Chest pain, dyspnea and cardiac dysrhythmia are not uncommon symptoms in patients with pulmonary hypertension (PH). Subtle involvement of the left ventricle (LV) has been incriminated and several echocardiography reports addressed the issue of LV diastolic functional impairment in PH due to flattening of the septum, decreased diastolic and systolic volumes, with normal systolic function. Chest pain has been variably explained as right ventricular (RV) angina or pulmonary artery (PA) distension but no reports in the literature have so far investigated the question of the possibility of real LV myocardial ischemia.The present work addressed the above issue, using the technique of pulsed tissue-Doppler imaging (TDI) and 99m Tc Sestamibi Gated-SPECT. We studied 15 (non-belharzial ) patients (pts) with PH (7 males & 8 females; mean age: 39 ± 11.4, range 21-57 years), all pts presented with shortness of breath 8 with exertional chest pain. Following full clinical evaluation, all pts were subjected to 12-lead ECG, conventional M-mode, 2D-echocardiography & pulsed tissue-Doppler imaging (TDI), followed by rest Gated-SPECT nuclear imaging using a multi-SPECT scintillation gamma camera in the conventional 3-views and performing LV semi-quantitative analysis for ischemia scoring.Echo-parameters assessed included LVEDd, RVEDd, LV-%EF, PA-diameter and estimation of the systolic pulmonary artery pressure (SPAP). The pulsed tissue-Doppler imaging parameters included systolic myocardial velocity (Sm), early diastolic myocardial velocity (Em), the late diastolic myocardial velocity (Am) and the isovolumetric relaxation time (IRT). The Gated-SPECT parameters included evaluation of LV segmental hypoperfusion and total percentage of myocardial ischemia.Out of the fifteen patients studied, 12 (80%) exhibited SECT evidence of LV myocardial hypoperfusion (mean: 5%, range: 1%-10%) affecting only the basal to mid-segments of the interventricular septum ± LV inferior wall. The severity of the LV myocardial ischemia obtained by Gated-SPECT, correlated positively mainly with PA-diameter (r = 0.83), and less with RVEDd (r = 0.67) and SPAP (r = 0.62). Patients exhibiting LV myocardial ischemia showed T-wave inversion in the surface ECG leads (r = 0.81).The pulsed tissue-Doppler imaging of the LV ischemic segments showed impaired diastolic with preserved systolic functions compaired to the contralateral segments; Em-wave showed significant reduction of both basal anteroseptal and basal inferior segments in comparison to the postrolateral and antrolateral segments respectively (10.9 ±5.1 versus 19.1±4.1 cm/sec, p <0.03), and (7.3±5.2 versus 23.1±5.5 cm/sec, p <0.005).The isovolumetric relaxation time also showed significant prolongation in both basal antroseptal and basal inferior segments in comparison to the postrolateral and antrolateral segments respectively (121±23.1 versus 82.1±12.3 msec, p <0.005), and (153±22.3 versus 92.9±17.5 msec, p <0.01)In conclusion: Using Gated-SPECT & TDI techniques in this study, unmasked for the first time not only the real presence of LV myocardial ischemia, but also provided a pathophysiologic explanation for the impaired LV diastolic function in pulmonary hypertension.