Any time you lower blood pressure significantly, you should expect a reflex tachycardia, but most the time, the BP is lowered gradually and within acceptable parameters. The change in heart rate is therefore quite small. This effect can be blocked by meds that blunt the heart rate response, such as beta-blockers and certainly calcium blockers such as any form of diltiazem and verapamil. Both types of blockers will also lower the heart rate and blunt the reflex tachycardia that is commonly seen with direct vasodilators such as hydralazine and minoxidil. It’s important to be aware that there may be other causes of the increase in heart rate, such as anemia and volume depletion.