Angioplasty causes substantial injury to the coronary artery intima and media that is unrecognizable by angiography. On the basis of a substantial body of research in oncology and wound healing, it is hypothesized that restenosis is a manifestation of the general wound healing response expressed specifically in vascular tissue. The temporal response to injury occurs in three characteristic phases: inflammation, granulation and extracellular matrix remodeling. The specific expression of these phases in the coronary artery leads to intimal hyperplasia at 1 to 4 months. The major milestones in the temporal sequence of restenosis are platelet aggregation, inflammatory cell infiltration, release of growth factors, medial smooth muscle cell modulation and proliferation, proteoglycan deposition and extracellular matrix remodeling. Each step has potential inhibitors that could be used for preventive therapy. Resolution of restenosis, however, probably requires both creation of the largest possible residual lumen and substantial inhibition of intimal hyperplasia.

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A technique for the routine recording of His bundle (H) activity in man using a bipolar or multipolar catheter is described. The recording catheter is inserted percutaneously, via the Seldinger method, into the right femoral vein and advanced fluoroscopically into the right atrium. Placement of the pre-formed curve at the catheter tip across the tricuspid valve in nine patients resulted in stable recordings of His bundle activity in successive cardiac cycles. Right atrial pacing resulted in progressive lengthening of the P-H interval with increasing frequency but the H to S-wave interval remained constant at all rates. Similar lengthening of the P-H interval was produced during atrial pacing when pressure was applied to the carotid sinus. The use of this recording technique in man will facilitate diagnostic interpretation of the electrocardiogram and can be used in various investigations of atrioventricular and intraventricular conduction in man.

Sustained isometric handgrip exercise was studied in 28 patients, 19 with and nine without catheterization evidence of heart disease. Significant increases occurred in left ventricular systolic and left ventricular end-diastolic pressures (LVEDP), heart rate, cardiac output, and cardiac index, with decreases in stroke volume and stroke index. When control and abnormal groups were compared, no differences could be demonstrated in systolic pressure or heart rate increases. However, the LVEDP increase in the abnormal subjects (9.7 ± 1.7) was significantly ( P < 0.01) higher than in the controls (2.1 ± 0.7). In addition, cardiac index rose significantly ( P < 0.025) in the controls (0.8 ± 0.2), but not ( P < 0.1) in the abnormal subjects (0.2 ± 0.1). Conversely, there was a significant fall in stroke index in the abnormal ( P < 0.005) but not in the control ( P < 0.4) group. When work or stroke-work index-LVEDP relations were compared, the controls uniformly exhibited steep curves, whereas abnormal patients demonstrated curves that were either less steep or flat. ΔWork/ΔLVEDP ratio was [See Equation in PDF File]1.0 in the controls, with one exception, and [See Equation in PDF File]0.77 in the abnormal subjects, with one exception. The test was performed in less than 4 min and no adverse effects were observed. By virtue of its ease, simplicity, safety, and ability to distinguish normal and abnormal ventricular performance, sustained handgrip is a valuable new stress test.