左心室部分切除术治疗终末期心力衰竭

目的　对终末期扩张型心肌病患者采用外科左心室部分切除术减小左心室容积 ,并观察缓解心力衰竭 (心衰 )的疗效。方法　 4例患有进行性加重的充血性心衰患者的病因分别为原发性(2例 )、瓣膜性(1例 )和缺血性 (1例 )心肌病 ,所采用的术式包括“乳头肌间室壁切除”1例及“超乳头肌室壁切除”3例 (后者含二尖瓣替换)。同期手术还包括主动脉瓣替换 2例和冠状动脉搭桥 1例。结果　所有患者都顺利脱离体外循环 ,并在术后 (2 5± 2 )小时拔除气管插管。心输出量由术前 (2 0±0 2 )升 /min增至术后 (4 1±0 3 )升 /min(P =0 .0 0 1)。除 1例患者 3周后死于细菌性纵隔感染所致败血症外 ,另 3例平均 14天后出院。随访 (最多达 2 2个月 )证实这 3例患者均保持在纽约心脏协会心功能Ⅰ级。结论　左心室部分切除术为终末期扩张型心肌病患者缓解心衰症状 ,早期临床效果良好。     

Left ventricular volume characteristics in children with tricuspid atresia before and after surgery

Left ventricular volume variables (left ventricular end-diastolic volume, ejection fraction, mass and systolic output) were quantified in (1) 13 patients with tricuspid atresia preoperatively (type Ia, 3 patients; type Ib, 9 patients; type IIb, 1 patient), (2) 4 patients after a shunt procedure (Blalock-Taussig, 3; Glenn, 1), and (3) 1 patient after corrective surgery. Cardiac catheterization and angiography were performed at age 1 month to 5.8 years (mean 1.4 years). All patients had decreased pulmonary blood flow. The results were compared with data in 15 patients with no significant heart disease. Left ventricular end-diastolic volume was significantly greater than normal in 12 of the 13 patients. Left ventricular mass was significantly greater than normal, but ejection fraction was significantly less than normal. There was a positive correlation between ejection fraction and systemic oxygen saturation. Left ventricular systolic index was normal in 9 of the 13 patients preoperatively. After a shunt procedure, left ventricular end-diastolic volume and systolic index increased significantly in all four patients, and ejection fraction improved greatly in three of the four. After corrective surgery, left ventricular end-diastolic volume and left ventricular systolic index returned to the normal range and left ventricular ejection fraction improved. These findings suggest that patients with tricuspid atresia have impaired left ventricular function.     

Lung volume reduction surgery

Lung volume reduction surgery (LVRS) has been widely studied and has been available for the treatment of advanced emphysema for 10 years. This paper reviews some of the historical attempts at surgical treatment of emphysema, the physiology of LVRS, and the modern data on patient selection, risks, and benefits. Data from the National Emphysema Treatment Trial are presented in the context of the large body of case series and smaller randomized trials that have preceded that study. Future technologies of bronchoscopic lung volume reduction are also discussed.     

Left ventricular mass, volume and biopsy analysis in prediction of ventricular function after surgery for chronic aortic regurgitation

The serial application of electrocardiography and echocardiography to 67 selected patients undergoing valve replacement for chronic severe aortic regurgitation, documented regression of hypertrophy and chamber size within six to twelve months of surgery in all cases experiencing haemodynamic improvement. Those patients who had persistently increased patterns of myocardial hypertrophy and abnormal end-diastolic dimensions in the presence of normal prosthetic (homograft) function usually had persistent, irreversibly depressed myocardial function postoperatively. Preoperative noninvasive and angiographic characteristics could not predict ventricular function after surgery. Thus we could not precisely define what level of depressed ventricular performance or what degree of dilatation and myocardial hypertrophy constituted an irreversible state from this data. Although operative factors such as myocardial protection during cardiopulmonary bypass may influence postoperative cardiac performance, preoperative histological and histochemical data was useful in delineating irreversible morphological and function changes contributing to a depressed cardiac function, and therefore may be of prognostic importance.     

Effect of lung volume reduction surgery for severe emphysema on right ventricular function

Lung volume reduction surgery (LVRS) can improve the functional capacity of selected patients with severe emphysema. Hypothesized physiologic effects of LVRS include an improvement in right ventricular function, although this has not been investigated in detail. To help clarify this issue, we used fast-thermistor thermodilution at rest and during submaximal upright exercise in 12 patients, before and 6 mo after bilateral LVRS. Preoperatively, all patients had severe airflow obstruction, with a mean FEV(1) of 0.69 L and an RV-to-TLC ratio of 0.67. Six months after LVRS, significant improvements occurred in respiratory function measures (+0.39 L in FEV(1), p < 0.002; and +/- 0.15 in RV/TLC ratio, p < 0.002) and in right ventricular function indexes measured at rest (+0.21 L in cardiac index [CI], p < 0.01; and +3.0 ml in stroke volume, p < 0.01) and during exercise (+0.9 L in CI, p < 0.002; +10.0 ml in stroke volume index, p < 0.002; and +20% in ejection fraction [EF], p < 0.002). A significant correlation was found between pre- to postoperative changes in the EF response to exercise and changes in the RV/TLC ratio (R = -0.68; p = 0.01). We conclude that a significant improvement in right ventricular performance, particularly during exercise, can occur 6 mo after bilateral LVRS.     

Left ventricular pressure/volume relationship in aortic regurgitation

In this study we examined the left ventricular pressure/volume relationship in 39 patients with moderate or severe aortic regurgitation (AR) and 15 normal subjects. The patients with AR were divided into two groups; patients with normal resting ejection fraction (EF greater than or equal to 50%, group I, n = 21) and patients with abnormal EF (group II, n = 18). The patients in group I were younger (p less than 0.005), exercised to a higher workload, and had better exercise tolerance than patients in group II (p less than 0.01). The patients' exercise heart rate and blood pressure were not significantly different between the two groups. During exercise tests nine patients in group I and seven patients in group II had normal EF response (greater than or equal to 5% increase) (p = NS). The peak systolic blood pressure to end-systolic volume index ratio (SBP/ESVI) was higher in normal subjects than in patients in groups I and II, at rest it was (4.3 +/- 1.0 vs 2.6 +/- 1.2 vs 1.6 +/- 0.8, respectively, p less than 0.0001) and during exercise it was (7.6 +/- 1.8 vs 4.2 +/- 1.4 vs 2.6 +/- 1.3, respectively, p less than 0.0001). The resting SBP/ESVI ratio was below the lower normal limit in 12 patients (57%) in group I and in 16 patients (89%) in group II. Also, the exercise SBP/ESVI ratio was below the lower normal limit in 17 patients (81%) in group I and all of the patients (100%) in group II. Multivariate discriminant analysis identified the change in SBP/ESVI (F = 34.8) and resting end-diastolic volume (F = 6.7) as independent predictors of the EF response to exercise. Thus, most patients with AR, including those with normal resting EF or normal EF response to exercise, have abnormal SBP/ESVI at rest or during exercise.     

Left ventricular volume measurement; the accuracy of the measurement

Volume angiography is a widely diffused technique in hemodynamic laboratories despite several factors which limit the validity of the method. We have evaluated three of these factors: a) indefiniteness in the identification of the contour of the left ventricular cavity on the projected image; b) indefiniteness due to the reproducibility in tracing the contour of the left ventricular cavity by the same operator; c) indefiniteness related to the geometrical assumption (ellipsoid of revolution). The indefiniteness, given as per cent variation from the mean value, has been determined for the diastolic as well as systolic phase. The maximal possible indefiniteness, for diastole and systole, in contours identification in 15 cases has been found to be +/- 11.3% and +/- 24% of the mean volume. Intra observer reproducibility evaluated outlining 30 times the left ventricular contour has been equal to a mean difference from the mean volume of +/- 1.2% for diastole and +/- 4% for systole. The mean difference of the mean volume calculated with the area-lenght method (ellipsoid geometry) from the volume calculated with the Simpson rule has been, on 15 cases, equal to 4% in diastole and 11% in systole. This high level of indefiniteness, mainly for the systolic phase, must be considered before giving a value excessively precise to the volume data obtained with angiography. On the other hand, the method retains an orientative meaning extremely useful in clinical evaluation.     

Left ventricular pressure effects on right ventricular pressure and volume outflow

Massive destruction of the right ventricular free wall has been shown to cause only mild hemodynamic alterations. Further, the derivative of right ventricular (RV) pressure (P) is broad or double peaked, with one peak occurring coincidentally with peak left ventricular (LV) dP/dt. Both observations suggest a direct LV assistance to RV function. Since the ventricles contract nearly simultaneously, the relative contribution of LV to RV pump function has been difficult to determine. This LV assistance was quantified in six canine experiments using a unique electrically isolated RV preparation. While on total cardiopulmonary bypass, the RV free wall was electrically isolated from the remainder of the heart. This preparation allowed for wide variations in the timing interval between RV and LV contractions. Double-peaked waveforms for RVP and pulmonary flow (RVF) occurred over a wide range (0 to 300 ms) of pacing intervals between the RV and LV. One derivative peak always followed RV contraction for RVP and RVF (r = 0.971 +/- .011, P less than 0.01: r = 0.972 +/- .012, p less than 0.01; respectively). The second derivative peak was unrelated to the RA-RV pacing interval (r = 0.297 +/- .191, P greater than 0.5 RVP; 4 = 0.237 +/- .278, P greater than 0.5 RVF), but corresponded to the maximal LVP rise. Additionally, the magnitude of the two derivative peaks was similar when the ventricles contracted synchronously. When RV contraction preceded or followed LV contraction, the derivative peak associated with LV contraction was significantly greater (P less than 0.05, range 2.1 +/- 0.6 to 6.7 +/- 1.6 for RVP; P less than 0.05 range 1.9 +/- 0.4 to 6.7 +/- 1.5 for RVF) than the derivative associated with RV contraction. These data demonstrate a normally present, large LV assistance to RV contraction and may help to explain the RV response to myocardial infarction.     

Left ventricular pressure/volume relationship in coronary artery disease

This study examined the changes during exercise in LV EF and P/V relationship (systolic blood pressure/end-systolic volume index ratio) in 287 patients. Normal range (mean +/- standard deviation) for exercise EF, exercise P/V, and the changes from rest to exercise (delta) in EF and P/V were established in 51 subjects with less than 1% probability of CAD. The results were compared to those obtained in 53 patients with normal coronary angiograms and 183 patients with angiographically proven CAD. Abnormality in either delta EF or percent delta P/V were observed in 76% of the patients with one-vessel disease and in 91% of patients with multivessel disease. Abnormalities in either delta EF or percent delta P/V were more common than delta EF alone in the total CAD group and in subgroups stratified according to the resting EF, extent of CAD, and adequacy of exercise end points. Similar results were obtained when absolute exercise EF or exercise P/V were used. Abnormalities in the percent delta P/V or delta EF were also seen in 26 of the 53 patients with normal coronary angiograms. Thus, abnormalities in the P/V relationship or EF during exercise are more common than abnormalities in the EF alone. Relative and absolute measurements provide similar results.     

Left ventricular end-systolic pressure volume relations in healthy young men

The purpose of the present study was to establish the relationshipof left ventricular end-systolic volume vs. mean systemic pressurein variously afterloaded beats in a group of healthy, young,men (n=6, age 24±0.9 years). The relationship was expressedby the slope (E_max) of the line connecting pressure-volume co-ordinatesand its extrapolated intercept (V_d) of the volume axis. Theslope was calculated by linear regression of mean systemic arterialpressure (mean SAP, measured by catheter in the radial artery)vs. end-systolic left ventricular volume (ESV, estimated fromcross-sectional, 4-chamber echocardiographic images). Recordingswere obtained at resting, reduced (nitroglycerin infusion),and elevated (metaoxedrin infusion) blood pressure. IndividualE_max values ranged from 1.05 to 2.01 mmHg ml^–1; Vd wasconsistently found to be negative, ranging from –4.7 to–54.8 ml. All individual relations were statisticallysignificant (P<005 to P<0001). Group values were E_max=1.27±0.25(SE) mmHg ml^–1, V_d=–43.3±7.5 (SE) ml, andE_max indexed for body surface area, E_{max ind} ±=2.54±0.49(SE) mmHg ml^–1 m^–2. We further examined the validityof proposed optimal relations among E_max, heart rate (HR) andsystemic resistance (R_s): E^max/HR=R_s, and among ejection fraction(EF), EDV and V_d: EF=0.5 (1–EDV/V_d). For the group E_max/HR/0023±0.003and R_s=0016±0004 (mmHg ml^–1 min^–1), i.e.,a deviation from equivalence of 30% (P<0.001). EF (=0.72±0.02)deviated by 18% (P<0001) from its proposed optimum (0.5 (1–V_d/EDV)=0.61=006).     

Lung volume reduction surgery for emphysema

Over the past decades, extensive literature has been published regarding surgical therapies for advanced COPD. Lung-volume reduction surgery would be an option for a significantly larger number of patients than classic bullectomy or lung transplantation. Unfortunately, the initial enthusiasm has been tempered by major questions regarding the optimal surgical approach, safety, firm selection criteria, and confirmation of long-term benefits. In fact, the long-term follow-up reported in patients undergoing classical bullectomy should serve to caution against unbridled enthusiasm for the indiscriminate application of LVRS. Those with the worst long-term outcome despite favourable short-term improvements after bullectomy have consistently been those with the lowest pulmonary function and significant emphysema in the remaining lung who appear remarkably similar to those being evaluated for LVRS. With this in mind, the National Heart, Lung and Blood Institute partnered with the Health Care Finance Administration to establish a multicenter, prospective, randomized study of intensive medical management, including pulmonary rehabilitation versus the same plus bilateral (by MS or VATS), known as the National Emphysema Treatment Trial. The primary objectives are to determine whether LVRS improves survival and exercise capacity. The secondary objectives will examine effects on pulmonary function and HRQL, compare surgical techniques, examine selection criteria for optimal response, identify criteria to determine those who are at prohibitive surgical risk, and examine long-term cost effectiveness. It is hoped that data collected from this novel, multicenter collaboration will place the role of LVRS in a clearer perspective for the physician caring for patients with advanced emphysema.