55 yr old male presents via ED with severe thoracic back pain which is tearing in nature. He is agitated and does not speak English. He has a raised BMI but unknown past medical history and unknown drug history. The clinical examination is unremarkable but he is found to be grossly hypertensive with a systolic of 195/100 mmHg with a heart rate of 80bpm. ECG is normal. His initial bloods are as follows:
Hb 150 g/L
WCC 7.2 x109/L
Plts 230 x109/L
Na 143 mmol/L
K 4.8 mmol/L
Ur 8.2 mmol/L
Cr 110 µmol/L
A CT thorax with contrast reveals an extensive Stanford Type B aortic dissection which extends from the arch of the aorta into both iliac vessels. There is significant flow within the false lumen and the left renal artery arises from the false lumen. Other major blood vessels arise from the true lumen. There is evidence of atherosclerotic disease and narrowing of both renal arteries.
The dissection is for conservative management with the primary goal to achieve rapid blood pressure control aiming for a systolic blood pressure of 120mmHg. Consequently, he is admitted to critical care for close monitoring.
What is the most appropriate first line pharmacological treatment for his hypertension?