Miguel Josa

Pulmonary embolism after cardiac surgery

OBJECTIVES We examined the incidence of pulmonary embolism after cardiac surgery. BACKGROUND Because venous thromboembolism is considered to be an uncommon complication after cardiac surgery, its incidence was documented in a consecutive series of 1,033 patients who underwent cardiac surgery over a 5-year period. METHODS Parallel cohorts of patients in a tertiary referral center were evaluated and the incidence of pulmonary embolism was compared in subgroups of patients undergoing coronary bypass surgery, valve surgery and combined procedures. RESULTS Pulmonary embolism developed in 33 (3.2%) of the 1,033 cardiac surgical patients, within 2 weeks of a coronary bypass operation in most; it did not develop in any patient who had isolated valve replacement surgery (p < 0.05). The diagnosis of pulmonary embolism was established by pulmonary angiography in 24 patients, ventilation/perfusion lung scan in 3, postmortem examination in 5 and clinical examination in 1 patient. Important risk factors for pulmonary embolism included prolonged postoperative recovery, obesity and hyperlipidemia. The mortality rate was 18.7% in patients with in contrast to 3.3% in those without pulmonary embolism (p < 0.01). CONCLUSIONS Although pulmonary embolism is rare after isolated valve replacement, it is not an uncommon complication after coronary bypass surgery.

The statistical analysis of graft patency data in a clinical trial of antiplatelet agents following coronary artery bypass grafting

Because most coronary artery bypass patients receive more than one graft at surgery, it is most important to determine whether statistical analysis of graft patency should be performed on the premise that the multiple grafts within patients are dependent or independent experimental units. Veterans Administration Cooperative Study No. 207 was a multicenter clinical trial comparing four different antiplatelet regimens to placebo in the prevention of graft occlusion following coronary artery bypass grafting. Using the results from the 1-week postoperative angiograms from the Veterans Administration Cooperative Study No. 207, in which there were 3.2 distal anastomoses per patient, we have tested the hypothesis that grafts within patients tend to act dependently with respect to patency or occlusion by comparing the graft patency data to a binomial distribution (i.e., that distribution that would have been manifest if grafts were independent). Because the graft patency results in Study No. 207 significantly deviated from the binomial distribution (p = 0.0003), a more appropriate analysis for graft patency data was applied using a ratio estimate as applied to cluster sampling. The statistical methods used in 11 previous clinical trials of antithrombotic therapy after coronary artery bypass grafting were examined. Only one of the previous studies used such an analysis, and three additional reports attempted to correct for dependency of grafts within patients in their analyses using other statistical methods. In seven of the studies the investigators did not address the potential problem of a dependent relationship between multiple grafts within patients. We conclude that grafts within patients act as dependent experimental units and that the ratio estimate as applied to cluster sampling may be appropriately applied to these data.

Benign schwannoma of the esophagus presenting as a giant fibrovascular polyp

The case of a 62-year-old man with benign schwannoma associated with a giant polyp of the esophagus is presented. His initial symptom was dysphagia. The polyp was removed through cervical esophagotomy. He had no recurrence of symptoms 5 years after this procedure. Pathologic examination showed a rare histology.

Non-Q wave perioperative myocardial infarction: assessment of the incidence and severity of regional dysfunction with quantitative two-dimensional echocardiography.

Since the widespread use of hypothermic potassium cardioplegia began, marked reductions in perioperative mortality and the rate of Q wave-associated myocardial infarctions have been noted. No study to date has evaluated whether there has been an equally dramatic improvement in the incidence of postoperative myocardial infarctions unassociated with Q wave development. We used a previously validated quantitative two-dimensional echocardiographic analytic algorithm to determine the incidence and severity of regional wall motion abnormalities (RWMAs) and first-pass radionuclide ventriculography to assess deterioration in global left ventricular function in the four following groups of patients (total n = 65): (1) those with peak postoperative creatine kinase (CK)-MB levels equal to or less than the mean value for patients undergoing coronary artery bypass surgery at our institution (n = 10), (2) those with CK-MB levels between the mean and 1 SD above the mean (n = 10), (3) those with peak CK-MB levels higher than 1 SD above the mean (n = 25), and (4) those with new pathologic Q waves on the postoperative electrocardiogram (n = 20). All patients had electrocardiograms without pathologic Q waves and normal wall motion and ejection fraction by contrast ventriculography before surgery. The incidence of postoperative RWMA by two-dimensional echocardiography for groups 1 through 4 was 0%, 20%, 55%, and 89%, respectively. Percent of abnormal left ventricular segments, wall motion scores, and the deterioration in left ventricular ejection fraction as assessed by radionuclide ventriculography were similar for patients with new RWMAs whether or not new Q waves developed (p = NS for all).(ABSTRACT TRUNCATED AT 250 WORDS)

Load tolerance of the right ventricle: Effect of increased aortic pressure*

Right ventricular (RV) failure due to increased RV afterload can be a cause of circulatory compromise. An increase in aortic pressure (Pao) has been reported to improve RV load tolerance. In anesthetized mongrel dogs, we investigated the RV responses to increased afterload, the degree to which RV load tolerance increased with increased Pao, and some of the mechanisms that might be responsible for this. Graded occlusion of the pulmonary artery (PA) was performed to the point of circulatory failure (F). The magnitudo of RV afterload that could be tolerated without F was called the highest load tolerable (HLT). At HLT, PA circumference was reduced by 35.1 ± 3%, and there were increases in RV systolic pressure (from 27.5 ± 0.2 to 63.2 ± 3.4 torr, P

Technetium 99m-labeled tetrofosmin and iodine 123-labeled metaiodobenzylguanidine scintigraphy in the assessment of transmyocardial laser revascularization

OBJECTIVE Transmyocardial laser revascularization is a new technique that improves symptoms in patients with refractory angina not amenable to conventional revascularization. The aim of this study was to assess whether transmyocardial laser revascularization produces changes in innervation, perfusion scintigraphy, or both that could explain the benefit to patients. METHODS Sixteen patients (12 men and 4 women; mean age, 60 +/- 8 years) with coronary artery disease were studied. Transmyocardial laser revascularization was performed in 39 myocardial areas supplied by a stenotic vessel. A technetium 99m-labeled tetrofosmin stress-rest tomographic scan and iodine 123-labeled metaiodobenzylguanidine planar scans were performed before and after transmyocardial laser revascularization (3 and 12 months later) to evaluate myocardial perfusion and innervation. Stress and rest perfusion images were quantified on a polar map. Ischemia uptake was also defined as the difference between rest and stress uptake for each area. Innervation planar images were visually analyzed and semiquantified. RESULTS A significant decrease in angina class from baseline was observed at 3, 6, and 12 months after transmyocardial laser revascularization (P <.005). A significant decrease in ischemia uptake was also found between the pre-transmyocardial laser revascularization and the post-transmyocardial laser revascularization studies in treated areas (P <.001). A significant improvement in stress myocardial perfusion at 3 and 12 months after transmyocardial laser revascularization was only found in treated areas that were considered ischemic in the pre-transmyocardial laser revascularization study (P <.05). At 3 months, a significant myocardial innervation worsening was observed in treated areas (P <.001), with partial recovery at 12 months (P <.05). CONCLUSION The transmyocardial laser revascularization mechanism involves both perfusion improvement and denervation, mainly at 3 months, that partially recovered at 12 months.

Reduction in myocardial acidosis using blood cardioplegia

The composition of the ideal cardioplegic solution is controversial. Blood cardioplegia is an attractive alternative to standard crystalloid solutions, though its superiority in preserving myocardial metabolism has not been demonstrated. Using a new pH electrode system, this study contrasts the effects of blood and crystalloid solutions upon the generation of myocardial acidosis during global ischemia. Thirty-eight mongrel dogs underwent a 120-min period of aortic cross clamping using systemic hypothermia. To maintain myocardial temperature below 15 degrees C, 19 dogs received multiple doses of a bicarbonate containing crystalloid cardioplegic solution (Group I), while 19 dogs received multiple doses of blood cardioplegia (Group II). Myocardial pH and temperature were continuously monitored in the subendocardial region of the left ventricle. There was no difference in baseline pH between Group I (7.13 +/- 0.05) and Group II (7.17 +/- 0.05, P:NS). With systemic cooling and the initial bolus of cardioplegia, myocardial pH rose to 7.42 +/- 0.04 in Group I and 7.42 +/- 0.06 in Group II (P:NS). After 120 min of global ischemia, myocardial pH decreased to 6.61 +/- 0.05 in Group I and 7.07 +/- 0.05 in Group II (P less than 0.001). Blood cardioplegia was most effective during the first hour of aortic cross clamp when myocardial pH rose by 0.13 +/- 0.04 pH units. In contrast, myocardial pH in Group I during the first hour of global ischemia fell -0.35 +/- 0.08 pH units (P less than 0.001 compared to Group II). During the second hour of cross clamp, myocardial pH declined both in Group I (0.26 +/- 0.03 pH units) and in Group II (0.24 +/- 0.05 pH units, P:NS). However, the accumulation of hydrogen ion during the second hour was significantly greater in Group I (+128.0 +/- 21.4 nm/liter) than in Group II (+36.6 +/- 9.0 nm/liter, P less than 0.001). Thus, myocardial acidosis was reduced during the administration of blood cardioplegia when compared to a bicarbonate-buffered crystalloid solution. The salutary effects of blood cardioplegia on myocardial metabolism stem from bloods significant buffering capacity and its ability to deliver oxygen.

Regional Changes in Myocardial Acid Production during Ischemic Arrest: A Comparison of Sanguineous and Asanguineous Cardioplegia

Regional differences in myocardial acid production have not been characterized during administration of either asanguineous or sanguineous cardioplegia. To investigate this, miniature glass pH electrodes were placed in the right ventricular (RV) myocardium, the left ventricular subendocardial (LV endo) region, and the subepicardial (LV epi) region in a canine model. Multiple doses of either blood cardioplegia (Group 1; N = 11) or crystalloid cardioplegia (Group 2; N = 11) were administered during 4 hours of aortic cross-clamping. The accumulation of hydrogen ions during the cross-clamp period was greater in Group 2 than Group 1 in the LV endo region (629 +/- 79 nm/L versus 66 +/- 31 nm/L; p less than 0.001), the LV epi region (623 +/- 66 nm/L versus 72 +/- 32 nm/L; p less than 0.001), and the RV myocardium (814 +/- 296 nm/L versus 150 +/- 54 nm/L; p less than 0.05). Within each group, the time course of myocardial pH and the accumulation of hydrogen ions did not differ among the LV endo region, LV epi region, and the RV myocardium (p = not significant). These data indicate that transmural and interventricular differences in myocardial pH and hydrogen ion accumulation are not produced in the vented, arrested canine heart. In addition, when compared with asanguineous cardioplegia, blood cardioplegia globally and transmurally reduces acid accumulation during ischemic arrest.

Pathogenesis and Prognostic Significance of Conduction Abnormalities after Coronary Bypass Surgery

Of 200 men who underwent isolated coronary bypass graft surgery, 40 (20%) developed new postoperative, persistent conduction abnormalities. The pathogenesis of conduction abnormalities was examined by relating their presence to that of significant proximal left coronary disease before surgery, and to various intraoperative factors that included indices of myocardial preservation and revascularization. Proximal left coronary disease was observed in 92 (46%) of 200 patients, of whom 27 (29%) developed conduction abnormalities. In contrast, of the 108 patients without proximal left coronary disease, only 13 (12%) developed persistent conduction abnormalities (P < 0.01). Intraoperative factors appeared to have little or no role in the development of such abnormalities. It is concluded that the development of persistent postoperative conduction abnormalities is related more to proximal left coronary disease than to intraoperative factors and that such abnormalities do not progress during long-term follow-up (average 53 months).