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The presence of left ventricular outflow tract obstruction (LVOTO) of either a resting or dynamic nature may have important therapeutic and prognostic implications in patients with hypertrophic cardiomyopathy (HCM). Doppler echocardiograms combined with amyl nitrite (Amyl) inhalation were performed in 333 consecutive patients referred for suspected HCM to diagnose and categorize the nature and severity of LVOTO. Hypertrophic cardiomyopathy was present by 2-D and M-mode criteria in 145/333 (44 percent) patients. Normal limits of resting and post-Amyl continuous wave Doppler peak left ventricular outflow tract velocities were established in 15 subjects with completely normal 2-D and Doppler echocardiograms. Based on these criteria, of the 145 patients with HCM, 63 (43 percent) were classified as having resting LVOTO, peak velocity 4.2 ±1.3 m/s. Among 82 patients with HCM without resting LVOTO, 47 (57 percent) received Amyl. Latent LVOTO was provoked in 25/47 (53 percent), peak post-Amyl velocity 4.5 ± 1.2 m/s. The remaining 22 (47 percent) had nonobstructive HCM, as indicated by no significant increase in post-Amyl velocity. Among a total 62 subjects receiving Amyl, none experienced serious morbidity or mortality. Doppler echocardiography, in conjunction with Amyl inhalation in selected patients, is a useful noninvasive method to diagnose and categorize patients with HCM according to the nature and severity of LVOTO. (Chest 1990; 97:389–95)

This review describes the various aspects of the diagnosis of myocardial infarction coexisting with the Wolff-Parkinson-White syndrome. In this situation, the diagnosis of myocardial infarction is frequently difficult because the delta wave may obliterate the Q wave of infarction or may itself simulate infarction. ST-T wave abnormalities are notoriously unreliable in the evaluation of myocardial ischemia or infarction during preexcitation, although serial electrocardiograms showing evolution of primary changes occasionally provide important clues. The diagnosis of myocardial infarction becomes simple when normal conduction resumes and thus an attempt, including the use of drugs, should be made to abolish preexcitation. During preexcitation, left ventricular extrasystoles may unmask an infarcted area by restoring the initial negativity of the left ventricular cavity. The recognition of bundle branch or fascicular block in suspected myocardial infarction complicated by preexcitation is of more than academic interest since the anomalous bundle cannot be depended on to provide reliable A-V conduction should high grade A-V block develop in the normal pathway. Exercise stress testing has generally been considered unreliable in the evaluation of patients with Wolff-Parkinson-White syndrome.

We analyzed the use of amyl nitrite as a provocative factor in the diagnosis of mitral valve prolapse in a population of healthy young adults. Sixty-five men and 11 women underwent continuous M-mode echocardiographic and phonocardiographic monitoring before, during and after the administration of inhaled amyl nitrite. All of the 76 subjects had normal baseline echocardiograms, and all had a satisfactory hemodynamic response to amyl nitrite. Mitral valve prolapse, defined by echocardiography and phonocardiography, was not provoked in any of the subjects. Therefore, we concluded that, although this technique may be difficult, significant false-positive results should not occur if adherence to strict diagnostic criteria takes place.

To study the genesis of the systolic murmur of idiopathic hypertrophic subaortic stenosis (IHSS), phonocardiograms, echocardiograms, and pulsed Doppler echocardiography were done in 11 patients with IHSS. Seven had marked systolic anterior motion of the mitral valve (SAM) at rest (group 1); four had small SAM at rest but marked SAM was noted after amyl nitrite inhalation, (group 2). In all group 1 patients, marked turbulence was present during systole in the left ventricular outflow tract (LVOT). A lesser degree of turbulence was present in systole in the left atrium in six of seven patients. The turbulence in the LVOT and left atrium was increased by amyl nitrite, and decreased by handgrip. In group 2 patients, mild turbulence was present in the LVOT at rest, but none was noted in the left atrium. Amyl nitrite increased turbulence in the LVOT, and turbulence in the left atrium was noted in two patients. We conclude that the murmur of IHSS in patients with marked SAM is due to a composite of turbulence in the LVOT and mitral regurgitation, whereas when only mild SAM is present, the murmur originates in the left ventricular outflow tract.

False-negative supine M-mode echocardiograms occur in some patients with proved mitral valve prolapse. To investigate further, we performed M-mode echocardiography (MME) during standing and after the inhalation of amyl nitrite in 17 patients (group 1) selected for auscultatory evidence of mitral valve prolapse (MVP) but negative supine MME. To validate the standing MME technique, eight patients with classic auscultatory MVP with positive supine MME for MVP (group 2) and 15 control subjects (group 3) were studied. Supine cross-sectional echocardiography (CSE) was compared to MME in all three groups. Standing MME elicited echocardographic evidence of MVP in 14/17 (82 percent) of group 1—auscultatory evidence of MVP but negative supine MME; CSE demonstrated MVP in 8/13 (62 percent) of the same patients. There was no clear advantage of the CSE long axis view over the CSE apical four chamber view in the diagnosis of MVP in these selected subjects; however, the two views were complementary. Amyl nitrite was ineffective in eliciting echocardiographic evidence of MVP.

Myocardial ischemia is best viewed as a discrepancy between myocardial oxygen demands and availability of oxygen to the heart. Although the fundamental action of each nitrite is generalized direct vasodilation, in patients with coronary arterial disease the dynamic factor mediating favorable effects of these agents on angina pectoris appears largely to be reduction of myocardial oxygen requirements. Thus, the salutary effect of sublingual nitroglycerin is most related to venodilation which results in peripheral pooling of blood and reduction of heart size, thereby diminishing systolic wall tension and oxygen consumption of the ischemic left ventricle. With rapid introduction of nitrite into the circulation following inhaled amyl nitrite, marked direct peripheral arteriolar dilation results in decline of systolic tension and oxygen utilization of the heart and relief of myocardial ischemic pain. Thus, a peripheral circulatory mechanism of action of the nitrites is described which is immediately available for improvement of angina pectoris and is operative even in absence of coronary dilation.

T elemetry of phasic arterial flow velocity in man One hundred of the diseased group had the anatomic has been made possible with the development and ~ h ~ ~ i o l o g i c d agnosis established by right and left heart catheterization, selective cineangiocardiography and Of a 'Owmeter 'yStem by Frankselective indicator dilution curves. The remaining 33 palin and associates1-? and This technique tients who were not subjected t~ cardiac hernodynamic has provided an opportunity to study abnormalities studies had the usual clinical and laboratory evidence in of peripheral arterial flow velocity in health and keeping with their diseased states. diseased states using probes inserted around the Fifteen patient7 of the diseased group were sh~died in the Coronary Care Unit where continuous monitoring of the peripheral arteries On e ~ o s e d vestranscutaneous arterial blmd flow was obtained, s e l ~ . ' ~ l ~ Further technical devel~pments~,~ have A I ~ had the and laboratory evidence of acute myodemonstrated the potential usefulness of this techcardial infarction. niaue to study arterial flow velocitv of the unexFlow velocity curves were obtained at rest in all patients. vessel iying in close to the sh. In 47 patients, measurements of arterial flow velocity were made during spontaneous or catheter induced cardiac arhas been used b~ and c'rhythmias; in 37, fe. tion, recordings were made during administration of drugs hi^ is a review of our with (inhalation of amyl nitrite, intravenous administration of isoproterenol during coronary arteriography, before ant1 transcutaneous measurement Of peripheral after conversion of atria] fibrillation to sinus rhythm). flow velocity in normal subjects and in patients with The arterial monitoring sites in the 170 ~at ien t s included cardiovascular diseases. 138 examinations of brachial artery velocity at the level of

False-negative supine M-mode echocardiograms occur in some patients with proved mitral valve prolapse. To investigate further, we performed M-mode echocardiography (MME) during standing and after the inhalation of amyl nitrite in 17 patients (group 1) selected for auscultatory evidence of mitral valve prolapse (MVP) but negative supine MME. To validate the standing MME technique, eight patients with classic auscultatory MVP with positive supine MME for MVP (group 2) and 15 control subjects (group 3) were studied. Supine cross-sectional echocardiography (CSE) was compared to MME in all three groups. Standing MME elicited echocardiographic evidence of MVP in 14/17 (82 percent) of group 1--auscultatory evidence of MVP but negative supine MME; CSE demonstrated MVP in 8/13 (62 per cent) of the same patients. There was no clear advantage of the CSE long axis view over the CSE apical four chamber view in the diagnosis of MVP in these selected subjects; however, the two views were complementary. Amyl nitrite was ineffective in eliciting echocardiographic evidence of MVP.

The occurrence of systolic ejection sounds (SS) in idiopathic hypertrophic subaortic stenosis (IHSS) has been controversial. We examined the graphic studies of 42 patients with proved IHSS. Eight were felt to have early systolic “click-like” sounds. These sounds occurred only at times of significant hemodynamic subaortic obstruction and, in contrast to other ejection sounds, occurred at the time of the first peak of the carotid pulse. We conclude that early systolic sounds occasionally are present in IHSS, but their origin and nature are not similar to ejection sounds in other diseases.

The effect of amyl nitrite inhalation on the hemodynamics of sodden severe aortic regurgitation was studied during heart catheterization. At rest the left ventricular diastolic pressure equaled aortic pressure and exceeded left atrial pressure closing the mitral valve prematurely. Amyl nitrite inhalation transiently decreased the left ventricular diastolic pressure to the level of the left atrial pressure by reducing the degree of aortic regurgitation. This demonstrates that the severity of the aortic regurgitation is the major factor responsible for the abnormal hemodynamics observed in this condition.

To study the genesis of the systolic murmur of idiopathic hypertrophic subaortic stenosis (IHSS), phonocardiograms, echocardiograms, and pulsed Doppler echocardiography were done in 11 patients with IHSS. Seven had marked systolic anterior motion of the mitral valve (SAM) at rest (group 1); four had small SAM at rest but marked SAM was noted after amyl nitrite inhalation, (group 2). In all group 1 patients, marked turbulence was present during systole in the left ventricular outflow tract (LVOT). A lesser degree of turbulence was present in systole in the left atrium in six of seven patients. The turbulence in the LVOT and left atrium was increased by amyl nitrite, and decreased by handgrip. In group 2 patients, mild turbulence was present in the LVOT at rest, but none was noted in the left atrium. Amyl nitrite increased turbulence in the LVOT, and turbulence in the left atrium was noted in two patients. We conclude that the murmur of IHSS in patients with marked SAM is due to a composite of turbulence in the LVOT and mitral regurgitation, whereas when only mild SAM is present, the murmur originates in the left ventricular outflow tract.

Late systolic murmur with or without a mid-late systolic click has not been reported in patients with coronary artery disease. Eighteen patients are reported with both late systolic murmur and significant coronary artery disease. The latter manifested as either angina pectoris or myocardial infarction. Radiographic confirmation including selective coronary arteriography of obstructive coronary artery disease was obtained in all patients. Left ventriculography revealed systolic prolapse of the posterior and sometimes the anterior mitral leaflets with varying degrees of mitral regurgitation. Differentiation between the late systolic murmur associated with coronary artery disease and the noncoronary “auscultatory-electrocardiographic” syndrome is important, though sometimes difficult. The common denominator in both is an abnormal mitral valve apparatus. Late systolic murmur in coronary artery disease represents a mild form of papillary muscle dysfunction. The discovery of a late systolic murmur in association with chest pain and abnormal electrocardiogram in a middle-aged or older man should not be passed off lightly as “benign”. On the contrary, if it is associated with an accentuated first sound, presystolic and diastolic gallops, becomes softer after an extrasystole, and increases in intensity following inspiration, amyl nitrite inhalation or squatting, it should strongly suggest coronary artery disease and further diagnostic studies, including coronary arteriography, are indicated.