Assessment of cardiac function in patients who were morbidly obese

Cardiac function of 30 patients who were morbidly obese was studied before bariatric surgery. Twelve patients were studied 13 +/- 4 months after surgery. These patients had a mean age of 37.1 +/- 2.9 years and a body mass index of 50.0 +/- 1.4 kg/m2. Cardiac function was measured by echocardiography, radionuclide angiography scanning, and right heart catheterization. To determine the degree of cardiac dysfunction, the patients were studied with exercise and intravenous fluid challenges. Ultrasonography produced evidence of myocardial thickening with an increased interventricular septum in eight patients (32%) and increased left ventricular mass in 17 patients (53%). The radionuclide scan suggested that morbid obesity was associated with a significantly (p less than 0.05) increased end-diastolic volume and decreased left ventricular ejection fraction as compared with patients who were of normal weight. With exercise the patient who was of normal weight had an increase in the end-diastolic volume, stroke volume, and heart rate, but the patient who was morbidly obese only increased heart rate to produce the necessary increase in cardiac output. Right heart catheterization indicated that the relationship of the pulmonary wedge pressure and the left ventricular stroke work index was abnormal in 14 of 29 patients (48.3%) and depressed in six of 29 patients (20.7%) with exercise. One liter of fluid caused an abnormal relationship of the pulmonary wedge pressure and the left ventricular stroke work index in 12 of 30 patients (40%) and a depressed response in 10 of 30 patients (33.3%). Cardiac studies were repeated in 12 patients after a 54.8 +/- 1.9 kg weight loss. Echocardiography indicated a decrease in dilatation (27.3% to 9.1%) and a significant (p less than 0.05) decrease in hypertrophy (45.5% to 0%). After the weight loss, radionuclide and right heart catheterization studies indicated improved cardiac function with reduced filling pressures and increased left ventricular work during fluid and exercise challenges. These results support the presence of obesity-related cardiomyopathy with ventricular dysfunction, which appears to be caused by a noncompliant ventricle. Significant weight loss achieved with gastroplasty results in increased ventricular compliance and improved cardiac function.     

Ventricular energetics in endoventricular circular patch plasty for dyskinetic anterior left ventricular aneurysm

BACKGROUND: The endoventricular circular patch plasty (Dor procedure) applies to patients with a left ventricular dysfunction due to an ischemic dilated ventricle. In the present study, we analyzed left ventricular energetics in patients who underwent the Dor procedure. METHODS: We measured left ventricular contractility (end-systolic elastance; Ees), afterload (effective arterial elastance; Ea), and efficiency (ventriculoarterial coupling; Ea/Ees, and the ratio of stroke work and pressure-volume area; SW/PVA) based on the cardiac catheterization data before and after the Dor procedure in 8 patients with a postinfarction dyskinetic anterior left ventricular aneurysm. Concomitant procedures included coronary artery bypass grafting in all patients, mitral valve repair in one patient, and cryoablation in one patient. End-systolic elastance (Ees) and Ea were approximated as follows: Ees = mean arterial pressure/minimal left ventricular volume, and Ea = maximal left ventricular pressure/(maximal left ventricular volume-minimal left ventricular volume), and thereafter Ea/Ees and SW/PVA were calculated. The left ventricular volume was normalized with the body surface area. RESULTS: End-systolic elastance (Ees) increased after the Dor procedure (from 1.15 +/- 0.60 to 1.86 +/- 0.84 mm Hg x m2 x mL(-1), p < 0.01), thus resulting in an improvement in Ea/Ees and SW/PVA (from 2.94 +/- 1.11 to 1.64 +/- 0.49, p < 0.01, and from 0.426 +/- 0.110 to 0.559 +/- 0.082, p < 0.01, respectively), even though Ea did not substantially change (from 2.96 +/- 0.78 to 2.74 +/- 0.55 mm Hg x m2 x mL(-1), p = 0.4). CONCLUSIONS: Left ventricular contractility and efficiency improves after the Dor procedure in patients with a dyskinetic anterior left ventricular aneurysm. However, afterload does not change. The use of appropriate afterload-reducing therapy thus plays an especially important role in the management of patients who undergo the Dor procedure.     

Spontaneous Ventricular Arrhythmias Following Partial Left Ventriculectomy for Nonischemic Dilated Cardiomyopathy: Relation to Hemodynamics and Survival

The study assessed the value of ambulatory electrocardiogram (AECG) monitoring for identification of patients who are at increased risk for cardiac death or arrhythmic event following partial left ventriculectomy (PLV). Furthermore, the impact of PLV and its hemodynamics on the occurrence of spontaneous ventricular arrhythmias was assessed in long-term survivors. In 32 idiopathic dilated cardiomyopathy patients who underwent PLV, ambulatory ECG (AECG) was performed preoperatively, early postoperatively, and 6 months and 12 months after surgery. In 17 of 19 patients who survived > 12 months after the procedure, left ventricular (LV) angiography was performed at the same time points and was used to calculate LV ejection fraction, and end-diastolic and end-systolic wall stress. During a mean follow-up of 478 +/- 405 days, 11 cardiac events occurred. Cox univariate regression revealed frequency of premature ventricular contractions > 30/hour at baseline (p = 0.0213) and duration of heart failure symptoms (p = 0.0226) as predictors of cardiac death or arrhythmic event after PLV. In a multivariate analysis, only frequency of premature ventricular contractions > 30/hour was a significant predictor. There was no change in the frequency or severity of ventricular arrhythmias after PLV. However, frequency of premature ventricular contractions correlated with LV end-diastolic stress (r = 0.35, p = 0.013), and ejection fraction (r = -0.34, p = 0.016). Preoperative AECG monitoring may help stratification of PLV patients. Serial AECG did not show that PLV influence the incidence or the complexity of spontaneous ventricular arrhythmias. In contrast, it appears that a hemodynamically "successful" procedure may decrease the incidence of ventricular arrhythmias.     

Left ventricular performance before and after left ventriculotomy and removal of a left ventricular aneurysm

The effects of left ventriculotomy on left ventricular performance were studied in seven patients with ventricular tachyarrhythmia (VT) and nine patients with left ventricular aneurysm (LVA). Hemodynamic and left ventriculographic findings were evaluated before and after operations. In VT the non-contracting areas, measured at end-diastole, as mean 10.8 +/- 7.1% of the left ventricular internal surface area. There was no significant fall in left ventricular ejection fractions (EF), cardiac indexes (CI) and left ventricular end-diastolic volume indexes (LVEDVI) after left ventriculotomy. In LVA, the non-contracting areas decreased from 31.0 +/- 7.4% to 13.7 +/- 13.5% (p less than 0.01) in association with a reflex decrease in LVEDVI from 117 +/- 31.8 ml/m2 to 90.4 +/- 24.7 ml/m2 (p less than 0.05). EF increased from 40.8 +/- 7.00% to 54.6 +/- 10.7% (p less than 0.01). There was no significant change in CI and left ventricular stroke volume index after left ventricular aneurysmectomy. The observations indicate that left ventriculotomy of limited size is an acceptable and a safety approach to the ventricular tachyarrhythmias and another cardiac operations.     

Left ventricular function changes after cardiomyoplasty in patients with dilated cardiomyopathy

Dynamic cardiomyoplasty has been reported in the treatment of severe myocardial failure. In this investigation significant improvement of left ventricular function with dynamic cardiomyoplasty was demonstrated in patients with dilated cardiomyopathy or Chagas' disease for more than 1 year of follow-up. Thirteen patients with advanced heart failure who were in New York Heart Association class III or IV were operated on. There were no operative deaths. Patients were followed up for a mean of 11.5 months, and two patients died during the late follow-up period. Five of nine patients observed long term are in New York Heart Association class I, three in class II, and one in class III. At 3 months of follow-up, Doppler echocardiography demonstrated that left ventricular segmental wall shortening increased from 11.4% +/- 2.3% to 16.4% +/- 3.9% (p less than 0.01), and left ventricular stroke volume from 23.9 +/- 5.7 to 34.4 +/- 10 ml (p less than 0.01). Radioisotopic left ventricular ejection fraction improved from 20.9% +/- 3.3% to 25.4% +/- 7.7% (p = 0.06), and its better increases occurred in patients with lesser left ventricular end-diastolic dimensions. Cardiac catheterization showed that left ventricular stroke work index increased from 14.6 +/- 3.8 to 23.7 +/- 6.7 gm.m/m2 (p less than 0.01), whereas pulmonary wedge pressure decreased from 24.8 +/- 3.7 to 17.2 +/- 5.8 mm Hg (p less than 0.01). At 6 and 12 months of follow-up, all the preceding values remained essentially unchanged. Thus cardiomyoplasty improves left ventricular function and may halt the steady evolution of severe cardiomyopathies.     

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.     

Early changes in the time course of myocardial contraction after correcting aortic regurgitation

BACKGROUND: Correcting aortic regurgitation causes significant changes in left ventricular loading conditions, but few observations have been made intraoperatively of early effects on myocardial function. METHODS: We studied 18 patients (mean age, 59+/-12 years; 14 men) in whom aortic regurgitation was corrected with a stentless biologic valve. Overall left ventricular function was studied by thermodilution cardiac output, ventricular filling pressure, and systemic arterial pressure. Regional myocardial function was assessed from intraoperative transesophageal M-mode echocardiography and high fidelity ventricular pressure recordings before cardiopulmonary bypass, and 0.5, 1, 3, 6, 12, and 20 hours after operation. Time course of contraction, and magnitude of left ventricular systolic wall stress, dimensional shortening, myocardial power, and stroke work were measured. RESULTS: Global hemodynamics: there was an immediate decrease in left ventricular stroke volume (58+/-31 mL versus 80+/-30 mL, p = 0.004) and stroke work index (250+/-86 mJ/m versus 401+/-198 mJ/m, p = 0.005), but systemic arterial pressure (79+/-11 mm Hg versus 65+/-10 mm Hg, p = 0.002), increased at constant heart rate and end-diastolic pressure. Regional myocardial function and timing: peak systolic wall stress, dimensional shortening rate, and myocardial power production were all unchanged with operation. However, myocardial stroke work decreased (3.0+/-1.3 mJ/cm versus 4.8+/-2.4 mJ/cm, p = 0.009), attributable to shortening of the duration of systole (475+/-91 ms versus 543+/-67 ms, p<0.001). Diastolic time increased from 34%+/-18% to 71%+/-33% of systolic pulse duration (p<0.001). CONCLUSIONS: Correcting aortic regurgitation causes an early decrease in regional and global stroke work and increases diastolic time, although systolic wall stress does not decrease immediately. These beneficial effects are achieved by reducing the duration rather than altering the peak intensity (power) of myocardial contraction.     

Adriamycin-induced cardiomyopathy in the dog--an appropriate model for research on partial left ventriculectomy?

OBJECTIVE: To evaluate the adriamycin-induced cardiomyopathy in the dog for research on partial left ventriculectomy (PLV). METHODS: An intracoronary catheter was introduced into the left main stem via the first diagonal branch in a retrograde fashion in 6 adult FBI (Foxhound Boehringer Ingelheim) dogs weighing 30 to 35 kg. The catheter was connected to a percutaneous access port that was used for weekly adriamycin administration (10 mg over a 1-hour period for 5 times). Follow-up examinations (transthoracic echocardiography, hemodynamic parameters, cardiopulmonary status, and neurohormones) were done before, 1 week after the last adriamycin administration, and 6 weeks later. After the last measurements, all dogs were euthanized with saturated potassium chloride under general anesthesia and the hearts were excised for histologic examinations. All data were calculated as mean values and standard error of the mean. Differences were calculated by the Wilcoxon signed rank test for paired and unpaired data. p values less than 0.05 were considered significant. RESULTS: Central venous pressure (2.2 +/- 0.8 vs 5.2 +/- 0.4 mm Hg, p = 0.03), mean pulmonary artery pressure (8.6 +/- 1.1 vs 12.4 +/- 0.5 mm Hg, p = 0.03), pulmonary wedge pressure (2.6 +/- 0.9 vs 7.0 +/- 0 mm Hg, p = 0.03), left ventricular endsystolic diameter (2.5 +/- 0.2 vs 3.1 +/- 0.4 cm, p = 0.03), and enddiastolic (4.5 +/- 0.2 vs 4.9 +/- 0.2 cm, p = 0.03) diameter increased significantly after adriamycin administration, whereas cardiac output (4.0 +/- 0.3 vs 3.3 +/- 0.1 liter/min, p = 0.03), stroke volume index (66.0 +/- 7.4 vs 54.0 +/- 3.9 ml/beat/m(2), p = 0.03), and ejection fraction (61.1 +/- 5.1 vs 37.7 +/- 5.7%, p = 0.03) decreased markedly. These changes were accompanied by a significant decline of oxygen delivery (1130 +/- 170 vs 790 +/- 65 ml/min, p = 0.03), which led to an enhanced oxygen extraction (0.12 +/- 0.01 vs 0.24 +/- 0.01, p = 0.03). Consequently, venous oxygen saturation (82.7 +/- 4.1 vs 71.3 +/- 2.5%, p = 0.03) decreased. Troponin I (0.02 +/- 0.025 vs 1.7 +/- 0.6 ng/ml, p = 0.03) and the anti-diuretic hormone (1.9 +/- 0.9 vs 20.0 +/- 1.9 pg/ml, p = 0.03) increased significantly after adriamycin administration. Deterioration of cardiac function continued after termination of adriamycin administration, albeit slower than during adriamycin administration. All hearts had severe histologic alterations, which were characteristic of adriamycin-induced toxicity: cytoplasmic vacuolation, myocyte degeneration, and increased fibrosis. CONCLUSIONS: The adriamycin-induced cardiomyopathy in the dog is similar to the dilated cardiomyopathy in humans and may be an appropriate model for PLV.     

Coronary artery bypass surgery in patients with impaired left ventricular function. Predictors of hospital outcome

This prospective study evaluates the surgical outcome of 75 consecutive patients with impaired left ventricular function, including an analysis of predictors of the short-term outcome following coronary artery bypass grafting (CABG). Seventy-five patients (mean age 64 +/- 13 years) with coronary artery disease and impaired left ventricular function (left ventricular ejection fraction [EF] < or = 40%) who underwent a coronary artery bypass surgery were prospectively studied. Echocardiography and thallium-201 myocardial scintigraphy were preoperatively performed to measure the left ventricular function and to assess myocardial viability. Postoperative echocardiography was done before discharge and six months later to evaluate recovery of left ventricular function. Five patients (6.7%) died in total: three deaths were cardiac related (4%) and two patients (2.7%) died due to other causes. The left ventricular ejection fraction improved immediately after the operation (from 32.2 +/- 6% to 39.5 +/- 8%, p = 0.01) and showed a sustained improvement at later follow-up (mean = 16.3 +/- 4.5 months) (44.0 +/- 4.0%, p = 0.01). The left ventricular wall motion score improved significantly only at later follow-up (from 12.2 +/- 1.8 to 9.4 +/- 2.0, p = 0.03). In 43 patients of whom a preoperative thallium-201 scintigraphy was available, the presence of extensive reversible defects was correlated with significant improvement in EF. On the other hand, a poor outcome was correlated with the presence of pathological Q waves in the preoperative ECG and with an increased left ventricular end-systolic volume index (> 100 ml/m2). Patients with marked left ventricular dysfunction can safely undergo CABG with a low mortality and morbidity. The presence of extensive reversible defects on preoperative thallium-201 scintigraphy is a strong predictor of postoperative recovery of myocardial function. A poor outcome of surgery can be expected in the presence of pathological Q waves on the preoperative ECG or when the left ventricular endsystolic volume index exceeds 100 ml/m2.     

Evaluation of predictors of clinical outcome after partial left ventriculectomy

BACKGROUND: Outcome after partial left ventriculectomy (PLV) is difficult to predict. Our goal was to determine if clinical measurements including exercise testing could predict outcome after PLV. METHODS: Sixteen patients with dilated cardiomyopathy had left ventricular ejection fraction, left ventricular end-diastolic diameter, amount of mitral regurgitation (MR), New York Heart Association (NYHA) functional class, and cardiopulmonary exercise testing measurements measured before PLV and 3 months after PLV. Eleven patients who remained stable after PLV (group 1) were compared with 5 patients who deteriorated after PLV (group 2). RESULTS: Similar significant improvements were seen in both groups 3 months post-PLV with respect to left ventricular ejection fraction (group 1: 0.136+/-0.037 to 0.212+/-0.046; group 2: 0.139+/-0.042 to 0.179+/-0.073) and left ventricular end-diastolic diameter (group 1: 8.5+/-0.7 to 7.0+/-0.6 cm; group 2: 7.6+/-0.6 to 6.5+/-0.6 cm). The MR grade (1.0+/-0.6 versus 2.5+/-0.6), NYHA functional class (1.5+/-0.31 versus 2.5+/-0.6), and peak oxygen consumption (17.8+/-1.1 versus 12.2+/-2.0) were significantly different in the two groups 3 months after PLV (p < 0.05, analysis of variance). CONCLUSIONS: Patients that do not show significant improvement in peak oxygen consumption, NYHA class and significant decrease in the amount of MR 3 months after PLV, compared with pre-PLV, are at increased risk of clinically deteriorating.     

Pulmonary artery balloon counterpulsation in the management of right heart failure during left heart bypass

Pulmonary artery balloon counterpulsation was instituted in 10 pigs when right ventricular failure limited cardiac output. Global myocardial depression was produced by infusion of propranolol, and the left ventricle was fully supported by left heart bypass. A stable model of failure was achieved in six pigs. Following application of pulmonary artery balloon counterpulsation right atrial pressure decreased from 18.2 +/- 2.1 to 15.9 +/- 2.5 mm Hg (p less than 0.05). Cardiac output increased from 416 +/- 94 to 758 +/- 127 ml/min (p less than 0.001). Right ventricular stroke work increased from 0.29 +/- 0.07 to 0.65 +/- 0.12 gm X m. (p less than 0.05). There was no cardiac output before or after institution of balloon counterpulsation in four pigs studied during ventricular fibrillation or asystole. We conclude that pulmonary artery balloon counterpulsation improved cardiac output and right ventricular stroke work in a model of right ventricular failure where the pulmonary circulation was unaltered and the left ventricle supported by left heart bypass. Balloon counterpulsation was not effective during ventricular fibrillation or asystole. Pulmonary artery balloon counterpulsation should be considered when right ventricular failure limits cardiac output during left heart bypass.     

Glucose-insulin-potassium solution improves left ventricular mechanics in diabetes

BACKGROUND: The mechanism by which glucose-insulin-potassium solutions enhance recovery of left ventricular function after myocardial ischemia in diabetic patients is not well understood. We evaluated the effect of glucose-insulin-potassium on ventriculoarterial coupling and left ventricular mechanics in a chronic ovine model of diabetes. METHODS: Diabetes was induced in 6 sheep with streptozotocin. After 6 months of diabetes, the response of the left ventricular pressure-volume relationship to 60 minutes of intravenous glucose-insulin-potassium solution (1,000 mL of 5% dextrose in water, 100 IU of regular insulin, 90 mmol of KCl at 1.5 mL x kg(-1) x h(-1)) was determined. RESULTS: Glucose-insulin-potassium solution increased end-systolic elastance 68% (p = 0.01) and improved ventriculoarterial coupling (1.7+/-0.3 to 1.0+/-0.1; p < 0.01). Potential energy decreased 35% (p = 0.01), and pressure-volume area decreased 20% (p = 0.01). However, stroke work did not change; therefore stroke work efficiency increased from 50.1%+/-3.5% to 60.2%+/-5.1% (p = 0.01). CONCLUSIONS: Glucose-insulin-potassium solution improves left ventricular contractility and ventriculoarterial coupling in diabetes. Left ventricular mechanics is improved by decreasing total mechanical work without significantly affecting stroke work, resulting in improved stroke work efficiency. Improved efficiency facilitates understanding of the enhanced tolerance to myocardial ischemia afforded by glucose-insulin-potassium solution.     

Ethanol impairs cardiocirculatory function in treated canine hemorrhagic shock

This study examined the hypothesis that ethanol-induced alterations in cardiac function and regional blood flow impair recovery from shock after resuscitation. Blood ethanol levels 45 minutes after ethanol (3 gm/kg) was administered intrajejunally were 276 +/- 30 mg/100 ml (N = 14 dogs). Twelve dogs received saline solution and served as control animals. Elevated blood ethanol levels increased the rate of left ventricular pressure rise (+763 +/- 80 mm Hg X sec) and coronary blood flow (+0.77 +/- 0.18 ml X min X gm), decreased respiration, and caused a significant metabolic acidosis (arterial pH, 7.25 +/- 0.02; arterial lactate, 1.5 +/- 0.07 mmol/L). Two hours of hemorrhagic shock impaired cardiovascular function and regional blood flow to a similar extent in all dogs. Volume replacement (shed blood and lactated Ringer's solution, 50 ml/kg) transiently improved cardiac performance in the ethanol group. Two hours after volume replacement, a lower cardiac output, stroke volume, stroke work, myocardial oxygen efficiency, and persistent acidosis occurred in the intoxicated dogs (p less than 0.05) despite adequate coronary perfusion. Myocardial sensitivity to acidosis after shock may account for the reduced cardiac function in the ethanol group. However, it is possible that shock aggravated ethanol-induced pancreatic ischemia and contributed to impaired cardiocirculatory function in postinfusion shock.     

Left ventricular reshaping: effects on the pressure-volume relationship

OBJECTIVE: We tested whether the CardioClasp device (CardioClasp, Inc, Cincinnati, Ohio), a non-blood contact device, would improve left ventricular contractility by acutely reshaping the left ventricle and reducing left ventricular wall stress. METHODS: In dogs (n = 6) 4 weeks of ventricular pacing (210-240 ppm) induced severe heart failure. Left ventricular function was evaluated before and after placement of the CardioClasp device, which uses 2 indenting bars to reshape the left ventricle. Hemodynamics, echocardiography, and Sonometrics crystals dimension (Sonometrics Corporation, London, Ontario, Canada) were measured at steady state and during inferior vena caval occlusion. RESULTS: The CardioClasp device decreased the left ventricular end-diastolic anterior-posterior dimension by 22.8% +/- 1.9%, decreased left ventricular wall stress from 97.3 +/- 22.8 to 67.2 +/- 7.7 g/cm(2) (P =.003), and increased the fractional area of contraction from 21.3% +/- 10.5% to 31.3% +/- 18.1% (P =.002). The clasp did not alter left ventricular end-diastolic pressure, left ventricular pressure, left ventricular dP/dt, or cardiac output. With the CardioClasp device, the slope of the end-systolic pressure-volume relationship was increased from 1.87 +/- 0.47 to 3.22 +/- 1.55 mm Hg/mL (P =.02), the slope of preload recruitable stroke work versus end-diastolic volume was increased from 28.4 +/- 11.0 to 44.1 +/- 23.5 mm Hg (P =.02), and the slope of maximum dP/dt versus end-diastolic volume was increased from 10.6 +/- 4.6 to 18.6 +/- 7.4 mm Hg x s(-1) x mL(-1) (P =.01). The CardioClasp device increased the slope of the end-systolic pressure-volume relationship by 68.0% +/- 21.7%, the slope of preload recruitable stroke work versus end-diastolic volume by 50.7% +/- 18.1%, and the slope of maximum dP/dt versus end-diastolic volume by 85.7% +/- 28.9%. CONCLUSIONS: The CardioClasp device decreased left ventricular wall stress and increased the fractional area of contraction by reshaping the left ventricle. The CardioClasp device was able to maintain cardiac output and arterial pressure. The clasp increased global left ventricular contractility by increasing the slope of the end-systolic pressure-volume relationship, the slope of preload recruitable stroke work versus end-diastolic volume, and the slope of maximum dP/dt versus end-diastolic volume. In patients with heart failure, the CardioClasp device might be effective for clinical application.     

Effects of the left ventricular assist device on right ventricular function

Right ventricular failure is a leading cause of death in patients who require the left ventricular assist device. Previous reports suggested right ventricular functional deterioration during left ventricular assist but lacked a method by which right ventricular function could be quantified adequately. This study examined the effects of left ventricular volume unloading on right ventricular systolic function by means of the stroke work/end-diastolic volume relationship, a load-insensitive index of myocardial performance. In 12 anesthetized open-chested dogs, right ventricular and left ventricular pressures were measured with micromanometers while ultrasonic dimension transducers measured left and right ventricular orthogonal diameters. Left ventricular unloading was accomplished with left atrial-to-femoral artery bypass with a centrifugal pump. Data were recorded during transient vena caval occlusion in the control state and with maximal left ventricular unloading by full support by the left ventricular assist device. Modified ellipsoidal geometry was used to calculate simultaneous biventricular volumes, and linear regression analysis of right ventricular stroke work versus end-diastolic volume was used to quantify right ventricular systolic function. Average slope and x intercept of this relationship under control conditions were 2.2 +/- 0.3 X 10(4) erg/ml and 10.7 +/- 5.0 ml, respectively. During full support by the left ventricular assist device (mean flow rate, 2.4 +/- 0.3 L/min), left ventricular end-diastolic volume decreased by 31% (p less than 0.01), left ventricular septal-free wall diameter decreased by 7% (p less than 0.001), and rate of rise of right ventricular peak positive pressure declined by 13% (p less than 0.05). The corresponding slope and x intercept of the right ventricular stroke work/end-diastolic volume relationship during full unloading of left ventricular assist device were 2.3 +/- 0.3 X 0.3 X 10(4) erg/ml and 14.3 +/- 4.8 ml, respectively; these values were not significantly different from control values (p greater than 0.5). Additionally, analysis of right ventricular end-diastolic pressure-volume relationships suggested improved right ventricular chamber compliance, although the effects were small and did not reach statistical significance (p = 0.10). These data imply that marked alterations in biventricular geometry accompanying left ventricular volume unloading by the left ventricular assist device in a normal heart do not significantly alter right ventricular performance characteristics.     

Left ventricle restoration in patients with non-ischemic dilated cardiomyopathy: risk factors and predictors of outcome and change of mid-term ventricular function.

OBJECTIVE: The partial left ventriculectomy (PLV) for end-stage dilated cardiomyopathy (DCM) which worked in some patients has been reported, although the hospital mortality is high. To reduce hospital mortality, we selected operative procedures of left ventricular (LV) restoration to improve the operative results. We analyzed the risk factors and predictors of outcome, and the mid-term changes of the LV function were determined. PATIENTS AND METHODS: Between December 1996 and September 2000, 74 patients with non-ischemic DCM received LV restoration. The age ranged from 14 to 76 years (mean, 49.0+/-14.0 years), and there were 63 men and 11 women. The etiology of the DCM was idiopathic DCM in 49 patients, and dilated hypertrophic cardiomyopathy in seven patients and others in 18. The preoperative New York Heart Association (NYHA) functional class was 29 in class III and 45 in class IV, in which 32 patients depended on inotropic support. PLV or septal anterior ventricular exclusion (SAVE) was selected depending on the akinetic lesion of the LV based on the intraoperative echo-test. Fifty-six patients received elective operations, and emergency operations were performed in 18 patients. The risk factors and predictors of outcome were analyzed in 74 patients, and in 35 patients who survived more than 1 year after receiving LV restoration, the mid-term cardiac function was examined by cardiac echogram and catheterization. RESULTS: PLV was performed in 62 patients and SAVE in 12 patients. Concomitant mitral surgery was performed in 66 patients (89%) and tricuspid annuloplasty in 42 patients (57%). There were 15 hospital deaths and 13 patients died after discharge from the hospital (cardiac deaths in nine and non-cardiac deaths in four). In the 46 late survivors, the NYHA class was I or II in 42 patients and III in four patients. Selection of the procedure of LV restoration (P<0.01), elective operation (P<0.05), and the preoperative volume of LV (endodiastolic volume index of <180 ml/m(2); P<0.05) were risk factors and predictors influencing hospital and late death. After the operation, the LV function improved significantly and the improvement was maintained at the mid-term period; the LV ejection fraction was 31.8+/-7.9% (P<0.01) at 1 year from 23.0+/-7.3% preoperatively, left ventricular diastolic diameter was 62.8+/-10.9 (P<0.01) from 81.7+/-8.2 mm and the LV endosystolic volume index was 88.5+/-45.8 (P<0.05) from 162.6+/-41.6 ml/m(2). CONCLUSIONS: The operative results improved with the selection of the procedures, with elective operation, and mitral plasty for less cardiac dilatation. The mid-term results of clinical status and LV function showed the effectiveness of the operation.     

Serial assessment of ventricular performance after valve replacement for aortic stenosis

The purpose of this investigation was to examine changes in cardiac function after aortic valve replacement in patients with chronic aortic stenosis. Eleven consecutive patients with severe aortic stenosis were studied by radionuclide angiocardiography before; after 1, 2, 4, 6, 8, and 18 to 24 hours; and late after operation. Measurements of cardiac output, mean systemic blood pressure, heart rate, and left ventricular ejection fraction were similar before and immediately after operation. Significant early changes were observed in pulmonary capillary wedge pressure (27 to 13 mm Hg; p less than 0.001), left ventricular end-diastolic volume (214 to 166 ml; p less than 0.01), pulmonary blood volume (700 to 462 ml/m2; p less than 0.01), and right ventricular ejection fraction (0.54 to 0.68; p less than 0.001). A radionuclide angiocardiogram acquired a mean of 3.5 months after operation revealed increased resting left ventricular ejection fraction (0.49 to 0.58; p = 0.05), decreased end-systolic volume (91 to 59 ml; p less than 0.05), and decreased end-diastolic volume (166 to 135 ml; p less than 0.02) compared with measurements before operation. Improved exercise tolerance occurred in nine patients. The significant change in function during the early period after valve replacement was a maintenance of baseline cardiac output at a reduced level of left ventricular filling. Several months after operation, left ventricular volumes decreased further, resting ventricular performance was improved, and improved maximal exercise function was demonstrated. These changes probably reflected morphologic normalization after aortic valve replacement.     

The cardiocirculatory and metabolic effects of endotoxin challenge after canine resuscitated hemorrhagic shock

Although adequate volume resuscitation has decreased mortality from hemorrhagic shock, recovery in many patients is complicated by sepsis. To determine whether a subject debilitated by hemorrhagic shock would exhibit greater cardiocirculatory dysfunction when challenged with sepsis, ten dogs (Group I) were hemorrhaged to a mean arterial blood pressure of 30 mm Hg. After 2 hours of hypotension, shed blood and lactated Ringer's solution (50 ml/kg) were given, and the dogs were observed for 3 to 6 days. Ten dogs were sham hemorrhage and served as controls (Group II). On the experimental day, all cardiovascular and hemodynamic parameters were measured in both groups of animals before endotoxin challenge. There was no significant difference in cardiac output, stroke volume, stroke work, +dP/dt max, myocardial blood flow, myocardial oxygen metabolism, or acid-base balance in the two groups. Compared to sham-hemorrhaged dogs, resuscitated shock dogs had a significantly lower mean arterial blood pressure (127 +/- 7 vs. 110 +/- 6 mm Hg; p less than 0.05), and heart rate was significantly higher (86 +/- 6 vs. 109 +/- 7 beats/minute; p less than 0.05). Furthermore, maximal rate of left ventricular pressure fall (-dP/dT max) was significantly lower in the animals previously hemorrhaged, suggesting a persistent defect in left ventricular relaxation. Blood glucose and insulin levels were significantly elevated in the resuscitated shocked dogs, likely due to increased circulating catecholamine concentrations and enhanced glycogenolysis. Endotoxin shock caused significant hypotension, acidosis, and impaired regional perfusion in all dogs. In addition, cardiac output, stroke volume, dP/dT, and left ventricular end-diastolic pressure fell and hyperglycemia and hyperinsulinemia occurred in all dogs after endotoxin injection.(ABSTRACT TRUNCATED AT 250 WORDS)     

Noninvasive assessment of hemodynamic effects of mitral valve commissurotomy during rest and exercise in patients with mitral stenosis.

Noninvasive radionuclide angiocardiography (RNA) provides simple and accurate assessment of parameters of cardiac function during rest and during maximal exercise. Left ventricular function was assessed by RNA in nine patients with isolated mitral stenosis before and approximately 6 months after mitral commissurotomy. Before operation, the mean mitral valve gradient was 14.0 +/- 2.8 mm Hg, and the mean mitral valve area was 1.20 +/- 0.3 cm2. Each patient was evaluated at rest and during maximal exercise on an isokinetic bicycle ergometer before and after commissurotomy. Heart rate, ejection fraction, end-diastolic volume, stroke volume, pulmonary transit time, cardiac output, and diastolic ventricular filling rate were determined by the radionuclide technique. Before operation, patients with mitral stenosis had characteristic changes from rest to exercise which supported restriction to diastolic ventricular filling as the primary limitation in generating a cardiac output during exercise. The stroke volume was unchanged from rest to exercise. Thus the cardiac output during exercise was heart rate dependent. However, after commissurotomy the stroke volume increased from rest to exercise. Therefore, cardiac output during exercise was achieved by heart rate and an augmented stroke volume. Moreover, the pulmonary transit time was reduced during rest and exercise after operation. The maximum ventricular ejection and filling rates were markedly increased during rest and exercise after commissurotomy. These differences in hemodynamic parameters at rest and during exercise document the mechanics of increased exercise tolerance in patients with mitral stenosis after mitral commissurotomy.     

Comparison of tidal ventilation and high-frequency jet ventilation before and after cardiopulmonary bypass in dogs using two-dimensional transesophageal echocardiography

This study compared the use of high-frequency jet ventilation (HFJV) and tidal ventilation (TV) in a group of dogs with induced global myocardial ischemia before and after cardiopulmonary bypass. Transesophageal echocardiography was used to determine whether HFJV with its lower airway pressures could improve cardiac performance. The surgical procedure was separated into four study periods: closed chest before bypass, open chest before bypass, open chest after bypass, and closed chest after bypass. During each of these study periods, the dogs were randomly ventilated with alternate periods of TV and HFJV to maintain the PaCO2 at 34.3 +/- 3.3 mm Hg (mean +/- SEM). Cardiac output, stroke volume, systemic mean blood pressure, left ventricular ejection fraction, left ventricular end-diastolic volume, left ventricular dP/dt, left ventricular stroke work, and expiratory volumetric flows were higher during HFJV, whereas airway pressures and pulmonary vascular resistance were lower. Increases in cardiac output and stroke volume during HFJV were due to a combination of improved left ventricular contractility indicated by increased LV dP/dt and increased left ventricular end-diastolic volume accompanying decreased airway pressures. These data indicate that HFJV with its lower airway pressure is associated with significantly less impairment of cardiovascular function than TV in dogs with induced global myocardial ischemia.