George A. Diamond

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.

Incremental Prognostic Value of Myocardial Perfusion Single Photon Emission Computed Tomography for the Prediction of Cardiac Death Differential Stratification for Risk of Cardiac Death and Myocardial Infarction

BACKGROUND The incremental prognostic value of stress single photon emission computed tomography (SPECT) for the prediction of cardiac death as an individual end point and the implications for risk stratification are undefined. METHODS AND RESULTS We identified 5183 consecutive patients who underwent stress/rest SPECT and were followed up for the occurrence of cardiac death or myocardial infarction. Over a mean follow up of 642+/-226 days, 119 cardiac deaths and 158 myocardial infarctions occurred (3.0% cardiac death rate, 2.3% myocardial infarction rate). Patients with normal scans were at low risk (< or =0.5%/y), and rates of both outcomes increased significantly with worsening scan abnormalities. Patients who underwent exercise stress and had mildly abnormal scans had low rates of cardiac death but higher rates of myocardial infarction (0.7%/y versus 2.6%/y; P<.05). After adjustment for prescan information, scan results provided incremental prognostic value toward the prediction of cardiac death. The identification of patients at intermediate risk of nonfatal myocardial infarction and low risk for cardiac death by SPECT may result in significant cost savings when applied to a clinical testing strategy. CONCLUSIONS Myocardial perfusion SPECT yields incremental prognostic information toward the identification of cardiac death. Patients with mildly abnormal scans after exercise stress are at low risk for cardiac death but intermediate risk for nonfatal myocardial infarction and thus may benefit from a noninvasive strategy and may not require invasive management.

Exercise Myocardial Perfusion SPECT in Patients Without Known Coronary Artery Disease Incremental Prognostic Value and Use in Risk Stratification

BACKGROUND We evaluated the incremental prognostic value, the role in risk stratification, and the impact on patient management of myocardial perfusion single-photon emission computed tomography (SPECT) in a population of patients without prior myocardial infarction, catheterization, or revascularization. METHODS AND RESULTS We examined 2200 consecutive patients who at the time of their dual-isotope SPECT had not undergone catheterization, coronary artery bypass surgery, or percutaneous transluminal coronary angioplasty and had no known history of previous myocardial infarction. Follow-up was performed at a mean of 566 +/- 142 days (97% complete) for hard events (cardiac death and myocardial infarction) and for referral to cardiac catheterization or revascularization within 60 days after nuclear testing. Examination of clinical, exercise, and nuclear models by use of pre-exercise tolerance test (ETT), post-ETT, and nuclear information using a stepwise Cox proportional hazards model and receiver-operating characteristic curve analysis revealed that nuclear testing added incremental prognostic value after inclusion of the most predictive clinical and exercise variables (global chi2 = 12 for clinical variables; 31 for clinical + exercise variables; 169 for nuclear variables; gain in chi2, P < .0001 for all; receiver-operating characteristic areas: 0.66 +/- 0.04 for clinical, 0.73 +/- 0.04 for clinical + exercise variables, 0.87 +/- 0.03 for nuclear variables, P = .03 for gain in area with exercise variables; P < .001 for increase with nuclear variables). Multiple logistic regression analysis revealed that scan information contributed 95% of the information regarding referral to catheterization with further additional information provided by presenting symptoms and exercise-induced ischemia. Referral rates to early catheterization and revascularization paralleled the hard event rates in all scan categories - very low referral rates in patients with normal scans and significant increases in referral rates as a function of worsening scan results. Even after stratification by clinical and exercise variables such as the Duke treadmill score, pre- and post-ETT likelihood of coronary artery disease, presenting symptoms, sex, and age, the nuclear scan results further risk-stratified the patient subgroups, thus demonstrating clinical incremental value. CONCLUSIONS In a patient population with no evidence of previous coronary artery disease at overall low risk (1.8% hard event rate), myocardial perfusion SPECT adds incremental prognostic information and risk-stratifies patients even after clinical and exercise information is known. It appears that referring physicians use this test in an appropriate manner in selecting patients to be referred to catheterization or revascularization.

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.

Coronary Artery Calcium Evaluation by Electron Beam Computed Tomography and Its Relation to New Cardiovascular Events

Electron beam computed tomography is widely used to screen for coronary artery calcium (CAC). We evaluated the relation of CAC to future cardiovascular disease events in 926 asymptomatic persons (735 men and 191 women, mean age 54 years) who underwent a baseline electron beam computed tomographic scan. All subjects included in this report returned a follow-up questionnaire 2 to 4 years (mean 3.3) after scanning, inquiring about myocardial infarction, stroke, and revascularizations. Sixty percent of men and 40% of women had a positive scan at baseline. Twenty-eight cardiovascular events occurred and were confirmed by blinded medical record review. The presence of CAC (a total calcium score of >0) and increasing score quartiles were related to the occurrence of new myocardial infarction (p <0.05), revascularizations (p <0.001), and total cardiovascular events (p <0.001). Those with scores at or above the median (score of 5) had a relative risk of 4.5 (p <0.01) for new events. From Cox regression models, adjusted for age, gender, and coronary risk factors, the relative risks for those with scores of 81 to 270 and -271 (compared with 0) for cardiovascular events were 4.5 (p <0.05) and 8.8 (p <0.001), respectively. These data support previous reports showing CAC to be a modest predictor of future cardiovascular events.

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.

Correlative classification of clinical and hemodynamic function after acute myocardial infarction

To characterize the relation between clinical and hemodynamic state in acute myocardial infarction, 200 patients with acute infarction were evaluated with clinical and hemodynamic criteria. Patients were classified clinically on the basis of peripheral hypoperfusion (hypotension, tachycardia, confusion, cyanosis, oliguria) and pulmonary congestion (rales, abnormal chest roentgenogram). Four clinical subsets were defined that correlated with cardiac index (Cl, liters/min per m2) and pulmonary capillary pressure (PCP, mm Hg): (see article). Parallel hemodynamic subsets were developed independently on the basis of depressed cardiac index (2.2 liters/min per m2 or less) and elevated pulmonary capillary pressure (greater than 18 mm Hg). The rate of accuracy of clinical examination in predicting hemodynamic abnormalities was 83 percent. Mortality rates were similar in the clinical and hemodynamic subset calssifications, averaging 2.2 percent in subset I, 10.1 percent in subset II, 22.4 percent in subset III and 55.5 percent in subset IV. Drug interventions in the course of hospitalization resulted in a 38 percent increase in depressed cardiac index and 34 percent decrease in elevated pulmonary capillary pressure. Resolution of clinical abnormalities paralleled this hemodynamic improvement in 70 percent of patients. These data suggest that clinical performance and both clinical and hemodynamic subsets are directly relevant to establishing prognosis and the selection of therapy in patients with acute myocardial infarction.

The declining specificity of exercise radionuclide ventriculography.

Although exercise radionuclide ventriculography was initially reported to be a highly specific test for coronary-artery disease, later studies reported a high false-positive rate. To verify this turnabout, we analyzed the responses in 77 angiographically normal patients; 32 were studied from 1978 to 1979 (the early period), and 45 from 1980 to 1982 (the recent period). Most patients studied in the early period had normal responses (94 per cent for ejection fraction and 84 per cent for wall motion). In contrast, normal responses were less frequent in patients studied in the recent period (49 per cent for ejection fraction and 36 per cent for wall motion, P less than 0.001). The probability of coronary disease before testing was higher in these patients (38 vs. 7 per cent, P less than 0.001). More patients studied in the recent period underwent radionuclide ventriculography before angiography (78 vs. 22 per cent, P less than 0.001), and more of these prior studies had abnormal results than those performed after angiography (55 vs. 6 per cent, P less than 0.0001). Thus, two factors are responsible for the temporal decline in specificity: a change in the population being tested (pretest referral bias) and a preferential selection of patients with a positive test response for coronary angiography (post-test referral bias).

Effect of Coronary Artery Disease and Acute Myocardial Infarction on Left Ventricular Compliance in Man

The evaluation of left ventricular (LV) compliance by use of the pressure-volume (P-V) relationship encounters several serious difficulties. Since the P-V relationship is curvilinear, it is difficult to quantitate. Furthermore, alterations of resting heart size and geometry also produce marked changes in the P-V curve. The first derivative of the P-V relationship, however, is a precisely linear function expressed by the formula dP/dV = aP+b. The slope of this linear function, a, termed the passive elastic modulus, has been shown to be independent of initial volume and primarily and predominantly determined by changes in the stiffness of the myocardium. Myocardial wall stiffness was evaluated in three groups of subjects during LV catheterization. In 13 normal subjects a = 0.005; in 13 with coronary artery disease a = 0.011; and in 12 with acute infarction a = 0.045. The differences in stiffness among the groups were highly significant (P < 0.005).It was concluded that a measurable change in ventricular compliance occurs with the development of coronary artery disease and that a further increase in wall stiffness occurs with the development of acute infarction. The magnitude of increase in LV wall stiffness correlated directly with immediate prognosis: 87% of those subjects with a &Dgr;P/&Dgr;V greater than 0.5 mm Hg/cc died of power failure during the acute stage of their illness. These alterations in compliance may invalidate certain traditional concepts of LV function and heart failure.

ACCF 2012 Expert Consensus Document on Practical Clinical Considerations in the Interpretation of Troponin Elevations: A Report of the American College of Cardiology Foundation Task Force on Clinical Expert Consensus Documents

This document has been developed as an Expert Consensus Document (ECD) by the American College of Cardiology Foundation (ACCF), American Association for Clinical Chemistry (AACC), American College of Chest Physicians (ACCP), American College of Emergency Physicians (ACEP), American College of