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Biomedical subjects

Y Hasin

Publications and source records attributed to Y Hasin.

At least 55 records · Page 3Linked to original sources
PubMed1995

Retrieval of occluding unexpanded Palmaz-Schatz stent from a saphenous aorto-coronary vein graft.

The Palmaz-Schatz coronary stent is used frequently to reduce the rate of restenosis of balloon angioplasty in saphenous vein grafts. In many European centers, the stent, manually crimped on a balloon, is advanced across the stenosis without a protective sheath. This report describes a patient in whom an attempt to deploy a stent in the orifice of a saphenous vein graft was complicated by dislodgement of the unexpanded stent from the balloon. The unexpanded stent caused immediate occlusion of the vein graft and severe ischemic symptoms. The stent was retrieved by inflation of another balloon in the graft, distal to the stent, pulling the balloon toward the guiding catheter, and then withdrawing the whole system.

Aged↗
PubMed1995

The effect of cytotoxic lymphocytes on contraction, action potential and calcium handling in cultured myocardial cells.

Cytotoxic T lymphocytes are important in the pathogenesis of several disease states, yet the pathophysiology of the lymphocyte-myocyte interaction is not well known. We have developed in vitro viral and autoimmune models to study the physiological phenomena associated with this interaction. To produce these models, lymphocytes were obtained from adult rats injected either with mengo virus or autologous cardiac myocytes. Cardiac myocytes from neonatal rats were then exposed to these lymphocytes. In both models, reversible physiologic changes in myocytes preceded irreversible cell damage. The physiologic changes included reduced amplitude of myocyte contraction, impairment of relaxation and prolongation of the duration of contraction and action potential. In addition, oscillations were noted in the plateau phase of the action potentials. These physiologic changes were accompanied by an early elevation in the cytosolic free calcium concentration, a late elevation in the total exchangeable calcium pool, and attenuation of the [Ca2+]i transient signals. Verapamil inhibited the late elevation in the total exchangeable calcium pool, but failed to inhibit the early elevation in the cytosolic free calcium concentration. These phenomena may explain transient cardiac functional abnormalities that may appear during myocarditis prior to cell destruction.

Action Potentials↗
PubMed1995

Early intravenous thrombolysis in acute myocardial infarction: the Jerusalem experience.

Myocardial damage in acute myocardial infarction is a time-dependent process. We examined the influence of very early thrombolytic therapy, comparing prehospital to hospital administration, in a consecutive group of patients with myocardial infarction on mortality, complications and the preservation of left ventricular function. Seven hundred sixty patients received early thrombolytic therapy: 114 at home (time delay to treatment 1.4 +/- 0.8 h) and 646 in hospital (2.1 +/- 1.0 h). Sixteen patients died in hospital and significant hemorrhage occurred in 15 (including three patients with hemorrhagic stroke). There was no difference between groups in hospital mortality or rate of complications. The duration of ischemia was shorter in patients with prehospital therapy (pain duration: 3.3 +/- 2.1 vs. 4.0 +/- 2.2; P < 0.05, and time to recovery of the ST segment in the electrocardiogram: 4.3 +/- 3.3 vs. 6.6 +/- 6.3; P < 0.002). Peak plasma creatine kinase was earlier in patients with prehospital therapy (11.2 +/- 5.0 vs. 13.0 +/- 5.8; P < 0.002), although there was no difference between groups in the absolute peak plasma level. Left ventricular function was assessed by contrast ventriculography 1 week after admission (616 patients). Ventricular function was better in patients with prehospital therapy: (ejection fraction of 58 +/- 13% vs. 54 +/- 15%; P < 0.05 and a left ventricular dysfunction index of 534 +/- 515 vs. 691 +/- 519 units; P < 0.05). We conclude that prehospital thrombolytic therapy is feasible and safe. Reperfusion is achieved earlier and more myocardium can be salvaged using this strategy without increasing the rate of complications.

Coronary Angiography↗
PubMed1995

Aorto-atrial fistula following internal jugular vein catheterization.

A 48-year-old woman with giant haemangioma of the liver underwent percutaneous transjugular placement of a stent in the left hepatic vein for relief of an obstruction due to the compression of the benign liver tumour. Following the procedure, paroxysmal atrial fibrillation occurred and right-sided heart failure gradually appeared. Echocardiography and cardiac catheterization demonstrated a fistula between the aortic root and the right atrium, that was confirmed on surgery.

Aortic Diseases↗
PubMed1995

Combined mechanical and thrombolytic treatment for totally occluded bypass grafts.

Totally occluded venous grafts are usually less amenable to mechanical reperfusion alone (for example percutaneous transluminal coronary angioplasty, PTCA) because of the large mass of thrombotic material within the graft. A combined approach using mechanical and thrombolytic treatment might therefore be more successful. Twenty one patients (20 males, one female) with a mean age of 64.5 (SD 5.6) years underwent angiography because of crescendo or unstable angina (n = 19) or myocardial infarction (n = 2) at a mean of 21.7 (18.6) days after onset of symptoms (range 1-60). All patients had had coronary artery bypass grafting (CABG) at a mean of 8.02 (4.02) years (range 0.3-13 years) before the current admission. At catheterisation, totally occluded venous bypass grafts to the left anterior descending coronary artery or diagonal (n = 10), marginal (n = 6), or right coronary artery (n = 5) were found. A combination of PTCA and thrombolytic treatment (in eight patients extended thrombolysis for 24 hours) was successful in reopening the venous graft in 16/21 patients (76.2%). Immediate complications included femoral haematoma (4), distal embolisation (3), and infection in one patient. Out of 13 patients catheterised within three months, two had reoccluded, seven had restenosis, while four had patent grafts. Recurrent PTCA (at least once more) was done in eight patients. At long term follow up of a mean of 26.7 (21.6) months (range 4-75 months), four patients were asymptomatic, eight still suffered from mild stable angina, while three had recurrent hospital admissions and needed a second coronary artery bypass. A combination of thrombolytic treatment and PTCA is a feasible and practised approach to recanalise recently occluded venous bypass grafts.

Aged↗
PubMed1995

[Angioplasty for vein grafts and native coronary arteries after previous coronary artery bypass grafting].

219 patients after previous coronary artery bypass grafting (CABG) underwent coronary artery or vein graft angioplasty in 1984-1991. 452 stenotic lesions out of 498 were successfully dilated in 337 procedures (90.7%). For arterial lesions the initial success rate had been 89.2% (321/360) and for vein graft lesions 94.9% (131/138). For repeated angioplasty the success rate was the same. Major complications included 3 deaths (0.9%). 15 myocardial infarctions (5.3%) and 1 emergency CABG. Factors that had reduced the success rate were lesions at the proximal anastomosis, total occlusions, and complex (type C) lesions. Time since grafting did not affect success rate of the second procedure. Restenosis after successful angioplasty was 37.3% (34/91) for arterial lesions and 56.8% (25/44) for graft lesions, after a mean time of 11.2 +/- 2.7 months. Restenosis was more common in type C lesions and old vein grafts. There was considerable improvement in treadmill exercise time of patients after the angioplasty (5.92 vs 7.31 minutes) and in double product. During a follow up of about 3 years, 7.6% (15/196) died of cardiac events, 5.2% (10/189) had myocardial infarctions, 10.5% (20/189) were reoperated and 31.0% (68/219) needed at least 1 repeat angioplasty. Long term followup was better after angioplasty of native arteries than of grafts. After angioplasty of vein grafts, there were more cardiac related deaths, more MIs and more reoperations than after angioplasty of native arteries: 11.5% vs 3.5%, 9.6% vs 2.8%, 21% vs 4.9%, respectively, than in the arterial group. Considering the high mortality and morbidity of reoperation, balloon angioplasty in selected patients may be the preferred strategy. Clinical and angiographic results are better after re-angioplasty of native arteries than vein grafts.

Angioplasty, Balloon, Coronary↗
PubMed1994

Physiological changes induced in cardiac myocytes by cytotoxic lymphocytes: an autoimmune model.

BACKGROUND: cytotoxic lymphocytes are important in the pathogenesis of several disease states, yet, the pathophysiology of lymphocyte-myocyte interaction is not well known. METHODS AND RESULTS: We have developed a model for the in vitro evaluation of autoimmune cytotoxic myocardial damage. Cardiac myocytes were repeatedly injected to adult autologous rats. Following 3 months, histological evidence of myocarditis was seen in 20% of the hearts. Cultured myocytes obtained from newborn rats were exposed to lymphocytes isolated from the immunized animals. Cytotoxic activity was measured using crystal violet staining test. The percentage of killing was increased as the ratio of lymphocytes/myocytes was increased. Verapamil did not block this cytotoxic effect. No killing was seen when myocytes were exposed to non-sensitized lymphocytes. Physiological changes induced in myocytes by cytotoxic lymphocytes were studied. Cell wall motion was measured by an optical method and action potentials with intracellular microelectrodes. Physiological changes observed in myocytes following exposure to cytotoxic lymphocytes included: Impaired relaxation with prolonged contractions, oscillations and prolongation of the plateau of the action potential. Cellular contraction was prolonged up to 4 s before total arrest of spontaneous activity. Verapamil but not tetrodotoxin restored action potentials and contractions to normal. Supernatant collected from cultures of myocytes and lymphocytes had the same effect on myocytes contractility as observed following exposure of myocytes to cytotoxic lymphocytes. CONCLUSIONS: This supports our hypothesis that these physiological alterations observed in myocytes are mediated by a soluble factor secreted by cytotoxic lymphocytes.

Action Potentials↗
PubMed1994

Total coronary artery occlusion late after successful coronary angioplasty of moderately severe lesions: incidence and clinical manifestations.

Coronary restenosis after balloon angioplasty is a slow process that develops over a few months. In some patients, with an initially successful angioplasty, an artery that originally had only moderate stenosis becomes totally occluded as a result of restenosis. This report describes 16 such patients out of 415 dilated lesions with late angiographic follow-up. Ten patients presented with stable angina pectoris, 5 had unstable angina and only one was admitted with a small myocardial infarction. Visible collaterals were present in 15 patients. Except for the patient who sustained myocardial infarction, none of the late angiograms showed the typical morphological features of acute lesion. We conclude that total coronary occlusion late after successful angioplasty of an artery that was moderately narrowed is rare. The 'restenotic' occlusion is a slow process that stimulates collateral formation and thus the risk of myocardial infarction is small.

Adult↗
PubMed1994

Sigma receptor ligands modulate contractility, Ca++ influx and beating rate in cultured cardiac myocytes.

Specific binding of [3H]-1,3-di-o-tolylguanidine (DTG) and (+)-[3H]-(3-hydroxyphenyl)-N-(1-propyl)-piperidine [(+)-3-PPP] to membranes of cultured cardiac myocytes from neonatal rats revealed the presence of sigma receptors on these cells. Exposure of cultured cardiomyocytes to nanomolar concentrations of (+)-3-PPP, (+)-pentazocine and haloperidol induced specific patterns of changes in contractility of electrically paced cultures. The amplitude of systolic cell-motion (ASM) decreased by 10 to 25% 1 to 2 min after drug addition, then transiently increased (3-10 min) and finally decreased to about 75% of control level. Fluorescence measurements on indo-1 loaded cardiomyocytes revealed drug-induced changes in the size of the concentration of free cytosolic calcium ([Ca++]i)-transients, similar to the changes observed in ASM. These changes appear to be mediated by corresponding changes in the rates of 45Ca++ influx which increased 2 to 7 min after the addition of (+)-3-PPP and decrease to 50% of the control level thereafter. Preincubation with thapsigargin, which depletes the sarcoplasmic reticulum-Ca++ stores, did not affect the pattern of changes in ASM, induced by the subsequent addition of (+)-3-PPP. This indicates that the changes in [Ca++]i are not mediated by sarcoplasmic reticulum-Ca++ transport systems. Exposure to sigma ligands did not affect the apparent sensitivity of the myofilaments to Ca++, as indicated by the relationships between changes in ASM and in [Ca++]i-transients. Cultures which were not paced, contracted spontaneously at a constant rhythm. Sigma receptor ligands caused changes in beating frequencies which were followed by irregular contractions.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Very early thrombolysis in acute myocardial infarction--a light at the end of the tunnel.

Myocardial damage in acute myocardial infarction is a time-dependent process. Thrombolytic therapy effectively opens the coronary artery, restores coronary blood flow and prevents ongoing necrosis. We examined the effect of very early thrombolytic therapy (including prehospital administration) in a consecutive group of 510 patients with myocardial infarction on the following factors: mortality, complications and the preservation of left ventricular function. The treatment was given to 89 at home (time delay to treatment 1.2 +/- 0.6 h) and 421 in hospital (2.0 +/- 1.0 h). Twelve patients died in hospital and major hemorrhage occurred in 10. The arterial patency rate in 416 patients who underwent coronary angiography 6 days later was 82%. Infarct size measured by left ventriculography was determined by the area at risk, the delay time until the initiation of thrombolytic therapy, the total duration of ischemic pain and the degree of restoration of arterial blood flow. We conclude that early thrombolytic therapy, particularly prehospital management, is feasible and safe and reduces infarct size and mortality. A further decrease in the delay to initiation of treatment and more effective thrombolytic therapy will further decrease mortality and myocardial damage.

Aged↗
PubMed1993

Opioid effects on contractility, Ca(2+)-transients and intracellular pH in cultured cardiac myocytes.

Morphine, the opioid-agonist, and the antagonists naloxone and levallorphan exerted direct effects on spontaneously-contracting cultures of cardiac myocytes from neonatal rats. Naloxone and levallorphan induced an increase in the amplitude of systolic cell motion (ASM) and in the size of [Ca2+]i-transients, measured as indo-1 fluorescence ratio (IFR), whereas morphine caused an increase in IFR with no change in ASM. Both morphine and naloxone caused a transient increase in 45Ca2+ influx into the cardiomyocytes. Analysis of the relationship between changes in ASM and IFR indicated dual action of the drugs: (a) An increase in [Ca2+]i-transients elicited by morphine and the antagonists, apparently resulting from a transient increase of Ca2+ influx. (b) Altered myofibril responsiveness to Ca2+; the agonists decreased it, and the antagonists increased it. Intracellular pHi measurements in cardiomyocytes loaded with the fluorescent indicator BCECF revealed that morphine caused acidosis and the antagonists caused alkalosis. These pH changes were inhibited by pertussis-toxin, protein kinase inhibitor K323a, phorbol-ester and ethylisopropyl-amiloride, indicating pathways mediated by GTP-binding proteins and altered activities of protein kinase C and Na+/H+ exchanger. Preincubation with pertussis toxin prior to the addition of morphine prevented the decrease in the myofibril responsiveness to Ca2+ as well as the decrease in pHi but did not affect the increase in [Ca2+]i-transients and the increase in the rate of Ca2+ influx. As a result, addition of morphine after preincubation with pertussis toxin caused a positive inotropic effect. Our results indicate that morphine acts by two different pathways distinguishable by their sensitivity to pertussis toxin (1), increased Ca2+ influx leading to increased Ca(2+)-transients and (2) decreased intracellular pH leading to reduced myofibril responsiveness to Ca2+.

Acidosis↗
PubMed1993

Intra-aortic balloon counterpulsation improves survival in cardiogenic shock complicating acute myocardial infarction.

The impact of intra-aortic balloon counterpulsation (IABC) on survival of patients with acute myocardial infarction (AMI) complicated by cardiogenic shock (CS) has been evaluated in this study of 85 patients. IABC was available for the 24 group A patients (and used in 20 patients). IABC was not available for the 21 group B patients who presented simultaneously with similar clinical characteristics and received identical pharmacological treatment. In-hospital and one year survival was significantly higher in group A (46% and 38% vs 19% and 10%, P < 0.001). Sixteen out of the 20 (group A1) IABC patients received early coronary revascularization. During 1980-1984, 35 patients with AMI and CS received IABC (group C) but none underwent early revascularization. There was no difference in in-hospital or one-year survival between group A1 (50% and 40%) and group C (45% and 40%). We conclude that early IABC improves survival of patients with AMI complicated by CS.

Combined Modality Therapy↗
PubMed1993

Cardiac rupture during coronary angioplasty.

Cardiac rupture is a catastrophic complication of acute myocardial infarction. We describe a patient with acute myocardial infarction who received thrombolytic therapy and then developed cardiac rupture and tamponade during rescue angioplasty.

Angioplasty, Balloon, Coronary↗
PubMed1993

Heat acclimation improves cardiac mechanics and metabolic performance during ischemia and reperfusion.

Cardiac mechanics and metabolic performance were studied in isolated perfused hearts of heat-acclimated (AC) rats (at 34 degrees C for 1 mo) and their age-matched controls (C). Diastolic and systolic pressures, coronary flow, and the appearance of ischemic contracture (IC) were measured during progressive graded ischemia, total ischemia (TI), and reperfusion. ATP, phosphocreatine, and intracellular pH were measured during TI and reperfusion with the use of 31P-nuclear magnetic resonance spectroscopy. Systolic pressure was greater in AC hearts than in C hearts (P < 0.0001). During 50% of perfusion pressure 15 and 46% of AC and C hearts, respectively, showed IC (P < 0.001). During 25% of perfusion pressure 85% of the hearts in both groups developed IC. The onset of IC in AC hearts was delayed compared with in C hearts. On reperfusion 93 and 66% of AC and C hearts, respectively, resumed contraction. Recovery of diastolic pressure was 78 and 36% for the AC and C hearts, respectively (P < 0.05). During TI ATP declined by 0.94 and 1.20 mumol/min in AC and C hearts, respectively, resulting in 21 +/- 2.8% preservation of the ATP pool in AC hearts after 30 min of TI (P < 0.001). The AC group also showed a delayed decline in intracellular pH (P < 0.001). The data suggest beneficial effects of heat acclimation on the heart, which were exhibited by greater pressure generation and by the emergence of protecting features during ischemia and reperfusion, possibly via energy-sparing mechanisms.

Acclimatization↗
PubMed1992

Autodecremental pacing for the interruption of ventricular tachycardia and atrial flutter.

The efficacy and safety of autodecremental pacing (ADP) to interrupt ventricular tachycardia (VT) and atrial flutter was examined. Once tachycardia was recognized, ADP was initiated using a short train of stimuli with gradual shortening (3%) of the interstimulus interval. ADP was applied to 13 consecutive patients during 75 episodes of VT (mostly following induction by ventricular stimulation). Successful interruption of VT occurred in 88% of the episodes. In 6 episodes (8%), ADP resulted in ventricular fibrillation and in 3 episodes VT was unaffected by ADP. The only significant discriminator between the failure or success of ADP was the rate of VT. ADP was also applied to 17 consecutive patients with an atrial flutter that was resistant to conventional antiarrhythmic agents. Successful conversion of atrial flutter to sinus was seen in only 8 patients (47%). A temporary acceleration to atrial fibrillation appeared in 3 patients (18%), and in 6 patients atrial flutter was unaffected by ADP. ADP was successful in 70% (7/10) of patients with type 1 (< 300 beats/min) atrial flutter. The authors conclude that ADP is beneficial in the interruption of VT and atrial flutter in a selected group of patients, especially with a slower rate of tachyarrhythmia (atrial rate during atrial flutter < 300 beats/min and ventricular tachycardia < 180 beats/min).

Adult↗
PubMed1992

Relationship between ATP resynthesis and calcium accumulation in the reperfused rat heart.

1. The postulate that the composition of solutions used to reperfuse ischaemic hearts may modulate their ability to synthesize high-energy compounds was tested in isolated rat hearts subjected to 30 min normothermic ischaemia and then reperfused with either Krebs'-Henseleit buffer (K-H) for 20 min (control reperfusion, CR), or a 'myocardial protective solution' (MPS) for 5 min, followed by 15 min K-H (modified reperfusion, MR). The 'myocardial protective solution' was designed to protect against damage caused by sodium and calcium accumulation and by free radicals. Metabolic precursors were also included to promote and support adenosine triphosphate (ATP) resynthesis during reperfusion under both aerobic and hypoxic conditions. 2. 31P nuclear magnetic resonance (NMR) was used to measure tissue ATP and creatine phosphate (CP), and atomic absorption spectrometry was used to measure Ca++. Early during CR, ATP recovered to 28% of the pre-ischaemic value, but fell to 5.5% with continued perfusion. Similarly, CP recovered to 45.5% of the pre-ischaemic level during early CR but fell to 25.5% with continued perfusion. 3. Better maintenance of ATP was seen during MR with oxygenated MPS (O2-MR), the final ATP remaining at 16.9% of the pre-ischaemic level. During O2-MR, CP recovered to 43.55 of the pre-ischaemic level but was not maintained and fell to a final level of 29.5%. 4. During MR with O2-free MPS (non-O2-MR), there was no reperfusion-associated fall in ATP or CP, with the levels maintained at 26.6% and 34.55, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗