The effects of intraventricular gradients on left ventricular ejection dynamics.

The generation of abnormal gradients between the apical cavity and the subaortic valvular region of the left ventricle in patients with hypertrophic cardiomyopathy (HCM) has traditionally been equated to a dynamic obstruction to left ventricular outflow. To examine this concept in more detail, left ventricular ejection dynamics were studied during cardiac catheterization in 30 patients with HCM and 29 patients with no evidence of cardiovascular disease. Using multisensor catheterization techniques, ascending aortic flow velocity and micromanometer left ventricular and aortic pressures were simultaneously recorded during rest (n = 47). Dynamic left ventricular emptying was also analyzed with frame-by-frame angiography (n = 46). The temporal distribution of left ventricular outflow was independently derived from both flow velocity and angiographic techniques. The HCM patients were subdivided into three groups: I, intraventricular gradients at rest (n = 9); II, intraventricular gradients only with provocation (n = 12); III, no intraventricular gradients despite provocation (n = 9). Expressed as a precentage of the available systolic ejection period (%SEP), the time required for ejection of the total stroke volume was (mean +/- 1 S.D.): Group I, 69 +/- 17% (flow), 64 +/- 6% (angio); Group II, 63 +/- 14% (flow), 65 +/- 6% (angio); Group III, 61 +/- 16% (flow), 62 +/- 4% (angio); control group, 90 +/- 5% (flow) 86 +/- 10% (angio). No significant difference was observed between any of the three HCM subgroups, but, compared with the control group, ejection was completed much earlier in systole independent of the presence or absence of intraventricular gradients. The presence of coexisting mitral regurgitation in 12 of the HCM patients did not alter these results. This study demonstrates that 'outflow obstruction', as traditionally defined by the presence of an abnormal intraventricular pressure gradient and systolic anterior motion of the mitral valve, does not impede left ventricular outflow in HCM. In a pure fluid dynamic sense, we believe that outflow obstruction does not exist in this disease entity.

Dynamics of left ventricular ejection in obstructive and nonobstructive hypertrophic cardiomyopathy.

The purpose of this study was to examine the dynamics of left ventricular ejection in patients with obstructive and nonobstructive hypertrophic cardiomyopathy (HCM). 30 patients with HCM and 29 patients with no evidence of cardiovascular disease were studied during cardiac catheterization. Using a single multisensor catheter, electromagnetically derived ascending aortic flow velocity and high fidelity left ventricular and aortic pressures were recorded during rest (n = 47) and provocative maneuvers (n = 23). Dynamic ventricular emptying during rest was also analyzed with frame-by-frame angiography (n = 46). Left ventricular outflow was independently derived from both flow velocity and angiographic techniques. The HCM patients were subdivided into three groups: (I) intraventricular gradients at rest (n = 9), (II) intraventricular gradients only with provocation (n = 12), and (III) no intraventricular gradients despite provocation (n = 9). During rest, the percentage of the total systolic ejection period during which forward aortic flow existed was as follows (mean +/- 1 SD): group I, 69 +/- 17% (flow), 64 +/- 6% (angio); group II, 63 +/- 14% (flow), 65 +/- 6% (angio); group III, 61 +/- 16% (flow), 62 +/- 4% (angio); control group, 90 +/- 5% (flow), 86 +/- 9% (angio). No significant difference was observed between any of the HCM subgroups, but compared with the control group, ejection was completed much earlier in systole independent of the presence or absence of intraventricular gradients. These results suggest that "outflow obstruction," as traditionally defined by the presence of an abnormal intraventricular pressure gradient and systolic anterior motion of the mitral valve, does not impede left ventricular outflow in HCM.

The relationship of central venous and pulmonary artery catheter position to acute right-sided endocarditis in severe thermal injury.

Autopsies of 1,105 burned patients completed from January 1951 through March 1977 were reviewed at the United States Army Institute of Surgical Research to investigate the relationship between central venous and pulmonary artery cannula use and the incidence of endocarditis. The incidence of endocarditis increased from 3.4 to 9.4% after 1969 when cardiac injury attributed to central venous cannula use was first noticed at autopsy. Since 1969, right heart nonbacterial and bacterial endocarditis has dramatically increased and the right heart has become the prevalent site of the cardiac lesions. Review of premortem chest roentgenograms from 14 recent autopsy cases with right heart endocardial injury confirmed that central venous catheter tips were placed in the vicinity of the right atrium or right ventricle in 86% of the cases. Pathogenetically, the majority of the infected right heart lesions are probably the result of cannula-induced injury, with subsequent thrombosis and later bacterial colonization during episodes of bacteremia which are common in burned patients.