Beneficial effects of ischemic preconditioning on right ventricular function after coronary artery bypass grafting

BACKGROUND: Preservation of right ventricular myocardium is unsatisfactory in patients with critical stenosis or occlusion of the right coronary artery. The aim of this study was to investigate whether ischemic preconditioning (IP) improved the recovery of right ventricular function after coronary artery bypass grafting. METHODS: Forty patients with three-vessel disease who had coronary artery bypass grafting were randomly assigned to the IP group (n = 20) or control group (n = 20). In the IP group, two cycles of two minutes of ischemia after three minutes of reperfusion were given before cross-clamping. Hemodynamic data were collected. Right ventricular ejection fraction was measured by thermodilution. RESULTS: Right ventricular ejection fraction and right ventricular systolic volume index were decreased post-operatively (lowest value at 6 hours postoperatively). The changes in right ventricular ejection fraction were significantly milder in the IP group postoperatively (p = 0.012). The decrease in right ventricular systolic volume index postoperatively was also less in IP patients (p = 0.002). Fewer inotropic drugs were used in the IP group compared with controls. CONCLUSIONS: Ischemic preconditioning had a myocardial protective effect on recovery of right ventricular contractility in patients who had coronary artery bypass grafting.     

Intraoperative assessment of right ventricular volume and function

Objective: Right ventricular function is an important aspect of global cardiac performance which affects patients' outcome after cardiac surgery. Due to its geometrical complexity, the assessment of right ventricular function is still a very difficult task. Aim of this study was to investigate the value of a new technique for intraoperative assessment of right ventricle based on transesophageal 3D-echocardiography, and to compare it to volumetric thermodilution by using a new generation of fast response thermistor pulmonary artery catheters. Methods: Twenty-five patients with coronary artery disease underwent 68 intraoperative measurements by 3D-echocardiography and thermodilution simultaneously. Following parameters were analysed: right ventricular end-diastolic volume (RVEDV), end-systolic volume (RVESV) and ejection fraction (RVEF). Pulmonary, systemic and central venous pressures were simultaneously recorded. Segmentation of right ventricular volumes were obtained by the ‘Coons-Patches’ technique, which was implemented into the EchoAnalyzer^®, a multitask system developed at our institution for three-dimensional functional and structural measurements. Results: Right ventricular volumes obtained by 3D-echocardiography did not show significant correlations to those obtained by thermodilution. Volumetric thermodilution systematically overestimates right ventricular volumes. Significant correlations were found between RVEF measured by 3D-echocardiography and those obtained by thermodilution (r=0. 93; y=0.2+0.80x; SEE=0.03; P<0.01). Bland–Altmann analysis showed that thermodilution systematically underestimates RVEF. The bias for measuring RVEF was +15.6% with a precision of ±4.3%. The patients were divided into two groups according to left ventricular function. The group of patients with impaired function showed significantly lower right ventricular ejection fraction (44.1±4.6 vs. 55.1±3.9%; P<0.01). Conclusions: Three-dimensional echocardiography provides a useful non-invasive tool for intraoperative and serial assessment of right ventricular function. This new technique, which overcomes the limitations of previous methods, may offer key insights into management and outcome of patients with severe impairment of cardiac function.     

Atrial natriuretic peptide and N-terminal atrial natriuretic peptide in plasma reflect right ventricular volumes following coronary artery surgery

Background: Atrial natriuretic peptide (ANP) and the more stable N-terminal fragment (N-ANP) of prohormone are peptides, released in equimolar amounts from cardiac myocytes in response to atrial stretch or ventricular overload and myocardial ischaemia. Protection of the right ventricular (RV) myocardium during ischaemia in cardiac surgery is difficult, especially in patients with severe right coronary artery (RCA) disease. This prospective study was designed to ascertain a possible relationship between changes in plasma ANP/N-ANP concentration and RV function in RCA-diseased patients.
Methods: Plasma ANP and N-ANP concentrations and RV function, measured by fast-response thermodilution, were determined serially in 15 patients with total RCA stenosis and in another 15 with no significant RCA disease (controls) before, during and after coronary artery surgery.
Results: The RV ejection fraction was lower and the RV end-systolic volume index higher in the RCA-diseased patients than in the controls ( P < 0.05) on the second postoperative day, and both ANP and N-ANP were higher in the RCA patients ( P < 0.05) from 6 h after cardiopulmonary bypass till the second postoperative day. At the same time the changes in N-ANP concentrations from the levels before induction of anaesthesia correlated with RV ejection fraction and RV volume indexes, but not with heart rate or parameters indirectly reflecting left-sided loading. Right atrial pressure did not differ between the groups nor did it increase significantly during the study.
Conclusions: The relationships found between N-ANP and RV volume indexes and RV ejection fraction suggest ventricular expression of ANP: ANP release may be stimulated by RV distension, the more so the poorer the RV function.     

Usefulness of right ventricular indices in early diagnosis of cardiac tamponade.

Early diagnosis of postoperative cardiac tamponade is impeded by its clinical similarity to left ventricular failure. Moreover, the hemodynamic changes necessary to diagnose cardiac tamponade are detected by conventional monitoring technique only after clinical compromise. Early signs of cardiac tamponade and left ventricular failure were studied with emphasis on right ventricular function in anesthetized dogs. One group (n = 20) had cardiac tamponade produced by incrementally increasing pericardial pressure (2 to 20 mm Hg), and another group (n = 20) had acute left ventricular failure produced by successive ligation of the anterior descending coronary artery at the lower, middle, and upper thirds. Besides standard hemodynamic measurements, right ventricular function was examined with a rapid-response thermodilution catheter. During cardiac tamponade, cardiac output, right ventricular ejection fraction, right ventricular stroke volume, and right ventricular end-diastolic volume were significantly decreased from baseline values after a pericardial pressure of 8 mm Hg or more (p less than 0.05). Right atrial and pulmonary arterial pressures were not significantly elevated until 14 and 20 mm Hg of pericardial pressure, respectively. Although cardiac function in the left ventricular failure group was reduced after each ligation, right ventricular ejection fraction remained unchanged. This study suggests that right ventricular indices may facilitate earlier diagnosis of cardiac tamponade with greater accuracy.     

Factors that exaggerate the deleterious effects of pulmonary insufficiency on the right ventricle after tetralogy repair. Surgical implications

Postoperative cardiac catheterization data of 74 patients with pulmonary insufficiency after tetralogy repair were analyzed. Two groups were identified: Group A, 26 patients with normal right ventricular function (ejection fraction 95% +/- 5.5%, end-systolic volume 110% +/- 17% of predicted normal) and Group B, 48 patients with right ventricular dysfunction (ejection fraction 80% +/- 18% [p less than 0.001], and end-systolic volume 218% +/- 75% of predicted normal [p less than 0.001]). There was no significant difference between the two groups with respect to frequency of previous palliative procedures, age at operative repair, operative techniques, methods of myocardial protection, and follow-up period. Right ventricular dysfunction in Group B was associated with significant distal pulmonary stenosis (right ventricle-pulmonary artery pressure gradient 28 +/- 13 torr in Group A versus 55 +/- 20 torr in Group B, p less than 0.001), moderate pulmonary regurgitation (regurgitant fraction 18% +/- 11% in Group A versus 32% +/- 10% in Group B, p less than 0.001), and large transannular outflow patch (ratio of patch diameter to descending aorta diameter 1.31 +/- 0.16 in Group A versus 2.50 +/- 0.28 in Group B, p less than 0.001). Pulmonary valve insertion was performed in 42 patients in Group B. Eighteen had subsequent cardiac catheterization. Right ventricular function recovered completely (end-systolic volume 122% +/- 24%, and ejection fraction 92% +/- 7% of predicted) in five of six patients (83%) who had valve insertion within the first 2 years after tetralogy repair. In contrast, right ventricular function remained abnormal in all 12 patients who had valve insertion later than 2 years after tetralogy repair (p less than 0.05). Patients with residual pulmonary stenosis and/or a large transannular outflow patch are at risk for the development of right ventricular dysfunction from pulmonary insufficiency after tetralogy repair. Early correction of these residual lesions and control of pulmonary insufficiency may prevent long-term deterioration in right ventricular function.     

Right ventricular function in patients with aortic stenosis undergoing aortic valve replacement.

The effects of aortic stenosis (AS) on right ventricular function during cardiac surgery are not fully understood. Forty patients undergoing aortic valve replacement with either a systolic transvalvular gradient of less than 100 mm Hg (82.1 +/- 5.5 mm Hg; group 1, n = 20) or greater than 120 mm Hg (131.1 +/- 6.9 mm Hg, group 2, n = 20) were investigated with regard to right ventricular function in the perioperative period. Right ventricular ejection fraction (RVEF), right ventricular end-systolic volume (RVESV), and right ventricular end-diastolic volume (RVEDV) were measured by means of the thermodilution technique. Before cardiopulmonary bypass (CPB), RVEF was significantly lower in group 2 patients (34% +/- 6%) than in group 1 (45% +/- 5%). After CPB, RVEF increased significantly in group 2 (28% +/- 4% to 49% +/- 5%), and no further differences were noted between the groups. In the patients with a higher systolic transvalvular gradient, RVEDV and RVESV were lower at the start of surgery, but increased after opening the pericardium. Cardiac index was also lower in these patients. Pericardiotomy resulted in a decrease in right ventricular end-systolic pressure (RVESP) only in the patients of group 2. In these patients more epinephrine was necessary to maintain stable hemodynamics during the post-bypass period. It is concluded that patients with AS are at risk of reduced right ventricular function when the systolic transvalvular pressure gradient is more than 120 mmHg. Knowledge of the complex interaction between the two sides of the heart may enable anesthesiologists to optimize management during the perioperative period.     

Effect of controlled mechanical ventilation without positive end-expiratory pressure on right ventricular function after coronary artery bypass graft surgery

To evaluate the changes in right ventricular function during controlled mechanical ventilation (CMV) without positive end-expiratory pressure (PEEP) and during spontaneous breathing, we compared right ventricular ejection fraction (RVEF), right ventricular end-diastolic volume index (RVEDVI), and right ventricular end-systolic volume index (RVEDVI) using a thermodilution technique after coronary artery bypass graft surgery. Patients were divided into two groups on the basis of changes in RVEDVI from CMV to spontaneous breathing: group U (n = 6) consisted of patients whose RVEDVI increased during spontaneous breathing compared with mechanical ventilation, group D (n = 3) consisted of patients whose RVEDVI decreased during spontaneous breathing compared with mechanical ventilation. PVRI values during CMV in group D were significantly larger than those in group U. Patients in group U showed no increase in RVEDVI, or decrease in RVEF during CMV without PEEP. However, the remaining 3 patients in group D showed an increase in RVEDVI and a decrease in RVEF during CMV. Mean PAP, RAP, RV systolic pressure, RV end-diastolic pressure, PWP, HR, and mean arterial pressure in both groups were comparable, and showed no significant difference at each of the measured points by 24hrs postoperatively. Then, RVEF, RVEDVI and RVESVI measured by thermodilution technique is useful in evaluating ventricular function at bedside in ICU.(Mitsuhata H, Enzan K, Matsumoto S, et al.: Effect of controlled mechanical ventilation without positive end-expiratory pressure on right ventricular function after coronary artery bypass graft surgery. J Anesth 5: 363–369, 1991)     

The effect of incremental positive end-expiratory pressure on right ventricular hemodynamics and ejection fraction

The effects of incremental positive end-expiratory pressure (PEEP) on right ventricular (RV) function were evaluated in 36 (n = 36) ventilated patients. Positive end-expiratory pressure was increased from 0 (baseline) to 20 cm H2O in 5-cm H2O increments and RV hemodynamics and thermally derived right ventricular ejection fraction (RVEF), right ventricular end-diastolic volume index (RVEDVI), and right ventricular end-systolic volume index (RVESVI) were computed. Right ventricular contractility was determined from the analysis of RV systolic pressure-volume relations. Right ventricular ejection fraction declined from 42 +/- 8% at baseline to 30 +/- 9% at 20 cm H2O PEEP. Right ventricular end-diastolic volume index declined between 0 and 5 cm H2O PEEP (103 +/- 42 to 92 +/- 34 ml.m-2) and then increased to 113 +/- 40 at 20 cm H2O PEEP. Right ventricular end-systolic volume index increased from 60 +/- 31 ml.m-2 at baseline to 79 +/- 34 ml.m-2 at 20 cm H2O PEEP. The slope (E) of the relation of RV peak systolic pressure to RV end-systolic volume index decreased from 0.26 mm Hg.m2.ml-1 between PEEP of 0-15 cm H2O to 0.05 mm Hg.m2.m-1 at PEEP greater than 15 cm H2O. It is concluded that low levels of PEEP have a predominant preload reducing effect on the RV. Above 15 cm H2O PEEP, RV volumes increase and E decreases, consistent with increased RV afterload and a decline in RV contractility.     

心室压力-容量环评价非体外循环冠状动脉旁路移植术患者术中右心室功能的变化

目的 采用心室压力-容量环(P-V环)评价非体外循环冠状动脉旁路移植术(OPCABG)患者术中右心室功能的变化.方法 择期行OPCABG的三支病变冠心病患者28例,年龄53～76岁,ASAⅡ或Ⅲ级.经右颈内静脉穿刺,置入肺动脉导管,于切皮前(T1)、心脏前壁、侧壁、后壁血管搭桥并放置心肌固定器后5 min(T2-4)、术毕缝皮(T5)时记录血液动力学指标;记录舒张末期、等容收缩末期、射血峰压期、收缩末期、等容舒张末期右心室压力及容量数据,绘制右心室P-V环(以A点代表舒张末期,A'点代表收缩末期),并计算右心室收缩末期弹性(EES)及舒张末期僵硬度(EED).结果 T1-5,时右心室P-V环大致向坐标轴左上方移动,其中A点向左上方移动,A'点未见明显移动.与T1时比较,T2-5时EED功升高(P<0.05);EES各时点间差异无统计学意义(P>0.05).结论 右心室P-V环结果分析显示:OPCABG患者术中右心室功能抑制与右心室壁顺应性降低有关,与心肌收缩力无关.     

Heart rate-right ventricular stroke volume relation with myocardial revascularization

Whether increasing pacing frequency in cardiac surgical patients effectively improves right ventricular cardiac index depends on the interrelationships between heart rate, stroke volume index, and end-diastolic volume index. If an inverse relation exists between heart rate and right ventricular volume then the decrease in right ventricular ejection fraction described after bypass may be due, in part, to changes in heart rate. We evaluated the effects of pacing at 80, 95, and 110 beats/min using a thermodilution volumetric catheter in 16 patients undergoing myocardial revascularization. End-diastolic volume index, stroke volume index, and stroke work index were significantly greater after bypass than before bypass, whereas right ventricular ejection fraction remained constant. Before and after bypass, sequentially increasing pacing frequency from 80 to 110 beats/min decreased stroke volume index by 28% to 35% (p less than 0.001), end-diastolic volume index by 12% to 14% (p less than 0.001), and right ventricular ejection fraction by 18% to 24% (p less than 0.001). Right ventricular performance, assessed by comparing the stroke volume index to end-diastolic volume index and stroke work index to end-diastolic volume index relations generated during pacing, was not altered by bypass. We conclude that sequentially increasing heart rate from 80 to 110 beats/min fails to improve stroke volume index and consequently cardiac index before or after cardiac operations. Intraoperatively, in patients with normal left ventricular function, increasing pacing frequency decreases right ventricular ejection fraction due to simultaneous reductions in stroke volume index and end-diastolic volume index.     

The evaluation of incremental positive end-expiratory pressure on right ventricular hemodynamics as determined by the thermodilution technique

Effects of incremental positive end-expiratory pressure (PEEP) on right ventricular (RV) hemodynamics were studied in 10 patients undergoing coronary artery bypass grafting, abdominal aneurysmectomy and partial hepatectomy, using Swan-Ganz catheter mounted with the rapid response thermistor. PEEP was increased from 0 (baseline) to 15 cmH2O with increment of 5 cmH2O, and right ventricular ejection fraction (RVEF), RV end-diastolic volume (RVEDV), RV end-systolic volume (RVESV), and cardiac output (CO) were computed with a thermodilution technique at each PEEP. At 15 cmH2O PEEP, RVEF, RVEDVI and RVESVI were comparable with the baseline, while right arterial pressure, RV peak systolic pressure and mean pulmonary arterial pressure increased significantly compared with the baseline. Increased afterload of RN caused by PEEP did not affect RV contractility. Decreased cardiac and stroke volume indices were attributed to the decrease of preload caused by the increase of intrathoracic pressure. We conclude that PEEP at 5 to 15 cmH2O does not influence right ventricular hemodynamics, and RVEDV is a reliable index to monitor RV hemodynamics instead of right arterial pressure to determine optimal PEEP.     

Retrograde versus antegrade cardioplegia: impact on right ventricular function.

Retrograde cardioplegia administered through the coronary sinus has several documented advantages over antegrade cardioplegia but has been thought to provide inadequate right ventricular myocardial protection. We prospectively compared the effects of retrograde and antegrade cardioplegia on right ventricular performance in patients undergoing myocardial revascularization. Two groups of similar age, extent of disease, and preoperative left ventricular ejection fraction received retrograde (n = 16) or antegrade (n = 14) crystalloid cardioplegia. A right ventricular rapid-response thermistor catheter, previously developed and validated in our institution, was used to measure right atrial pressure, pulmonary artery pressure, right ventricular ejection fraction, end-diastolic volume index, and stroke volume index before bypass (baseline) and at several intervals after bypass. There were no differences in cross-clamp time, heart rate, cardiac enzymes, inotrope requirements, or arrhythmias between the two groups. Right ventricular parameters were equivalent in both groups at all time intervals except 30 minutes after bypass, at which time right ventricular end-diastolic volume index was lower (80 +/- 6 versus 93 +/- 6 mL/m2; p less than 0.05) and right ventricular stroke volume index was higher (35 +/- 3 versus 29 +/- 2 mL/m2, p less than 0.05) in the retrograde group compared with the antegrade group, indicating better right ventricular function with retrograde cardioplegia early after bypass. In both groups, right ventricular end-diastolic volume index was higher than baseline (p less than 0.05) during the first 4 hours after bypass. No other important differences were found.(ABSTRACT TRUNCATED AT 250 WORDS)     

Dor operation combined with redo coronary artery bypass grafting; report of two successful cases

Case 1. A 69-year-old male, who had undergone coronary artery bypass grafting with saphenous vein graft for acute myocardial infarction 16 years previously, was admitted into our hospital for heart failure and recurrent angina. Coronary angiography showed occlusion of the graft and 75% stenosis in the proximal circumflex artery. Left ventriculography showed end-diastolic volume of 216 ml and ejection fraction of 24%. Dor operation combined with redo coronary artery bypass grafting was performed. Postoperatively, the ejection fraction improved to 53% and the cardiac index improved from 1.8 to 2.2 l/min/m2. Case 2. A 67-year-old male, who had undergone double coronary artery bypass grafting using saphenous vein grafts for acute myocardial infarction 8 years previously, was admitted into our hospital for heart failure and recurrent angina. Coronary angiography showed occlusion of the 2 grafts and 99% stenosis of the proximal left anterior descending artery. Although the left ventricle was slightly dilated, echocardiography demonstrated a thrombus in the left ventricle. Dor operation was performed concomitantly with removing of the thrombus and redo coronary artery bypass grafting. Postoperatively, the ejection fraction improved to 68% and the cardiac index improved from 1.6 to 2.3 l/min/m2. When the patients underwent coronary artery bypass surgery with saphenous vein grafts for acute myocardial infarction, they could be susceptible to left ventricular asynergy and graft failure on the long run. Therefore, the patients who need redo coronary revascularization may be potential candidates for Dor operation, and they require close examination regarding the myocardial viability, volume and shape of the left ventricle.     

A comparison of nitroglycerin and nitroprusside: I. Treatment of postoperative hypertension

Nitroglycerin improves perfusion to ischemic myocardial regions and therefore has theoretical advantages over sodium nitroprusside to treat hypertension (mean arterial pressure [MAP] greater than 95 mm Hg) following coronary bypass operation. Thirty-three hypertensive patients were randomized to an initial infusion of either nitroglycerin or nitroprusside in a crossover trial designed to reduce MAP to 85 mm Hg. Thermodilution cardiac output measurements permitted calculation of left ventricular stroke work index (LVSWI), and nuclear ventriculograms permitted estimation of left ventricular ejection fraction, left ventricular end-diastolic volume index (LVEDVI), and left ventricular end-systolic volume index (LVESVI). Coronary sinus blood flow was measured by the continuous thermodilution technique, and arterial and coronary sinus lactate measurements permitted calculation of myocardial lactate flux (MVL). Both nitroglycerin and nitroprusside reduced MAP (-25 +/- 12 mm Hg and -20 +/- 10 mm Hg, respectively; not significant [NS]). Nitroglycerin reduced LVSWI more than did nitroprusside (-15 +/- 13 gm-m/m2 and -7 +/- 9 gm-m/m2, respectively; p less than 0.01). Both agents increased left ventricular ejection fraction (nitroglycerin, +8 +/- 8%, and nitroprusside, +10 +/- 7%; NS), and decreased LVEDVI (-20 +/- 22 ml/m2 and -11 +/- 17 ml/m2, respectively; NS) and LVESVI (-13 +/- 14 ml/m2 and -10 +/- 12 ml/m2, respectively; NS). Coronary sinus blood flow decreased with both drugs (NS), but MVL increased with nitroglycerin (+0.02 +/- 0.14 mmol/min) and decreased with nitroprusside (-0.02 +/- 0.02 mmol/min) (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Reverse-remodeling after coronary artery bypass grafting in ischemic cardiomyopathy: assessment of myocardial viability by delayed-enhanced magnetic resonance imaging can help cardiac surgeons

Preoperative delayed-enhanced magnetic resonance imaging (DE-MRI) was performed to estimate myocardial viability in a 57-year-old man with ischemic cardiomyopathy in order to decide the best course of treatment. The patient was diagnosed as having congestive heart failure with triple-vessel involvement (ejection fraction of 7%, end-diastolic volume index of 160 ml/m2, end-systolic volume index of 148 ml/m2). 99mTc-sestamibi single-photon emission computed tomography revealed severe reduction of the uptake at both stress and resting phases in the anterior, lateral and inferior segments. However, DE-MRI demonstrated transmural hyperenhancement to be <25% within the whole ventricular wall, implying that, though there was extensive subendoventricular myocardial infarction, there was substantial viable myocardium. Therefore, with the expectation that functional recovery was possible with coronary revascularization alone, we performed a complete revascularization with off-pump coronary artery bypass grafting. Six months after the operation, catheterization demonstrated dramatic improvement in ventricular function, with the ejection fraction having increased to 36%. This case suggests that preoperative assessment of myocardial viability by DE-MRI could help cardiac surgeons to choose the best treatment for patients with ischemic cardiomyopathy.     

Efficacy of Retrograde Coronary Sinus Cardioplegia in Patients Undergoing Myocardial Revascularization: A Prospective Randomized Trial

The efficacy of retrograde coronary sinus cardioplegia (RCSC) administered through the right atrium compared with aortic root cardioplegia (ARC) has not been examined critically in patients undergoing coronary artery bypass grafting (CABG). Twenty patients having elective CABG were randomized prospectively to receive cold blood ARC (Group I, 10 patients) or cold blood RCSC (Group II, 10 patients). Patient demographics were similar in both groups. Ventricular function was assessed preoperatively by radionuclide ventriculography and post-operatively by simultaneous hemodynamic and radionuclide ventriculographic studies with volume loading. There was no change in ejection fraction (EF) (preoperative versus postoperative value) in Group I (50 ± 6% versus 53 ± 6%) but in group II, at similar peak systolic pressure and similar left ventricular end-diastolic volume index (LVEDVI), LVEF improved significantly (49 ± 6% versus 60 ± 12%, p < 0.05). Postoperative ventricular function (stroke work index versus EDVI) for the left ventricle and right ventricle were similar in both groups. Evaluation of postoperative LV systolic function (end-systolic blood pressure versus end-systolic volume index) and diastolic function (pulmonary capillary wedge pressure versus EDVI) were also similar in both groups.Retrograde coronary sinus cardioplegia is as effective as ARC for intraoperative myocardial protection, and provides excellent postoperative function in patients undergoing elective CABG.     

Perioperative Hemodynamics in Patients Undergoing Partial Left Ventriculectomy

OBJECTIVES: Effects of partial left ventriculectomy (PLV) were studied by analyzing perioperative hemodynamics with measurements of left ventricular (LV) pressure-volume (PV) relationships and thermodilution catheter measurements in the pulmonary artery. METHODS: Between July and October 1996, 43 consecutive patients underwent PLV with and without mitral valvuloplasty with a thermodilution catheter and PV loop analysis immediately before and after surgery. Patients were 52+/-13 years and 67+/-13 kg, with reduced functional capacity (New York Heart Association 3.3+/-0.3) due to cardiomyopathy (24), ischemic disease (13), valvular disease (3), and Chagas' disease (3). RESULTS: PLV required cardiopulmonary bypass for 44+/-24 minutes, with the heart arrested in 10 patients for 26+/-22 minutes for coronary artery bypass grafting (8), aortic valve replacement (2), and autotransplantation (2). Two patients failed to come off bypass, six died in the hospital and 35 (35 [81.4%] of 43) were discharged. Changes in PV loops included decreased end-diastolic and end-systolic volume, resulting in no change in stroke volume. Pulmonary artery wedge pressure decreased despite elevated end-diastolic pressure. Ejection fraction, end-systolic elastance (E-max), afterload recruitable stroke work, and volume intercepts all improved and resulted in similar stroke work with less energy expenditure (less PV area), thus improving myocardial energetic efficiency. CONCLUSION: Results suggest that PLV improves systolic function but decreases diastolic compliance, which results in reduced net ventricular function immediately after surgery. Thus, immediate hemodynamic improvements appeared to derive from reduced severity in mitral regurgitation and perioperative load manipulation. Improved myocardial energetics may ameliorate LV function and improve the course of underlying myocardial disease.     

Right ventricular function computed by thermodilution and ventriculography. A comparison of methods

Right ventricular ejection fractions have been difficult to estimate clinically. It has been recently suggested that right ventricular ejection fractions can be calculated by thermodilution techniques with a fast-response thermistor and computer. These studies were performed to compare right ventricular ejection fractions obtained from thermodilution and biplane ventriculography. Ten pigs were instrumented with a right ventricular angiographic, thermodilution, and systemic arterial catheter. Right ventricular ejection fractions were determined by thermodilution and ventriculography at four times: (1) baseline, (2) infusion of isoporterenol (5 micrograms/min), (3) 50% of baseline mean arterial pressure produced by hemorrhage, and (4) reinfusion of isoproterenol during hypovolemia. A significant correlation existed between thermodilution and ventriculographic ejection fractions (r = 0.74, p = 0.004). However, during hypovolemia, thermodilution measurements of right ventricular ejection fraction were significantly lower than ventriculographic measurements (p less than 0.05). To determine if the position of the thermistor had a significant effect on thermodilution computations, right ventricular ejection fractions were computed by thermodilution in 10 additional pigs by means of a jugular and femoral insertion, as well as by ventriculography in each pig. Femoral insertion resulted in a greater distance from pulmonic valve to thermistor as compared with jugular placement (p = 0.005). Right ventricular ejection fractions obtained from femoral placement were significantly less than those obtained by jugular insertion (p = 0.008) and ventriculography (p = 0.006). There was no significant difference between jugular and ventriculographic ejection fractions (p = 0.35). Results from these studies demonstrates that thermodilution right ventricular ejection fraction measurements are strongly correlated to ventriculographic methods over a wide hemodynamic range and that improved accuracy is obtained when the pulmonic valve to thermistor distance is minimized. Thus thermodilution may provide a simple and repeatable means to monitor right ventricular function in the critical care setting.     

Age and right ventricular function during cardiac surgery.

Elderly patients undergoing cardiac surgery are reported to be at a higher risk for circulatory failure than younger patients, most likely because of ventricular decompensation. To assess the role of the right heart in these patients, right ventricular (RV) hemodynamics in 40 consecutive elderly patients (greater than 70 years; mean = 77.1 +/- 3.4 years) were compared with 40 consecutive younger patients (50 to 60 years; mean = 55.2 +/- 3.0 years) undergoing elective coronary artery bypass surgery. In addition to standard hemodynamic variables, RV ejection fraction (RVEF) and RV end-systolic and end-diastolic volumes (RVESV, RVEDV) were studied perioperatively using a thermodilution technique. None of the elderly patients died in the perioperative period. The course of RV function was comparable in both groups during the entire investigation period, but the absolute values of RVEF before the onset of cardiopulmonary bypass (CPB) were significantly higher in the younger patients (48.0 +/- 4.4%) than in the older patients (38.9 +/- 4.6%). RVEDV and RVESV were always higher in the older patients in the pre-bypass period than in the control group. None of the other hemodynamic parameters showed significant differences between the groups. Analysis of covariance showed no correlation between RV volume and pressure parameters. Inotropic support during and after termination of CPB was necessary more often in the older (epinephrine, 6.7 +/- 2.0 micrograms/min) than in the younger patients (epinephrine, 4.4 +/- 2.2 micrograms/min). It is concluded that older patients undergoing myocardial revascularization can have excellent results. However, they may be predisposed to right heart complications because of their reduced RV function.     

Hemodynamic unloading of the failing left ventricle using an arterial-to-arterial extracorporeal flow circuit

We tested the hypothesis that creation of a constant-flow extracorporeal circuit between the proximal and distal aorta will unload the failing left ventricle.Studies were performed in 14 heart failure dogs produced by intracoronary microembolizations. An extracorporeal circuit incorporating a diagonal pump was placed between a femoral and a carotid artery, with flow directed to the carotid. Hemodynamic measurements were made with the pump delivering 0.25 L/min through the circuit for 4 hours (active group). Measurements obtained from 8 sham-operated heart failure dogs were used for comparison (control group). Heart rate, peak left ventricular systolic pressure, left ventricular end-diastolic pressure, end-diastolic volume, end-systolic volume, and ejection fraction were measured at baseline and at 30, 60, 120, and 240 minutes.There were no differences in any of the hemodynamic values during the 4 hours of follow-up in the control group. In the active group, there was no effect on heart rate or peak systolic pressure, but reductions between baseline and 240 minutes were observed in left ventricular end-diastolic pressure (15 +/- 1 vs 6 +/- 1 mm Hg, p < 0.05), end-diastolic volume (61 +/- 3 vs 50 +/- 3 mL, p < 0.05), and end-systolic volume (44 +/- 2 vs 32 +/- 2 mL, p < 0.05), and an increase in ejection fraction (28 +/- 2 vs 37% +/- 2%, p < 0.05).Acute use of this artery-to-artery extracorporeal system effectively unloads the failing left ventricle. The potential benefits of this approach on long-term myocardial recovery in heart failure require further investigation.