J. M. Foerster

Identification of Sudden Death Risk Factors in Acute and Chronic Coronary Artery Disease

Because of their potential role in the pathogenesis of sudden death, cardiac arrhythmias in patients with coronary artery disease have become the subject of increasing concern and investigation. A series of studies on the problem of ventricular ectopy as it relates to the entire spectrum of sudden death in coronary disease were carried out utilizing continuous portable electrocardiographic monitoring systems. Evaluation of arrthymias during the entire 3 week in-hospital period after acute myocardial infarction in 83 patients revealed that absence of premature ventricular contractions, including their serious forms (multifocal, paired, R on T phenomenon, frequency 5/min or greater) and ventricular tachycardia in the coronary care unit did not exclude their high incidence rate (premature ventricular contractions 30 percent, serious forms 41 percent, ventricular tachycardia 6 percent) in the late hospital phase. Because late hospital serious forms of ventricular ectopy correlated with arterial hypoxia and elevated left ventricular filling pressure in the coronary care unit and with persistent S-T abnormalities, the extent of left ventricular dysfunction and ischemia with acute myocardial infarction appeared precursors to these arrhythmias. Study of ventricular ectopy in the late hospital phase of acute myocardial infarction indicated that ventricular ectopy and particularly its serious forms and prognostic significance relative to subsequent sudden death after discharge; the extent of predischarge S-T segment alterations was greater in subjects who died suddenly than in survivors, suggesting that persistent ischemia or segmental dyssynergy, or both, predisposed to lethal arrhythmias. Among 86 patients with chronic coronary disease documented by catheterizerization, 87 percent had ventricular ectopy and 62 percent serious ventricular arrhythmias, in contrast to 34 percent and 9 percent, respectively in normal subjects; frequency of serious forms of ventricular ectopy was related to extent of coronary atherosclerosis. Correlation of standard electrocardiograms with continuous Holter electrocardiograms in 101 patients with chronic coronary disease over 24 months revealed that the former modality was insensitive in arrhythmia detection; patients free of ventricular ectopy by serial standard electrocardiograms had a 62 percent incidence rate of serious forms of ventricular ectopy and 6 percent ventricular tachycardia on portable continuous monitoring. Additional studies of patients with chronic coronary disease showed that assessment of both the type of ventricular ectopy and the setting in which it occurs provides the most meaningful characterization of risk of sudden death. These systematic series of observations identify premature ventricular ectopic beats as important and separate risk factors in coronary disease...

Determination of Blood Flow through Arteriovenous Fistulae and Shunts

A videodensitometric method for estimating relative flow was employed in a patient with a bovine arteriovenous fistula. Analogous arteriovenous communications of different sizes were created in two dogs for comparison. Local and general hemodynamic parameters were measured. The videodensitometric method proved to be highly accurate compared to electromagnetic flow readings and is the method of choice in estimating shunt flow in connection with routine angiography.

Angiographic determination of splanchnic blood flow.

A new videodensitometric method of measuring blood flow in the splanchnic arteries as a fraction of the cardiac output was compared to electromagnetic flow readings in dogs. A previous investigation regarding the accuracy of the method in vitro was extended to prove that the videodensitometric technique was highly accurate also in vivo. The simplicity of the technique suggests that the videodensitometric method could be used to estimate blood flow in splanchnic arteries during routine angiography.

Angiographic measurement of coronary blood flow by video dilution technique.

A simplified video dilution technique has been developed whereby neither coronary dimensions nor contrast velocity need be measured to obtain coronary blood flow relative to a control flow. In 6 dogs, the distal left anterior descending coronary artery flow was measured by simultaneous electromagnetic flowmeter and video dilution technique. For the 236 paired measurements, the electromagnetic flow ranged from 23 to 196 ml/min for each series. When the first measure of a series was considered the control, the flow ratio difference between electromagnetic and video dilution values had a standard deviation of 12 per cent. When each series was broken into pairs, flow ratio difference between these values had a standard deviation of 10 per cent. Thus, the video dilution technique allows accurate measurement of coronary blood flow relative to a control state, utilizing only the known amount of contrast medium injected and the image from videotape replay of the injection. A patient is presented to illustrate the technique during coronary angiography. Applications include determination of coronary reserve during reactive hyperemia to assess the hemodynamic significance of coronary lesions, and determination of the effects of drugs upon coronary blood flow.

New videodensitometric method for measuring renal artery blood flow at routine arteriography: validation in the canine model.

A contrast medium was injected in the aortic arch and selectively in a renal artery to estimate the renal blood flow as a percentage of the cardiac output by the videodensitometric (VD) method. Twenty-six paired VD measurements in four mongrel dogs were obtained and the results compared to electromagnetic (EM) flow readings from the aortic arch and a renal artery. The relative renal blood flow estimated by the VD method averaged 9.1% and correlated with the EM flow average of 9.6% with r = 0.96. Previous in vitro investigations of relative flow in a model have now been validated in vivo. These results suggest that videodensitometry could be a clinical tool for measuring renal blood flow in conjunction with routine arteriography.

Renal Artery Blood Flow Assessed by Video Dilution Technique before and after Percutaneous Transluminal Angioplasty

Successful percutaneous transluminal angioplasty was performed in 3 cases of renal artery stenosis where the effect upon renal blood flow was quantified by video dilution technique. This technique adds important information to pressure gradients and renin assays obtained during the dilatation procedure.

Comparative evaluation of the efficacy of intravenous nitroglycerin and nitroprusside on reducing ventricular ischemia measured by vectorcardiographic-ST magnitude in experimental porcine myocardial infarction

COMPARATIVE EVALUATION OF THE EFFICACY OF INTRAVENOUS NITROGLYCERIN AND NITROPRUSSIDE ON REDUCING VENTRICULAR ISCHEMIA MEASURED BY VECTORCARDIOGRAPHIC-ST MAGNITUDE IN EXPERIMENTAL PORCINE MYOCARDIAL INFARCTION James M. Foerster, MD; Zakauddin Vera, MD; David Janzen, BS; Dean T. Mason, MD, FACC, Univ. of Calif., Davis, Calif. Controversy remains concerning clinical effects of nitroglycerin (NTG) and nitroprusside (NP) on extent of muscle damage with acute myocardial infarction (AMI). To evaluate influence of these two vasodilators on degree of such muscle injury, vectorcardiographic-ST magnitude rise (STM) was used to estimate myocardial ischemia that occurred with AM1 in the intact porcine heart, the coronary circulation of which is similar to man. Previously we have shown the Frank XYZ leads ST sum correlates closely with ST sum of multiple epicardial grid leads. In ten pigs, following thoracotomy and coronary ligature, the chest was closed and Frank XYZ leads obtained. Natural evolution of STM over 4 hours was observed in four animals, and in six pigs NTG and NP dose-responses were obtained following AMI. In pharmacologic treated animals, hemodynamics and STM were recorded 30-60 minutes after coronary ligation (pre-drug control) and then remeasured after either NTG or NP; each animal was used as its own control with time allowed between each drug for return of control hemodynamics. Control BP at LVFP at Min STM m LVFP Min STM Min STM attained NTG 103 22 76 21 +81% NP 109 26 82 17 +66% Min STM = minimum STM rise; p = mean blood pressure (mm Hg); LVFP = left ventricular filling pressure (mm Hg). These data indicate that both NTG and NP C ischemia extent in experimental AMI. Moreover, with 4 LVFP, NP appears more effective than NTG in + ischemia with AMI. ATTENUATION OF THE CARDIOVASCULAR EFFECTS OF NITROGLYCERIN BY INDOMETHACIN. Esteban Morcillo, M.D. Bertram Pitt, M.D. and Philip R. Reid, M.D. Johns Hopkins Medical Institutions, Baltimore, Maryland. An earlier report from this laboratory demonstrated that nitroglycerin (TNG) produced a marked increase in myocardial prostaglandins E release when given as a carstant infusion (IOk Kanu Chatterjee, MD, FACC; William Parmley, MD, FACC; Anne Norman, BA: University of California, San Francisco, California. Vasodilators have an established role in the therapy of heart failure. Recent studies have demonstrated hemodynamic improvement in chronic congestive heart failure with oral hydralazine and most recently oral prazosin. This study compares the hemadynamic effects of hydralazine (HD) and prazosin (PR) in the same patients with chronic heart failure. Changes in heart rate (HR), mean arterial pres8ure (MAP), pulmonary artery pressure. pulmonary capillary wedge pressure (PCW), right atria1 pressure, cardiac index (CI), stroke volume index (SVI), stroke work index (WI), systemic (SVR) and pulmonary vascular resistance were determined in 12 patients after 3. 4 and 5 mg of PR and compared to initial control hemodynamics (Cl). After second control hemodynamics (C2) the effects of 75 mg oral HD were determined in the same patients. The results were: MAP PCW CI SVI SW1 HR mHg mHg L/minim2 ml/m2 g *m/m2 SVR* Cl 86?7 07?3 24fl 2.1k.l 26?2 22t3 1776? 8.5 PR-5 mg 07+7 79+3 19?2 2.52.2 3023 25t3 141Ot118 C2 87f7 87?3 2421 2.12.1 2522 22t2 1760+ 86 HD 89f6 7922 2021 3.32.2 3823 3022 10452 60 PR increasedC1 by 19% and decreased SVR by 21%. while in these patients HD increaaedC1 by 52% and decreased SVR by 41%. There was no change in other hemodynamic parameters with either drug. Conclusion: These findings suggest that both PR and HD produce beneficial hemodynamic response and within prescribed doses, HD is twice as effective as PR.

Vasodilator response in the lower extremity induced by contrast medium. III. Before and after percutaneous transluminal angioplasty

A standardized test series of contrast medium injections was performed in the iliac and femoral arteries to evaluate the immediate effect of percutaneous transluminal angioplasty. The vasodilator response recorded by video dilution technique was correlated to radiographic anatomy and symptomatology. Discrepancy between anatomic success and clinical relief of symptoms was found in 26 per cent of the dilatations. The severity of disease at the trifurcation was more marked in combination with femoral lesions than with corresponding iliac lesions. Rest pain was a common symptom with femoral lesions and rare with iliac lesions. Resting blood flow increased significantly after femoral dilatation but was unaffected by iliac dilatations. The video dilution technique provided an accurate staging of the severity of obstructive disease, and was an excellent predictor of subsequent symptomatic success or failure of percutaneous transluminal angioplasty.