Influence of the pericardium on left ventricular end-diastolic pressure-segment relations during early and later stages of experimental chronic volume overload in dogs.

Abstract

SUMMARY. Although the pericardium can exert a restraining effect on filling of the normal left ventricle, it is uncertain to what extent the pericardium influences left ventricular filling during chronic volume overload. We measured left and right ventricular pressure and left ventricular segment dimension before and after pericardiectomy over a range of left ventricular end-diastolic pressure from <5 to >20 mm Hg in open-chest dogs with volume overload due to a prior systemic arteriovenous fistula. In six dogs studied "early" (7-9 days) during volume overload, left ventricular end-diastolic dimension was significantly larger and right ventricular end-diastolic pressure lower following pericardiectomy at matched levels of left ventricular end-diastolic pressure greater than 10-12 mm Hg. In six dogs studied "late" (34-50 days) during chronic volume overload, there were no significant changes in left ventricular end-diastolic dimension after pericardiectomy at comparable levels of end-diastolic pressure. To account for the influence of changes in right ventricular enddiastolic pressure after pericardiectomy, we also compared left ventricular end-diastolic dimensions before and after pericardiectomy at matched "corrected" left ventricular end-diastolic pressure [(left ventricular end-diastolic pressure) -(right ventricular end-diastolic pressure X interventricular septal surface area/total left ventricular surface area)]. This "correction" of the left ventricular enddiastolic pressure did not significantly alter the results in either the "early" or "late" group. These results indicate that restraint to filling by the pericardium in this model of volume overload is present early but becomes markedly diminished during later phases. (Circ Res 50: 501-509, 1982)A NUMBER of prior studies have demonstrated that the pericardium may normally restrain left ventricular filling (Hefner et al., 1961;Bartle et al., 1968; Spotnitz and Kaiser, 1971;Glantz et al., 1978;Shirato et al., 1978;Mirsky and Rankin, 1979;Stokland et al., 1980). Although the absolute magnitude of this effect and the level of diastolic pressure and volume at which it begins are uncertain, it appears to be present consistently at left ventricular diastolic pressures above the normal operating range. Therefore, early during the course of volume overload lesions, before there has been a chance for either major left ventricular dilatation and hypertrophy, it is possible that the pericardium might have a physiologically significant restraining effect, providing the left ventricular diastolic pressure is abnormally elevated. Indeed, there is inferential evidence in patients (Bartle and Hermann, 1967) that this occurs. However, there is no information available as to whether the effect persists during later phases of chronic volume overload or whether, instead, the pericardium enlarges in parallel with an increase in cardiac mass, thus diminishing any restraining effect. In the present study, we sought to determine directly whether the pericardium limits left ven...

Dynamic ventricular interaction in the conscious dog.

“…Whereas it was not the intent of the current studies to determine the role of the percardium in ventricular interaction, the extent to which the pericardium absolutely affects this interaction in the normal heart may limit the general application of our results. The role of the pericardium in abnormal, chronically dilated hearts is even less well understood, although studies in a chronically volume overloaded canine model suggested that the pericardium dilated to accommodate the chronic cardiac dilation and markedly diminished the restrictive effects of the pericardium on ventricular filling (LeWinter and Pavelec, 1982). A more precise quantification of the role of the pericardium in ventricular interaction in the normal conscious dog model awaits development of techniques that do not abnormally alter its physiology-…”

Pericardial influences on ventricular filling in the conscious dog. An analysis based on pericardial pressure.

“…The expansion of ventricular dimensions, indicating augmentation of total intrapericardial volume, combined with the decline in transpericardial pressure, implied an increase in pericardial compliance. These data provide information regarding the time course of pericardial relaxation over the period intermediately between acute, open-chest studies (Glantz et al, 1978;Stokland et al, 1980) and the more recent work regarding pericardial creep in long-term studies of chronic volume overload (LeWinter et al, 1982). Thus, in addition to the length, placement, and precise closure of the pericardiotomy, pericardial retraction may account for the divergent results among various studies.…”

“…Data from the dogs studied sequentially suggested that substantial limitation of ventricular filling was present immediately after instrumentation but reversed with time. This early restraining effect may have been related to pericardial retraction occurring during instrumentation, and reversal of this effect may be analogous to pericardial creep (Rabkin et al, 1974;LeWinter et al, 1982). As illustrated by data from one of these dogs (Fig.…”

The pathophysiology of heart failure: a tale of two old paradigms revisited

“…The pericardium, however, can grow and therefore adapt to chronic increases in cardiac volume; 16 it therefore was assumed that although pericardial constraint and DVI might be important in acute situations, they were unlikely to be important in chronic HF. This was shown to not be the case.…”