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Biomedical subjects

F K Nakhjavan

Publications and source records attributed to F K Nakhjavan.

At least 37 records · Page 2Linked to original sources
PubMed1976

Spontaneous variations in atrioventricular conduction in pre-excitation.

Atrial pacing in a patient with a Wolff-Parkinson-White syndrome pattern showed unusual variability in AV nodal conduction time. Changes in the AV nodal conduction time occurred predominantly at paced rates in excess of 100/min and consisted of abrupt or gradual decreases in the AH interval. Such decreases resulted in unexpected normalization of the QRS pattern. In addition, pacing also revealed evidence of block in the accessory pathway. Such changes in atrioventricular conduction may account for the known variability of the QRS pattern in patients with the WPW syndrome. Further, they may also explain the benign clinical course in this patient.

Adult↗
PubMed1976

The relationship between prolapsing mitral leaflet syndrome and angina and normal coronary arteriograms.

Patients with a prolapsing mitral leaflet frequently have chest pain while their coronary arteriograms are normal. In this regard, these patients are similar to the group of patients with angina and normal coronary arteriograms. In the present study, clinical, electrocardiographic, cardiac hemodynamic, angiographic, and metabolic findings in 20 patients with a prolapsing mitral leaflet were compared to those of 16 patients with angina and normal coronary arteriograms. Except for the presence of mitral leaflet prolapse and systolic clicks, the findings were similar in both groups. We postulate that prolapsing mitral leaflet is probably related to two different mechanisms. In one the primary pathologic change is in the mitral valve (mainly myxomatous transformation), and the abnormalities of ventricular contraction are secondary to unloading of the heart because of a volume shift into the distended and enlarged mitral leaflets. In the other group, the primary pathologic change is in the myocardium, with secondary prolapse of the mitral valve. The myocardial abnormality itself is probably related to primary underlying myocardial disease or to arteriolar pathologic changes. The latter group has probably the same pathophysiologic abnormality as patients with angina and normal coronary arteriograms.

Adult↗
PubMed1975

Myocardial lactate metabolism during isometric hand grip test. Comparison with pacing tachycardia.

Twenty-five patients with chest pain were studied by left ventriculography and coronary arteriography. Myocardial metabolic studies were done during control state, pacing tachycardia, isometric hand grip at 30 per cent of maximum force, and combined hand grip plus pacing tachycardia. Nine patients had myocardial lactate abnormality (group 1) as evidenced by myocardial lactate production or decreased extraction (less than 10%). Though tension time index and triple product (left ventricular ejection time times HR times systolic pressure) as determinants of myocardial oxygen consumption were highest during combined hand grip plus pacing tachycardia, myocardial lactate abnormalities were most frequent during pacing tachycardia. The present study indicates that isometric hand grip even if performed during pacing tachycardia is not a sensitive test for detection of myocardial lactate abnormalities. The rising level of arterial lactate during isometric hand grip is the most likely mechanism of positive myocardial arteriovenous lactate difference.

Blood Pressure↗
PubMed1975

Comparison of ejection fraction and zonal mean velocity of myocardial fiber shortening.

To determine the extent of cardiac involvement until a diminished ejection fraction (EF) is present, zonal mean velocity of circumferential fiber shortening (Vcf) was measured from the left ventriculogram in 36 patients. The longitudinal axis (apex to mid-point of the aortic valve plane) in right anterior oblique view was divided into four equal parts by three perpeendicular chords. Zonal Vct and percent shortening along the proximal, middle and distal chords were measured. The results of this study indicate that a normal EF is frequently associated with a reduced Vct in one or even two zones. A reduced EF is generally accompanied by a diminished Vct in all three zones of the heart. In addition, a close correlation was found between zonal Vct and percent shortening. Hence the latter, which is much simpler to measure, can be instead of Vct Ejection fraction as a measure of myocardial performance is not as sensitive as Vct, especially in hearts with asynchrony of contraction.

Angiocardiography↗
PubMed1975

Myocardial metabolic studies in prolapsing mitral leaflet syndrome.

Patients with prolapsing mitral leaflet syndrome (PML) frequently have chest pain of undetermined etiology. Twenty-three patients with PML underwent cardiac hemodynamic, angiographic, and metabolic studies. The latter were performed during control spontaneous heart rate and tachycardia by right atrial pacing. Myocardial supply-demand ratio (DPTI:SPTI) was estimated from the planimetric integration of the diastolic area (diastolic pressure time index = DPTI) and systolic area (systolic pressure time index = SPTI) of the central aortic pressure. Chest pain during pacing occurred in five patients. In two patients, it was associated with ST depression typical of ischemia on the electrocardiogram. Myocardial lactate abnormalities (lactate production or less than 10% extraction) occurred in seven patients during pacing tachycardia and was present in two patients during control state. DPTI:SPTI ratio during control state was 1.22 (+/- 0.07 SE) and decreased to 0.85 (+/- 0.05 SE) during pacing tachycardia. It is concluded that the myocardial lactate abnormalities in PML, which were present in approximately 30% of the patients in the present series, are most likely due to myocardial hypoxia. Whether or not the hypoxia is secondary to "small vessel disease" is not elucidated by this study.

Adult↗
PubMed1975

Aortocoronary vein graft surgery in a cadaver kidney transplant recipient.

A case of Prinzmetal angina occurred in a recipient of a cadaver kidney transplant who was treated with aortocoronary vein graft. The patient had severe retrosternal chest pain associated with ST-segment elevation in the precordial leads. Coronary arteriograms disclosed two major lesions in the proximal anterior descending artery. Aortocoronary vein graft was successfully performed with no untoward effect on the renal status. The patient has been free of angina approximately two years postoperatively.

Adult↗