Mean outflow resistance as a marker of left ventricular afterload

Timisjärvi, J.; Kettunen, Raimo; Rämö, P.

doi:10.1007/bf01906852

Cited by 5 publications

(6 citation statements)

References 17 publications

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“…This is quite in agreement with the observation of Timisj/irvi et al (12). All conditions which lead to an increase of the heart rate shift the linear relation between R and MOR of Equation (10) towards MOR, as can be seen in the Figure 2 of the cited paper.…”

Section: The Peripheral Resistance As Seen From the Left Ventriclesupporting

confidence: 90%

“…This comment on the paper by Timisj/irvi et al (12) shows that their main conclusions can be reached by a rather simple theoretical calculation. However, this does not diminish the value of these authors' experimental results since some details of the quotient AS/AT can only be determined experimentally.…”

Section: The Peripheral Resistance As Seen From the Left Ventriclementioning

confidence: 91%

“…Using these expressions we can describe the total peripheral resistance as the sum of two components: R = MOR + ADNs (9) MOR is defined as the mean outflow resistance and describes the impeding effect on the ventricular ejection of the arterial counterpressure during the systole (12).…”

Section: The Peripheral Resistance As Seen From the Left Ventriclementioning

confidence: 99%

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Some comments on ventricular afterload

Kenner

1987

Basic Res Cardiol

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In this issue of Basic Research in Cardiology a paper by Timisjärvi et al. is presented in which the problem of afterload, generated by the resistance against which the left ventricle is ejecting, is discussed. These authors have performed experiments in which they examine the role and validity of the so-called mean outflow resistance (MOR) of the left ventricle. In this editorial, the opportunity is taken to present some thoughts on the different possibilities of expressing the interrelation between the heart and the arterial system. It is intended to show how, from the first ideas about ventricular-arterial interaction bei Ph. Broemser (1935; 1) different concepts about simple descriptions of the functioning of the heart, the arterial system and the matching between both have evolved. In particular, the concept by Sunagawa et al. seems worthy of mention. An examination of this, and several other concepts, prove that the peripheral resistance and, particularly, the MOR, are important parameters that determine the influence of the arterial system on the performance of the heart. However, since MOR by definition is closely related to the total peripheral resistance, there is no essential need to introduce this resistance as a new concept of ventricular afterload. Calculations based on this definition of MOR demonstrate an agreement between theory and experimental results.

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Section: The Peripheral Resistance As Seen From the Left Ventriclesupporting

confidence: 90%

Section: The Peripheral Resistance As Seen From the Left Ventriclementioning

confidence: 91%

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Some comments on ventricular afterload

Kenner

1987

Basic Res Cardiol

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“…It has been suggested that in left heart assessment resistance to mean out¯ow is probably more suitable (TimisjaÈ rvi et al 1987). In our study both parametres behaved similarly in hypothermia, showing a marked increase in resistance.…”

Section: Discussionsupporting

confidence: 51%

Effects on dogs of surface-induced hypothermia and rewarming on the right heart function and pulmonary circulation

Palo

Lauri

Timisjärvi

2000

European Journal of Applied Physiology

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Hypothermia is commonly found in accidents on land and at sea, yet its pulmonary circulatory effects have not been studied before. To study the effects of hypothermia on the right heart function and pulmonary circulation, cardiac catheterization was carried out on nine anaesthetized beagle dogs. The dogs were cooled between ice bags until the temperature in the pulmonary artery was 25 degrees C and then rewarmed using a heating box especially constructed for this purpose. Heart rate decreased significantly (P < 0.01) during cooling. Cardiac output also diminished mainly because of decreased heart rate. Total pulmonary resistance increased in the cold (P < 0.05) and returned to the initial level during rewarming. The peak rate of increase in pressure (dP/dtmax) of the right ventricular pressure curve did not show any significant change. Retardation in relaxation in hypothermia was indicated by an increase (P < 0.01) in the peak negative dP/dt of the right ventricular pressure curve. According to our results, the contraction rate did not change, but the relaxation rate decreased significantly during cooling. No signs of heart failure were observed and all parameters returned to normal during rewarming. In conclusion, right ventricular function was not compromised even during deep hypothermia.

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“…The isometric contraction time (ICT) was taken to be the time interval between the onset of the left ventricular pressure rise and the time when the PEP ended. The electromechanical delay (EMD) was defined by a computerized method as the time between the onset of the Q-wave and the onset of the left ventricular systolic pressure rise (Timisjarvi et al 1987). The left ventricular pressure rise time was defined as the interval from the end of E M D to the peak in left ventricular pressure.…”

Section: Haemodynamic Testsmentioning

confidence: 99%

Left ventricular responses to experimental aortic coarctation in growing puppies

Leskinen

1991

Acta Physiologica Scandinavica

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The haemodynamic status of 8 coarctated and 7 sham-operated beagle puppies was studied by a catheterization technique at rest and during isoproterenol and volume loading at the ages of 7 (I) and 9 (II) months (5 and 7 months after the experimental coarctation). Proximal aortic systolic and pulse pressures were constantly higher in the coarctation group than in the control group (P less than 0.05), and the systolic pressure gradient across the coarctation was always significantly higher in the coarctation group [I at rest mean 45 +/- 5 (SD) vs 5 +/- 4 mmHg, P less than 0.001, and after I isoproterenol infusion 56 +/- 9 vs 10 +/- 6 mmHg, P less than 0.001, and after I dextran infusion 58 +/- 10 vs 8 +/- 7 mmHg, P less than 0.001]. The time constant of exponential isovolumic left ventricular pressure fall after the isoproterenol tests was longer in the coarctation group (I 28 +/- 8 ms and II, 30 +/- 4 ms) than in the control group (I, 21 +/- 2, P less than 0.05 and II, 19 +/- 3 ms, P less than 0.005), indicating impaired relaxation. The tension time index during the volume loading tests increased in the coarctation dogs (I, 4150 +/- 660 and II, 4080 +/- 810 mmHg s min-1) to higher levels than in the control group (I, 3550 +/- 220, II, 2540 +/- 1140 mmHg s min-1, P less than 0.05 both). Cardiac output, left ventricular end diastolic pressure, inotropic parameters and heart rate were similar in both groups during the infusions.(ABSTRACT TRUNCATED AT 250 WORDS)

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Mean outflow resistance as a marker of left ventricular afterload

Cited by 5 publications

References 17 publications

Some comments on ventricular afterload

Some comments on ventricular afterload

Effects on dogs of surface-induced hypothermia and rewarming on the right heart function and pulmonary circulation

Left ventricular responses to experimental aortic coarctation in growing puppies

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