Markus Jakob

Tortuosity of coronary arteries in chronic pressure and volume overload.

The role of coronary tortuosity in the pathophysiology of chronic pressure and volume overload is still unclear. A new method for measuring coronary tortuosity in patients with chronic pressure and volume overload was evaluated in 62 patients. Sixteen controls, 14 patients with arterial hypertension, and 32 patients with aortic regurgitation were included in the present analysis. The left anterior descending (LAD) and circumflex (LCX) coronary arteries were traced, and tortuosity was determined in the 30 degrees right (RAO) and 60 degrees left (LAO) anterior oblique projection. Tortuosity index (TI, %) was defined as the percent ratio of calculated shortest distance divided by total length of the coronary artery. TI was 104.1 +/- 3.2% at end-diastole in controls, 105.7 +/- 3.8% in hypertensives (P < 0.05 vs. controls), and 102.9 +/- 2.5% in patients with aortic regurgitation (P < 0.05 vs. controls, P < 0.001 vs. hypertensives). Respective values at end-systole were 107.8 +/- 4.7% in controls, 109.8 +/- 7.1% in hypertensives (ns vs. controls), and 104.3 +/- 3.3% in patients with aortic regurgitation (P < 0.001 vs. controls and vs. hypertensives). No differences were found in tortuosity between RAO and LAO projection or between LAD and LCX artery. There was a significant correlation between TI and left ventricular (LV) muscle mass, LV volume, and age. Females tended to have more tortuous vessels than males. Coronary tortuosity is more pronounced in patients with chronic pressure than with volume overload. Determinants of coronary tortuosity are gender, age, LV volume, and muscle mass. Thus, coronary tortuosity seems to play an important role as a physiologic determinant for the flow and the mechanics of the vessel wall.

Left ventricular diastolic dysfunction late after coarctation repair in childhood: Influence of left ventricular hypertrophy

OBJECTIVES Left ventricular systolic and diastolic function were evaluated late after successful operation for aortic coarctation in childhood. BACKGROUND Persistent arterial hypertension and left ventricular hypertrophy after coarctation repair might impair left ventricular function. METHODS Biplane angiography and simultaneous high fidelity pressure measurements were performed in 12 patients 3 to 12 years postoperatively (residual pressure gradient 4 mm Hg). Eight patients were normotensive and four had borderline hypertension. Data at rest and after nitroprusside infusion (1.7 micrograms/kg per min) were evaluated and compared with data from 12 control subjects. RESULTS Systolic left ventricular function (ejection fraction-end-systolic wall stress relation) was normal in all patients. However, left ventricular muscle mass (113 vs. 86 g/m2), right atrial pressure (5.2 vs. 1.9 mm Hg) and left ventricular end-diastolic pressure (16 vs. 11 mm Hg) were significantly higher in patients than in control subjects. There was a linear relation between muscle mass and left ventricular end-diastolic (r = 0.66, p < 0.001) or right atrial (r = 0.60, p < 0.01) pressure. Left ventricular relaxation and myocardial stiffness were normal. However, there was an upward shift of the diastolic pressure-volume curve when compared with control values, but this shift was reversed by the administration of nitroprusside. CONCLUSIONS Systolic function is normal late after coarctation repair. However, diastolic function can be abnormal with an upward shift of the diastolic pressure-volume curve that is reversed by nitroprusside administration and is probably due to residual left ventricular hypertrophy.

Vibration, Acceleration, Gravitation, and Movement: Activity Controlled Rate Adaptive Pacing During Treadmill Exercise Testing and Daily Life Activities

Activity‐based sensors for rate adaptive pacing have been available for several years and now include several different types: vibration; acceleration; gravitation; and movement. However, a systematic comparison evaluating the relative advantages and disadvantages of these various sensors has received little study. The purpose of the present study was to compare these sensor subtypes using treadmill testing and an outdoor test circuit, which simulated daily life activities and included both uphill and downhill walking. Pacemakers were strapped on the chest of healthy volunteers and connected to one channel of an ambulatory recording device, which also recorded the subjects intrinsic heart rate. The pacemakers were programmed using an initial treadmill test to standardize the rate responsive parameters for each device. Nine different pacemaker models were studied including 3 vibration‐based (Elite. Synchrony, Metros). 4 acceleration‐based (Relay, Excel, Ergos, Trilogy), 1 gravitational‐based (Swing), and 1 movement‐based (Sensorithm) device. All devices demonstrated a prompt rate response with casual walking on flat ground. The vibration‐, gravitational‐, and movement‐based pacemakers showed a pronounced rate decline during more strenuous work, e.g., walking uphill. This phenomenon was absent in the accelerometer‐based units. In particular, the vibration‐ and movement‐based units showed a higher rate with walking downhill compared to uphill. An optimally tuned rote behavior on the treadmill usually did not provide an optimal rate behavior during daily activities and there was a tendency to overstimulation during low workload. The development of the two newest sensors (gravitational and movement) did not result in an improved performance of rate response behavior. Overall, the accelerometer‐based pacemakers simulated or paralleled sinus rate behavior the most closely.

Right ventricular diastolic function-during exercise: Effect of ischemia☆

The effects of exercise on right ventricular diastolic function were evaluated in 14 patients who underwent supine rest and exercise right ventricular angiography. On the basis of coronary anatomy and exercise left ventricular regional wall motion analysis, these patients were classified into two groups: Group 1 (n = 7) had no or only mild coronary artery disease and Group 2 (n = 7) had significant coronary disease and exercise-induced left ventricular wall motion abnormalities suggesting ischemia. Chamber stiffness at rest was higher in Group 2 (48 x 10(-3) ml-1/m2) than in Group 1 (18 x 10(-3) ml-1/m2, p = 0.006). During exercise, right ventricular filling rate in the second half of diastole was significantly lower in Group 2 (126 versus 276 ml/m2 per s, p less than 0.03). The time constant of right ventricular pressure decay decreased significantly in both groups with exercise; however, both groups displayed a parallel upward shift of the pressure-volume curve with exercise. Because ischemia could not be demonstrated in Group 1, it is an unlikely explanation for this shift. Septal shifting was not a significant factor with exercise. Because of an increase in left ventricular end-diastolic volume with exercise and a close correlation between right and left ventricular end-diastolic pressures (r = 0.96 for Group 1 and r = 0.76 for Group 2), pericardial constraint is the most likely cause for this upward shift of the pressure-volume curve. Therefore, an increase in right ventricular end-diastolic pressure may not be a reliable indicator of ischemia during exercise because this pressure is coupled to changes in left ventricular volume and pericardial constraint.

Reduced Epicardial Coronary Vasodilator Capacity in Patients With Left Ventricular Hypertrophy

BACKGROUND Enlargement of the epicardial coronary arteries occurs in left ventricular (LV) hypertrophy as an adaptation to the increased coronary blood flow. METHODS AND RESULTS Vasodilator capacity of the epicardial coronary arteries was determined in 44 patients. The dose-response relation of intracoronary nitroglycerin was assessed in 14 patients (7 control subjects and 7 patients with aortic stenosis [study A]) using quantitative coronary angiography. In a second study (B), vasodilator capacity of the epicardial coronary arteries was determined in 15 control subjects and 15 patients with valvular heart disease. In study A, a curvilinear dose-response relation with maximal vasodilation after 90 micrograms intracoronary nitroglycerin was found in both control subjects and patients with aortic stenosis. Vasodilator capacity was reduced in those with aortic stenosis, although sensitivity to nitroglycerin was similar in both groups. In study B, coronary circumferential length at baseline was larger in those with LV hypertrophy (12.2 +/- 2.2 mm) than in control subjects (8.6 +/- 1.5 mm; P < .001); after 100 micrograms intracoronary nitroglycerin, it increased to 12.9 +/- 2.2 mm (6 +/- 5%) in those with LV hypertrophy and to 10.3 +/- 1.5 mm (21 +/- 8%; P < .001) in control subjects. An inverse relation between baseline circumferential length and its percent increase after nitroglycerin was found (r = -.71, P < .001). CONCLUSIONS Vasodilator capacity of the epicardial coronary arteries is reduced in patients with LV hypertrophy, although sensitivity to nitroglycerin is normal. This may be due to a flow-mediated decrease in coronary vasomotor tone and/or the occurrence of vascular remodeling with an enlargement of the coronary arteries.

Right ventricular systolic function during exercise with and without significant coronary artery disease

To evaluate the effects of exercise and coronary artery disease on right ventricular (RV) systolic function, rest and exercise biplane RV angiograms were recorded in 20 patients undergoing diagnostic cardiac catheterization. Thirteen patients had exercise angiograms of sufficient quality to undergo analysis and were classified into 2 groups. Group 1 had no or only mild coronary artery disease; group 2 had significant coronary artery disease as manifested by new, exercise-induced, left ventricular regional wall motion abnormalities. RV systolic pressure increased in both groups during exercise: 33 to 57 mm Hg in group 1 (p = 0.0002) and 33 to 55 mm Hg in group 2 (p = 0.0004). Pulmonary resistance did not change in group 1 during exercise but increased in group 2 (3.2 to 4.8 Wood units, p = 0.04). RV ejection fraction increased slightly, but not significantly, during exercise in group 1, but decreased in group 2 (73 vs 58% with exercise [p = 0.01]). The change in RV ejection fraction from rest to exercise correlated closely with the change in pulmonary resistance from rest to exercise (r = -0.89, p less than 0.0001). RV regional wall motion analysis demonstrated a generalized decline in regional ejection fraction in group 2 during exercise, even in patients without right coronary artery disease. In conclusion, there is a decline in RV ejection fraction during exercise in patients with significant coronary artery disease. The generalized reduction in regional RV ejection fraction coupled with the close correlation with the change in pulmonary resistance suggests that increased afterload, rather than RV ischemia, is the cause.

Position control of intravascular Doppler guidewire: Concept of a tracking indicator and its clinical implications

Intracoronary Doppler ultrasound guidewires (DGW) utilize a wide ultrasound beam combined with a measurement of the spectral peak velocity to estimate the spatial peak velocity within a blood vessel. However, the spectral peak velocity may underestimate the true spatial peak velocity if the DGW is not properly positioned. The purpose of this study was to find a Doppler-derived parameter that would aid in the optimal positioning of the DGW within the vessel lumen. We studied the relationship between the time-averaged, spectral-peak velocity (APV) and the normalized first Doppler moment (M1/M0) to develop a DGW position indicator and demonstrate its clinical utility. In vitro, heparinized, human whole blood with a hematocrit of 45% was directed from a reservoir via a roller pump into four serially connected straight silicone tubes of known diameter (2.5, 3.0, 3.5, 4.0 mm). A DGW was inserted into the tubes where simultaneous APV and M1/M0 measurements were obtained for flow rates ranging from 49 to 316 ml/min. Optimal positioning of the DGW was identified at the position where maximum APV and M1/M0 were obtained. With optimal positioning the correlation between APV and M1/M0 was good (APV = 1.62 M1/M0 + 5.0; R2 = 0.98). Importantly, this correlation showed no dependence on the tube diameter. In vivo, in four patients APV and M1/M0 measurements were obtained in 16 coronary artery segments in one left anterior descending, two circumflex, and two right coronary arteries. In 10 vessel segments, there was no discrepancy between the measured and expected M1/M0 after positioning the DGW with help of the Doppler signal quality only. In six vessel segments, repeat DGW positioning using M1/M0 was necessary, yielding an average increase of APV of 20% (7-38%). We conclude that DGW positioning can be optimized using the correlation between APV and M1/M0 as a reference. For any given APV value, there is a corresponding expected value for M1/M0 under the condition of optimal positioning. Any discrepancy between the measured and expected values for M1/M0 then indicates suboptimal positioning.

Coronary pseudoaneurysm: Diagnosis by intravascular ultrasonography

A pseudoaneurysm after percutaneous coronary angioplasty (PTCA) of the left anterior descending coronary artery is reported in a 52-year-old woman who underwent PTCA for exertional angina and a significant isolated stenosis of the left anterior descending coronary artery. Intravascular ultrasonography during repeat coronary angiography clearly identified a localized coronary dilation at the PTCA site in conventional coronary angiography as a pseudoaneurysm that was confirmed during surgery.

Idiopathic Hypereosinophilic Vasculitis

This 36-year-old male patient, at the age of 22 years, had had painless scalp swelling due to multiple aneurysms of the left temporal artery. Biopsy revealed an eosinophilic infiltration of all three wall layers with fresh fibrinoid necrosis beside old fibrous scars. An idiopathic blood eosinophilia was noted; no treatment was initiated. In the present case, the 36-year-old patient presented with dyspnea at rest. The ECG showed evidence of prior inferior infarction. Transesophageal echocardiography found left ventricular (LV) enlargement with biplanar ejection fraction of 20% as well as dilatation of the right ventricle and the atria. LV muscle mass was increased (245 g/m2; normal, 134 g/m2). The epicardial coronary arteries showed grotesque aneurysmal …

Determinants of left ventricular diastolic function during myocardial ischemia: influence of myocardial structure and pericardial constraint.

ObjectiveTo assess the influence of myocardial structure and pericardial constraint during exercise ischemia on regional left ventricular passive elastic properties. MethodsLeft ventricular regional function was assessed at rest and during exercise using biplane angiography and high-fidelity pressure measurements. Twenty patients with either normal (n = 7) or stenotic coronary arteries (n = 13) were studied before and after successful bypass surgery. At the time of surgery, left ventricular transmural biopsies were taken from a normally perfused and a hypoperfused left ventricular region. ResultsRegional stiffness increased in the ischemic zone during exercise, but remained unchanged after revascularization. Regional fibrosis was significantly enhanced in the ischemic region compared with that in the normally perfused zone. No correlation was found between structural data and regional passive elastic properties, but there was a significant correlation between right atrial pressure and the asymptote of the diastolic pressure-volume relationship. ConclusionsAcute regional diastolic dysfunction can be observed during exercise in patients with coronary artery disease. Structural changes seem to have a minor role in the occurrence of diastolic dysfunction in the absence of myocardial infarction. The observed upward shift of the pressure-volume relationship during ischemia can be attributed to pericardial constraint that is manifested by an increase in right atrial pressure. Coronary Artery Dis 9:239–248