Effect of Intrathoracic Pressure on Left Ventricular Performance

Abstract

Left ventricular dysfunction is common in respiratory-distress syndrome, asthma and obstructive lung disease. To understand the contribution of intrathoracic pressure to this problem, we studied the effects of Valsalva and Müller maneuvers on left ventricular function in eight patients. Implantation of intramyocardial markers permitted beat-by-beat measurement of the velocity of fiber shortening (VCF) and left ventricular volume. During the Müller maneuver, VCF and ejection fraction decreased despite an increase in left ventricular volume and a decline in arterial pressure. In addition, when arterial pressure was corrected for changes in intrapleural pressure during either maneuver it correlated better with left ventricular end-systolic volumes than did uncorrected arterial pressures. These findings suggest that negative intrathoracic pressure affects left ventricular function by increasing left ventricular transmural pressures and thus afterload. We conclude that large intrathoracic-pressure changes, such as those that occur in acute pulmonary disease, can influence cardiac performance.

Sleep Apnea and Cardiovascular Disease

“…This negative intrathoracic pressure increases transmural gradients across the atria, ventricles, and aorta 118,119 and disrupts ventricular function 118 and autonomic and hemodynamic stability. 120 Consequences may include increased wall stress, increased afterload, increased atrial size, 121,122 impaired diastolic function, 121,123 thoracic aortic dilation, and propensity toward dissection.…”

Evaluation of Impact of Congestive Cardiac Failure on Selected Hematological Markers of Patients in Enugu, Nigeria

“…The apneic events lead to an increased negative intrathoracic pressure, from the normal level up to 80 mm Hg [9]. This leads to decreased preload, increased after load, and intraventricular septal shift to the left, with a cumulative effect of further decreasing cardiac output [10]. Hypoxia is another consequence of obstructive events, with a responsive pulmonary vasoconstriction that usually is not sustained during the day; however, repeated episodes can lead to right-ventricular hypertrophy [11].…”

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“…The effect of negative intrathoracic pressure in augmenting left ventricular afterload by virtue of a more negative transmyocardial pressure for a given pressure head was demonstrated by Buda et al via radiopaque intramyocardial markers during Muller and Valsalva maneuvers [21,25] In the setting of absent airflow and alveolar oxygenation, CNS mediated alpha adrenergic discharge occurs resulting in subsequent peripheral vasoconstriction and centrally shunted blood volumes [21,26]. The increased pulmonary blood volume results in transudation of fluid across the pulmonary membranes via leaky capillary membranes.…”