# How Doctors Implant a Permanent Stent Using a Balloon > This patent describes the method for placing a permanent, expandable wire mesh tube inside a blood vessel or other body tube using a balloon-tipped catheter to widen it and keep it open. - **Patent:** US 4733665 - **Original title:** Expandable intraluminal graft, and method and apparatus for implanting an expandable intraluminal graft - **Owner:** Expandable Grafts Partnership - **Granted:** 1988 - **Status:** Public domain (expired) - **Times cited:** 2,425 - **Field:** medical_devices, cardiovascular, biotech ## What it does This patent describes a method for implanting a medical device, called a prosthesis or intraluminal graft, inside a body passageway like a blood vessel. First, the prosthesis is placed onto a catheter (Claim 1). The catheter and prosthesis are then inserted into the body passageway (Claim 1). Once at the desired location, a part of the catheter, specifically an inflatable balloon (Claim 3), is expanded. This expansion forces the prosthesis outward, permanently deforming it beyond its elastic limit (Claim 1) to contact the walls of the passageway. The prosthesis, often a wire mesh tube made of tantalum (Claims 4, 5), then remains in place to prevent the passageway from collapsing (Claim 7). After expansion, the balloon is deflated, and the catheter is removed (Claim 2). For example, this method can be used to open a narrowed artery and keep it wide. ## What it does NOT cover - Grafts that expand on their own without needing a balloon or other external force from the catheter. - Grafts that are not permanently deformed when expanded, meaning they would spring back to their original size. - Methods where the graft is expanded by a mechanism other than an inflatable portion of the catheter. - Grafts that are not delivered upon a catheter but are instead injected or deployed differently. - Grafts that are not tubular or made of intersecting elongate members, as described in Claim 13. ## The clever bit The key innovation was the idea of a graft that could be delivered in a collapsed state, then permanently expanded in situ by a balloon to a size determined by the body passageway, and critically, would stay expanded due to plastic deformation. This ensured the graft wouldn't migrate and would keep the vessel open. ## Real-world examples 1. Palmaz-Schatz stent 2. Balloon-expandable coronary stents 3. Balloon-expandable peripheral stents 4. Balloon-expandable vascular grafts ## Why it matters This patent is a cornerstone for modern interventional cardiology, specifically for balloon-expandable stents. It provided the fundamental method and device concept that allowed doctors to treat blocked arteries without major open surgery. The technology described here enabled the widespread adoption of coronary stenting, significantly improving outcomes for patients with heart disease. ## Frequently asked questions ### What does How Doctors Implant a Permanent Stent Using a Balloon cover? This patent describes the method for placing a permanent, expandable wire mesh tube inside a blood vessel or other body tube using a balloon-tipped catheter to widen it and keep it open. ### Who owns patent US 4733665? Expandable Grafts Partnership owns this patent, granted in 1988. ### When does this patent expire? This patent has expired and is now in the public domain — anyone can use the invention freely. ### What is patent US 4733665 cited by? This patent has been cited by 2425 later patents that build on its ideas. ### What problem does this patent solve? This patent is a cornerstone for modern interventional cardiology, specifically for balloon-expandable stents. It provided the fundamental method and device concept that allowed doctors to treat blocked arteries without major open surgery. The technology described here enabled the widespread adoption of coronary stenting, significantly improving outcomes for patients with heart disease. ### What does this patent NOT cover? Grafts that expand on their own without needing a balloon or other external force from the catheter. **Full plain-English explainer:** https://patentbrief.org/patent/us/4733665/palmaz-balloon-expandable-stent **Original patent:** https://patents.google.com/patent/US4733665 --- _Source: PatentBrief — https://patentbrief.org. Patent facts are from public records; the plain-English explanation is PatentBrief's._ ## Related patents Semantically similar inventions in the PatentBrief corpus: - [Catheter System for Opening and Closing Body Passages](https://patentbrief.org/patent/us/4195637/balloon-angioplasty-catheter-gruentzig) — This 1980 patent describes a medical catheter system with a guide catheter and a special dilatation catheter that can expand to open or close body passages, like blood vessels. - [The First Implantable Cardiac Pacemaker](https://patentbrief.org/patent/us/3057356/implantable-cardiac-pacemaker) — Wilson Greatbatch's 1960 patent for the first successful implantable heart pacemaker that used a battery to regulate heartbeat. - [How the First Automatic Implantable Defibrillator Works](https://patentbrief.org/patent/us/3614954/implantable-defibrillator-mirowski) — A 1970 invention by Medtronic that monitors heart rhythms and automatically delivers an electric shock to restart the heart if it detects a dangerous malfunction. - [Making Strong, Porous PTFE: The Gore-Tex Process](https://patentbrief.org/patent/us/3953566/gore-tex-expanded-ptfe) — This patent describes a specific process for rapidly stretching a highly crystalline form of PTFE plastic to create a strong, porous material with a unique internal structure, forming the basis for products like Gore-Tex. - [Leonarde Keeler's Early Mechanical Blood Pressure Recorder](https://patentbrief.org/patent/us/1788434/polygraph-lie-detector-keeler) — A 1925 invention by Leonarde Keeler designed to mechanically record a patient's arterial blood pressure over time.