Dean T. Mason

Hazards of angioscopic examination: Documentation of damage to the arterial intima

The fiberoptic scope is increasingly used in the coronary and peripheral arteries to quantitate the degree and type of arterial obstructive disease and to inspect the results of procedures such as bypass grafting and laser irradiation of obstructive lesions. Since little is known about this instruments potential complications, we passed a variety of fiberoptic scopes (1.8 to 3.6 mm outer diameter) in fresh postmortem pig coronary arteries and live monkey and canine peripheral arteries, and observed the intraluminal anatomy through the angioscope. No perforations were created, but ridges rising from the vascular luminal surface, avulsion of the endothelial lining, and small flaps attached at one end to the vessel wall were observed. Histologically, subintimal and medial tears were evident. Inserting large diameter scopes or making frequent passes (10 to 100) in coronary arteries increased intravascular injury. The use of small diameter flexible scopes or infrequent passes (less than 10) in the larger iliac and femoral arteries of live monkeys and dogs resulted in a lower frequency of myointimal sloughing or flap formation. Current fiberoptic scopes are not ideal angioscopes; they have a rigid tip, cannot be steered adequately, and are relatively stiff, resulting in a high probability of intraluminal injury, especially when used in small tortuous arteries. To decrease the risk of such injury, we recommend gentle manipulations while passing the scope and use of the smallest diameter scope possible. We further suggest limited use of the fiberscope, or at least limiting the number of passes in small vessels such as coronary arteries.

Arrhythmias in Patients with Mitral Valve Prolapse: Types, Evaluation, and Therapy

A wide spectrum of cardiac rhythm and conduction disorders occur in patients with all types of valvular heart disease. However, certain types of valvular disease have a special predilection for arrhythmias, including atrial and ventricular tachyarrhythmias as well as bradyarrhythmias, inherent to the etiology of the condition itself. Most notable in this regard is mitral valve prolapse, in which cardiac dysrhythmia is now recognized as the complication of highest frequency. The principal purpose of this article is the delineation of the characteristics and management of rhythm disorders in the mitral valve prolapse syndrome.

Laser recanalization in severe end-stage peripheral vascular disease

Abstract Application of lasers to vaporize coronary atherosclerotic obstruction was initially described in 1981. 1 Since then, the technique has been applied clinically to coronary arteries on an experimental basis. 2 This report objectively describes successful long-term laser recanalization using a catheter containing a laser-heated metal cap 3 in a patient with severe end-stage peripheral vascular disease.

Applicability of laser to assist coronary balloon angioplasty

Severe atherosclerotic obstructed coronary artery disease (CAD) may preclude passage of a balloon catheter for transluminal coronary angioplasty (TCA). Since lasers have been shown to effectively vaporize CAD plaque, the initial application of laser to effect a lumen large enough to accommodate the angioplasty catheter for further dilatation was explored. Eleven postmortem human CAD segments which did not permit passage of a 1.33 mm shaft diameter angioplasty catheter were studied. Argon laser radiation (14 to 90 J) transmitted via 400 micron core diameter quartz fiber onto the stenotic channel of 0.58 mm created a vaporized lumen of 1.77 mm (mean increase of 1.31 +/- 0.25 mm, p less than 0.001). The laser procedure allowed the balloon angioplasty catheter to be pushed into the stenosis. TCA was then performed (7 atm, 45 seconds) and expanded the channel to 2.12 mm (additional mean increase of 0.38 +/- 0.07 mm, p less than 0.001). In terms of percent luminal narrowing, laser radiation reduced obstruction from 80% to 45% (mean difference of -38.7 +/- 4.6%, p less than 0.001), and TCA caused a further decrease to 37% (mean difference of -9.3 +/- 1.9%, p less than 0.001). Thus, in tight atherosclerotic lesions, the laser may be useful in creating an initial opening enabling the placement of the balloon angioplasty catheter which, in turn, can further dilate the lased stenotic coronary lumen.

Intravascular steerable guidewire for fiberoptic laser-heated metal cautery cap in dissolution of human atherosclerotic coronary disease

moment of her hospitalization, there were no hematologic data clearly consistent with ALL, and the chest x-ray film did not reveal lymph nodal enlargement. Therefore echocardiography was initially useful for locating an abnormal mass, leading to a rapid, accurate diagnosis. In fact, in similar cases, the exact diagnosis was delayed with regard to the onset of pericardial disturbances6 The disappearance of the mass after appropriate therapy, documented by echocardiography, is an additional interesting feature. In summary, the characteristic aspects of our case are represented by: (1) the onset of a T-ALL with a cardiac tamponade without signs of the hematologic disease and (2) the possible contribution of ,echocardiography to the diagnosis and follow-up of cases such as ours.

Effects of digitalis glycosides on the systemic arterial and venous system: clinical importance in the pathophysiology of congestive heart failure

Although the digitalis glycosides have been employed widely in clinical medicine for two centuries as the principal drug in the treatment of congestive heart failure, their pharmacologic principles have become established on a firm scientific basis only within the past three decades. The observation that the digitalis-induced stimulation of the force of contraction of the normal human heart is not translated into an increase in cardiac output (7), suggests possible extracardiac vascular effects of the glycosides (5). Indeed, studies in experimental animals have shown that the glycosides exert direct systemic vasoconstriction (10) and this finding has been extended to the peripheral arterial tree of patients during cardiopulmonary bypass in the course of heart operations (1). The purpose of this report is to delineate the clinical alterations produced by digitalis on the resistance vessels (systemic arterioles) and the capacitance beds (systemic veins) of the peripheral circulation (8), and then clarify the significance of these changes relative to the pathophysiology and treatment of congestive heart failure (9).

Hemodynamic responses of the acutely stressed neonatal right ventricle: A maturational study in lambs☆

Right ventricular Starling responses to acute volume infusion in newborn lambs were compared to those in older groups of lambs. When peak stroke volume/kg was reached during infusion, right ventricular end-diastolic pressures for the newborn group were significantly lower (p less than 0.001) than those obtained for older groups, in spite of significantly higher resting and peak stroke volumes in the two younger groups. Newborn lambs developed tricuspid regurgitation and right-to-left foraminal shunting, demonstrated by echocardiography, at a mean end-diastolic pressure of 7.5 mm Hg. No right-to-left shunting was noted in older lambs. This study demonstrated a blunted Starling response in the newborn lambs right ventricle. The response to volume loading improved with maturation, but was still less than that reported for the left ventricle. Clinical implications regarding right ventricular immaturity and inadequate response to altered hemodynamic situations are raised.

Antihypertensive therapy and the concept of total cardiovascular protection

Drug-induced reduction of elevated blood pressure decreases cardiovascular mortality and morbidity in patients with moderate and severe hypertension. Furthermore, antihypertensive drug studies in mild hypertensive subjects (diastolic blood pressure 90 to 104 mm Hg) have shown protection against stroke, left ventricular hypertrophy, congestive heart failure and progression of renal damage, as well as improved patient longevity. The Hypertension Detection and Follow-up Program trial, recently carried out in the U.S., documented reduced coronary artery disease events (fatal and nonfatal) in special drug-treated patients with mild hypertension. From the standpoint of practical management and considering the ubiquity of essential hypertension, a modified stepped-care regimen advocating initial drug therapy with a beta blocker and addition of low-dose thiazide diuretic when necessary constitutes a judicious approach for widespread application. Although there are 8 orally active beta blockers currently approved in the U.S. for clinical use in systemic hypertension, only acebutolol possesses all of the salutary pharmacologic properties of cardioselectivity, intrinsic sympathomimetic activity and hydrophilicity, thereby making this compound an effective and safe beta-blocking agent for first-order management of a broad segment of the hypertensive population.

Argon laser radiation of human clots: differential photoabsorption in red cell rich and red cell poor clots

Since argon laser radiation (454-514 nm) can vaporize human clots, we determined whether the absorption of laser energies can differ among different types of blood clots. Thus we performed spectrophotometric studies and examined the ability of this laser to penetrate red cell rich and red cell poor clots. Fifty-four red cell rich and red cell poor clot samples, varying in depth from 1.8 to 5.0 mm, were subjected to 3, 5 and 7 watts from an argon laser beam. At a given power intensity, the deeper the red cell rich clot, the longer was the time needed to penetrate the clot. The higher the power used, the shorter was the red clot penetration time. In contrast, all power levels used up to 5 minutes did not penetrate any of the varying depths of red cell poor clots. Spectrophotometrically, the red cell rich clot had an absorption curve typical of hemoglobin pigment while the red cell poor clot, in the absence of hemoglobin, had poor absorption between 350 and 600 nm and was unable to absorb argon laser energies. Thus, the argon laser provides a therapeutic modality for human red cell rich clot dissolution but the present approach does not appear to be effective against red cell poor clots.

Application of Laser for Vaporization of Atherosclerotic Disease

Atherosclerotic disease accounts for significant morbidity, disability and mortality in man. As the disease progressively narrows the arterial lumen, blood flow is decreased to vital organs and structures such as the brain, heart, kidneys and leg muscles. The disease may also predispose afflicted vessels to thrombosis and embolism. Hence, cerebrovascular accidents, myocardial infarction, renal infarction, ischemia and gangrene of the lower extremities are all conditions that are frequently a consequence of atherosclerosis. Each year in the United States alone, an estimated 500,000 individuals are victims of stroke and 164,000 die; and approximately 1,500,000 develop myocardial infarction and 559,000 die1.