Initial clinical trial of substernal epicardial echocardiography: SEEing a new window to the postoperative heart.

BACKGROUND: Postoperative echocardiography windows are often of poor quality because of intervening air spaces around the heart and great vessels. We assessed the utility of a new commercially available adult chest drainage tube that has been modified with the addition of a sterile sleeve to accommodate the introduction of a nonsterile pediatric transesophageal echocardiography (TEE) probe. The TEE probe lies in a substernal epicardial position on the postoperative heart allowing one to perform substernal epicardial echocardiography (SEE). METHODS: Informed consent was obtained from 21 consecutive adult cardiac operation patients. At the completion of the operation the SEE drainage tube was inserted through the rectus muscle and into the pericardium. After chest closure, all patients underwent a full echo examination using an Acuson pediatric biplane probe in the SEE position. Views obtained and ease of insertion were judged on a 1 to 10 (worst to best) scale. RESULTS: Full SEE examinations were completed in an average of 12 minutes. Ease of probe entry and manipulation was excellent (ratings of 9.3 and 9.6, respectively). The quality of the anatomic images was also excellent. Substernal epicardial echocardiography tube positioning was integral to the orientation of the images obtained. There were no complications related to the placement of the SEE tubes or TEE probes. In 4 of 21 patients (19%) the SEE methodology was used serially in the intensive care unit to accurately assess ventricular function and filling during weaning of an intraaortic balloon and inotropic agents. CONCLUSIONS: Substernal epicardial echocardiography is a safe and highly effective methodology for the serial echocardiographic assessment of the postoperative heart.

Effects of potassium channel opener aprikalim on the receptor-mediated vasoconstriction in the human internal mammary artery.

BACKGROUND: Arterial grafts for coronary artery bypass grafting such as the internal mammary artery (IMA) may develop spasm perioperatively. The purpose of this study was to investigate the effects of the potassium channel opener, aprikalim, on the receptor-mediated vasoconstriction in the human IMA in vitro. METHODS: We studied 160 IMA rings taken from coronary artery surgery in organ baths. The interaction between aprikalim and four vasoconstrictors 5-hydroxytryptamine (5-HT), norepinephrine (NE), endothelin-1 (ET-1), and angiotensin II (AII) was investigated in two ways. RESULTS: Aprikalim relaxed IMA rings precontracted by the vasoconstrictors to 66.40 +/- 5.9% for 5-HT (EC50: -6.78 +/- 0.26 LogM), 57.40 +/- 5.5% for NE (-6.54 +/- 0.39 LogM), 81.00 +/- 6.7% for ET-1 (-6.58 +/- 0.26 LogM), and 93.90 +/- 2.5% for AII (-7.80 +/- 0.23 LogM). The relaxation in endothelium-denuded rings contracted by AII was similar to that in the endothelium-intact rings. The relaxation was attenuated by glibenclamide (3 microM) in 5-HT or NE-precontracted IMA. Pretreatment with aprikalim at 1 microM depressed AII-induced contraction (33.20 +/- 7.5% versus 59.70 +/- 7.3%, p < 0.01) but only shifted the curves rightward for 5-HT or NE (EC50 3.1 or 4.3-folds higher, p < 0.05), whereas at 30 microM it also significantly depressed the maximal contraction for 5-HT (35.70 +/- 4.9% versus 103.30 +/- 9.8%, p < 0.001) and NE (90.60 +/- 15.6% versus 125.60 +/- 7.9%, p < 0.05). In contrast, aprikalim did not significantly depress the contraction induced by ET-1 (p > 0.05). CONCLUSIONS: We conclude that aprikalim has vasorelaxant effects on IMA and the effect is vasoconstrictor-selective and endothelium-independent. Aprikalim may provide clinically useful vasorelaxant effects in coronary bypass surgery.

ATP-sensitive potassium channel openers may mimic the effects of hypoxic preconditioning on the coronary artery.

BACKGROUND: This study was designed to investigate the effects of the potassium channel opener KRN4884 in mimicking hypoxic preconditioning on coronary arteries and to explore the possible mechanisms. METHODS: In the organ chamber, porcine coronary artery rings (n = 96) were studied in 6 groups (n = 16 in each group): I. CONTROL: normoxia (pO2 > 200 mmHg); II. Hypoxia-reoxygenation: 60-minute hypoxia (pO2 < 15 mmHg) followed by 30-minute reoxygenation; III. Preconditioning: 5-minute hypoxia followed by 10-minute reoxygenation prior to hypoxia-reoxygenation; IV. KRN4884-pretreatment: KRN4884 (30 microM) was added into the chamber 20 minutes before hypoxia-reoxygenation; V. 5-HD-pretreatment: sodium 5-hydroxydecanoate (5-HD, 10 microM) was given 20 minutes prior to KRN4884-pretreatment; and VI. GBC-pretreatment: glibenclamide (GBC, 3 microM) was added 20 minutes prior to KRN4884-pretreatment. Concentration-contraction curves for U46619 (n = 8 in each group) were constructed. Concentration-relaxation curves for bradykinin (n = 8 in each group) related to endothelium-derived hyperpolarizing factor (EDHF) were established in the rings precontracted with U46619 (30 microM) in the presence of Nomega-nitro-L-arginine (L-NNA, 300 microM) and indomethacin (7 microM). RESULTS: The maximal relaxation induced by bradykinin was reduced in hypoxia-reoxygenation (54.6 +/- 4.3% versus 85.2 +/- 5.7% in control, p = 0.001). This reduced relaxation was recovered in KRN4884-pretreatment (78.9 +/- 3.7%, p = 0.014) or preconditioning (79.9 +/- 3.7%, p = 0.009). 5-HD- but not GBC-pretreatment abolished the effect of KRN4884-pretreatment (78.9 +/- 3.7% versus 53.5 +/- 4.7%, p = 0.009). CONCLUSIONS: Hypoxia-reoxygenation reduces the relaxation mediated by EDHF in the coronary artery. This function can be restored by either hypoxic preconditioning or the potassium channel opener KRN4884. The mechanism of such effect is mainly related to the mitochondrial ATP-sensitive K+ channels.

Vascular endothelial growth factor-mediated endothelium-dependent relaxation is blunted in spontaneously hypertensive rats.

The vasodilatory effect of VEGF has not been characterized in the setting of hypertension. This study investigated the in vitro vasorelaxant effects of VEGF in organ chambers in the aorta of the adult (12-week-old) spontaneously hypertensive rats (SHR), young (4-week-old) SHR without hypertension, and age-matched Wistar-Kyoto (WKY) rats compared with acetylcholine (ACh). Cumulative concentration-relaxation curves were established for VEGF (approximately 10(-12)-10(-8.5) M) and ACh (approximately 10(-10)-10(-5) M) in U46619 (10(-8) M)-induced contraction. VEGF induced endothelium-dependent relaxation that was significantly reduced in the adult SHR compared with the age-matched WKY control (87.8 +/- 2.8 versus 61.4 +/- 8.6%, P = 0.01). These responses were significantly attenuated by pretreatment with N(omega)-nitro-L-arginine (L-NNA, 300 microM) alone (SHR: 25.1 +/- 1.9%; WKY: 21.0 +/- 2.6%; P = 0.01) or indomethacin (7 microM) + L-NNA (SHR: 30.2 +/- 2.1%; WKY: 35.0 +/- 2.9%; P = 0.01). Further addition of oxyhemoglobin (20 microM) abolished the residual relaxation and reduced the relaxation induced by nitroglycerin. ACh induced similar responses to VEGF. In contrast, pretreatment with indomethacin alone enhanced VEGF- or ACh-induced relaxations and the effect was greater in the adult SHR than in WKY rats. In contrast to the adult SHR versus WKY rats, there were no significant differences of VEGF- or ACh-induced relaxations between young SHR and WKY rats. The results demonstrate that VEGF induces endothelium- or nitric oxide-dependent relaxation, which is blunted in the adult SHR. The mechanism of this impairment may be related to decreased release of NO although increased release of contracting factors from the dysfunctional endothelium may also be involved.

Inhibition of vasoconstriction by angiotensin receptor antagonist GR117289C in arterial grafts.

BACKGROUND: Angiotensin II (AII) has been suggested to be one of the important factors for genesis of graft spasm in coronary artery bypass surgery. The aim of this work was to investigate the effects of the nonpeptide angiotensin receptor AT1 antagonist GR117289C on the contraction induced by AII and other vasoconstrictors in isolated human internal mammary artery (IMA) preparations. METHODS: Two hundred eight IMA rings taken from 64 patients undergoing coronary artery bypass grafting were studied in organ baths. The interaction between GR117289C and AII or the other vasoconstrictors (U46619, norepinephrine, endothelin-1, and potassium chloride) was investigated in two ways. RESULTS: GR117289C induced near-maximal relaxation (94.5% +/- 2.9%) in IMA rings precontracted by AII. In IMA rings incubated with 1 or 10 nmol/L GR117289C, contractile responses to AII were attenuated in a concentration-related manner, whereas the dose-response curve did not shift to the right when higher doses of AII were administered, suggesting that the AT1 receptor blockade was noncompetitive in nature. Moreover, GR117289C also induced significant relaxation (82.9% +/- 8.1%) in IMA rings precontracted by U46619, but no inhibitory responses to U46619 could be observed when IMA rings were incubated with GR117289C. GR117289C did not alter responses to potassium chloride, norepinephrine, and endothelin-1. CONCLUSIONS: These results indicate that GR117289C is a potent, selective, noncompetitive AT1 receptor antagonist that may have a possible antagonistic effect on the thromboxane A2 receptor. Because AII and thromboxane A2 are important vasoconstrictors in the genesis of graft spasm, GR117289C may become an alternative treatment to relieve graft spasm.

Extended aortic arch atherectomy.

We report 2 cases of extensive atherosclerosis of the ascending aorta, arch of the aorta, innominate artery, and bilateral carotid arteries treated surgically at St. Vincent and Veterans Administration Medical Centers of Portland, Oregon.

Primary tumors of the aorta.

Primary tumors of the aorta are rare and are usually malignant. Thirty-three cases are reported in the world literature, of which 2 are myxomas. The diagnosis is difficult and is commonly made postoperatively or at autopsy. We present a case of intraluminal aortic myxoma that presented as recurrent arterial emboli and was managed successfully. This case showed the sensitivity of magnetic resonance imaging and transesophageal echocardiography in diagnosis.

Reversed bevel technique for anastomosis at the aortic arch.

We describe a method for performing the distal anastomosis in replacement of the ascending and the proximal arch of the aorta with specific attention to obtaining accurate length and orientation of the graft. This method reduces the incidence of both anastomotic dehiscence due to tension and obstruction caused by redundant graft.

CABG in calcified aorta under circulatory arrest.

Coronary artery bypass grafting in patients with calcified aorta presents a formidable problem in terms of cannulation and proximal anastomosis with its attending risks of cerebral and peripheral embolism. Coronary artery bypass grafting without cross-clamping and proximal anastomosis to the aorta at a soft spot under circulatory arrest may be a simple and safe alternative to a difficult clinical problem.

Adventitial inversion technique in repair of aortic dissection.

We describe a new technique for aortic anastomosis in the repair of acute dissection. The aorta is buttressed by inverting the adventitia without the use of Teflon or other synthetic materials. This technique provides a safe and secure anastomosis.

Mitral insufficiency after pericardiectomy for constrictive pericarditis.

We report the case of a 24-year-old man in whom a clinical syndrome developed while he was on active military duty in Saudi Arabia that was subsequently diagnosed as constrictive pericarditis. Phrenic nerve to phrenic nerve pericardiectomy and posterior pericardial release successfully relieved the ventricular constriction with a resultant increase in the cardiac index from 1.9 to 3.8 L.min-1.m-2. Transesophageal echocardiographic monitoring during the operation disclosed trace mitral regurgitation before median sternotomy. The severity of the regurgitation noticeably increased to the moderate level immediately after pericardial resection. This echocardiographic finding had improved 1 week later, but the regurgitation still was greater than baseline. Mitral valve function had returned to baseline by 4 weeks after the operation. Possible mechanisms of this evolving pattern of perioperative mitral valve dysfunction are discussed.

Traumatic pseudoaneurysm of left internal mammary artery graft.

Traumatic pseudoaneurysm of the left internal mammary artery was recognized as a possible causal factor in the early recurrence of angina in a 51-year-old man. This patient underwent reoperation for revascularization with the left internal mammary artery graft in situ.

Inadequate internal mammary artery graft as a cause of postoperative ischemia: incidence, diagnosis and management.

Inadequate left internal mammary artery (LIMA) graft to the left anterior descending artery (LAD) was encountered in 10 of 3,076 patients between 1984 and July 1990. The mean number of bypass grafts was 2.9 per patient. All patients with inadequate LIMA grafts were stable preoperatively with normal to moderately reduced left ventricular function. No technical difficulties were encountered during surgery. All patients were weaned off cardiopulmonary bypass with minimal or no inotropic support. Each patient developed myocardial ischemia of the LAD territory and/or circulatory collapse or recurrent ventricular dysrhythmia during the first 24 h postoperatively. Six patients, who were immediately re-operated on and had an additional saphenous graft to the LAD, recovered with no infarction and good functional results. Four patients, who were medically treated, developed myocardial infarction. In cases of refractory circulatory collapse and/or ventricular dysrhythmia, inadequate LIMA flow should be suspected. We recommend urgent re-operation with additional saphenous vein graft to the LAD.

Pulmonary vein thrombosis following bilobectomy.

Acute thrombosis of the pulmonary vein following lobectomy or bilobectomy is a rare complication with no standard guideline for diagnosis or management. In this report, we present a case of right upper lobe vein thrombosis following a middle and lower lobectomy. Diagnosis was confirmed by ventilation-perfusion lung scan, pulmonary angiogram, and bronchoscopy. The patient was treated conservatively with no further complications and had a partial recovery of the circulation to the right upper lobe. A review of the literature is also presented along with the experimental data demonstrating the mechanisms of recovery.

An unusual complication of cardiac transplantation--infected aortic pseudoaneurysm.

Infections after cardiac transplantation are a frequent cause of early morbidity and mortality. An unusual site for such a complication is at the aortic anastomotic suture line. We report a case of an infected aortic pseudoaneurysm, seen as recurrent septicemia, during the first 6 months after cardiac transplantation.

Five-year results of coronary bypass grafting for patients older than 70 years: role of internal mammary artery.

Despite numerous references to the superiority of the internal mammary artery (IMA) over the saphenous vein for myocardial revascularization, its role in the elderly is still in question. From January 1984 through December 1988, 1,081 patients older than 70 years (mean age, 74.9 years) underwent bypass grafting, 354 (33%) receiving left IMA grafts based on the surgeon's preference and 727 (67%) receiving vein grafts only. Selection bias resulted in a higher incidence of known risk factors (such as cardiomegaly, arrhythmias, left ventricular failure, wall motion abnormalities, and preoperative combined New York Heart Association/Canadian Cardiovascular Association functional class IV) in patients in whom the IMA was not used. However, unstable angina, acute myocardial infarction, left ventricular dysfunction, and left main disease were not contraindications for using IMA grafts. The operative mortality rate was significantly lower in IMA patients (2.8% versus 7.6%). The actuarial 5-year survival rate (standard error) was higher in patients with IMA grafts, 89% (3%) versus 78% (2%), and postoperative functional class improved to a greater extent in IMA patients (87% of patients were in classes I and II). Arrhythmias and myocardial infarction were significant causes of late death only in patients with vein grafts. When patients are older than 70 years, patient selection factors clearly play an important role in the differential results between patients in whom the IMA is used and patients in whom vein grafts are used. As in younger patients, excellent results can be achieved in the elderly.

Long-term survival after postinfarction bypass operation: early versus late operation.

A study of 832 patients operated on within 30 days of infarction from 1974 to 1987 has resulted in 2,388 patient-years (maximum, 14 years) of prospectively acquired follow-up. This study excludes 74 patients in whom cardiogenic shock was the indication for operation. Five-year survival (+/- standard error) was 84% +/- 2%, 85% +/- 1%, and 90% +/- 1%, and 10-year survival was 71% +/- 4%, 68% +/- 1%, and 78% +/- 1% for patients with acute infarction, remote infarction, and no previous infarction, respectively. Age and left ventricular end-diastolic pressure significantly affected long-term survival for patients with acute infarction by both univariate and multivariate analysis. For patients aged less than 65 years, the 5-year and 10-year actuarial survival rates were 89% +/- 2% and 80% +/- 4%, compared with 75% +/- 3% and 58% +/- 9%, respectively, for patients aged more than 65 years. The survival percentages were 89% +/- 2% and 75% +/- 6% for patients with left ventricular end-diastolic pressure less than 15 mm Hg compared with 77% +/- 5% and 67% +/- 7% for patients with left ventricular end-diastolic pressure greater than 15 mm Hg. Operative mortality was 7.6% for patients operated on within 24 hours, compared with 4.1% for patients operated on between 2 and 30 days after infarction. Ten-year survival was similar (about 70%) for all timing groups. Based on these long-term results, there appears to be little to gain by delaying coronary artery bypass grafting, when indicated, after infarction occurs.

Pseudoaneurysm formation with superior vena caval syndrome 7 years after aortic composite graft placement.

With the advent of the composite graft for combined aortic valve and ascending aortic root operations, post-operative bleeding complications have been reduced. Hemorrhage along the suture sites may occur as a late complication and rarely may originate from the coronary-aortic graft junction. We report a case of a massive pseudoaneurysm, seen as "superior vena caval syndrome," 7 years after operation.