Do on- and off-pump coronary bypass surgery differently affect perioperative peripheral tissue metabolism?

BACKGROUND

Microdialysis allows the in-vivo assessment of interstitial fluids. We studied the metabolic status of peripheral tissues (skeletal muscle) in patients undergoing coronary artery bypass surgery on- (CABG) or off-pump (OPCAB).

METHODS

Twenty patients candidates to elective coronary bypass surgery were randomly assigned to undergo CABG or OPCAB. A microdialysis catheter was inserted in the left deltoid muscle before surgery and left in place for 24 hours, and metabolic markers of peripheral tissue perfusion (glucose, lactate, pyruvate, glycerol and lactate/pyruvate (L/P) ratio) were assessed before, at the end, and 24 hours after surgery.

RESULTS

Preoperative clinical features were similar in both groups. Interstitial levels of glucose and lactate increased over time, being in both groups significantly higher than baseline 24 hours after surgery, whereas glycerol levels did not change over time and between groups. In addition, there was an increase over time of pyruvate levels which were significantly higher in CABG after surgery, whereas L/P ratio was significantly higher in OPCAB 24 hours after surgery.

CONCLUSION

Metabolic changes after coronary bypass surgery occur with some differences related to CPB use. Overall, these changes suggest that, after coronary surgery, a certain degree of hypermetabolic state ensues, lasting up to 24 hours after surgery; the postoperative increase in pyruvate levels in CABG patients, together with the changes in L/P ratio occurring only in OPCAB patients implies an higher risk of tissue hypoperfusion/ischemia for patients submitted to OPCAB, although this does not lead to permanent cellular damage, as the markers of this complication (e.g., glycerol) do not change over time.

-94 ins/del ATTG NFKB1 gene variant is associated with lower susceptibility to myocardial infarction

BACKGROUND AND AIMS

An imbalance of Nuclear Factor Kappa B (NFкB) and Inhibitor Kappa B (IкB) is involved in various human diseases including atherogenesis. We aimed to evaluate the relationship between NFKB1 and NFKBIA polymorphism and susceptibility to myocardial infarction (MI).

METHODS AND RESULTS

Genotyping was performed for NFKB1 and NFKBIA gene variants in 253 subjects (86 patients affected by myocardial infarction and 167 control subjects). In 40 patients, biopsy specimens were taken from the left ventricle area of presumed ischemia for p50, p65 and IкBα quantification. The allele frequency and genotype distribution of NFKBIA gene polymorphism did not differ between MI and control group while control subjects had a higher D allele frequency of -94 ins/del ATTG NFKB1 polymorphism, compared to the MI group (P<0.001; OR=0.304; 95% CI=0.177-0.522). Subjects carrying the D allele had significantly lower plasma fibrinogen and CRP (C-reactive protein) levels compared to no carriers (P<0.05). Fibrinogen-genotype interaction was found to have a significant effect on susceptibility to myocardial infarction. Myocardial p50 (r=0.627; P=0.012) and p65 (r=0.683; P=0.005) levels significantly correlated with plasma fibrinogen levels while subjects carrying the D allele of the NFкB1 gene variant had lower myocardial p50 (P=0.007) and p65 (P=0.009) levels compared to no carriers.

CONCLUSION

-94 ins/del ATTG NFKB1 gene variant may contribute to lower MI susceptibility via the potential reduction of activated NFкB which in turn is related to plasma inflammatory marker reduction.

[Reconstructive surgery in a case of aneurysm of the ascending aorta and aortic valve insufficiency]

The authors report the case of a young patient with an aneurysm of the ascending aorta and moderate aortic incompetence, who underwent a conservative operation at our institution. Dilatation of the sinotubular junction, particularly at the level of the non-coronary sinus of the aortic valve with loss of coaptation between the corresponding leaflet and the two coronary leaflets, was identified at the time of surgery as major cause of valve insufficiency. During surgery, the dilated ascending aorta and pathologic aortic sinus were replaced with a 26 Hemashield prosthesis tailored according to the David guidelines. An intraoperative post-repair transesophageal echo exam showed that the aortic valve appeared to be working competently. The post-operative course was uneventful and at one year, an echographic check of the aortic valve showed that it was fully competent, with normal leaflet motion. Conservative surgery can be a good option in selected patients with ascending aortic aneurysm and aortic valve insufficiency.

Angiographic and electron-beam computed tomography studies of retrograde cardioplegia via the coronary sinus

Retroperfusion of the coronary sinus does not provide homogeneous distribution of cardioplegic solution. The goal of this study was to analyze the distribution of flow during retrograde cardioplegic infusion in cadaveric human hearts with two different techniques of coronary sinus cannulation: (1) internal occlusion of the coronary sinus by balloon inflation and (2) external occlusion by tightening the orifice of the coronary sinus around a simple catheter. To evaluate differences between the two techniques, angiographic and electron-beam computed tomographic studies were performed. Computed digital angiography was performed on 14 hearts. Angiographic patterns varied according to type of coronary sinus cannulation. With the balloon inflation technique, the marginal vein and the anterior descending vein were perfused first; the posterior descending vein was not perfused. This vein was opacified secondarily through a venovenous anastomosis located at the apex of the heart. Backward flow into the right atrium (steal phenomenon) was demonstrated. At completion of retroperfusion, the inferior part of the septum remained poorly opacified. Conversely, angiographic findings after external occlusion of the coronary sinus revealed simultaneous injection of all venous channels. The entire septum was well opacified at completion of retroperfusion. Electron-beam computed tomographic study was performed on eight hearts with the external occlusion technique and nine with the internal occlusion technique. The computed tomographic findings confirmed the results of digital angiography. The peak myocardial enhancement and the peak rising rate of myocardial enhancement within the interventricular septum were significantly more important (p < 0.0001) when the external coronary sinus occlusion mode was used than when the internal coronary sinus occlusion mode was used. In all hearts except one, the right ventricular wall was not opacified, regardless of the type of cannulation and the type of radiologic analysis. This study demonstrates the importance of coronary sinus cannulation technique in optimizing the protection of the interventricular septum with retrograde cardioplegic infusion.

Transposition of chordae in mitral valve repair. Mid-term results

BACKGROUND

Prolapse of the anterior mitral leaflet, unlike a posterior prolapse, is a difficult lesion to repair. Leaflet plication and triangular resection are satisfactory techniques only in case of a limited prolapse. Chordal replacement has also been proposed but uses foreign material. The purpose of this report is to assess the results of transposition of chordae for the correction of mitral regurgitation (MR) caused by anterior leaflet prolapse.

METHODS AND RESULTS

Between January 1986 and December 1990, 44 adult patients with MR caused by anterior leaflet prolapse underwent repair with transposition of chordae as one of the techniques. This population was retrospectively studied to assess the early and late results of this procedure. Chordae were transferred from the posterior to the anterior leaflet (n = 25) or from an intermediary to a free edge position on the anterior leaflet (n = 21) (two patients underwent both procedures). Two patients died (4.5%). None required early reoperation. Follow-up was complete and ranged from 18 to 82 months (mean, 40.2 +/- 19 months). No patient died during follow-up. Two patients were reoperated on 6 and 8 months after surgery for recurrent MR unrelated to chordal transfer disruption. Doppler echocardiographic studies were available in 95% of the cases at latest follow-up and showed no or minimal MR (0 to 1/4) in 87.5% of the patients and mild MR (2/4) in 12.5%.

CONCLUSIONS

Transposition of chordae appeared to be a simple and safe procedure for correction of anterior mitral prolapse. Transposition of chordae allowed extension of the indications of valve repair. A longer follow-up will be necessary to draw firm conclusions, but mid-term results are encouraging.

Revival of the radial artery for coronary artery bypass grafting

Eighteen years after its first introduction for coronary artery revascularization, the radial artery (RA) was reinvestigated because of unexpected good long-term results in the early series. Since July 1989, 104 patients underwent myocardial revascularization using 122 RA grafts (18 patients received two grafts). The left internal mammary artery (IMA) was concomitantly used as a pedicled graft in 100 cases and the right IMA in 19 cases; a free IMA graft was used in 29 cases and a saphenous vein graft in 24 cases. A mean of 2.8 grafts per patient were performed. Nine patients underwent associated procedures: carotid endarterectomy (3), aortic valve replacement (3), Bigelow procedure (1), and mitral valve repair (2). The target artery receiving the RA was the circumflex (n = 59), diagonal (n = 29), right coronary (n = 27), and left anterior descending (n = 7). One patient died (0.96%) and 2 had perioperative myocardial infarct. Sternal wound infection was noted in 3 cases of double IMA implantation. No ischemia of the hand was observed. All patients received diltiazem started intraoperatively and continued after discharge. In addition aspirin (100 mg/day) was given at discharge. Early angiographic controls (less than 2 weeks) were obtained in the first 50 consecutive patients and revealed 56 of 56 patent RA grafts, 48 of 48 patent left IMA grafts, 11 of 11 patent right IMA grafts, 14 of 18 patent free IMA grafts, and 8 of 9 patent vein grafts.(ABSTRACT TRUNCATED AT 250 WORDS)

Isolated extracardiac unruptured sinus of Valsalva aneurysms

Reports concerning unruptured, isolated aneurysms of one sinus of Valsalva are rare. These aneurysms usually protrude inside the heart and are very rarely extracardiac. We report 4 cases of isolated, unruptured extracardiac aneurysms of the noncoronary sinus of Valsalva. Clinical symptoms were nonspecific. Operation was performed by patch reconstruction of the dilated aortic sinus without replacement of the ascending aorta. Microscopic examination of the diseased aortic wall revealed absence of medial elastic fibers. Late follow-up in all 4 cases revealed a normal ascending aorta with no dilatation of the aortic root and no aortic regurgitation.

[Changes in the vascular wall induced by surgical glues. Experimental study]

The effects on vascular tissues of two different types of surgical glue, gelatin-resorcinol-formaldehyde (GRF) and fibrin (Tissucol) were tested on the rat abdominal aorta. The GRF glue induced destruction of the vascular wall: multiple inclusions of the glue were noted in the media. Conversely, the fibrin glue preserved the normal architecture of the three arterial layers. The use of GRF glue therefore should be avoided on particularly fragile tissues (e.g. coronary arteries), and it seems preferable in such cases to use the fibrin glue.

Dynamic cardiomyoplasty for long-term cardiac assist

The principle of cardiomyoplasty is long-term electrostimulation of a latissimus dorsi muscle (LDM) wrapped around the failing heart. Technically, this procedure consists of placing the left LDM flap around the heart via a window created by partial resection of the 2nd or 3rd rib, and subsequent muscle electrostimulation in synchrony with ventricular systole. The aim of cardiomyoplasty is to support ventricular function in ischemic or dilated cardiomyopathies, or to partially replace the ventricular myocardium after large aneurysm or tumor resections. Our clinical experience at Broussais Hospital involves 44 patients. The functional class and quality of life improved after cardiomyoplasty. Improvement of the ventricular performance and limitation of cardiac dilatation were demonstrated over the long-term. The actuarial survival at 6 years was 71%. Risk factors influencing perioperative mortality were: age > 65 years, associated surgical procedures, pulmonary vascular hypertension, and patients hemodynamically unstable or on inotropic drug support. Preoperative risk factors influencing the long-term mortality were: permanent NYHA functional class 4, cardiothoracic ratio > 0.60, LV ejection fraction < 15%, bi-ventricular heart failure, and atrial fibrillation. Cardiomyoplasty does not preclude the use of future orthotopic heart transplantation.

Penetrating carotid injuries--a wartime experience

Thirty-nine patients with penetrating carotid injuries were treated between 1975 and 1987. All were war victims. On admission 27 (69%) had no neurologic deficit (group I), 8 (20.5%) had a mild neurologic deficit (group II), and 4 (10.5%) had a severe deficit (group III). Repair was undertaken in 38 of 39 (97.5%) patients, and carotid ligation was performed in 1 case (2.5%). Associated injuries were found in 25 (65%) patients. All patients survived. At the time of discharge all group I and II patients had a normal neurologic examination. One patient in group III recovered completely, whereas two had significant improvement. One patient remained unchanged. We conclude that repair should be attempted in all patients with carotid injuries who are seen early (less than 120 minutes) after the accident.