A 54-year-old patient was brought to a hospital with complaints of a sudden sharp pain in his chest that appeared when he was lifting a heavy object. The pain is localized in the center of his chest. It does not irradiate to other areas, nor does it intensify with changes in the position of the body. The pain was accompanied by nausea without vomiting. No respiratory symptoms are observed. The man has a history of essential hypertension and takes angiotensin-converting-enzyme inhibitors. Objectively, his skin is pale and moist. His pulse is 115/min., respiratory rate – 20/min. ECG shows sinus tachycardia. Chest Xray shows a darkening in the upper left and lower right segments. His cardiac enzyme levels are normal. Make the right diagnosis: