James S. Forrester

Catheterization of the Heart in Man with Use of a Flow-Directed Balloon-Tipped Catheter

Abstract Pressures in the right side of the heart and pulmonary capillary wedge can be obtained by cardiac catheterization without the aid of fluoroscopy. A No. 5 Fr double-lumen catheter with a balloon just proximal to the tip is inserted into the right atrium under pressure monitoring. The balloon is then inflated with 0.8 ml of air. The balloon is carried by blood flow through the right side of the heart into the smaller radicles of the pulmonary artery. In this position when the balloon is inflated wedge pressure is obtained. The average time for passage of the catheter from the right atrium to the pulmonary artery was 35 seconds in the first 100 passages. The frequency of premature beats was minimal, and no other arrhythmias occurred.

American College of Cardiology/American Heart Association expert consensus document on electron-beam computed tomography for the diagnosis and prognosis of coronary artery disease

Coronary artery calcification is part of the development of atherosclerosis; it occurs exclusively in atherosclerotic arteries and is absent in the normal vessel wall. Electron-beam computed tomography (EBCT), the focus of this document, is a highly sensitive technique for detecting coronary artery calcium and is being used with increasing frequency for the screening of asymptomatic people to assess those at high risk for developing coronary heart disease (CHD) and cardiac events, as well as for the diagnosis of obstructive coronary artery disease (CAD) in symptomatic patients. The use of EBCT has the greatest potential for further determination of risk, particularly in elderly asymptomatic patients and others at intermediate risk. The calcium score has been advocated by some as a potential surrogate for age in risk-assessment models. EBCT has also been proposed as a useful technique for assessing the progression or regression of coronary artery stenosis in response to treatment of risk factors such as hypercholesterolemia. EBCT uses an electron beam in stationary tungsten targets, which permits very rapid scanning times. Serial transaxial images are obtained in 100 ms with a thickness of 3 to 6 mm for purposes of detecting coronary artery calcium. Thirty to 40 adjacent axial scans are obtained during 1 to 2 breath-holding sequences. Current EBCT software permits quantification of calcium area and density. Histological studies support the association of tissue densities of 130 Hounsfield units (HU) with calcified plaque. However, a plaque vulnerable to fissure or erosion can be present in the absence of calcium. Also, sex differences play a role in the development of coronary calcium, the prevalence of calcium in women being half that of men until age 60 years. EBCT calcium scores have correlated with pathological examination of the atherosclerotic plaque. This American College of Cardiology (ACC)/American Heart Association (AHA) Writing Group reviewed …

A new technique for measurement of cardiac output by thermodilution in man

Abstract A technique for measurement of cardiac output by thermodilution (COTD) in man has been described. Comparison with cardiac outputs determined simultaneously by the dye-dilution technique (CODYE) in 63 measurements in 20 patients showed close agreement of the 2 methods in a range of values from 2.9 to 8.0 liters/min (COTD = 0.96 CODYE + 0.2, r = 0.96). The reproducibility of measurements was 4.1 percent with the thermodilution and 5.4 percent with the dye-dilution technique. The thermodilution technique does not require withdrawal of blood during measurements and removal of blood for calibration. The calibration is simple and accurate. There is virtually no recirculation, so that a simple integrator can be used for determination of the area beneath the thermodilution curve.

A PARADIGM FOR RESTENOSIS BASED ON CELL BIOLOGY : CLUES FOR THE DEVELOPMENT OF NEW PREVENTIVE THERAPIES

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.

Use of Sildenafil (Viagra) in Patients With Cardiovascular Disease

The pharmaceutical preparation sildenafil citrate (Viagra) is being widely prescribed as a treatment for male erectile dysfunction, a common problem that in the United States affects between 10 and 30 million men. The introduction of sildenafil has been a valuable contribution to the treatment of erectile dysfunction, which is a relatively common occurrence in patients with cardiovascular disease. This article is written to appropriately caution and not to unduly alarm physicians in their use of sildenafil in patients with heart disease. Reported cardiovascular side effects in the normal healthy population are typically minor and associated with vasodilatation (ie, headache, flushing, and small decreases in systolic and diastolic blood pressures). However, although their incidence is small, serious cardiovascular events, including significant hypotension, can occur in certain populations at risk. Most at risk are individuals who are concurrently taking organic nitrates. Organic nitrate preparations are commonly prescribed to manage the symptoms of angina pectoris. The coadministration of nitrates and Viagra significantly increases the risk of potentially life-threatening hypotension. Therefore, Viagra should not be prescribed to patients receiving any form of nitrate therapy. Although definitive evidence is currently lacking, it is possible that a precipitous reduction in blood pressure with nitrate use may occur over the initial 24 hours after a dose of Viagra. Thus, for patients who experience an acute cardiac ischemic event and who have taken Viagra within the past 24 hours, administration of nitrates should be avoided. In the event that nitrates are given, especially within this critical time interval, it is essential to have the capability to support the patient with fluid resuscitation and α-adrenergic agonists if needed. In patients with recurring angina after Viagra use, other nonnitrate antianginal agents, such as β-blockers, should be considered. Other patients in whom the use of Viagra is potentially hazardous include those …

Thermodilution cardiac output determination with a single flow-directed catheter.

Abstract A single right heart catheter which allows simultaneous determinations of cardiac output, pulmonary artery pressure, pulmonary capillary wedge pressure, and right atrial pressure in critically ill patients is described. The catheter, which utilizes the thermodilution technique of cardiac output determination, may be rapidly and safely passed at the bedside without fluoroscopy.

Extent and severity of myocardial hypoperfusion as predictors of prognosis in patients with suspected coronary artery disease

The ability of exercise-induced myocardial hypoperfusion on thallium scintigraphy to predict coronary events was assessed in 1,689 patients with symptoms suggestive of coronary artery disease but without prior myocardial infarction or coronary artery bypass surgery. A total of 74 patients had a coronary event in the year after testing (12 cardiac deaths, 20 nonfatal infarctions and 42 referrals for bypass surgery more than 60 days after testing). Stepwise logistic regression identified only three independent predictors: the number of myocardial regions with reversible hypoperfusion (an index of the extent of hypoperfusion), the maximal magnitude of hypoperfusion (an index of the severity of hypoperfusion) and the achieved heart rate (an index of exercise performance). Both extent and severity were exponentially correlated with event rate (r greater than 0.97 and p less than 0.01 for each), whereas achieved heart rate was linearly correlated with event rate (r = 0.79 and p less than 0.05). On the basis of these data, a prognostic model was defined that employs extent and severity as stress-dependent orthogonal variables. Using this model, the predicted coronary event rate ranged over two orders of magnitude--from a low of 0.4% in patients able to exercise adequately without developing severe and extensive hypoperfusion at a low heart rate (less than 85% of their maximal predicted heart rate). Extent and severity of myocardial hypoperfusion, therefore, are important independent variables of prognosis in patients with suspected coronary artery disease.

Renal and Extrarenal Hemodynamic Effects of Furosemide in Congestive Heart Failure after Acute Myocardial Infarction

Abstract Furosemide, 0.5 to 1.0 mg per kilogram intravenously, was given to 20 patients with left ventricular failure after acute myocardial infarction. Within five to 15 minutes, average left ventricular filling pressure fell from 20.4 to 14.8 mm Hg, accompanied by a 52 per cent increase in mean calf venous capacitance. During the same period there was no physiologically important change in either urine output or heart rate, blood pressure and cardiac output. Peak increase in urine flow (from mean of 0.82 to 4.0 ml per minute) occurred at 30 minutes, and peak natriuretic effect at 60 minutes. Thus, the action of furosemide in the treatment of pulmonary congestion is immediate and is not related to its diuretic properties. Rather, the prompt fall in left ventricular filling pressure probably is primarily vascular in origin, since marked changes in venous capacitance accompany this phenomenon, which is only later supplemented by the increase in urine output and electrolyte excretion. (N Engl J Med 288:1087...

Detection and localization of tumor necrosis factor in human atheroma

Tumor necrosis factor (TNF) is a secretory product of normal macrophages that can cause cell necrosis, new blood vessel formation and thrombosis. These are also 3 characteristic features of the progression of stable atheroma to endothelial disruption. Accordingly, an immunohistochemical method was developed to detect TNF in human tissue. Using this method TNF positivity was demonstrated in 57 of 65 (88%) of tissue sections classified as atherosclerotic and in 5 of 11 (45%) sections classified as minimally atherosclerotic. TNF was absent in 6 sections classified as normal. TNF positivity was found not only in the cytoplasm of macrophages, but also in the cytoplasm and attached to the cell membrane of smooth muscle cells and endothelial cells of the human atheroma. Because TNF is known to cause new vessel formation, hemorrhagic necrosis and increased thrombogenicity, it may play a role in the evolution of uncomplicated to complex atheroma.

Hemodynamic and Metabolic Responses to Vasodilator Therapy in Acute Myocardial Infarction

Hemodynamic effects of vasodilator therapy (phentolamine or nitroprusside) were studied in 38 patients with acute myocardial infarction (AMI). Cardiac metabolism was studied in 19 of the 38 patients. According to the initial level of left ventricular filling pressure (LVFP) and left ventricular stroke work index (SWI), patients were divided into three groups: Group I-nine patients with LVFP 15 mm Hg or less; Group II-14 patients with LVFP > 15 mm Hg and SWI >20 g-m/m2; Group III-15 patients with LVFP > 15 mm Hg and SWI < 20 g-m/ m2. In Group I most patients were clinically uncomplicated. In Group IL most patients had clinical left ventricular failure including one patient who had clinical features of cardiogenic shock. Group III patients all had severe left ventricular failure, with eight patients in clinical shock.In all groups LVFP, pulmonary artery pressure, right atrial pressure, and systemic and pulmonary vascular resistance decreased significantly with vasodilator therapy with only a slight to moderate decrease in arterial pressure. In Group I patients SVI decreased (-7%) together with an increase in heart rate. Significant improvement in left ventricular performance, however, was observed in Groups II and III as indicated by increased stroke volume index (SVI) and cardiac index (CI) and decreased LVFP. The increase in SVI and CI was of similar magnitude in both Group LI (SVI +18%, CI +24%) and Group III (SVI +28%, CI +29%) patients, a change suggesting that vasodilation thereby may be applicable and beneficial even in the presence of severe depression of cardiac performance.Improved left ventricular performance in group II and III patients was accompanied by a slight decrease in coronary blood flow, myocardial oxygen consumption, and transmyocardial oxygen extraction. There was no change in myocardial lactate metabolism in any group. In vitro studies in isolated cat papillary muscle preparations showed no direct positive inotropic effect of either phentolamine or nitroprusside. Thus, significant improvement in left ventricular performance occurs during vasodilator therapy in patients with AMI and elevated LVFP, even in the presence of severe depression of cardiac performance. Furthermore, this improvement is not accompanied by increased metabolic cost. Vasodilator therapy, therefore, may have an important role in the treatment of pump failure complicating myocardial infarction.