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Title: Cardiac cryosurgery: regional myocardial blood flow of ventricular cryolesions

Abstract

Cryosurgery is one of three methods introduced recently for the treatment of ventricular tachyarrhythmias. Cryothermic exposure ablates arrhythmogenic ventricular myocardium, and produces a dense fibrous scar with a sharp border to histologically normal tissue. Myocardial blood flow in the region of the cryolesion, however, has not been quantitated. The purpose of this study was to measure regional blood flow within and around the cryolesion in an attempt to identify ischemic zones that might become arrhythmogenic. Left ventricular cryolesions were created in eleven adult dogs. Two weeks later, the animals underwent radioactive tracer microsphere injection for quantitation of regional myocardial blood flow. The fibrotic cryolesion demonstrated a significantly depressed blood flow (0.44 +/- 0.07 ml/min/g) compared to blood flow in control tissue (1.36 +/- 0.12 ml/min/g) (P less than 0.001). A 1-mm strip of myocardium immediately adjacent to the cryolesion, as well as other myocardium surrounding and subjacent to the cryolesion, did not show a significant decrease in regional blood flow. The border between the fibrotic cryolesion and the surrounding myocardium is, therefore, sharply defined not only in terms of histology but also in regards to regional blood flow. These data lend further support to the safe clinical use of cryothermiamore » in the treatment of refractory ventricular tachycardia.« less

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
Duke Univ. Medical Center, Durham, NC
OSTI Identifier:
7133396
Resource Type:
Journal Article
Resource Relation:
Journal Name: J. Surg. Res.; (United States); Journal Volume: 5
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; MICROSPHERES; DIAGNOSTIC USES; MYOCARDIUM; BLOOD FLOW; BIOLOGICAL MODELS; CARDIOVASCULAR DISEASES; CRYOBIOLOGY; DOGS; HEART; SCANDIUM; SURGERY; ANIMALS; BIOLOGY; BODY; CARDIOVASCULAR SYSTEM; DISEASES; ELEMENTS; MAMMALS; MEDICINE; METALS; MUSCLES; ORGANS; TRANSITION ELEMENTS; USES; VERTEBRATES; 551001* - Physiological Systems- Tracer Techniques

Citation Formats

Holman, W.L., Ikeshita, M., Lease, J.G., Smith, P.K., Ungerleider, R.M., and Cox, J.L.. Cardiac cryosurgery: regional myocardial blood flow of ventricular cryolesions. United States: N. p., 1986. Web. doi:10.1016/0022-4804(86)90171-X.
Holman, W.L., Ikeshita, M., Lease, J.G., Smith, P.K., Ungerleider, R.M., & Cox, J.L.. Cardiac cryosurgery: regional myocardial blood flow of ventricular cryolesions. United States. doi:10.1016/0022-4804(86)90171-X.
Holman, W.L., Ikeshita, M., Lease, J.G., Smith, P.K., Ungerleider, R.M., and Cox, J.L.. 1986. "Cardiac cryosurgery: regional myocardial blood flow of ventricular cryolesions". United States. doi:10.1016/0022-4804(86)90171-X.
@article{osti_7133396,
title = {Cardiac cryosurgery: regional myocardial blood flow of ventricular cryolesions},
author = {Holman, W.L. and Ikeshita, M. and Lease, J.G. and Smith, P.K. and Ungerleider, R.M. and Cox, J.L.},
abstractNote = {Cryosurgery is one of three methods introduced recently for the treatment of ventricular tachyarrhythmias. Cryothermic exposure ablates arrhythmogenic ventricular myocardium, and produces a dense fibrous scar with a sharp border to histologically normal tissue. Myocardial blood flow in the region of the cryolesion, however, has not been quantitated. The purpose of this study was to measure regional blood flow within and around the cryolesion in an attempt to identify ischemic zones that might become arrhythmogenic. Left ventricular cryolesions were created in eleven adult dogs. Two weeks later, the animals underwent radioactive tracer microsphere injection for quantitation of regional myocardial blood flow. The fibrotic cryolesion demonstrated a significantly depressed blood flow (0.44 +/- 0.07 ml/min/g) compared to blood flow in control tissue (1.36 +/- 0.12 ml/min/g) (P less than 0.001). A 1-mm strip of myocardium immediately adjacent to the cryolesion, as well as other myocardium surrounding and subjacent to the cryolesion, did not show a significant decrease in regional blood flow. The border between the fibrotic cryolesion and the surrounding myocardium is, therefore, sharply defined not only in terms of histology but also in regards to regional blood flow. These data lend further support to the safe clinical use of cryothermia in the treatment of refractory ventricular tachycardia.},
doi = {10.1016/0022-4804(86)90171-X},
journal = {J. Surg. Res.; (United States)},
number = ,
volume = 5,
place = {United States},
year = 1986,
month =
}
  • To examine the effects of tachycardia on coronary circulation, transmural distribution of myocardial blood flow (MBF, 15-micron diameter radionuclide-labeled microspheres) was studied in six healthy adult ponies at rest (heart rate . 60 +/- 7 beats . min-1), during ventricular pacing at 150 and 200 beats . min-1, as well as with ventricular pacing at 250 beats . min-1 before and during maximal coronary vasodilatation (iv adenosine infusion; 4 mumole . kg-1 . min-1). Mean aortic pressure and cardiac output were unchanged from control values with ventricular pacing. Whereas ventricular pacing at 150 and 200 beats . min-1 resulted inmore » a progressive uniform increase in transmural MBF and well-maintained endo:epi perfusion ratio, pacing at 250 beats . min-1 did not result in a further increase in MBF compared to pacing at 200 beats . min-1 and the left ventricular (LV) subendocardial:subepicardial (endo:epi) perfusion ratio was significantly less than 1.00 (0.87 +/- 0.05). Blood flow to the LV papillary muscles and subendocardium was significantly less than that recorded at 200 beats . min-1. The LV endo:epi perfusion ratio with ventricular pacing at 250 beats . min-1 during adenosine infusion resulted in a decrease in mean aortic pressure (63% of control value) and a marked further reduction in blood flow to the LV papillary muscles as well as the LV subendocardium, while MBF increased dramatically in the LV subepicardium compared to values observed during ventricular pacing at 250 beats . min-1 alone. These data demonstrate that coronary vasomotion functions to maintain LV subendocardial blood flow in the pony myocardium at a heart rate of 200 beats . min-1, while at 250 beats . min-1 exhaustion of coronary vasodilator reserve in the deeper layers limits further increase in MBF.« less
  • The dual radionuclide myocardial distributions of imaging agents potassium-43 (/sup 43/K) and technetium-99m stannous pyrophosphate (/sup 99m/Tc-PYP) were studied in a 24-hour closed chest canine infarct preparation. In multiple myocardial biopsies in 20 dogs, tissue levels of both radionuclides were compared to either an index of tissue viability (myocardial creatine phosphokinase (CPK) depletion), or to estimates of regional myocardial blood flow as measured by the microsphere technique. Myocardial /sup 43/K uptake in the ischemic and infarcted zone correlated well with both CPK depletion (r = 0.73) and microsphere estimates of relative blood flow. The correlation with microspheres was excellent inmore » the transmural sample (r = 0.93) as well as endocardial (r = 0.97) and epicardial (r = 0.86) portions. On the other hand, /sup 99m/Tc-PYP myocardial uptake did not correlate with the extent of CPK depletion. Maximal uptake was frequently noted in border zones with only moderate CPK depletion, while lesser degrees of /sup 99m/Tc-PYP uptake were noted in the central infarct zone where CPK activity was lowest. The relationship of /sup 99m/Tc-PYP uptake to microsphere regional flow estimates demonstrated that /sup 99m/Tc-PYP uptake was maximal at flows of 0.3 to 0.4 of normal. At lower flows, /sup 99m/Tc-PYP uptake fell toward normal levels. A similar relationship was noted between the distributions of /sup 99m/Tc-PYP and /sup 43/K. In relatively high flow border segments (greater than or equal to 0.80 of normal), abnormal /sup 99m/Tc-PYP uptake of five to six times normal persisted. The transmural distribution of /sup 99m/Tc-PYP demonstrated that in low flow regions /sup 99m/Tc-PYP uptake was primarily epicardial, while in the higher flow ischemic periphery of the infarct endocardial uptake predominated.« less
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