A high-resolution comparative map of porcine chromosome 4 (SSC4).

We used the IMNpRH2(12,000-rad) RH and IMpRH(7,000-rad) panels to integrate 2019 transcriptome (RNA-seq)-generated contigs with markers from the porcine genetic and radiation hybrid (RH) maps and bacterial artificial chromosome finger-printed contigs, into 1) parallel framework maps (LOD ≥ 10) on both panels for swine chromosome (SSC) 4, and 2) a high-resolution comparative map of SSC4, thus and human chromosomes (HSA) 1 and 8. A total of 573 loci were anchored and ordered on SSC4 closing gaps identified in the porcine sequence assembly Sscrofa9. Alignment of the SSC4 RH with the genetic map identified five microsatellites incorrectly mapped around the centromeric region in the genetic map. Further alignment of the RH and comparative maps with the genome sequence identified four additional regions of discrepancy that are also suggestive of errors in assembly, three of which were resolved through conserved synteny with blocks on HSA1 and HSA8.

Investigating the genetic basis of pork tenderness: genomic analysis of porcine CAST.

A quantitative trait locus (QTL) affecting pork tenderness was recently detected within the Illinois Meat Quality Pedigree (IMQP) and fine-mapped to the region of porcine chromosome 2 (SSC2) harbouring the functional candidate gene calpastatin (CAST). To identify molecular variation that may underlie the observed differences in tenderness phenotypes, we characterized the porcine CAST gene and analysed allelic variation within the F(1) boars of the IMQP. The complete genomic sequence of porcine CAST has been determined, and was found to contain 35 exons spanning nearly 123 kb. Using the rapid amplification of cDNA ends (RACE) method, calpastatin transcript types I-III, as well as a putative novel transcript type, were detected within porcine skeletal muscle. Variability in transcription initiation and termination sites was observed, and alternative splicing of exons 1y and 3 was evident. Nearly 77.6% of the CAST gene, including all exons, was re-sequenced from each of six IMQP F(1) boars, and almost 900 polymorphisms were identified. The heterozygosity of nearly 400 polymorphisms appeared to be concordant with the previous QTL data, and the location of this variation within the CAST gene suggests that a causative mutation is likely to be regulatory. Functional characterization of CAST variation should enhance understanding of the molecular basis of pork tenderness, and thus allow for genetic improvement of pork products. The effectiveness of CAST polymorphisms for marker-assisted selection of pork tenderness can now be assessed.

High-resolution comprehensive radiation hybrid maps of the porcine chromosomes 2p and 9p compared with the human chromosome 11.

We are constructing high-resolution, chromosomal 'test' maps for the entire pig genome using a 12,000-rad WG-RH panel (IMNpRH2(12,000-rad))to provide a scaffold for the rapid assembly of the porcine genome sequence. Here we present an initial, comparative map of human chromosome (HSA) 11 with pig chromosomes (SSC) 2p and 9p. Two sets of RH mapping vectors were used to construct the RH framework (FW) maps for SSC2p and SSC9p. One set of 590 markers, including 131 microsatellites (MSs), 364 genes/ESTs, and 95 BAC end sequences (BESs) was typed on the IMNpRH2(12,000-rad) panel. A second set of 271 markers (28 MSs, 138 genes/ESTs, and 105 BESs) was typed on the IMpRH(7,000-rad) panel. The two data sets were merged into a single data-set of 655 markers of which 206 markers were typed on both panels. Two large linkage groups of 72 and 194 markers were assigned to SSC2p, and two linkage groups of 84 and 168 markers to SSC9p at a two-point LOD score of 10. A total of 126 and 114 FW markers were ordered with a likelihood ratio of 1000:1 to the SSC2p and SSC9p RH(12,000-rad) FW maps, respectively, with an accumulated map distance of 4046.5 cR(12,000 )and 1355.2 cR(7,000 )for SSC2p, and 4244.1 cR(12,000) and 1802.5 cR(7,000) for SSC9p. The kb/cR ratio in the IMNpRH2(12,000-rad) FW maps was 15.8 for SSC2p, and 15.4 for SSC9p, while the ratio in the IMpRH(7,000-rad) FW maps was 47.1 and 36.3, respectively, or an approximately 3.0-fold increase in map resolution in the IMNpRH(12,000-rad) panel over the IMpRH(7,000-rad) panel. The integrated IMNpRH(12,000-rad) andIMpRH(7,000-rad) maps as well as the genetic and BAC FPC maps provide an inclusive comparative map between SSC2p, SSC9p and HSA11 to close potential gaps between contigs prior to sequencing, and to identify regions where potential problems may arise in sequence assembly.

A single-base change in the tyrosine kinase II domain of ovine FGFR3 causes hereditary chondrodysplasia in sheep.

Ovine hereditary chondrodysplasia, or spider lamb syndrome (SLS), is a genetic disorder that is characterized by severe skeletal abnormalities and has resulted in substantial economic losses for sheep producers. Here we demonstrate that a non-synonymous T>A transversion in the highly conserved tyrosine kinase II domain of a positional candidate gene, fibroblast growth factor receptor 3 (FGFR3), is responsible for SLS. We also demonstrate that the mutant FGFR3 allele has an additive effect on long-bone length, calling into question the long-standing belief that SLS is inherited as a strict monogenic, Mendelian recessive trait. Instead, we suggest that SLS manifestation is determined primarily by the presence of the mutant FGFR3 allele, but it is also influenced by an animal's genetic background. In contrast to FGFR3 mutations causing dwarfism in humans, this single-base change is the only known natural mutation of FGFR3 that results in a skeletal overgrowth phenotype in any species.

Role of intracoronary ultrasound after high-pressure stent implantation.

BACKGROUND: Poststent high-pressure balloon inflation has been shown to improve clinical outcomes. However, it is unknown whether intracoronary ultrasound (ICUS) provides additional clinical guidance after initial high-pressure balloon inflation is used during stent placement. Thus the purpose of this study was to determine if stent deployment techniques are improved with ICUS imaging despite an optimal angiographic result achieved with high-pressure balloon inflation. METHODS AND RESULTS: Prospective data were collected on 96 consecutive patients in whom 151 stents were deployed. Stents and high-pressure balloons were angiographically sized 1:1 by visual estimation. High-pressure (> or =12 atm in all cases) balloon inflations were continued until angiographic completion (<10% residual stenosis), after which index ICUS imaging was performed. Stent apposition, symmetry, and lumen dimensions were evaluated. An optimal ICUS result was defined as full apposition of the stent, symmetry ratio > or =0.80, and acute gain > or =0.80 of the reference lumen area. If inadequate ICUS results were found, further dilations with higher pressures or larger balloons and subsequent stent reevaluation with ICUS were performed. Sixty-nine (46%) stents required additional balloon inflations. Of these stents, 35 (23%) had initial acute gains that were <80% of the reference lumen area. Forty-six (30%) stents were found to have unapposed struts and 24 (16%) had a symmetry ratio <0.80. In patients requiring additional inflations, minimum stent area increased from 7.6 +/- 2.2 mm(2) to 9.2 +/- 2.4 mm(2) (P <.0001). Similarly, complete stent apposition improved from 33% to 68% of total stents (P <.0001). After initial ICUS, higher-pressure dilations were performed in 40 patients, whereas larger balloons greater than or equal to ICUS reference vessel diameter were used in 33 patients. Follow-up was obtained in 95 (99%) patients. The overall major adverse cardiac event rate at 6 months was 9.3%, which consisted of 8 target vessel revascularizations and 1 abrupt closure requiring repeat intervention. CONCLUSIONS: Even when poststent high-pressure balloon inflation achieves an optimal angiographic result, ICUS assists in optimizing acute gain, symmetry, and apposition of intracoronary stents in approximately 50% of patients. Moreover, ICUS guidance is associated with low rates for target vessel revascularization and major adverse cardiac events at 6-month follow-up.

Comparison of immediate and in-hospital results of conventional balloon and perfusion balloon angioplasty using intracoronary ultrasound.

Angiographic studies have demonstrated that perfusion balloon percutaneous transluminal coronary angioplasty (PTCA) may result in modestly improved luminal gains and fewer major dissections than conventional balloon PTCA. However, intracoronary ultrasound (ICUS), which is more sensitive than angiography in evaluating the incidence, extent, and severity of dissection, was not used. We randomized 48 patients with 54 coronary stenoses to conventional or perfusion balloon PTCA. Four 2-minute inflations were permitted with conventional balloon PTCA. Two 10-minute inflations were allowed with perfusion balloon PTCA. Quantitative coronary angiography and ICUS were performed before and after treatment. In-hospital clinical events were recorded. Conventional and perfusion balloon PTCA achieved similar improvements in lumen diameter (1.25+/-0.51 vs 1.28+/-0.51 mm) and reductions in percent stenosis (-45+/-21% vs -44+/-15%) by quantitative coronary angiography. Comparable gains in lumen diameter (0.62+/-0.39 vs 0.50+/-0.38 mm) and lumen area (2.70+/-1.96 vs 2.05+/-1.52 mm2) were observed on ICUS. Angiography demonstrated similar rates of any dissection (36% vs 21%) and major dissection (12% vs 7%). ICUS identified a similar incidence of any dissection (60% vs 76%) and type II dissection (52% vs 62%). The relative dissection area was also similar (9.2+/-5.6% vs 7.8+/-5.8%). One conventional balloon patient experienced postprocedural chest pain. No patient in either group died, or had myocardial infarction, abrupt closure, or urgent revascularization.

Prognostic implication of creatine kinase elevation following elective coronary artery interventions.

OBJECTIVE: To determine the prognostic significance of creatine kinase (CK) elevation following elective percutaneous transluminal coronary angioplasty (PTCA). DESIGN: Retrospective cohort study. SETTING: Tertiary care referral center. SUBJECTS: A total of 253 consecutive patients with total CK and CK-MB fraction (CK-MB) elevation (case patients) and 120 patients without CK elevation (controls). Control patients had undergone interventions during the same month and year using the same devices. MAIN OUTCOME MEASURES: In-hospital and late cardiac mortality, subsequent myocardial infarction, and the combined end point of cardiac mortality or myocardial infarction. RESULTS: Patient groups were similar with respect to age, sex, extent of coronary artery disease, left ventricular function, number of lesions treated by PTCA, and mean duration of follow-up (>3.5 years). Cardiac mortality was significantly greater (P=.02) for patients with CK elevation after PTCA. When patients were categorized according to peak CK elevation, cardiac mortality differed significantly among patient groups (P=.007), with increased cardiac mortality observed for patients with high (>3.0 times normal) and intermediate (1.5 to 3.0 times normal) CK elevations. In multivariate analyses, higher peak CK and lower ejection fraction were the most important predictors of increased cardiac mortality (both, P<.001); the relative risk for cardiac mortality was 1.05 (95% confidence interval, 1.03-1.08) per 100-U/L increment increase in CK. CONCLUSIONS: Creatine kinase elevation following elective PTCA is associated with increased late cardiac mortality. This increase in cardiac mortality is independent of clinical variables, severity of heart disease, coronary artery lesion characteristics, interventional devices, and procedural outcomes. Even patients with lesser degrees of CK elevation are at significantly increased risk for late cardiac death.

Influence of coronary atherosclerotic remodeling on the mechanism of balloon angioplasty.

OBJECTIVES: Intracoronary ultrasonography was used to assess coronary arteries before and after balloon percutaneous transluminal coronary angioplasty (PTCA) to determine whether the mode of coronary atherosclerotic remodeling affects the mechanism of balloon dilation. BACKGROUND: Coronary arteries may enlarge or shrink in response to atherosclerotic plaque development. The effect of coronary remodeling on the mechanism of balloon PTCA has not yet been studied. METHODS: Forty-one patients with 47 native de novo coronary artery lesions were studied with a 30 MHz intracoronary ultrasound catheter before and after balloon PTCA. Images were analyzed at the lesion site and the adjacent reference segments. At each site the lumen, vessel, and plaque area and the percent area stenosis were measured. Lesions were separated into two groups based on relative vessel area (lesion vessel area/reference vessel area). A relative vessel area >1.0 defines adaptive enlargement (group 1, n = 25), whereas a relative vessel area < or =1.0 reflects coronary shrinkage (group 2, n = 22). Regression analysis examined whether elastic recoil and the PTCA balloon/vessel area ratio correlated. RESULTS: After balloon PTCA was performed, both the enlargement and shrinkage groups had similar gains in luminal area (2.3 +/- 1.8 mm2 [mean +/- SD] vs 2.8 +/- 1.7 mm2, p = 0.32), reduction in percent stenosis (-19.2% +/- 11.5% vs -14.4 +/- 12.7, p = 0.18), and final lumen area (4.9 +/- 1.7 mm2 vs 4.7 +/- 1.9 mm2, p = 0.73). However, the mechanism of luminal enlargement was different in each group. Reduction in plaque area was significantly greater in the enlargement group (group 1, -2.0 +/- 1.7 mm2 vs group 2, 0.04 +/- 2.2 mm2; p = 0.001), whereas increased vessel area was more important in the shrinkage group (group 1, 0.8 +/- 1.5 mm2 vs group 2, 2.4 +/- 2.3 mm2; p = 0.009). Positive correlation was seen between elastic recoil and the balloon/vessel area ratio in lesions with vessel enlargement (r = 0.80, p < 0.0001). No such correlation was observed in shrinkage vessels (r = 0.28, p = 0.21 ). CONCLUSIONS: The acute luminal gain after balloon PTCA is similar regardless of the type of coronary remodeling. However, the mode of remodeling affects the mechanism of balloon dilation such that enlargement vessels exhibit plaque compression, whereas shrinkage arteries demonstrate vessel stretch. The post-PTCA elastic recoil correlates linearly to the balloon/vessel area ratio in arteries that have undergone adaptive enlargement.

Accurate three-dimensional reconstruction of intravascular ultrasound data. Spatially correct three-dimensional reconstructions.

BACKGROUND: The geometrical accuracy of conventional three-dimensional (3D) reconstruction methods for intravascular ultrasound (IVUS) data (coronary and peripheral) is hampered by the inability to register spatial image orientation and by respiratory and cardiac motion. The objective of this work was the development of improved IVUS reconstruction techniques. METHODS AND RESULTS: We developed a 3D position registration method that identifies the spatial coordinates of an in situ IVUS catheter by use of simultaneous ECG-gated biplane digital cinefluoroscopy. To minimize distortion, coordinates underwent pincushion correction and were referenced to a standardized calibration cube. Gated IVUS data were acquired digitally, and the spatial locations of the imaging planes were then transformed relative to their respective 3D coordinates, rendered in binary voxel format, resliced, and displayed on an image-processing workstation for off-line analysis. The method was tested by use of phantoms (straight tube, 360 degrees circle, 240 degrees spiral) and an in vitro coronary artery model. In vivo feasibility was assessed in patients who underwent routine interventional coronary procedures accompanied by IVUS evaluation. Actual versus calculated point locations were within 1.0 +/- 0.3 mm of each other (n = 39). Calculated phantom volumes were within 4% of actual volumes. Phantom 3D reconstruction appropriately demonstrated complex morphology. Initial patient evaluation demonstrated method feasibility as well as errors if respiratory and ECG gating were not used. CONCLUSIONS: These preliminary data support the use of this new method of 3D reconstruction of vascular structures with use of combined vascular ultrasound data and simultaneous ECG-gated biplane cinefluoroscopy.

Arterial imaging with a new forward-viewing intravascular ultrasound catheter, I. Initial studies.

BACKGROUND: Intravascular ultrasound (IVUS) of arteries is limited by the inability of current instruments to visualize beyond the catheter tip. We have developed a prototype 4-mm-diameter forward-viewing IVUS catheter (Cardiovascular Imaging Systems, Sunnyvale, Calif) that has the ability to provide B-mode cross-sectional ultrasound data for a distance of up to 2 cm distal to the catheter tip. METHODS AND RESULTS: To study the utility of this device, a 20-MHz forward-viewing IVUS catheter was used to examine 13 arterial segments (5 human femoral arteries, 1 human carotid artery, 7 canine arteries) in vitro and 1 phantom. After imaging, all data were compared with histology (Histo). In all cases, the IVUS catheter provided forward-viewing images corresponding to the arterial geometry and demonstrated vascular landmarks and atherosclerotic lesions. There was a good correlation between Histo-determined luminal diameters (LD) and IVUS-determined diameters for a distance of 14 mm ahead of the catheter tip: IVUS LD = 1.0 Histo LD + 1.3 (r = .87). CONCLUSIONS: These preliminary data suggest that a forward-viewing IVUS catheter is feasible, accurate, and useful for evaluation of arterial geometry distal to the catheter tip.

Arterial imaging with a new forward-viewing intravascular ultrasound catheter, II. Three-dimensional reconstruction and display of data.

BACKGROUND: Current intravascular ultrasound (IVUS) catheters provide transverse imaging at the level of the ultrasound transducer. This limits imaging to large-diameter segments without critical atherosclerotic narrowings. We have developed a prototype 20-MHz forward-viewing IVUS catheter that provides two-dimensional sector imaging distal to the catheter tip. A present limitation of this technique is that the catheter must be manually rotated to obtain multiple longitudinal views required to integrate the segment into a three-dimensional matrix. To overcome this, we have developed an algorithm that reconstructs these multiple two-dimensional forward-viewing IVUS images into a three-dimensional matrix for more complete depiction of the segment distal to the ultrasound catheter. This algorithm allows display and multidimensional slicing of the three-dimensional reconstruction. METHODS AND RESULTS. To test our algorithms, five arterial segments (three canine aortas, two human femoral arteries) were evaluated in vitro. In each segment, 36 forward-viewing longitudinal slices were collected, digitized, processed, and reoriented to produce a three-dimensional reconstruction (3DR) matrix. The matrix data were sliced into parallel transverse sections and compared with morphometric interpretation of histological sections (Histo). As a result, image data could be reconstructed for a distance of 2.0 cm ahead of the catheter. 3DR easily demonstrated wall and luminal morphology and provided transverse IVUS images comparable to the histological specimens. A good correlation was noted between Histo- and 3DR-determined luminal diameters (LD) and luminal areas: 3DR LD = 1.4 Histo LD-0.4, r = .86; 3DR LD = 0.7 +/- 0.20 cm (mean +/- SD); and Histo LD = 0.7 +/- 0.13 cm. CONCLUSIONS: These preliminary data demonstrate the feasibility of 3DR of forward-viewing IVUS data. This method allows rapid, detailed analysis of diseased arterial segments previously unavailable with standard IVUS and may permit better targeting of interventional techniques.

Plaque and structural characteristics of the descending thoracic aorta using transesophageal echocardiography.

The in vivo acoustic and structural characteristics of atherosclerosis in the descending thoracic aorta have not been well delineated. We prospectively evaluated the descending thoracic aorta of 147 patients (35 women and 112 men; age, 61 +/- 14 years) who underwent clinically indicated transesophageal echocardiography. Patients with suspected disease of the aorta were excluded. Thirty-eight patients (26%) had protruding plaques (men, 25%; women, 29%). Six patients had mobile intimal densities with the mobile area ranging up to 1 cm2. As expected, aortic lumen area was decreased (plaque-free, 3.53 cm2; plaque, 3.19 cm2; p less than 0.05) and wall area was increased (plaque-free, 1.51 cm2; plaque, 1.92 cm2; p less than 0.05) in the regions of the plaque. However, total arterial area was not increased (plaque-free, 5.04 cm2; plaque, 5.09 cm2; difference not significant) in a compensatory manner as observed in other arterial beds. Plaque gray scale was less than the gray scale of plaque-free wall (plaque-free, 141.2; plaque, 122.7; p less than 0.05) when compared at the same level of the descending thoracic aorta or with a second aortic plaque-free level (plaque-free, 150.4; plaque, 122.7; p less than 0.05). Standard deviation of gray scale level was similar between plaque and normal regions. Unsuspected protruding plaques in the descending thoracic aorta occurred in one quarter of the patients referred for routine transesophageal examination. Plaques tended to have lower echogenicity and were differentiated from plaque-free walls within patients. Plaque formation did not result in increased total arterial area. These data suggest that the degree or character of compensatory atherosclerotic remodeling in the highly elastic descending thoracic aorta may differ from other arterial beds.

Coronary embolism following atrial septal defect repair.

To our knowledge, coronary embolism following repair of atrial septal defect has not been reported previously. A 29-year-old woman had an angiographically documented embolus to the circumflex coronary artery on the fifth postoperative day after pericardial patch repair of a secundum atrial septal defect. This complication might have been prevented by temporary postoperative anticoagulation.

Effects of beta-adrenergic and calcium antagonists on the development of anaphylactoid reactions from radiographic contrast media during cardiac angiography.

Anaphylactoid reactions (ARs) occurring in patients receiving propranolol have been described as unusually severe and having a "sluggish" response to epinephrine. Although the mechanism of ARs to iodinated radiographic contrast media is not IgE mediated, because of widespread use of beta-adrenergic blocking agents, we undertook a prospective study to determine the incidence of AR to radiographic contrast media during cardiac angiography. Nine hundred fifty-two consecutive patients were divided into four groups according to concomitant chronic medications. Group I (447 patients) were receiving no beta-adrenergic blocking agents or calcium antagonists. Group II (216 patients) were receiving a beta-adrenergic blocking agent. Group III (147 patients) were receiving a calcium antagonist but not a beta-adrenergic blocking agent. Group IV (142 patients) were receiving both a calcium antagonist and a beta-adrenergic blocking agent. The reaction rates, respectively, in the four groups were 4.47%, 7.41%, 5.44%, and 4.93%. The rates of ARs were not associated with the use of concomitant medications in any of the groups (chi 2 = 2.531; p = 0.47). The probability of a type II error in comparison of groups I and II was 0.75 should the true incidence of reactions in patients receiving beta-adrenergic antagonists be 7.41%. No difference in the incidence of AR was observed between patients taking selective and nonselective beta-adrenergic blocking agents in group II. Specific ARs occurring in patients receiving beta-adrenergic blocking agents were usually mild and often without need for specific pharmacotherapy.

Comparative study of warfarin versus antiplatelet therapy in patients with a St. Jude Medical valve in the aortic position.

To determine the necessity of long-term warfarin anticoagulation after St. Jude Medical aortic valve replacement in adults, we evaluated the risks of thromboembolism, valve thrombosis, anticoagulant hemorrhage, and sudden cardiac death in two groups of patients. Group I consisted of 41 patients treated with conventional long-term warfarin therapy. Forty-two patients in Group II were treated primarily with antiplatelet therapy (aspirin, dipyridamole, or both); 17 of these patients received warfarin for a short time postoperatively and seven others received it intermittently during the study period. The groups were similar with respect to age, sex, associated cardiovascular disease, and length of follow-up (mean 29 months per patient). In the warfarin-treated group, three late sudden deaths occurred, one of which was preceded by a cerebrovascular accident, for a cardiac mortality of 2.7% per patient-year. There were eight major nonfatal complications (7.3% per patient-year), of which four were hemorrhagic and four embolic. In Group II, there was one sudden cardiac death (1.1% per patient-year) and four major complications occurred (3.2% per patient-year). Two of the complications were embolic and two were episodes of valve thrombosis, both necessitating reoperation. Although the incidence of serious morbidity in the warfarin-treated group was twice that of patients treated with antiplatelet therapy, there were no statistically significant differences in the rates of sudden death or major complications. These data suggest that antiplatelet therapy may be as effective as warfarin in preventing embolism from the St. Jude Medical valve in the aortic position. Valve thrombosis occurred in two patients, both receiving antiplatelet therapy (2.2% per patient-year). Whether this type of valve failure can be prevented by warfarin remains in question.

Pulmonary artery balloon counterpulsation for right ventricular failure: II. Clinical experience.

The use of pulmonary artery balloon counterpulsation (PABC) provided immediate salvage following cardiac surgical procedures in 2 patients with biventricular failure in whom inotropic drugs and intraaortic balloon counterpulsation did not provide sufficient support to allow weaning from cardiopulmonary bypass. Although both patients eventually died, the hemodynamic effectiveness of PABC was documented. The various clinical settings for right ventricular as well as biventricular failure are reviewed, the currently available options for treatment are summarized, and the directions for future laboratory investigation and possible clinical applications are presented.

Effects of myocardial infarction on perioperative cardiac complications.

Of 1104 consecutive noncardiac operations on 981 patients using general anesthesia, 63 were performed on 53 patients who had had a previous myocardial infarction. Patients with a previous infarct were compared to those with no prior infarct to determine the influence of a previous infarct on perioperative cardiac complications. Two of the 53 patients with a previous myocardial infarction (3.8%) had perioperative myocardial infarction, compared to 0.4% (4/928) of patients with no prior history of myocardial infarction (P less than 0.05). Ventricular tachycardia (P less than 0.05) and cardiac death (P less than 0.01) were more frequent in patients with a previous myocardial infarction compared to those with no prior infarct. All patients with a previous myocardial infarction who developed cardiac complications underwent vascular procedures (P less than 0.005) and were over 77 years of age. The two patients who reinfarcted experienced intraoperative hypotension (P less than 0.05). Fourteen of the 53 patients with a history of a myocardial infarction (26.4%) had previous coronary artery bypass surgery; no perioperative cardiac complications occurred in these patients.