A catheter for injecting medicants into the endocardium, myocardium or other portions of the cardiovascular system is presented where the catheter has apertures therein for ejection and retraction of a needle. The catheter is designed for the apertures in the catheter to press against the tissue to be injected in the heart while the heart is beating. A needle for inserting a prescribed dose of a medicant is ejected through the aperture and a plunger, pump, or diaphragm is moved to deliver a dose of the medicant to tissue adjacent the aperture. By use of the catheter gene therapy, wherein a small does of a gene are injected into the endocardium of the right or left ventricle, can be used to grow new blood vessels in the injected area of a damaged heart. The apertures in the catheter can be spaced at a prescribed distance for the dosage of medicant to form a precise pattern of injections in the area to be treated. The catheters may be used for any treatments of a human or animal patient where injections are required in the heart, veins or arteries of the cardiovascular system.