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Mustafa Karamanoglu

Publications and source records attributed to Mustafa Karamanoglu.

6 recordsLinked to original sources
PubMed2006

A right ventricular pressure waveform based pulse contour cardiac output algorithm in canines.

Tracking changes in stroke volume or cardiac output (CO) can be useful in the diagnosis and treatment of various cardiac illnesses. Existing arterial pressure waveform based pulse contour CO algorithms perform poorly during altered systemic hemodynamics. In this study, a right ventricular pressure waveform based pulse contour CO algorithm was developed to estimate the amplitude and duration of a hypothetical triangular flow waveform in the pulmonary artery. This algorithm was tested against gold standard blood flow measurements in ten canines during acute perturbations to preload (inferior vena caval occlusion (IVCO), rapid saline infusion), afterload (descending aortic occlusion (DAO), serotonin, angiotensin II, sodium nitroprusside infusion), and cardiac contractility (dobutamine and propranolol infusion). The algorithm correctly predicted the changes in CO (r2 = 0.82) that varied from - 45 to 31% of the baseline levels. To explain this finding both the pulmonary arterial (PA) and the ascending aortic (AA) input impedances were modeled as three element windkessels. In the AA the peripheral resistance (from - 61 to 191%), characteristic impedance (from - 59 to 20%) and total arterial compliance (from - 49 to 34%) varied significantly with these perturbations. In contrast, these parameters in the PA changed little. In particular, except serotonin infusion, the characteristic impedance of the PA deviated only 6% (SD/mean) from baseline values. This suggests right ventricular pressure waveform based estimate of CO is possible during acute changes in left ventricular hemodynamics.

Algorithms↗
PubMed2004

Duration of diastole and its phases as a function of heart rate during supine bicycle exercise.

The duration of diastole can be defined in terms of mechanical events. Mechanical diastolic duration (MDD) is comprised by the phases of early rapid filling (E wave), diastasis, and late atrial filling (A wave). The effect of heart rate (HR) on diastolic duration is predictable from kinematic modeling and known cellular physiology. To determine the dependence of MDD of each phase and the velocity time integral (VTI) on HR, simultaneous transmitral Doppler flow velocities and ECG were recorded during supine bicycle exercise in healthy volunteers. Durations, peak values, and VTI using triangular approximation for E- and A-wave shape were measured. MDD, defined as the interval from the start of the E wave to end of the A wave, was fit as an algebraic function of HR by MDD=BMDD + MLMDD.HR + MIMDD/HR, derivable from first principles, where BMDD is a constant, and MLMDD and MIMDD are the constant coefficients of the linear and inverse HR dependent terms. Excellent correlation was observed (r2=0.98). E- and A-wave durations were found to be very nearly independent of HR: 100% increase in HR generated only an 18% decrease in E-wave duration and 16% decrease in A-wave duration. VTI was similarly very nearly independent of HR. Diastasis duration closely tracked MDD as a function of HR. We conclude that the elimination of diastasis and merging of E and A waves of nearly fixed durations primarily govern changes in MDD. These observations support the perspective that E- and A-wave durations are primarily governed by the rules of mechanical oscillation that are minimally HR dependent.

Adult↗
PubMed2004

Left ventricular chamber stiffness at rest as a determinant of exercise capacity in heart failure subjects with decreased ejection fraction.

Impaired exercise tolerance, determined by peak oxygen consumption (VO2 peak), is predictive of mortality and the necessity for cardiac transplantation in patients with chronic heart failure (HF). However, the role of left ventricular (LV) diastolic function at rest, reflected by chamber stiffness assessed echocardiographically, as a determinant of exercise tolerance is unknown. Increased LV chamber stiffness and limitation of VO2 peak are known correlates of HF. Yet, the relationship between chamber stiffness and VO2 peak in subjects with HF has not been fully determined. Forty-one patients with HF New York Heart Association [(NYHA) class 2.4 +/- 0.8, mean +/- SD] had echocardiographic studies and VO2 peak measurements. Transmitral Doppler E waves were analyzed using a previously validated method to determine k, the LV chamber stiffness parameter. Multiple linear regression analysis of VO(2 peak) variance indicated that LV chamber stiffness k (r2 = 0.55) and NYHA classification (r2 = 0.43) were its best independent predictors and when taken together account for 59% of the variability in VO2 peak. We conclude that diastolic function at rest, as manifested by chamber stiffness, is a major determinant of maximal exercise capacity in HF.

Blood Pressure↗
PubMed2004

Thermodynamic phase plane analysis of ventricular contraction and relaxation.

BACKGROUND: Ventricular function has conventionally been characterized using indexes of systolic (contractile) or diastolic (relaxation/stiffness) function. Systolic indexes include maximum elastance or equivalently the end-systolic pressure volume relation and left ventricular ejection fraction. Diastolic indexes include the time constant of isovolumic relaxation - and the end-diastolic pressure-volume relation. Conceptualization of ventricular contraction/relaxation coupling presents a challenge when mechanical events of the cardiac cycle are depicted in conventional pressure, P, or volume, V, terms. Additional conceptual difficulty arises when ventricular/vascular coupling is considered using P, V variables. METHODS: We introduce the concept of thermodynamic phase-plane, TPP, defined by the PdV and VdP axes. RESULTS: TPP allows all cardiac mechanical events and their coupling to the vasculature to be geometrically depicted and simultaneously analyzed. CONCLUSION: Conventional systolic and diastolic function indexes are easily recovered and novel indexes of contraction-relaxation coupling are discernible.

Adult↗
PubMed2004

The peak atrioventricular pressure gradient to transmitral flow relation: kinematic model prediction with in vivo validation.

Physiologists and cardiologists estimate peak transvalvular pressure gradients (DeltaP) by Doppler echocardiographic imaging of peak flow velocities using the simplified Bernoulli relationship: DeltaP (mm Hg) = 4V(2) (m/s). Because left ventricular filling is initiated by mechanical suction, V can be predicted by the motion of a simple harmonic oscillator by the parametrized diastolic filling formalism that characterizes E-wave contours by 3 unique simple harmonic oscillator parameters: initial displacement (x(o) cm); spring constant (k g/s(2)); and damping constant (c g/s). Parametrized diastolic filling predicts peak atrioventricular pressure gradient as kx(o), the peak simple harmonic oscillator force. For validation, simultaneous (micromanometric) left ventricular pressure and E-wave data from 19 patients were analyzed. Model-predicted peak gradient (kx(o)) was compared with actual gradient (DeltaP(cath)) and with 4V(2). Multiple linear regression results for all patients yielded highly significant relation between kx(o) and DeltaP(cath) (kx(o) = m(1)DeltaP(cath) + b(1), where m(1) = 40.7 +/- 8.0 dyne/mm Hg, b(1) = 1540 +/- 116 dyne, r(2) = 0.97, P <.001). Regression analysis showed no significant correlation between 4V(2) and DeltaP(cath) (4V(2) = m(2)DeltaP(cath) + b(2), where m(2) = 0.01 +/- 0.03, m(2)/s(2)/mm Hg and b(2) = 2.07 +/- 0.44 m(2)/s(2), P = nonsignificant). We conclude that E-wave analysis by parametrized diastolic filling predicts peak atrioventricular gradients reliably and more accurately than 4V(2).

Adult↗