Hello madam, your husband more likely is having intermittent arrhythmia. As you are telling, it is irregular, it may be an intermittent atrial fibrillation. But it can very well be a paroxysmal supra ventricular tachycardia too. What you have to do is to get an ecg at the time if that palpitations. Or else, you can get a holter monitoring done. In case if there is high blood pressure associated with sweating during this episode of palpitations, consider the remote possibility of pheochromocytoma, for which a urine test for metanephrine will help. Please make sure your husband is out of stress, as anxiety is the most common cause of palpitations.