular lesions are a sign of the extent and irreversibility of myocardial damage. Modern treatment of infarction should not only restore coronary patency but also ensure effective myocardial reperfusion. The factors which determine recovery of ventricular function after reperfusion during the acute phase, are, in addition to early and complete coronary recanalisation and effective myocardial reperfusion: short duration of ischaemia, small size of the area at risk, collateral circulation, ability of the myocardium to withstand ischaemia, limitation of reperfusion injury. Other factors (smoking, pre-infarction angina, the occluded artery or method of reperfusion) may play a role but the role of confounding factors is always difficult to exclude.

Coronary Angiography↗
PubMed1996

Tricuspid autograft for mitral-valve repair.

BACKGROUND: Transferring the posterior leaflet of the patient's own tricuspid valve with its subvalvular apparatus to the mitral valve is a new technique that allows a conservative approach to mitral-valve repair. The technique is based on the knowledge that the tricuspid valve can be remodelled from tricuspid to bicuspid, with a very low risk of significant dysfunction. METHODS: We describe six patients (age range 20-70 years) with mitral insufficiency in whom we have used the technique. FINDINGS: All patients survived the operation and were in sinus rhythm. Transoesophageal echocardiography before discharge showed trivial or no regurgitation at the site of mitral repair. Before operation, all patients were in New York Heart Association class III-IV; at follow-up after 6-13 months all patients were in class I-II. INTERPRETATION: Compared with using segments of mitral homografts in similar situations, the intraoperative availability of the tricuspid's viable natural chordae and valvular leaflet means that there are no immunological disadvantages to the procedure. With this new operation, the patient is his own tissue bank.

Adult↗
PubMed1996

[Mitral valve repair by transfer of the posterior tricuspid leaflet and its chordae].

Mitral valve repair was performed in six patients by transferring the posterior tricuspid leaflet with its sub-valvular apparatus onto the mitral valve. This new technique considers the tricuspid valve as the patients own tissue bank where the posterior leaflet and eventually the adjacent part of the anterior leaflet is used as a "donor" valve, based on the knowledge that the right atrio-ventricular valve can be efficiently repaired with a very low risk of significant dysfunction. The mitral repair consists of incorporating the tricuspid autograft by securing the tricuspid papillary muscle to the mitral papillary muscle and by suturing the leaflet tissue where required. A mitral annuloplasty ring reinforces the repair. The tricuspid valve is subsequently repaired by annular plication and leaflet suture. A tricuspid ring is necessary to maintain efficient remodeling. The six patients ages ranged from 20 to 70 years. A etiology, was rheumatic in the first case and degenerative in the following. In three cases, sterilised endocarditis was responsible for ruptured chordae and leaflet destruction. The mitral insufficiency was located in a commissural area in 4 cases, and was due to a widespread posterior prolapse in 2. Post-operative control transesophageal echocardiography confirmed the excellent results of the repair and proved that, in selected cases, the tricuspid leaflet inserted onto the mitral apparatus is very efficient in correcting mitral insufficiency, without causing significant tricuspid impairment. With a 3 to 7 month follow-up, the results are stable.

Adult↗
PubMed1996

[Repair of post-infarction left ventricular wall ruptures by biological glue and a flap from the pericardium. Results from 2 to 10 years].

The authors report their experience with a simple and efficient technique for repair of left ventricular free wall rupture complicating myocardial infarction. The technique consists, with the aid of cardiopulmonary bypass, in suturing a plaque of the patients own pericardium (6 to 8 cm in diameter) to the more normal tissue encircling the pathologic myocardium, and by injecting five ml of human fibrin glue as a cement under the pericardium to reinforce the remair and prevent leaking throughout the suture line. With a 10 year follow-up, we are able to be confident with the long term results. The five patients, at the time of operation were aged 46 to 74 years. The post-operative results and the annual echocardiographic controls have proved the technique to be sound without recurrences and without late complications such as pseudo aneurysms at the site of the repair.

Aged↗
PubMed1995

[Unstable angina. Physiopathology, clinical course and therapeutic principles].

The pathogenic mechanism of unstable angina, a clinical expression of coronary heart disease, is similar to that of myocardial infarction. The main event is the instability of the atheromatous plaque adhering to the coronary intima leading to thrombosis and occlusion. Clinical manifestations can be severe since fatal or non-fatal myocardial infarction occurs in 3.9% and 5.4% of the case respectively. Adapted medical treatment can stabilize the situation in most patients, justifying early preventive treatment. Moreover, it has been estimated that a premonitory phase of angina had gone unnoticed or undiagnosed in one-half of all myocardial infarcts. In nearly all patients with unstable angina, coronarography is of major importance for rapidly defining an adapted therapeutic strategy. Myocardial revascularization (especially by angioplasty) is often needed to limit the risk of major cardiac events occurring within a short or moderate delay. Unfortunately, these procedures carry a supplementary risk of thrombosis. Thus the emphasis placed on measures capable of improving the anti-thrombotic risk in unstable angina by using new antiplatelet agents, or for certain patients at high risk of a major cardiac event, antithrombosis agents. Finally, the search for compounds capable of stabilizing the previously formed atheromatous plaque (and thus avoiding rupture) is a prime objective for an overall management strategy for patients with coronary heart disease.

Angina, Unstable↗
PubMed1995

[Stress ultrasonography with dobutamine in the diagnosis of coronary disease].

Digital stress echocardiography (DSE) with dobutamine infusion has recently emerged as an attractive alternative to exercise stress testing for evaluating coronary artery disease. DSE seems particularly useful in the diagnosis or the assessment of ischemia in patients unable to exercise or when the test is difficult to interpret. DSE has also proved to be useful in patients undergoing preoperative evaluation of cardiac risk. The assessment of residual myocardial viability in patients with previous myocardial infarction is another promising development. After a description of the methodology of dobutamine stress echocardiography, this article reviews the experience obtained to date with this technique in the diagnosis and the evaluation of coronary artery disease.

Cardiotonic Agents↗
PubMed1995

Molecular and cellular biology of the senescent hypertrophied and failing heart.

During aging, experimental studies have revealed various cellular changes, principal among which is myocyte hypertrophy, which compensates for the loss of myocytes and is associated with fibrosis. The expression of alpha-myosin heavy chain is replaced by that of the isogene beta-myosin, which leads to decreased myosin adenosine triphosphatase (ATPase) activity. In consequence, contraction is slower and more energetically economical. The Ca(2+)-ATPase of the sarcoplasmic reticulum and Na+/Ca2+ exchange activity are decreased, which probably explains the reduced velocity of relaxation. Membrane receptors are also modified, since the density of both the total beta-adrenergic and muscarinic receptors is decreased. The senescent heart is able to hypertrophy in response to overload and to adapt to the new requirements. Similar alterations are observed both in the senescent heart and in the overloaded heart, in clinical as well as in experimental studies; however, differences do exist, especially in terms of fibrosis and arrhythmias.

Adaptation, Physiological↗
PubMed1995

Nonlimited exercise test combined with high-dose dipyridamole for thallium-201 myocardial single-photon emission computed tomography in coronary artery disease.

Clinical, electrocardiographic, and thallium-201 single-photon emission computed tomography data were evaluated in 397 consecutive patients divided into 3 groups according to coronary hyperemic stimulation: 186 patients (group I; Ex) had maximal symptom-limited exercise ergometric stress testing, 93 patients (group II; Dip) had intravenous dipyridamole (0.7 to 0.8 mg/kg) stress testing, and 118 patients (group III; Dip+Ex) had dipyridamole (0.7 to 0.8 mg/kg) plus nonlimited (i.e., symptom-limited) exercise stress testing, achieving a maximal workload (mean +/- SD) of 102 +/- 37 W. Clinical tolerance was higher in Ex than in Dip groups (p < 0.01), and tended to be higher in Dip+Ex than in Dip groups (p = NS). Image quality--as judged by signal-to-noise ratios--was superior in Ex and Dip+Ex groups when compared with the Dip group (p < 0.01). Chest pain and electrocardiographic positivity were more frequent in the Dip+Ex group than in the Dip group (p < 0.05), despite more extensive coronary artery disease (CAD) in the Dip group; and reversible scintigraphic defects were more frequent in Dip+Ex versus Dip (p < 0.01) and in Ex versus Dip groups (p < 0.05) in patients with established CAD, as well as for the whole group. We conclude that, in patients unable to achieve 85% of their maximal predicted heart rate, the combination of high-dose dipyridamole plus nonlimited exercise stress testing is superior to dipyridamole stress testing alone, and comparable to maximal exercise testing.

Aged↗
PubMed1995

The O'Brien-Angell stentless porcine valve: early results with 150 implants.

From August 1991 to June 1994, 150 patients underwent aortic valve replacement with the O'Brien-Angell stentless porcine xenograft (Bravo Cardiovascular Model 300, Cryolife, Atlanta, GA). To establish trends we analyzed three consecutive groups of 50 patients. We found significant differences in low postoperative gradients (mean < or = 10 mm Hg): 24% in group 1, 42% in group 2, and 96% in group 3. Comparing groups 1 and 3, gradients were significantly lower in all valve sizes. The difference is credited to better supraannular positioning of the valve, which is the key to the learning curve. Trivial central regurgitation was present in the three groups at 6%, 12%, and 0%, respectively. Peripheral regurgitation was trivial in 6%, 8%, and 0%, and mild to moderate in 4%, 2% and 0%, respectively. Seventy-eight of 107 patients with an available follow-up exceeding 1 year had noninvasive controls. Two early cases with moderate perivalvular leaks evolved to moderately severe leaks. Two valves were explanted. The O'Brien-Angell stentless valve is easy to handle and correct supraannular positioning provides excellent hemodynamic results.

Adult↗
PubMed1995

Pulmonary time-of-flight MR angiography at 1.0 T: comparison between 2D and 3D tone acquisitions.

The purpose of this study was to compare the performance of 2D vs. 3D time-of-flight (TOF) methods in imaging the normal pulmonary arteries with commercially available 1.0 T equipment. The study was conducted in 20 volunteers and 7 patients with suspected pulmonary embolism (PE). To reduce artifacts caused by cardiac and respiratory motion, MR images were acquired in volunteers using two-dimensional (2D), gradient-recalled echo (GRE), breath-hold techniques, and three-dimensional (3D) acquisitions. Sagittal thin (6-MM) segmented k-space 2D sections obtained with cardiac gating during systole (turboFLASH, TR/TE9/6 ms, 14 segments of 9 lines) and incremented flip-angles (TONE), and 50-mm 3D volume TONE acquisitions with 32 partitions (FISP, TR/TE34/10ms) were successively performed. In the second phase of the study, patients were examined only with the 3D technique. Images of volunteers were qualitatively and quantitatively analyzed. S/N ratios were statistically compared by means of the paired-sample Wilcoxon ranked-signed test, a value of p < .05 being significant. In volunteers, 3D acquisitions displayed significantly more segment-order pulmonary arteries on average than did 2d acquisitions displayed significantly more segment-order pulmonary arteries on average than did 2D acquisitions (2.95 +/- 0.64 vs. 2.2 +/- 0.85, respectively; p < .01). Moreover, the signal intensity of arteries within the lungs was less homogeneous in the 2D than in the 3D technique, with a signal intensity ratio between peripheral and proximal arteries of 63% +/- 7% and 73% +/- 2%, respectively (p < .05). In patients, no erroneous diagnoses were obtained using the 3D technique. 3D images of normal lungs provide MR angiograms of better quality than do 2D images, and require less contribution from subjects because they are performed in free breathing. Ongoing improvements in MR sequences and further studies are now necessary to assess the value of 3D TONE MRA in the diagnosis of PE.

Adult↗
PubMed1995

Thoracic aortic dissection: diagnosis with transesophageal echocardiography versus MR imaging.

PURPOSE: To compare transesophageal echocardiography (TEE) and magnetic resonance (MR) imaging in the diagnosis of dissection of the thoracic aorta. MATERIALS AND METHODS: Thirty-one consecutive patients with clinically suspected aortic dissection and 10 postoperative patients underwent transesophageal color Doppler echocardiography and MR imaging. Imaging results were compared at independent double-blind readings. Final diagnosis was obtained from consensual review of all corroborative studies. RESULTS: MR imaging depicted the intimal flap in 95% of aortic dissections; TEE, in 86% (P < .05). In surgical patients, the sensitivity of MR in detection of residual dissection was 100% versus 86% with TEE (P < .05). The inferior extent of the dissected lumen was seen only with MR imaging. False-positive results occurred in two cases with TEE and in one with MR imaging. CONCLUSION: MR imaging is superior to TEE in the evaluation and follow-up of dissection of the thoracic aorta. Because the availability of MR is limited, however, TEE should remain the standard modality for diagnosis.

Adult↗
PubMed1994

Nonsynchronous changes in myocardial collagen mRNA and protein during aging: effect of DOCA-salt hypertension.

Myocardial fibrosis has been investigated in 3-, 16-, and 24-mo-old normal rats and also in 24-mo-old rats subjected to deoxycorticosterone acetate (DOCA)-salt treatment-induced-hypertension. Collagen content was assessed both histologically and by hydroxyproline assay. Type I and III procollagen mRNA levels were quantitated by Slot Blot analyses. Aging is associated with fibrosis as shown both biochemically (hydroxyproline concentration in 3-, 16-, and 24-mo-old rats was 0.70 +/- 0.05, 0.92 +/- 0.07, and 1.57 +/- 0.13 mg/g of left ventricle, respectively, P < 0.05 and P < 0.0001 vs. 3 mo) and histologically. By contrast, type I procollagen mRNA levels decreased during aging (from -63%, P < 0.001 in 16-mo-old rats and -51%, P < 0.01 in 24-mo-old rats vs. 3-mo-old rats) as well as type III procollagen mRNA levels. DOCA-salt treatment in 24-mo-old rats had no effect on either the degree of fibrosis or the mRNA levels. We conclude that nonsynchronous changes in myocardial collagen mRNA and protein occur during aging, indicating translational and/or posttranslational mechanisms in collagen regulation. Hypertension during senescence did not modify collagen deposition at either the protein or mRNA levels.

Aging↗
PubMed1993

Normal and hypertrophied senescent rat heart: mechanical and molecular characteristics.

The energetics of the senescent (S) rat heart and the mechanisms by which it adapts to pressure overload have been investigated by simultaneous cardiac mechanical, energetic, and molecular biological studies. Compared with young adult (YA), S papillary muscles had an improved economy of contraction since the curvature (G) of Hill's (Proc. R. Soc. Lond. B. Biol. Sci. 126:136-195, 1938) hyperbola was increased (S, 1.93 +/- 0.13; YA, 1.60 +/- 0.07, P < 0.05). In addition, the maximum unloaded shortening (Vmax) and relengthening velocities were both reduced in S. In parallel, both alpha-myosin heavy chain (MHC) and sarcoplasmic reticulum (SR) Ca(2+)-adenosinetriphosphatase (ATPase) mRNA contents were reduced (-30 and -28%, respectively), whereas beta-MHC mRNA was increased (+91%). The active tension (S, 40.0 +/- 2.6; YA, 50.1 +/- 2.5 mN/mm2, P < 0.01) was depressed although the active force remained unchanged (S, 52.0 +/- 4.0; YA, 47.5 +/- 2.5 mN). Pressure overload in senescent deoxycorticosterone acetate (DOCA)-salt rats induced a left ventricular hypertrophy (+43%) and a further decrease in both Vmax (S, 2.81 +/- 0.10; DOCA-salt, 2.55 +/- 0.13 initial length corresponding to peak of length-active curve/s, P < 0.05) and alpha-MHC mRNA (-30%) content. Senescence modifies mechanics and gene expression in a way similar to pressure overload. During senescence, an additional overload induces left ventricular hypertrophy and attenuates Vmax without worsening the economy of the contraction.

Aging↗
PubMed1993

[Cardiac metastasis disclosed by ventricular tachycardia. Diagnosis by echocardiography and ultrafast tomodensitometry].

The authors report the case of a right ventricular metastasis presenting with ventricular tachycardia and underline the usual diagnostic problems of secondary cardiac tumours, the symptoms of which are often unspecific and late. The appearance of a cardiac arrhythmia in the absence of known cardiac disease should raise the possibility of a cardiac metastasis in patients with malignant disease. The reported case also illustrates the diagnostic value of non-invasive cardiac imaging techniques (echocardiography and ultra-fast computerised tomography) in this context.

Aged↗