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Biomedical subjects

S Levitsky

Publications and source records attributed to S Levitsky.

At least 37 records · Page 2Linked to original sources

Gender and functional outcome after coronary artery bypass.

BACKGROUND: Female gender is an established risk factor for increased mortality and morbidity after coronary artery bypass graft (CABG) surgery. However, the impact of gender on functional outcome after CABG is not well established. METHODS: Functional status was assessed at baseline and at 6 months with the Duke Activity Status Index (DASI) in 196 consecutive patients undergoing isolated primary CABG. Follow-up data were complete in 158 (81%) patients. The functional status of the 54 (34%) female and the 104 (66%) male patients was compared. RESULTS: The mean DASI score was significantly lower in women at baseline (19.3 +/- 13.8 vs 28.3 +/- 16.8, P = .001) and at 6 months (22.7 +/- 16.3 vs 32.8 +/- 18.2, P = .0007); however, the 6-month change in DASI score (3.3 +/- 16.9 vs 4.5 +/- 20.0, P = .7) was comparable. A similar proportion of women and men (54% vs 53%) had improved above their baseline functional level at 6 months. CONCLUSIONS: These data demonstrate that women undergo CABG at a significantly lower functional level than men; however, the functional improvement after CABG is similar across genders.

Activities of Daily Living↗

Hospital readmission after cardiac surgery. Does "fast track" cardiac surgery result in cost saving or cost shifting?

BACKGROUND: Intense medical and economic pressures have created "fast track" cardiac surgery in which clinical services are streamlined and early discharge is encouraged. Does this strategy promote significant cost saving or merely cost shifting? In a global system of reimbursement, the economic benefit of decreasing patient length of stay may be offset by high rates of patient readmission. This study was undertaken to determine the 30-day readmission rate after cardiac surgery and to analyze trends of readmission diagnoses. METHODS AND RESULTS: From October 1, 1996 to July 31, 1997, 460 consecutive cardiac surgical operations were performed at 1 institution. There were 25 deaths and 8 patients who remained as inpatients at the 30-day postoperative deadline for readmission. Two patients had 2 operations. Therefore, 527 operations were performed on 525 patients. There were 110 readmissions after 527 operations for a readmission rate of 20.9%. A significant number of readmissions (49%) were to outside hospitals. Readmission diagnoses were: atrial fibrillation (23%); angina, congestive heart failure, or ventricular tachycardia (20%); leg wound (15%); sternal wound (5%); pneumonia (5%); gastrointestinal complaints (5%); neurologic event (2%); and miscellaneous (25%). Patients discharged > or = 7 days postoperatively were twice as likely to be readmitted as those discharged on postoperative days 4, 5, or 6. CONCLUSIONS: Readmission after cardiac surgery is common and frequently (49%) to outside institutions. Patients discharged > or = 7 days postoperatively represent the patients at greatest risk of readmission and, therefore, warrant closer scrutiny before discharge.

Adult↗

Clinical and economic impact of diabetes following coronary artery bypass.

BACKGROUND: Diabetes has been shown to have a negative impact on mortality following coronary artery bypass graft (CABG) surgery. This analysis examines the impact of diabetes on additional clinical and economic outcomes. MATERIAL AND METHODS: Between May and October of 1996, 312 consecutive patients undergoing isolated primary CABG were followed through hospital discharge. A total of 114 diabetics (37%) and 198 nondiabetics (63%) was evaluated. Among the diabetics, 62 (54%) were insulin requiring and 52 (46%) were treated with oral hypoglycemic agents or with diet alone. RESULTS: The incidences of major clinical complications including death, renal failure, stroke, reexploration for bleeding, and mediastinitis or sternal dehiscence were not significantly different among insulin-requiring diabetics, noninsulin-requiring diabetics, and nondiabetics. However, insulin-requiring diabetics had a significantly longer (P < 0.01) total length of stay compared to both noninsulin-requiring diabetics and nondiabetics (107 +/- 12.7 days vs. 5.6 +/- 1.5 days vs. 6.8 +/- 5.4 days, respectively), a significantly longer (P < 0.01) intensive care unit length of stay (5.3 +/- 12.4 days vs. 1.4 +/- 0.8 days vs. 2.0 +/- 3.9 days, respectively), and significantly greater (P, 0.01) total hospital charges (48.7 +/- 56.1 thousand dollars vs. 29.3 +/- 4.3 thousand dollar vs. 32.9 +/- 18.9 thousand dollars, respectively). There were no significant differences between the noninsulin-requiring diabetics and the nondiabetics with regard to these clinical and economic outcomes. CONCLUSIONS: Diabetics treated with oral hypoglycemic agents or with diet alone have clinical and economic outcomes similar to nondiabetics following CABG. Insulin-requiring diabetes, however, predicts significantly increased hospital resource utilization. Future outcome assessment and resource utilization analyses must stratify diabetes by treatment to be completely accurate.

Aged↗

Adenosine-enhanced ischemic preconditioning decreases infarct in the regional ischemic sheep heart.

BACKGROUND: Recently we have reported a myoprotective protocol, adenosine-enhanced ischemic preconditioning, that extends the protection afforded by ischemic preconditioning in the isolated crystalloid-perfused heart. In this report the efficacy of adenosine-enhanced ischemic preconditioning in the in situ blood-perfused heart was investigated. METHODS: Sheep were subjected to 60 minutes of regional ischemia and 120 minutes of reperfusion. Ischemic preconditioned hearts received 5 minutes of zero flow regional ischemia and 5 minutes of reperfusion before regional ischemia. Adenosine-enhanced ischemic preconditioned hearts received a bolus injection of 10 mmol adenosine at the immediate start of ischemic preconditioning. Adenosine-treated hearts received an adenosine bolus, 10 minutes before regional ischemia. The ratio of infarct size to area at risk and mechanical function were determined. RESULTS: The infarct size to area at risk ratio in regional ischemia was 55.4%+/-2.1%. This ratio was significantly decreased with ischemic preconditioning and adenosine (22.2%+/-2.2% and 19.3%+/-1.4%, respectively; p < 0.001 versus regional ischemia) and adenosine-enhanced ischemic preconditioning (8.0%+/-2.0%, p < 0.001 versus regional ischemia and ischemic preconditioning, and p < 0.01 versus adenosine). CONCLUSIONS: Adenosine-enhanced ischemic preconditioning significantly decreases infarct size in the in situ blood-perfused heart and provides superior protection compared with ischemic preconditioning.

Adenosine↗

Central venous catheter use in low-risk coronary artery bypass grafting.

BACKGROUND: To assess the impact of central venous pressure catheter monitoring in low-risk coronary artery bypass grafting (CABG), we compared the hospital course of patients undergoing CABG with central venous pressure catheter monitoring with that of similar patients undergoing CABG with pulmonary artery catheter monitoring. METHODS: All isolated primary CABG procedures (n = 312) performed between April 22 and October 31, 1996, were evaluated, and 194 patients meeting six central venous pressure catheter use criteria were identified. Of these 194 patients, 133 (68%) underwent CABG with central venous pressure catheter monitoring, and 61 (32%) had pulmonary artery catheter monitoring owing to surgeon or anesthesiologist preference. RESULTS: In-hospital mortality was similar. A trend toward increased overall complications was seen in the pulmonary artery catheter group. The total volume infused in the first 12 hours, the 24-hour weight gain, and the intubation time were significantly greater in the pulmonary artery catheter group. Increases in intensive care unit length of stay and in total hospital charges trended toward statistical significance in the pulmonary artery catheter group. CONCLUSIONS: Pulmonary artery catheter use in low-risk patients undergoing CABG was associated with greater weight gain and longer intubation time and may be associated with increased morbidity and utilization of hospital resources.

Aged↗

Adenosine-enhanced ischemic preconditioning provides enhanced cardioprotection in the aged heart.

BACKGROUND: Recently we have reported a novel myo-protective protocol "adenosine-enhanced ischemic preconditioning" (APC), which extends and amends the protection afforded by ischemic preconditioning (IPC) by both reducing myocardial infarct size and enhancing postischemic functional recovery in the mature rabbit heart. However, the efficacy of APC in the senescent myocardium was unknown. METHODS: The efficacy of APC was investigated in senescent rabbit hearts and compared with magnesium-supplemented potassium cardioplegia (K/Mg) and IPC. Global ischemia (GI) hearts were subjected to 30 minutes of global ischemia and 120 minutes of reperfusion. Ischemic preconditioning hearts received 5 minutes of global ischemia and 5 minutes of reperfusion before global ischemia. Magnesium-supplemented potassium cardioplegia hearts received cardioplegia just before global ischemia. Adenosine-enhanced ischemic preconditioning hearts received a bolus injection of adenosine in concert with IPC. To separate the effects of adenosine from that of APC, a control group (ADO) received a bolus injection of adenosine 10 minutes before global ischemia. RESULTS: Infarct size was significantly decreased to 18.9%+/-2.7% with IPC (p<0.05 versus GI); 17.0%+/-1.0% with ADO (p<0.05 versus GI); 7.7%+/-1.3% with K/Mg (p<0.05 versus GI, IPC, and ADO); and 2.1%+/-0.6% with APC (p<0.05 versus GI, IPC, ADO, and K/Mg; not significant versus control). Only APC and K/Mg significantly enhanced postischemic functional recovery (not significant versus control). CONCLUSIONS: Adenosine-enhanced ischemic preconditioning provides similar protection to K/Mg cardioplegia, significantly enhancing postischemic functional recovery and decreasing infarct size in the senescent myocardium.

Adenosine↗

Adenosine-enhanced ischemic preconditioning provides enhanced postischemic recovery and limitation of infarct size in the rabbit heart.

OBJECTIVE: The purpose of this study was to determine the effect of an intracoronary bolus injection of adenosine used in concert with ischemic preconditioning on postischemic functional recovery and infarct size reduction in the rabbit heart and to compare adenosine-enhanced ischemic preconditioning with ischemic preconditioning and magnesium-supplemented potassium cardioplegia. METHODS: New Zealand White rabbits (n = 36) were used for Langendorff perfusion. Control hearts were perfused at 37 degrees C for 180 minutes; global ischemic hearts received 30 minutes of global ischemia and 120 minutes of reperfusion; magnesium-supplemented potassium cardioplegic hearts received cardioplegia 5 minutes before global ischemia; ischemic preconditioned hearts received 5 minutes of zero-flow global ischemia and 5 minutes of reperfusion before global ischemia; adenosine-enhanced ischemic preconditioned hearts received a bolus injection of adenosine just before the preconditioning. To separate the effects of adenosine from adenosine-enhanced ischemic preconditioning, a control group received a bolus injection of adenosine 10 minutes before global ischemia. RESULTS: Infarct volume in global ischemic hearts was 32.9% +/- 5.1% and 1.03% +/- 0.3% in control hearts. The infarct volume decreased (10.23% +/- 2.6% and 7.0% +/- 1.6%, respectively; p < 0.001 versus global ischemia) in the ischemic preconditioned group and control group, but this did not enhance postischemic functional recovery. Magnesium-supplemented potassium cardioplegia and adenosine-enhanced ischemic preconditioning significantly decreased infarct volume (2.9% +/- 0.8% and 2.8% +/- 0.55%, respectively; p < 0.001 versus global ischemia, p = 0.02 versus ischemic preconditioning and p = 0.05 versus control group) and significantly enhanced postischemic functional recovery. CONCLUSIONS: Adenosine-enhanced ischemic preconditioning is superior to ischemic preconditioning and provides equal protection to that afforded by magnesium-supplemented potassium cardioplegia.

Adenosine↗

Developmental differences in cytosolic calcium accumulation associated with global ischemia: evidence for differential intracellular calcium channel receptor activity.

BACKGROUND: Cytosolic calcium ([Ca2+]i) accumulation during global ischemia is increased 30% more in the aged compared with the mature heart and is associated with decreased functional recovery. Recently, we have shown that [Ca2+]i accumulation occurs via the ryanodinc sensitive (RyR) and the inositol (1,4,5) triphosphate calcium channels (IP3) but not the Na+/Ca2+ exchanger in both the mature and aged heart, suggesting that the increase in [Ca2+]i accumulation in the aged heart may result from either alteration of intracellular Ca2+ channel receptor activity or abundance. METHODS: [3H]-Ryanodine and [3H]-Inositol (1,4,5) triphosphate binding was determined in mature (MAT; 15 to 20 weeks) and aged (AGE; >130 weeks) rabbit hearts perfused for 60 minutes (control) or perfused for 30 minutes then subjected to 30 minutes of global ischemia (global ischemia). RESULTS: RyR and IP3R activities in control were decreased significantly (P<.05) in aged compared with mature hearts. Global ischemia significantly decreased RyR activity in MAT but not in AGE. IP3R was significantly increased (P<.05) during global ischemia in AGE but not in MAT. Northern and Western blot analysis indicated that there were no differences in RyR or IP3R mRNA or protein levels between MAT and AGE. CONCLUSIONS: Aging alters intracellular Ca2+ channel activity. Ca2+ channel activity is decreased during global ischemia in mature but increased in the aged heart resulting in increased [Ca2+]i accumulation. Differences in RyR and IP3R activities were shown not to be the result of a decrease in receptor mRNA or protein levels in the aged compared with the mature heart.

Animals↗

Amelioration of ischemic calcium overload correlates with high-energy phosphates in senescent myocardium.

Previously, we have shown that potassium and magnesium (K-Mg, 20 mM each) cardioplegia ameliorated cytosolic calcium ([Ca2+]i) accumulation and was associated with enhanced functional recovery after surgically induced global ischemia in the aged heart. K-Mg cardioplegia was also shown to enhance cytosolic cytochrome oxidase I activity and mRNA levels, suggesting that enhanced functional recovery may involve the preservation of high-energy phosphates. To investigate this hypothesis, 31P nuclear magnetic resonance was used to measure serial alterations in phosphocreatine (PCr), inorganic phosphate, nucleoside triphosphate (NTP), intracellular free magnesium (Mgf), and intracellular pH (pHi) in Langendorff-perfused, aged (135 wk) rabbit hearts during preischemia, global ischemia (30 min), and reperfusion (30 min). K-Mg cardioplegia retarded PCr depletion (P < 0.05) and significantly enhanced NTP preservation (P < 0.05) during ischemia and reperfusion. K-Mg cardioplegia also attenuated the increase in Mgf during ischemia (P < 0.05). These results were correlated with amelioration of [Ca2+]i accumulation during ischemia and preservation of left ventricular function after reperfusion and suggest that optimal functional recovery from surgically induced ischemia is provided by K-Mg cardioplegia in the aged myocardium.

Aging↗

Mechanisms of in vitro cardioprotective action of magnesium on the aging myocardium.

Studies examining the effects of aging on the myocardium have indicated that with advancing age there are anatomical, mechanical, ultrastructural, and biochemical alterations which compromise the adaptive response of the heart and make the senescent myocardium less tolerant to surgically-induced ischemia. With the increased incidence of elderly patients as candidates for complex cardiac surgery, the investigation into methods which will increase survivability and enhance myocardial protection are of paramount importance. Previous reports have indicated that surgically-induced global ischemia is associated with alteration in cytosolic calcium accumulation ([Ca2+]i), and that the level of post-ischemic functional recovery can be correlated with control of [Ca2+]i Cardioplegia (high potassium arrest) partially ameliorates the adverse effects associated with global ischemia however; the use of magnesium (magnesium supplemented potassium icardioplegia) has been shown to provide superior myocardial protection during global ischemia and to allow for enhanced post-ischemic functional recovery. The cardioprotective mechanisms of magnesium supplemented potassium cardioplegia which allow for decreased morbidity and mortality in the cardiac surgical patient has been shown to act at the level of the sarcolemma, mitochondria and the nucleus. and may be associated with myocardial gene expression in the aged heart. In this report these mechanisms are reviewed.

Adaptation, Physiological↗

Phorbol-12,13-dibutyrate and pinacidil cardioplegia. Novel forms of myoprotection.

BACKGROUND: Activation of either protein kinase C or the ATP-sensitive potassium channel has been shown to induce the preconditioning response. METHODS AND RESULTS: To investigate whether preconditioning activation adjuvant to hypothermic blood cardioplegia enhances postischemic contractile recovery, 23 adult (0.5 to 1.0 year old) sheep were randomized to receive cardioplegia based on the hyperpolarizing ATP-sensitive potassium channel opener pinacidil, the protein kinase C activator 4 beta-phorbol-12, 13-dibutyrate (PDBu), or standard potassium-magnesium (K1/Mg2+). All groups underwent 60 minutes of 10 degrees C antegrade intermittent blood cardioplegia and 30 minutes of reperfusion. Mechanics were assessed on modified right heart bypass by the preload recruitable stroke work relation and the end-systolic pressure-volume relation. Diastolic function was modeled by the exponential time constant of isovolumic left ventricular pressure decay (Tau) and the "stiffness" coefficient (beta) of the end-diastolic pressure volume relation. Recovery rhythm was defined by the first electrical activity seen during reperfusion. Cardioplegic arrest and preconditioning induced by pinacidil provided superior recovery of contractile function compared with PDBu (100% versus 57% recovery, P < .05) or K+/Mg+ (100% versus 56% recovery, P < .05). Active (Tau) and passive (beta) diastolic function was preserved by all three arrest modalities. Hearts treated with pinacidil demonstrated a rapid recovery of a coordinated contraction pattern, which was offset by a reperfusion tachycardia, whereas PDBu arrest was associated with ventricular fibrillation on reperfusion. CONCLUSIONS: Preconditioning during cardioplegic arrest is agent specific, feasible at cold temperatures, and may be superior to the use of standard K+/Mg2+ cardioplegia.

Animals↗

A brief period of retrograde hyperthermic perfusion enhances myocardial protection from global ischemia: association with accumulation of Hsp 70 mRNA and protein.

The induction of heat shock proteins in the myocardium has been suggested as a possible intervention to allow for enhanced cardioprotection. We examined the cardioprotective effects of Hsp 70 induction in a clinically relevant model, in which a brief period of retrograde hyperthermic perfusion (42 degrees C) was applied for 15 min, only 5 min prior to global ischemia and reperfusion in the isolated perfused rat heart. Our results indicate that in retrograde hyperthermic perfused hearts (n = 17) there was enhanced dP/dT, end diastolic pressure, and peak developed pressure during normothermic reperfusion following 15 min of global ischemia when compared to control hearts perfused at 37 degrees C (n = 18). Northern analysis indicated Hsp 70 mRNA, in retrograde hyperthermic perfused hearts, was increased 9.0 +/- 0./70-fold (P < 0.001) by 30 min and 9.1 +/- 0.45-fold (P < 0.001) by 60 min of normothermic reperfusion. Western analysis revealed that the Hsp, heat inducible 72 kD protein was increased 1.74 +/- 0.35-fold (P < 0.001) by 30 min and 1.79 +/- 0.31-fold at 60 min of normothermic reperfusion when compared to no ischemia hearts. Our results demonstrate that the use of 15 min of retrograde hyperthermic perfusion, only 5 min prior to global ischemia and reperfusion, provide for enhanced myocardial functional recovery. Enhanced myocardial functional recovery was associated with the accumulation of Hsp 70 mRNA and the Hsp 72 kD protein.

Animals↗

Is the preconditioning response conserved in senescent myocardium?

BACKGROUND: Senescent myocardium differs from adult myocardium at both functional and cellular levels. To adjudicate the efficacy of ischemic preconditioning as an alternative or adjuvant myoprotective strategy a reproducible, age-independent, intact laboratory model is necessary. METHODS: Adult (0.5 to 1.0 years) and senescent (5.7 to 8.0 years) sheep underwent 60 minutes of normothermic regional ischemia with 150 minutes of reperfusion. Group II (adult-ischemic preconditioning) and group IV (aged-ischemic preconditioning) underwent preconditioning with three 5-minute episodes of normothermic regional ischemia. Group I (adult-control) and group III (aged-control) were not preconditioned. RESULTS: Risk size and infarct size weights were delineated by monastryl blue pigment infusion and buffered tetrazolium solution. Ischemic preconditioning was evidenced by an infarct size reduction of 54% for adult sheep and 47% for senescent sheep (p < 0.01 versus age-matched controls; p = not significant for adult versus senescent). CONCLUSIONS: The data suggest that the cellular pathways involved with the preconditioning response are well preserved in senescent myocardium and support the utility of the ovine heart model to investigate the clinical relevance of ischemic preconditioning for the increasingly aged population presently undergoing cardiac operations.

Aging↗

Predictors of mortality in pulmonary thromboendarterectomy.

BACKGROUND: The operative mortality associated with surgical thromboendarterectomy of the pulmonary arteries has decreased at the University of California in San Diego with the application of new techniques. For universal performance of the procedure, however, those factors that contribute to the high operative mortality must be identified. We analyzed our results in 34 consecutive patients undergoing pulmonary thromboendarterectomy to determine those preoperative factors that contribute to operative mortality. METHODS: Since 1983, 34 patients with severe, surgically correctable chronic thromboembolic pulmonary hypertension who were judged to be operable by pulmonary arteriography underwent pulmonary thromboendarterectomy. No patient was excluded because of right ventricular failure or hemodynamic severity of disease; the mean pulmonary artery pressure (PAP) was 54 mm Hg, the mean pulmonary vascular resistance (PVR) was 1,094 dynes.s.cm-5, and all patients were in New York Heart Association functional class III or IV. RESULTS: Postoperative course was characterized either by swift recovery (mean length of stay, 13 days) or by rapid demise resulting from pulmonary or right ventricular failure, or both (overall operative mortality, 23%). In survivors, the mean PAP, PVR, cardiac output, and New York Heart Association functional class were significantly improved (p < 0.05). Patients who died had a significantly greater mean preoperative PAP than did those who survived (62.1 +/- 1.2 versus 49.5 +/- 2.3 mm Hg; p < 0.01) and significantly higher PVR (1,512 +/- 116 versus 949 +/- 85 dynes.s.cm-5; p < 0.01). In addition, both a PVR of more than 1,100 dynes.s.cm-5 and a mean PAP of more than 50 mm Hg could accurately predict operative mortality: operative mortality was six times greater in patients with a preoperative PVR of greater than 1,100 dynes.s.cm-5 (41% versus 5.85%) and almost five times greater in those with a mean PAP of greater than 50 mm Hg (37% versus 8%). No intraoperative factors, including the use or duration of circulatory arrest, affected outcome. CONCLUSIONS: Patients with severe hemodynamic disease (PVR > 1,100 dynes.s.cm-5 and PAP > 50 mm Hg) have a high likelihood of operative mortality and perhaps should not undergo pulmonary thromboendarterectomy, except at institutions where the operation is performed frequently.

Adult↗

Reimbursement for cardiac procedures: past, present, and future.

Changes that are the consequences of the transformation of health care into an industry are reviewed. The primary focus is on the effects of this transformation and government finding policies on physician reimbursement for cardiac surgery. Also addressed are Relative Values Scales as the basis for physician reimbursement, physician payment reform under the Omnibus Budget Reconciliation Act of 1989, impact of Medicare policy on surgical volume and surgeon income over recent years, provisions of the Medicare plan under current consideration, and impact of the Congressional-mandated resource-based practice expense relative value scale study currently under way.

Cardiac Surgical Procedures↗