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Increased left ventricular wall stress with pneumoperitoneum in obese females undergoing laparoscopic surgery
Al@j
48th Annual
Scientific
Meeting
Heart,
of CSANZ
INCREASED LEFT VENTRICULAR WALL STRESS WITH PNEUMOPERITONEUM IN OBESE FEMALES UNDERGOING LAPAROSCOPIC SURGERY D I Prior*. J SD una. J D Thomas. D G. l&h&& The Cleveland Clinic Foundation, ClevelaLd, OH, USA.
AAEMODYNAMIC EVIDENCE OF A DISPARITY DIASTOLIC DYSFUNCTION IN HYPERTENSION. &$Javward*. W.V. Kalnins., Department, St Vincent’s Hospital, Sydney, NSW.
2000; 9
1Department of Physiology and Pharmacology, The University of Queensland and the ZEchocardiographic Laboratory, The Prince Charles Hospital, Brisbane, Australia. Thyroid dysfunction often presents with marked cardiovascular symptoms tachycardia with high output failure in hyperthyroidism and bradycardia in hypothyroidism. This project assessed the changes in cardiac function noninvasively in chronically hyperthyroid or hypothyroid rats using high frequency, high frame rate echocardiographic imaging. Methods: 11 male Wistar rats (8 weeks old) were given triiodothyronine (T3; 0.05 m&g/day SC for 8 weeks) and measured after 0,4 and 8 weeks. To induce hypothyroidism, methimazole (500 mgfi drinking water) was given to 7 rats from day 18 of gestation until 6 months of age. Left parastemal and left apical echocardiographic images were obtained using the Hewlett Packard Sonos 5500 (12 Mhz frequency transducer) at an image depth of 3 cm using two focal zones. Left ventricular M-mode measurements at the level of fhe papillary muscles included left ventricular end-diastolic dimension (LVEDD), end-systolic dimension (LVESD), posterior wall in diastole (LVPWd) and fractional shortening (FS%). Pulsed-wave Doppler velocities were measured in the ascending and descending aorta and across the mitral valve; *p
IN THE DEGREE WOMEN WITH Cardiology
Women are more likely to develop left ventricular hypertrophy and diastolic heart failure in response to hypertension than men. Seventy percent of patients with hypertensive hypertrophic cardiomyopathy are women. We examined diastolic LV function using pressure-volume (PV) loops obtained by simultaneous micromanometer pressure and conductance catheter volume recordings in 8 postmenopausal hypertensive women with normal systolic function at routine coronary angiography. Passive diastolic function was defined by end-diastolic PV relations (EDPVR) during intermittent IVC occlusion, and active diastolic function by time constant of relaxation, Tau, and rate of pressure decline, dP/dt,,,,,. In 4 of the women, resting LVEDP was significantly greater compared to the remainder (17+1 vs 9flmmHg, pcO.01, meanBEM). These women were also character&d by smaller indexed LV volumes when compared to the 4 remaining hypertensive women (49f3 vs 59+3 mL/m’, p=O.O4). Despite these differences, systolic pressure (16ti6 vs 159fllmmHg) and duration of hypertension (14_+7 vs 11+5 years, ~4.70) were remarkably similar. Those with elevated LVEDP tended to be slightly older (66?4 vs 59k4yrs, p=O.24). Passive diastolic LV compliance was significantly lower in those with elevated resting EDP (3.wO.4 vs 4.2+0.4mL/mmHg/m*, ~40.05). Active diastolic relaxation was also impaired, Tau (53.7 +I.0 vs 37.9&2.9msec, p=O.OOS) and dP/dt,,, (1528*140 vs -1840+96mmHglsec, p=O.O6). Load-independent indices of systolic function were the similar in the two groups. Whether these changes are a manifestation of the aging process or related to individual propensity to diastolic dysfunction in response to hypertension requires further investigation.
and Circulation
CARDIAC FUNCTION IN RATS WITH THYROID DYSFUNCTION USING HIGH FREQUENCY ECHOCARDIOGRAPHIC IMAGING. L Browo’l. IL ml. K WilsonZ.. J L Fawcett2 and D E&&Q&.
The cardiovascular effects of pneumoperitoneum (PP) include increases in systemic vascular resistance. arterial pressure and central venous pressure. Cardiac index is relatively unchanged in patients of ASA Class 1-2, but may be compromised in patients with cardiac disease. Laparoscopic surgery with PP is frequently undertaken in obese patients. The aim of the study was to determine the impact of obesity in combination with PP on left ventricular wall stress, a major determinant of myocardial oxygen demand. Methods: Transoesophageal echocardiography (TOE) was performed during laparoscopic surgery on 7 obese females with body mass index (WI) greater than 35 kg/m*. and 8 female controls of normal weight. Patients were ventilated to maintain normocapnia. Blood pressure was measured invasively. Lefl ventricular (LV) meridional end-systolic wall stress was calculated from blood pressure values and systolic LV dimensions obtained from transgastric short axis TOE images at the midpapillary level. The effect of 20 mmHg PP was assessed in the supine, Trendelenburg and reverse Trendelenberg positions. Data were compared using ANOVA and P < 0.05 was considered significant. Results: Obese patients were younger than controls (29.9t4.5 vs 42.3k7.3 yr), had higher weight (132.9+26.9 vs 61.6 ?13.2 kg) and BMI (47.9?6.7 vs 21.6i.3 kg/m’). Wall stress values and L=3 wallsees* systolic blood pressure are ,M - *‘mc BP 180 shown in the graph. Wall stress was higher in obese patients at baseline and with PP. Wall stress increased markedly with PP in obese, but not in control patients. Although there was no difference in systolic BP at baseline, it increased significantly with PP only in obese patients. Conc/usions: Obese patier may be at higher risk of myocardial ischaemia during laparoscopic abdominal surgery than patients of normal weight due to higher wall stress both before and during the period of pneumoperitoneum.
OF
Lung
ATRIAL “EJECTION FRACTION”: A NEW MEASURE OF ATRIAL FUNCTION. L .Thomas *I. D.Y .C. Leune’ and D.L. @. “Liverpool Hospital , Sydney, Australia and ‘Westmead Hospital, Sydney, Australia. Accurate estimation of atrial function has recently become clinically relevant. We sought to develop a novel echocardiographic measure of atrial function which would be more sensitive than existing parameters. Three groups of patients were studied: 1) Normal left ventricular (LV) function, 2) LV hypertrophy (LVH) and 3) LV dysfunction. All 44 patients were in sinus rhythm and had no significant valvular disease. Using 2D echocardiography we measured the following left atrial volumes from apical 2 and 4 chamber views by the modified biplane method of discs: maximum left atrial (LA) volume in ventricular systole (LAESV) and minimum LA volume in ventricular diastole (LAEDV). LA stroke volume (LASV) was calculated as LAESV- LAEDV and LAEF as ~ (LASVI LAEsV)X 100%. Peak mitral inflow A wave velocity, A wave velocity time integral (VT]) and atrial fraction ( [A wave VTI/ Total mitral inflow VTI] X 100%) were also measured using pulsed wave Doppler. Results: A significant difference was present between groups for LAEF (F=6.2, p=O.OOS) and post hoc tests confirmed this. No difference was noted between groups for peak mitral inflow A wave velocity, A wave VT1 or atrial fraction. 1 Normal LV ( LVH 1 LV dysfunct n I 30 Ill 13 Gil.4 47.6ti4.3 37k4.2 LAEF(%I A velocity (cm/s) 75.9SI.5 68.2i4.9 37.7i11.9 Atrial Fraction (%) 40.6i2.4 33.2i3.4 37.7il2 A wave VT1 (cm) 6.2kO.3 6.6iO.9 4.7ti.4 c
and LV dysfuncti& compared &h normh individuals. 2) fiEF appears to be the most sensitive indicator of atrial function in the three groups studied. 3) Commonly used parameters of mitral inflow A wave, A wave VT1 and atria1 fraction did not distinguish between groups. 4) Further studies with larger numbers of patients will be needed to further validate these findings.
48th Annual
Scientific
Meeting
Heart,
of CSANZ
INCREASED LEFT VENTRICULAR WALL STRESS WITH PNEUMOPERITONEUM IN OBESE FEMALES UNDERGOING LAPAROSCOPIC SURGERY D I Prior*. J SD una. J D Thomas. D G. l&h&& The Cleveland Clinic Foundation, ClevelaLd, OH, USA.
AAEMODYNAMIC EVIDENCE OF A DISPARITY DIASTOLIC DYSFUNCTION IN HYPERTENSION. &$Javward*. W.V. Kalnins., Department, St Vincent’s Hospital, Sydney, NSW.
2000; 9
1Department of Physiology and Pharmacology, The University of Queensland and the ZEchocardiographic Laboratory, The Prince Charles Hospital, Brisbane, Australia. Thyroid dysfunction often presents with marked cardiovascular symptoms tachycardia with high output failure in hyperthyroidism and bradycardia in hypothyroidism. This project assessed the changes in cardiac function noninvasively in chronically hyperthyroid or hypothyroid rats using high frequency, high frame rate echocardiographic imaging. Methods: 11 male Wistar rats (8 weeks old) were given triiodothyronine (T3; 0.05 m&g/day SC for 8 weeks) and measured after 0,4 and 8 weeks. To induce hypothyroidism, methimazole (500 mgfi drinking water) was given to 7 rats from day 18 of gestation until 6 months of age. Left parastemal and left apical echocardiographic images were obtained using the Hewlett Packard Sonos 5500 (12 Mhz frequency transducer) at an image depth of 3 cm using two focal zones. Left ventricular M-mode measurements at the level of fhe papillary muscles included left ventricular end-diastolic dimension (LVEDD), end-systolic dimension (LVESD), posterior wall in diastole (LVPWd) and fractional shortening (FS%). Pulsed-wave Doppler velocities were measured in the ascending and descending aorta and across the mitral valve; *p
IN THE DEGREE WOMEN WITH Cardiology
Women are more likely to develop left ventricular hypertrophy and diastolic heart failure in response to hypertension than men. Seventy percent of patients with hypertensive hypertrophic cardiomyopathy are women. We examined diastolic LV function using pressure-volume (PV) loops obtained by simultaneous micromanometer pressure and conductance catheter volume recordings in 8 postmenopausal hypertensive women with normal systolic function at routine coronary angiography. Passive diastolic function was defined by end-diastolic PV relations (EDPVR) during intermittent IVC occlusion, and active diastolic function by time constant of relaxation, Tau, and rate of pressure decline, dP/dt,,,,,. In 4 of the women, resting LVEDP was significantly greater compared to the remainder (17+1 vs 9flmmHg, pcO.01, meanBEM). These women were also character&d by smaller indexed LV volumes when compared to the 4 remaining hypertensive women (49f3 vs 59+3 mL/m’, p=O.O4). Despite these differences, systolic pressure (16ti6 vs 159fllmmHg) and duration of hypertension (14_+7 vs 11+5 years, ~4.70) were remarkably similar. Those with elevated LVEDP tended to be slightly older (66?4 vs 59k4yrs, p=O.24). Passive diastolic LV compliance was significantly lower in those with elevated resting EDP (3.wO.4 vs 4.2+0.4mL/mmHg/m*, ~40.05). Active diastolic relaxation was also impaired, Tau (53.7 +I.0 vs 37.9&2.9msec, p=O.OOS) and dP/dt,,, (1528*140 vs -1840+96mmHglsec, p=O.O6). Load-independent indices of systolic function were the similar in the two groups. Whether these changes are a manifestation of the aging process or related to individual propensity to diastolic dysfunction in response to hypertension requires further investigation.
and Circulation
CARDIAC FUNCTION IN RATS WITH THYROID DYSFUNCTION USING HIGH FREQUENCY ECHOCARDIOGRAPHIC IMAGING. L Browo’l. IL ml. K WilsonZ.. J L Fawcett2 and D E&&Q&.
The cardiovascular effects of pneumoperitoneum (PP) include increases in systemic vascular resistance. arterial pressure and central venous pressure. Cardiac index is relatively unchanged in patients of ASA Class 1-2, but may be compromised in patients with cardiac disease. Laparoscopic surgery with PP is frequently undertaken in obese patients. The aim of the study was to determine the impact of obesity in combination with PP on left ventricular wall stress, a major determinant of myocardial oxygen demand. Methods: Transoesophageal echocardiography (TOE) was performed during laparoscopic surgery on 7 obese females with body mass index (WI) greater than 35 kg/m*. and 8 female controls of normal weight. Patients were ventilated to maintain normocapnia. Blood pressure was measured invasively. Lefl ventricular (LV) meridional end-systolic wall stress was calculated from blood pressure values and systolic LV dimensions obtained from transgastric short axis TOE images at the midpapillary level. The effect of 20 mmHg PP was assessed in the supine, Trendelenburg and reverse Trendelenberg positions. Data were compared using ANOVA and P < 0.05 was considered significant. Results: Obese patients were younger than controls (29.9t4.5 vs 42.3k7.3 yr), had higher weight (132.9+26.9 vs 61.6 ?13.2 kg) and BMI (47.9?6.7 vs 21.6i.3 kg/m’). Wall stress values and L=3 wallsees* systolic blood pressure are ,M - *‘mc BP 180 shown in the graph. Wall stress was higher in obese patients at baseline and with PP. Wall stress increased markedly with PP in obese, but not in control patients. Although there was no difference in systolic BP at baseline, it increased significantly with PP only in obese patients. Conc/usions: Obese patier may be at higher risk of myocardial ischaemia during laparoscopic abdominal surgery than patients of normal weight due to higher wall stress both before and during the period of pneumoperitoneum.
OF
Lung
ATRIAL “EJECTION FRACTION”: A NEW MEASURE OF ATRIAL FUNCTION. L .Thomas *I. D.Y .C. Leune’ and D.L. @. “Liverpool Hospital , Sydney, Australia and ‘Westmead Hospital, Sydney, Australia. Accurate estimation of atrial function has recently become clinically relevant. We sought to develop a novel echocardiographic measure of atrial function which would be more sensitive than existing parameters. Three groups of patients were studied: 1) Normal left ventricular (LV) function, 2) LV hypertrophy (LVH) and 3) LV dysfunction. All 44 patients were in sinus rhythm and had no significant valvular disease. Using 2D echocardiography we measured the following left atrial volumes from apical 2 and 4 chamber views by the modified biplane method of discs: maximum left atrial (LA) volume in ventricular systole (LAESV) and minimum LA volume in ventricular diastole (LAEDV). LA stroke volume (LASV) was calculated as LAESV- LAEDV and LAEF as ~ (LASVI LAEsV)X 100%. Peak mitral inflow A wave velocity, A wave velocity time integral (VT]) and atrial fraction ( [A wave VTI/ Total mitral inflow VTI] X 100%) were also measured using pulsed wave Doppler. Results: A significant difference was present between groups for LAEF (F=6.2, p=O.OOS) and post hoc tests confirmed this. No difference was noted between groups for peak mitral inflow A wave velocity, A wave VT1 or atrial fraction. 1 Normal LV ( LVH 1 LV dysfunct n I 30 Ill 13 Gil.4 47.6ti4.3 37k4.2 LAEF(%I A velocity (cm/s) 75.9SI.5 68.2i4.9 37.7i11.9 Atrial Fraction (%) 40.6i2.4 33.2i3.4 37.7il2 A wave VT1 (cm) 6.2kO.3 6.6iO.9 4.7ti.4 c
and LV dysfuncti& compared &h normh individuals. 2) fiEF appears to be the most sensitive indicator of atrial function in the three groups studied. 3) Commonly used parameters of mitral inflow A wave, A wave VT1 and atria1 fraction did not distinguish between groups. 4) Further studies with larger numbers of patients will be needed to further validate these findings.