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Biomedical subjects

C W Hogue

Publications and source records attributed to C W Hogue.

At least 19 recordsLinked to original sources
PubMed2001

Systematic genetic analysis with ordered arrays of yeast deletion mutants.

In Saccharomyces cerevisiae, more than 80% of the approximately 6200 predicted genes are nonessential, implying that the genome is buffered from the phenotypic consequences of genetic perturbation. To evaluate function, we developed a method for systematic construction of double mutants, termed synthetic genetic array (SGA) analysis, in which a query mutation is crossed to an array of approximately 4700 deletion mutants. Inviable double-mutant meiotic progeny identify functional relationships between genes. SGA analysis of genes with roles in cytoskeletal organization (BNI1, ARP2, ARC40, BIM1), DNA synthesis and repair (SGS1, RAD27), or uncharacterized functions (BBC1, NBP2) generated a network of 291 interactions among 204 genes. Systematic application of this approach should produce a global map of gene function.

Carrier Proteins↗
PubMed2001

Sex differences in neurological outcomes and mortality after cardiac surgery: a society of thoracic surgery national database report.

BACKGROUND: The purpose of this study was to evaluate whether women undergoing cardiac surgery are more likely to suffer neurological complications than men and whether these complications could explain, at least in part, their higher perioperative mortality. METHODS AND RESULTS: The Society of Thoracic Surgery National Cardiac Surgery Database was examined for the years 1996 and 1997 to determine the frequency of new neurological events (stroke, transient ischemic attack, or coma) occurring after cardiac surgery. We reviewed clinical information on 416 347 patients (32% women) for whom complete neurological outcome data were available. New neurological events after surgery were higher for women than for men (3.8% versus 2.4%, P=0.001). For the whole group, the 30-day mortality was higher for women than for men (5.7% versus 3.5%, P=0.001), and among those patients who suffered a perioperative neurological event, mortality was also significantly higher for women than men (32% versus 28%, P=0.001). After adjustment for other risk factors (eg, age, history of hypertension and/or diabetes, duration of cardiopulmonary bypass, and other comorbid conditions) by multivariable logistic regression, female sex was independently associated with significantly higher risk of suffering new neurological events after cardiac surgery (OR 1.21, 95% CI 1.14 to 1.28, P=0.001). CONCLUSIONS: Women undergoing cardiac surgery are more likely than men to suffer new perioperative neurological events, and they have higher 30-day mortality when these complications occur. The higher incidence of perioperative neurological complications in women cannot be explained by currently known risk factors.

Adult↗
PubMed2001

BIND--The Biomolecular Interaction Network Database.

The Biomolecular Interaction Network Database (BIND; http://binddb. org) is a database designed to store full descriptions of interactions, molecular complexes and pathways. Development of the BIND 2.0 data model has led to the incorporation of virtually all components of molecular mechanisms including interactions between any two molecules composed of proteins, nucleic acids and small molecules. Chemical reactions, photochemical activation and conformational changes can also be described. Everything from small molecule biochemistry to signal transduction is abstracted in such a way that graph theory methods may be applied for data mining. The database can be used to study networks of interactions, to map pathways across taxonomic branches and to generate information for kinetic simulations. BIND anticipates the coming large influx of interaction information from high-throughput proteomics efforts including detailed information about post-translational modifications from mass spectrometry. Version 2.0 of the BIND data model is discussed as well as implementation, content and the open nature of the BIND project. The BIND data specification is available as ASN.1 and XML DTD.

Binding, Competitive↗
PubMed2001

Mechanisms and attenuation of hemostatic activation during extracorporeal circulation.

Patients undergoing cardiac surgery with cardiopulmonary bypass are at risk for excessive microvascular bleeding, which often leads to transfusion of allogeneic blood and blood components as well as reexploration in a smaller subset of patients. Excessive bleeding after cardiac surgery is generally related to a combination of several alterations in the hemostatic system pertaining to hemodilution, excessive activation of the hemostatic system, and potentially the use of newer, longer-acting antiplatelet or antithrombotic agents. Although several nonpharmacologic strategies have been proposed, this review summarizes the role of pharmacologic interventions as means to attenuate the alterations in the hemostatic system during CPB in an attempt to reduce excessive bleeding, transfusion, and reexploration. Specifically, agents that inhibit platelets, fibrinolysis, factor Xa and thrombin, as well as broad-spectrum agents, have been investigated with respect to their role in reducing consumption of clotting factors and better preservation of platelet function. Prophylactic administration of agents with antifibrinolytic, anticoagulant, and possibly antiinflammatory properties can decrease blood loss and transfusion. Although aprotinin seems to be the most effective blood conservation agent (which is most likely related to its broad-spectrum nature), agents with isolated antifibrinolytic properties may be as effective in low-risk patients. The ability to reduce blood product transfusions and to decrease operative times and reexploration rates favorably affects patient outcomes, availability of blood products, and overall health care costs.

Antifibrinolytic Agents↗
PubMed2001

Flow dependency of error in thermodilution measurement of cardiac output during acute tricuspid regurgitation.

OBJECTIVE: To evaluate the effect of variable degrees of tricuspid regurgitation on thermodilution cardiac output measurements during changes in venous return. DESIGN: Prospective, controlled animal study. SETTING: University laboratory. PARTICIPANTS: Eight anesthetized mongrel dogs instrumented for simultaneous measurement of cardiac output by thermodilution and ascending aortic electromagnetometry. INTERVENTIONS: Data were collected before and after induction of moderate and severe tricuspid regurgitation. Under each condition, measurements were obtained at baseline and after opening 2 peripheral arteriovenous shunts to increase venous return. MEASUREMENTS AND MAIN RESULTS: Baseline electromagnetic flow ranged from 1.74 to 3.62 L/min (median 2.73 L/min). Moderate and severe regurgitation reduced median electromagnetic flow values by 31% and 51%. Applying generalized estimating equations to model thermodilution cardiac output as a function of electromagnetic flow, arteriovenous shunt, and severity of tricuspid regurgitation revealed that (1) moderate and severe regurgitation changed the slope and intercept of the thermodilution/electromagnetic regression, but the differences between them were not significant, and (2) arteriovenous shunt alone had no effect under any condition. A simplified model independent of shunt and containing just 2 levels of tricuspid regurgitation (none or present) crossed with electromagnetic flow was applied. This analysis showed that regurgitation caused thermodilution to significantly underestimate electromagnetic flow at cardiac outputs > 2.27 L/min (99 mL/kg/min) and overestimate it at flows < 1.02 L/min (44 mL/kg/min). CONCLUSIONS: These data show that acute tricuspid regurgitation may produce underestimation of cardiac output by thermodilution when flow is relatively high, produce overestimation when flow is relatively low, or have minimal effect when flow is in the midrange.

Animals↗
PubMed2001

Occurrence of myocardial ischemia immediately after coronary revascularization using radial arterial conduits.

OBJECTIVE: To assess the incidence of myocardial ischemia in patients receiving radial arterial and left internal thoracic arterial conduits (RA+LITA) during the postrevascularization period. DESIGN: Nonrandomized observational sequential cohort. SETTING: University hospital. PARTICIPANTS: Thirty adult patients, scheduled for elective coronary artery bypass graft surgery with RA+LITA, compared with 30 patients who received saphenous vein graft and left internal thoracic arterial conduits. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Myocardial ischemic episodes were defined as reversible ST-segment depressions or elevations >or=1 mm and >or=2 mm at J +60 msec and lasting >or=1 minute using 2-channel Holter monitoring. During the post-cardiopulmonary bypass period, a significantly higher number of patients with >or=2 mm ischemic episodes (21.7%; p = 0.015) and higher number of >or=2 mm ischemic episodes per hour (0.19 +/- 0.4 episodes/hr; p = 0.03) were observed in the radial artery group versus the comparison group (0% of patients and 0 episodes/hr). During the postoperative period (24 hours), a significantly longer duration of >or=2 mm ischemic episodes was observed in the radial artery group (24 +/- 33 minutes v 8.4 +/- 21 minutes; p = 0.046). Radial artery graft, preoperative calcium antagonists, and pulmonary arterial mean pressure were independent predictors of the duration and area under the ST-segment curve of >or=2 mm ischemic episodes during the postoperative period. CONCLUSION: There is an association between the use of the radial artery graft and the incidence and severity of >or=2 mm postrevascularization ischemic episodes.

Aged↗
PubMed2001

VISTRAJ: exploring protein conformational space.

UNLABELLED: VISTRAJ is an application which allows 3D visualization, manipulation and editing of protein conformational space using probabilistic maps of this space called 'trajectory distributions'. Trajectory distributions serve as input to FOLDTRAJ which samples protein structures based on the represented conformational space. VISTRAJ also allows FOLDTRAJ to be used as a tool for homology model creation, and structures may be generated containing post-translationally modified amino acids. AVAILABILITY: Binaries are freely available for non-profit use as part of the FOLDTRAJ package at ftp://ftp.mshri.on.ca/pub/TraDES/foldtraj/.

Amino Acid Substitution↗
PubMed2001

Atrial fibrillation after coronary artery bypass graft surgery is unrelated to cardiac abnormalities detected by transesophageal echocardiography.

UNLABELLED: Atrial fibrillation is a common complication of coronary artery bypass graft (CABG) surgery that is associated with adverse patient outcomes. We evaluated whether preexisting abnormalities of cardiac structure or function detected with transesophageal echocardiography (TEE) are prevalent in patients later developing atrial fibrillation after CABG surgery. TEE imaging was performed after induction of general anesthesia, but before primary CABG surgery, in 62 consecutive patients without cardiac valvular disease or preexisting atrial fibrillation. Measurements included left atrial diameter, left ventricular wall thickness, left ventricular end-systolic and end-diastolic dimensions and fractional area change. Pulsed-wave Doppler measurements of pulmonary venous and trans-mitral blood flow velocity were obtained. Continuous monitoring with telemetry electrocardiography for the development of atrial fibrillation was performed. Eighteen patients (29%) developed postoperative atrial fibrillation. There were no significant differences in left atrial or left ventricular TEE variables or pulsed-wave Doppler pulmonary venous flow measurements between patients with and without postoperative atrial fibrillation. After adjusting for age and duration of aortic cross-clamping, there were no differences in the transmitral Doppler diastolic filling variables between these same groups. These data suggest that atrial fibrillation commonly occurs after CABG surgery in the absence of atrial enlargement or Doppler-derived cardiac functional abnormalities. The data imply that the use of TEE immediately before surgery would be an insensitive means for routine identification of patients susceptible to this arrhythmia. IMPLICATIONS: Transesophageal echocardiography performed immediately before coronary artery bypass graft (CABG) surgery is not useful for prediction of susceptibility to develop atrial fibrillation postoperatively. Postoperative atrial fibrillation commonly occurs after CABG surgery in the absence of preoperative atrial enlargement or Doppler derived functional abnormalities.

Aged↗
PubMed2001

The relationship between hirudin and activated clotting time: implications for patients with heparin-induced thrombocytopenia undergoing cardiac surgery.

UNLABELLED: Anticoagulation with recombinant hirudin (r-hirudin) (Refludan) has been suggested as an alternative to heparin for patients with heparin-induced thrombocytopenia requiring cardiac surgery. We sought to develop a modified activated coagulation time (ACT) that would allow quantification of the levels of r-hirudin required during cardiopulmonary bypass (CPB). Twenty-one patients scheduled for elective cardiac surgical procedures requiring CPB were enrolled in this IRB-approved study. R-hirudin was added to blood specimens obtained before heparin administration (before CPB) and 30 min after heparin neutralization with protamine (after CPB) to result in concentrations of 0, 2, 4, 6, 7, or 8 microg/mL. Kaolin/ACT and complete blood count measurements were assayed in native specimens (first 10 patients, Phase I) or in specimens mixed with equal volumes of commercial normal plasma (second 11 patients, Phase II). In Phase I, good (r(2) = 0.83) linear relationships between ACT values and r-hirudin concentrations (< or =4 microg/mL) were observed in specimens obtained before CPB. However, ACT values were markedly prolonged (P < 0.0001) by r-hirudin in specimens obtained after CPB, with ACT values generally exceeding the ACT's detection limit (>999 s) at hirudin concentrations >2 microg/mL. In patient specimens mixed with normal plasma (Phase II), ACT/hirudin relationships (i.e., hirudin/ACT slope values obtained with hirudin concentration < or =4 microg/mL) in the post-CPB period (0.022 +/- 0.004 microg. mL(-1). s(-1)) were similar (P = 0.47) to those (0.019 +/- 0.004 microg. mL(-1). s(-1)) obtained in the pre-CPB period. Accordingly, a significant relationship between normal plasma-supplemented ACT values and predilution hirudin concentration was obtained in the post-CPB (hirudin = 0.039ACT - 4.34, r(2) = 0.91) period. Although our data demonstrate that the ACT test cannot be used to monitor hirudin during CPB, the addition of 50% normal plasma to post-CPB hemodiluted blood specimens yields a consistent linear relationship between hirudin concentration and ACT values up to a predilution concentration of 8 microg/mL. Plasma-modified ACT may be useful in monitoring hirudin anticoagulation during CPB. IMPLICATIONS: A modified activated clotting time test system that may be helpful in monitoring hirudin anticoagulation in patients with heparin-induced thrombocytopenia during cardiac surgery with cardiopulmonary bypass is described.

Anticoagulants↗
PubMed2001

Cardiac and neurologic complications identify risks for mortality for both men and women undergoing coronary artery bypass graft surgery.

BACKGROUND: Despite a number of studies showing that women and men respond to coronary artery bypass graft surgery differently, it is not known whether variables associated with mortality are the same for women and men. The purpose of this study was to identify variables independently associated with mortality for women undergoing coronary artery bypass graft surgery. METHODS: Single-institutional data were prospectively collected from 5,113 patients (1,558 or 30.5% women) undergoing coronary artery bypass graft surgery. The database was reviewed for patient characteristics and operative outcomes based on sex. Complications evaluated included low cardiac output syndrome (cardiac index < 2.0 l x min(-1) x m(-2) for > 8 h, regardless of treatment), stroke (new permanent global or focal motor deficits), Q-wave myocardial infarction, postoperative atrial fibrillation, and operative mortality. RESULTS: Women were older than men, and they were more likely to have preexisting hypertension, diabetes, and a history of stroke. Operative mortality for women was higher than for men (3.5% vs. 2.5%, P < 0.05). Compared with men, women were more likely to experience a postoperative myocardial infarction, stroke, and low cardiac output syndrome. When performing analysis on data from both sexes separately, low cardiac output syndrome, new stroke, myocardial infarction, and duration of cardiopulmonary bypass were independently associated with mortality for women and men both. Patient age was not independently associated with risk for mortality for women, but it was for men. However, when the authors combined both sexes in the logistic regression analysis, the age-sex interaction was not significant (P = 0.266), indicating that there was insufficient evidence to assert that age has a different effect on mortality for men and women. CONCLUSIONS: These data confirm that women have higher perioperative mortality after coronary artery bypass graft surgery compared with men. A higher frequency of cardiac and neurologic complications seem to account to a large extent for the higher operative mortality for women. Factors independently associated with perioperative mortality are generally similar for women and men.

Aged↗
PubMed2000

A fast method to sample real protein conformational space.

A fast computer program, FOLDTRAJ, to generate plausible random protein structures is reported. All-atom proteins are made directly in continuous three-dimensional space starting from primary sequence with an N to C directed build-up method. The method uses a novel pipelined residue addition approach in which the leading edge of the protein is constructed three residues at a time for optimal protein geometry, including the placement of cis proline. Build-up methods represent a classic N-body problem, expected to scale as N(2). When proteins become more collapsed, build-up methods are susceptible to backtracking problems which can scale exponentially with the number of residues required to back out of a trapped walk. We have provided solutions to both these problems, using a multiway binary tree that makes the N-body problem of bump-checking scale as NlogN, and speeding up backtracking by varying the number of tries before backtracking based on available conformational space. FOLDTRAJ is independent of energy potentials, other than that implicit in the geometrical properties derived by statistical studies of known structures, and in atomic Van der Waals radii. WHAT-CHECK shows that the program generates chirally and physically valid proteins with all bond lengths, angles and dihedrals within allowable tolerances. Random structures built using sequences from PDB files 1SEM, 2HPR, and 1RTP typically have 5-15% alpha-helical content (according to DSSP) and on the order of 20% beta-strand/extended content. Ensembles of random structures are compared with polymer theory and with experimentally determined fluorescence resonance energy transfer distances. Reasonably sized structure ensembles do sample most of the conformational space available to proteins. The method is also capable of protein reconstruction using Calpha--Calpha direction vectors, and it compares favorably with methods that reconstruct protein backbones based on alpha-carbon coordinates, having an average backbone and Cbeta root mean square deviation of 0.63 A for nine different protein folds. Proteins 2000;39:112-131.

Algorithms↗
PubMed2000

Atrial fibrillation after cardiac operation: risks, mechanisms, and treatment.

Atrial fibrillation (AF) is a common complication of cardiac operations that leads to increased risk for thromboembolism and excessive health care resource utilization. Advanced age, previous AF, and valvular heart operations are the most consistently identified risk factors for this arrhythmia. Dispersion of repolarization leading to reentry is believed to be the mechanism of postoperative AF, but many questions regarding the pathophysiology of AF remain unanswered. Treatment is aimed at controlling heart rate, preventing thromboembolic events, and conversion to sinus rhythm. Multiple investigations have examined methods of preventing postoperative AF, but the only firm conclusions that can be drawn is to avoid beta-blocker withdrawal after operation and to consider beta-blocker therapy for other patients who may tolerate these drugs. Preliminary investigations showing sotalol and amiodarone to be effective in preventing postoperative AF are encouraging, but early data have been limited to selective patient populations and have not adequately evaluated safety. Newer class III antiarrhythmic drugs under development may have a role in the treatment of postoperative AF, but the risk of drug-induced polymorphic ventricular tachycardia must be considered. Nonpharmacologic interventions under consideration for the treatment of AF in the nonsurgical setting, such as automatic atrial cardioversion devices and multisite atrial pacing, may eventually have a role for selected cardiac surgical patients.

Adrenergic beta-Antagonists↗
PubMed2000

BIND--a data specification for storing and describing biomolecular interactions, molecular complexes and pathways.

MOTIVATION: Proteomics is gearing up towards high-throughput methods for identifying and characterizing all of the proteins, protein domains and protein interactions in a cell and will eventually create more recorded biological information than the Human Genome Project. Each protein expressed in a cell can interact with various other proteins and molecules in the course of its function. A standard data specification is required that can describe and store this information in all its detail and allow efficient cross-platform transfer of data. A complete specification must be the basis for any database or tool for managing and analysing this information. RESULTS: We have defined a complete data specification in ASN.1 that can describe information about biomolecular interactions, complexes and pathways. Our group is using this data specification in our database, the Biomolecular Interaction Network Database (BIND). An interaction record is based on the interaction between two objects. An object can be a protein, DNA, RNA, ligand, molecular complex or an interaction. Interaction description encompasses cellular location, experimental conditions used to observe the interaction, conserved sequence, molecular location, chemical action, kinetics, thermodynamics, and chemical state. Molecular complexes are defined as collections of more than two interactions that form a complex, with extra descriptive information such as complex topology. Pathways are defined as collections of more than two interactions that form a pathway, with additional descriptive information such as cell cycle stage. A request for proposal of a human readable flat-file format that mirrors the BIND data specification is also tendered for interested parties. AVAILABILITY: The ASN.1 data specification for biomolecular interaction, molecular complex and pathway data is available at ftp://bioinfo.mshri.on.ca/pub/BIND/Spec/bind.asn. An interactive browser for this document is available through our homepage at http://bioinfo.mshri.on.ca/BIND/asn-browser/.

DNA↗
PubMed2000

Sinus nodal function and risk for atrial fibrillation after coronary artery bypass graft surgery.

BACKGROUND: Nonsurgical patients with sinus node dysfunction are at high risk for atrial tachyarrhythmias, but whether a similar relation exists for atrial fibrillation after coronary artery bypass graft surgery is not clear. The purpose of this study was to evaluate sinus nodal function before and after coronary artery bypass graft surgery and to evaluate its relation with the risk for postoperative atrial arrhythmias. METHODS: Sixty patients without complications having elective coronary artery bypass graft surgery underwent sinus nodal function testing by measurement of sinoatrial conduction time (SACT) and corrected sinus nodal recovery time (CSNRT). Patients were categorized based on whether postoperative atrial fibrillation developed. RESULTS: Twenty patients developed atrial fibrillation between postoperative days 1 through 3. For patients remaining in sinus rhythm (n = 40), sinoatrial conduction times were no different and corrected sinus nodal recovery times were shorter after surgery when compared with measurements obtained after anesthesia induction. Sinus node function test results before surgery were similar between the sinus rhythm and the atrial fibrillation groups. After surgery, patients who later developed atrial fibrillation had longer sinoatrial conduction times compared with the sinus rhythm group (P = 0.006), but corrected sinus nodal recover time was not different between these groups. A sinoatrial conduction time > 96 ms measured at this time point was associated with a 7.3-fold increased risk of postoperative atrial fibrillation (sensitivity, 62%; specificity, 81%; positive and negative predictive values, 56% and 85%, respectively; area under the receiver operator characteristic curve, 0.72). CONCLUSIONS: These data show that sinus nodal function is not adversely affected by uncomplicated coronary artery bypass surgery. Patients who later developed atrial fibrillation, however, had prolonged sinoatrial conduction immediately after surgery compared with patients remaining in sinus rhythm. These results suggest that injury to atrial conduction tissue at the time of surgery predisposes to postoperative atrial fibrillation and that assessment of sinoatrial conduction times could provide a means of identifying patients at high risk for postoperative atrial fibrillation.

Aged↗
PubMed1999

Risk factors for early or delayed stroke after cardiac surgery.

BACKGROUND: Stroke after cardiac surgery is a devastating complication that leads to excess mortality and health resource utilization. The purpose of this study was to identify risk factors for perioperative stroke, including strokes detected early after cardiac surgery or postoperatively. METHODS AND RESULTS: Data were obtained from 2972 patients undergoing coronary artery bypass graft and/or valve surgery. Patients >/=65 years old and those with a history of symptomatic neurological disease underwent preoperative carotid artery ultrasound scanning. Intraoperative epiaortic ultrasound to assess for ascending aorta atherosclerosis was performed in all patients. New strokes were considered as a single end point and were categorized with respect to whether they were detected immediately after surgery (early stroke) or after an initial, uneventful neurological recovery from surgery (delayed stroke). Strokes occurred in 48 patients (1.6%); 31 (65%) were delayed strokes. By multivariate analysis, prior neurological event, aortic atherosclerosis, and duration of cardiopulmonary bypass were independently associated with early stroke, whereas predictors of delayed stroke were prior neurological event, diabetes, aortic atherosclerosis, and the combined end points of low cardiac output and atrial fibrillation. Female sex was associated with a 6.9-fold increased risk of early stroke and a 1.7-fold increased risk of delayed stroke. In-hospital mortality of patients with early (41%) and delayed (13%) strokes was higher than that of other patients (3%, P=0.0001). CONCLUSIONS: Most strokes after cardiac surgery occurred after initial uneventful recovery from surgery. Women were at higher risk to suffer early and delayed perioperative strokes. Atrial fibrillation had no impact on postoperative stroke rate unless it was accompanied by low cardiac output syndrome.

Aged↗
PubMed1999

Antiischemic effects of nicardipine and nitroglycerin after coronary artery bypass grafting.

BACKGROUND: We assessed the efficacy of a continuous infusion of nicardipine and nitroglycerin in reducing the incidence and severity of perioperative myocardial ischemia during elective coronary artery bypass grafting procedures in a prospective, randomized, controlled study. METHODS: Patients received either nicardipine infusion (0.7 to 1.4 microg x kg(-1) x min(-1); n = 30) or nitroglycerin (0.5 to 1 microg x kg(-1) x min(-1); n = 30) or neither medication (n = 17) after aortic occlusion clamp release and for 24 hours postoperatively. Myocardial ischemic episodes (MIE) were considered to have occurred with ST-segment depressions or elevations of at least 1 mm and at least 2 mm (for both depressions or elevations), each at J + 60 ms and lasting at least 1 minute, using a two-channel Holter monitor. RESULTS: Only nicardipine significantly decreased the duration (p = 0.02) of the 1-mm or greater minutes per hour (3.2 +/- 1.2 minutes per hour) and eliminated the number (p = 0.02) of the 2-mm or greater minutes per hour (zero minutes per hour) when compared with control patients (17.2 +/- 5.6 minutes per hour and 0.17 minutes per hour, respectively) during the intraoperative postbypass period. CONCLUSIONS: Our results suggest that nicardipine lessened the severity of myocardial ischemia shortly after coronary revascularization and could be considered as an alternative to standard antiischemic therapy.

Aged↗
PubMed1999

Effects of nicardipine and nitroglycerin on perioperative myocardial ischemia in patients undergoing coronary artery bypass surgery.

Perioperative myocardial ischemic episodes are predictive of adverse cardiac outcomes after coronary artery bypass surgery. We compared the efficacy of continuous infusions of nicardipine (group NIC) and nitroglycerin (group NTG) in reducing the frequency and severity of myocardial ischemic episodes. Patients received either a nicardipine infusion, 0.7 to 1.4 microg/kg/min (n = 30), nitroglycerin infusion, 0.5 to 1 microg/kg/min (n = 30), or neither medication (group C; n = 17) after aortic occlusion clamp release and for 24 hours postoperatively. Myocardial ischemic episodes were considered as ST segment depressions or elevations of 1 mm or greater from baseline, each at J + 60 milliseconds and lasting 1 minute or greater, using a two-channel Holter monitor. Only nicardipine significantly decreased the duration (3.2 +/- 1.2 min/h) and the area under the ST time curve (AUC; 5.7 +/- 15.7 AUC/h) of 1-mm or greater myocardial ischemic episodes compared with group C (17.2 +/- 5.6 min/h and 30.1 +/- 49 AUC/h, respectively) during the intraoperative postbypass period. A trend toward lower frequency, duration, and area under the ST time curve of myocardial ischemic episodes was observed in group NIC compared with group NTG. Cardiac indices and mixed venous oxygen saturations were significantly greater, whereas systemic pressures were less in group NIC compared with group NTG for the same period. These results suggest that nicardipine, but not nitroglycerin, decreased the duration and area under the ST time curve of myocardial ischemic episodes shortly after coronary revascularization. Larger studies are required to verify the efficacy of nicardipine in reducing the severity of myocardial ischemia during cardiac surgery.

Calcium Channel Blockers↗