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Computational methods for modeling of patient-specific mechanics of the heart and the circulatory system are developed. The 3-dimensionally resolved heart is coupled to a lumped-parameter 0-dimensional circulation model in a monolithic computational setting that allows for efficient simulations of cardiovascular conditions combined with gas transport, dissociation, as well as growth and remodeling phenomena. Efficient parameter estimation strategies are developed using multilevel and reduced-order modeling techniques, and the resulting overall model is applied to novel ventricular assist device development. Computergestützte Methoden zur Modellierung der patienten-spezifischen Mechanik des Herzens und des Kreislauf-Systems werden entwickelt. Das 3-dimensional aufgelöste Herz wird an ein 0-dimensionales Netzwerkmodell mit konzentrierten Elementen in einem monolithischen Ansatz gekoppelt, der die effiziente Simulation von Kreislaufzuständen erlaubt, kombiniert mit Gastransport und -dissoziation sowie Wachstums- und Remodellierungsprozessen. Effiziente Strategien zur Parameterschätzung mittels Mehrlevel- und Modellreduktionsansätzen werden entwickelt, und das Gesamtmodell findet Anwendung in der Entwicklung neuartiger Herzunterstützungssysteme.

The reservoir-wave hypothesis states that the blood pressure waveform can be usefully divided into a “reservoir pressure” related to the global compliance and resistance of the arterial system, and an “excess pressure” that depends on local conditions. The formulation of the reservoir-wave hypothesis applied to the area waveform is shown, and the analysis is applied to area and velocity data from high-resolution phase-contrast cardiovascular magnetic resonance (CMR) imaging. A validation study shows the success of the principle, with the method producing largely robust and physically reasonable parameters, and the linear relationship between flow and wave pressure seen in the traditional pressure formulation is retained. The method was successfully tested on a cohort of 20 subjects (age range: 20–74 years; 17 males). This paper: • Demonstrates the feasibility of deriving reservoir data non-invasively from CMR. • Includes a validation cohort (CMR data). • Suggests clinical applications of the method.

Detailed haemodynamic analysis may provide novel insights into the pulmonary circulation. Therefore, wave intensity and reservoir-excess pressure analyses were applied in the pulmonary artery to characterize changes in wave propagation and reservoir function during spontaneous respiration and dynamic stress tests. Right heart catheterization was performed using a pressure and Doppler flow sensor tipped guidewire to obtain simultaneous pressure and flow velocity measurements in the pulmonary artery in control subjects and patients with pulmonary arterial hypertension (PAH) at rest. In controls, recordings were also obtained during Valsalva manoeuvre and handgrip exercise. The asymptotic pressure at which the flow through the microcirculation ceases, the reservoir pressure related to arterial compliance and the excess pressure caused by arterial waves increased in PAH patients compared to controls. The systolic and diastolic rate constants also increased, while the diastolic time constant decreased. The forward compression wave energy decreased by ∼8% in controls and ∼6% in PAH patients during expiration compared to inspiration, while the wave speed remained unchanged throughout the respiratory cycle. Wave energy decreased during Valsalva manoeuvre (by ∼45%) and handgrip exercise (by ∼27%) with unaffected wave speed. Moreover, the reservoir and excess pressures decreased during Valsalva manoeuvre but remained unaltered during handgrip exercise. In conclusion, reservoir-excess pressure analysis applied to the pulmonary artery revealed distinctive differences between controls and PAH patients. Variations in the ventricular preload and afterload influence pulmonary arterial wave propagation as demonstrated by changes in wave energy during spontaneous respiration and dynamic stress tests.

Background Vertebrobasilar dolichoectasia (VBD) is a rare disease characterized by significant expansion, elongation, and tortuosity of the vertebrobasilar arteries. Hydrocephalus is a rare compilation of VBD. Case description In this study, we report a 68-year-old male presenting with headache, progressive decreased visual acuity, memory loss, imbalance while walking, and episodes of urinary incontinency. The patient was diagnosed with dolichoectasia of basilar artery causing compression of the third ventricular outflow and thus, presenting with hydrocephalus documented with brain computed tomography scan and brain magnetic resonance imaging. The patient underwent surgical operation and ventriculoperitoneal shunt placement. Conclusion In the case of hydrocephalus or normal pressure hydrocephalous, VBD should be considered as a differential diagnosis.

Models of haemodynamics play a central role in current research directed to understanding and addressing cardiovascular disease. Although conventional windkessel and wave models are very useful, they are incompatible due to conflicting assumptions and neither comprehensively explain the basis and interdependencies of pressure/flow waves, mean pressure and reservoir filling/discharge phenomena. The hybrid reservoir-wave model was proposed to address this gap, but is not widely accepted due to theoretical inconsistencies and negative results from validation studies. We recently described a unified model of haemodynamics based on the concept of ‘wave potential’, which identifies physically meaningful information from the absolute values of the forward/backward components of pressure and flow. Within this paradigm, hydraulic power may also be separated into forward/backward components, thus allowing study of time-dependent cardiac and vascular effects that influence hydraulic power output and efficiency. Based on in vivo and numerical experiments, it has been shown that 1) absolute values of the pressure/flow/power components represent wave potential, spatial gradients of which produce waves that transfer hydraulic energy, 2) mean pressure is generated by waves, 3) wave potential is a measure of local conduit arterial reservoir function and stored hydraulic energy, and 4) the diastolic pressure decay and associated ‘self-cancelling’ diastolic waves can be explained purely on the basis of wave reflection and distal leakage of wave potential. Wave potential provides a unified and analytically simple paradigm of arterial haemodynamics that extends and is fully compatible with conventional wave separation, while overcoming the difficulties encountered with the reservoir-wave paradigm.

Synthetic grafts are widely used in cardiac and vascular surgery since the mid-1970s. Despite their general good performance, inability of mimicking the elastomechanical characteristics of the native arterial tissue, and the consequent lack of adequate compliance, leads to a cascade of hemodynamic and biological alterations deeply affecting cardiovascular homeostasis. Those concerns have been reconsidered in more contemporaneous surgical and experimental reports which also triggered some research efforts in the tissue engineering field towards the realization of biomimetic arterial surrogates. The present review focuses on the significance of the “compliance mismatch” phenomenon occurring after aortic root or ascending aorta replacement with prosthetic grafts and discusses the clinical reflexes of this state of tissue incompatibility, as the loss of the native elastomechanical properties of the aorta can translate into detrimental effects on the normal efficiency of the aortic root complex with impact in the long-term results of patients undergoing aortic replacement.

The anatomical differences between the pulmonary and systemic arterial system are the main cause of the difference in distribution of compliance. In the pulmonary arterial system compliance is distributed over the entire arterial system, and stands at the basis of the constancy of the RC-time. This distribution depends on the number of peripheral vessels, which is ∼8–10 times more in the pulmonary system than the systemic tree. In the systemic arterial tree the compliance is mainly located in the aorta (80% of total compliance in thoracic-abdominal aorta). The constant RC-time in the pulmonary bed results in proportionality of systolic and diastolic pressure with mean pressure and, in turn, in the constant ratio of oscillatory and mean power.

Purpose: Application of a comprehensive, user-friendly, digital computer circulatory model to estimate hemodynamic and ventricular variables. Methods: The closed-loop lumped parameter circulatory model represents the circulation at the level of large vessels. A variable elastance model reproduces ventricular ejection. The circulatory model has been modified embedding an algorithm able to adjust the model parameters reproducing specific circulatory conditions. The algorithm reads input variables: heart rate, aortic pressure, cardiac output, and left atrial pressure. After a preliminary estimate of circulatory parameters and ventricular elastance, it adjusts the amount of circulating blood, the value of the systemic peripheral resistance, left ventricular elastance, and ventricular rest volume. Input variables and the corresponding calculated variables are recursively compared: the procedure is stopped if the difference between input and calculated variables is within the set tolerance, At the procedure end, the model produces an estimate of ventricular volumes and E(maxi) along with systemic and pulmonary pressures (output variables). The procedure has been tested using 4 sets of experimental data including left ventricular assist device assistance. Results: The algorithm allows the reproduction of the circulatory conditions defined by all input variable sets, giving as well an estimate of output variables. Conclusions: The algorithm permits application of the model in environments where the simplicity of use and velocity of execution are of primary importance. Due to its modular structure, the model can be modified adding new circulatory districts or changing the existing ones. The model could also be applied in educational applications. (Int J Artif Organs 2008; 31: 1043-54)

Graphical abstract, The reservoir-wave hypothesis states that the blood pressure waveform can be usefully divided into a “reservoir pressure” related to the global compliance and resistance of the arterial system, and an “excess pressure” that depends on local conditions. The formulation of the reservoir-wave hypothesis applied to the area waveform is shown, and the analysis is applied to area and velocity data from high-resolution phase-contrast cardiovascular magnetic resonance (CMR) imaging. A validation study shows the success of the principle, with the method producing largely robust and physically reasonable parameters, and the linear relationship between flow and wave pressure seen in the traditional pressure formulation is retained. The method was successfully tested on a cohort of 20 subjects (age range: 20–74 years; 17 males). This paper: • Demonstrates the feasibility of deriving reservoir data non-invasively from CMR. • Includes a validation cohort (CMR data). • Suggests clinical applications of the method.

A human circulatory system is composed of more than 50,000 miles of blood vessels. Such a huge network of vessels is responsible for the elevated pressure values within large arteries. As such, modeling of large blood arteries requires a full modeling of circulatory system. This in turn is computationally not affordable. Thus, a multiscale modeling of the arterial network is a necessity. The multiscale approach is achieved through, first, modeling the arterial regions of interest with 3D models and the rest of the circulatory network with reduced-dimensional (reduced-D) models, then coupling the multiscale domains together. Though reduced-D models can well reproduce physiology, calibrating them to fit 3D patient-specific Fluid Structure Interaction (FSI) geometries has received little attention. For this reason, this work develops calibration methods for reduced-D models using adjoint based methods. We also propose a reduced modeling complexity (RMC) approach that reduces the calibration cost of expensive FSI models using pure fluid modeling. Finally, all of the developed calibration techniques are tested on patient-specific arterial geometries, showing the power and stability of the proposed calibration methods.

The purpose of applying the reservoir-wave model to the pulmonary circulation is to validate the resulting reservoir and wave parameters against known physiologic responses. The reservoir model represents a modified windkessel and describes the lumped resistance to flow, compliance of vessels and the downstream pressure at which modeled outflow ceases. Applied to arteries and veins in tandem, a complete description of the pulmonary circulation is possible. The reservoir model determines the reservoir pressure, which is subtracted from measured pressure. The difference is called excess pressure and it is used with wave intensity analysis to quantify the effects of incident waves and their reflections. The changes to reservoir function and wave patterns may be helpful in providing extra diagnostic information regarding pulmonary hypertension and providing targets for treatment of this disease. Measurements of pressure and flow were made in the main pulmonary artery and pulmonary vein in 15 anesthetised, open-chest dogs. Six different conditions were created by the addition of blood volume and the application of positive end-expiratory pressure (PEEP). At each condition, hypoxic ventilation was used to create vasoconstriction and then, inhaled nitric oxide was used to create vasodilation. Ventilation changes are the focus of experimentation because hypoxia represents a pulmonary hypertension disease state and nitric oxide represents a common treatment. Both arterial and venous reservoir resistance increased with hypoxia and decreased with nitric oxide but only arterial reservoir resistance was fully reversed with nitric oxide. With excess pressure, arterial wave patterns revealed the presence of a prominent negative reflection occurring from the junction of arteries branching from the left or right pulmonary artery. Venous wave patterns showed that the left atrium and ventricle are responsible for the majority of measured pressure fluctuations but a wave transmitted from the pulmonary arteries is measurable during the filling of the left atrium. Overall, results are in general agreement with hypothesized physiological changes, which serves to validate the application of the reservoir-wave model and allows both the vascular characteristics and wave propagation to be quantified in ways that other models can not.

The mechanical load imposed by the systemic circulation to the left ventricle is an important determinant of normal and abnormal cardiovascular function. Left ventricular afterload is determined by complex time-varying phenomena, which affect pressure and flow patterns generated by the pumping ventricle. Left ventricular afterload is best described in terms of pressure-flow relations, allowing for quantification of various components of load using simplified biomechanical models of the circulation, with great potential for mechanistic understanding of the role of central hemodynamics in cardiovascular disease and the effects of therapeutic interventions. In the second part of this tutorial, we review analytic methods used to characterize left ventricular afterload, including analyses of central arterial pressure-flow relations and windkessel modeling (pressure-volume relations). Conceptual descriptions of various models and methods are emphasized over mathematical ones. Our review is aimed at helping researchers and clinicians obtain and interpret results from analyses of left ventricular afterload in clinical and epidemiological settings.

International audience; Blood flow in a steady magnetic field has been of great interest over the past years.Many researchers have examined the effects of magnetic fields on velocity profiles and arterial pressure, and major studies focused on steady or sinusoidal flows. In this paper we present a solution for pulsed magnetohydrodynamic blood flow with a somewhat realistic physiological pressure wave obtained using a windkessel lumped model. A pressure gradient is derived along a rigid vessel placed at the output of a compliant module which receives the ventricle outflow. Then, velocity profile and flow rate expressions are derived in the rigid vessel in the presence of a steady transverse magnetic field. As expected, results showed flow retardation and flattening. The adaptability of our solution approach allowed a comparison with previously addressed flow cases and calculations presented a good coherence with those well established solutions.

Purpose Application of a comprehensive, user-friendly, digital computer circulatory model to estimate hemodynamic and ventricular variables. Methods The closed-loop lumped parameter circulatory model represents the circulation at the level of large vessels. A variable elastance model reproduces ventricular ejection. The circulatory model has been modified embedding an algorithm able to adjust the model parameters reproducing specific circulatory conditions. The algorithm reads input variables: heart rate, aortic pressure, cardiac output, and left atrial pressure. After a preliminary estimate of circulatory parameters and ventricular elastance, it adjusts the amount of circulating blood, the value of the systemic peripheral resistance, left ventricular elastance, and ventricular rest volume. Input variables and the corresponding calculated variables are recursively compared: the procedure is stopped if the difference between input and calculated variables is within the set tolerance. At the procedure end, the model produces an estimate of ventricular volumes and Emaxl along with systemic and pulmonary pressures (output variables). The procedure has been tested using 4 sets of experimental data including left ventricular assist device assistance. Results The algorithm allows the reproduction of the circulatory conditions defined by all input variable sets, giving as well an estimate of output variables. Conclusions The algorithm permits application of the model in environments where the simplicity of use and velocity of execution are of primary importance. Due to its modular structure, the model can be modified adding new circulatory districts or changing the existing ones. The model could also be applied in educational applications.

During cardiac Magnetic Resonance Imaging the ElectroCardioGram recorded for synchronization is highly corrupted by various electromagnetic artifacts obstructing correct detection of the cardiac cycle. One of the contaminating sources is the MagnetoHydroDynamic effect that is due to the movement of the blood's charged particles in the magnetic environment. In this work, a reliable method for double synchronization on the cardiac and respiratory rhythm is developed which efficiently enhances the quality of high resolution cardiac MR images. The major alterations of human ECG signals are assessed using time and frequency domain analysis. Then, in order to predict this artifact's contamination levels, various flow models of blood in a magnetic field are studied. The effects of the magnetic field on the flow were shown, and induced surface voltages, liable to alter the ECG waveform, are estimated., Au cours des examens d'Imagerie par Résonance Magnétique du cœur, l'ÉlectroCardioGramme recueilli pour la synchronisation est fortement perturbé par plusieurs artéfacts gênant la bonne détection du cycle cardiaque. Une des sources contaminantes est l'artéfact MagnétoHydroDynamique, dû aux mouvements des particules chargées du sang dans le champ magnétique. Dans ce travail, une méthode fiable pour la double synchronisation sur le rythme cardiaque et respiratoire est élaborée, permettant l'amélioration des IRM cardiaques haute résolution. Les altérations temporelles et fréquentielles des signaux ECG provoquées par l'effet MHD sont examinées. Et, dans le but de prédire le niveau de contamination dû à cet artéfact, différents modèles d'écoulements sanguins dans un champ magnétique sont étudiés. Les effets du champ sur l'écoulement sont mis en évidence, et des potentiels surfaciques susceptibles de se superposer à l'ECG sont estimés.

Heute stehen dem Untersucher eine Reihe von radiologischen bildgebenden Modalitäten zur Verfügung, um den Schweregrad und die Relevanz von Stenosen peripherer Arterien einzuschätzen. Zu diesen bildgebenden Modalitäten zählen die Digitale Subtraktions-Angiographie (DSA), die Spiral-Computer-Tomographie (SCT), die Ultraschallverfahren und die Magnet-Resonanz-Tomographie (MRT). Mittels spektralem Dopplerverfahren, endovasaler Doppler-Sonde und der Magnet-Resonanz-Tomographie (MRT) sind darüberhinaus Aussagen über den Schweregrad einer Gefässverengung durch Erfassung der Hämodynamik (Messungen der Flussgeschwindigkeiten) möglich. Die Stenosen werden von den verschiedenen bildgebenden Modalitäten unterschiedlich dargestellt und häufig unterschiedlich quantifiziert. Es sollte die Möglichkeit geschaffen werden, exakt definierte Stenosen und verschiedene Stenosetypen reproduzierbar mit den unterschiedlichen bildgebenden Verfahren zu untersuchen. Ziel unserer Arbeit war die Entwicklung eines multimodalen Phantommodelles zur vergleichenden Untersuchung von simulierten Gefässstenosen unter Standardbedingungen und damit zur Objektivierung der Leistungsfähigkeit der unterschiedlichen Modalitäten bei Stenosedetektion und –quantifizierung. Mittels Membranpumpe und doppelseitigem Windkessel wurde ein pulsatiler Fluss erzeugt. Das Pumpenmodul mit der magnetfeldempfindlichen Elektronik wurde abgesetzt, um diese beim Einsatz im MRT ausserhalb der Gantry plazieren zu können. Dazu waren ausreichend lange Zuleitungen notwendig, die zur Erhaltung der Reproduzierbarkeit bei allen Modalitäten zum Einsatz kamen. Als Messstrecke kamen gut sonographierbare Schläuche aus Polyethylen zum Einsatz. Diese wurden mit jeweils drei kurzstreckig-konzentrischen, langstreckig-konzentrischen und plaqueartig-exzentrischen Stenosen unterschiedlicher Ausprägung versehen. Die reproduzierbare Herstellung der konzentrischen Stenosen erfolgte mittels Heissluft und Zug an den Enden der Polyethylenschläuche, die der plaqueartig-exzentrischen Stenosen mit definiertem Restlumen mittels Heissklebers und einem eingebrachten Metallstift. In Aufbau, Grösse und Beschaffenheit ermöglichten die Gefässphantome samt eingearbeiteten Stenosen eine realistische Simulation kleiner Gefässe. Als Referenzparameter kam bei unserem Versuchsaufbau ein identischer Schlauch ohne Stenosierung ( Nullstenose ) zum Einsatz, dieser machte Aussagen zu falsch-positiven Ergebnissen möglich. Das Polyethylen erwies sich als gut geeignetes Phantommaterial, da es stabil war, Stenosen darin relativ einfach reproduzierbar herzustellen waren, der akustische Impedanzsprung mit Wasser akzeptabel klein war und eine optische Kontrolle bei der reproduzierbaren Positionierung der intraluminalen Messkatheter und der externen Scanner möglich war. Eine Kennzeichnung der prä-, intra- und poststenotischen Messpunkte der Gefässphantome durch aussen sichtbare Farbringe erlaubte bei den Flussgeschwindigkeitsmessungen eine reproduzierbare Positionierung sowohl der intraluminalen Messkatheter als auch der externen Scanner. Als Füllungsmedium kam bei unserem Versuchsaufbau je nach bildgebender Modalität Wasser bzw. eine als Blutäquivalent dienende Latexpartikelsuspension (Cellcheck-400â) versetzt mit dem Echokontrastverstärker Levovistâ, dem nichtionischen Röntgenkontrastmittel Ultravist-370â oder dem MR-Kontrastmittel Magnevistâ zum Einsatz. Die Lösungen wurden mit einem Konservierungsmittel haltbar gemacht. Bei der von uns als Blutäquivalent eingesetzten Cellcheck-400-Lösung, handelt es sich um eine stabilisierte Suspension von Latexpartikeln, deren Größe und Konzentration im Bereich von mikrozytären Erythrozyten liegt. Sie erlaubte eine realistische Simulation des menschlichen Blutes. Die Suspension bot hinsichtlich Echogenität und konstanter Viskosität sehr gute Versuchsbedingungen. Die Partikel waren steril, stabil und leicht verfügbar. Die Reinigung der mit Cellcheck-400 verschmutzten Schläuche war unproblematisch. Thromben im System, wie sie bei Anwendung von Blut trotz Heparinisierung auftreten können, wurden vermieden. Das entwickelte Phantommodell war in allen radiologischen Modalitäten, trotz deren unterschiedlicher physikalisch-technischer Voraussetzungen, einsetzbar. Am Modell gelang sowohl die Erhebung der Bildgebung als auch die der Hämodynamik. Der Einsatz in der Ausbildung, insbesondere bei der vom Untersucher abhängigen Duplexsonographie ist empfehlenswert. Dabei hat der Anwender die Möglichkeit seine Einstellgewohnheiten am Phantom zu überprüfen, um Fehlerquellen zu erkennen und zu verringern. Die Entwicklung neuer Techniken ist patientenunabhängig möglich. Darüberhinaus können neu entwickelte Kontrastmittel und Signalverstärker ohne Patientenbeteiligung getestet werden.

The number of patients that are waiting for heart transplants far exceed the number of available donor hearts. Left Ventricular Assist Devices are mechanical alternatives that can help and are helping several patients. They work by taking blood from the left ventricle and ejecting that blood into the aorta. In the University of Louisville they are developing a similar device that will take the blood from the aorta instead of the ventricle. This new device is called an Artificial Vasculature Device. In this thesis the arterial system and AVD are modeled and a simple control algorithm for the AVD proposed. The arteries are modeled as a tube with linear resistance and inertia followed by a chamber with linear compliance and last a tube with linear resistance. The model is identical to the 4-element Windkessel model. The values for the resistances, inertia and compliance are identified using pressure and flow measurements from the ventricle and aortic root from a healthy patient. In addition to the Windkessel model the aortic valve is also modeled. The valve is modeled as a drum that closes the aorta and the parameters identified like before. The measurements are also used to model the left ventricle by assuming it has a constant compliance profile. The AVD is modeled using common modeling structures for servo motors and simple structures for tubes and pistons. The values for the AVD could not be measured and identified so they are fetched from preliminary motor and part specifications. The control algorithm for the AVD uses a wanted load to create a reference aortic flow. This wanted aortic flow is then achieved by using a PI controller. With these models and controller the interaction between the arterial system and AVD is investigated. With this preliminary understanding of the interaction further research can be made in the future to improve the understanding and improve the AVD itself.

It is generally accepted that the left ventricle (LV) hypertrophies (LVH) to normalize systolic wall stress (ςs) in chronic pressure overload. However, LV filling pressure (Pv) may be elevated as well, supporting the alternative hypothesis of end-diastolic wall stress (ςd) normalization in LVH. We used an LV time-varying elastance model coupled to an arterial four-element lumped-parameter model to study ventricular-arterial interaction in hypertension-induced LVH. We assessed model parameters for normotensive controls and applied arterial changes as observed in hypertensive patients with LVH (resistance +40%, compliance −25%) and assumed 1) no cardiac adaptation, 2) normalization of ςs by LVH, and 3) normalization of ςs by LVH and increase in Pv, such that ςd is normalized as well. In patients, systolic and diastolic blood pressures increase by ∼40%, cardiac output (CO) is constant, and wall thickness increases by 30–55%. In scenarios 1 and 2, blood pressure increased by only 10% while CO dropped by 20%. In scenario 2, LV wall thickness increased by only 10%. The predictions of scenario 3 were in qualitative and quantitative agreement with in vivo human data. LVH thus contributes to the elevated blood pressure in hypertension, and cardiac adaptations include an increase in Pv, normalization of ςs, and preservation of CO in the presence of an impaired diastolic function.

It is generally accepted that the left ventricle (LV) hypertrophies (LVH) to normalize systolic wall stress (σ(s)) in chronic pressure overload. However, LV filling pressure (P(v)) may be elevated as well, supporting the alternative hypothesis of end-diastolic wall stress (σ(d)) normalization in LVH. We used an LV time-varying elastance model coupled to an arterial four-element lumped-parameter model to study ventriculararterial interaction in hypertension-induced LVH. We assessed model parameters for normotensive controls and applied arterial changes as observed in hypertensive patients with LVH (resistance +40%, compliance -25%) and assumed 1) no cardiac adaptation, 2) normalization of σ(s) by LVH, and 3) normalization of σ(s) by LVH and increase in P(v), such that σ(d) is normalized as well. In patients, systolic and diastolic blood pressures increase by ~40%, cardiac output (CO) is constant, and wall thickness increases by 30-55%. In scenarios 1 and 2, blood pressure increased by only 10% while CO dropped by 20%. In scenario 2, LV wall thickness increased by only 10%. The predictions of scenario 3 were in qualitative and quantitative agreement with in vivo human data. LVH thus contributes to the elevated blood pressure in hypertension, and cardiac adaptations include an increase in P(v), normalization of σ(s), and preservation of CO in the presence of an impaired diastolic function.