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Biomedical subjects

C Acar

Publications and source records attributed to C Acar.

At least 127 records · Page 7Linked to original sources
PubMed1989

[Use of 2 internal mammary arteries in coronary bypass. Combination with a bypass using the gastroepiploic artery in 2 cases].

Coronary revascularisation by bilateral internal mammary artery grafting was performed in 39 patients. The left internal mammary was anastomosed to the left anterior descending (N = 22), the left lateral (N = 12) or diagonal artery (N = 5). The right internal mammary was implanted on the right coronary (N = 17), the left anterior descending (N = 16), the left lateral (N = 3) or diagonal artery (N = 3). In two cases, the inferior myocardial segments were revascularised by grafting the gastroepiploic artery. Three patients died and one patient had signs of postoperative myocardial infarction. Respiratory complications, usually mild, occurred in 5 patients. Bilateral internal mammary artery grafting should be reserved for: 1) young patients, 2) those without usable leg veins (varicose veins, previous stripping or coronary bypass surgery). The gastroepiploic artery is a useful arterial graft for revascularizing regions of the heart inaccessible to the internal mammary arteries.

Adult↗
PubMed1989

[Postoperative iatrogenic coronaro-ventricular fistula].

Acquired coronary cardiac fistulas are rare. To date, thirty cases have been published in the literature, all secondary to thoracic trauma. The right cardiac chambers were more frequently involved. A recent continuous cardiac murmur is the most constant finding. Nontreated, these lesions tend to induce coronary insufficiency and congestive heart failure. 22 of the 30 reported cases were managed surgically. We hereby report a case of postoperative coronary cardiac fistula secondary to left ventricular venting, in which the fistula involved the left ventricular cavity.

Aortic Valve↗
PubMed1989

Studies on prolonged acute regional ischemia. I. Evidence for preserved cellular viability after 6 hours of coronary occlusion.

Six hours of coronary occlusion has been thought to produce extensive and irreversible transmural damage and no possibility of salvage by reperfusion. This has been based on findings of adenosine triphosphate depletion and histochemical (triphenyltetrazolium chloride nonstaining) and ultrastructural changes (conventional preparatory techniques). This study tests the hypothesis that, in contrast to conventional wisdom, considerable structural and mitochondrial functional integrity remains in cardiac muscle subjected to 6 hours of regional ischemia. Twenty open-chest anesthetized dogs underwent isolation of the left anterior descending coronary artery and were observed for 6 hours. Eight of the 20 did not undergo ischemia and served as controls. Twelve underwent 6 hours of proximal ligation of the left anterior descending coronary artery (30% +/- 2% area at risk). Transmural biopsy specimens were analyzed. Coronary occlusion reduced regional blood flow (radioactive microspheres) to less than 10 ml/100 gm/min (p less than 0.05) and dyskinesia persisted in the area at risk for 6 hours. High-energy phosphates (adenosine triphosphate and creatine phosphate) declined to negligible levels and histochemical damage occurred (49% +/- 12% triphenyltetrazolium chloride non-staining). Mitochondrial ultrastructural changes (low protein denaturation embedding technique) were mild (the integrity of the inner and outer mitochondrial surface membranes and crystal membranes was maintained and myofibrillar degeneration did not occur). Mitochondrial oxidative phosphorylation rate remained at 63% of control levels, respiratory control index remained at 77%, and adenosine diphosphate/oxygen ratio was maintained at 96%. Mitochondrial Ca++ increased with lanthanum (from 26 to 46 nmol/mg protein, p less than 0.05), but irreversible calcium precipitation did not occur; calcium could be mobilized to normal levels (i.e., 13 nmol/mg protein) by ethylenediaminetetraacetic acid chelation. These data support our inference that necrosis does not occur after 6 hours of coronary occlusion and suggest that muscle salvage by reperfusion is possible after at least 6 hours of regional myocardial ischemia.

Adenosine Triphosphate↗
PubMed1989

Studies on prolonged acute regional ischemia. II. Implications of progression from dyskinesia to akinesia in the ischemic segment.

This study analyzed the pattern of regional wall motion in 58 dogs undergoing 4 to 6 hours of left anterior descending coronary artery occlusion. Regional wall motion was measured by ultrasonic crystals and ischemic muscle either remained dyskinetic (-40% of control systolic shortening, n = 26) or progressed toward akinesia (less than 20% of control systolic shortening or greater than 50% reduction in passive lengthening, n = 32). Ten dogs underwent unmodified blood reperfusion. Regional blood flow (radioactive microspheres), histochemical damage (triphenyltetrazolium chloride staining), and mitochondrial function were determined. Hearts showing persistent dyskinesia had more collateral flow (12 versus 2 ml/100 gm/min, p less than 0.05), less histochemical damage (26% versus 63% area at risk/area of nonstaining, p less than 0.05), and better retention of mitochondrial oxidative phosphorylation capacity (adenosine triphosphate, 622 versus 444 nmol/mg protein/min, p less than 0.05), and tended toward mitochondrial calcium accumulation (48 versus 64 nmol/mg protein). Unmodified blood reperfusion after 4 hours of ischemia produced prompt akinesia (-2% +/- 3% systolic shortening) and was associated with increased edema (82% water content), caused the low-reflow phenomenon (19% control subendocardial flow, 13 ml/100 gm/min), and increased histochemical damage (69% triphenyltetrazolium chloride nonstaining, p less than 0.05). These findings suggest that persistent dyskinesia during early ischemia (first 6 hours) may reflect a relatively optimistic sign, as regression to akinesia occurs in muscle with less collateral flow, more impaired mitochondrial function, worsened calcium homeostasis, and more severe histochemical and ultrastructural damage. These observations imply that careful evaluation of ischemic wall motion may provide a valuable insight into potential muscle salvage.

Adenosine Triphosphate↗
PubMed1989

Studies on prolonged acute regional ischemia. III. Early natural history of simulated single and multivessel disease with emphasis on remote myocardium.

The early natural history of left anterior descending coronary artery occlusion was studied in 35 open-chest anesthetized dogs observed for 6 hours. Six control dogs underwent isolation of the left anterior descending without occlusion, 13 underwent isolated occlusion of the artery to simulate single-vessel disease, and 14 underwent occlusion of the left anterior descending and 50% stenosis of the circumflex coronary artery to simulate multivessel disease. Regional systolic shortening was measured by ultrasonic crystals. Control dogs had a mild fall in cardiac output (27%) and rise in aortic pressure (15 mm Hg). Ischemia produced immediate dyskinesia (-60% of control systolic shortening), and passive lengthening persisted for 6 hours. All dogs with only occlusion of the left anterior descending artery survived (0% mortality). They were less prone to ventricular fibrillation (46% versus 79%, p less than 0.05), developed compensatory hypercontractility of remote muscle (131% of control systolic shortening, p less than 0.05), mild energy and substrate depletion, and anaerobic metabolism (increased glucose-6-phosphate, p less than 0.05) despite maintenance of "normal" blood flow. In contrast, the early mortality rate was 57% (p less than 0.05) when 50% circumflex stenosis coexisted. Intractable ventricular fibrillation and/or cardiogenic shock caused the deaths. Remote muscle became progressively hypocontractile (61% of control systolic shortening, p less than 0.05), with progressive reduction in stroke work index (less than 0.5 gm-m/kg, p less than 0.05). Remote muscle showed moderate substrate and energy depletion (greater than 60% fall of adenosine triphosphate and creatine phosphate, 37% fall of glutamate) and more pronounced evidence of anaerobic metabolism (glucose-6-phosphate rose greater than 400%, p less than 0.05) despite normal blood flow. Mitochondrial ultrastructure and function remained intact in all hearts. These findings suggest that remote muscle is the principal determinant of mortality after an otherwise nonlethal ischemic event. Functional deterioration despite normal blood flow to remote muscle suggests either autoregulatory failure or substrate depletion as a cause of hypocontractility. The structural and functional integrity of mitochondria in ischemic and remote myocardium implies that salvage is possible despite hemodynamic deterioration and intractable ventricular fibrillation.

Adenosine Triphosphate↗
PubMed1989

Studies on prolonged acute regional ischemia. IV. Aggressive surgical treatment for intractable ventricular fibrillation after acute myocardial infarction.

Of 21 dogs undergoing ligation of the left anterior descending coronary artery and 50% stenosis of the left circumflex coronary artery, 15 developed intractable ventricular fibrillation and underwent 1 added hour of femoro-femoral bypass. Three hearts were removed after 1 hour on bypass without myocardial reperfusion for biochemical and mitochondrial analysis. After the 1 hour, five underwent unmodified blood reperfusion on bypass; seven underwent 1 hour of aortic clamping on vented bypass to simulate coronary artery bypass grafting with multidose blood cardioplegic reperfusion. Regional systolic shortening was measured with ultrasonic crystals and cardiac output was measured by thermodilution techniques. All six hearts with no ventricular fibrillation or with reversible ventricular fibrillation and hearts that were not reperfused developed cardiogenic shock (40% decrease in stroke work index, p less than 0.05) because of persistent left ventricular dyskinesia (-40% of systolic shortening, p less than 0.05) and progressive circumflex hypocontractility (48% systolic shortening, p less than 0.05) and showed extensive (68%) triphenyltetrazolium chloride nonstaining. Two dogs died of left ventricular power failure (33% mortality rate). In contrast, 11 of 12 dogs that were reperfused could be weaned from bypass (8% mortality rate). The four dogs surviving after unmodified blood reperfusion (20% mortality rate) showed severe residual left ventricular dysfunction (39% of control stroke work index, p less than 0.05), had equivocal recovery of anterior contractility (10% +/- 7% of systolic shortening), had marginal recovery of contractility in the remote myocardium (60% +/- 11% of systolic shortening), and had extensive triphenyltetrazolium chloride nonstaining (58%). Conversely, all seven dogs with intractable ventricular fibrillation undergoing controlled reperfusion after 4 hours of ischemia recovered normal stroke work index (91%), regained 23% of systolic shortening in the region supplied by the left anterior descending coronary artery (p less than 0.05), 125% of systolic shortening in the circumflex region (p less than 0.05), and showed only 25% triphenyltetrazolium chloride nonstaining (p less than 0.05). These results suggest aggressive treatment of intractable ventricular fibrillation after acute myocardial infarction by providing reperfusion on bypass can salvage hearts thought previously to be damaged irreversibly.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1989

Studies of retrograde cardioplegia. I. Capillary blood flow distribution to myocardium supplied by open and occluded arteries.

This study defines the nutritive (i.e., capillary) distribution of blood cardioplegic solutions delivered via retrograde and antegrade techniques to muscle supplied by open and occluded coronary arteries where myocardial segments are in jeopardy of inadequate cardioplegic protection. Open-chest anesthetized dogs were studied by mixing radioactive microspheres (15 +/- 5 microns) with a blood cardioplegic solution and administering cardioplegia either into the coronary sinus or into the proximal aorta with the left anterior descending coronary artery open or occluded (30% +/- 2% area at risk). Nutritive flow (i.e., percentage of delivered 15 microns microspheres trapped in myocardial capillaries) during retrograde infusions averaged 65% versus 87% with antegrade cardioplegia (p less than 0.05). Retrograde and antegrade cardioplegic nutritive flow to all left ventricular regions was comparable with the left anterior descending coronary artery open (65 versus 82 ml/100 gm/min, p greater than 0.05), and both methods provided preferential hyperperfusion of subendocardial muscle (endocardial/epicardial ratios 1.6 and 1.5, respectively). Nutritive flow to muscle supplied by the occluded left anterior descending coronary artery was preserved better by retrograde than antegrade cardioplegia (35 versus 5 ml/100 gm/min, p less than 0.05). Preferential subendocardial hyperperfusion was maintained during retrograde cardioplegia (52 ml/100 gm/min, endocardial/epicardial ratio 1.6), but flow was redistributed away from subendocardial muscle with antegrade cardioplegia (less than 2 ml/100 gm/min, endocardial/epicardial, 0.29, p less than 0.05). Left ventricular flow was reduced markedly during retrograde infusion with the left anterior descending coronary artery open or occluded (23 and 12 ml/100 gm/min), but septal cooling was superior to antegrade cardioplegia (15 degrees +/- 1 degree C versus 20% +/- 3%, p less than 0.05) despite near-normal antegrade septal flow (the left anterior descending coronary artery was ligated beyond the first septal branch). Right ventricular nutritive flow was only 7 ml/100 gm/min during retrograde coronary sinus perfusion and was maintained normally with antegrade cardioplegia.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1989

Studies of retrograde cardioplegia. II. Advantages of antegrade/retrograde cardioplegia to optimize distribution in jeopardized myocardium.

This study tests the hypothesis that retrograde/antegrade cardioplegic delivery can overcome the limitations of poor cardioplegic distribution resulting from either technique alone and, potentially, may expand the safety of using internal mammary artery grafts in cardiac muscle in jeopardy of inadequate cardioplegic protection. Jeopardized myocardium was produced in 20 dogs by ligating the left anterior descending coronary artery for 15 minutes before starting cardiopulmonary bypass and by 1 hour of aortic clamping with multidose 6 degrees C cold blood cardioplegia. Five dogs received antegrade cardioplegia via the aortic root. Ten dogs received retrograde cardioplegia via the coronary sinus. Five additional dogs received retrograde/antegrade cardioplegia via both routes. The ligature on the left anterior descending coronary artery was removed after aortic unclamping, and regional myocardial temperature (thermistor probe), segmental shortening (ultrasonic crystals), and global left ventricular and right ventricular myocardial function were evaluated. Antegrade cardioplegia produced excellent right ventricular cooling (14 degrees C) and allowed complete right ventricular functional recovery. However, it failed to cool muscle supplied by the left anterior descending coronary artery (only 31 degrees versus 12 degrees C, p less than 0.05), postischemic global left ventricular function recovered only 38% (p less than 0.05), and segmental shortening in the region supplied by the left anterior descending coronary artery recovered only 22% (p less than 0.05). Retrograde cardioplegia produced homogeneous cooling (17 degrees C) and allowed near normal recovery of global and regional left ventricular function (99% and 86%), but right ventricular cooling was variable (19 degrees to 30 degrees C) and right ventricular function recovered inconstantly (range 64% to 100%, average 82%). The best myocardial protection occurred after retrograde/antegrade cardioplegia; myocardial cooling was homogeneous, left ventricular and right ventricular global function recovered completely (95% and 90%), and regional contractility in muscle supplied by the left anterior descending coronary artery returned to 84% of control. We conclude that retrograde/antegrade cardioplegia provides better myocardial protection than either technique alone, ensures good cardioplegic distribution to the left and right ventricles, and allows regional delivery of cardioplegic flow to segments supplied by occluded arteries.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1988

[Histochemical quantification of muscular ischemia: effect of treatment with naftidrofuryl].

Evaluation of degree of muscle ischemia of a limb and its reversibility is a poorly resolved practical problem, and it has not been clarified whether vasodilatory and circulatory spasmolytic substances possess, in addition to an effect of increasing irrigation, any direct action on muscle cell energy metabolism. An experimental study used histochemical techniques to evaluate oxidative enzyme activity of tissues. The compound tetrazolium nitro-blue (NBT), when reduced by tissue dehydrogenases, has the property of producing a dense non-crystalline blue pigment designated "formazan". During muscle ischemia, the time of appearance of this reaction increases with degree of ischemia through the bias of the decrease or disappearance of succinate-dehydrogenases. Transient ischemia of hindpaw, over 3, 6, 9, 12, 15 and 18 hours, was provoked by tourniquet in 49 rats treated with a vasodilator (naftidrofuryl) and 21 untreated (control) rats. Spontaneous revascularization occurred after removal of the tourniquet. Muscles were studied by microsurgical removal of specimens on removal of tourniquet and 1 and 12 hours and 3, 7 and 14 days after its removal (fig. 1 and 2). Times for staining of muscles with tetrazolium were measured and curves of comparative times established (fig. 3 and 4). Histopathologic specimens were also obtained at the same periods (fig. 5, 6, 7). Results of histochemical studies with tetrazolium and with quantitative determination of degree of cellular anoxia showed the action of naftidrofuryl to be related to mitochondrial metabolism of skeletal muscle, specifically for succinate-dehydrogenase. Clinical application in the determination of therapy and of functional prognosis of an ischemic limb is a possibility by the use of the NBT test in vascular surgery.

Animals↗
PubMed1986

[Coronary endarterectomy associated with by-pass. A series of 111 patients controlled angiographically].

Out of 2 638 patients undergoing coronary bypass surgery at the Arnault Tzanck Centre from 1973 to September 1984, 305 (12%) also required coronary endarterectomy. One hundred and eleven of these patients had control angiographies at the Centre and were the object of this study. Endarterectomy was carried out on a totally occluded artery in 38% of cases and was performed out of necessity in the other cases. One hundred and twenty-nine disobliterations were performed in these 111 patients. The average number of bypass grafts per patient was 2.8. The overall hospital mortality was 6% (19 out of 305) which was higher than for bypass surgery alone. The postoperative myocardial infarction rate was 10%. The 117 control angiographies were performed on average during the 8th month after surgery; these controls were routine in 99 cases (84.5%) in Stage I of the NYHA classification and for recurrent angina in 18 cases (15.5%). The endarterectomised vessel was patent in 72% of cases, which was less than the patency rate of the bypass grafts. Considering the indications of necessity, this result is satisfactory and is compared which those of other reported series.

Adult↗
PubMed1986

Reperfusate composition: benefits of marked hypocalcemia and diltiazem on regional recovery.

This study tests the hypothesis that improved muscle salvage is possible by markedly reducing the ionic calcium (Ca++) of the reperfusate (less than 250 mumol/L) and adding a calcium channel-blocking drug (diltiazem). Preliminary pilot studies showed that a 20-minute infusion of markedly hypocalcemic substrate-enriched blood cardioplegic solution (less than 250 mumol/L Ca++) did not affect left ventricular function adversely and that a 150 to 250 mumol/L substrate-enriched blood cardioplegic solution, delivered during total vented bypass with diltiazem, 300 micrograms/kg body weight, produced the most consistent functional recovery and the least histochemical evidence of damage (triphenyltetrazolium chloride nonstaining) after 2 hours of regional ischemia. Experimental studies of 2 hours of regional ischemia were followed by either regional normocalcemic (1000 to 1200 mumol/L) blood cardioplegic reperfusion in bypassed hearts, with or without diltiazem, or hypocalcemic (150 to 150 mumol/L) blood cardioplegic reperfusion with diltiazem for 20 minutes. Results showed that hypocalcemic blood cardioplegic solution with diltiazem produced superior recovery of systolic shortening (58% versus 11% systolic shortening, p less than 0.05) and limitation of histochemical damage (11% versus 54%, p less than 0.05), in comparison with normocalcemic blood cardioplegic solution without diltiazem. These studies suggest that modifying the regional reperfusate by markedly reducing ionic calcium levels and adding calcium channel-blocking drugs is safe and may improve myocardial salvage more than using substrate-enriched blood cardioplegic solution alone.

Animals↗
PubMedDate not supplied

Chronic hemolytic anemia associated with glucose 6-phosphate dehydrogenase (Guadalajara)1 159 C --> T (387 Arg --> Cys) deficiency associated with Gilbert syndrome in a Turkish patient.

The case of an 8-year-old male child with severe kernicterus sequelae is presented in this paper. The child's hemoglobin value varied between 6.0 and 10.8 g/dL and his reticulocyte count ranged between 3.4 and 46.0% during the steady-state condition and hyperhemolytic crisis, respectively. A chronic hemolytic type of red cell G6PD deficiency was diagnosed. DNA studies indicate that the mutation was G6PD Guadalajara 1159 C --> T (387 Arg --> Cys) that is situated at the NADP binding site. Additionally, extra nucleotides of (TA) in the A(TA)n TAA motif of the promoter region of the uridine diphosphate-glucuronosyltransferase gene (UGT-1 A) were found to be homozygous in the patient. The coexistence of Gilbert syndrome with a chronic type of G6PD deficiency was suggested as a cause of neonatal hyperbilirubinemia leading to kernicterus.

Anemia, Hemolytic↗
PubMedDate not supplied

Noninvasive measurement of medium-sized artery intima-media thickness in humans: in vitro validation.

Recent research in ultrasound technology has led to the development of a high-resolution echo-tracking device. The present study was performed to evaluate the accuracy in the measurement of human radial artery intima-media thickness with this new device. We determined the correlation between histological and ultrasonic measurements of intima-media thickness in 15 radial artery segments obtained from the distal end of the wrist-elbow harvest for coronary bypass grafting in patients with coronary heart disease. For arterial intima-media thickness, a positive correlation was observed between ultrasonic and histological measurements (r = 0.618; p < 0.014), and the difference between ultrasound and histology measurements was 41 +/- 66 microns, with the higher measurements found by the ultrasonic device. In a subgroup of 11 patients, we determined the correlation between in vivo ultrasonic measurements of radial artery intima-media thickness at the preoperative stage and in vitro ultrasonic measurements of intima-media thickness obtained postoperatively in the same arterial segments. Internal diameter was larger in vivo than in vitro, and intima-media thickness was smaller in vivo than in vitro. The cross-sectional area of the arterial wall was calculated from internal diameter and intima-media thickness. In vitro wall cross-sectional area was correlated with in vivo wall cross-sectional area (r = 0.929; p < 0.0001). Repeatability of in vivo intima-media thickness measurements was investigated in 10 subjects through the calculation of the repeatability coefficient as defined by the British Standards Institution.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation Studies as Topic↗
PubMedDate not supplied

[Circulatory assistance through cardiomyoplasty and aortomyoplasty. Experience and first clinical results].

The finding that skeletal muscles can be made resistant to fatigue by progressive electrical stimulation has been used as a means of providing circulatory support in cardiac surgery. The first application of this discovery was dynamic cardiomyoplasty, performed for the first time in man in 1985 at the Broussais Hospital, Paris. The latissimus dorsi muscle is transposed into the thorax, then attached around the heart and finally stimulated synchronously with the ventricular systole. So far, more than 200 patients in the whole world (including 57 at the Broussais Hospital) have undergone this operation with results that are increasingly encouraging. In these cases the muscle is used to reinforce or replace the left or right ventricle, but other applications are being studied, such as double cardiomyoplasty (left latissimus dorsi and right pectoralis major muscles), cardiomyoplasty of the right atrium and aortomyoplasty which produces aortic counterpulsation. The development of these techniques underlines the ever growing interest raised by this type of autologous circulatory support.

Assisted Circulation↗
PubMedDate not supplied

[Changes in the vascular wall induced by surgical glues. Experimental study].

The effects on vascular tissues of two different types of surgical glue, gelatin-resorcinol-formaldehyde (GRF) and fibrin (Tissucol) were tested on the rat abdominal aorta. The GRF glue induced destruction of the vascular wall: multiple inclusions of the glue were noted in the media. Conversely, the fibrin glue preserved the normal architecture of the three arterial layers. The use of GRF glue therefore should be avoided on particularly fragile tissues (e.g. coronary arteries), and it seems preferable in such cases to use the fibrin glue.

Animals↗