Effects of coronary revascularization on infarcted myocardial regions--evaluation on postoperative left ventricular regional wall motion during exercise

In order to determine the effects of coronary revascularization for infarcted regions on postoperative left ventricular function and regional wall motion, we studied first-pass radionuclide angiography at rest and during exercise before and after operation in 18 patients with previous myocardial infarction. Preoperative mean value of left ventricular ejection fraction (LVEF) was significantly decreased during exercise from 56.8 +/- 14.1% to 46.1 +/- 15.5% (p less than 0.01). Postoperatively, there was no change of the values between at rest and during exercise: 53.6 +/- 14.1% versus 51.9 +/- 15.7%. Postoperative mean LVEF during exercise was significantly higher, compared with that of preoperative LVEF (p less than 0.05). Mean regional ejection fraction of infarcted regions was significantly decreased during exercise from 66.0 +/- 15.0% to 56.1 +/- 15.8% (p less than 0.01) before operation. However, there was no significant change in values between at rest and during exercise after operation: 65.4 +/- 13.9% versus 61.8 +/- 14.5%. Mean postoperative regional ejection fraction during exercise was significantly higher, compared with preoperative regional ejection fraction after operation (p less than 0.05). These results might be indicated that regional wall motion of the infarcted regions with ischemia enhanced by exercise preoperatively can be definitely improved by coronary revascularization.     

Late results of CABG for postinfarction angina--relation to preoperative myocardial infarct size

We evaluated the late results of coronary bypass grafting (CABG) in 85 patients. The patients were divided into two groups according to preoperative MI size estimated by the Selvester QRS score; 24 with MI size of larger than 20% of LV muscle (group A; average 28 +/- 11%), and 61 with MI size smaller than 20% (group B; average 10 +/- 9%). New York Heart Association classes of both groups following CABG improved significantly (from 2.8 +/- 0.7 to 1.3 +/- 0.4 in group A; p less than 0.01, from 2.5 +/- 0.6 to 1.2 +/- 0.5 in group B; p less than 0.01). There was higher incidence of serious ventricular arrhythmias in group A than in group B (83% vs. 21%, p less than 0.01). In Group A, LVEF and LVESVI did not improve following CABG (from 17 +/- 9 to 16 +/- 8 mmHg, from 39 +/- 15 to 40 +/- 15%, from 66 +/- 28 to 69 +/- 40 ml/M2), while in Group B, those improved significantly (from 13 +/- 6 to 11 +/- 5 mmHg; p less than 0.01, from 53 +/- 14 to 58 +/- 10%; p less than 0.01, from 39 +/- 23 to 32 +/- 14 ml/M2; p less than 0.05). The exercise-to-rest LVSWI ratios increased significantly following CABG in both groups (from 86 +/- 25 to 160 +/- 56% in group A; p less than 0.05, from 92 +/- 31 to 140 +/- 37% in group B; p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

The influence of preoperative anticoagulation on heparin response during cardiopulmonary bypass.

The effect of preoperative anticoagulant therapy on intraoperative heparin response in patients undergoing cardiac operations was examined in a prospective study. The study included 45 patients with different preoperative anticoagulant treatments: 10 patients received treatment with phenprocoumon (a warfarin analogue) (group M), 12 patients received treatment with intravenous heparin (group Hiv), and 13 patients received treatment with subcutaneous heparin (group Hsc). The control group consisted of 10 patients who did not receive anticoagulant therapy before operation (group C). Preoperative antithrombin III activity was highest in group M (85% +/- 6%) and lowest in group Hiv (70% +/- 15%, p less than 0.05). The activated clotting time, determined 10 minutes after bolus injection of 250 IU (group M) or 375 IU heparin (all other groups), was 529 +/- 109 seconds in group C, greater than 1000 seconds in group M, 483 +/- 99 seconds in group Hsc, and 406 +/- 63 seconds in group Hiv (p less than 0.05). Heparin consumption during cardiopulmonary bypass varied between 4.6 +/- 1.4 IU/kg.min (group Hiv) and 2.6 +/- 0.9 IU/kg.min (group M) (p less than 0.05). Despite this increased heparin consumption, the patients who had received heparin before operation demonstrated increased activation of coagulation at the end of cardiopulmonary bypass (thrombin-antithrombin III complex, 19 +/- 4.1 ng/ml in group M and 61 +/- 7 ng/ml in group Hsc, p less than 0.05; cross-linked fibrin fragments, 257 +/- 92 ng/ml in group M and 875 +/- 152 ng/ml in group Hiv, p less than 0.05). Increased platelet activation was also found in patients with preoperative heparin therapy (beta-thromboglobulin at the end of cardiopulmonary bypass was 585 +/- 88 ng/ml in group M versus 1341 +/- 190 ng/ml in group Hsc, p less than 0.05). Drainage from the chest tube 24 hours after operation was 815 +/- 305 ml in group C, 644 +/- 238 ml in group M, 1133 +/- 503 ml in group Hsc, and 950 +/- 505 ml in group Hiv (p less than 0.05 for group M versus group Hsc). This study suggests that patients who receive heparin therapy before operation face a high risk of insufficient anticoagulation during cardiopulmonary bypass if standard heparin doses are used. Therefore, for patients who receive preoperative heparin therapy, a larger (500 IU/kg) initial bolus of heparin is recommended before cardiopulmonary bypass. On the other hand, patients who undergo preoperative treatment with phenprocoumon receive sufficient anticoagulative effect with a heparin bolus of 250 IU/kg.(ABSTRACT TRUNCATED AT 400 WORDS)     

Preoperative and postoperative right ventricular function during exercise in patients with mitral stenosis.

To elucidate the effects of mitral valve surgery on right ventricular function in 11 patients with mitral stenosis, pre- and postoperative right ventricular function were quantified using gated equilibrium blood pool radionuclide ventriculography at rest and during exercise. The preoperative right ventricular ejection fraction was 39 +/- 4% at rest and 36 +/- 9% during exercise, which during exercise was lower than control values (51 +/- 5%) (p < 0.01). When the preoperative right ventricular ejection fraction was lower during exercise than at rest, postoperative right ventricular ejection fraction during exercise was lower than normal values (42 +/- 3% versus 51 +/- 5%) (p < 0.01). When the preoperative right ventricular ejection fraction did not decrease during exercise, the postoperative right ventricular ejection fraction was within normal limits during exercise (54 +/- 5%). In addition, postoperative right ventricular ejection fraction during exercise increased to normal values in patients whose preoperative right ventricular ejection fraction during exercise had been 40% or higher. Preoperative peak ejection rate was -1.81 +/- 0.19 EDV/sec at rest and -1.72 +/- 0.39 EDV/sec during exercise, which during exercise was lower than control values (-2.44 +/- 0.53 EDV/sec) (p < 0.01). Postoperatively, peak ejection rate during exercise (-2.50 +/- 0.37 EDV/sec) increased (p < 0.05) to normal levels. Preoperative peak filling rate was 1.61 +/- 0.47 EDV/sec at rest and 1.88 +/- 0.54 EDV/sec during exercise, which during exercise was lower than control values (2.58 +/- 0.62 EDV/sec) (p < 0.01). Postoperatively, peak filling rate during exercise (2.82 +/- 0.62 EDV/sec) increased (p < 0.05) to normal values in all patients. Preoperative changes in both right ventricular ejection fraction and peak ejection rate from rest to exercise inversely correlated with the preoperative pulmonary vascular resistance at rest (right ventricular ejection fraction, r = -0.79, p < 0.005; and peak ejection rate, r = -0.67, p < 0.05). In conclusion, right ventricular systolic function improved in about half of the patients with mitral stenosis, and diastolic function improved in all patients during exercise following surgery. When the preoperative pulmonary vascular resistance was elevated, the right ventricular systolic dysfunction persisted.     

Levels of plasma cyclic AMP in cardiac surgery

The actions of hormones such as catecholamines, vasopressin and growth hormones are mediated by a common intracellular second messenger, cyclic AMP (adenosine 3',5'-monophosphate). The effects of cardiac surgery on plasma cyclic AMP were studied in 32 adults patients with aorta-coronary bypass or with valvular disease. Blood specimens were obtained before operation, at the beginning and at the end of the cardiopulmonary bypass, 1, 3, 6, 9, 12, 24, 48, 72, 168 hours after surgery. The plasma cyclic AMP level during cardiac operation was elevated above the preoperative level. High levels of plasma cyclic AMP were found both in the aorta-coronary bypass and in the valvular disease immediately after the end of cardiopulmonary bypass. The plasma cyclic AMP level in patients undergoing aorta-coronary bypass with aortic clamping time more than 60 minutes was 38.6 +/- 11.7 pmol/ml, compared to 25.6 +/- 6.6 pmol/ml with aortic clamping time less than 60 minutes immediately after the end of cardiopulmonary bypass. In patients undergoing valve replacement and/or commissurotomy with aortic clamping time more than 60 minutes, the plasma cyclic AMP level immediately after the end of cardiopulmonary bypass was 113 +/- 63.3 pmol/ml, compared to 45.4 +/- 10.3 pmol/ml with aortic clamping time less than 60 minutes (p less than 0.01, Student's t test). During 24 hours after cardiac surgery, the plasma cyclic AMP concentration returned to normal range. It is considered that the plasma cyclic AMP level reflects the risk of cardiac surgery in response to homeostatic derangement.     

Hemodynamic changes and ventricular function before and after Fontan procedure for univentricular heart

Ventricular function and hemodynamic parameters before and after Fontan operation were studied in patients with univentricular heart (UVH) of left ventricular (LV) type (9 cases, ages: 6-66, mean 13 years) and right ventricular (RV) type (13 cases, ages: 6-17, mean 9 years) without atrioventricular valve regurgitation. The preoperative ejection fraction (EF) was poor and only 44% of LV type and 23% of RV type met the Choussat's criterion (EF greater than or equal to 60%). There were 2 hospital deaths each in LV type and in RV type, but their causes could not be attributed to preoperative parameters of ventricular function. In survivors, the EF reduced from 62.9 +/- 7.0% before Fontan procedure to 43.4 +/- 12.6% after the procedure in LV type (p less than .05) and from 54.5 +/- 7.0% to 47.0 +/- 9.0% in RV type (p less than .01), although the ventricular end-diastolic pressure (EDP) also reduced from 12.7 +/- 2.7 mmHg before to 6.6 +/- 1.9 mmHg after the operation in LV type (p less than .05) and 10.4 +/- 2.6 mmHg to 5.5 +/- 2.4 mmHg in RV type (p less than .05). the ventricular end-diastolic volume (EDV) also reduced from 185 +/- 35% to 126 +/- 58% of expected normal volume in LV type (p less than .05) and 173 +/- 28% to 99 +/- 18% of expected normal volume in RV type (p less than .01).(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of pre-existing left ventricular hypertrophy on ventricular dysfunction and remodeling following myocardial infarction in rats.

BACKGROUND: Myocardial hypertrophy is a characteristic component of left ventricular (LV) remodeling that may, at least initially, have a beneficial effect on LV function following myocardial infarction (MI). In the present study, we examine the effects of pre-existing left ventricular hypertrophy (LVH) on LV function and chamber enlargement following MI in inbred Lewis rats. METHODS: The one-kidney, one-clip model (1K1C) of hypertension was used to produce LVH. Four weeks after 1K1C, rats were randomized to left anterior descending coronary artery ligation (LVH + MI group, n = 8) or sham ligation (LVH group, n = 11). Another group of rats underwent sham 1K1C. Four weeks later, they were randomized to coronary ligation (MI group, n = 12) or sham ligation (Sham group, n = 12). LV end-diastolic pressure (EDP, mm Hg), end-diastolic volume (EDV, ml), end-systolic volume (ESV, ml) and ejection fraction (EF) (determined by angiography) were measured in all groups 2 months after MI. RESULTS: LV EDP was 20 +/- 2 mm Hg in the LVH + MI group compared with 9 +/- 1 mm Hg in the MI group (p < 0.05). LV EDV and ESV were significantly greater with LVH + MI than with MI alone (EDV 0.90 +/- 0.03 vs 0.75 +/- 0.02 ml; ESV 0.68 +/- 0.02 vs 0.50 +/- 0.03 ml; p < 0.05). Pre-existing LVH resulted in a greater reduction in EF following MI (25 +/- 2% for LVH + MI vs 34 +/- 2% for MI alone; p < 0.05). CONCLUSIONS: Pre-existing LVH is an important determinant of progressive LV dysfunction and remodeling following MI in Lewis inbred rats.     

Late postoperative left ventricular function and ventricular hypertrophy after prosthetic valve replacement for aortic regurgitation]

Forty-two of 50 patients, who had undergone aortic valve replacement for acquired aortic regurgitation from Jan 1979 to Dec 1985, received late postoperative cardiac catheterization two years after operation. Their ages ranged between 10 and 69 years old (mean +/- S.D., 45.8 +/- 12.2 y.o.) and 37 men and 13 women were included. Postoperative left ventricular end-diastolic volume (LVEDV), end-systolic volume (LVESV) and left ventricular mass (LVM) decreased significantly compared to preoperative levels, respectively (p less than 0.001). Both postoperative left ventricular end-systolic stress/end-systolic volume ratio (LVESS/ESVI) and tension volume ejection fraction (TVEF) increased significantly (p less than 0.01) compared to preoperative levels. Positive correlations were recognized between preoperative and postoperative values in LVESV, LVM, LVESS/ESVI, TVEF and LVEF. In the patients who had showed preoperative values of LVEDVI less than 180 ml/m2, LVESVI less than 90 ml/m2 and LVEF more than 0.52, their postoperative values were expected to be normal. There were also negative correlations between LVESVI and LVEF, and between LVM and contractile properties. Nineteen patients, who had recovered normal ventricular volumes at the time of postoperative cardiac catheterization, showed normal LV dimensions and % fractional shortening between five and ten years after operation. These results demonstrate the limitation of recovery in LVM and contractile properties in spite of normalization in ventricular volume and ejection performance.     

Effect of aortocoronary bypass surgery on left ventricular function and coronary sinus blood flow in patients with severe left ventricular dysfunction

Left ventricular function and coronary sinus blood flow were evaluated in 7 patients with severe left ventricular dysfunction at rest before and after aortocoronary bypass surgery, and during exercise after surgery. Same evaluations were performed in 8 normal subject (G-C). Cardiac index (CI) at rest (2.09 +/- 0.55 l/min/m2) significantly increased after operation (2.94 +/- 0.59 l/min/m2) (p less than 0.02). There was no difference between CI during exercise after operation (5.94 +/- 1.51 l/min/m2) and that in G-C. Left ventricular end-diastolic pressure (LVEDP) at rest before operation (16 +/- 8 mmHg) was significantly higher than that in G-C (p less than 0.05). This difference disappeared after operation. LVEDP during exercise after operation (25 +/- 10 mmHg) was significantly higher than that in G-C (p less than 0.01). Coronary sinus blood flow (CSF) at rest (73 +/- 15 ml/min) significantly increased after operation (123 +/- 44 ml/min) (p less than 0.02). There was no difference between CSF during exercise after operation (282 +/- 99 ml/min) and that in G-C. These data indicated that the aortocoronary bypass surgery was effective on left ventricular function and coronary sinus blood flow in patients with severe left ventricular dysfunction.     

Long-term results of coronary artery bypass grafting procedure in the presence of left ventricular dysfunction and hibernating myocardium.

OBJECTIVE: Long-term left ventricular (LV) performance and patient outcome after coronary artery bypass grafting (CABG) procedure in the presence of depressed LV function and hibernating myocardium (HM) have been poorly determined. Therefore, we prospectively evaluated patients undergoing CABG with severe LV dysfunction and HM to elucidate postoperative prognosis. METHODS: We enrolled 120 consecutive patients undergoing CABG with severe LV dysfunction and HM as assessed by dobutamine echocardiography and by rest-redistribution radionuclide (Thallium-201) study. Mean patient age was 60+/-9 years (range 31-77 years). Mean preoperative LVEF was 28%+/-9 (range 10-40%). All patients underwent echocardiographic study to assess LV recovery of function intraoperatively, prior to hospital discharge, at 3 months, at 1 year, and yearly during the follow-up. Univariate and multivariate analysis were performed to to evaluate predictors of postoperative survival. RESULTS: There were 2 hospital (1.6%) and 15 late (12.5%) deaths, mainly for heart failure, leading to an actuarial survival of 80+/-6% and 60+/-9% at 5 and 8 years, respectively. LVEF significantly improved perioperatively (from 28+/-9% to 40+/-2%, P<0.01). Increase in LVEF, however, was gradually offset over the time (EF of 33+/-9%, 32+/-8%, and 30+/-9% at 3 months, and 12 months, and 8 years after surgery, respectively). Furthermore, patients who experienced limited LV functional recovery perioperatively had a more remarkable decline of LVEF thereafter, and suffered from recurrence of heart failure symptoms (freedom from heart failure 82+/-5% and 60+/-8% at 4 and 8 years respectively). Advanced preoperative NYHA Class, and age were independent risks factors for reduced postoperative survival. Preoperative angina and use of arterial conduits apparently did not influence patient morbidity and mortality at long term. CONCLUSION: CABG procedure in the presence of HM enhances LV recovery of function and has a favourable prognosis. Functional benefit of the left ventricle, however, appears to be time-limited, despite remarkable improvement in patient functional capacity. Advanced preoperative heart failure, minimal perioperative improvement of LVEF, and age account for a poor long-term prognosis.     

Current approaches to pulmonary regurgitation

Objective: To evaluate the effects on ventricular function and volumes following right ventricular outflow tract reconstruction (RVOTR) with pulmonary homograft replacement (PVR) and percutaneous pulmonary valve implantation (PPVI) for predominant pulmonary regurgitation. This study was not intended to compare the two approaches. Methods: We prospectively examined 25 patients (mean age 21+/-13 years, 96% tetralogy of Fallot, 1/25 with conduit dysfunction) who had PVR with RVOTR for severe pulmonary regurgitation (PR), and 11 patients (mean age 20+/-9 years, 64% tetralogy of Fallot, 9/11 with conduit dysfunction) who underwent PPVI for predominant PR. Mean age at primary repair in both groups was 4.3+/-6.6 years. Magnetic resonance imaging was performed prior to, and 1 year following, interventions. Results: Before procedure, NYHA classification was similar in both groups 2.1+/-0.5. Following interventions, there was a significant reduction in RV volumes in both groups. In the surgical (PVR) group, RV end-diastolic volume (EDV) decreased from 151+/-49 to 97+/-32ml/m(2) (p<0.0001) whereas end-systolic volume (ESV) decreased from 80+/-43 to 46+/-23ml/m(2) (p<0.0001). In the PPVI group, RV EDV decreased from 106+/-27 to 89+/-25ml/m(2) (p=0.002) and RV ESV from 49+/-20 to 40+/-16ml/m(2) (p=0.034). Both groups had a significant improvement in RV (63+/-20 to 72+/-16ml/beat, p=0.003 (PVR group), 53+/-14 to 67+/-16ml/beat, p=0.030 (PPVI group)) and LV effective stroke volume (61+/-18 to 73+/-16ml/beat, p=0.001 (PVR group); 59+/-24 to 75+/-16ml/beat, p=0.009 (PPVI group)). Conclusions: Following either PVR with RVOTR or PPVI, there was a significant reduction in RV volumes and an improvement in RV function. Importantly, in both groups, LV effective SV increased, and this may be the parameter to judge the benefit of the procedure. These results also support PPVI as an extra dimension in complex RVOT management.     

Radionuclide Assessment of Left Ventricular Function in Patients Requiring Intraoperative Balloon Pump Assistance

Twenty-three surviving patients who were weaned from cardiopulmonary bypass with intraaortic balloon pump assistance returned for follow-up radionuclide left ventricular (LV) function and thallium 201 perfusion studies at a mean of 23 ± 3 months following operation. It was found that despite profound intraoperative myocardial depression requiring intraaortic balloon assistance, 13 patients had no change (within 10%) in the resting LV ejection fraction compared with the preoperative measurement. Among all 23 patients, there was no difference between mean (± standard error of the mean) preoperative and postoperative resting LV ejection fraction (48 ± 4 vs 46 ± 4%, p = not significant [NS]). Only 11 patients had perioperative myocardial infarction documented by new Q waves in the electrocardiogram, by elevation of creatine kinase–MB fraction, or by defects on thallium 201 imaging not explained by documented myocardial infarction before operation. Overall, postoperative resting LV ejection fraction was not different from the preoperative value in patients with perioperative myocardial infarction (44 ± 7 vs 47 ± 5%, p = NS). Postoperative resting LV ejection fraction rose by ≥ 10% compared with preoperative values in 4 patients (3 with aortic valve replacement), remained within the 10% limit in 9 patients, and fell by ≥ 10% in 10 patients (7 with perioperative myocardial infarction). Only 4 out of 16 patients studied at follow-up with exercise radionuclide studies demonstrated a normal LV response to exercise (≥ 5% increase in LV ejection fraction).Thus, among survivors requiring intraaortic balloon pump assistance for weaning from cardiopulmonary bypass, LV performance at rest is frequently preserved. In addition, 11 of the 23 patients had evidence of perioperative myocardial infarction, indicating a component of reversible intraoperative LV dysfunction.     

Does On‐Pump/Beating‐Heart Coronary Artery Bypass Grafting Offer Better Outcome in End‐Stage Coronary Artery Disease Patients?

OBJECTIVES: The purpose of our study was to evaluate in a cohort of end-stage coronary artery disease (ESCAD) patients the effects of on-pump/beating-heart versus conventional coronary artery bypass grafting (CABG) requiring cardioplegic arrest. We report early and midterm survival, morbidity, and improvement of left ventricular (LV) function. METHODS: Between January 1992 and October 1999, 107 (Group I) ESCAD patients underwent on-pump/beating-heart surgery and 191 (Group II) ESCAD patients underwent conventional CABG requiring cardioplegic arrest. Mean age in Group I was 65.8 +/- 6.5 years (58-79 years); New York Heart Association (NYHA) and Canadian Cardiovascular Society (CCS) classifications were 3.2 +/- 0.4 and 3.3 +/- 0.5, respectively. LV ejection fraction (LVEF) was 24.8% +/- 4%, LV end diastolic pressure (LVEDP) was 28.2 +/- 3.8 mmHg, and LV end diastolic diameter (LVEDD) was 69.6 +/- 4.6 mm. Mean age in Group II was 64.1 +/- 5 years (57-76 years), NYHA class was 3 +/- 0.6, CCS class was 3.4 +/- 0.4, LVEF was 26.2% +/- 4.3%, LVEDP was 27.2 +/- 3.4 mmHg, and LVED was 68 +/- 4.2 mm. RESULTS: Preoperatively, Group I patients versus Group II patients had a markedly depressed LV function (LVEF, p = 0.006; LVEDP, p = 0.02; LVEDD, p = 0.003; and NYHA class, p = 0.002), older age (p = 0.012), and higher incidences of multiple acute myocardial infarction (AMI; p = 0.004), cardiovascular disease (CVD; p = 0.008), and chronic renal failure (CRH, p = 0.002). Cardiopulmonary bypass (CPB) time was longer in Group II patients (p = 0.028). The mean distal anastomosis per patient was similar between groups (p = NS). Operative mortality between Groups I and II was 7 (6.5%) and 19 (10%), respectively (p = NS). Perioperative AMI (p = 0.034), low cardiac output syndrome (LCOS; p = 0.011), necessity for ultrafiltration (p = 0.017), and bleeding (p = 0.012) were higher in Group II. Improvement of LV function within 3 months after the surgical procedure was markedly higher in Group I, demonstrated by increased LVEF (p = 0.035), lower LVEDP (p = 0.027), and LVEDD (p = 0.001) versus the preoperative data in Group II. The actuarial survivals at 1, 3, and 5 years were 95%, 86%, and 73% in Group I and 95%, 84%, and 72% in Group II (p = NS). CONCLUSIONS: ESCAD patients with bypassable vessels to two or more regions of reversible ischemia can undergo safe CABG with acceptable hospital survival and mortality and morbidity. In higher risk ESCAD patients, who may poorly tolerate cardioplegic arrest, on-pump/beating-heart CABG may be an acceptable alternative associated with lower postoperative mortality and morbidity. Such a technique offers better myocardial and renal protection associated with lower postoperative complications.     

Early extubation after coronary artery bypass surgery: effects on oxygen flux and haemodynamic variables.

The effect of extubation within the first postoperative hour was evaluated in 13 patients (mean +/- SD age 59 +/- 6 years) undergoing elective coronary artery bypass surgery without active systemic hypothermia. The mean cardiopulmonary bypass time was 50 +/- 14 minutes. Postoperative improvements in cardiac index and oxygen uptake (from 2.0 +/- 0.4 l/min/m2 and 144 +/- 26 ml/min postinduction to 2.88 +/- 0.76 l/min/m2 and 229 +/- 104 ml/min, p less than 0.01) were maintained following extubation. Lower postoperative systemic and pulmonary vascular resistances (p less than 0.01) did not change to a significant extent following extubation. Despite a two-fold rise in the intrapulmonary shunt (Qs/Qt) following surgery (18.5 +/- 9.7% vs 9.6 +/- 3.2% before surgery) the immediate post-extubation value was similar (18.8 +/- 8.2%) and all patients were discharged from the cardiac recovery area within 16 hours without complication. Extubation within the first postoperative hour is a safe procedure following elective coronary artery surgery with short bypass times where sustained hypothermia less than 32 degrees C is avoided.     

Beneficial effect of aspirin on renal function in patients with renal insufficiency postcardiac surgery

AIM: Renal function is one of the most important prognostic factors following cardiac surgery. Whether aspirin affects cardiopulmonary bypass related renal injury is investigated in this study. METHODS: Ninety-four patients with impaired renal function (creatinine = or >1.5 mg/dl) undergoing coronary artery bypass grafting (CABG) were categorized into 2 groups according to aspirin administration before surgery. Serum creatinine, urinary output and creatinine clearance along with other perioperative factors were compared between the 2 groups prior to surgery, 24 hours and 48 hours following cardiopulmonary bypass. RESULTS: Creatinine levels increased significantly in the second postoperative day only in the non-aspirin (control) group (3.7+/-1.6 vs 2.9+/-1.7 mg/dl, p=0.03). Aspirin (study) group had lower creatinine levels in day 1 (p=0.03) and day 2 (p=0.001). Furthermore, in the study group creatinine clearance was higher in day 1 (34.3+/-14.3 vs 30.9+/-13.1 ml/min, p=0.01) and in day 2 (32.6+/-13.8 vs 26.4+/-9.8 ml, p<0.0001). Creatinine levels at discharge were elevated compared to the preoperative levels in the control group (p=0.01). However, the study group had lower creatinine levels at discharge (2.6+/-1.4 vs 3.8+/-1.6 mg/dl, p<0.0001). Urinary output was higher in the study group in the first postoperative day compared to the control group (p=0.01). Postoperative bleeding was slightly increased in the study group compared to the control group (760+/-230 ml vs 530+/-210 ml, p=0.01). CONCLUSIONS: Continuation of aspirin administration until the day of surgery may have a protective effect against renal injury resulting from cardiopulmonary bypass, with only a negligible increase in bleeding. Possible explanations for this effect are antiplatelet activity of aspirin during cardiopulmonary bypass causing inhibition of vasoconstrictive agents like thromboxane, and improvement of renal perfusion by reducing blood viscosity.     

Effects of pulsatile perfusion on plasma catecholamine levels and hemodynamics during and after cardiac operations with cardiopulmonary bypass

Thirty patients scheduled for elective coronary artery bypass grafting were studied in two groups. Group A had standard cardiopulmonary bypass with nonpulsatile perfusion and group B had pulsatile perfusion. Measurements of plasma epinephrine, norepinephrine, granulocyte elastase, and hemodynamic parameters including mean arterial pressure total peripheral resistance, cardiac index, and pulmonary capillary wedge pressure were made before and after anesthesia induction, after surgical incision, during cardiopulmonary bypass, and 2, 4, and 24 hours after the operation. The venous compliance of the total body venous bed was measured at the end of the operation. In all patients the total net fluid balance was determined during bypass and in the postoperative period. In both groups plasma catecholamine levels increased 5 minutes after institution of bypass (epinephrine 176 +/- 56 to 611 +/- 108 pg/ml and norepinephrine 231 +/- 48 to 518 +/- 100 pg/ml in group A; epinephrine 168 +/- 40 to 444 +/- 100 pg/ml and norepinephrine 162 +/- 44 to 267 +/- 52 pg/ml in group B). The maximum catecholamine level was measured between the end of bypass and 2 hours after the end of bypass (epinephrine 1489 +/- 169 pg/ml and norepinephrine 1542 +/- 108 pg/ml in group A; epinephrine 990 +/- 134 pg/ml and norepinephrine 934 +/- 197 pg/ml in group B). During the same period mean arterial pressure and total peripheral resistance were also significantly higher in group A than in group B mean arterial pressure, 61.4 +/- 3 versus 53.6 +/- 3, p less than 0.06; total peripheral resistance, 1055 +/- 60 versus 899 +/- 45, p less than 0.01). The venous compliance was significantly higher in group A than in group B (2.4 +/- 0.3 versus 1.2 +/- 0.3 ml/mm Hg/kg body weight). The intraoperative and perioperative net fluid balance were significantly higher in group A than in group B (p less than 0.005). The average postoperative tracheal intubation time was also significantly longer in group A than in group B (4.6 +/- 1.2 hours versus 2.7 +/- 0.8 hours, p less than 0.001). No significant difference was detected in either hemoglobin or plasma free hemoglobin content between the two groups postoperatively. The results suggest that pulsatile perfusion, when compared with nonpulsatile perfusion, can attenuate the catecholamine stress response to cardiopulmonary bypass, reduce the fluid overloading of patients, and improve the postoperative recovery period as evaluated by tracheal intubation time.     

The influence of pulmonary regurgitation on left ventricular function after repair of tetralogy of Fallot

The influence of right ventricular (RV) volume overload by pulmonary regurgitation (PR) on left ventricular (LV) function was evaluated postoperatively in 23 patients with tetralogy of Fallot (TF). The age at operation was 3.1 +/- 1.7 (mean +/- SD) years. The age at postoperative study was 5.9 +/- 2.0 years. We determined RV end-diastolic volume (%RVEDV), RV ejection fraction (EF), %LVEDV, LV end-systolic volume (%LVESV), LVEF, and LV end-systolic stress (ESS)/%LVESV. Patients were divided into 2 groups on the basis of presence or absence of RV volume overload by PR as follows: The %RVEDV (175 +/- 23%) of group 1 (n = 10) was 150% greater than normal RVEDV. Group 2 (n = 13) had normal %RVEDV (108 +/- 23%). Preoperatively, there had been no differences in hemoglobin, %RVEDV, RVEF, %LVEDV, LVEF, and in the ratio of average cross-sectional area of the left and right pulmonary arteries to cross-sectional area of the normal right pulmonary artery between the 2 groups. Moreover, there were no differences in age at repair, or during postoperative study, nor in the postoperative ratio of RV to LV systolic pressure between the 2 groups. RVEF was significantly less in group 1 than in group 2 (0.53 +/- 0.05 vs 0.58 +/- 0.05, p less than 0.05). %LVEDV and %LVESV in group 1, 138 +/- 10% and 171 +/- 30% respectively, were significantly greater than those in group 2, 116 +/- 11% and 133 +/- 20% respectively (p less than 0.001 in %LVEDV and p less than 0.01 in %LVESV).(ABSTRACT TRUNCATED AT 250 WORDS)     

Improvement of severely reduced left ventricular function after surgical revascularization in patients with preoperative myocardial infarction.

In recent years, two pathophysiological conditions--stunned and hibernating myocardium--have been described showing how function may be depressed in myocardium that remains viable. The aims of the present study were postoperative assessment of LV function at rest and during exercise after CABG in patients with established previous myocardial infarction and impaired preoperative LV function and evaluation of preliminary experience with positron emission tomography (PET) in the preoperative identification of reversible ischaemic myocardium and its predictivity in postoperative functional improvement. We studied 23 patients with preoperative LV function under 45%. Echocardiography and complete heart catheter were performed pre- and postoperatively. PET was performed in all patients preoperatively. In 21 patients with patent grafts, CABG significantly improved systolic and diastolic function during exercise and at rest. EF improved from 34% +/- 14% to 52% +/- 11% at rest and from 31% +/- 14% to 58% +/- 13% during exercise (P less than 0.01). Time constant of diastolic relaxation was significantly reduced after revascularization. In 2 patients with pathological findings on postoperative coronarangiography, EF remained unchanged. Both global and regional contractility improved following surgery. Regional analysis indicated that improved EF at rest occurred in regions developing ischaemia during exercise before CABG and in regions showing typical mismatch in 82Rubidium-2-fluoro-2-desoxyglucose suggesting the presence of hibernating myocardium.(ABSTRACT TRUNCATED AT 250 WORDS)     

A reappraisal of surgical intervention for acute myocardial infarction

Eighty-three patients underwent coronary artery bypass during acute evolving myocardial infarction 6.8 +/- 2.8 hours after the onset of symptoms. Linear discriminant analysis of preoperative variables identified predictors of mortality with an accuracy of 84%. Significant predictors in decreasing order of importance were cardiogenic shock, age over 65 years, left ventricular ejection fraction less than or equal to 0.30, cardiac index less than or equal to 2.0 L/min/m2, and absent collateral flow. Time to reperfusion did not influence outcome nor did the infarct-related artery. Hospital mortality was 15.6% (13/83). Among 51 low-risk patients under 65 years of age without cardiogenic shock, there were three deaths (5.9%). Follow-up angiography was performed in 21 patients. The graft patency rate was 94%. Left ventricular ejection fraction improved from 0.39 +/- 0.10 to 0.49 +/- 0.11 (p less than 0.05). Left ventricular end-systolic volume decreased from 53.2 +/- 19.3 ml/m2 to 41.4 +/- 16.8 ml/m2 (p less than 0.05), and end-diastolic volume remained unchanged: 86.2 +/- 21.2 ml/m2 before operation and 78.7 +/- 24.0 ml/m2 after operation (no significant difference). Regional ejection fraction of the infarct area, determined by the centerline method, increased 0.23 +/- 0.15. In contrast, among 215 patients treated by nonsurgical reperfusion (intracoronary thrombolysis or angioplasty, or both), mortality was 13.5%. In this group, reperfusion was successful in 144 patients (67%) and 89 underwent follow-up angiography. Persistent patency of the infarct artery was demonstrated in 73 (82%). Ejection fraction increased from 0.45 +/- 0.10 to 0.50 +/- 0.15 (p less than 0.05). We conclude that preoperative variables enable identification of patients with evolving acute myocardial infarction in whom coronary artery bypass is associated with low operative mortality and improved ventricular performance.     

Surgery for Chronic Left Ventricular Aneurysm: Benefits and side effects

Seventy patients who underwent elective resection of symptomatic postinfarction apico-anterior left ventricular (LV) aneurysm with or without coronary revascularization are reviewed. The early (?30 day) mortality was 5.7%. Mural thrombosis occurred in 29 cases (41.4%), unrelated to the degree of preoperative LV impairment and predictable from preoperative LV angiography in only seven cases. The response to surgery comprised significant overall improvement of global LV ejection fraction (LVEF) during rest and of all variables in stress testing. This LVEF recovery correlated significantly with that of peak ejections rate, a variable of myocardial contractility. Contrastingly, right ventricular ejection fraction (RVEF) at rest decreased slightly but significantly without correlation to preoperative RVEF or LVEF. In comparisons between patients with congestive heart failure or angina at rest as dominant symptom, the former group showed greater depression of preoperative watt and LVEF but better postoperative recovery of these variables, while right ventricular deterioration was significant only in the latter. Postoperative recovery was best in patients with poor preoperative LV function (LVEF ? 20%), even when surgery comprised only aneurysmectomy in isolated but ungraftable LAD disease (5 cases). The observed RV deterioration may be ‘nonspecific', but it must be kept in mind as a side effect of the operation, as it detracts unpredictably from postoperative ventricular recovery. Patients with well preserved preoperative LVEF, small LV aneurysm and marginal expected postaneurysmectomy changes according to LaPlace's law are probably at risk, and surgery should then instead be directed towards preserving the remaining viable myocardium by direct revascularization.