Simultaneous conductance catheter and dimension assessment of left ventricle volume in the intact animal.

Applegate, Robert J.; Cheng, Che Ping; Little, William C.

doi:10.1161/01.cir.81.2.638

Cited by 120 publications

(43 citation statements)

References 45 publications

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“…54 There are limitations to the volume catheter method for volume assessment that should be considered. Although prior studies have shown good linear correla-tions between conductance catheter signals and other measures, [55][56][57] there are concerns about potential nonlinearity to the signal.56-" However, this limitation was unlikely to have significantly influenced the results.…”

Section: Study Limitationsmentioning

confidence: 95%

Diminished contractile response to increased heart rate in intact human left ventricular hypertrophy. Systolic versus diastolic determinants.

et al. 1993

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BACKGROUND Experimental studies indicate that in addition to diastolic dysfunction, hypertrophied myocardium can display depressed contractile responses, particularly at rapid heart rates, compounding reserve limitations. This study tests whether such abnormalities exist in intact human subjects at physiological paced rates and, if so, whether they are linked to simultaneous rate-dependent deterioration in diastolic function. METHODS AND RESULTS Ten subjects with left ventricular hypertrophy (LVH) and 8 normal control subjects were studied. Most LVH patients presented with dyspnea and/or pulmonary edema and had concentric hypertrophy. Since rapid pacing simultaneously alters cardiac filling volumes and pressures, pressure-volume relation analysis was used to better define changes in contractile response. Patients were instrumented with a conductance catheter and micromanometer for pressure-volume data recording and a balloon occluder at the right atrial-inferior vena caval junction to vary filling and thus generate function relations. Data were obtained at baseline and at three atrial pacing rates (100, 120, 150 min-1). In addition, single-beat force-interval data were used to indirectly examine calcium cycling kinetics. LVH subjects demonstrated baseline diastolic abnormalities, including prolonged relaxation, elevated end-diastolic pressure, and reduced chamber compliance. However, systolic function was similar to that in control subjects. With rapid pacing, normal subjects displayed a positive contractile response, whereas this was markedly diminished in LVH subjects. With abrupt termination of pacing and return to slower sinus rhythm, LVH subjects displayed greater initial potentiation followed by a more rapid decline than control subjects, suggesting abnormalities of calcium handling. Despite contractile abnormalities, diastolic function did not further deteriorate with rapid pacing and thus did not appear to be tightly linked to the systolic changes. CONCLUSIONS Pacing stress in intact human LVH can result in systolic impairment superimposed on preexisting but not worsened diastolic dysfunction. Abnormal calcium handling probably contributes prominently to this response.

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Section: Study Limitationsmentioning

confidence: 95%

Diminished contractile response to increased heart rate in intact human left ventricular hypertrophy. Systolic versus diastolic determinants.

et al. 1993

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“…LV contractility was quantified by the ESPVR, represented by the slope (Ees) of a straight line connecting the upper left-hand corners of the pressure-volume loops when loading conditions are changed by inflow occlusion (lo, 13,14) and by the volume intercept of the relation at a fixed pressure of 14 kPa (V14). We used this value to quantify its position along the volume axis as explained elsewhere ( 1 5).…”

Section: Materials a N D Methodsmentioning

confidence: 99%

Acceleration of Blood Flow Velocity in the Carotid Artery and Myocardial Contractility in the Newborn Lamb

et al. 1991

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ABSTRACT. We investigated the influence of quantitative changes in myocardial contractile state, reflected by changes in the end-systolic pressure-volume relationship (its slope and volume intercept) and by changes in the slope of the relationship between change in pressure per unit time and end-diastolic volume induced by P-adrenergic stimulation or inhibition, on the Doppler derived blood flow velocity wave form of the carotid artery, using a newborn lamb model. Acceleration time of the velocity wave form was investigated during control state I, during 4 and 8 pg/kg/min dobutamine infusion, during control state 11, and during 0.5 mg/kg propranolol infusion, respectively. Using multiple linear regression analysis with dummy variables, confounding effects such a s interanimal variability were removed. Acceleration time showed a strong relationship to both the slope and the volume intercept of the end-systolic pressure-volume relationship and to the change in pressure per unit time-end-diastolic volume relationship. The relations appeared to be independent of aortic pressure and relative resistance in the vascular bed of the carotid artery. These results indicate that acceleration of cerebral blood velocity may prove to be useful in assessing changes in myocardial contractile state of the newborn. ( critical with respect to treatment strategies. In human adults and animal models, peak linear acceleration (peak slope of upstroke in the velocity wave form), the mean acceleration slope (ratio between peak velocity minus diastolic velocity and acc-time), and acc-time (time from onset of ejection to peak velocity) of velocity wave forms of peripheral arteries have been related to qualitative changes in LV contractility (3)(4)(5)(6). No data are available yet for the relation between neonatal arterial blood flow velocity acceleration and a quantitative measure of myocardial contractility.We therefore designed a study to investigate the relationship between acceleration of the velocity wave form of a peripheral artery and quantified myocardial contractile state in the newborn lamb. Serial transfontanellar determination of the velocity wave form of cerebral arteries, e.g. the carotid arteries, is feasible, even in the most unstable preterm baby, with minimal handling and without disturbing the infant (7-8). For this reason, we used the velocity wave form of the lamb's carotid artery in our study. Myocardial contractility was expressed by the slope and volume intercept of the ESPVR (9) using the conductance catheter (10-12) and was changed by P-adrenergic stimulation (dobutamine) and by P-adrenergic inhibition (propranolol). The acc-time of the carotid artery velocity wave form was preferred because it relies on the time component only. contrary to peak linear acceleration and acceleration slope, which are dependent on the angle between Doppler beam and blood stream for reliable measurement. MATERIALS A N D METHODSilninlal preparation. Surgical and experimental procedures were reviewed and approved by the committee on ani...

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“…The validity of this technique for assessment of cardiac contractility has been established previously in adult animals 25 and has been adapted for analysis of newborn cardiac function by our group. 7 Recently, Applegate et al 26 have shown that the conductance catheter accurately measures absolute volumes at steady state but can underestimate the slope and position of the end-systolic PV relation when it is determined by caval occlusion. However, the end-systolic PV relation accurately measures the direction and magnitude of change in LV systolic function.…”

Section: = 16mmmentioning

confidence: 99%

Dose-related effects of magnesium on myocardial function in the neonate.

et al. 1994

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The antagonistic effects of magnesium ion as a calcium ion blocker may decrease calcium influx associated with ischemia. However, the effect of magnesium on the preischemic neonatal myocardium has not been investigated previously. The purpose of this study was to investigate the effects of the administration of increasing doses of magnesium on left ventricular performance in the neonate. We assessed left ventricular function (pressure-volume data obtained by the conductance catheter/micromanometer technique) in three groups (n=6 in each) of newborn pigs (3 to 5 days old) differing with respect to magnesium concentrations. Endsystolic elastance did not change during infusion in group A (magnesium=1.2 mmol/L), whereas in groups B (magnesium=8 mmol/L) and C (magnesium=16 mmol/L) it decreased significantly (P<.05) to 67±6% and 44±8% of baseline, respectively. The decrease in end-systolic elastance was associated with a significant reduction in cardiac output (P<.05) and stroke work (P<.05) in group C. After administration of magnesium, end-systolic elastance returned to baseline in group B in contrast to group C (78±3% of baseline value, P<.05). The slope constant of the end-diastolic pressure-volume relation decreased significantly (P<.05) from the preinfusion baseline values of 0.42±0.08 mL" 1 in group B and 0.46±0.05 mL" 1 in group C to 0.3±0.04 and 0.26±0.03 mL"', respectively, versus no change in group A. At the end of the experiment, the slope constant returned to baseline value in group B, whereas in group C it remained significantly lower (P<.05, 78±3% of baseline). We conclude that administration of 8 to 16 mmol/L magnesium affects the systolic function and alters the diastolic properties of the neonatal heart in a dose-response manner. can affect cardiac contractility and tension development by changing sarcolemmal and membrane binding of Ca 2 + , thus directly affecting resting membrane potentials and excitation-contraction coupling events.2 It is also now clear that small changes in free external Mg 2 + can exert significant effects on cardiac cell mechanical and electrical activities.3 Evidently, Mg 2 + can be considered as a natural Ca 2+ antagonist that may influence and control many cardiovascular functions.The effects of Mg 2 + on cardiovascular hemodynamics were studied mainly in adults.4 -5 However, the effects of Mg 2 + on cardiac mechanics in the intact neonatal or adult heart, using the pressure-volume (PV) relation, have not been studied. Therefore, this study was designed to examine the effects of the administration of varying doses of magnesium sulfate (MgSO 4 ) on left ventricular (LV) systolic and diastolic function in the neonate.

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Simultaneous conductance catheter and dimension assessment of left ventricle volume in the intact animal.

Cited by 120 publications

References 45 publications

Diminished contractile response to increased heart rate in intact human left ventricular hypertrophy. Systolic versus diastolic determinants.

Diminished contractile response to increased heart rate in intact human left ventricular hypertrophy. Systolic versus diastolic determinants.

Acceleration of Blood Flow Velocity in the Carotid Artery and Myocardial Contractility in the Newborn Lamb

Dose-related effects of magnesium on myocardial function in the neonate.

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