CC Cardiol Croat Cardiologia Croatica Cardiol. Croat. 1848-543X 1848-5448 Croatian Cardiac Society CC_2013_8_9_307-308 10.15836/ccar.2013.307 Extended Abstract Inducible left-ventricular intracavity gradient during dobutamine stress echocardiography — a condition worth noting JakusNina1VelagicVedran2MemicDubravka2Separovic HanzevackiJadranka2MilicicDavor2CikesMaja2 University of Zagreb School of Medicine, Zagreb, Croatia University of Zagreb School of Medicine, University Hospital Center Zagreb, Zagreb, Croatia Correspondence to Nina Jakus, Medicinski fakultet Sveucilista u Zagrebu, Salata 3, Zagreb, Croatia; Phone: +385-91-560-5795; E-mail: nina.jakush@gmail.com 092013 092013 8 9 307 308 Croatian Cardiac Society 2013 Croatian Cardiac Society KEYWORDS: dobutamine stress echocardiographyintraventricular gradientdyspnoea

Objectives: To evaluate the incidence and left ventricular (LV) morphologic characteristics of patients developing dynamic intraventricular obstruction induced during dobutamine stress echocardiography (DSE).

Methods: We studied 77 patients (42 men - 55%; mean age 61±12 years) referred for standard high-dose DSE due to exertional dyspnoea or chest pain. The patients were divided into two groups — group I consisted of patients who developed a significant left-ventricular (LV) intracavitary gradient (>20 mmHg) during DSE (33 patients, 45% men, mean age 58.6 ± 12.5 years) and group II consisted of patients without an inducible gradient (44 patients - 61% men; mean age 62.5 ± 10.7 years). The intracavitary gradient was defined as a late-peaking left ventricular Doppler velocity profile exceeding basal velocity by 1 m/sec.

Results: 43% of the studied patients developed the gradient during high stages of dobutamine infusion (>20 mcg/kg/ min). Mean intracavitary gradient was 75.1 mmHg (range 20-135 mmHg). Patients in group I had statistically smaller LV cavity dimensions (Table 1) but their ejection fraction and fractional shortening were greater. These measurements were done using the Teicholtz method which is based on measuring the radial function of the LV (Table 1). Hypertension was present in a larger percentage of patients in the group I compared to the group II, however not reaching statistical significance (group I 30%, group II 18%, p = 0.28). According to patient histories somewhat more patients in the group I (27%) experienced symptoms like dyspnoea or chest pain during dobutamine infusion than in the group II (18%). The DSE study (Figure 1) was positive for inducible ischaemia in a significantly greater number of patients in the group II, compared to the patients developing the gradient (88% to 12%).

Echocardiographic data of the patients of group I (developed the gradient) and group II (did not develop the gradient).
Group I Group II p-value
IVSd (cm) 1.04±0.30 1.04±0.27 0.5
LVIDd (cm) 4.81±0.75 5.38±0.92 0.003
LVPWd (cm) 1.03±0.56 0.99±0.23 0.33
LVIDs (cm) 2.88±0.82 3.57±1.12 0.002
EDV (Teich) (mL) 111.97±39.56 144.30±61.94 0.01
ESV (Teich) (mL) 37.85±22.03 62.59±49.66 0.005
EF (%) 66.94±15.10 60.57±16.08 0.04
FS (%) 38.58±11.46 33.73±10.94 0.03

IVSd = interventricular septal thickness at diastole, LVIDd = left ventricle internal dimension in diastole, LVPWd = left ventricular posterior wall dimensions, LVIDs = left ventricular internal dimension in systole, EDV = end-diastolic volume, ESV = end-systolic volume, Teich = Teicholz, EF = ejection fraction, FS = fractional shortening, Ao Diam = aortic root diameter.

Continuous Doppler trace of the left ventricular outflow tract with an increasing dose of dobutamine. At maximum dose, the inducible gradient appears with the characteristic Doppler trace morphology.

Conclusion: An inducible LV intracavitary gradient occurred in a large number (43%) of patients referred to DSE in our centre. These patients had significantly smaller LV cavity dimensions which, together with notably increased radial function, likely contributes to the development of the gradient. Higher values of LV radial function measurements are common in hypertension. Indeed, we noted a higher incidence of hypertension in the group developing the intracavitary gradient. In this group of patients, the occurrence of inducible ischaemia was significantly lower. (1-3)

Literature PellikkaPAOhJKBaileyKRNicholsBAMonahanKHTajikAJ. Dynamic intraventricular obstruction during dobutamine stress echocardiography. A new observation. Circulation. 1992;86(5):1429–32. 10.1161/01.CIR.86.5.14291423956 BarlettaGDel BeneMRGalliniC The clinical impact of dynamic intraventricular obstruction during dobutamine stress echocardiography. Int J Cardiol. 1999;70(2):179–89. 10.1016/S0167-5273(99)00081-910454307 HeneinMYO’SullivanCSuttonGCGibsonDGCoatsAJ. Stress-induced left ventricular outflow tract obstruction: a potential cause of dyspnea in the elderly. J Am Coll Cardiol. 1997;30(5):1301–7. 10.1016/S0735-1097(97)00303-39350931