Faculty Bibliography

BACKGROUND: The hydrodynamic cause of systolic anterior motion of the mitral valve (SAM) is unresolved. OBJECTIVES: This study hypothesized that echocardiographic vector flow mapping, a new echocardiographic technique, would provide insights into the cause of early SAM in obstructive hypertrophic cardiomyopathy (HCM). METHODS: We analyzed the spatial relationship of left ventricular (LV) flow and the mitral valve leaflets (MVL) on 3-chamber vector flow mapping frames, and performed mitral valve measurements on 2-dimensional frames in patients with obstructive and nonobstructive HCM and in normal patients. RESULTS: We compared 82 patients (22 obstructive HCM, 23 nonobstructive HCM, and 37 normal) by measuring 164 LV pre- and post-SAM velocity vector flow maps, 82 maximum isovolumic vortices, and 328 2-dimensional frames. We observed color flow and velocity vector flow posterior to the MVL impacting them in the early systolic frames of 95% of obstructive HCM, 22% of nonobstructive HCM, and 11% of normal patients (p < 0.001). In both pre- and post-SAM frames, we measured a high angle of attack >60 degrees of local vector flow onto the posterior surface of the leaflets whether the flow was ejection (59%) or the early systolic isovolumic vortex (41%). Ricochet of vector flow, rebounding off the leaflet into the cul-de-sac, was noted in 82% of the obstructed HCM, 9% of nonobstructive HCM, and none (0%) of the control patients (p < 0.001). Flow velocities in the LV outflow tract on the pre-SAM frame 1 and 2 mm from the tip of the anterior leaflet were low: 39 and 43 cm/s, respectively. CONCLUSIONS: Early systolic flow impacts the posterior surfaces of protruding MVL initiating SAM in obstructive HCM.

BACKGROUND: There are conflicting data on the incidence of ischemia by stress echocardiography in patients referred for dyspnea without accompanying chest pain. METHODS: A total of 311 consecutive patients with exertional dyspnea (without chest pain) referred to the echocardiography lab for ischemia evaluation from August 2008 to March 2012 were evaluated. Exercise by Bruce protocol or dobutamine stress echocardiography was performed. Resting left ventricular ejection fraction and segmental wall motion abnormalities were assessed. Multivariate logistic regression analysis was used to identify independent predictors of ischemia on stress echocardiography. RESULTS: The mean age was 61 years (range, 20-96 years), with 196 women (63%). Exercise stress was performed in 114 patients (37%); the rest of the patients underwent dobutamine stress. The patient population had a high burden of obesity, diastolic dysfunction, and pulmonary hypertension. Thirty patients (10%) had evidence of stress-induced ischemia (nine [8%] with exercise and 21 [11%] with dobutamine). In multivariate analysis, male gender (odds ratio, 2.8; P = .03), history of coronary artery disease (odds ratio, 3.5; P = .02), and resting wall motion abnormalities (odds ratio, 16.6; P < .01) were independent predictors of inducible ischemia. CONCLUSIONS: The incidence of stress-induced ischemia is low in patients referred for stress echocardiography with exertional dyspnea (without chest pain). Ischemia is more likely to be present in men with histories of coronary artery disease and resting wall motion abnormalities.

Subacute (medical) tamponade develops over a period of days or even weeks. Previous studies have shown that subacute tamponade is uncommonly associated with hypotension. On the contrary, many of those patients are indeed hypertensive at initial presentation. We sought to determine the prevalence and predictors of hypertensive cardiac tamponade and hemodynamic response to pericardial effusion drainage. We conducted a retrospective study of patients who underwent pericardial effusion drainage for subacute pericardial tamponade. Diagnosis of pericardial tamponade was established by the treating physician based on clinical data and supportive echocardiographic findings. Patients were defined as hypertensive if initial systolic blood pressure (BP) was >/=140 mm Hg. Thirty patients with subacute tamponade who underwent pericardial effusion drainage were included in the analysis. Eight patients (27%) were hypertensive with a mean systolic BP of 167 compared to 116 mm Hg in 22 nonhypertensive patients. Hypertensive patients with tamponade were more likely to have advanced renal disease (63% vs 14%, p <0.05) and pre-existing hypertension (88% vs 46, p <0.05) and less likely to have systemic malignancy (0 vs 41%, p <0.05). Systolic BP decreased significantly in patients with hypertensive tamponade after pericardial effusion drainage. Those results are consistent with previous studies with an estimated prevalence of hypertensive tamponade from 27% to 43%. In conclusion, a hypertensive response was observed in approximately 1/3 of patients with subacute pericardial tamponade. Relief of cardiac tamponade commonly resulted in a decrease in BP.

In this case, uncharacteristic clinical and laboratory findings led to an unanticipated diagnosis for a 24-year-old woman admitted for new-onset heart failure with features suggesting cardiac tamponade. Concomitant diagnosis of progressive mixed connective tissue disease associated with severe hypothyroidism was made. Despite early recognition (based on clinical and pathologic features) and rapid management (with glucocorticoids, thyroxine, metoprolol, lisinopril, furosemide, and milrinone), she deteriorated and died within 4 weeks.