End-systolic Meridional Wall Stress Research Articles

Haemodynamic effects of a left stellate ganglion block in ASA I patients. An echocardiographic study.

In anaesthetized dogs, stellate ganglion blockade led to a moderate disturbance in left ventricular diastolic function. We investigated the effect of a left-sided block, following injection of 10 mL bupivacaine 0.5%, on echocardiographic variables of ventricular function in eight otherwise healthy patients with sympathetically mediated pain syndromes. After the blockade, heart rate (control: 66+/-3 (mean+/- SEM), block: 64+/-3 min-1) and mean arterial blood pressure (88.5+/-6.0 vs. 84.0+/-8.1 mmHg) were unchanged, but afterload decreased (end-systolic meridional wall stress; 69.6+/-9.9 vs. 59.8+/-7.1, P < 0.05). Stroke volume increased from 71.2+/-8.1 to 79.6+/-7.4 mL, P < 0.05. Variables of systolic function were unchanged, but relaxation was prolonged (isovolumic relaxation time; 71+/-5 vs. 81+/-4 ms, P < 0.05). In patients who were ASA I, there was a small impairment in echocardiographic variables during ventricular relaxation after a left stellate ganglion blockade. This small effect did not compromise ventricular function, and the heart responded with a small stroke volume increase to the simultaneous afterload reduction.

Refractory Hypotension After Induction of Anesthesia in a Patient Chronically Treated with Angiotensin Receptor Antagonists

Refractory Hypotension After Induction of Anesthesia in a Patient Chronically Treated with Angiotensin Receptor Antagonists

The influence of low afterload on the nature of the stress-velocity relationship

OBJECTIVESCorrect assessment of contractility by conventional methods during manipulation of afterload is often disappointing. To this purpose, the stress-velocity relationship offers assessment of contractility at different levels of afterload. We decided to study the influence of afterload on the nature of the stress-velocity relation.BACKGROUNDAlthough linear at baseline conditions in a population older than two years, data in newborns or after administration of low-dose dobutamine suggest a different nature of this relationship at low afterload.METHODSTen healthy piglets (five to six weeks; 11 to 13 kg) were studied. End-systolic meridional wall stress (ESWS) and rate-corrected velocity of circumferential fiber shortening (VcFc) were measured in these piglets at baseline, after balloon occlusion of the descending aorta, and at nitroprusside infusion rates of 1, 2 and 5 μg/kg/min. To eliminate inotropic influences mediated by reflex tachycardia, we subsequently studied five piglets and six adult pigs after bilateral cervical vagotomy.RESULTSThe ESWS changed from a baseline mean of 50 g/cm2to 137 g/cm2after balloon occlusion and to 19 g/cm2at 5 μg/kg/min of nitroprusside. The VcFc changed from 1.19 c/s (circumference/second) to values of 0.9 c/s and 1.73 c/s, respectively. The ensuing stress-velocity regression line proved to be curvilinear instead of linear. The steeper slope at low afterload could suggest enhanced contractility compared to expected values had the relationship been linear.CONCLUSIONSData from young piglets and adult pigs suggest a curvilinear relationship of the stress-velocity relationship. This could probably explain some of the “hypercontractile states” encountered in conditions with low afterload.

Assessment of the functional status of heart failure in non ischemic dilated cardiomyopathy: an echo-dobutamine study.

The functional status of heart failure (HF) is conventionally evaluated by peak exercise oxygen consumption (VO2 max). Dobutamine echocardiography can be used to evaluate myocardial reserve. The aim of this study was to estimate the functional status of chronic HF in patients with dilated cardiomyopathy, by investigating the changes in echo-variables, as assessed by echo-dobutamine, in relation with VO2 max. A low infusion rate echo-dobutamine test (10 micrograms/kg/min) was performed in 30 patients with dilated cardiomyopathy and 1 h later VO2 max was measured. VO2 max (ranging from 7.6 to 23 ml/kg/min, mean 14.06 +/- 0.64 ml/kg/min) was correlated with the changes (values obtained after inotropic stimulation minus those obtained at baseline) in left ventricular end-systolic diameter (r:0.80, p:0.001), in left ventricular end-systolic posterior wall thickness (r:0.73, p:0.001) and in left ventricular heart-rate corrected mean velocity of circumferential fiber shortening (Vcfc)/end-systolic meridional wall stress ratio (r:0.64, p:0.0001). A negative correlation was found between VO2 max and the changes in end-systolic meridional wall stress (r: -0.76, p:0.001). After dobutamine infusion Vcfc/systolic meridional wall stress ratio increased in patients with VO2 max > 14 ml/kg/min but decreased in patients with VO2 max < 14 ml/kg/min (0.0001 +/- 0.0001 vs -0.0002 +/- 0.0003 circ x cm2/g x s, p:0.0001). End-systolic meridional wall stress was decreased in patients with VO2 max > 14 ml/kg/min but increased in patients with VO2 max < 14 ml/kg/min (-126.97 +/- 34.24 vs 205.77 +/- 56.71 g/cm2, p:0.0001). The changes in echo-variables assessed by echo-dobutamine are well correlated with VO2 max and seem to be accurate for evaluating the functional status of chronic HF in patients with dilated cardiomyopathy.

Contractility in humans after coronary artery surgery.

Propofol's unique pharmacokinetic profile offers advantages for titration and rapid emergence in patients after coronary artery bypass graft (CABG) surgery, but concern for negative inotropic properties potentially limits its use in these patients. The current study analyzed the effect of various propofol plasma concentrations on left ventricular (LV) contractility by means of a single-beat contractile index based on LV maximal power (PWR(max)). The study was conducted in 30 patients after CABG surgery. Immediately after admission to the intensive care unit (ICU), four different plasma concentrations of propofol 0.65, 1.30, 1.95, and 2.60 microg/ml were established. At each concentration level, the cardiac and vascular effects of propofol were studied by combining echocardiographic data with invasively derived aortic root pressure. Preload was characterized by LV end-diastolic dimensions. Afterload was indicated in terms of indexed systemic vascular resistance (SVRI), LV end-systolic meridional wall stress (LV-ESWS), and arterial elastance (Ea). Quantification of effects on contractility was achieved by preload-adjusted PWRmax. Myocardial contractility did not change during a fourfold increase in propofol plasma concentration. Preload-adjusted PWRmax amounted to 3.90+/-1.75 W x ml(-2) x 10(4), 3.98+/-1.69, 3.94+/-1.70, and 3.88+/-1.72, respectively (mean+/-SD). With respect to ventricular loading conditions, propofol caused a significant reduction in both pre- and afterload. The current results strongly suggest that propofol lacks direct cardiac depressant effects. Nevertheless, meaningful vascular actions of propofol could be demonstrated. Significant decreases in ventricular loading conditions accounted for a marked decrease in arterial blood pressure and supported the concept that propofol in clinically relevant concentration is a vasodilator.

Beat-to-beat Augmentation of Left Ventricular Function by Intraaortic Counterpulsation

Measuring the effects of intraaortic balloon counterpulsation (IABP) in single cardiac beats may permit an improved understanding of the physiologic mechanisms by which IABP improves the circulation. The objective of the study was to use trans- esophageal echocardiography in combination with hemodynamic measurements to test the hypothesis that IABP improves global left ventricular systolic function selectively in the IABP-augmented cardiac beats by acutely decreasing left ventricular afterload. Twenty-seven studies in which the IABP-to-R wave trigger ratio was serially changed from 1:1, 1:2, 1:4, 0:1 (IABP off) and back to 1:1 were performed in 20 anesthetized cardiac surgical patients during IABP support. Left ventricular short-axis end-diastolic cross-sectional area, end-systolic area, mean end-systolic wall thickness, and ejection time were measured by transesophageal echocardiography at the midpapillary muscle level. Aortic pressure was measured simultaneously from the central lumen of the intraaortic balloon catheter. These measurements were used to calculate the fractional area change, end-systolic meridional wall stress, and heart rate-corrected velocity of circumferential fiber shortening. The echocardiographic and hemodynamic parameters of left ventricular preload, afterload, and systolic function immediately after balloon deflation (IABP-augmented cardiac beats) were compared to the parameters measured during nonaugmented cardiac beats to determine the beat-to-beat effects of IABP on left ventricular function. IABP-augmented cardiac beats had a decreased systolic arterial pressure and end-systolic meridional wall stress and increased diastolic blood pressure, fractional area change, and velocity of circumferential fiber shortening compared to nonaugmented cardiac beats. IABP did not cause significant beat-to-beat changes in heart rate, pulmonary artery diastolic pressure, or central venous pressure. The improvement in left ventricular systolic function associated with IABP-augmented cardiac beats correlated with the decrease in end-systolic meridional wall stress for that cardiac beat. Beat-to-beat echocardiographic and hemodynamic measurements performed in anesthetized cardiac surgical patients during IABP support demonstrated improved left ventricular systolic function and decreased left ventricular systolic wall stress in the cardiac beats immediately after balloon deflation. The relationship between left ventricular systolic function and left ventricular systolic wall stress during IABP support suggests that afterload reduction was an important mechanism by which IABP instantaneously improved circulatory function in anesthetized cardiac surgical patients.

Depression of cardiac function after deep hypothermic circulatory arrest in deeply anesthetized neonatal lambs

Cardiac dysfunction is common after neonatal cardiac operations. Previous in vivo studies in neonatal animal models however, have failed to demonstrate decreased left ventricular function after ischemia and reperfusion. Cardiac dysfunction may have been masked in these studies by increased endogenous catecholamine levels associated with the use of light halothane anesthesia. Currently, neonatal cardiac operations are often performed with deep opiate anesthesia, which suppresses catecholamine surges and may affect functional recovery. We therefore examined the recovery of left ventricular function after ischemia and reperfusion in neonatal lambs anesthetized with high-dose fentanyl citrate (450 μg/kg administered intravenously). Seven intact neonatal lambs with open-chest preparation were instrumented with left atrial and left ventricular pressure transducers, left ventricular dimension crystals, and a flow transducer. The lambs were cooled (<18º C) on cardiopulmonary bypass (22 ± 6 minutes), exposed to deep hypothermic circulatory arrest (46 ± 1 minutes), and rewarmed on cardiopulmonary bypass (30 ± 10 minutes). Catecholamine levels and indexes of left ventricular function were determined before (baseline) and 30, 60, 120, 180, and 240 minutes after termination of cardiopulmonary bypass. Levels of epinephrine, norepinephrine, and dopamine were unchanged from baseline values. Left ventricular contractility (slope of end-systolic pressure-volume relationship) was depressed from baseline value (31.7 ± 9.3 mm Hg/ml) at 30 minutes (15.7 ± 6.4 mm Hg/ml) and 240 minutes (22.7 ± 6.4 mm Hg/ml) but unchanged between 60 and 180 minutes. Left ventricular relaxation (time constant of isovolumic relaxation) was prolonged from baseline value (19.0 ± 3.0 msec) at 30 minutes (31.4 ± 10.0 msec) and 240 minutes (22.1 ± 2.8 msec) but unchanged between 60 and 180 minutes. Afterload (left ventricular end-systolic meridional wall stress) was decreased at 30, 60, and 240 minutes. Indexes of global cardiac function (cardiac output, stroke volume), preload (end-diastolic volume), and left ventricular compliance (elastic constant of end-diastolic pressure-volume relationship) were unchanged from baseline values. In deeply anesthetized neonatal lambs exposed to ischemia and reperfusion, left ventricular contractility, relaxation, and afterload are markedly but transiently depressed early after reperfusion and mildly depressed late after reperfusion. (J T HORAC C ARDIOVASC S URG 1996;111:359-66)

Left ventricular mechanics after early successful repair of aortic coarctation

SummaryA successful aortic coarctectomy performed beyond early infancy is followed, even in the long term, by persistence of left ventricular hypertrophy and by diastolic dysfunction, although systolic function is often increased. In this study we investigated whether earlier coarctectomy provides better preservation of left ventricular function. Experimental studies on the myocardial response to pressure overload show that neonates and young infants develop a functionally advantageous combination of myocytic hyperplasia (together with mild hypertrophy) and increased angiogenesis. Older patients, in contrast, generate myocytic hypertrophy in isolation, setting the scene for ventricular dysfunction. Cross-sectional echo-Doppler evaluation of left ventricular size, shape, mass and systolic and diastolic function was made in 13 patients a mean of 44±36 months (range 11 days-10 years) after successful coarctectomy in the first year of life. They were compared to 11 age, body surface area and gender-matched control subjects. In all patients, left ventricular mass normalized for body surface area was significantly greater than in the control group (66.2±12.3 vs 43±l2 p=0.0001). There was no correlation between left ventricular mass normalized for body surface area and age at operation, follow-up duration, degree of residual isthmic gradient, peak systolic wall stress, systolic blood pressure or left ventricular shape. No significant differences were noted between the two groups in regard to transverse diameter of the aortic arch, left ventricular afterload (meridional end-systolic wall stress), volume and shape (both in systole and diastole), systolic performance (fractional shortening and ejection fraction) and contractility (rate-corrected velocity of fiber shortening to meridional end-systolic wall stress relationship). Furthermore, no significant differences were found with respect to indices of mitral (including peak filling rate normalized to mitral stroke volume) and pulmonary venous flow, suggesting normal diastolic function. Repair of aortic coarctation in the first year of life promotes a more complete recovery of left ventricular function (particularly diastolic) than that reported after coarctectomy at older age, despite persistence of moderate ventricular hypertrophy.

Left ventricular contractile state of early human neonates with patent ductus arteriosus.

Using echocardiographic technique, we studied the left ventricular (LV) contractile state in 32 full-term infants within 24 hr after birth. They were divided into 2 groups based on the timing of the examinations; the group 1 (n = 17), < 3 hr after birth; the group 2 (n = 15), > 3 and < 24 hr after birth, and the additional examinations were performed on day 5. The patency of the ductus arteriosus and its internal diameter were determined by pulsed Doppler and two-dimensional echocardiography. The left atrial to aortic root ratio was obtained from M-mode echocardiography, and the LV contractile state was estimated by the relationship between heart rate-corrected velocity of circumferential fiber shortening (mVcfc) and end-systolic meridional wall stress (ESS). The ductus arteriosus was open in all cases of group 1 and in 83% of the cases of group 2, but the ductal diameter and the left atrial to aortic root ratio significantly decreased in group 2. The relationship between mVcfc and ESS showed no significant differences between 2 groups and the control. Afterload, represented as ESS, was significantly lower in group 1 than the control. We suggest that the low afterload condition helps the adequate LV contraction even under the increased preload through the left-to-right ductus arteriosus shunting after birth.

Natural history and patterns of recovery of contractile function in single left ventricle after Fontan operation.

Before the era of the Fontan procedure, the typical course of patients with single left ventricle (LV) consisted of heart failure and death during the second or third decade of life. Despite the advent of effective palliative therapy, ventricular dysfunction remains a significant clinical problem for these patients. To investigate the causes of ventricular dysfunction in these patients and to determine whether Fontan-type repair reverses deterioration of LV function, the ventricular dimensions, volume, shape, wall stress, and systolic function were determined by echocardiography in 84 patients 0.2-35 years old with double-inlet single LV or tricuspid atresia. Measurements were obtained in 67 patients after palliation (arterial shunt or pulmonary artery band) and in 47 patients a median of 4.4 years after a Glenn (n = 9) or a Fontan operation (n = 38). Before a Fontan procedure, ventricular volumes were 2 to 3 times normal. Ventricular afterload, assessed as circumferential and meridional end-systolic wall stress, became abnormal after 2 years of age. With age, LV shape changed progressively from ellipsoidal to spherical, as indicated by the decrease in long axis:short axis ratio from normal (1.9) toward unity. Concomitantly, the ratio of circumferential to meridional end-systolic wall stress fell from 1.3 to unity, the ratio of a sphere at equilibrium. This age-related change in shape and load occurred in concert with progressive deterioration of LV systolic function and contractility. Aortic oxygen saturation, an indicator of pulmonary blood flow and therefore volume work in single-ventricle physiology, was inversely and independently correlated with contractility. In the group of patients in whom a Glenn or a Fontan operation was performed at < 10 years of age, ventricular dimensions, volumes, and wall stress diminished and LV function and contractility improved after surgery (p < 0.001). In patients undergoing surgery after 10 years of age, few had improvement of LV function after surgery. Postoperative ventricular function and contractility were inversely related to age at surgery and to aortic oxygen saturation measured before surgery. Although Fontan-type repair of single ventricle early in life is associated with reversal of the abnormal contractile mechanics associated with age and volume load, this capacity for recovery diminishes with age at surgery.

Histamine decreases left ventricular contractility in normal human subjects.

To determine whether histamine alters human left ventricular contractility we measured heart rate, calibrated carotid arterial pressure, and left ventricular dimensions (echocardiogram) in nine healthy volunteers. We assessed baseline contractility using the end-systolic pressure-dimension relationship and the end-systolic meridional wall stress-rate-corrected velocity of circumferential fiber shortening relationship determined over a wide range of afterloads using phenylephrine and nitroprusside infusions. We then infused histamine for 3-5 min at a dose predetermined to decrease mean arterial pressure by 20%, both before and after H1 receptor antagonist pretreatment (diphenhydramine 50 mg i.v.). Histamine decreased end-systolic pressure but, unlike an equally hypotensive infusion of nitroprusside, did not decrease end-systolic dimension or increase fractional shortening. Histamine also decreased velocity of circumferential fiber shortening at the same end-systolic meridional wall stress as controls (P < 0.05). These effects of histamine were inhibited by H1 antagonist pretreatment. We conclude that the dominant effect of histamine on the human heart is to decrease left ventricular contractility and that this decrease in contractility is dependent, at least partially, on H1-receptor activation.

Dobutamine stress echocardiography: A sensitive indicator of diminished myocardial function in asymptomatic doxorubicin-treated long-term survivors of childhood cancer

Doxorubicin is an effective anticancer chemotherapeutic agent known to cause acute and chronic cardiomyopathy. To develop a more sensitive echocardiographic screening test for cardiac damage due to doxorubicin, a cohort study was performed using dobutamine infusion to differentiate asymptomatic long-term survivors of childhood cancer treated with doxorubicin from healthy control subjects. Echocardiographic data from the experimental group of 21 patients (mean age 16 ± 5 years) treated from 1.6 to 14.3 years (median 5.3) before this study with 27 to 532 mg/m2of doxorubicin (mean 196) were compared with echocardiographic data from 12 normal age-matched control subjects. Graded dobutamine infusions of 0.5, 2.5, 5 and 10 μg/kg per min were administered. Echocardiographic Doppler studies were per formed before infusion and after 15 min of infusion at each rate. Dobutamine infusion at 10 μg/kg per min was discontinued after six studies secondary to a 50% incidence rate of adverse symptoms.The most important findings were that compared with values in control subjects, end-systolic left ventricular posterior wall dimension and percent of left ventricular posterior wall thickening in doxorubicin-treated patients were decreased at baseline study and these findings wert more clearly delineated with dobutamine stimulation. End-systolic left ventricular posterior wall dimension at baseline for the doxorubicin-treated group was 11 ± 1.9 mm versus 13.1 ± 1.5 mm for control subjects (p < 0.01). End-systolic left ventricular posterior wall dimension at the 5- μg/kg per min dobutamine infusion for the doxorubicin-treated group was 14.1 ± 2.4 mm versus 19.3 ± 2.6 mm for control subjects (p < 0.01). Percent left ventricular posterior wall thickening at baseline for the doxorubicin-treated group was 78 ± 18% versus 97 ± 13% for the control group (p < 0.01). Percent left ventricular posterior wall thickening at the 5- μg/kg per min dobutamine infusion for the doxorubicin-treated group was 121 ± 37% versus 185 ± 20% for the control group (p < 0.01). Decreased left ventricular shortening fraction and increased left ventricular end-systolic meridional wall stress were demonstrated in doxorubicin-treated patients only during dobutamine infusion. No differences were found between results in control subjects and doxorubicin-treated patients for measured diastolic variables.Thus, asymptomatic long-term survivors of childhood cancer treated with doxorubicin may have latent decreased cardiac performance that is undetected by commonly used echocardiographic methods, including rest left ventricular shortening fraction and left ventricular end-systolic meriodional wall stress. Our data establish that evaluation of left ventricular systolic function by end-systolic posterior wall dimension, posterior wall thickening, end-systolic meridional wall stress and shortening fraction measured during inotropic stimulation with dobutamine provides a sensitive technique for examining the cardiac status of asymptomatic doxorubicin-treated patients.

Effect of peripheral cardiopulmonary bypass on left ventricular size, afterload and myocardial function during elective supported coronary angioplasty

Although cardiopulmonary bypass support has been increasingly used for high risk coronary angioplasty, few data exist regarding its effects on left ventricular function. Accordingly, in 20 patients changes in left ventricular size, afterload and myocardial function were assessed by continuous hemodynamic monitoring and simultaneous two-dimensional echocardiography during cardiopulmonary bypass-supported high risk angioplasty.The cross-sectional left ventricular area during bypass support remained unchanged during diastole, whereas during systole it decreased (from 29.6 ± 11.4 to 27.6 ± 10.4 cm2, p < 0.05). Global left ventricular function expressed as fractional area change remained unchanged from baseline to bypass support but decreased during balloon inflation (from 0.27 ± 0.11 to 0.17 ± 0.09, p < 0.001). The end-systolic meridional wall stress decreased during bypass support (from 141 ± 75 to 110 ± 58 × 103dynes/cm2, p < 0.02). Regional myocardial function was assessed by a wall motion score (0 = normal, 1 = hypokinesia, 2 = akinesia and 3 = dyskinesia). Regions supplied by a stenotic (≥ 50% diameter) vessel deteriorated during bypass support (score from 0.9 ± 0.8 to 1.06 ± 0.8, p < 0.01), whereas regions supplied by a nonslenotic vessel did not. Regions supplied by the target vessel deteriorated further during balloon inflation (score from 0.7 ± 0.6 to 1.7 ± 0.75, p < 0.001).Thus, although left ventricular size and global function remain unchanged and afterload decreases during bypass support, myocardial dysfunction in regions supplied by a stenotic vessel may occur. Furthermore, regional and global left ventricular dysfunction still occur with angioplasty balloon inflation during cardiopulmonary bypass support.

Physiologic Assessment of Milrinone Therapy in Severe Heart Failure Patients

To assess the inotropic, vasodilator, and after-load-reducing effects of intravenous milrinone in patients with severe congestive heart failure, a simple noninvasive echocardiographic study coupled with a right catheterization was performed in 12 patients. Milrinone was administered intravenously as a 50 micrograms.kg-1 bolus followed by a 24-h milrinone infusion at a rate of 0.5 mg.kg-1.min-1 [corrected]. Echocardiographic left ventricular end-diastolic diameter (Ded), end-systolic diameter (Des), and wall thickness were measured at baseline and at 24 h of milrinone infusion, before and after a sublingual nitrate administration (0.8 mg of nitroglycerin) that induced load variations. Hemodynamic measurements were performed simultaneously. Left ventricular end-systolic meridional wall stress (Ses) was then calculated. The slopes of percent fractional shortening (percent FS)/Ses and Ses/Des, obtained during sublingual nitrate administration, were traced. Both end-systolic relations are an index of the contractile state. Milrinone therapy improved hemodynamics in all patients, resulting in stabilized hemodynamic conditions between 12 and 24 h of continuous milrinone infusion. At these times, the cardiac index increased to 30% while the capillary pulmonary wedge pressure and systemic vascular resistance decreased to 26 and 24%, respectively (all p less than 0.01). The average slope of Ses/Des shifted upward from 47.5 +/- 30 to 69.25 +/- 34 (p less than 0.05) and the average slope of (percent FS)/Ses shifted from -0.032 +/- 0.025 to -0.082 +/- 0.061 (p less than 0.01), both variations attesting the inotropic effect of milrinone.(ABSTRACT TRUNCATED AT 250 WORDS)

Early and late changes in left ventricular systolic performance after percutaneous aortic balloon valvuloplasty

To evaluate early and late hemodynamics after aortic valvuloplasty, 17 patients underwent first-pass radionuclide angiocardiography with simultaneous high-fidelity micromanonteter pressure before, 10 minutes after and 6 months after aortic valvuloplasty. Pressure-volume and stress data were assessed. Immediately after the procedure, no significant change was observed in heart rate, systemic blood pressure, cardiac output or aortic insufficiency (as measured by visual or quantitative aortography). The mean and peak transvalvular gradient decreased from 64 to 36 mm Hg (p < 0.001) and 76 to 38 mm Hg (p < 0.001), respectively. The mean aortic valve area increased from 0.5 to 0.8 cm 2 (p < 0.001). Using echocardiography, meridional end-systolic wall stress decreased from 81 to 63 · 10 3 dynes/cm 2 (p < 0.001). Left ventricular ejection fraction increased from 0.48 to 0.54 (p < 0.01), end-diastolic volume decreased from 161 to 143 ml (p < 0.001) and end-diastolic pressure decreased from 18 to 13 mm Hg (p < 0.01). Left ventricular stroke work (the area of the pressure-volume loop) also decreased from 17.5 to 14.7 · 10 6 ergs (p < 0.001). The loop shifted to the left and downward. At the 6-month study, the mean and peak aortic valve gradient increased from 36 to 56 mm Hg (p < 0.001) and 38 to 61 mm Hg (p < 0.001), respectively. The aortic valve area worsened (0.8 to 0.5 cm 2, p < 0.001), end-systolic wall stress increased (63 to 84 · 10 3 dynes/cm 2, p < 0.001) and the left ventricular ejection fraction decreased (0.54 to 0.49, p < 0.02). The end-diastolic volume increased (143 to 159 ml) along with the end-diastolic pressure (13 to 21 mm Hg, p < 0.01). Left ventricular stroke work (14.7 to 16.3 · 10 6 ergs) was not different from baseline. The loop returned toward baseline. The changes seen in ejection fraction, however, were primarily related to changes in loading conditions. At 6 months, restenosis occurred in most patients, but was not always accompanied by a worsening of clinical status. The pressure-volume loop shifted back toward baseline and the ejection fraction decreased as end-systolic stress increased. There were little data to support an intrinsic change in myocardial contractile performance at any postprocedural interval after aortic valvuloplasty. Rather, the changes in ejection dynamics appeared primarily to be a function of altered loading conditions.

Left ventricular filling in dilated cardiomyopathy: Relation to functional class and memodynamics

Left ventricular systolic function does not correlate well with functional class in patients with dilated cardiomyopathy. To determine whether the correlation is better with Doppler indexes of left ventricular diastolic function, 34 patients with dilated cardiomyopathy (M-mode echocardiographic end-diastolic dimension greater than 60 mm, fractional shortening less than 25%, increased E point-septal separation) were studied. Patients were classified into two groups according to functional class. Group 1 consisted of 16 patients in New York Heart Association functional class I or II; group 2 included 18 patients in functional class III or IV. Left ventricular dimensions, fractional shortening, left ventricular mass, meridional end-systolic wall stress, peak early and late transmitral filling velocities and their ratio, isovolumetric relaxation period and time to peak filling rate were computed from pulsed wave Doppler and M-mode echocardiograms and calibrated carotid pulse tracings. Right heart catheterization was performed in 20 of 34 patients. No differences were observed between groups with regard to age, gender distribution, heart rate, blood pressure and M-mode echocardiographic-derived indexes of systolic function. Peak early filling velocity (72 +/- 13 versus 40 +/- 10 cm/s, p less than 0.001) was higher and atrial filling fraction (27 +/- 4% versus 46 +/- 8%, p less than 0.001) was lower in group 2 than in group 1. The ratio of early to late transmitral filling velocities was higher in group 2 patients (2.3 +/- 0.5 versus 0.7 +/- 0.2, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Changes in left ventricular systolic performance immediately after percutaneous aortic balloon valvuloplasty

To evaluate the acute changes in left ventricular (LV) performance before and immediately after percutaneous aortic valvuloplasty, 25 patients underwent first-pass radionuclide angiocardiography for construction of pressure-volume loops. Simultaneously, high-fidelity micromanometric aortic and LV pressures were recorded. Echocardiographic wall thickness was used to define wall stress. After valvuloplasty, no acute changes were observed in the heart rate, aortic systolic pressure, cardiac output or degree of aortic insufficiency. Valvuloplasty decreased the peak aortic valve gradient from 73 to 40 mm Hg (p < 0.001) and the mean gradient from 61 to 30 mm Hg (p < 0.001); aortic valve area increased from 0.55 to 0.80 cm 2 (p < 0.001). Meridional end-systolic wall stress decreased from 83 to 55 × 10 3 dynes/cm 2 (p < 0.01). LV ejection fraction increased from 0.41 to 0.48 (p < 0.01). LV end-diastolic volume decreased from 186 to 160 ml (p < 0.001), end-systolic volume decreased from 115 to 87 ml (p < 0.001) and end-diastolic pressure decreased from 22 to 17 mm Hg (p < 0.01). LV stroke work decreased from 16.0 to 14.0 × 10 6 erg (p < 0.001). No change was observed in peak positive LV sol dP dt or the end-systolic pressure-volume ratio. This study documents variable and complex changes in the measures of cardiac function after aortic valvuloplasty. A decrease in the amount of LV outflow obstruction with maintenance of the cardiac output at a decreased level of LV filling occurs.

Does Anesthetic Technique Make a Difference? Augmentation of Systolic Blood Pressure During Carotid Endarterectomy

SMITH, J. S.; ROIZEN, M. F.; CAHALAN, M. K.; BENEFIEL, D. J.; BEAUPRE, P. N.; SOHN, Y. J.; BYRD, B. F.; SCHILLER, N. B.; STONEY, R. J.; EHRENFELD, W. K.; ELLIS, J. E.; ARONSON, S. Author Information

Right and left ventricular performance during and after abdominal aortic aneurysm repair.

To evaluate the effect of aortic occlusion and limb reperfusion on global and regional function of the right and left ventricle during infrarenal abdominal aortic aneurysm repair, 23 patients underwent five intraoperative first-pass radionuclide angiocardiograms: 1) before the skin incision, 2) at aortic cross-clamp, 3) 20 minutes after aortic occlusion, 4) at unclamping, and 5) after skin closure. A subset of twelve patients had simultaneous transesophageal echocardiography to evaluate left ventricular wall stress. Parameters measured included the electrocardiogram (ECG), heart rate, blood pressure, pulmonary artery pressure, the cardiac output, the left and right ventricular ejection fractions, left ventricular volumes, and left ventricular wall stress. Significant changes (p less than 0.01) were observed at aortic clamping in the left ventricular ejection fraction (from 0.56 to 0.48), end-diastolic volume (from 171 to 225 ml), end-systolic volume (from 85 to 127 ml), mean blood pressure (from 82 to 91 mmHg), and meridional end-systolic wall stress (from 53 to 67 10(3) dyne/cm2). Once the clamp was removed, significant variations were seen in the left ventricular ejection fraction (from 0.51 to 0.58), end-diastolic volume (from 205 to 187 ml), end-systolic volume (from 105 to 94 ml), mean blood pressure (from 84 to 69 mmHg), and meridional end-systolic wall stress (from 67 to 46 10(3) dyne/cm2). No differences were observed between the two aortic occlusion studies, and the baseline level of function was recovered in all parameters during the last study. These data quantify the changes in heart function that occur during abdominal aortic aneurysm operation and demonstrate that the majority of the adaptations that occurred were due to a variation in afterload.

A hyperkinetic heart in uncomplicated active acromegaly. Explanation of hypertension in acromegalic patients?

Cardiac function was studied by echocardiography in 12 patients with active acromegaly and in 12 age- and sex-matched healthy control subjects. None of the patients had cardiovascular diseases or other endocrine diseases than acromegaly. The patients had a mean age of 39 +/- 5 years and were short-term acromegalic with a mean duration of disease of 6 +/- 3 years. Mean left ventricular mass was 163 +/- 43 g/m2 in the acromegalic group versus 120 +/- 24 g/m2 in the control group. Preload (the diastolic diameter of the left ventricle) was within normal limits, while afterload (end-systolic meridional wall stress) was significantly decreased in the acromegalic group. Myocardial contractility assessed as fractional shortening of the left ventricle was 39.9 +/- 3.6% in the acromegalic group versus 32.9 +/- 5.1% in the control group, and cardiac output was increased by 52% in the acromegalic group because of increased heart rate and stroke volume. We suggest that augmented peripheral blood flow is responsible for the condition of cardiac hyperkinesia in short-term acromegaly and involved in the development of hypertension, which is a frequent complication of long-term acromegaly.