Fibrous Scars

Cirrhosis is the progressive replacement of normal hepatic cells by fibrous scar tissue. This scarring is accompanied by the loss of viable hepatocytes, which are the functional cells of the liver. Progressive cirrhosis is irreversible and leads to portal hypertension that is in turn responsible for many of the complications of advanced liver disease. These consequences include (but are not limited to) spontaneous bacterial peritonitis (SBP), hepatic encephalopathy, and variceal bleeding.1... 

Apoptosis of Other Cell Types in the Evolution of Fibrous Scar. 15... 

Positive reaction for caspase-9 has been also observed in cardiomyocytes bordering fibrous scar after MI, indicating that ongoing apoptosis might be important in ventricular remodeling after MI (Fig. 2B). 

Fig. 2. Fibrous scar after MI. (A) Hematoxylin and eosin. (B) Immunohistochemical staining for caspase-9 positive reaction in a cardiomyocyte bordering the scar.

In subacute MI, characterized histologically by the proliferation of granulation tissue and fibrous tissue, positive reaction for cleaved caspase-3 was observed in mononuclear inflammatory cells, myofibroblasts, and vascular endothelial cells (Fig. 5B). The number of positive cells decreased as granulation tissue was transforming into a fibrous scar [123]. 

Q1 An infarct is an area of dead tissue caused by interruption of blood flow. In a myocardial infarction (heart attack) caused by interruption of coronary blood flow, an area of cardiac muscle cells dies because of ischaemia. The patient may recover but the affected area of muscle may not survive it may be without blood flow for a prolonged period or the coronary blood vessel may be permanently blocked. The affected cardiac muscle is eventually replaced by fibrous scar tissue. 

Wound healing Repairs tissue defects Promotes fibrous scar Tissue... 

Fibrosis is often a normal response to tissue injury where the damaged cells of an organ are unable to regenerate. An example of this is seen in the heart following myocardial infarction, where the infiircted tissue is replaced by a strong fibrous scar. However there are many pathological conditions where the development of fibrosis is detrimental. The fibrotic tissue response of chronic inflammation is often associated with increased numbers of mast cells, and has been most extensively studied in pulmonary fibrosis and systemic sclerosis. 

Turpentine is also toxic to aquatic organisms and may cause long-term adverse effects in the aquatic environment. Coating action of resins can destroy water birds, plankton, algae, and fishes. Penaeid shrimp given abdominal injections were highly sensitive to turpentine. Turpentine-induced cellular inflammatory response was fibrous scar tissue in all tissues. Early gill and hepatopancreas tissue destruction, and extensive heart and abdominal tissue destruction was also observed. 

Scar tissue formation is directly responsible for the diflFiculty and morbidity associated with lead extraction (14-16). The difficulty in extraction is further enhanced by the use of passive fixation devices, longer implant durations, and the greater number of leads implanted in any given patient. The passive fixation devices promoted exuberant encapsulating fibrous scar formation at the myocardial electrode interface (Fig. 6.2). Scar tissue forms at the contact sites along vascular walls and, in the case of multiple electrodes, scarring can completely encompass multiple leads. In extreme cases, the scar tissue may completely obliterate the venous channel. One of the most common locations of scar formation is at the lead venous entry site. Leads implanted more than 8 years are the most difficult to remove. 

Fig. 6.2 Passive fixation lead tip completely encased in encapsulating fibrous scar. (From Belott PH. Endocardial lead extraction A videotape and manual. Armonk, NY Futura Publishing, 1998, with permission.)...

It is essential that a sheath pass over a lead down to the distal aspect of the electrode when removing a lead via the implant vein. The sheath disrupts the encapsulating fibrous scar at binding sites and nltimately allows for countertraction. Byrd developed telescoping stainless steel sheaths that are... 

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